AMIGA MACHINE LANGUAGE Typed by DEE JAY Table of Contents. ------------------ 1. Introduction 1.1 Why machine code? 1.2 A look into the Amiga's memory 1.2.1 RAM,ROM,hardware register 1.2.2 Bits,bytes and words 1.2.3 Number systems 1.3 Inside the Amiga 1.3.1 Components and libraries 1.3.2 Memory 1.3.3 Multi-tasking 2 The MC68000 processor 2.1 Registers 2.2 Addressing memory 2.3 Operating modes 2.3.1 User and supervisor modes 2.3.2 Exceptions 2.3.3 Interrupts 2.3.4 Condition codes 2.4 The 68000 Instructions 3 Working with assemblers 3.1 The development assembler 3.2 AssemPro 3.3 The K-SEKA assembler 4 Our first programs 4.1 Adding tables 4.2 Sorting tables 4.3 Converting number systems 4.3.1 Converting hex to ASCII 4.3.2 Converting decimal to ASCII 4.3.3 Converting ASCII to hex 4.3.4 Converting ASCII to decimal 5 Hardware registers 5.1 Checking for special keys 5.2 Timing 5.3 Reading the mouse or joystick 5.4 Tone production 5.5 Hardware registers overview 6 The Amiga operating system 6.1 Load libraries 6.2 Calling functions 6.3 Program initialization 6.3.1 Reserve memory 6.3.2 Opening a simple window 6.4 Input/output 6.4.1 Screen output 6.4.2 Keyboard input 6.4.3 Printer control 6.4.4 Serial I/O 6.4.5 Speech output 6.5 Disk operations 6.5.1 Open files 6.5.2 Reading and writing data 6.5.3 Erase files 6.5.4 Rename files 6.5.5 CLI directory 6.5.6 Read directory 6.5.7 Direct access to disk 7 Working with Intuition 7.1 Open screen 7.2 Openwindow 7.3 Requesters 7.4 Event handling 7.5 Menu programming 7.6 Text output 7.7 Images 7.8 Borders 7.9 Gadgets 7.9.1 Boolean gadgets 7.9.2 String gadgets 7.9.3 Proportional gadgets 7.10 Example program 8 Advanced programming 8.1 Supervisor mode 8.2 Exception programming Appendix Overview of library functions Overview of the MC68000 Instructions CHAPTER 1 --------- 1.Introduction. -------------- Before you tackle machine language,you should take a closer look at several things that are vital to machine language programming. 1.1.Why Machine Language. ------------------------ Machine language is actually the only language the MC68000 processor understands.All other languages,such as Basic,Pascal or C,must first be translated(interpreted or compiled) into machine code.This process can take place either when the program is executed(the BASIC interpreter),or before program execution(the Pascal and C compilers). Advantages; The great advantage of machine language over an interpreted and compiled program is machine language programs are faster. With an interpreter like BASIC,each line must first be interpreted before it is executed,which requires a great deal of time.A Pascal or C compiler translates the source into machine language.This translation procedure does not produce programs that are as fast as pure machine language programs. Another advantage machine language has over BASIC is that an interpreter is not needed for the execution of a machine language program. Machine language can access all the capabilities of the computor since it is the language native to the computor.It is possible that machine subroutines are required by a higher level language to access functions that aren't directly accessible by that language. 1.2.A Look Into The Amiga's Memory. ---------------------------------- Before a machine language program can be written,you must know exactly what the program is required to do.You must also be aware of what resources are needed and available to achieve those goals.The most important of these resources is the memory in the Amiga. 1.2.1.RAM,ROM,Hardware Register. ------------------------------- Random Access Memory,referred to as RAM,allows information to be placed in it and then withdrawn at a later time.This memory consists of electronic componants that retain data only while the computor is turned on(or until power failure). So that the computor is able to do something when it is first turned on,such as promting the Workbench or Kickstart disk,a program has to remain in memory when the power is off.A memory type which can retain data in memory without any power being needed.This second memory type is known as ROM. ROM; ROM stands for Read Only Memory,indicating that data can only be read from this memory,not written to it.The Amiga contains a ROM,that loads the Workbench or Kickstart disk into RAM.The first version of the Amiga did not contain the Kickstart in ROM. PROM; One variation of ROM is the PROM,or Programmable Read Only Memory.This special type of ROM can actually be programmed once.Since it cannot be erased once programmed,it isn't encountered very often.More often you will see EPROM's. or Erasable Programmable ROM's.These special chips,which can be erased with ultraviolet light,have a little window on the surface of the chip usually covered with tape. EEROM; Although not available on the consumer market and much more expensive than RAM,the EEROM(Electically Erasable ROM) offers another alternative to programmable ROM.These chips function like RAM,except that information is not lost when the power is turned off. WOM; With the birth of the Amiga,another type of memory,WOM,was created.This particular type of memory is Write Once Memory. The Kickstart disk is read into this memory when the computor is first booted.After this,no more data can be read into that memory.Actually this isn't a completely new component,but simply RAM that is locked once data has been read into it, after which the data can only be read from that memory. Registers; In addition to RAM and these variations of ROM there is another type of memory situated between those two groups.This memory is connected to the processor through a group of peripheral controllers.Thus it is commonly refered to as the Hardware Register,since the computor's hardware is managed by this system.We'll go into greater detail on how to use these hardware registers later in this book. Lets take a closer look at the structure and use of the memory most familiar to us,RAM. 1.2.2.Bits,Bytes,and Words. -------------------------- Kilobyte; The standard size in which memory is measured is a Kilobyte (Kbyte).One kilobyte consists of 1024 bytes,not 1000 as you might expect.This unusual system stems from the computor's binary mode of operation,where numbers are given as powers of 2,including kilobytes. To access a memory block of one kilobyte,the processor requires 10 connections which carry either one volt or zero volts.Thus 2^10=1024 combinations or 1024 bytes of memory,are possible. Byte; A byte,in turn,consists of yes/no,on/off information as well. A byte can be one of 2^8 different values,and thus it can represent any one of 256 numbers.The individual numerical values that make up a byte,which also are the smallest and most basic unit encountered in any computor,are called bits (short for binary coded digit). A 512 kbyte memory,such as the Amiga's,contains 2^19=524288 bytes and 4194304 bits.It may seem unimaginable,but a memory of that size has 2^4194300 different combinations. Word; Back to the basics...bits and bytes are sufficent to program an eight bit processor like the 6500,since it can only work with bytes.To program a 16/32 bit processor like the Amiga's MC68000,you'll need to know two new data forms:words,consisting of 16 bits(the equivalent of two bytes),and long words,which are 32 bits(the equivalent of four bytes,or 2 words). A word can be any number between 0 and 65536,a long word can 0 to 4294967295.The MC68000 processor can process these gigantic numbers with a single operation. Once in a while you need to use negative numbers as well as positive ones.Since a bit can only be 1 or 0 and not -1,an alternative system has been adopted.If a word is to have a specific sign,the highest value digit or 15th bit in the word (positions are always counted from zero) determines the sign of the word.With this method words can carry values from -32768 to +32768.One byte can range from -127 to +127.In a byte,the value -1 is given by $FF; in a word it's $FFFF,-2 is $FE(FFFE), etc. Lets stick with positive values for the time being,to aid in the visualization of a bit in relation to its bit pattern. Machine language does not use the familiar decimal system. Instead,it commonly employs the binary as well as the octal and hexadecimal number systems. 1.2.3.Number Systems. -------------------- Lets take a look at the decimal system:its base number is 10. This means that every digit represents a power of 10.This means that the 246 represents 2*10^2+4*10^1+6*10^0.The decimal system offers a selection of 10 characters,namely 0-9. Binary; This procedure is different for the binary system.The binary system offers only two different characters:1 and 0.Thus the systems base number is two.The decimal value of 1010 would be: 1*2^3+0*2^2+1*2^1+0*2^0=2^3+2^1=8+2=10 (in decimal system) Generally binary numbers are identified by having a percentage symbol as a prefix.See if you can determine the decimal value of this number:110010... Well did you get 50?.Thats the right answer.The most simple method to arrive at this result is to simply add up the values of the digits contained at 1.The values of the first eight digits are as follows: digit 8 7 6 5 4 3 2 1 value 128 64 32 16 8 4 2 1 Octal; The octal system whose base is eight,is similar.The character set consists of numbers 0 to 7.The decimal equivalent of the octal number 31 is: 3*8^1+1*8^0=25.However the octal system isn't nearly as important as the next one... The base number of the hexadecimal system is 16,and its character set ranges from 0 to F.Thus,A would be equivalent of a decimal 10 and F would be 15.The dollar sign($) indicates a hexadecimal number.The binary and hexadecimal systems are the most important numerical systems for assembly language programming. Hex; The hexadecimal representation of a byte ranging from 0 to 256 always has two digits:$00 to $FF.A word ranges from $0000 to $FFFF and a longword from $00000000 to $FFFFFFFF. Its quite easy to convert binary numbers into hexadecimal:simply split up the binary numbers into groups of four digits.Each of these groups of four digits then corresponds to one hexadecimal digit.Heres an example: binary number %110011101111 split up %1100 %1110 %1111 result $C $E $F thus: %110011101111=$CEF The opposite operation is just as easy... hexadecimal $E30D split up $E $3 $0 $D result %1110 %0011 %0000 %1101 thus: $E30D = %1110001100001101 This method can also be used to convert binary into octal and vice versa,except that groups of three digits are used in that case: octal number 7531 split up 7 5 3 1 result %111 %100 %011 %001 thus: octal 7531=%111101011001 This binary number can the be converted into hexadecimal,as well: binary number %111101011001 split up %1111 %0101 %1001 result $F $5 $9 thus: octal 7531=$F59 The following calculation can then be used to convert the number into the familiar decimal system: hexadecimal $F59 split up $F $5 $9 result 15*16^2+5*16+9 thus: $F59=3929 decimal Although this conversions are quite simple ,they can get to be rather annoying.Many assemblers can ease this task somewhat:they allow you to enter a value with '?'upon which it returns the value in decimal and hexadecimal forms.There are even calculators that perform number base conversions. Often this conversion as to be performed in a program,for instance when a number is entered by the user and then processed by the computor.In this case the number entered,being simply a combination of graphic symbols,is evaluated and the usually converted into a binary number,in effect,a word or a longword. This process is often required in reverse order,as well.If the computor is to display a calculated value in a specific number system,it must first convert that number into a series of characters.In a later chapter you will develop machine language routines to solve these problems.You can then use these routines in your own programs.First you still have to cover some things that are fundamental to machine language programming on the Amiga. 1.3.Inside the Amiga. -------------------- In order to program machine language,it is not sufficent to know only the commands of the particular processor,one must also have extensive knowledge of the Amiga being programmed.Lets take a look inside the Amiga. 1.3.1.Components and Libraries. ------------------------------ The Amiga is a very capable machine,due to the fact that there are components that do a large part of the workload,freeing up the 68000 processor.These are refered to as the"custom"chips, which perform various tasks independantly of the 68000 processor. Custom Chips; This task force is comprised of three chips,whose poetic names are Agnus,Denice,and Paula.The main task of Agnus,alias blitter, is the shifting of memory blocks,which is helpful for operations such as quick screen changes.Denise is responsible for transfering the computors thoughts on to the screen.Paula's tasks consist of input/output jobs,such as disk operation or sound. These chips are accessed by the processor through several adresses starting at $DFF000,which are also known as the hardware registers (you'll find more detailed information about the registers in the corresponding chapter).To simplify the otherwise complicated procedure of utilizing these chips,several programs have been included in the Kickstart and Workbench libraries.These programs can be called by simple routines and then take over the respective chips. If only these library functions are used to program the Amiga,the parameters are the same,regardless of the language used.Only the parameter notations differs from language to language.BASIC is an exception in this respect,since its interpreter translates the program calls,which is why you don't need to know how the Amiga executes these functions in order to use them. The library functions are written in machine language and are thus closely related with your own machine language programs.Actually you could do without the library programs and write all of the functions yourself.However the incredible workload of this task is so discouraging,that you'd rather stick with the library functions 1.3.2.Memory. ------------ First lets look at the RAM of the Amiga 1000.The standard version of this computor has over 512 kbytes of RAM,ranging from the address $00000 to $7FFFF,or 0 to 524287.If the memory is expanded to one megabyte,the first address still starts at $00000,however the start of anything greater than 512k can go anywhere in the address space between $200000 to $9FFFFF.With the release of AmigaDOS 1.2,the Amiga figures out where to put the memory expansion by using a special`Autoconfig`scheme.This allows you to add memory and I/O without worrying about addresses and dip switches. Chip RAM; The chips that support the Amiga`s processor access RAM almost totally independantly and thus ease the workload of the processor. However there is a draw back:these chips can only access the first 512k bytes of RAM.Thus graphics and sound data handled by these chips MUST be stored in this memory range.Because of this,that memory range is referred to as `Chip RAM`. Fast RAM; The counterpart to chip RAM is the remaining RAM which,if the computor is equipped with it,begins at $200000.Since only the processor itself as access to this part of memory it is known has `Fast RAM`. Here`s an overview of the Amiga`s memory: $000000-$07FFFF chip RAM $080000-$1FFFFF reserved $200000-$9FFFFF potential fast RAM $A00000-$BEFFFF reserved $BFD000-$BFDF00 PIA B (even addresses) $BFE001-$BFEF00 PIA C (odd addresses) $C00000-$DFEFFF reserved for expansion $DFF000-$DFFFFF custom chip registers $E00000-$E7FFFF reserved $E80000-$EFFFFF expansion ports $F00000-$F7FFFF reserved $F80000-$FFFFFF system ROM Since the Amiga is multi-tasking,when a program is loaded into memory,it is simply loaded into another memory location.The memory range thus occupied is added to a list of occupied memory and the memory range is then considered barred from other uses.If another program is loaded,which is quite possible with the Amiga,it is read into another memory location which is then marked on the occupied list.If the first program should require additional memory,to use a text buffer for example,that memory first has to be reserved.Otherwise another program could accidently be loaded into the memory needed for this task. What`s interesting about this procedure is that when the first loaded has ended,the memory occupied by it is freed for further use.As a result,RAM is then chopped up into occupied and free parts,which are no longer related to each other.The Amiga can still utilize these chunks of memory as if they were one continuous chunk.After all,parts is parts.An example of this is the dynamic RAM disk which is always available under the name RAM: This RAM disk is actually quite a phenomenon,since it is always completely filled.If a program is erased from RAM disk,the memory allocated to that program,regardless of its location or structure, is given back to the system.Thus,if you reserved and filled 100 kbytes of memory,it would be quite posible that the 100kbytes actually consists of various pieces of memory independant of one another.You never notice this since the Amiga automatically corrects the difference between apparent and actual memory. 1.3.3.Multi-Tasking. ------------------- The Amiga is truly an amazing machine,being capable of doing several things at one time.A red and white ball might be bouncing around in one window while you`re working on text in another window and watching a clock tick away in a third. At least that`s the impression most people get when they recieve their first Amiga demonstration.However,there is a catch to this: even the Amiga as only one processor,which can really only do one thing at a time. The tricky part is when more than one program is running,each program is executed part by part,and the Amiga is constantly switching from one program back to the other program.In the example above,the ball would first be moved by one pixel,then the processor would check for a text entry and if necessary display it,after which it would move the clock`s second hand.This procedure would be repeated over and over,as the three programs are executed together.The problem is,that the greater the work load on the processor,the slower the things happen.Thus,programs run slower during heavy multi-tasking. Tasks; Each of these jobs that the Amiga has to execute are commonly referred to has tasks...thus,multi-tasking.During multi-tasking, each task is assigned a special time segment during which that particular task is executed.These time segments can be controlled, so that more time consumming programs can be allotted somewhat more processing time. The programmer actually doesn`t need to know how this time slicing works.You can write aprogram without paying any attension to multi-tasking and then run it simultaneously with another program running in the background.The only restriction is that you`ll have to start the program from the CLI with`run`,or from the Workbench. If you execute the program from the CLI by simply typing its name, the processor allots all the time it can get from the CLI to that program,until the execution is complete.Starting the program with run free`s the CLI for other uses while the program is being executed. There is another restriction regarding multi-tasking that applies to assembler programmers.Aside from the use of extra memory,which must first be reserved,the hardware registers should not be directly accessed.Instead the library functions should be used.The reason for this is quite simple: Should you,for instance,specify the printer port as the input line and are reading data in,another task might suddenly think its supposed to be printing.The line would thus be switched to output and data would be written out.After this,your program would try to read more data in,which would not be possible. This is an oversimplified example,but it points out the problem nevertheless.In real programming situations the effects of multiple direct programming of the hardware registers can be much more catastrophic.If your program still needs to access the hardware registers directly(which can have some advantages),then make sure that the program always runs by itself. Chapter 2. --------- 2.The MC68000 Processor. ----------------------- The Amiga`s MC68000 processor is a 16/32 bit processor,which means that while it can process data of 32 bits,it"only"has a 16 bit data bus and a 24 bit address bus.Thus,it can access 2^24=16777216 bytes(or 16 Mbytes)of memory directly. 7.1 Megaherz; The Amiga 68000 processor,running at 7.1 megaherz,is quite fast, which is required for a computor with a workload as heavy as the Amiga`s.The Amiga also processes a number of custom chips that greatly ease the workload of the processor.These custom chips manage sound in/output,graphics and animation,thus freeing the processor for calculations. 2.1.Registers. ------------- In addition to the standard RAM,the processor contains internal memory called registers.There are eight data registers(D0-D7), eight address registers(A0-A7),a status register(SR),two stack pointers,a user stack pointer,a system stack pointer(USP and SSP) and the program counter(PC). Register Sizes; The data registers,the address registers,and the program counter are all 32 bits,while the status register is 16 bits.These registers are located dirctly in the processor so they are not accessed the same way memory would be accessed.There are special instructions for accessing these registers. Data Registers; The data registers are used for all kinds of data.They can handle operations with bytes(8 bits)words(16 bits)and longwords(32bits). Address Registers; The address registers are used for storing and processing addresses.This way they can be used as pointers to tables,in which case only words and longwords operations are possible. Stack Pointer; The address register A7 plays a special role:this register is utilized as the Stack Pointer(SR)by the processor,and thus is not recommended for normal use by the programmer.Which of the two possible stacks is being pointed to depends on the present mode of the processor,but more about that later. The stack,to whose actual position the stack pointer is pointing, is used to store temporary internal data.The stack works similar to a stack of notes on your desk:the note that was added to the stack last is the first one to come off the stack.This type of stack is known as LIFO(Last in,First out).There is another type of stack,the FIFO(First in,First out)which is not used by the processor itself. How these registers and the SP can be manipulated,or how to work with the stack,is presented in the next chapter.Lets continue with the registers for now. Status Register; The status register plays an important role in machine language programming.This 16-bit quality(word)contains important information about the processor status in 10 of its bits.The word is divided into two bytes,the lower byte(the user byte)and the upper byte(the system byte).The bits that signify that certain conditions are refered to as flags.This means that when a certain condition is present,a particular bit is set. The user byte contains five flags,which have the following meaning Bit Name Meaning ----------------------------------------------- 0 (C,Carry) Carry bit,modified by math calculation,and shift instructions. 1 (V,Overflow) Similar to carry,indicates a change of sign,in other words,a carry from bit six to bit seven. 2 (Z,Zero) Bit is set when the result of an operation is zero. 3 (N,Negative) Is set when the result of an operation is negative. 4 (X,Extended) Like carry,is set for arithmetic operations. 5-7 Not used. The system byte contains five significant bits: Bit Nane Meaning ----------------------------------------------- 8 I0 Interupt mask.Activates interupt 9 I1 levels 0 to 7,where 0 is the lowest 10 I2 and 7 is the highest priority. 11 not used. 12 not used. 13 (S,Supervisor) This bit indicates the actual pocessor mode(0=User,1=Supervisor mode). 14 not used. 15 (T,Trace) If this bit is set,the processor is in single step mode. Here's an overview of the status word; bit : 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 name : T - S - - I2 I1 I0 - - - X N Z V C Don't let the new terms,like mode and interupt confuse you.We'll talk about these in greater detail in the chapter dealing with the operating conditions of the processor. 2.2.Addressing Memory. --------------------- In the standard Amiga 500's and 1000's,the processor has over 512k of RAM available.The Amiga 2000 has one mega-byte of RAM that can be accessed by the processor.How does the processor access all this memory? If you're programming in BASIC you don't have to worry about memory management.You can simply enter MARKER%=1,and the value is stored in memory by the BASIC interpreter. In assembler,there are two ways of accomplishing this task: 1) Store the value in one of the data or address registers,or 2)Write it directly into a memory location. To demonstrate these two methods let's get a little ahead and introduce a machine language instruction,which is probably the most common:MOVE.As its name states,this instruction moves values. Two parameters are required with the instruction:source and destination. Lets see what the example from above would look like if you utilize the MOVE instruction... 1) MOVE #1,D0 This instruction moves the value 1 into data register D0.As you can see,the source value is always entered before the destination. Thus,the instruction MOVE D0,#1 is not possible. 2) MOVE #1,$1000 deposits the value 1 in the memory location at $1000.This address was arbitrarily chosen.Usually addresses of this form won't be used at all in assembler programs,since labels that point to a certain address are used instead.Thus,the more common way of writing this would be: ... MOVE #1,MARKER ... MARKER:DC.W 1 These are actually two pieces of program:the first part executes the normal MOVE instruction whose destination is `MARKER`.This label is usually defined at the end of a program and specifies the address at which the value is stored. The paraneter DC.W 1 is a pseudo op,apseudo operation.This means that this isn`t an instruction for the processor,but an instruction for the assembler.The letters DC stand for`DeClare`and the suffix .W indicates that the data is a Word.The other two suffix alternatives would be .B for a byte(8 bits)and .L for a long word(32 bits). This suffix(.B.W or.L)is used with most machine language instructions.If the suffix is omitted,the assembler uses .W(word) as the default parameter.If you wanted a long word,you`d use an instruction that looks something like this:MOVE .L #$1234678,D0 where as an instruction like MOVE.B #$12,D0 would be used for a byte of data.However,with this instruction there`s one thing you must be aware of... CAUTION: If the memory is accessed by words or long words,the address must be even(end digit must be 0,2,4,6,8,A,C,E)! Assemblers usually have a pseudo-op,`EVEN`or`ALIGN`,depending on the assembler,that aligns data to an even address.This becomes necessary in situations similar to this: ... VALUE1: DC.B 1 VALUE2: DC.W 1 If the VALUE1 is located at an even address,VALUE2 is automaticaly located at an odd one.If an ALIGN(EVEN)is inserted here,a fill byte(0)is inserted by the assembler,thus making the second address even. ... VALUE1: DC.B 1 ALIGN VALUE2: DC.W 1 Back to the different ways of addressing.The variations listed above are equivalent to the BASIC instruction MARKER%=1 where the % symbol indicates an integer value. Lets go a step further and translate the BASIC instruction MARKER %=VALUE% into assembler.You`ve probably already guessed the answer right? MOVE VALUE,MARKER ... ... MARKER: DC.W 1 VALUE : DC.W 1 In this case,the contents in the address at VALUE are moved into the address at MARKER. With the help of these simple examples,you`ve already become familiar with four different ways of addressing,in other words, ways that the processor can access memory.The first is characterized by the number sign(#)and represents a direct value. Thus,this method is also known as direct addressing,and is legal only for the source parameter! A further method in which a direct address(in our case,`MARKER`and `VALUE`)can be specified is known as absolute addressing.This method is legal for the source parameter as well as for the destination parameter. This method can be divided into two different types,between which the programmer usually does'nt notice a difference.Depending on whether the absolute address is smaller or larger than $FFFF,in other words if it requires a long word,it is called absolute addressing(for addresses above $FFFF)or otherwise absolute short addressing.The assembler generally makes the distinction between these two types,and thus,only general knowledge of absolute addressing is required. The fourth method of addressing that you've encountered so far is known as DATA REGISTER DIRECT.It was the first one introduced(MOVE #1,D0)in conjunction with direct addressing,the only difference being that this type accesses a data register(such as D0). These four methods aren't the only ones available to the MC68000 processor,in fact there are a total of 12.One other variation called ADDRESS REGISTER DIRECT,is almost identical to data register direct,except that it accesses the address register instead of the data register.Thus,you can use MOVE.L #MARKER,A0 to access the address register A0 directly. You now know five ways to address memory with which quite a bit can be accomplished.Now,lets tackle something more complicated and more interesting. Lets take another example from BASIC: 10 A=1000 20 POKE A,1 In this example the first line assigns the value 1000 to the variable A.This can be done in assembler as well:MOVE.L #1000,A0. In the assembler version the absolute value of 1000 ia stored in the address register A0. Line 20 doesn't assign a value to the variable A itself,but rather to the memory location at the address stored in A.This is an indirect access,which is quite easy to duplicate in assembler: MOVE.L #1000,A0 ;bring address in A0 MOVE #1,(A0) ;write 1 into this address The parentheses indicates an addressing known as ADDRESS REGISTER INDIRECT.This method only works with address registers,since a 'data register indirect' does not exist. There are several variations of this method.For instance,a distance value can be specified,which is added to the address presently located in the address register before the register is actually accessed.The instruction MOVE #1,4(A0),if applied to the example above,writes the value 1 into the memory cell at 1000+4= 1004.This distance value can be positive or negative.Thus,values from -32768 to +32768 are accepted.This specific variation of addressing is called ADDRESS REGISTER INDIRECT WITH A 16 BIT DISPLACEMENT value. There is another very similar variation:ADDRESS REGISTER INDIRECT WITH AN 8 BIT INDEX value.While this variation is limited to 8 bits,it also brings another register into play.This second register is also a distance value,except that it is a variable as well. We'll try to clarify this with an example.Lets assume that a program includes a data list that is structured like this: ... RECORD: DC.W 2 ;number of entries -1 DC.W 1,2,3 ;elements of list We'll use MOVE.L #RECORD,A0 to load the list into the address register A0.Then you can use MOVE (A0),D0 to pull the number of in the list into the data register.To access the last element of the listonly one instruction is needed.The whole thing looks something like this: CLR.L D0 ;erase D0 completely MOVE.L #RECORD,A0 ;address of list in A0 MOVE (A0),D0 ;number of elements -1 in D0 MOVE 1(A0,D0),D1 ;last element in D1 ... RECORD: DC.W 2 ;number of entries -1 DC.W 1,2,3 ;elements of list This last instruction accesses the byte that is located at 1+A0+D0 in other words,the record +1 where the data begins plus the contents of D0(in this case 2). This method of accessing is very useful.It works exquisitely for the processing of tables and lists,as the example demonstrates.If no distance value is needed,simply use a distance value of zero, which some assemblers automatically insert as the default value if for instance only MOVE (A0,D0)is entered. The latter two methods have a third variation,which as its own characteristic trait.It dosen't utilize an address register,but uses the Program Counter(PC)instead.The program counter with displacement method proves useful when a program must function without any changes in all address ranges.The following two statements(in the 15 bit limits)have the same effect: MOVE MARKER,D0 and MOVE MARKER(PC),D0 This method is actually rather imprecise,since the first instruction specifies the actual address of the marker with MARKER while the second line specifies the distance between the instruction and the marker.However since it would be quite cumbersome to constanly calculate the distance,the assembler takes this task off our hands and calculates the actual value automatic. Lets examine the difference between the two instructions.In a program they'll accomplish the same thing,although they are interpreted as two completely different things by the assembler. You'll assume a program being at the address $1000 and the marker is located at $1100.The generated program code looks something like this: $001000 30 39 00 00 11 00 MOVE MARKER,D1 or $001000 30 3A 00 FE MOVE MARKER(PC),D1 As you can see,the generated code of the second line is two bytes shorter than the first line.In addition,if you were to shift this code to the address $2000,the first version still accesses the memory at $1100,while the second line using the PC indirect addressing accesses memory at $2000 correctly.Thus,the program can be transferred to almost any location. This,then,is PROGRAM COUNTER WITH 16 BIT DISPACEMENT value.As we mentioned,there is also PROGRAM COUNTER WITH 8 BIT INDEX value, which permits a second register as a distance value,also known as offset. There are two addressing modes left.These two are based on indirect addressing.They offer the capability of automatically raising or lowering the address register by one when memory is accessed with address register indirect. To automatically increase the register,you'd use ADDRESS REGISTER DIRECT WITH POST-INCREMENT.The address register raises this by the number of bytes used AFTER accessing memory.Thus if you write: MOVE.L #1000,A0 MOVE.B #1,(A0)+ the 1 is written in the address $1000 and then A0 is raised by one Instructions like this are very helpful when a memory range is to be filled with a specific value(for instance when the screen is cleared).For such purposes the instruction can be placed in a loop ...which we'll get to later. The counter part to post increment is ADDRESS REGISTER WITH PRE- DECREMENT.In this case the specified address register is lowered by one BEFORE the access to memory.The instructions: MOVE.L #1000,A0 MOVE.B #1,-(A0) writes 1 in the address 999,since the contents of A0 is first decremented and the 1 is written afterwards. These two methods of addressing are used to manage the stack pointer(SP).Since the stack is filled from top to bottom,the following is written to place a word(s.aD0)on the stack: MOVE.B D0,-(SP) and to remove it from the stack,again in D0: MOVE.B (SP)+,D0 This way the stack pointer always points to the byte last deposited on the stack.Here,again,you'll have to be careful that an access to the stack with a word or a long word is always on an even address.Thus,if you're going to deposit a byte on the stack, either use a whole word or make sure the byte is not followed by a JSR or BSR.The JSR or BSR instructions deposit the addresses from which they stem on the stack in the form of a long word. In the code above,the SP is generally replaced by the address register A7 in the program code,since this register is always used as the SP.Thus,you can write A7 as well as S,the resulting program is the same.However,we recommend the use of SP,since this makes the code somewhat easier to read.After all,quite often you'll want to employ your own stacks,in which case the difference between the processor stack and your own stacks become very important. These are the twelve ways of addressing the MC68000 processor,Here is a summary: No Name Format -- ---- ------ 1 data register direct Dn 2 address register direct An 3 address register indirect (An) 4 address register indirect with post-increment (An)+ 5 address register indirect with pre-decrement -(An) 6 address register indirect with 16 bit displacement d16(An) 7 address register indirect with 8 bit index value 8(An,Rn) 8 absolute short xxxx.W 9 absolute long xxxxxxxx.L 10 direct #'data' 11 program counter indirect with 16 bit displacement d16(PC) 12 program counter indirect with 8 bit index value d8(PC,Rn) The abbreviations above have the following meanings: An address registers A0-A7 Dn data registers D0-D7 d16 16 bit value d8 8 bit value Rn register D0-D7,A0-A7 'data' up to 32 bit value,(either .B .W .L) These are the addressing modes used by the MC68000 processor.The bigger brother of this processor,the 32 bit MC68020,has six more methods which we won't discuss here. Next you're going to see under what conditions the processor can operate. 2.3.Operating Modes. ------------------- In the previous section about registers you encountered the Status Register(SR).The individual bits of this register reflect the present operating condition of the processor.You differentiated between the system byte(bits 8-15)and the user byte(bits 0-7).Now, lets take a closer look at the system byte and its effects upon the operation of the processor. 2.3.1.User and Supervisor Modes. ------------------------------- Isn't it rather strange that the processor classifies you either as a'user'or a 'supervisor'?Both of these operating modes are possible,the user mode being the more common mode.In this mode it is impossible to issue some instructions,and that in your own computor! Don't worry though,you can get around that,as well.The Amiga's operating system contains a function that allows us to switch the processor from one mode to the other. The mode is determined by bit 13 of the Status Register.Usually this bit is cleared(0),indicating that the processor is in user mode.It is possible to write directly into the status register, although this is a privileged instruction that can only be executed from the supervisor mode.Thus,this instructioncould only be used to switch from the supervisor mode into the user mode,by using AND #$DFFF,SR to clear the supervisor bit.However,it is quite preferable to let the operating system perform the switch between these two modes. Now what differentiates these two modes in terms of application? Well,we already mentioned the first difference:some instructions, such as MOVE xx,SR, are privileged and can only be executed from the supervisor mode.An attempt to do this in user mode would result in an exception and interruption of the program.Exceptions are the only way of switching to the supervisor mode,but more about later. A further difference is in the stack range used.Although A7 is still used as the stack pointer,another memory range is used for the stack itself.Thus,the SP is changed rach time you switch from one mode to the other.Because of this you differentiate between the User(USP)and the Supervisor SP(SSP). Accessing memory can also depend on these two modes.During such accessing,the processor sends signals to the peripheral components informing them of the current processor moce.This way a MC68000 computor can protect(privilege)certain memory ranges so they can't be accessed by the user. In the supervisor mode it is possible to execute all instructions and access all areas of memory.Because of this,operating systems usually run in the supervisor mode.This is accomplished through the use of Exceptions. 2.3.2.Exceptions. ---------------- Exceptions are similar to interupts on 6500 computors.This allows stopping a program,running a sub-program,and then restarting the stopped program.When an exception occurs the following seps are taken: 1) The status register is saved. 2) The S bit in SR is set(supervisor mode)and the T bit is cleared(no trace). 3) The program counter and the user SP are saved. 4) The exception vector,which points to the needed exception routine,is retrieved. 5) The routine is executed. The vectors mentioned,which contain the starting addresses for the various routines,are located at the very beginning of the memory. Here is an overview of the vectors and their respective addresses: Number Address Used for ----- ------ -------- 0 $000 RESET:starting SSP 1 $004 RESET:starting PC 2 $008 bus error 3 $00C address error 4 $010 illegal instruction 5 $014 division by zero 6 $018 CHK instruction 7 $01C TRAPV instruction 8 $020 privilege violation 9 $024 trace 10 $028 Axxx-instruction emulation 11 $02C Fxxx-instruction emulation $030-$038 reserved 15 $03C uninitialed interrupt $040-$05F reserved 24 $060 unjustified interrupt 25-31 $064-$083 level 1-7 interrupt 32-47 $080-$0BF TRAP instructions $0C0-$0FF reserved 64-255 $100-$3FF user interrupt vectors The individual entries in the table above need detailed explanation.So lets go through them one by one... RESET:staring SSP; At reset,the long word stored at this location is used as the stack pointer for the supervisor mode(SSP).This way you can specify the stack for the RESET routine. RESET:starting PC; Again at reset,the value at this location is used as the program counter.In other words,the RESET routine is started at the address stored here. Bus Error; This exception is activated by a co-processor when,for instance,a reserved or non-existant memory range is accessed. Address Error; This error occurs when a word or long word access is atempted at an odd address. Illegal Instruction; Since all MC68000 instructions consist of one word,a total 65536 different instructions are possible.However,since the processor doesn't that many instructions,there are a number of words that are invalid instructions.Should such a word occur,the exception is prompted. Division by Zero; Since the processor has a division function,and the division of anything by zero is mathematically undefined and thus illegal,this exception occurs when such an operation is attempted. CHK Instruction; This exception only occurs with the CHK instruction.This instruction tests that a data registers contents are within a certain limit.If this is not the case,the exception is activated. TRAPV Instruction; If the TRAPV instruction is executed and the V bit(bit 1)in the status word is set,this exception is prompted. Privilege Violation; If a privileged instruction is called from the user mode,this exception is activated. Trace; If the trace bit(bit 15)in the status word is set,this exception is activated after each instruction that is executed.This method allows you to employ a step by step execution of machine programs. Axxx-Instruction Emulation; Fxxx-Instruction Emulation; These two vectors can be used for a quite interesting trick.If an instruction beginning with $A or $F(such as $A010 or $F200)is called the,the routine to which the corresponding vector is pointing is accessed.In these routines you can create chains of other instructions,in effect expanding the processors instruction vocaulary! Reserved; These vectors are not used. Uninitialized Interrupt; This exception is activated when a peripheral component that was not initialized sends an interrupt. Unassigned Interrupt; Is activated when a BUS error occurs during the interrupt verification of the activating component.However,the interrupt is usually only by some type of disturbance. Level 1-7 Interrupt; These seven vectors point to the interrupt routines of the corresponding priority levels.If the level indicated in the status word is higher than the level of the occuring interrupt,the interrupt is simply ignored. TRAP Instructions; These 16 vectors are used when a corresponding TRAP instruction occurs.Thus,TRAP instructions from TRAP #0 to TRAP #15 are possible. User Interrupt Vectors; These vectors are used for interrupts which are activated by several peripheral components that generate their own vector number. At this point you don't want to delve any deeper into the secrets of exceptions,since we'd be expanding this book beyond its frame work.However,there's one last thing to say about exceptions:the exception routines are ended with the RTE(ReTurn from Exception) instruction,with which the original status is restored and the user program is continued. 2.3.3.Interrupts. ---------------- Interrupts are processed similarly to exceptions.They are breaks (or interruptions)in the program which are activated through hardware(such as a peripherical component or an external trigger). The interrupt level is stored in bits 8-10 of the status register. A value between 0 and 7 indicates the interrupt level.There are eight possible interrupts,each of which as a different priority.If the level of this interrupt happens to be higher than the value in the status register,the interrupt is executed,or else ignored. When a valid interrupt occurs,the computor branches to the corresponding routine whose address is indicated in the exception vector table above. The interrupts are very important if you're trying to synchronize a program with connected hardware.In this manner,a trigger(s.a the keyboard)which is to feed the computor data,can signal the request for a legal value using an interrupt.The interrupt routine then simply takes the value directly.This method is also employed for the operation of the serial interface(RS232). We'll talk about the use of interrupts at a later time.The last thing we want to mention about interrupts at this time is that, like exceptions,interrupt routines are terminated with the RTE instruction. 2.3.4.Condition Codes. --------------------- When you write a program in any language,the need for a conditional operation arises quite often.For instance,in a BASIC program IF D1=2 THEN D2=0 represents a conditional operation.To write the equivalent in machine language,you first need to make the comparison: CMP #2,D1 CMP stands for compare and compares two operands,in this case D1 and D2.How is this operation evaluated? For this purpose you have condition codes(CC's),which exist in the branch instructions of machine language.Because of this,you must specify when and where the program is to branch. The simplest variation of the branch instruction is an unconditional branch.The corresponding instruction is 'BRA address ',although this won't help you here.After all,you need a conditional branch. To retain the result of the operation,in this case a comparrison (CMP),several bits are reserved in the status word.Lets look at bit 2 first,which is the zero flag.This flag is set when the result of the previous operation was zero. To explain the relationship between CMP and the Z flag,you must first clarify the function of the CMP instruction.Actually this instruction performs the subtraction of the source operand from the destination operand.In the example above,the number 2 is subtracted from the content of the memory cell at D1.Before the result of this subtraction is discarded,the corresponding flags are set. If the contents of D1 in our example above happened to be 2,the result of the subtraction would be 0.Thus,the Z flag would be set, which can then be evaluated through a corresponding branch instruction.Our example would then look like this: ... CMP #2,D1 ;comparison,or subtraction BNE UNEQUAL ;branch,if not equal(Z flag not set) MOVE #0,D2 ;otherwise execute D2=0 UNEQUAL: ... ;program branches to here BNE stands for Branch if Not Equal.This means,that if the Z flag was cleared(=0)by the previous CMP,the program branches to the address specified by BNE(here represented by UNEQUAL).The counter part to the BNE instruction is the BEQ(Branch if EQual)instruction which is executed if Z=1. Here's a list of condition codes,which allow you to form conditional branches using the Bcc(cc=condition code)format: cc Condition Bits --------------------------------------------------- T true,corresponds to BRA F false,never branches HI higher than C'* Z' LS lower or same C + Z CC,HS carry clear,higher or same C' CS,LO carry set,lower C NE not equal Z' EQ equal Z VC overflow clear V' VS overflow set V PL plus,positive MI minus,negative GE greater or equal N*V+N'*V' LT less than N*V'+N'*V GT greater than N*V*Z'+N'*V'*Z' LE less or equal Z + N*V' + N'*V *=logic AND, +=logic OR, '=logic NOT Here are a few examples to demonstrate how these numerous conditions can be utilized: CMP #2,D1 BLS SMALLER_EQUAL This branches if the contents of D1<=2,whether D1 is 0,1 or 2.In this example,the BLE instruction would allow the program to branch even if D1 is negative.You can tell this by the fact that the V bit is used in the evaluation of this expression(see chart above). When the sign is changed during the operation,this V bit is compared with the N bit.Should both bits be cleared(N bit=0 and V bit=0)after the CMP subtraction(D1-2),the result has remained positive:the condition as not been met. The conditions EQ and NE are quite important for other uses,as well.For instance,they can be used to determine if particular bits in a data word are set,by writing the following sequence... ... AND #%00001111,D1 ;masks bits out BEQ SMALLER ;branches when none of the four ; ;lower bits is set CMP #%00001111,D1 BEQ ALL ;branches when all four bits set The AND instruction causes all bits of D1 to be compared with the bits of the parameter(in this case #%00001111).If the same bits are set in both bytes,the corresponding bits are also set in the result.If one bit of the pair is cleared,the resulting bit is zero as well.Thus,in the result,the only bits that are set are those bits of the lowest four that were set in D1. The technique is known as masking.In the example above,only the lowest four bits were masked out,which meansthat in the resulting byte,only the lowest four appear in their original condition.All other bits are cleared with the AND operand.Of course you can use any bit combination with this method. If no bit at all is set in the result,the zeroflag is set,thus fullfilling the BEQ condition and branching the program.Otherwise, the next instruction is processed,in which D1 is compared with %00001111.When both are equal,at leastall of the four lowest bits of the original byte have been set,in which case the following BEQ instruction branches. Aside from CMP,the CC and CS conditions can also be used to determine whether a HI bit was pushed out of the data word during data rotation with the ROL and ROR instructions. Before you move on the instruction vocabulary of the MC68000,we'd like to give you another tip: The AssemPro assembler makes it quite easy to try every command in posible situations.Take the CMP command which we've been talking about,for example.To test this command with various values and to receive the results of the comparisons directly via the flags,try the following. Type the following into the Editor. run: cmp $10,d1 bra run end Assemble it,save the resulting code and enter the debugger.After reloading the code you can then single step through the program observing the results the program has on the flags.Try changing the values in the register D1 and see how higher and lower values affect the flag. By the way,using the start command at this time causes it to run forever.Well,at least until reset is hit,which isn't exactly desirable,either... This procedure isn't limited to just the CMP instruction.You can use it to try any other instructions you're interested in. 2.4.The 68000 Instructions. -------------------------- Its about time to explain the MC68000 instructions.You don't have room for an in-depth discussion of each instruction in this book; for that purpose we recommend PROGRAMMING THE 68000 from Sybex by Steve Williams. The following tables show the required parameters and arguments for each instruction.AssemPro have access to built in help tables covering effective addressing modes and many of the Amiga Intuition calls.The following notation is used for arguments: Label a label or address Reg register An address register n Dn data register n Source source operand Dest destination operand address or register #n direct value Here is a short list of the instructions for the MC68000 processor AssemPro owners can simply place the cursor at the beginning of the instruction and press the help key to see the addressing modes allowed: Mnemonic Meaning --------------------------------------------------- Bcc Label conditional branch,depends on condition BRA Label unconditional branch(similar to JMP) BSR Label branch to subprogram.Return address is deposited on stack,RTS causes return to that address. CHK ,Dx check data register for limits,activate the CHK instruction exception. DBcc Reg,Label check condition,decrement and branch JMP Label jump to address(similar to BRA) JSR Label jump to subroutine.Return address is deposited on stack,RTS causes return to that address. NOP no operation RESET reset peripherals(caution!) RTE return from exception RTR return with loading of flags RTS return from subroutine(after BSR and JSR) Scc set a byte to -1 when condition is met STOP stop processing(caution!) TRAP #n jump to an exception TRAPV check overflow flag,the TRAPV exception Here are a few important notes... When a program jumps(JSR)or branches(BSR)to subroutine,the return address to which the program is to return is placed on the stack. At the RTS instruction,the address is pulled back off the stack, and the program jumps to that point. Lets experiment a little with this procedure.Please enter the following short program: run: pea subprogram ;address on the stack jsr subprogram ;subprogram called move.l (sp)+,d1 ;get a long word from stack ; illegal ;for assemblers without ;debuggers subprogram: move.l (sp),d0 ;return address in D0 rts ;and return end The first instruction,PEA,places the address of the subprogram on the stack.Next,the JSR instruction jumps to the subprogram.The return address,or the address at which the main program is to continue after the completion of the subprogram,is also deposited on the stack at this point. In the subprogram,the long word pointed to by the stack pointer is now loaded into the data register D0.After that,the RTS instruction pulls the return address from the stack,and the program jumps to that address. Back in the main program,the long word which is on the top of the stack,is pulled from the stack and written in D1.Assemblers that do not have the debugging features of AssemPro may need the ILLEGAL instruction so they can break the program and allow you to view the register contents. Assemble the program and load the resulting code into the debugger Single step thru the program and examine the register contents. Here you can see that D0 contains the address at which the program is to continue after the RTS command.Also,D1 contains the address of the subprogram which you can verify by comparing the debugger listing. The STOP and RESET instructions are so powerful that they can only be used in supervisor mode.Even if you do switch to the supervisor mode,you should NOT use these instructions if there is any data in memory that has not been saved and you wish to retain. The TRAP instruction receives a number between 0 and $F,which determines the particular TRAP vector(addresses $0080-$00BF)and thus the corresponding exception routine.Several operating systems for the 68000 utilize this instruction to call operating system functions.You'll deal more with this instruction later. In the short sample program that compared two numbers,the CMP instruction performed an arithmetic function,namely a subtraction. This subtraction could be performed with an actual result as well using the SUB instruction.The counterpart to this is in addition, for which the ADD instruction is used.In 8 bit processors,like the 6502,these arithmetic functions are the only mathematical operations.The MC68000 can also multiply,divide,and perform these operations with a variety of data sizes. Most of the functions require two parameters.For instance the ADD instruction... ADD source,destination where source and destination can be registers or memory addresses. Source can also be a direct value(#n).The result of the opoeration is placed in the destination register or the destination address. This is same for all operation of this type.These instructions can be tried out with the AssemPro assembler.In this case we recommend the use of a register as the destination. Heres an overview of the arithmetic operations with whole numbers: Mnemonic Meaning -------------------------------------------------------------- ADD source,dest binary addition ADDA source,An binary addition to a address register ADDI #n, addition with a constant ADDQ #n, fast addition of a constant which can be only from 1-8 ADDX source,dest addition with transfer in X flag CLR clear an operand CMP source,dest comparison of two operands CMPA ,An comparison with an address register CMPI #n, comparison with a constant CMPM source,dest comparison of two memory operands DIVS source,dest sign-true division of a 32 bit destination by a 16 bit source operand. The result of the division is stored in the LO word of the destination,the remainder in the HI word. DIVU source,dest division without regard to sign,similar to DIVS EXT Dn sign-true expansion to twice original size(width)data unit MULS source,dest sign-true multiplication of two words into one long word MULU source,dest multiplication without regard to sign, similar to MULS NEG negation of an operand(twos complement) NEGX negation of an operand with transfer SUB source,dest binary subtraction SUBA ,An binary subtraction from an address register SUBI #n, subtraction of a constant SUBQ #n, fast subtraction of a 3 bit constant SUBX source,dest subtraction with transfer in X flag TST test an operand and set N and Z flag For the processing of whole numbers,the processor can operate with BCD numbers.These are Binary Coded Decimal numbers,which means that the processor is working with decimals.In this method,each halfbyte contains only numbers from 0 to 9,so that these numbers can be easily processed.For this method,the following instructions are available: Mnemonic Meaning ----------------------------------------------------------------- ABCD source,dest addition of two BCD numbers NBCD source,dest negation of a BCD number(nine complement) SBCD source,dest subtraction of two BCD numbers Again,we recommend that you try this out yourself.Although handling the BCD numbers is relatively easy,it can be rather awkward at first.Be sure that you enter only BCD numbers for source and destination,since the results are not correct otherwise. Next are the logical operations,which you might know from BASIC. With these functions,you can operate on binary numbers bit for bit. Mnemonic Meaning ----------------------------------------------------------------- AND source,dest logic AND ANDI #n, logic AND with a constant EOR source,dest exclusive OR EORI #n, exclusive OR with a constant NOT inversion of an operand OR source,dest logic OR ORI #n, logic OR wuth a constant TAS check a byte and set bit 7 Single bits can also be manipulated by the following set of instructions: Mnemonic Meaning ---------------------------------------------------------------- BCHG #n, change bit n(0 is changed to 1 and vice versa) BCLR #n, clear bit n BSET #n, set bit n BTST #n, test bit n,result is displayed in Z flag These instructions are particularly important from the manipulation and evaluation of data from peripherals.After all,in this type of data,single bits are often very significant.You'll come across this more in later chapters. The processor can also shift and rotate an operand within itself ('n'indicates a register,'#'indicates a direct value which specifies the number of shiftings)... Mnemonic Meaning ---------------------------------------------------------------- AS n, arithmetic shift to the left(*2^n) ASR n, arithmetic shift to the right(/2^n) LSL n, logic shift to the left LSR n, logic shift to the right ROL n, rotation left ROR n, rotation right ROXL n, rotation left with transfer in X flag ROXR n, rotation right with transfer in X flag All these instructions allow you to shift a byte,a word or a long word to the left or right.Its not too surprising that this is the equivalentof multipling(dividing)the number by a power of 2.Here's a little example to demonstrate why Lets take a byte containing the value 16 as an example.In binary, it looks like this: %00010000 =16 Now,if you shift the byte to the left by inserting a 0 at the right,you'll get the following result... %00010000 shifted to the left equals %00100000 =32,in effect 16*2 Repeated shifting results in repeated doubling of the number.Thus if you shift the number n times,the number is multiplied by 2^n. The same goes for shifting to the right.However,this operation as a slight quirk:here's a sample byte with the value 5: %00000101 =5,shifted once to the right equals %00000010 =2 The answer in this case is not 2.5 as you might expect.The result such a division is always a whole number,since any decimal places are discarded.If you use the DIV instruction instead of shifting, you'll retain the digits to the right of the decimal point.However shifting is somewhat faster,and shifting can also receive long words as results. After explaining the principle of shifting,you still need to know why more than two instructions are required for the procedure.Well this is because there are several different types of shifting. First,you must differentiate between shifting and rotating.In shifting,the bit that is added to the left or the right side is always a zero.In rotating,it is always a specific value that is inserted.This means that with the ROR or the ROL instructions,the bit that is taken out on one side is the one that is inserted on the other.With the ROXR and the ROXL instructions this bit takes a slight detour to the X flag.Thus,the content of the flag is inserted into the new bit,while the old bit is loaded into the flag. Shifting as well,has two variations:arithmetic and logical shifting.You've already dealt with logical shifting.In this variation,the inserted bit is always a zero,and the extracted bit is deposited in the C flag and in the X flag. Although the highest bit,which always represents the sign,is shifted in arithmetic shifting,the sign is still retained by ASR. This has the advantage that when these instructions are used for division,the operation retains the correct sign(-10/2 equals-5). However,should an overflow or underflow cause the sign to change, this change is noted in the V flag,which always indicates a change in sign.With logical shifting this flag is always cleared. Now to the instructions that allow you to move data.These are actually the most important instructions for any processor,for how else could you process data? Mnemonic Meaning ------------------------------------------------------------------ EXG Rn,Rn exchange of two register contents(don't confuse with swap) LEA ,An load an effective address in address register An LINK An,#n build stack range MOVE source,dest carry value over from source to dest MOVE SR, transfer the status register contents MOVE ,SR transfer the status register contents MOVE ,CCR load flags MOVE USP, transfer the user stack point MOVE ,USP transfer the user stack point MOVEA ,An transfer a value to the address register An MOVEM Regs, transfer several registers at once MOVEM ,Regs transfer several registers at once MOVEP source,dest transfer data to peripherals MOVEQ #n,Dn quickly transfer a 8 bit constant to the data register Dn PEA deposit an address on the stack SWAP Dn swap the halves of the register(the upper 16 bits with the lower) UNLK An unlink the stack The LEA or PEA instructions are often used to deposit addresses in an address register or on the stack.The instruction LEA label,A0 loads the address of the label'label' into the address register A0.In practice,this corresponds to MOVE.L #label,A0 which is equivalent to PEA label All these instructions deposit the address of 'label' on the stack The following instruction also does this: MOVE.L #label,-(SP) The LEA instruction becomes much more interesting when the label is replaced by indirect addressing.Here's an example: LEA 1(A0,D0),A1 The address that's produced by the addition of 1(direct value offset)+A0+D0 is located in A1.To duplicate this instruction with MOVE would be quite cumbersome.Take a look: MOVE.L A0,A1 ADD.L D0,A1 ADDQ.L #1,A1 As you can see,the LEA instruction offers you quite some interesting possibilities. Those are all the instructions of the MC68000.Through their combination using the diverse methods of addressing,you can create a great number of different instructions,in order to make a program as efficent as possible. The following table is an overview of all MC68000 instructions along with their possible addressing types and the influence of flags.The following abbreviations are used: x=legal s=source only d=destination only -=not effected 0=cleared *=modified accordingly 1=set u=undermined P=privileged Mnemonic 1 2 3 4 5 6 7 8 9 10 11 12 X N Z V C P ----------------------------------------------------------------- ABCD x ADD s s x x x x x x x s s s * * * * * ADDA x x x x x x x x x x x x - - - - - ADDI x x x x x x x x * * * * * ADDQ x x x x x x x x x * * * * * ADDX x x * * * * * AND s x x x x x x x s s s - * * 0 0 ANDI x x x x x x x x - * * 0 0 ASL, ASR x x x x x x x x * * * * * Bcc - - - - - BCHG x x x x x x x x - - * - - BCLR x x x x x x x x - - * - - BRA - - - - - BSET x x x x x x x x - - * - - BSR - - - - - BTST x x x x x x x x z x x - - * - - CHK x x x x x x x x x x x - * u u u CLR x x x x x x x x - 0 1 0 0 CMP x x x x x x x x x x x x - * * * * CMPA x x x x x x x x x x x x - * * * * CMPI x x x x x x x x - * * * * CMPM x x x x x x x - * * * cpGEN - - - - - DBcc - - - - - DIVS x x x x x x x x x x x - * * * 0 DIVU x x x x x x x x x x x - * * * 0 EOR x x x x x x x x - * * 0 0 EORI x x x x x x x x - * * 0 0 EORI CCR * * * * * EORI SR * * * * * EXG - - - - - EXT - * * 0 0 EXTB - * * 0 0 ILLEGAL - - - - - JMP x x x x x x x - - - - - JSR x x x x x x x - - - - - LEA x x x x x x x - - - - - LINK x - - - - - LSL, LSR x x x x x x x * * * 0 * MOVE x s x x x x x x x s s s - * * 0 0 MOVEA x x x x x x x x x x x x - - - - - MOVE to CCR x x x x x x x x x x x * * * * * MOVE from SR x x x x x x x x - - - - - P MOVE to SR x x x x x x x x x x x * * * * * P MOVE USP x - - - - - P MOVEM x s d x x x x s s - - - - - MOVEP s d - - - - - MOVEQ d - * * 0 0 MULS x x x x x x x x x x x - * * 0 0 MULU x x x x x x x x x x x - * * 0 0 NBCD x x x x x x x x * u * u * NEG x x x x x x x x * * * * * NEGX x x x x x x x x * * * * * NOP - - - - - NOT x x x x x x x x - * * 0 0 OR s x x x x x x x s s s - * * 0 0 ORI x x x x x x x x - * * 0 0 PEA x x x x x x x - - - - - RESET - - - - - P ROL, ROR x x x x x x x - * * 0 * ROXL, ROXR x x x x x x x - * * 0 * RTE - - - - - P RTR * * * * * RTS - - - - - SBCD x x * u * u * Scc x x x x x x x x - - - - - STOP x - - - - - SUB s s x x x x x x x s s s * * * * * SUBA x x x x x x x x x x x x - - - - - SUBI x x x x x x x x * * * * * SUBQ x x x x x x x x x * * * * * SUBX x x * * * * * SWAP x - * * 0 0 TAS x x x x x x x x - * * 0 0 TRAP x - - - - - TRAPV - - - - - TST x x x x x x x x - * * 0 0 UNLK x - - - - - Chapter 3. --------- 3.Working With Assemblers. ------------------------- The instructions that you've learned so far are incomprehensible to the MC68000 processor.The letters MOVE mean absolutely nothing to the processor-it needs the instructions in binary form.Every instruction must be coded in a word-which normally takes a lot of work. An assembler does this work for you.An assembler is a program that translates the instructions from text into the coresponding binary instructions.The text that is translated is called Mnemonic or Memcode.Its a lot easier working with text instructions-or does $4280 mean more to you than CLR.L D0? This chapter is about working with assemblers.We'll describe the following three: ASSEM; This is the assembler from the Amiga's development package.This assembler is quite powerful,but it is clearly inferior to its two fellow compilers in some areas. AssemPro; This is the Abacus assembler.It has a debugger in addition to the assembler.This lets you test and correct programs.In our opinion, it is the best one to use for writing and testing practice programs.For this reason,we wrote the programs in this book with this assembler. KUMA-SEKA; This is a popular assembler which also has a debugger. All assemblers perform a similar task-they translate memcode,so that you can write a runable program to disk.To test the program directly,you need a debugger which is something Assem doesn't have. 3.1.The Development Assembler. ----------------------------- This assembler is a plain disk assembler.That means that it can only assemble text files that are on disk and write the result back to disk.You can't make direct input or test run the new program. You can call ASSEM from the CLI by typing ASSEM followed by parameters that specify what you wish the assembler to do. In the simplest case,you call it like this: ASSEM Source -O Destination Source is the filename of the file containing the program text. Destination is the name of the file that contains the results of assembling after the process is over.The "-O"means that the following name is used for the object file. There are several other parameters that can be passed.These are written with their option(ie-O),so that the assembler knows what to do with the file that you've told it to use.The following possible options must be followed by a filename. -O Object file -V Error messages that occur during assembling are written to a file.If this isn't given,the error messages appear in the CLI window. -L The output of the assembled program lines are sent to this file.You can also use"PRT:"to have it printed. -H This file is read in at the beginning of the assembled file and assembled along with it. -E A file is created that contains lines which have EQU instructions. -C This option isn't followed by a filename but by another option.You can also use OPT to do this.The following options are available: OPT S A symbol table is created which contains all the labels and their values. OPT X A cross reference list is created(where labels are used). OPT W A number must follow this option.It sets the ammount of workspace to be reserved. The assembler creates an object file.This is not runnable.To make it runnable,you need to call the linker,ALINK.This program can link several assembled or compiled object files together to make a runnable program.In the simplest case,you enter the following instruction in the CLI: ALINK Source TO Destination Source is the object file produced by the assembler.Destination is the name of the program.It can be started directly. 3.2.AssemPro. ------------ Abacus's AssemPro is a package which combines editor,assembler and debugger in an easy to use package. The AssemPro Program is divided into several windows-one for the assembler,the editor,the debugger and several help functions. Producing a program is very easy: 1) Write the program with the editor and then store it to disk. 2) Start the assembler,so that the program is translated. 3) If desired,start the debugger,load the program and test it. Within the debugger you can work through parts of the program or even through single commands.As after each one of these steps the debugger shows you the state of the registers and flags in the status register,you can easily try the programs presented in this book. You need to load AssemPro only once when working with machine language programs.Thus you don't need to save back and to between editor,assembler,linker and debugger. AssemPro has an especially interesting function:the reassembler. With this debugger function you are able to convert runnable programs into the source text of the program.Once you have made the source text,you can edit the program using the editor and assemble it again.AssemPro is equipped with functions other assemblers miss.There are however,some differences you should know about.As many programs you see were written for the K-SEKA,be aware of one difference:the EVEN command.AssemPro uses the ALIGN instruction. Note,that when entering and assembling one of the programs in AssemPro you must make sure that you place an END directive at the end of the source text. The following is an introduction into working with AssemPro and the programs in this book. Start AssemPro normally,next click on the editor window and start typing in your program.If the program is on disk already,load it by selecting the appropriate menu or by using the key combination right key and .To do this you only need to ckick on the filename in the displayed requester and click on the OK gadget. Once you have typed in or loaded the program into the editor,you can assemble it.It is best to save your source before assembling. You assemble your program by clicking on the assembler window displayed above the editor window and pressing and .You can then choose how to locate your program in the memory.Remember that data used by the co-processors must be located in CHIP RAM. By clicking OK you start the assembler process.If you additionally select "breakable",you can cancel the process by pressing both shift keys.If any error occurs during assembling,AssemPro uses a window to tell you this.Use this window to correct the error and continue with "Save and try again". Now the runnable program is located in the Amiga's memory.Use the menu item "Save as"to save it on disk.If you want to store it on RAM disk,click the given filename and enter RAM: in front of this name.In addition you can click on the menu item "ICON"and choose if you only want the program itself on disk but the icon too.Use this icon to start the program at a later time from Workbench. To test-run the program,you move the debugger window to the foreground of the screen(for instance by clicking on the back gadget).Use "Load"in the debugger menu or to call the select file window,where you select the saved program.The program is then loaded into the memory and its shown disassembled. The highlighted line(orange)represents the current state of the program counter.This is the line where the processor reads its next instruction,provided you tell the processor so.There are three ways to do so. The first one is to start the program with "Start".This alternative does not enable you to stop the program if anything goes wrong. The second possibility,"Start breakable"is better in this respect. After the program starts,it continuously displays the registers contents on the left side of the window.In addition to that you can cancel the process by pressing .Note that this only works if your program doesn't use the key itself. The third possibility enables you to only partly run your program. You can do this by stepping through the program or by placing breakpoints throughout the program.You place these by clicking on the desired address and then pressing ."BREAKPOINT"is displayed where the command was displayed before.If you start the program now,it stops whenever it comes across any breakpoints. You can start a small part of the program by moving the mouse pointer to the orange line,clicking the left button and holding it down while you drag the mouse pointer downward.If you release the button,the processor works through this part of the program, stopping at the line,where you positioned the mouse pointer.This is a very useful method to step by step test a program. AssemPro as another helpful window:the Table.This window lists the valid address methods for instructions and the parameters of Amiga functions.This is extremely helpful whenever you are not sure about one of the instructions. 3.3.The K-SEKA Assembler. ------------------------ The SEKA assembler,from KUMA,has a simple text editor and a debugger in addition to the assembler.This program is controlled by simple instructions and it is easy to use.It is also multi- functional and quick,so it is great for small test and example programs.You can use it to write bigger programs once you've got use to the editor.Now lets look at the editor. To load a program as source code(text)into the editor,enter"r" (read).The program asks you for the name of the file with the ""prompt.You then enter the name of the text file.If you created the file with SEKA,the file is stored on disk with".s" on the end of its name.You don't need to include the".s"when you load the file.Thats taken care of automatically.("s"stands for source.) You can store programs you've just written or modified by using the"w"instruction.The program asks you for the name.If you enter "Test",the file is written to the disk with"Test.s"as its name. This is a normal text file in ASCII format. There are two ways to enter or change a programs:using the line editor or the screen editor.You can enter the second by hitting the key.The upper screen section is then reserved for the editor.You can move with the cursor keys and change the text easily.The lines that you enter are inserted into the existing text and automatically numbered.By hitting the key again,you leave the screen editor. There's really not much to say about this editor.It's really just for simple insertions and changes.Other functions are called in normal instruction mode,the mode in which">"is the input prompt. The following instructions are available to you for text editing (stands for a number.The meaning of the instructions is in parenthesis.) Instruction Function ---------------------------------------------------------------- t(Target) Puts the cursor on the highest line in the text. t Puts the cursor on line n. b(Bottom) Puts the cursor on the last line in the text. u(Up) Go up one line. u Go up n lines. d(Down) Go down one line. d Go down n lines. z(Zap) Deletes the current line. z Deletes n lines starting at the cursor line. e(Edit) Lets you edit the current line(and only that line). e Edit from line n. ftext(Find) Searches for the text entered starting at the current line.The case of a letter makes a difference,so make sure to enter it correctly. Blanks that appear after the f are looked for as well! f Continues searching beyond the text that was previously given. i(Insert) Starts the line editor.Now you can enter a program line by line.However,you can't use the cursor to move into another line.Line numbers are generated automatically.The lines that follow are moved down,not erased. ks(Kill Source) The source text is deleted if you answer"y" when the program asks if you are sure.Otherwise nothing happens. o(Old) Cancels the "ks"function and saves the old text p(Print) Prints the current line. p Prints n lines starting at cursor line. Those are the K-SEKA's editor functions.In combination with the screen editor,they allow for simple text editing.You can,for example,delete the current line(and other lines)while working in the screen editor by hitting to get into instruction mode and then entering"z"(or "z"). If you'd like to edit all lines that contain "trap",for example, you can do the following: -Jump to the beginning of the text using "t" -Search for a "trap"instruction by entering "ftrap" in the first line. -Press and edit the line. -Press again to get into instruction mode. -Search using "f",,etc.until you get to the end of the text. This sounds very clumsy,but in practise it works quite well and goes quickly.Experiment with the editor bit,so you can get use to it. Now here are the instructions for working with disks: Instruction Function ----------------------------------------------------------------- v(View files) Look at the disk's directory.You can also include the disk drive or subdirectory that interests you.For example,"vc"causes the "c"subdirectory to be listed and makes it the current directory. kf(Kill file) The program asks for the name of the file. The file is deleted(and you aren't asked if your sure either-so be careful). r(Read) After inputting this instruction,you'll be asked which file to load(FILENAME>).The file that you specify is then loaded.If only "r"is entered,a text file is loaded in the editor. ri(Read Image) Loads a file into memory.After you've entered the filename,SEKA asks for the address the file should begin at in memory (BEGIN>)and the highest address that should be used for the file(END>). rx(Read from Auxillary) This works just like the "ri"function except that it reads from the serial port instead of from disk(You don't need a file name). rl(Read Link file) This instruction reads in a SEKA created link file.First you'll be asked if you are sure,because the text buffer is erased when the link file is loaded. w(Write) After entering this instruction,you'll be asked for the name of the file the text should be written to.A".s"is automatically appended to the name,so that it can be recognized as a SEKA file. wi(Write Image) Stores a block of memory to disk after the name,beginning and end are entered. wx(Write to Auxillary) This is similar to"wi";the only difference is that the output is to the serial inter- face. wl(Write Link file) Asks for the name and then stores a link file that was assembled with the"I"option to disk.If this isn't available,the message "* * Link option not specified" appears. Once you've typed in or loaded a program,you can call the assembler and have the program translated.Just enter"a"to do so. You'll then be asked which options you want to use.If you enter a ,the program is assembled normally-ie the results of translating a program in memory is stored in memory.Then the program can be executed straight away. You can enter one or more of the following options,however: v The output of the results goes to the screen. p or e goes to the printer with a title line. h The output stops after every page and waits for a key stroke.This is useful for controlling output to the screen or for putting new sheets of paper in the printer. o This option allows the assembler to optimize all possible branch instructions.This allows the program code to be shorter than it would otherwise be.Several messages appear but you can ignore them. l This option causes linkable code to be produced.You can save it with the"wl"instruction and read it with the "rl" instruction. A symbol table is included at the end of the listing if desired. The table contains all labels and their values.It also contains macro names.A macro allows several instructions to be combined in to a single instruction. For example,suppose you wrote a routinethat outputs the text that register A0 points to.Every time you need to use the routine,you must type: lea text,a0 ;pointer to text in A0 bsr pline ;output text You can simplify this by defining a macro for this function.To do this,put the following at the beginning of the program: print:macro ;Macro with the name "Print" lea ?1,a0 ;Parameter in A0 bsr pmsg ;Output text endm ;End of macro Now,you can simply write the following in your program: print text ;Output text This line is replaced using the macro during assembly.The parameter "text"is inserted where "?1"appears in the macro.You can have several parameters in a macro.You give them names like "?2", "?3",etc... You can also decide whether you'd like to see the macros in the output listing of the assembler.This is one of the pseudo-ops that are available in the assembler.The SEKA assembler has the following pseudo-ops: dc Defines one or more data items that should appear in this location in the program.The word length can be specified with .B,.W,or .L-and if this is left off, .B is used.Text can be entered in question marks or apostrophes.For example:dc.b "Hello",10,13,0 blk Reserves a number of bytes,words or long words,depending on whether .B,.W,or .L is chosen.The first parameter specifies the number of words to be reserved.The second (which is optional)is used to fill the memory area.For example:blk.w 10,0 org The parameter that follows the org instruction is the address from which the (absolute) program should be assembled.For example: org $40000 code Causes the program to be assembled in relative mode,the mode in which a program is assembled starting at address 0.The Amiga takes care of the new addressing after the program is loaded. data This means that from here on only data appear.This can be left out. even Makes the current address even by sometimes inserting a fill byte. odd The opposite of even-it makes the address odd. end Assembling ends here. equ or Used for establishing the value of a label = For example: Value=123 or Value:equ 123 list Turns the output on again(after nlist).You can use the following parameters to influence the output: c Macro calls d Macro definitions e Macro expansion of the program x Code expansions For example: list e nlist Turns off output.You can use the same parameters here as with "list". page Causes the printer to execute a page feed,so that you'll start a new page. if The following parameter decides whether you should continue assembling.If it is zero,you won't continue assembling. else If the "if"parameter is zero,you'll begin assembling here. endif End of conditional assembling. macro Start of a macro definition. endm End of macro definition. ?n The text in the macro that is replaced by the nth parameter in the calling line. ?0 Generates a new three digit number for each macro call- this is very useful for local labels. For example: x?0:bsr pmsg illegal Produces an illegal machine language instruction. globl Defines the following label as globel when the "I"option of the assembler is chosen. Once you've assembled your program,the program code is in memory. Using the "h"instruction,you can find out how large the program is and where it is located in memory.The beginning and end address is given in hex and the length in decimal(according to the last executed operations): Work The memory area defined in the beginning Src Text in memory RelC Relocation table of the program RelD Relocation table of the memory area Code Program code produced Data The program's memory area You'll find program in memory at the location given by Code.It's a pain to have to enter this address whenever you want to start the program.It make's good sense to mark the beginning of the program with a label(for example,"run:").You can use the "g"instruction to run the program as follows: g run The"g"(GO)instruction is one of SEKA's debugger instrucions.Heres an overview: x Output all registers. xr Output and change of registers(ie xd0) gn Jump to address n.You`ll be asked for break points,addresses at which the program should be terminate. jn This is similar to the one above-a JSR is used to jump into the program.The program must end with a RTS instruction. qn Output the memory starting at address n.You can also specify the word length.For example: q.w $10000 nn Disassembled output starting at address n. an Direct assembling starting at address n.Direct program instructions are entered. nn Modify the contents of memory starting at address n.Here too the word length can be given.You can terminate input with the key. sn Executes the program instruction that the PC points to.After you enter this instruction,n program steps are executed. f Fill a memory area.You can choose the word width.All the needed parameters are asked for individually. c Copies one memory area to another.All the needed parameters are asked for individually. ? Outputs the value of an expression or a label. For example: ?run+$1000-256 a Sets an instruction sequence that is passed to the program when it starts as if it were started from CLI with this sequence. ! Leaves the SEKA assembler after being asked if your sure. You saw some of the calculations like SEKA can make in the "?" example.You can also use them in programming.The folowing operations work in SEKA: + Addition - Subtraction * Multiplication / Division & Logic AND ! Logic OR ~ EXclusive OR (XOR) These operations can also be combined.You can choose the counting system.A "$"stands for hexadecimal,"@"for octal,and "%"for binary. If these symbols aren`t used,the number is interpreted as a decimal number. Lets go back to the debugger.As mentioned,after entering "g address",you`ll be asked for break points.You can enter up to 16 addresses at which the program halts.If you don`t enter break points,but instead hit ,the program must end with an ILLEGAL instruction.If it ends instead with a RTS,the next return address from the stack is retrieved and jumped to.This is usually address 4 which causes SEKA to come back with "**Illegal Instruction at $000004",but theres no guarantee that it will.Your computor can end up so confused that it can`t function. The SEKA program puts an ILLEGAL instruction in the place specified as break points after saving the contents of these locations.If the processor hits an illegal instruction,it jumps back to the debugger by using the illegal instruction vector that SEKA set up earlier.Then SEKA repairs the modified memory locations and then displays the status line.Here you can find out where the program terminated. Using break points is a good technique for finding errors in the program.You can,for example,put a break point in front of a routine that you`re not sure about and start the program.When the program aborts at this spot,you can go through the routine step by step using the "s"option.Then you can watch what happens to the status line after each instruction and find the mistake. Program errors are called bugs.That`s why the program that finds them is called a debugger. Chapter 4. --------- 4.Our First Programs. -------------------- You`re getting pretty far along in your knowledge of machine language programming.In fact,you`re to the point where you can write programs,and not just programs for demonstration purposes, but ones that serve a real function.We`re assuming that you have the AssemPro assembler and have loaded it. If you`re using a different assembler,a few things must be done differently.We covered those differences already in the chapter on the different assemblers. We`ve written the example programs as subroutines so they can be tried out directly and used later.After assembling the program,you can put the desired values in the register.Then you can either single-step thru the programs or run the larger programs and observe the results in the registers directly.(using the SEKA assembler you can type "j program_name"to start the program.Then you can read the results from the register directly,or use "q address"to read it from memory.) Lets start with an easy example,adding numbers in a table. 4.1.Adding Tables. ----------------- Imagine that you have numbers in memory that you'd like to add. Lets assume that you have five numbers whose length is one word each.You want their sum to be written in register D0.The easiest way to do this is: ;(4.1A) adding1: clr.l D0 ;Erase D0 (=0) move table,d0 ;First entry in D0 add table+2,d0 ;Add second entry add table+4,d0 ;Add third entry add table+6,d0 ;Add fourth entry add table+8,d0 ;add fifth entry rts ;Return to main program table: dc.w 2,4,6,8,10, end Try out the program using the debugger by single stepping thru the program until you get to the RTS instruction(left Amiga T).(SEKA owners use "j adding1").You see that data register D0 really contains the sum of the values. The method above only reads and adds numbers from a particular set of addresses.The Amigas processor has lots of different sorts of addressing modes that give us a shorter and more elegant solution. Lets add a variable to the address of the table,so that the program can add different tables. Lets put the addresses of the table in an address register(for example, A0)instead.This register can be used as a pointer to the table.You must use move.l since only long words are relocatable.By using a pointer to a table you can use indirect addressing.You can change the expression "table+x" to"x(A0)". ;(4.1B) adding1: clr.l D0 ;Erase D0 (=0) move.l #table,a0 ;Put table addresses in A0 move 0(a0),d0 ;Put first entry in d0 add 2(a0),d0 ;Add second entry add 4(a0),d0 ;Add third entry add 6(a0),d0 ;Add forth entry add 8(a0),d0 ;Add fifth entry rts ;Return to main program] table: dc.w 2,4,6,8,10 end Assemble this program,load it into the debugger.Then single step (left Amiga T)thru this program and you'll see that this program adds five numbers in order just like the last one.The reason you used a step size of two for the ofset is that words are two bytes long.AssemPro also defaults to relocate code so that you must move #table as a long word. Lets improve the program more by using "(a0)+"instead of "x(a)". This way,every time you access elements of the table,the address register A0 is automatically incremented by the number of bytes that are read(in this case two).The difference between this and the last example is that here the registers contents are modified. The pointer is to the next unused byte or word in memory. Lets make it even better.Lets make the number of words to be added to a variable.You'll pass the number in register D1.Now you need to do a different sort of programming,since you can't do it with the old methods. Lets use a loop.You need to add D1 words.You can use(a0)+ as the addressing method(address register indirect with post increment), since this automatically gets you to the next word. Now for the loop.You'll have D1 decremented by one every time the contents of the pointer are added.If D1 is zero,then you're done. Otherwise,you need another addition.The program looks like this: ;(4.1C) adding2: clr.l d0 ;Erase D0 move.l #table,a0 ;Put table addresses in A0 move #$5,d1 ;Put number of entries in D1 loop: ;Label for loop beginning add (a0)+,d0 ;Add a word subq #1,d1 ;Decrement counter bne loop ;Continue if non-zero rts ;Else done table: dc.w 2,4,6,8,10 end Lets take a close look at this program.Load the pointer A0 with the addresses of the data and the counter D1 with the number of elements.Then you can single step thru the program and watch the results.Make sure not to run the final command,the RTS command, because otherwise a return address is popped from the stack,and the results of this are unpredictable.(SEKA owners can use"x pc" to point the program counter to "adding2".You can then step thru the program by using the "s"command and watch the results). To finish up this example,your assigning a little homework.Write the program so that it adds single bytes or long words.Try to write a program that takes the first value in a table and subtracts the following values.For example,the table table: dc.w 50,8,4,6 should return the value 50-8-4-6, ie 32 ($20). 4.2.Sorting a Table. ------------------- Lets keep working with tables.You don't want to just read data from one this time.You want to change it.You'll assort the table in assending order. You need to decide how to do the sorting.The simplest method is to do the following. Compare the first and the second value.If the second value is larger than the first one,things are OK so far.Do the next step, compare the second and third values,and so on.If you come to the final pair and in each case the preceding value was smaller than the following value,then the sorting is done(it was unnescessary). If you find a pair where the second value is smaller than the first,the two values are exchanged.You then get a flag(here let's use a register)that is checked once you're done going thru the table.If it is set,the table probably isn't completely sorted.You then erase the flag and start again from the beginning.If the flag is still zero at the end,the sorting is complete. Now let's write a program to do this.First let's figure out the variables you need.You'll use registers for the variables.You need a pointer to the table you're sorting(A0),a counter(D0)and a flag (D1).While the program is running,change these values,so you'll need two more registers to store the starting values(address and the number of the table entries).You'll use A1 and D2. Let's start writing the program,each section will be written and then explained.Then the complete program will be given.You put the tables address in A1 and the number of entries in D2. ;(4.2A) part of sort routine sort: ;Start address of the program move.l #table,a1 ;Load pointer with address move.l a1,a0 ;Copy pointer to working register move.l #5,d2 ;Number in the counter move.l d2,d0 ;Copy number of elements subq #2,d0 ;Correct conter value clr d1 ;Erase flag table: dc.w 3,6,9,5 end Now the preparations are complete.The pointer and the counter are ready and the flag is cleared.The counter is decremented by two because you want to use the DBRA command(take one off)and only X-1 comparrisons are needed for X numbers(take off one more). Next let's write the loop that compares the values.You compare one word with another.It looks like this: loop: move 2(a0),d3 ;Next value in register D3 cmp (a0),d3 ;Compare values You need to use register D3 because CMP (A0),2(A0) isn't a legal choice.If the second value is greater than or equal to the first value,you can skip an exchange. bcc noswap ;Branch if greater than or equal ;to Now you need to do the exchanging(unfortunatly you can't use EXC 2(a0),(a0) since this form of addressing does not exist). doswap: move (a0),d1 ;Save first valus move 2(a0),(a0) ;Copy second into first word move d1,2(a0) ;Move first into second moveq #1,d1 ;Set flag noswap: Now increment the counter and continue with the next pair.You do this until the counter is negative. addq.l #2,a0 ;Pointer+2 dbra d0,loop ;Continuing looping until the end Now you'll see if the flag is set.You start again at the beginning if it is. tst d1 ;Test flag bne sort ;Not finished sorting yet! rts ;Otherwise done.Return If the flag is zero,you're done and the subroutine ends.You jump back to the main program using the RTS command. Now a quick overview of the complete program. ;(4.2B) sort: ;Start address of the program move.l #table,a1 ;Load pointer with address move.l a1,a0 ;Copy pointer to working register move.l #5,d2 ;Number in the counter move.l d2,d0 ;Copy number of elements subq #2,d0 ;Correct counter value clr d1 ;Erase flag loop: move 2(a0),d3 ;Next value in register D3 cmp (a0),d3 ;Compare values bcc noswap ;Branch if greater than or equal to doswap: move (a0),d1 ;Save first value move 2(a0),(a0) ;Copy second into first word move d1,2(a0) ;Move first into second moveq #1,d1 ;Set flag noswap: addq.l #2,a0 ;Pointer+2 dbra do,loop ;Continue looping until the end tst d1 ;Test flag bne sort ;Not finished sorting yet! rts ;Otherwise done.Return table: dc.w 10,8,6,4,2 ;When finished acceding end To test this subroutine,assemble the routine with AssemPro,save it and then load it into the debugger.The table is directly after the RTS,notice its order.Set a breakpoint at the RTS,select the address with the mouse and press left-Amiga-B sets a breakpoint in AssemPro.Start the program the redisplay the screen by selecting "Parameter-Display-Dissassem-bled"and examine the order of the numbers in the table,they should now be ascending order. You use several registers in this example for storing values. Usually in machine language programming your subroutines cannot change any register or can only change certain registers.For this reason,there is a machine language command to push several registers onto the stack at the same time.This is the MOVEM ("MOVE multiple")command.If you insert this command twice in your program then you can have the registers return to the main program with the values they had when the subroutine was called.To do this,you need one more label.Let's call it"start";the subroutine is started from here. start: movem.l d0-d7/a0-a6,-(sp) ;save registers sort: etc... ... ... bne sort ;not finished sorting yet! movem.l (sp)+,d0-d7/a0-a6 ;retrieve registers rts ;finished The powerful command moves several registers at the same time.You can specify which registers should be moved.If you want to move the D1,D2,D3,D7,A2 and A3 registers,just write movem.l d1-d3/d7/a2-a3,-(sp) Before you quit sorting,do one little homework assignment.Modify the program,so that it sorts the elements in descending order. 4.3.Converting Number Systems. ----------------------------- As we mentioned in the chapter on number systems,converting numbers from one base to another can be rather difficult.There is another form of numeric representation-as a string that can be entered via the keyboard or output on the screen. You want to look at some of the many conversions possible and write programs to handle the task.You'll start by converting a hex number into a string using binary numbers and then print the value in hex. 4.3.1.Converting Hex To ASCII. ----------------------------- First you need to set the start and finish conditions.In this example,let's assume that data register D1 contains a long word that should be converted into a 8-digit long string of ASCII characters.You'll write it to a particular memory location so that you can output it later. The advantage of using hex instead of decimal is pretty clear in this example.To find out the hexadecimal digit for a particular spot in the number,you just need to take the corresponting 4 bits (half byte)and do some work on it.A half byte(also called a nibble)contains one hex digit. You'll work on a half byte in D2.To convert this to a printable character,you need to use the correct ASCII code.The codes of the 16 characters that are used as hex digits are the following: 0 1 2 3 4 5 6 7 8 9 A B C D E F $30 $31 $32 $33 $34 $35 $36 $37 $38 $39 $41 $42 $43 $44 $45 $46 To convert the digits 0-9,you just need to add $30.For the letters A-F that correspond to the values 10-15,you need to add $37.The program to evaluate a half byte must make a destinction between values between 0 and 9 and those between A and F and add either $30 or $37. Now let's write a machine language subroutine that you'll call for each digit in the long words hex representation. nibble: and #$0f,d2 ;just keep low byte add #$30,d2 ;add $30 cmp #$3a,d2 ;was it a digit? bcs ok ;yes:done add #7,d2 ;else add 7 ok: rts ;done This routine converts the nibble in D2 to an ASCII character that corresponds to the hex value of the nibble.To convert an entire byte,you need to call the routine twice.Here is a program to do this.The program assumes that A0 contains the address of the buffer that the characters are to be put in and that D1 contains the byte that is converted. ;(4.3.1a) bin-hex ; ;your program lea buffer,a0 ;pointer to buffer move #$4a,d1 ;byte to be converted(example) bsr byte ;and convert rts ; ... ;more of your program byte: move d1,d2 ;move value into d2 lsr #4,d2 ;move upper nibble into lower nibble bsr nibble ;convert d2 move.b d2,(a0)+ ;put character into buffer move d1,d2 ;value in d2 bsr nibble ;convert lower nibble move.b d2,(a0)+ ;and put it in buffer rts ;done nibble: and #$0f,d2 ;just keep low byte add #$30,d2 ;add $30 cmp #$3a,d2 ;was it a digit? bcs ok ;yes:done add #7,d2 ;else add 7 ok: rts ;done buffer: blk.b 9,0 ;space for long word data end To test this subroutine,use AssemPro to assemble the routine,save the program and load it intoi the debugger.Next set a breakpoint at the first RTS,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys. Start the program and watch the contents of D2,it is first $34 (ASCII 4)and finally $41(ASCII A).Select "Parameter-Display-HEX- Dump"and you'll see that 4A has been moved into the buffer. This is how the routine operates.First,you move the value that you wish to convert into D2.Then you shift the register four times to the right to move the upper nibble into the lower four bits.After the subroutine call,you use "move.b d2,(a0)+"to put the HI nibble in the buffer.Then the original byte is put in D2 again.It is converted.This gives us the LO nibble as an ASCII character in D2. You put this in the next byte of the buffer. The buffer is long enough to hold a long word in characters and closing the null byte.The null byte is usually required by screen output routines.Screen output will be discussed in a later chapter.Now let's worry about converting a long word. When converting a long word,you need to be sure to deal with the nibbles in the right order.Before calling the "nibble"routine for the first time,you need to move the upper nibble into the lower 4 bits of the long word.You need to do this without losing anything. The LSR command isn't very good for this application.If you use it you'll lose bits.Its better to use the rotation commands like ROR or ROL,since they move the bits that are shifted out,back in on the other side. If you shift the original long word in D1 four times to the left, the upper four bits are shifted into the lower four bits.Now you can use our "nibble"routine to evaluate it and then put the resulting ASCII character in the buffer.You repeat this eight times and the whole long word has been converted.You even have D1 looking exactly the way it did before the conversion process began ;(4.3.1B) bin-hex-2 hexlong: lea buffer,a0 ;pointer to the buffer move.l #$12345678,d1 ;data to convert move #7,d3 ;counter for the nibbles:8-1 loop: rol #4,d1 ;move upper nibble into lower move d1,d2 ;write in d2 bsr nibble ;and convert it move.b d2,(a0)+ ;character in buffer dbra d3,loop ;repeat 8 times rts ;finished! nibble: and #$0f,d2 ;just keep low byte add #$30,d2 ;add $30 cmp #$3a,d2 ;was it a digit? bcs ok ;yes:done add #7,d2 ;else add 7 ok: rts ;done buffer: blk.b 9,0 ;space for long word,null byte end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the first RTS,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.Start the program and when it is finished redisplay the output by selecting "Parameter-Display-HEX-dump"so you can examine the new buffer contents. You'll find that there's an error in the program-the buffer contains the digits "56785678"instead of "12345678".Try to find the error. Have you found it?This is the sort of error that causes you to start pulling your hair out.This sort is hard to find.The assembler assumes that the rotation operation should be done on a word,because the ".l"was left off.As a result,only the lower word of D1 was rotated-so you get the same value twice.If you change the "rol.l",things work just right. The error shows how easy it is to convert the program above into one that converts four digit hex numbers into ASCII characters. Just leave off the ".l"on the "rol"command and change the counter from seven to three.The program is done. Now for a little homework:change the program so that it can handle six digit hex numbers(D1 doesn't nescessarily have to stay the same...)! Now lets look at a different conversion problem:converting a four digit decimal number. 4.3.2.Converting Decimal To ASCII. --------------------------------- It's not quite as easy to convert decimal as hex.You can't group the bits to form individual digits.You need to use another method. Lets look at how a decimal number is constructed.In a four digit number,the highest place is in the thousands place,the next is the hundreds place,etc... If you have the value in a register and divide by 1000,you'll get the value that goes in the highest place in the decimal number. Since the machine language command DIV not only gives us the result of the division but also gives us the remainder,you can work out the remainder quite easily.You divide the remainder by 100 to find the hundreds place,divide the remainder by 10 and get the tens place,and the final remainder is the ones place. This isn't so hard after all!Heres the program that follows the steps above to fill the buffer with D1's ASCII value. main: lea buffer,a0 ;pointer to the buffer move #1234,d1 ;number to convert jsr deci_4 ;test subroutine illegal ;room for breakpoint deci_4: ;subroutine-four digit numbers divu #1000,d1 ;divide by 1000 bsr digit ;evaluate result-move remainder divu #100,d1 ;divide by 100 bsr digit ;evaluate result and move divu #10,d1 ;divide by 10 bsr digit ;evaluate result-move remainder ;evaluate the remainder directly digit: add #$30,d1 ;convert result into ASCII move.b d1,(a0)+ ;move it into buffer clr d1 ;erase lower word swap d1 ;move the remainder down rts ;return buffer:blk.b 5,0 ;reserve bytes for result end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the illegal instruction.To set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.This breakpoint stops the program.Start the program and when it is finished redisplay the output by selecting"Parameter-Display -HEX-dump"so you can examine the ASCII values now in the buffer. You use a little trick in this program that is typical for machine language programming.After calling"digit"three times from the sub- routine"deci_4",you go right into the"digit"subroutine.You don't use a BSR or JSR command.Once the processor hits the RTS command, it returns to the main program,not the "deci_4"subroutine.Doing this,you save a fourth "bsr digit"command and an "rts"command for the "deci_4"routine. Try the program out.Make sure that you use values that are smaller than 9999,because otherwise strange things can happen. Now let's reverse what you've been doing and convert strings into binary numbers. 4.3.3.Converting ASCII To Hex. ----------------------------- In a string,each hex digit represents a half byte.You just need to write a program that exactly reverses what the hex conversion program did. You have two choices 1. The number of hex digits is known in advance 2. The number is unknown The first is easier to program,but has the disadvantage that if, you assume the strings are four digits in length and want to enter the value 1,you must enter 0001.That is rather awkward,so you'll use the second method. Let's convert a single digit first.You'll pass a pointer to this digit in address register A0.You want the binary value to come back in data register D0. The program looks like this: move.l #string,a0 ;this example jsr nibblein ;test routine nop ;set breakpoint here nibblein: ;*convert the nibble from (A0) clr.l d0 ;erase D0 move.b (a0)+,d0 ;get digit,increment A0 sub #'A',d0 ;subtract $41 bcc ischar ;no problem:in the range A-F add #7,d0 ;else correct value ischar: add #10,d0 ;correct value rts string:dc.b 'B',0 ;character to convert end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the first NOP,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.Start the program and watch the contents of D0. Let's see how the program works.A0 points to a memory location that contains the character "B"that is represented by the ASCII value $42.This number is loaded into D0 right after this register is erased. After subtracting $41,you end up with the value $1.Now you're almost done.Before returning to the main program,you add 10 to get the correct value 11,$B. If the buffer has a digit in it,the subtraction causes the register to become negative.The C flag is set.Let's take the digit 5 as an example. The ASCII value of 5 is $35.After subtracting $41,you end up with -12 and the C flag is set.In this case,you won't branch with the BCC command.Instead you'll add 7 to get -5.Then 10 is added,and you end up with 5.Done! The routine as a disadvantage.If an illegal character is given,one that doesn't represent a hex digit,you'll get some nonsense result Let's ignore error checking for the moment though. Let's go on to multi-digit hex numbers.The first digit that you convert has the highest value and thus represents the highest nibble.To allow for this and to allow for an arbitrarily long number(actually not arbitrarily long,the number should fit in a long word-so it can only be eight digits long),you'll use a trick. Take a look at the whole program.It handles the calculations and puts the result in D1.It assumes that A0 is a pointer to a string and that this string is ended by null byte. hexin: ;converting a hex number clr.l d1 ;first erase D1 move.l #string,a0 ;address of the string in A0 jsr hexinloop ;test subroutine nop ;set breakpoint here hexinloop: tst.b (a0) ;test digit beq hexinok ;zero,then done bsr nibblein ;convert digit lsl.l #4,d1 ;shift result or.b d0,d1 ;insert nibble bra hexinloop ;and continue hexinok: rts nibblein: clr.l d0 ;convert the nibble from (A0) move.b (a0)+,d0 ;get digit,increment A0 sub #'A',d0 ;subtract $41 bcc ischar ;no problem:in range A-F add #7,d0 ;else correct value ischar: add #10,d0 ;correct value rts string:DC.B "56789ABC',00 ;eight digit string,null byte ;to be converted end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the NOP,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.Start the program and watch the contents of D1,the hex value is placed in this register. The trick is to shift left four times,to shift one nibble.In this way,the place of the last digit is incremented by one and there is room for the nibble that comes back from the "nibblein"routine.The program uses the TST.B instruction to check for the null byte at the end of the string,when it encounters the null byte the program ends.The result is in the D1 long word already! To do some error checking,you need to make some changes in the program.You'll do this right after you come back from the"nibblin" routine with the value of the current character. If the value in D0 is bigger than $F,there is an error.You can detect this in several ways.You chose the simplest one-you'll use CMP #$10,D0 to compare D0 with $10.If it smaller,then the C flag is set(since CMP uses subtraction)and everything is fine.If C is zero,there is an error. You can use this trick to skip the test for a null byte,since its an invalid character as well.The program looks like this: ;(4_3_3C) hex-conv2 optional disk name hexin: ;converting a hex number clr.l d1 ;first erase D1 move.l #string,a0 ;address of string in A0 jsr hexinloop ;test subroutine nop ;set breakpoint here hexinloop: bsr nibblein ;convert digit cmp $10,d0 ;test if good bcc hexinok ;no,then done lsl.l #4,d1 ;shift result or.b d0,d1 ;insert nibble bra hexinloop ;and continue hexinok: rts nibblein: ;convert the nibble from (A0) clr.l d0 ;erase D0 move.b (a0)+,d0 ;get digit,increment A0 sub #'A',d0 ;subtract $41 bcc ischar ;no problem:in the range A-F add #7,d0 ;else correct value ischar: add #10,d0 ;correct value rts string:DC.B "56789ABC',00 ;8 digit string ending with a ;null byte to be converted end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the NOP,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.Start the program and watch the contents of D1,the hex value is placed in this register. This is the method for converting hex to binary.If you convert decimal to binary,the conversion is not much harder. 4.3.4.Converting ASCII To Decimal. --------------------------------- You can use a very similar method to the one used above.Since you are not sure how many digits there are,you'll use a similar method for putting digits of a number in the next place up.You can't do this with shifting,but you can multiply by 10 and add the value of the digit. Heres the program for converting decimal numbers. decin: ;converting a decimal number clr.l d1 ;first erase D1 move.l #string,a0 ;the string to convert jsr decinloop ;test subroutine nop ;breakpoint here decinloop: bsr digitin ;convert digit cmp #10,d0 ;test,if valid bcc decinok ;no,then done mulu #10,d1 ;shift result add d0,d1 ;insert nibble bra decinloop ;and continue decinok: rts ;end of conversion digitin: ;converting the nibble from (A0) clr.l d0 ;erase D0 move.b (a0)+,d0 ;get digit,increment A0 sub #'0',d0 ;subtract $30 rts string:dc.b '123456' ;ASCII decimal string to convert end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the NOP,to set the breakpoint in AssemPro select the correct address with the mouse and press thr right-Amiga-B keys.Select "Parameter-Output-numbers-Decimal"so the registers are displayed as decimal numbers.Then start the program and watch the contents of D1,the decimal value is placed in this register. This program can ONLY convert numbers upto 655350,although the hex conversion routine can go higher.Thats because the MULU command can only multiply 16-bit words.The last multiplication that can be done correctly is $FFFF*10--65535*10,which gives us the value 655350.Normally this is a large enough range,so you won't complicate the program further. CHAPTER 5. --------- 5.Hardware Registers. -------------------- You can get information about hardware functions without using library functions.You can use the hardware registers instead.These are memory locations at particular addresses that are neither in RAM nor in ROM.They are direct interfaces between the processor and its peripheral devices. Each device has a number of hardware registers that the processor accesses to control graphics,sound and input/output.There are lots of possibilities for assembly language programmers.We'll only be able to go into a few examples. The registers are generally used in byte-wise fashion.You'll find an example in the next chapter. 5.1.Checking For Special Keys. ----------------------------- Load AssemPro and enter the debugger,select "Parameter-Display- From-Address"and enter $BFEC00.Next select "Parameter-Display-Hex -Dump"to display the memory.(To use the SEKA assembler or a similar monitor program,enter "q $bfec00".) Yoy'll see a byte-wise listing of the addresses starting at $BFEC00 in which two bytes always repeat.These two bytes represent the status of the two hardware registers. The mirroring occurs because not all the address bits are used in decoding the address.In addressing this register,only the upper two bytes of the address and the low bit,bit 0,are used.The address of the two registers goes like this:$BFECxx,where the lower address byte xx doesn't contain any information in bits 1-7. Only bit 0 contains information about the desired register.You'll find this odd form of addressing with most hardware registers. Let's look at the information in these registers.Let's look at the second register,$BFEC01.Hold down thekey and select"Parameter -Display-HEX-Dump"to redisplay the screen.(SEKA owners must enter "q $bfec00"and press thekey right after pressing the key.)You'll see that contents of every two bytes($BFEC01,$BFEC03, etc...)have been changed to $37.This is the status of the special keys.This is also true for the other special keys.The following keys produce the bytes: Shift left $3F Shift right $3D Control $39 Alternate $37 Amiga left $33 Amiga right $31 You can use this register to have a machine language program check if one of these keys was pressed and then respond by calling or ending a function.A program section might look like this: skeys=$bfec01 ... cmp.b #$37,skeys ;Alternate pressed? beq function1 ;Yes! cmp.b #$31,skeys ;or right Amiga? beq function2 ;Yes! ... ;and so on... 5.2.Timing. ---------- If you want to find out how much time elapsed between two events, you can use a hardware register to keep track of time quickly and precisely.The Amiga contains just such a timekeeper:the I/O port componant.The chip has a 24 bit wide counter that has a 60 Hertz clock. These 24 bits can't be read at once,for instance with a MOVE.L command,because the register is divided into three bytes.The low byte is at address $BFE801,the middle at $BFE901,and the high byte with bits 16-23 at $BFEA01. Here's an example of a way to use this register:finding out how long a subroutine takes to run. test: bsr gettime ;put current time in D7 move.l d7,d6 ;save it in D6 bsr routine ;routine to be timed bsr gettime ;get the time again sub.l d6,d7 ;elapsed time in ... ;1/50 seconds in D7! nop ;set break point here to stop routine: ;test routine move #500,d0 ;delay counter loop: dbra d0,loop ;count down rts gettime: move.b $bfea01,d7 ;hi-byte in D0 lsl.l #4,d7 ;shift twice by 4 bits lsl.l #4,d7 ;(8 bits shifted) move.b $bfe901,d7 ;get mid-byte lsl.l #4,d7 lsl.l #4,d7 ;shift again move.b $bfe801,d7 ;get the lo-byte rts ;done 5.3.Reading The Mouse-Joystick. ------------------------------- There are two hardware registers for the mouse and the joystick. They contain the state(or the position)of these input devices.Its interesting that the same port is used with both the mouse and the joystick even through they work completely different. The joystick as four switches that are closed during movement and give off a potential(-)that is related to the movement of the joystick/mouse.The mouses movements give off lots of quick signals -two for horizontal and two for vertical movements. The computor must keep an eye on the ports so that it can evaluate the signals and calculate the new mouse position.This isn't the work of the processor though;it already has too much to do. You find the status of the mouse/joystick port at address $DFF00A for port 1 and $DFF00C for port 2.The information in these words is for vertical mouse movement in the lower byte and for horizontal movement in the upper byte. AssemPro owners be careful!Don't read these addresses,because for some reason that causes the computor to crash.This looks interesting(the screen begins to dance)but you can only recover by pressing and losing all your data. To read this register,lets write a short program: ;(5.3A) mouse test: jsr run ;test subroutine jmp test ;continue until broken nop ;breakpoint here joy= $dff00a run: move joy,d6 ;data item 1 in D6 move joy+2,d7 ;data item 2 in D7 jmp run ;rts for SEKA and other end If you assemble the program and start breakable in the debugger (SEKA-"j run"),D6 and D7 contain the contents of the two registers Move the mouse a bit and watch the register contents. As you see,the value in D6 is different.If you just move the mouse horizontaly,only the upper bytes value is different,if just moved vertically only the upper byte is different. You are not getting the absolute position of the mouse pointer on the screen.You can see that easily by moving the mouse in the upper left corner,then reading the value by restarting the program and moving the mouse left again.As you can see,the registers contents are always relative. Change the program as follows: ;(5.3B) mouse difference test: jsr run ;test subroutine jmp test ;continue until broken nop ;breakpoint here joy= $dff00a run: move d7,d6 ;old position in D6 move joy,d7 ;new position in D7 sub d7,d6 ;difference in D6 jmp run ;rts for SEKA and other end Start Breakable(right-Amiga-A)in the AssemPro debugger and watch D6,the result is zero or D7.(SEKA owners have to start the program two times.The result in D6 is zero.)If you move the mouse,D6 contains the difference between the old and new positions since the start.You'll find the vertical and horizontal positions of the mouse relative to the last time you looked.In this way,you can use this register to find the relative mouse movement between two checks. Now to check the joysticks.Put a joystick in port 2 and change the address $DFF00A to $DFF00C in the program.Start Breakable in the AssemPro debugger and watch D6,the result is zero or D7.(SEKA owners have to start the program two times.The result in D6 is zero.) Move the joystick up.You'll get the value $FF00.One was subtracted from the upper byte.Let the joystick loose.This time you get the value $100-one is added.You'll get the same effect if you move the joystick left-after you let go,one is subtracted. The individual movements and their effects on the joystick program are: UP $FF00 HI-BYTE -1 DOWN $FFFF LO-BYTE -1 LEFT $0100 HI-BYTE +1 RIGHT $0001 LO-BYTE +1 These values aren't terribly reliable.If you move the joystick a lot and then look at the value,you'll find a crazy value in D6. This is because the input driver thinks that a mouse is attached. Nevertheless,this is the quickest way to read a joystick.In this way,an external device that gives off evaluatable TTL signals can be connected to the port and watched by a machine language program. Now you just need to find out whether the fire button has been pressed,and you'll know how to get all the information you need from the joystick.The buttons state is in bit 7 of the byte that is in memory location $BFE001.If the bit is set,the button was'nt pressed.That's true for the joystick connected to port 2.Bit 6 of this byte contains the buttons state when the joystick is in port 1 or the state of the left mouse button. Let's stay on port 2.You can test bit 7 to execute a function when the joystick button is pressed without any problems.Bit 7 is the sign bit.You can use this program segment: tst.b $bfe001 ;was fire button 2 hit? bpl fire ;yes!branch The TST.B instruction tests the addressed byte and sets the Z and the N flag.If the N flag is set,you know that bit 7 of the tested byte is set.Since the fire button turns on LO potential,the bit is erased when the button is pressed.The N flag works that way with the TST command as well.The BPL command in the program above branches if the button was pressed.The PL stands for plus and is set when the sign bit is cleared. Here is the complete program to check the fire button and joystick difference: ;(5.3C) fire button and joy difference test: jsr run ;test subroutine tst.b $bfe001 ;was fire button 2 hit? bpl fire ;yes! branch jmp test ;continue until broken joy = $dff00a run: move d7,d6 ;old position in D6 move joy,d7 ;new position in D7 sub d7,d6 ;difference in D6 jmp run ;rts for SEKA and other fire: nop ;breakpoint here end 5.4.Tone Production. ------------------- It's fun to make noises and sounds.The Amiga lets you use Audio Devices and various I\O structures to play tones,noises and/or music pieces in the background.You'll leave this method to C or Basic programmers,since you can use short machine language programs to directly program the audio hardware. The Paula chip has all the capabilities needed for tone production This chip can be accessed using the hardware registers of the processor.No library of any high level language can do more than you can-program the chip. How does it work?Since the disk uses Direct Memory Access(DMA)to get information,you just need to tell it where to look for the tone or tone sequences that you would like played.You also need to tell it how to interpret the data. Lets start with the easiest case-producing a constant tone.A tone like this consists of a single oscillation that is repeated over and over.If you make a diagram of the oscillation,you see the wave form of the oscillation.There are several standard waves: sine, square,triangle and saw tooth.The simplest is the square wave. To produce a square wave,you just need to turn the loud speaker on and off.The frequency that occurs here is the frequency of the tone. You want to produce such a tone using the Amiga.First you need to make a table that contains the amplitude of the tone you wish to produce.For a square wave,you only need two entries in the table,a large and a small value.Since the sound chip in the Amiga has amplitude values between -128 and +127,our table looks like this: soundtab: dc.b -100,100 You need to give the address of the table to the sound chip.You have four choices,since the Amiga as four sound channels.The address of the hardware register in which the table address for channel 0 must be written is $DFF0A0;for channel 1 it is $DFF0B0; for channel 2 its $DFF0C0;for channel 3 its $DFF0D0.For stereo output,channels 0 and 3 control the left loud speaker.Channels 1 and 2 control the right loud speaker.For example,choose channel 0 and write the following: move.l #soundtab,$DFF0A0 ;address of the table Next you need to tell the sound chip how many items there are in the table.The data is read from beginning to end and sent to the loud speaker.Once it reaches the end,it starts over at the beginning.Since the sound chip gets this one word at a time,even though the data is in bytes,the table must always have an even number of bytes.The length that you give it is the number of words the number of bytes/2. You put the length for channel 0 in the register at address $DFF0A4(for channel x just add x*$10!): move #1,$dff0a4 ;length of table in words Now you have to tell it how quickly to read the data and output it to the loud speaker.This word determines the frequency.However,it does this "backwards".The larger the value,the lower the frequency Choose the value 600 for this example: move #600,$dff0a6 ;read in rate Now you need to decide the loudness level for the tone or noise. You have 65 different levels to choose from.Lets choose the middle value 40 for our example: move #40,$dff0a8 ;loudness level Thats the data that the sound chip needs to produce the tone. However nothing happens yet.What next?The chip can't tell if the data thats in the registers is valid,so it doesn't know if it should use the data. You need to work with the DMA control register at address $DFF096 to let it know.You only need six bits of this word for your purposes: Bit 15 ($8000) If this bit is set,every bit that is written to this internal register is set.Otherwise the bits are erased.Zero bits aren't affected.This is very useful because this word also contains DMA information for disk operations that should'nt be changed. Bit 9 ($200) This bit makes it posible for the chip to access DMA memory.If you want to start playing the tone, you need to set this bit. Bit 0-3 Turn channel 0-3 on when bits are set. You'll start your tone by setting bits 15,9 and 0: move #$8000+$200+1,$dff096 ;start DMA Heres an example of tone production-this time with tone using a sine wave: ;**Sound Generation using hardware registers** (5.5A) ctlw = $dff096 ;DMA control cothi = $dff0a0 ;table address HI c0tlo = $c0thi+2 ;table address LO c0tl = $c0thi+4 ;table length c0per = $c0thi+6 ;read in rate c0vol = $c0thi+8 ;loudness level run: ;*Produce a simple tone move.l #table,c0thi ;table beginning move #8,c0tl ;table length--8 words move #400,c0per ;read in rate move #40,c0vol ;loudness level (volume) move #$8201,ctlw ;DMA/Start sound rts data ;>500K place in CHIP memory table: ;sound table:sine dc.b -40,-70,-40,0,40,70,40,0 end To test this subroutine,use AssemPro to assemble the routine,save the program and load it into the debugger.Next set a breakpoint at the RTS,to set the breakpoint in AssemPro select the correct address with the mouse and press the right-Amiga-B keys.Start the program and listen to the tone.You need another routine to turn the tone off,turn your sound down for now. To turn the tone off,you just need to erase bit 0 of the DMA control register.To do this,you just need to write a 0 in bit 15 and all the set bits in this register are erased.To erase bit 0, just write a one to the memory location:bit 15=0=> bit 0 is erased Heres a small routine to stop the tone coming from channel 0: still: ;*turn off tone move #1,ctlw ;turn off channel 1 rts Now lets use the routine in a program to produce a short peep tone that you culd,for instance,use as a key click: ;** Producing a Peep Tone ** ctlw = $dff096 ;DMA control c0thi = $dff0a0 ;HI table address c0tlo = $c0thi+2 ;LO table address c0tl = $c0thi+4 ;table length c0per = $c0thi+6 ;read in rate c0vol = $c0thi+8 ;volume beep: ;*Produce a short peep tone move.l #table,c0thi ;table beginning move #8,c0tl ;table length move #400,c0per ;read in rate move #65,c0vol ;volume move #$8201,ctlw ;Start DMA (sound) move.l #20000,d0 ;delay counter loop: dbra d0,loop ;count down still: move #1,ctlw ;turn off tone rts table: dc.b 40,70,90,100,90,70,40,0,-4,0 end You can play upto four tones at the same time in such a way that they are independant of each other.The Amiga also offers another method of making the sound more interesting:you can modulate the tone. Lets produce a siren tone.You could do this by figuring out the entire sequence and programming it.However,as you can well imagine thats a lot of work. Its much easier to use two tone channels.Lets use channel 1 for the bass tone and channel 0 for its modulation.Channel 0 needs to hold the envelope of the siren tone.It needs to give the expanding and contracting of the tone at the right speed. You then have two ways that you can have channel zero work with channel one.You can control the volume via channel 0,the read in rate(frequency),or both.For our example,you'll use frequency modulation. Change the program as follows: ;** Modulated sound generation via hardware registers ** ctlw = $dff096 ;DMA control adcon = $dff09e ;Audio/Disk control c0thi = $dff0a0 ;HI table address c0tlo = c0thi+2 ;LO table address c0tl = c0thi+4 ;table length c0per = c0thi+6 ;read in rate c0vol = c0thi+8 ;volume run: move.l #table,c0thi+16 ;table start for channel 1 move #8,c0tl+16 ;table length--8 words move #300,c0per+16 ;read in rate move #40,c0vol+16 ;volume move.l #table2,c0thi ;table start for channel 0 move #8,c0tl ;table length move #60000,c0per ;read in rate move #30,c0vol ;volume move #$8010,adcon ;modulation mode:FM move #$8203,ctlw ;start DMA rts still: ;*Turn Off Tone move #$10,adcon ;no more modulations move #3,ctlw ;turn off channels rts table: ;data for basic tone dc.b -40,-70,-90,-100,-90,-70,-40,0 dc.b 40,70,90,100,90,70,40,0 table2: ;data for modulation dc.w 400,430,470,500,530,500,470,430 end When you start the program,you'll here a siren.You can change this tone to your hearts content. Did you notice the added "adcon"register.This register controls the modulation of the audio channel as well as handling disk functions.The same technique is used here as for the DMA control register,bits can only be set if bit 15 is.As a result,you don't have to worry about the disk bits.I'd recommend against experimentation. Control bit 15 isn't the only one of interest to you.You can also use bits 0-7,because they determine which audio channel modulates another channel.There is a restriction,though.A channel can only modulate the next higher numbered channel.For this reason you use channel 1 for the basic tone and channel 0 for the modulation in the example.You can't for example,modulate channel three with channel zero.Channel 3 can't be used to modulate any other channel. Here is an overview of bits 0-7 of the "adcon"register. Bit Function ----------------------------------------------------------------- 0 Channel 0 modulates the volume of channel 1 1 Channel 1 modulates the volume of channel 2 2 Channel 2 modulates the volume of channel 3 3 Turn of channel 3 4 Channel 0 modulates the frequency of channel 1 5 Channel 1 modulates the frequency of channel 2 6 Channel 2 modulates the frequency of channel 3 7 Turn off channel 3 In the example,you set bit 4,which put channel 0 in charge of channel one's frequency modulations. When you've chosen a channel for use in modulating another channel some of the parameters of the channel change.You don't need to give volume for this channel,so you can omit it.Now the tables data is looked at as words instead of as bytes.These words are read into the register of the modulated register at a predetermined rate.The Read in Rate Register determines the rate. If you want to modulate the frequency and the volume of another channel,(In the example,set bits 0 and 4 of "adcon"),the data is interpreted a little differently.The first word in the table is the volume,the second is the read in rate,and so on.It alternates back and forth.In this way,you can for instance,produce the siren tone. 5.5.Hardware Registers Overview. ------------------------------- The following tables should give you an overview of the most important hardware registers.Theres not enough room to describe each register,so I'd recommend getting a hold of the appropriate literature.If you experiment with these registers,you should keep in mind that this can cause the computor to crash.Save your data to disk and then take the disk out of the drive,because you might cause the disk drive to execute some wierd functions. Lets start with the PIA's.This covers the PIA type 8520.You should keep in mind that some functions and connection of the 8520 are integrated into the Amiga and so there are limitations on what you can do with the PIA's. PIA A PIA B Registers Meaning ------------------------------------------------------------------ BFE001 BFE000 Data register A BFE101 BFE100 Data register B BFE201 BFE200 Data direction register A BFE301 BFE300 Data direction register B BFE401 BFE400 Timer A LO BFE501 BFE500 Timer A HI BFE601 BFE600 Timer B LO BFE701 BFE700 Timer B HI BFE801 BFE800 Event register Bits 0-7 BFE901 BFE900 Event register Bits 8-15 BFEA01 BFEA00 Event register Bits 16-23 BFEB01 BFEB00 Unused BFEC01 BFEC00 Serial data register BFED01 BFED00 Interrupt control register BFEE01 BFEE00 Control register A BFEF01 BFEF00 Control register B Some internal meanings: $BFE101 Data register for parallel interface $BFE301 Data direction register for the parallel interface $BFEC01 State of the keyboard,contains the last special key pressed(Shift,Alternate,Control,Amiga) Now come the registers that are used for tone production.The first two registers should be treated especially carefully-if they are used wrong,very nasty effects can occur. These registers can be either read or written only.This information is included under R/W in the table. Address R/W Meaning ------------------------------------------------------------------ DFF096 W Write DMA Control DFF002 R Read DMA Control and Blitter Status --Audio Channel 0-- DFF0AA W Data register DFF0A0 W Pointer to table beginning Bits 16-18 DFF0A2 W Pointer to table beginning Bits 0-15 DFF0A4 W Table length DFF0A6 W Read in Rate DFF0A8 W Volume --Audio Channel 1-- DFF0BA W Data register DFF0B0 W Pointer to table beginning Bits 16-18 DFF0B2 W Pointer to table beginning Bits 0-15 DFF0B4 W Table length DFF0B6 W Read in Rate DFF0B8 W Volume --Audio Channel 3-- DFF0CA W Data register DFF0C0 W Pointer to table beginning Bits 16-18 DFF0C2 W Pointer to table beginning Bits 0-15 DFF0C4 W Table length DFF0C6 W Read in Rate DFF0C8 W Volume --Audio Channel 4-- DFF0DA W Data register DFF0D0 W Pointer to table beginning Bits 16-18 DFF0D2 W Pointer to table beginning Bits 0-15 DFF0D4 W Table length DFF0D6 W Read in Rate DFF0D8 W Volume Now for the registers that contain information about the joystick, mouse or potentiometer.These addresses have been gone over in part previously. Address R/W Meaning ------------------------------------------------------------------ DFF00A R Joystick/Mouse Port 1 DFF00C R Joystick/Mouse Port 2 DFF012 R Potentiometer pair 1 Counter DFF014 R Potentiometer pair 2 Counter DFF018 R Potentiometer connection DFF034 W Potentiometer port direction Chapter 6 --------- 6.The Operating System. ----------------------- Now lets take a step forward in your ability to write assembly language programs.Its not enough to put a piece of text in memory someplace.You want to be able to put it on the screen.Do you know how to write a character on the screen?Do you know how to draw a window on the screen that can be modified by the mouse?Actually you don't have to have terribly precise knowledge about such topics. Fortunately,the Amigas operating system supplies routines that take care of common tasks like this.It can seem quite complicated due to the number of routines necessary.These routines are in libraries.We'll look at the libraries in some depth now. 6.1.Load Libraries. ------------------- Before you can use a library,it must be available.It has to be loaded into memory.Unfortunately,the whole library must be loaded, even if you only need one of the functions. First you need to decide what the program must be able to do,so you can see which libraries you'll need.For simple I/O text,you don't need a library that contains routines for moving graphics! There are a number of libraries onj a normal Workbench disk.Heres an overview of the names and the sort of functions they do: Exec.Library; This library is needed to load the other libraries.It is already in memory and doesn't need to be loaded.Its in charge of basic functions like reserving memory and working with I/O channels. Dos.Library; Contains all the functions for normal I/O operations,for instance screen or disk access. Intuition.Library; Used for working with screens,windows,menus,etc... Clist.Library; This contains routines for working with the Copper lists that are used for controlling the screen. Console.Library; Contains graphics routines for text output in console windows. Diskfont.Library; Used for working with the character fonts that are stored on the disk. Graphics.Library; This library contains functions to control the Blitter(or graphics )chip.Its used for basic graphics functions. Icon.Library; Used in the development and use of workbench symbols(icons). Layers.Library; Used for working with screen memory (layers). Mathffp.Library; Contains basic math floating point operations. Mathieeedoubbas.Library; Contains basic math functions for integers. Mathtrans.Library; Contains higher level mathmatical functions. Potgo.Library; Used for evaluating analog input to the Amiga. Timer.Library; Contains routines for time critical programs.They can be used to program exact time intervals. Translator.Library; Contains the single function "Translate",that translates normal text written phonetically for the narrator,the speech synthesisor. You can open(load)all these libraries of course.You should remember that this takes time and memory.For this reason,you should always think about which functions you need and which libraries they are in. For example,lets say you want to write a program that does text input/output.You need the "Dos.Library",so it can be loaded. The "exec.library"is in charge of loading.This library contains the OpenLib function that can be called once you've passed the needed parameters.AssemPro Amiga includes all the libraries necessary for the Amiga,it also includes files that contain the offsets for the operating system calls.The macros contained in AssemPro ease assembly language programming considerably.To make the programs in this book useful to the largest audience the following examples are written for generic assemblers and do not include AssemPro's macros.We have used the AssemPro ILABEL and the macros INIT_AMIGA and EXIT_AMIGA so AssemPro owners can start the programs from the desktop.(If you are using a different assembler check your documentation for instructions on linking programs). 6.2.Calling Functions. ---------------------- Since this chapter is rather complex we'll first describe the fundamental routines necessary to use the Amiga's operating system after a description a complete program is listed.Every library begins in memory with a number of JMP commands.These JMPs branch to the routines that are in the library.To call a function,you need to find the beginning of this JMP table and call function x by going to the xth JMP command.Usually you use an offset to get to the right JMP command.Normally,you don't start at the beginning but at the end of the JMP table,so use negative offsets. It works out very easily.Now lets open the "dos.library"by using "exec.library's"base address.This address is $000004.To call a fuction from another library,you need to use another base address. Now you need the offset for the function that you want.You want the OpenLib function that has -408 as an offset.You'll find a list of function offsets in the appendix. You need a pointer to the name of the library you are loading for the OpenLib function(in this case "dos.library")and a long word in memory that you can use to store the base address of the DOS library.You get this back from the OpenLib function.You need to be sure to write the library name in lower case letters(dos.library), otherwise you can't open it.I entered a name in capitol letters once and spent a lot of time finding this error. The routine looks like this: ;** Load the DOS library 'dos.library' (6.2A) ** Execbase = 4 ;base address of the EXEC library OpenLib = -408 ;offset for the OpenLib function IoErr = -132 ;offset for IoErr information init: move.l Execbase,a6 ;base address in A6 lea dosname,a1 ;address of library name moveq #0,d0 ;version number jsr OpenLib(a6) ;open DOS library move.l d0,dosbase ;save DOS base address beq error ;if zero,then error! ... ;your program goes here ... ;more program... error: ;error move.l dosbase,a6 ;address of library name jsr IoErr(a6) ;call IoErr for error info move.l d0,d5 ... ;your error routine goes here rts dosname: ;name of library to open dc.b 'dos.library',0,0 align ;SEKA uses-even dosbase: ;storage for DOS base address blk.l 1 end This is the way to load the DOS library so that you can use it.All library functions are called this way.Parameters are put in registers and passed to the function.When there is an error,when the function doesn't run correctly,a zero is usually put in data register D0. Once your program is done with its work,you need to close the libraries that are still open before you return to the CLI or Workbench.The CloseLib function (offset -414)takes care of this job.This function is in the EXEC library just like the OpenLib.The only parameter it needs is the base address of the library that is closed.To close "dos.library",do the following: CloseLib = -414 ; (6.2B) ... move.l Execbase,a6 ;EXEC base address move.l dosbase,a1 ;DOS base address jsr CloseLib(a6) ;close library 6.3.Program Initialization. --------------------------- Before you can start a program,you need to initialize many things so that the program can run. Lets take an example program that does some text editing.A program like this must be able to store text,so it needs to be able to access memory.It also needs to be able to accept keyboard input and do screen output,so it needs an output window. To do this,you need to open one or more of the libraries that we talked about earlier.Lets assume that you've loaded the DOS library,so that you can do the next steps. 6.3.1.Reserve Memory. --------------------- There are several ways to get the operating system to assign you a chunk of memory.You need to use one of them,so that during multi- tasking,you don't have one program overwriting another programs memory area. Lets look at the function that is normally used.This function is in the resident EXEC library and has the name AllocMem (offset -$c6).It reserves a memory area,using the value in D0 as the length.The address that the memory area begins at is returned in the D0 data register.If it returns zero,the program could'nt give you that much memory. You can also use a mode word in D1 to determine whether the memory area that is reserved should be erased or not. The routine looks like this: ExecBase = 4 ; (6.3.1A) AllocMem = -$c6 ... move.l #number,d0 ;number of bytes to reserve move #mode,a6 ;mode word move.l ExecBase,a6 ;DOS base address in A6 jsr AllocMem(a6) ;call function move.l d0,address ;save memory's start address beq error ;memory not reserved ... The second way to reserve memory is to use the AllocAbs function (offset -$CC).This function in contrast to the AllocMem function reserves a particular memory area.The D0 register contains the number of bytes that should be reserved.Address register A1 contains the desired start address.This function returns a zero in D0 if the memory area can't be reserved. ExecBase = 4 ; (6.3.1B) AllocAbs = -$cc ... move.l #number,d0 ;number of bytes to reserve lea address,a1 ;desired start address move.l execbase,a6 ;EXEC base address jsr AllocAbs(a6) ;reserve memory tst.l d0 ;everything ok? beq error ;no! ... When the program has done its work and must return to the CLI or the Workbench,it needs to return the memory it as reserved to the system.The FreeMem function (offset -$D2) handles this. The function works like AllocAbs in that the number of bytes is put in D0 and the start address of the memory area is put in A1. If you try to free up a memory area that was'nt reserved,you'll usually crash the computor. The routine to free up a memory area looks like this: ExexBase = 4 ; (6.3.1C) FreeMem = -$d2 ... move.l #number,d0 ;number of bytes released lea address,a1 ;start address from AllocAbs move.l ExecBase,a6 ;ExecBase address jsr FreeMem(a6) ;free up memory tst.l d0 ;everything ok? beq error ;no! ... 6.3.2.Opening a Simple Window. ------------------------------ The title of this chapter may sound a bit strange.However,the differences between the two different methods of opening a window are so great that they should be handled in seperate chapters. The method of opening a window presented here is very simple,but it doesn't allow you to work with all the gadgets.These gadgets include the close symbol in the upper left corner of a window and the size symbol in the lower left corner. If you open the window in the simple manner,almost all the gadgets are present.However,the close symbol is not.As a result,this method isn't appropriate for every application.Now lets look at the method. To open a window,use a function from the DOS library,so you need to open the library first (see the section "Load Library").This open function is an all purpose function that can be used for many things.For this reason,it makes good sense to put a "open" subroutine in your program.You can use it a lot.Lets do the basic steps: ;** Load the DOS Library 'dos.library' (6.3.2A) ** ExecBase = 4 ;base addres of the EXEC library OpenLib = -408 ;offset of OpenLib function Open = -30 ;Offset of the DOS function OPEN init: move.l ExecBase,a6 ;base address in A6 lea dosname(pc),a1 ;address of library name move.q #0,d0 ;version number:unimportant jsr OpenLib(a6) ;call the function move.l d0,dosbase ;save DOS base address beq error ;if zero,then error! ... ;more of your program ... ;now open window,etc... error: ... ;error occured ... ;your error routine openfile: ;general open function move.l dosbase,a6 ;DOS base address in A6 jsr Open(a6) ;call OPEN function tst.l d0 ;test if ok rts ;done,evaluate test later dosname: ;name of library to be opened dc.b 'dos.library',0,0 align ;even dosbase: ;spot for DOS base address blk.l 1 You call the Openfile routine,because the label "Open"is already being used for the offset.This routine calls the Open function that is in the DOS library. This isn't everything.The function must be given some parameters so that it knows what to open.The parameters are sent in registers D1 and D2.D1 points to a definition block what specifies what should be opened.You need to have a filename ended with a null byte there.D1 must be passed as a long word like all addresses.D2 contains the mode that the function should run in.There is an old (1005) and a new (1006) mode.This number must be passed in D2's long word. Heres an overview of how windows are opened.Fortunately,AmigaDos allows you to use input and output channels in the same way.The standard channels are disk files,the console (keyboard and screen) the printer interface and the serial RS232 interface. The console input/output is what you'll work with now.When you specify the console as the filename of the channel to be opened,a window is opened automatically. The name must begin with CON:to do this.Its similar to DF0:for disk operations.A little more infotmation about the window is still needed. You need to specify the X and Y coordinates of the upper left and lower right corners of the window as well as the name that should appear in the title line of the window.A complete definition block for a window like this would appear like the following line: consolname: dc.b 'CON:0/100/640/100/**Window**',0 To open this window,the line above needs to be inserted in the following program: mode_old = 1005 lea consolname(pc),a1 ;consol definition move.l #mode_old,d0 ;mode bsr openfile ;console open beq error ;didn't work move.l d0,conhandle rts ... conhandle: dc.l 1 ;space for handle There are two points to clear up yet. You should use mode_old as the the mode when you open a window. Logically the window doesn't exist before opening so this seems wierd but it doesn't hurt anything. The parameter that returns from "openfile"in D0 is zero in the case of an error,in the case that opening didn't work.Otherwise the value is the identification number (handle number) of the opened channel.You need to store it away,because every function that wants to use this channel must give the handle number.In the example,you stored this number in the "conhandle"long word. As mentioned,the window you've opened doesn't have a close symbol but it can be made bigger and smaller and moved forward and back. The manipulations that are carried out using the mouse are completely taken care of by the Amiga (in contrast to the ATARI ST where the programmer has to take care of these things). An important function that uses the handle number is the one that closes the channel (in your case the window).This function is also in the DOS library and is called "Close".Its offset is -36 and it only needs one parameter;the handle number of the channel that is closed must be in the D1 register. After your work is done,you need to put the following lines in your program to close the window: Close = -36 ; (6.3.2C) ... move.l conhandle,d1 ;handle number in D1 move.l dosbase,a6 ;DOS base address in A6 jsr Close(a6) ;close channel! The window disappears! Now for a few remarks about opening and closing the window in this way.If you open several windows in the same way,you'll get several windows and thus several handle numbers.In this way,you can put as many windows on the screen as you like.You can do your work with them and close them individually. Here is the complete program to open and close a simple window in AssemPro format (We have used the AssemPro ILABEL and the macros INIT_AMIGA and EXIT_AMIGA so AssemPro owners can start the program from desktop.If you are using a different assembler check your documentation for instructions on starting and exiting programs): ;***** 6.3.2 S.D ***** OpenLib =-30-378 closelib =-414 ;execbase =4 ;defined in AssemPro macros *calls to Amiga DOS: open =-30 close =-30-6 IoErr =-132 mode_old = 1005 alloc_abs =-$cc ILABEL AssemPro:includes/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bra test ;system-test init: ;system initialization and open move.l execbase,a6 ;number of execute-library lea dosname(pc),a1 moveq #0,d0 jsr openlib(a6) ;open DOS-Library move.l d0,dosbase beq error lea consolname(pc),a1 ;consol definition move.l #mode_old,d0 bsr openfile ;consol open beq error move.l d0,conhandle rts test: bra qu ;quit and exit error: move.l dosbase,a6 jsr IoErr(a6) move.l d0,d5 move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr closelib(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-Definition-Text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts dosname: dc.b 'dos.library',0,0 Align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/**CLI-Test**',0 Align.w conhandle: dc.l 0 end There is another way to open a window easily.Just use RAW:instead of CON:as the channel designator.All the other parameters and operations remain the same. If you try them both out,you won't see any differences between the two windows.They both look the same and can be worked with in the same way with the mouse.The difference comes when you input to the window.In the RAW:window,the cursor keys are ignored.In the CON: window and in CLI,they do work. 6.4.Input/Output. ----------------- Besides managing and making calculations with data,the most important work of a program is to input and output the data.There are many methods of data transfer in and out of the computor,for instance screen or printer output,keyboard input,using the serial or the parallel interface,tone or speech output and finally disk operations. You want to learn about all these methods of data input and output for programming and applications.We've written some programs as subroutines that should be useful for later programs.It makes good sense to make a library of these subroutines that can either be directly integrated in a new program or linked to a program.At the end of the sections there is a list of a complete program so you can see how the subroutines are used. To prepare for input/output,you need to have data to output and space to input data.To get this ready,you need a correct program beginning in which the EXEC and DOS libraries are opened and memory is reserved.After this,you begin most programs by outputing some text.The text can be a program title or the instruction to input data over the keyboard.Lets start looking at screen output. 6.4.1.Screen Output. -------------------- For a computor like the Amiga the first question is where should the screen output be sent?The answer is simple for many computors; they only have one screen,and output goes there.You need to specify which window to write to when you use the Amiga,however. There are two possibilites: 1.Output to CLI 2.Output to another window The first posibillity only exists if the program that makes the output was started from CLI.If not,you need to open your own custom window for your program.If so,you can use the window that was opened by the CLI for output. If you use the second method,you need to open a window.As you've already seen,there are three methods.For simple text and character output,the difference between the three sorts of windows isn't very great.Here you have a free hand in determining which sort of window to use.Lets open a CON:window and put its handle number in "conhandle". You've opened your window and want to output a title.You choose text to output and then put it in memory using a code segment like this: title: dc.b "** Welcome to this Program! **" titleend: align ;even The "align"(even) is a pseudo-op that should follow text when it is followed by either word data or program lines.It causes the assembler to insert a null byte if necessary to make the address even. To output this text you need another DOS function:Write.This has an offset of -48 and needs three parameters: In D1 the handle of an opened output channel that should be written to (in your case,this is the handle number that you go back from the Open command when you opened your window.). In D2 the address of the text to be output (in the example,the address "title"). In D3 the number of characters to be output in bytes. To find the number of bytes to output,you need to count the number of characters in your text.Use "titleend"to calculate this.Using this label,the assembler can calculate the length of your text for itself (after all,why should you count when you have a computor?) if you write: move.l #titleend-title,d3 The advantage of specifying the length is that you can put control characters between the beginning and end of the text.In this way, you can execute certain functions using text output.You'll learn about the control characters in a bit. Heres the routine: Write = -48 ; (6.4.1A) ... ;open window ... move.l dosbase,a6 ;DOS base address move.l conhandle,d1 ;pass handle move.l #title,d2 ;text address move.l #titleend-title,d3 ;and length jsr Write(a6) ;call function ... title: dc.b "** Welcome to this Program! **" titleend: align ;event end You'll certainly use this function a lot.You'll often want to output just one character though.To allow you to do this and similar text related tasks,there are four subroutines,each of which do a different sort of output: Pmsg; Outputs the text from (D2) to the first null byte. Pline; Is the same as the routine above except that the text is automatically followed by a CR,the cursor is positioned at the beginning of the next line. Pchar; Outputs the character in D0 Pcrlf; Puts the cursor at the beginning of the next line. Heres the subroutine package: Write = -48 ; (6.4.1B) ... pline: ;*output line and then a CR bsr pmsg ;output line pcrlf: move #10,d0 ;line feed bsr pchar ;output move #13,d0 ;and CR pchar: move.b d0,outline ;character in output buffer move.l #outline,d2 ;address of the character pmsg: ;*output line (D2) upto null move.l d2,a0 ;address in A0 clr d3 ;length = 0 ploop: tst.b (a0)+ ;null byte ? beq pmsg2 ;yes:length found addq.l #1,d3 ;else length + 1 bra ploop ;and continue looking pmsg2: move.l dosbase,a6 ;DOS base address in A6 move.l conhandle,d1 ;our window handle jsr Write(a6) ;call write function rts ;done! outline: dc.w 0 ;output buffer for 'pchar' conhandle: dc.l 0 ;windows handle Here is an example program to open and close a simple window and output a text message in AssemPro format (We have used the AssemPro macros INIT_AMIGA and EXIT_AMIGA so AssemPro owners can start the program from desktop.If you are using a different assembler check your documentation for instructions on starting and exiting programs.): Here is the complete program in AssemPro format: ;***** 6.4.1C.asm S.D. ***** Openlib =-30-378 closelib =-414 ;execbase = 4 ;Defined in AssemPro ;Macros * calls to Amiga Dos: open =-30 close =-30-6 write =-48 IoErr =-132 mode_old = 1005 alloc_abs =-$cc ILABEL AssemPro:include/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bsr test ;system test nop bra qu ;quit and exit test: move.l #title,d0 bsr pmsg bsr pcrlf bsr pcrlf rts init: ;system initialization and ;open move.l execbase,a6 ;number of execute-library lea dosname(pc),a1 moveq #0,d0 jsr openlib(a6) ;open DOS-library move.l d0,dosname beq error lea consolname(pc),a1 ;console definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts pmsg: ;print message (D0) movem.l d0-d7/a0-a6,-(sp) move.l d0,a0 move.l a0,d2 clr.l d3 ploop: tst.b (a0)+ beq pmsg2 addq.l #1,d3 bra ploop ;length calculate pmsg2: move.l conhandle,d1 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 rts pcrlf: move #10,d0 bsr pchar move #13,d0 pchar: ;output char in D0 movem.l d0-d7/a0-a6,-(sp) ;save all move.l conhandle,d1 pch1: lea outline,a1 move.b d0,(a1) move.l a1,d2 move.l #1,d3 ;1 letter move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 ;restore all error: move.l dosbase,a6 jsr IoErr(a6) move.l d0,d5 move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr closelib(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-definition- ;text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts dosname: dc.b 'dos.library',0,0 align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/** CLI-Test **',0 align.w conhandle: dc.l 0 title: dc.b '** Welcome to this Program! **' titleend: align outline: dc.w 0 ;output buffer for char end Using this program,you can very easily put whatever you want in the CON:window.These functions also work in RAW:window.You should rename "conhandle"as "rawhandle",so that you don't get things mixed up later. Lets stay with the CON:window.As mentioned earlier,you can output special characters that execute functions or change parameters for output.These characters are called control characters. You've already learned about one of these control characters,Line Feed ($A).This character isn't just output;instead,it calls a function that moves the cursor into the next line and moves the screen up.This is very useful,but there are much more interesting control characters. Here's a list of control characters that execute functions.These characters are given in hex. Control Sequence; Sequence Function ------------------------------------------------------------------ 08 Backspace 0A Line Feed,Cursor down 0B Move Cursor up a line 0C Clear screen 0D Carrige return,cursor in the first column 0E Turn on normal characters (Cancel Of Effects) 0F Turn on special characters 1B Escape The following sequences begin with $9B,the CSI (Control Sequence Introducer).The characters that follow execute a function.The values in square brackets can be left off.The n's you see represent one or more digit decimal numbers given using ASCII characters.The value that is used when n is left off,is given in the parenthesis that follow n in the description of the function in the table. Control Sequence Introducer; Sequence Function ------------------------------------------------------------------ 9B[n]40 Insert n blanks 9B[n]41 Move cursor n (1) lines up 9B[n]42 Move cursor n (1) lines down 9B[n]43 Move cursor n (1) characters to the right 9B[n]44 Move cursor n (1) characters to the left 9B[n]45 Move cursor down n (1) lines into column 1 9B[n]46 Move cursor up n (1) lines and into column 1 9B[n][3B n]48 Cursor in line;Set column 9B 4A Erase screen from cursor 9B 4B Erase line from the cursor 9B 4C Insert line 9B 4D Delete line 9B[n]50 Delete n characters starting at cursor 9B[n]53 Move up n lines 9B[n]54 Move down n lines 9B 32 30 68 Line feed => Line feed + return 9B 32 30 6C Line feed => just Line feed 9B 6E Sends the cursor position!A string of the following form is returned: 9B (line) 3B (column) 52 9B(style);(foreground colour);(Background Colour)6D The three parameters are decimal numbers in ASCII format.They mean: Style: 0 = normal 1 = bold 3 = italic 4 = underline 7 = inverse Foreground colour: 30-37 Colour 0-7 for Text Background colour: 40-47 Colour 0-7 for background 9B(length)74 sets the maximum number of lines to be displayed 9B(width)75 sets the maximum line length 9B(distance)78 defines the distance in pixels from the left border of the window to the place where output should begin 9B(distance)79 defines the distance in pixels from the upper border of the window to the place where output should begin The last four functions yield the normal values if you leave off the parameters. 9B 30 20 70 Make cursor invisible 9B 20 70 Make cursor visible 9B 71 Sends window construction.A string of the following form is returned: 9B 31 3B 31 3B (lines) 3B (columns) 73 To see how the control characters work,have "pmsg"output this text to your window: mytext: dc.b $9b,"4;31;40m" ; (6.3.2D) dc.b "underline" dc.b $9b,"3;33;40m",$9b,"5;20H" dc.b "** Hello World! **",0 The parameters for the control sequence are put in quotation marks so they are treated as an ASCII string.Now you see,just how easy it is to do text output! Here is the complete program to open and output the text and control codes to your window in AssemPro format (We have used the AssemPro macros INIT_AMIGA and EXIT_AMIGA so AssemPro owners can start the programs from desktop.If you are using a different assembler check your documentation for instructions on starting and exiting programs): ; ***** 6.4.1D.ASM S.D. ***** openlib =-30-378 closelib =-414 ;execbase = 4 ;defined in AssemPro macros * calls to Amiga Dos: open =-30 close =-30-6 write =-48 IoErr =-132 mode_old = 1005 alloc_abs =-$cc ILABEL AssemPro:includes/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bsr test ;system test nop bra qu ;quit and exit test: move.l #mytext,d0 bsr pmsg bsr pcrlf bsr pcrlf rts init: ;system initialization and open move.l execbase,a6 ;number of execute-library lea dosname(pc),a1 moveq #0,d0 jsr openlib(a6) ;open DOS-Library move.l d0,dosbase beq error lea consolname(pc),a1 ;console definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts pmsg: ;print message (D0) movem.l d0-d7/a0-a6,-(sp) move.l d0,a0 move.l a0,d2 clr.l d3 ploop: tst.b (a0)+ beq pmsg2 addq.l #1,d3 bra ploop pmsg2: move.l conhandle,d1 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 rts pcrlf: move #10,d0 bsr pchar move #13,d0 pchar: ;output char in D0 movem.l d0-d7/a0-a6,-(sp) ;save all move.l conhandle,d1 pch1: lea outline,a1 move.b d0,(a1) move.l a1,d2 move.l #1,d3 ;one letter move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 ;restore all rts error: move.l dosbase,a6 jsr IoErr(a6) move.l d0,d5 move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr closelib(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-definition- ;text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts dosname: dc.b 'dos.library',0,0 align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/ ** CLI-Test **',0 align.w conhandle: dc.l 0 mytext: dc.b $9b,'4;31;40m' dc.b 'underline' dc.b $9b,'3;33;40m',$9b,'5;20H' dc.b '** Hello World !! **',0 align outline: dc.w 0 ;output buffer for pchar end Now that you've done text and character output,its time to move on to text input. 6.4.2.Keyboard Input. --------------------- You can read keyboard input very easily.You just need to open the I/O channel of the CON:window and read from it.You need the read function from the DOS library to do this.Its offset is -42. The function has three parameters just like the WRITE function. In D1 the handle number that you get from the WRITE function. In D2 the address that the data read in is to start. In D3 the number of bytes to read. Here is a subroutine that reads the number of characters from the keyboard that it finds in D3.It puts them in a buffer. read = -42 ; (6.4.2A) ... getchr: ;* Get (D3) characters from the ;keyboard move.l #inbuff,d2 ;address of buffer in D2 move.l dosbase,a6 ;DOS base address in A6 move.l conhandle,d1 ;our window handle jsr read(a6) ;call read function rts ;done! inbuff: blk.b 80,0 ;buffer for keyboard input This routine returns to the main program when is entered. If more than D3 characters are entered,"inbuff"only gets the first characters.The routine gets the remaining characters when called a second time. This sort of input is fairly easy.You can backspace,because only the characters that should be there are put in the memory block starting at "inbuff".The number of characters moved into "inbuff" is put in D0. Try the program out as follows: After opening the CON:window,put the following lines in the main program: move #80,d3 ;read 80 characters (6.4.2B) bsr readchr ;get line from keyboard lea inline,a0 ;address of line in A0 clr.b 0(a0,d0) ;null byte on the end bsr pmsg ;output line again bp: After this comes the code segment that closes the window again. After loading the program into the AssemPro debugger,make "bp"a breakpoint and start the program.(SEKA users start the program with "g run"and enter "bp"as the breakpoint).The program quits at the breakpoint and you can take a look at the results on the screen.Then you can continue the program (SEKA with "j bp") and let the window close. After starting the program and opening the window,the cursor appears in the upper left corner of the window.Enter some text and press .The string that you just entered is output again on the screen. You use the "pmsg"routine from the previous chapter to do this output.This routine needs a null byte at the end of the text to be output.You put a null byte there by putting the address of the input buffer in A0 and then erasing the byte at A0+D0 using the CLR.B command.Since D0 contains the number of characters that were entered,this byte is the first unused byte. Since you're in the debugger you can redisplay the disassembled output when the program ends to see what "getchr"put in "inbuff" (SEKA owners can use "q inbuff"when the program ends to see what "getchr"put there.)You'll find the characters that you typed plus a closing $A.The $A stands for the key and its counted too,so if you entered a 12 and then hit ,for example,D0 will contain a 3. Try this again with a RAW:window.Change the window definition from CON: to RAW:and reassemble the program.You'll notice the diference right away.After you've entered one character,a return is executed D0 always as one bit in it. The advantage of this form of input is that cursor and function keys can be recognized.Using your own routine,you can repeatedly accept input of characters using "getchr"and then work with the special characters. Theres another form of keyboard input:checking for a single key. This is important when a program is about to execute an important function and the user must say he wants it executed by entering "Y"for yes.This can be treated as normal input,but in some cases, there is a better method. There is a function in the DOS library that waits a certain specified length of time for a key to be pressed,and returns a zero (FALSE) if no key was hit in this time period.It returns a -1 ($FFFFFFFF = TRUE) if one was.To find out which key it takes another function.The WaitForChar function,is only good for tasks like waiting for the user to let the program know that it can continue scrolling text. The function needs two parameters: In D1 the handle number of the window or file from which the character should be read.It can also wait for a character from an interface. In D2 you pass the length of time in microseconds that you should wait for a key stroke. To wait one second for one key to be hit,you can use the following routine: WaitForCh=-30-174 ; (6.4.2C) ... scankey: ;* Wait for a key stroke move.l conhandle,d1 ;in our window move.l #1000000,d2 ;waiting time 1 second move.l dosbase,a6 ;DOS base address jsr waitforch(a6) ;wait... tst.l d0 ;test result rts The TST command at the end of the program allows the calling routine to use a BEQ or BNE command to evaluate the results of the routine-BEQ branches if no key was hit.BNE doesn't. Heres an example program in AssemPro format covering what you have learned so far.Opening and closing a window,displaying text in the window and inputting text: ;***** 6.4.2A.ASM S.D ***** openlib =-30-378 closelib =-414 ;execbase =4 ;defined in AssemPro ;Macros * call to Amiga.Dos: open =-30 close =-30-6 read =-42 write =-48 IoErr =-132 mode_old =1005 alloc_abs =-$cc ILABEL AssemPro:include/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bsr test ;system test nop bra qu ;quit and exit test: move.l #mytext,d0 bsr pmsg bsr pcrlf bsr pcrlf move.l #80,d3 ;80 characters to read in (D3) bsr getchr ;get character bsr pmsg ;output line rts init: ;system initialization and open move.l execbase,a6 ;number of execute-library lea dosname(pc),a1 moveq #0,d0 jsr openlib ;open DOS-Library move.l d0,dosbase beq error lea consolname(pc),a1 ;console definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts pmsg: ;print message (D0) movem.l d0-d7/a0-a6,-(sp) move.l d0,a0 move.l a0,d2 clr.l d3 ploop: tst.b (a0)+ beq pmsg2 addq.l #1,d3 bra ploop ;check length pmsg2: move.l conhandle,d1 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 rts pcrlf: move #10,d0 bsr pchar move #13,d0 pchar: ;character in D0 output movem.l d0-d7/a0-a6,-(sp) ;save all move.l conhandle,d1 pch1: lea outline,a1 move.b d0,(a1) move.l a1,d2 move.l #1,d3 ;1 letter move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 ;restore all rts getchr: ;get character for keyboard move.l #1,d3 ;1 character move.l conhandle,d1 lea inbuff,a1 ;buffer address move.l a1,d2 move.l dosbase,a6 jsr read(a6) clr.l d0 move.b inbuff,d0 rts error: move.l dosbase,a6 jsr IoErr(a6) move.l d0,d5 move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr ;close lib (A6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-Definition- ;Text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts dosname: dc.b 'dos.library',0,0 align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/** CLI-TEST **',0 align.w conhandle: dc.l 0 mytext: dc.b '** Hello World !! **',0 align outline: dc.w 0 ;output buffer for pchar inbuff: blk.b 8 ;input buffer end 6.4.3.Printer Control. ---------------------- Now that you've looked at console I/O,lets look at outputting data from the computor.The first device that we'll discuss is the printer. Its very easy to use the printer.You just need to open another channel.It goes just the way you learned it with CON: and RAW: windows;the only difference is you enter PRT:instead. You open this channel using the same lines that you used above for the window except that the pointer is to the channel name PRT:in D1.You pass the mode "new"(1006) in D2 in the "do_open"routine as well.Save the handle number that comes back at a label called "prthandle". Now you can use the same output routines that you used with the windows to send text to the printer.You need to put "prthandle" instead of "conhandle"in the line with the "move.l conhandle,d1" command. Actually it would be better to eliminate this line from the routine totally.Then you can use the same routine for window and printer output.The calling procedure would then need to put "conhandle"in D1 for window output.It would put "prthandle" in D1 for printer output.This is a very flexible output routine that can be used for window and printer output now.You can't accept input from the printer,because the printer doesn't send data.It just accepts it and prints it. 6.4.4.Serial I/O. ----------------- Its just as easy to use the serial interface as the printer.Just enter SER:as the filename.Now you can use the DOS functions READ and WRITE just as before to do I/O channels you've just opened. You can set the parameters for the interface (like Hand shake and Transfer rate) with the Preferences program. 6.4.5.Speech Output. -------------------- The Amiga has a speech synthesizer built in.This isn't quite as easy to program as the I/O devices discussed earlier,however.You use the "narrator.device"to do this. This device requires several program steps to install it and then causes it to speak.You need to open the device,start the I/O,etc.. Lets look at how to translate the text into the proper form and then output the text. First we need to do some initialization.Lets define the constants now.Some of them are new. ;***** Narrator Basic Functions 3/87 S.D ***** (6.4.5A) openlib =-408 closelib =-414 execbase = 4 open =-30 ;open file close =-36 ;close file mode_old = 1005 ;old mode opendevice =-444 ;open device closedev =-450 ;close device sendIo =-462 ;start I/O abortIO =-480 ;abort I/O translate =-30 ;translate text ;The initialization routine follows: init: ;initialize and open system ;* open DOS library * move.l execbase,a6 ;pointer to execbase lea dosname,a1 ;pointer to DOS name moveq #0,d0 ;version unimportant jsr openlib(a6) ;open DOS library move.l d0,dosbase ;save handle beq error ;error handle ;* Open translator.library * lea transname,a1 ;pointer to translator name clr.l d0 jsr openlib(a6) ;open translator move.l d0,transbase ;save handle beq error ;error handling ;* Set up I/O area for Narrator * lea talkio,a1 ;pointer to I/O area in A1 move.l #nwrrep,14(a1) ;enter port address move.l #amaps,48+8(a1) ;pointer to audio mask move #4,48+12(a1) ;number of the mask move.l #512,36(a1) ;length of the output area move #3,28(a1) ;command:write move.l #outtext,40(a1) ;address of output area ;* Open Narrator device * clr.l d0 ;number 0 clr.l d1 ;no flags lea nardevice,a0 ;pointer to device name jsr opendevice(a6) ;open narrator.device tst.l d0 :error? bne error ;Yes! ;* Open Window * move.l #consolname,d1 ;console definition move.l #mode_old,d2 ;old mode move.l dosbase,a6 ;DOS base address jsr open(a6) ;open window tst.l d0 ;error? beq error ;Yes! move.l d0,conhandle ;else save handle After you've done this initialization,you can have the computor save the text you have prepared for it.To see what the Amiga is saying,use the "pmsg"function to have the text written to the window: move.l #intext,d2 ;text for the Amiga to say bsr pmsg ;output in window also sayit: ;have the text said ;*Translate the text into a form that the computor can use * lea intext,a0 ;address of the text move.l #outtext-intext,d0 ;length of the text lea outtext,a1 ;address of output area move.l #512,d1 ;length of output area move.l tranbase,a6 ;translator base address jsr translate(a6) ;translate text ;* Speech output * lea talkio,a1 ;address of I/O structure move.l #512,36(a1) ;length of output area move.l execbase,a6 ;EXEC base address jsr sendIO(a6) ;start I/O (speech output) Once the program ends,the I/O stops as well,so you need to put in something that keeps the program going longer.You'll use the "getchr"function that you programmed earlier to take care of this: bsr getchr ;wait for keyboard input The computor waits until the key is pressed.Now you can listen to what the Amiga as to say.Once the key is pressed,the program stops. qu: ; (6.4.5C) move.l execbase,a6 ;EXEC base address lea talkio,a1 ;pointer to I/O area jsr abortio(a6) ;stop the I/O move.l conhandle,d1 move.l dosbase,a6 jsr close(a6) ;close window move.l dosbase,d1 move.l execbase,a6 jsr closelib(a6) ;close DOS library lea talkio,a1 jsr closedev(a6) ;close narrator.device move.l tranbase,a1 jsr closelib(a6) ;close translator library rts ;* end of program Now comes the data that you need for the program above: mytext: dc.b 'This is a test text !',10,13,10,13,0,0 dosmame: dc.b 'dos.library',0,0 transname: dc.b "translator.library",0 consolname: dc.b 'RAW:0/100/640/100/** Test window',0 nardevice dc.b 'narrator.device',0 align dosbase: dc.l 0 tranbase dc.l 0 amaps: dc.b 3,5,10,12 align conhandle: dc.l 0 talkio: blk.l 20,0 nwrrep: blk.l 8,0 intext: dc.b 'hello,i am the amiga talking to you',0 align outtext: blk.b 512,0 This is quite a bit of work,but its worth it because it opens so many possibilities for you.There are a lot of variations possible if you modify parameters.These parameters are entries in the I/O area starting at the "talkio"label.The area is built as follows: Offset Length Meaning ---------------------------------------------------------------- ** Port Data ** 0 L Pointer to next block 4 L Pointer to last block 8 B I/O type 9 B Priority 10 L Pointer to I/O name 14 L Pointer to port 18 W Length ** I/O Data ** 20 L Pointer to device 24 L Pointer to device unit 28 W Command word 30 B I/O flags 31 B I/O status 32 L I/O pointer 36 L I/O length 40 L Pointer to Data 44 L I/O offset ** Narrator data items ** 48 W Speech speed 50 W Highness of voice 52 W Speech mode 54 W Sex (male/female voice) 56 L Pointer to audio mask 60 W Number of mask 62 W Volume 64 W Read in rate 66 B Flag for producing graphics (0=off) 67 B Actual mask (internal use) 68 B Channel used (internal use) We would'nt recommend experimenting with the data in the first two blocks.If you do,you can easily cause a system crash.You can use the last entries of the structure to produce some interesting effects though. Heres an overview of the parameters you can use to vary the speech output.The value in parenthesis is the standard value,the value set when narrator.device is opened. Speech speed (150); You can use this to set the speed of speech.The pitch of the voice is not affected by this value. Pitch of voice (110); You can choose a value between 65 and 320 for the pitch (from Goofy to Mickey Mouse). Speech mode (0); The zero gives half-way naturel speech.A one lets the Amiga speak in monotone like a robot. Sex (0); A zero means masculine and a one means feminine (more or less..) Volume (64); The volume can range from 0 to 64.The standard value is the loudest possible. Read in rate (22200); By lowering this value,the voice is lowered.If you change this very much,you'll get some wierd voices! You can experiment a bit until you find a interesting voice.Have fun! Here is a complete talking program in AssemPro format: ;***** Speech output S.D. ***** openlib =-30-378 closelib =-414 ;execbase =4 ;defined by AssemPro * calls to Amiga Dos: open =-30 close =-30-6 opendevice =-444 closedev =-450 addport =-354 remport =-360 ;DoIo =-456 sendIo =-462 abortIo =-480 read =-30-12 write =-30-18 ;myinput =-30-24 ;output =-30-30 ;currdir =-30-96 ;exit =-30-114 waitforch =-30-174 findtask =-294 translate =-30 mode_old = 1005 ;mode_new = 1006 ;alloc_abs =-$cc ;free_mem =-$d2 ;!!!when>500KB !!! or place in chip memory ;org $40000 ;load $40000 ;!!!!!!!!!!!!!!!!!!!!!!! ILABEL AssemPro:includes/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bra test ;system-test init: ;system initialization and ;open move.l execbase,a6 ;pointer to exec library lea dosname(pc),a1 ;pointer to dos name moveq #0,d0 ;version:not important jsr openlib(a6) ;open DOS-Library move.l d0,dosbase ;save handle beq error ;error routine ;* ;open translator library move.l execbase,a6 ;pointer to exec library lea transname,a1 ;pointer to translator library clr.l d0 jsr openlib(a6) ;open translator move.l d0,tranbase ;save handle beq error ;error routine ;* ;set up sub.l a1,a1 move.l execbase,a6 jsr findtask(a6) ;find task move.l d0,nwrrep+2 lea nwrrep,a1 jsr addport(a6) ;add port ;* ;open narrator device lea talkio,a1 ;pointer to I/O area in A1 move.l #nwrrep,14(a1) ;enter port address clr.l d0 ;number 0 clr.l d1 ;no flags lea nardevice,a0 ;pointer to device name jsr opendevice(a6) ;open narrator.device tst.l d0 ;error? bne error ;Yes! ;* ;set up I/O for narrator ;device bp: lea talkio,a1 ;pointer to I/O in A1 move.l #nwrrep,14(a1) ;enter port address move.l #amaps,48+8(a1) ;pointer to audio mask move #4,48+12(a1) ;size of mask lea consolname(pc),a1 ;console-definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts test: move.l #mytext,d0 bsr pmsg ;test-text output bsr sayit ;say text bsr readin ;input move #10,d0 bsr pchar ;LF output move.l #inline+2,d0 bsr pmsg ;and again bsr pcrlf bra qu error: move.l #-1,d7 ;flag qu: move.l execbase,a6 lea talkio,a1 jsr abortio(a6) move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr closelib(a6) lea nwrrep,a1 jsr remport(a6) ;remove port lea talkio,a1 jsr closedev(a6) ;close narrator device move.l tranbase,a1 jsr closelib(a6) ;close translator library EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O definition- ;text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts pmsg: ;print message (D0) movem.l d0-d7/a0-a6,-(sp) move.l d0,a0 move.l a0,d2 clr.l d3 mess1: tst.b (a0)+ beq mess2 addq.l #1,d3 bra mess1 ;length calculate mess2: move.l conhandle,d1 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 rts pcrlf: move #10,d0 bsr pchar move #13,d0 pchar: ;output characters in D0 movem.l d0-d7/a0-a6,-(sp) ;save all move.l conhandle,d1 pch1: lea chbuff,a1 move.b d0,(a1) move.l a1,d2 move.l #1,d3 ;1 letter move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 ;restore all rts scankey: ;test key move.l conhandle,d1 move.l #500,d2 ;wait value move.l dosbase,a6 jsr waitforch(a6) tst.l d0 rts readin: ;input from keyboard movem.l d0-d7/a0-a6,-(sp) ;save registers lea inline+2,a2 ;pointer to input buffer clr.l (a2) inplop: bsr getchr cmp.b #8,d0 beq backspace cmp.b #127,d0 ;delete? beq backspace bsr pchar ;character output cmp.b #13,d0 beq inputx move.b d0,(a2)+ bra inplop inputx: clr.b (a2)+ sub.l #inline,a2 move a2,inline ;length in lines+1 movem.l (sp)+,d0-d7/a0-a6 ;registers rts backspace: cmp.l #inline,a2 ;at the beginning? beq inplop ;yes move.b #8,d0 bsr pchar ;backspace move #32,d0 bsr pchar ;blank move #8,d0 bsr pchar ;backspace clr.b (a2) subq.l #1,a2 bra inplop getchr: ;get one character from ;keyboard move.l #1,d3 ;one character move.l conhandle,d1 lea inbuff,a1 ;buffer address move.l a1,d2 move.l dosbase,a6 jsr read(a6) clr.l d0 move.b inbuff,d0 rts sayit: lea intext,a0 move.l #outtext-intext,d0 lea outtext,a1 move.l #512,d1 move.l tranbase,a6 jsr translate(a6) p: lea talkio,a1 move #3,28(a1) ;?? move.l #512,36(a1) move.l #outtext,40(a1) move.l execbase,a6 jsr sendio(a6) rts mytext: dc.b 'This is our Test-Text !',10,13,10,13,0,0 dosname: dc.b 'dos.library',0,0 transname: dc.b "translator.library",0 align.w dosbase: dc.l 0 tranbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/* Speech-Test S.D.* ',0 nardevice: dc.b 'narrator.device',0 amaps: dc.b 3,5,10,12,0,0 align.w conhandle: dc.l 0 inbuff: blk.b 8 inline: blk.b 180,0 chbuff: blk.b 82,0 narread: blk.l 20,0 talkio: blk.l 20,0 nwrrep: blk.l 8,0 intext: dc.b 'hello,i am the amiga computor',0 align.w outtext: blk.l 128,0 end 6.5.Disk Operations. -------------------- The most important peripheral device for a computor like the Amiga is the disk drive.You use it to save data,so that you don't lose it when you turn off the computor.We'll look at saving and retrieving data in this chapter. Lets first look at the simple disk operations that are used for data management.To gain access to a file,you must open it first. This is done using the OPEN function from the DOS library,a function that you're already familiar with.I'll assume in the following examples,that you've already opened the DOS library. 6.5.1.Open Files. ----------------- The open function needs a parameter for the mode.The mode has a particular meaning.If the file is opened for reading,it must already exist.The mode for the OPEN function must be "old"(1005) in this case. If you want to produce a file,you must open it first.Since it does not exist,you use the "new"(1006) mode.If a file is opened for writing using this mode even though a file with this name already exists,the old file with this name is erased and replaced.To avoid loss of data,you should check if a file by that name already exists and then output an error message if it does. You're going to start with a subroutine that opens a file.Lets assume that the filename starts at the label "filename",and that it is closed with a null byte.You just need to pass the mode in register D2. The routine puts the file handle number in "filehd"and returns to the main program.Since the operation with the handle is the last one performed by the subroutine,the status of the operation can be evaluated once the return has been executed.If the operation went smoothly and the file is opened,the handle number has a non-zero value.If it is zero and "bsr openfile"is followed by "beq error", you can branch to an error handling routine when problems occur. Here is a subroutine for opening and closing a file: open =-30 ; (6.5.1A) close =-36 mode_old = 1005 mode_new = 1006 ... openfile: ;*open file,mode in D0 move.l dosbase,a6 ;DOS base address in A6 move.l #filename,d1 ;pointer to filename jsr open(a6) ;open file move.l d0,filehd ;save handle rts closefile: ;*close file move.l dosbase,a6 ;DOS base address in A6 move.l filehd,d1 ;file handle in D1 jsr close(a6) ;close file rts filehd: dc.l 0 ;storage for file handle filename: dc.b "filename",0 ;file to be opened align ;even To use these subroutines,you must look at how you can load and save data. 6.5.2.Reading and Writing Data. ------------------------------- Lets write a new file.To start,write the following lines: move.l #mode_new,d2 ;open new file (6.5.2A) bsr openfile ;open file beq error ;did'nt work! For the filename,write a name like "Testfile"in the line labelled "filename".After calling the "openfile"routine,a file with this name is created on the disk.If one existed already,it is erased. Lets assume you want to write a short text file.For the example lets use: text: dc.b "This is a test text for the Testfile",0 textend: The "textend"label is used so that you can calculate the number of data bytes by subtracting "text". You want to write this text in the file.Use the WRITE function which needs three parameters: In D1 the file handle that you got back from the OPEN function. In D2 a pointer to the data that should be written. In D3 the number of bytes to be written. For the example,you'll need another segment of code to put the pointer to the data in D2 and the number of bytes in D3: write =-48 ; (6.5.2B) ... writedata: ;*write data in the file move.l dosbase,a6 ;DOS base address move.l filehd,d1 ;file handle in D1 jsr write(a6) ;write data rts After opening the file,you can call the subroutine from the main program with the following lines: move.l #text,d2 ;pointer to data move.l #textend-text,d3 ;number of bytes bsr writedata ;write data in the file Then close the file with: bsr closefile ;close file bra end ;end program After running the program,look at the directory of the diskette, you should find the file "testfile".It is just as long as your text.You want to read this file in,to make sure it contains the right data. You need the DOS function READ,which needs the same parameters as the WRITE function.You can use parameters for the number of bytes to read just part of the file.If you give a larger number than the file contains,the whole file is loaded.You'll find the number of bytes read in D0. Lets set up a field that as enough space for the data you want to read.You can do this with the following line: field: blk.b 100 ;reserve 100 bytes For the example data,this is plenty.If you want to load another file,you may need to reserve more space. Now lets write a subroutine to read the data.You always want to load whole files.You just need to pass the address of the buffer so the data is loaded into the subroutine.In the example,its the address "field". Heres the subroutine that reads the entire opened file into the memory area pointed to by D2: read = -42 ; (6.5.2C) ... readdata: ;*read file move.l dosbase,a6 ;DOS base address in A6 move.l filehd,d1 ;file handle in D1 move.l #$ffffff,d3 ;read an arbitrary number of bytes jsr read(a6) ;read data rts To use this routine to load the file into the buffer "field",use the following main program: move,l #mode_old,d2 ;old file bsr openfile ;open file beq error ;did'nt work! move.l #field,d2 ;pointer to data buffer bsr readdata ;read file move.l d0,d6 ;save number of bytes in D6 bsr closefile ;close file bra end ;program end After assembling and starting this program,you can use the debugger to look at the data buffer that you filled with data from the file.In D6,you'll find the number of bytes that were read from the file. 6.5.3.Erase Files. ------------------ Once you've experimented enough with the program above,you'll certainly want to erase the "Testfile"file.The DELETEFILE function in the DOS library has an offset of -72.It only needs 1 parameter. The parameter is passed in D1.The parameter is a pointer to the filename.The name must be closed with a null byte. To erase "Testfile",use the following lines: deletefile =-72 ; (6.5.3) ... move.l dosbase,a6 ;DOS base address in A6 move.l #filename,d1 ;pointer to filename in D1 jsr deletefile(a6) ;erase file The file is deleted.You can't save the file with normal methods if you accidently erase it!You can use a trick that saves the data. We'll take a look at this trick later.Its used in lots of programs 6.5.4.Rename Files. ------------------- When a text editing program writes a text that as be altered back to the disk,the old file usually isn't erased.Often the old file is renamed.For example,it might get the name "Backup".The new file is written to disk with the old name. The function in the DOS library that allows you to change the names of programs is called RENAME and has -78 as an offset.You need to pass two parameters-D1 as a pointer to the old name and D2 as a pointer to the new name of the file. To rename "Testfile"as "Backup"(before you erase it),use the following lines: rename =-78 ... move.l dosbase,a6 ;DOS base address in A6 move.l #oldname,d1 ;pointer to old name in D1 move.l #newname,d2 ;pointer to new name in D2 jsr rename(a6) ;rename file ... oldname: dc.b "testfile",0 newname: dc.b "backup",0 6.5.5.CLI Directory. -------------------- Lets pretend you've programmed a text editor and started it.Now you want to load a text from disk and edit it-but whats the name of that file? You need a function to read and display the directory of the disk. There are several ways to do this.First lets use the easiest method.It doesn't require much programming and can be quite useful. The trick is to call the Dir or List programs that are in the C directory.You'll use the CLI commands.The DOS library contains a command called "Execute"with offset -222 that allows you to execute CLI commands. The function needs three parameters: In D1 a pointer to a string closed with a zero that contains the name of the command to be executed.This string must contain the same command that you would give in the CLI.It can be a null pointer as well. In D2 the input file is determined.Normally theres a zero here. If however,you give the file handle of a text file,though, this file is read and interpreted as a command sequence.If you define a window as the input medium,you've programmed a new CLI window! In D3 the output file is determined.If there a zero here,the output of the commands (for example,DIR output) is sent to the standard CLI window. To try this out,insert this subroutine in a program that has already opened the DOS library and a window. execute = -222 ; (6.5.5) ... dir: move.l dosbase,a6 ;DOS base address in A6 move.l #command,d1 ;pointer to command line clr.l d2 ;no input (CLI window) move.l conhandle,d3 ;output in our window jsr execute(a6) ;execute command rts command: dc.b "dir",0 This program works with the List command as well.The disadvantage of this method is that the disk that the Workbench is loaded from must be in the drive or the system requests you to put it in.The Dir command is just a program,and the Amiga must load it before it can run. The disadvantage isn't too great.The program is short,and it allows you to use any CLI command in a program. Here is the complete program in AssemPro format that calls the dir program: ;***** 6.5.5A DIR.ASM S.D.***** openlib =-408 closelib =-414 ;execbase = 4 ;defined in AssemPro ;macros *calls to Amiga Dos: open =-30 close =-36 execute =-222 IoErr =-132 mode_old = 1005 alloc_abs =-$cc ILABEL AssemPro:includes/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bra test ;system test init: ;system initialization and ;open move.l execbase,a6 ;number of execute-library lea dosname(pc),a1 moveq #0,d0 jsr openlib(a6) ;open DOS-library move.l d0,dosbase beq error lea consolname(pc),a1 ;console definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts test: bsr dir ;do directory bra qu ;quit and exit dir: move.l dosbase,a6 ;DOS base address in A6 move.l #command,d1 ;pointer to command line clr.l d2 ;no input (CLI window) move.l conhandle,d3 ;output in our window jsr execute(a6) ;execute command rts error: move.l dosbase,a6 jsr IoErr(a6) move.l d0,d5 move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;DOS.Lib close move.l execbase,a6 jsr closelib(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-Definition- ;text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts dosname: dc.b 'dos.library',0,0 align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/** CLI-Test **',0 align.w conhandle: dc.l 0 command: dc.b "dir",0 end 6.5.6.Read Directory. --------------------- Now,lets look at another method that doesn't need the CLI.In this way,you can read the directory of any disk without having to play Disk Jockey. You need to writ a program that does what CLI's Dir program does. There are several steps. First you must give the system a key to the desired directory.That means you must call DOS'Lock function.It needs two parameters: In D1 pass a pointer to a text that contains the name of the directory you wish to read.If,for example,you want to read the contents of the RAM disk,the text would be 'RAM:',0. In D2 put the mode that determines whether to read or write.Let us use the "Read"(-2) mode. You call the Lock function (offset -84) and get either a point to the key or a zero returned to you in the D0 register.If you get a zero,the call did'nt work,the file was'nt found.This function can be used to find if a file is on the disk.You use this function with the name and see if D0 comes back zero.If not,the file exists. Lets assume the file or path exists.You need to save the value that came back in D0.You'll need it for both functions that you'll call. The next function you need is called Examine.You use it to search the disk for an acceptable entry.It returns parameters like name, length and date that correspond to the entry.You need to reserve a memory block for this information and put the beginning of the block in D2 before calling the Examine function.Put the key you got from the Lock function in the D1 register. The memory area that is filled with information is called a FileInfoBlock.Its 260 bytes long and contains information about the file.The name starts in the 9th byte and ends with a null byte so you can easily print it with our "pmsg"routine.The information that Examine gives isn't about a particular file,but about the disk.The name in FileInfoBlock is the disk name. The Examine function sends the status back in the D0 register. Since the Lock function already tested if the file existed,evalua- ting the status really isn't necessary. Now to the function that you can use to read individual files from the directory.The function is called ExNext (Examine Next).This function searches for the next entry that fits the key every time it is called.ExNext gets the same parameters as Examine gets. However,the return parameter in D0 is more important here. The ExNext function is always called in the same way.It always gets the next entry of the directory.If no more entries exist in the directory,ExNext puts a zero in the D0 register. You need to continue performing this operation until there aren't any more entries.You can find this using the IoErr function from the DOS library. This function doesn't need any parameters.It returns the status of the last I/O operation that was performed in the D0 register.After the last ExNext,this value is 232,which means no_more_Entries. Heres a complete routine for reading the directory of the disk in DFO:and displaying the contents in the window. ; 6.5.5B.ASM ;***** DOS-Sample function 3/87 S.D. ***** openlib =-30-378 closelib =-414 exbase =4 * calls to amiga dos: open =-30 close =-30-6 read =-30-12 write =-30-18 myinput =-30-24 output =-30-30 currdir =-30-96 lock =-30-54 examine =-30-72 exnext =-30-78 exit =-30-114 IoErr =-30-102 waitforch =-30-174 mode = 0 mode_old = 1005 mode_new = 1006 alloc_abs =-$cc free_mem =-$d2 ILABEL AssemPro:includes/Amiga.l ;AssemPro only INIT_AMIGA ;AssemPro only run: bsr init ;initialization bra test ;system-test init: ;system initialization and ;open move.l exbase,a6 ;pointer to exec.library lea dosname(pc),a1 moveq #0,d0 jsr openlib(a6) ;open dos-library move.l do,dosbase beq error lea consolname(pc),a1 ;console definition move.l #mode_old,d0 bsr openfile ;console open beq error moveq d0,conhandle rts test: move.l #mytext,d0 bsr pmsg ;test-text output move.l dosbase,a6 move.l #name,d1 move.l #-2,d2 jsr lock(a6) move.l d0,d5 tst.l d0 beq error move.l d0,locksav move.l dosbase,a6 move.l locksav,d1 move.l #fileinfo,d2 jsr examine(a6) move.l d0,d6 tst.l d0 beq error loop: move.l dosbase,a6 move.l locksav,d1 move.l #fileinfo,d2 jsr exnext(a6) tst.l d0 beq error move.l #fileinfo+8,d0 bsr pmsg bsr pcrlf bra loop error: move.l dosbase,a6 jsr ioerr(a6) move.l d0,d6 move.l #presskey,d0 bsr pmsg bsr getch move.l #-1,d7 ;flag qu: move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;dos.lib close move.l exbase,a6 jsr closelib(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to I/O-Definition- ;Text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts pmsg: ;print message (D0) movem.l d0-d7/a0-a6,-(sp) move.l d0,a0 move.l a0,d2 clr.l d3 mess1: tst.b (a0)+ beq mess2 addq.l #1,d3 bra mess1 mess2: move.l conhandle,d1 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 rts pcrlf: move #10,d0 bsr pchar move #13,d0 pchar: ;character in D0 output movem.l d0-d7/a0-a6,-(sp) ;save all move.l conhandle,d1 pch1: lea chbuff,a1 move.b d0,(a1) move.l a1,d2 move.l #1,d3 move.l dosbase,a6 jsr write(a6) movem.l (sp)+,d0-d7/a0-a6 ;restore all rts scankey: ;test key move.l conhandle,d1 move.l #500,d2 ;wait value move.l dosbase,a6 jsr waitforch(a6) tst.l d0 rts readin: ;input from keyboard movem.l d0-d7/a0-a6,-(sp) ;registers lea inline+2,a2 ;pointer to input buffer clr.l (a2) inplop: bsr getchr cmp.b #8,d0 beq backspace cmp.b #127,d0 ;delete? beq backspace bsr pchar ;character output cmp.b #13,d0 beq inputx move.b d0,(a2)+ bra inplop input: clr.b (a2)+ sub.l #inline,a2 move a2,inline ;length in inline+1 movem.l (sp)+,d0-d7/a0-a6 ;registers rts backspace: cmp.l #inline,a2 ;at beginning? beq inplop ;yes move.b #8,d0 bsr pchar ;backspace move #32,d0 bsr pchar ;blank move #8,d0 bsr pchar ;backspace clr.b (a2) subq.l #1,a2 bra inplop getchr: ;get 1 character from keyboard move.l #1,d3 ;1 character move.l conhandle,d1 lea inbuff,a1 ;buffer-address move.l a1,d2 move.l dosbase,a6 jsr read(a6) clr.l d0 move.b inbuff,d0 rts mytext: dc.b 'Directory of Diskette: DFO:',10,13,10,13,0,0 dosname: dc.b 'dos.library',0,0 presskey: dc.b 'Press thr Return key!!',0 align.w dosbase: dc.l 0 consolname: dc.b 'CON:0/100/640/100/** Directory-Test **',0 name: dc.b 'DFO:',0 align.w locksav: dc.l 0 fileinfo: ds.l 20 conhandle: dc.l 0 inbuff: DS.B 8 inline: DS.B 180 chbuff DS.B 82 end The FileInfoBlock contains the following entries: Offset Name Meaning ---------------------------------------------------------------- 0 DiskKey.L Disk Number 4 DieEntryType.L Entry Type (+=Directory,-=File) 8 FileName 108 bytes with the filename 116 Protection.L File Protected? 120 EntryType.L Entry type 124 Size.L Length of file in bytes 128 NumBlocks.L Number of blocks 132 Days.L Creation day 136 Minute.L Creation time 140 Tick.L Creation time 144 Comment 116 bytes with comments If you want to have the program output the file length as well,you can read the length with "move.l fileinfo+124,d0"and then use a conversion routine to produce a decimal number.You can output this result with the name. 6.5.7.Direct Access To Disk. ---------------------------- There isn't a simple function in the library for accessing single disk sectors.Here,you must work with a device just like you did with speech output.This time you'll be working with the trackdisk. device. You want to work with this device to directly program the disk drives.Once you've built up the necessary program machinery,you can experiment with various commands for disk access.Remember that an error can cause the disk to be modified and thus unusable.Make sure you're using a non-essential disk.Don't use one which contains your only copy of something. The initialization here is similar to that for speech output.Here is the initialization routine for your program: ;** Direct disk access via trackdisk.device ** (6.5.7) openlib =-408 closelib =-414 execbase = 4 open =-30 close =-36 opendevice =-444 closedev =-450 sendIo =-462 read =-30-12 write =-30-18 waitforch =-30-174 mode_old = 1005 run: bsr init ;initialization bra test ;system-test init: ;initialize and open system move.l execbase,a6 ;pointer to exec.library lea dosname,a1 moveq #0,d0 jsr openlib(a6) ;open dos.library move.l d0,dosbase beq error lea diskio,a1 ;pointer to disk I/O area move.l #diskrep,14(a1) ;pointer to port clr.l d0 ;drive 0 (built in) clr.l d1 ;no flags lea trddevice,a0 ;pointer to device name jsr opendevice(a6) ;open trackdisk.device tst.l d0 ;error? bne error ;yes! move.l #consolname(pc),d1 ;console definition move.l #mode_old,d2 ;old mode move.l dosbase,a6 ;dos base address jsr open(a6) ;open window tst.l d0 ;error? beq error ;yes! move.l d0,conhandle ;else save handle rts ;done test: ;place for test routine And now for the functions that take care of the various messages at the end of the program. error: move.l #-1,d7 ;flag for error (for SEKA) qu: move.l execbase,a6 ;exec base address lea diskio,a1 ;pointer to disk I/O move.l 32(a1),d7 ;IO_ACTUAL in D7 (for testing) move #9,28(a1) ;command motor on/off move.l #0,36(a1) ;0=off,1=on,so turn motor jsr sendio(a6) ;off move.l conhandle,d1 ;close window move.l dosbase,a6 jsr close(a6) move.l dosbase,d1 ;close dos.lib move.l execbase,a6 jsr closelib(a6) lea diskio,a1 jsr closedev(a6) ;close trackdisk.device rts Lets not forget the routine that waits for the user to press ,so that you can watch the effects of the test function in peace: getchr: ;get a character from keyboard move.l #1,d3 ;1 character move.l conhandle,d1 ;window handle move.l #inbuff,d2 ;buffer address move.l dosbase,a6 ;dos base address jsr read(a6) ;read character rts ;thats it The last thing you need is the section of code that declares the text and data fields that your program needs: dosname: dc.b 'dos.library',0 align consolname: dc.b 'RAW:0/100/640/50/** Wait window',0 align trddevice: dc.b 'trackdisk.device',0 align dosbase: dc.l 0 ;dos base address conhandle: dc.l 0 ;window handle inbuff: blk.b 80,0 ;keyboard buffer diskio: blk.l 20,0 ;I/O structure diskrep: blk.l 8,0 ;I/O port diskbuff: blk.b 512*2,0 ;place for 2 sectors There,now you've done with the set up work.Lets look at how you can give commands to the disk drives.The first and easiest command is the one for turning the drive motor on and off.You've already seen this command in the program.This is command number nine.This number goes in the command word of the I/O structure (bytes 28 and 29 of the structure). You need to pass a parameter that lets the computor know whether to turn the motor off or on.This information goes in the I/O long word that starts at byte 36:its zero for off,and one for on. You already chose the motor that should be turned on or off when you opened the device.You put the number of the chosen disk drive in D0-in your case you put a zero there because you are using the DFO:disk drive. Heres an overview of the commands you can use to access information on the disk: No Name Function ----------------------------------------------------------------- 2 READ Read one or more sectors 3 WRITE Write sectors 4 UPDATE Update the track buffer 5 CLEAR Erase track buffer 9 MOTOR Turn motor on/off 10 SEEK Search for a track 11 FORMAT Format tracks 12 REMOVE Initialize routine that is called when you remove the disk 13 CHANGENUM Find out number of disk changes 14 CHANGESTATE Test if disk is in drive 15 PROTSTATUS Test if disk is write protected You've already learned about command number nine.Lets look at the three commands you can use to make tests.These are the last three commands.They put a return value in the long word that begins in the 32nd byte in the I/O structure.This value was written in D7 in the program above for testing purposes.You can read its contents directly if you ran the program with AssemPro. Here is a simple routine that you can use to run one of these commands with: test: ; (6.5.7B) lea diskio,a1 ;pointer to I/O structure move #13,28(a1) ;pass command (for example 13) move.l execbase,a6 ;execbase address in A6 jsr sendio(a6) ;call function If CHANGENUM (command 13) is executed,in D7 you'll get the number of times a disk was taken out and put in the drive.If you call the program,you'll get a value back.If you take the disk out and put it back in,the number is two higher the next time you call the program. The CHANGESTATE command (command 14) tells whether a disk is in the drive or not.If one is,a zero comes back.Otherwise,a $FF is returned. You get the same values back from the PROTSTATUS function (command 15).Here a zero means that the disk isn't write protected,while $FF means that it is. Now lets look at the READ and WRITE functions.These operations need a few more parameters than the status functions.You need to pass the following parameters: The address of the I/O buffer in the data pointer,the number of bytes to be transfered in I/O length,and the data address on the disk in I/O offset. The number of data bytes must be a multiple of 512,since every sector is 512 bytes,and only whole sectors can be read. The data address is the number of the first byte in the sector.If you want to use the first sector,the offset is zero.For the second sector,its 512,etc...The formula is: offset = (sector_number -1) *512 Here is a routine that loads the first two sectors of the disk into the buffer: test: (6.5.7C) lea diskio,a1 move #2,28(a1) ;command:READ move.l #diskbuff,40(a1) ;buffer move.l #2*512,36(a1) ;length:2 sectors move.l #0*512,44(a1) ;offset:0 sectors move.l execbase,a6 ;exec base address jsr sendio(a6) ;start function Start the program from the debugger and then look at the buffers contents after the program ends.You can find out the format of the disk here.If you want to read a sector thats being used,change the 0 in the offset definition to 700 and start again.Its highly probable that theres some data there. To modify and write back the data that you've read from the disk, you need command number three,the WRITE command.The parameters are the same. If you've executed the WRITE commandyou're probably wondering why the disk light did'nt go on.Thats because the Amiga writes a track that as been read into a buffer on its own.It WRITE's data there as well.It won't write the data to disk until another track is accessed. You can have the data updated directly as well using command four, the UPDATE command. Command 11,the FORMAT command,is also quite interesting.This command needs a data field that is 11*512=5632 bytes long-the length of a track.The offset must be a multiple of this number so that you start at the beginning of a track. The length must be a multiple of 5632 as a result.If several tracks are formatted,each track is filled with the same data. You can use this function to easy write a disk copy program.You READ the source disk and then FORMAT the corresponding track on the destination disk.Thats how the DiskCopy program works-it reformats the destination disk. Command ten,the SEEK command,just needs the offset.It moves the Read/Write head of the drive to the position specified without making a disk access or testing if its at the right position. Command 12,the REMOVE command,is used to install an interrupt routine that is called when the disk is removed from the disk drive.The address of the interrupt structure is passed in the data pointer of the I/O structure.If theres a zero here,the interrupt routine is turned off. Heres a complete example program in AssemPro format: ;***** Track disk-Basic function 10/86 S.D. ***** ILABEL ASSEMPRO:includes/Amiga.l :AssemPro only openlib =-30-378 closelib =-414 ;execbase = 4 ;defined in INIT_AMIGA * calls to amiga dos: open =-30 close =-30-6 opendevice =-444 closedev =-450 sendIo =-462 read =-30-12 write =-30-18 waitforch =-30-174 mode_old = 1005 INIT_AMIGA ;AssemPro only run: bsr init ;initialization bra test ;system test init: ;system initialization and ;open move.l execbase,a6 ;pointer to exec-library lea dosname,a1 moveq #0,d0 jsr openlib(a6) ;open dos-library move.l d0,dosbase beq error lea diskio,a1 move.l #diskrep,14(a1) clr.l d0 clr.l d1 lea trddevice,a0 jsr opendevice(a6) ;open trackdisk.device tst.l d0 bne error bp: lea consolname(pc),a1 ;console-definition move.l #mode_old,d0 bsr openfile ;console open beq error move.l d0,conhandle rts test: bsr accdisk bsr getchr ;wait for character bra qu error: move.l #-1,d7 ;flag qu: move.l execbase,a6 lea diskio,a1 move #9,28(a1) move.l #0,36(a1) jsr sendio(a6) move.l conhandle,d1 ;window close move.l dosbase,a6 jsr close(a6) move.l dosbase,a1 ;dos.lib close move.l execbase,a6 jsr closelib(a6) lea diskio,a1 move.l 32(a1),d7 jsr closedev(a6) EXIT_AMIGA ;AssemPro only openfile: ;open file move.l a1,d1 ;pointer to the I/O-definition ;text move.l d0,d2 move.l dosbase,a6 jsr open(a6) tst.l d0 rts scankey: ;test for key move.l conhandle,d1 move.l #500,d2 ;wait value move.l dosbase,a6 jsr waitforch(a6) tst.l d0 rts getchr: ;get one character from ;keyboard move.l #1,d3 ;1 character move.l conhandle,d1 lea inbuff,a1 ;buffer-address move.l a1,d2 move.l dosbase,a6 jsr read(a6) clr.l d0 move.b inbuff,d0 rts accdisk: lea diskio,a1 move #2,28(a1) ;command:READ move.l #diskbuff,40(a1) ;buffer move.l #2*512,36(a1) ;length:2 sectors move.l #20*512,44(a1) ;offset: n sectors move.l execbase,a6 jsr sendio(a6) rts dosname: dc.b 'dos.library',0,0 align.w dosbase: dc.l 0 consolname: dc.b 'RAW:0/100/640/100/** Test-Window S.D.V0.1',0 trddevice: dc.b 'trackdisk.device',0 align.w conhandle dc.l 0 inbuff: ds.b 8 diskio: ds.l 20,0 diskrep: ds.l 8,0 diskbuff: ds.b 512*2,0 end Chapter 7. ---------- 7.Working With Intuition. ------------------------- Now that you've learned so much about machine language,lets look at the special features of the Amiga.Lets look at the operating system Intuition that is in charge of windows,screens,the mouse and lots of other things.Beforetaking a look at these beautiful features,theres some bad news. First,though,lets here the good news.Since Intuition has so many functions,it allows you to be very creative in programming your ideas.The disadvantage is that the flexibility means that you have to use a lot of parameters,and that makes for a lot of tedious work. However,this is no grounds for panic.Once you've built up the necessary routines,the programming and experimentation becomes increasingly interesting.Before you try out new program variations you should save your source code to disk,because Intuition gets fairly upset about bad parameters and often responds by crashing the system. Now lets get to work.To start working with Intuition,you need the Intuition library.You can load it with the OpenLibrary function from the EXEC library.Heres the subroutine that takes care of initialization. openlib =-408 execbase = 4 run: bsr openint ;load intuition library ... openint: ;*initialize and open system move.l execbase,a6 ;exec base address lea intname,a1 ;name of intuition library jsr openlib(a6) ;open intuition move.l d0,intbase ;save intuition base address rts intname: dc.b "intuition.library",0 align intbase: dc.l 0 ;base address of intuition When your program is finished,you need to close the screens,the window and the library.To do this,use the CloseLibrary function from the EXEC library.It has an offset of -414. Heres the subroutine: closelibrary =-414 ... closeint: ;*close intuition move.l execbase,a6 ;exec base address in A6 move.l intbase,a1 ;intuition base address in A1 jsr closelibrary(a6) ;close intuition rts ;done Now that you've got that taken care of,you can finally start working with Intuition. 7.1.Open Screen. ---------------- Intuition is a graphics operating system.For this reason,you'll be working with the screen.Its even more interesting to work with several screens at the same time.However,you only have one monitor on the Amiga. You can open as many screens as you like (at least,as long as theres some memory available).You can open a window,display menus and do I/O's there.The individual screens are fully independant. You can work with all of them simultaneously on the monitor. You can move individual screens forward and back to your hearts content.You can also press the left key and then an "m"to return to the workbench screen after getting into the different screens. You want to begin programming Intuition by setting up a screen.You have already loaded the Intuition library,so you can use the Open- Screen function. Wait a minute!What should the screen look like,where should it go, and what form should it have?You need to look at the options for the form of the screen you have available. The input to the screen is in the form of a table that has 13 entries.Lets take a look at the parameters that you need for our screen. You'll start the table with the label "screen_defs"which must be at an even address: align screen_defs: ;The screen table begins here The first bit of information that the screen needs is the position and size.Lets have it start in the upper left corner and fill the entire screen.You'll use the positions X=0 and Y=0,the width 320 and the height 200.This means that your screen is the maximum size. x_pos: dc.w 0 ;X-Position y_pos: dc.w 0 ;Y-Position width: dc.w 320 ;width height: dc.w 200 ;height Next you need to decide which colors should be displayed.That depends on the number of bitplanes,on the depth.Lets choose two. That means you have 2^2 (4) colours available.Lets choose two, since four colours is usually plenty. depth: dc.w 2 ;number of bitplanes Next you need to choose the colour of the title line and the function symbols.Give the number of the colour register: detail_pen: dc.b 0 ;colour of text,etc... Now for the colour of the text background: block_pen dc.b 1 ;background colour Make sure that these two inputs fit in a byte.The colours are normally the following (if the standard values have'nt been changed).You'll notice that the number of colours depends on the number of bit maps. Pen Colour --------------------------------------------------------- 0 Background (blue) 1 White for two bit planes 2 Black 3 Red for three bit planes 4 Blue 5 Violet 6 Turquoise 7 White for four bit planes 8 Black 9 Red 10 Green 11 Brown 12 Blue 13 Blue 14 Green 15 Green The next word contains the bits that describe the appearance of the screen.The bits are: Bit Value Name Meaning --------------------------------------------------------------- 1 2 GENLOCK_VIDEO 2 4 INTERLACE Puts the screen in Interlace mode.The resolution and thus the maximum screen size are doubled. 6 $40 PFBA 7 $80 EXTRA_HALFBRITE 8 $100 GENLOCL_AUDIO 10 $400 DBLPF Divides the screen into a border and character area. 11 $800 HOLDNMODIFY Turns on Hold-and-Modify mode. 13 $2000 VP_HIDE 14 $4000 SPRITES Allows sprites to be used. 15 $8000 MODE_640 Turns on the highest resolution graphics for the screen(640x400). Choose the value two (normal) for your example screen: view_modes: dc.w 2 ;representation mode The following word is constructed in such away that each bit as its own meaning.Use this to set what sort of screen it is.Choose 15 so the screen is a "Custom screen",which allows you all of the options. screen_type: dc.w 15 ;screen type:custom screen Next theres a pointer to the character set to be used for all output to the screen.If you don't want to install your own character set,just put a zero here,and the standard character set is used. font: dc.l 0 ;character set:standard Next theres a pointer to the text thats used as the name of the screen.The text ends with a zero,just like window names must. title: dc.l name ;pointer to title text Next comes a long word that defines the gadgets.These gadgets represent the functions,like "Bring forward",that can be accessed via a mouse click in the screen.The long word in this table is a pointer to a list which specifies the gadgets.These aren't the system gadgets.However,you're only using system gadgets here,so put a zero here. gadgets: dc.l 0 ;no gadgets Finally theres a long word that you only need if you want to use the special bitmap just for your screen.Since this isn't the case, just put a zero here. bitmap: dc.l 0 ;no bitmap Thats it for the list entries that you need to define the screen. You still need the text for the name of the screen.Enter the following: sname: dc.b 'Our Screen',0 ;screen title Heres a quick overview of the list: align screen_defs: ;*The screen ta x_pos: dc.w 0 ;X-position y_pos: dc.w 0 ;Y-position width: dc.w 320 ;width height: dc.w 200 ;height depth: dc.w 2 ;number of bitplanes detail_pen: dc.b 0 ;colour of the text,etc... block_pen: dc.b 1 ;background colour view_modes: dc.w 2 ;representation mode screen_type: dc.w 15 ;screen type:custom screen font: dc.l 0 ;character set:standard title: dc.l sname ;pointer to title text gadgets: dc.l 0 ;no gadgets bitmap: dc.l 0 ;no bit map sname: dc.b 'Our Screen',0 ;screen title Once you've decided on the parameters,its very easy to open the screen.You need Intuitions OpenScreen function.Its offset is -198 and it only needs one parameter,the address of the parameter table.The program fragment looks like this: openscreen =-198 bsr openint ;open intuition bsr scropen ;open screen ... scropen: ;*open screen move.l intbase,a6 ;intuition base address in A6 lea screen_defs,a0 ;pointer to table jsr openscreen(a6) ;and open move.l d0,screenhd ;save screen handle rts ;return to main program ... screen_defs: ;table info follows Now the Amigas Workbench screen is covered by your screen.Now you can do what you want with it until the program is done.Afterwards, the screen must be closed again,so that you can see the Workbench screen again. Use the CloseScreen function (offset -66) to do this.The only parameter it needs is the pointer to the screen structure you got back from the OpenScreen function. closescreen =-66 ... scrclose: ;* close screen move.l intbase,a6 ;intuition base address in A6 move.l screenhd,a0 ;screen handle in A0 jsr closescreen(a6) ;clos screen rts ;done The long word that OpenScreen returned to you is a pointer to a screen structure that contains all the needed data about the screen.Besides the data which was given,there is a pointer in the screen area for individual bit planes,etc... The form of this structure is fairly complicated and contains some data that you can't use.Several of the parameters are interesting, however.Heres a selection of usable parameters: No Name Function ------------------------------------------------------------------ 0 (NextScreen.L) Pointer to next screen. 4 (FirstWindow) Pointer to first window structure 8 (LeftEdge.W) $A (TopEdge.W) Position of screen $C (Width.W) Width $E (Height.W) Height $10 (MouseY.W) $12 (MouseX.W) Mouse position in the screen $14 (Flags.W) Screen flags $16 (Title.L) Pointer to title text $1A (DefaultTitle) Pointer to normal title $28 (Font.L) Pointer to character set $C0 (Plane0.L) Pointer to bitplane 0 $C4 (Plane1.L) Pointer to bitplane 1 $C8 (Plane2.L) Pointer to bitplane 2 $CC (Plane3.L) Pointer to bitplane 3 An example of an application for the plane pointer is writing and using your own character routine.Next you want to move the address of the plane into an address register as follows: move.l screenhd,a5 ;screen pointer in A5 move.l $c0(a5),a5 ;bitplane 0-pointer in A5 If you want to try this,do the following: move.l screenhd,a5 ;screen pointer in A5 move.l $c0(a5),a5 ;bitplane 0-pointer in A5 move #$20,d0 ;Counter D0=$20 lop1: move d0,(a5) ;write counter bits in picture add.l #80,a5 ;address+80,next line dbra d0,lop1 ;continue until D0 < 0 This program draws a white,square pattern that corresponds to the bit pattern for the numbers $20 to 0.This isn't a particularly useful program,but it shows how easy it is to write from a machine language program directly to the screen.If you change the offset in the second line to $C4,the pattern is read. You can move the entire screen with the normal technique of moving the mouse pointer into the upper border and moving it up and down with the left mouse key depressed.You can do the same with a program. Lets move the screen without the mouse.Use the joystick for demonstration purposes.Put the joystick in port two.As you saw in the chapter on the hardware register,you can read memory location $DFF00C to find information about the joystick.You can find the direction the screen should be moved here. Moving the screen requires another Intuition function.You use the MoveScreen function which as an offset of -162 and needs three parameters to do this.The parameters are: In A0 the pointer to the screen structure that you got back in D0 when you opened the screen.(You saved it in "screenhd") In D1 the desired movement in the Y-direction,the vertical direction. In D0 the horizontal movement in the X-direction.The varient doesn't work so you can only move the screen vertically. Insert the following lines in your program: MoveScreen =-162 ... scrmove: ;*move screen D0 to the right ;and D1 down move.l intbase,a6 ;intuition base address in A6 move.l screenhd,a0 ;screen handle in A0 clr.l d0 ;no horizontal movement jsr movescreen(a6) ;move screen rts ;done Now your looking at a complete program that goes through the following steps: 1. Opens the Intuition library 2. Opens the screen 3. Moves the screen in the direction specified by the joystick in port two 4. Closes the screen when the fire button is hit 5. Closes the Intuition library 6. Ends Here is the complete program including the subroutines,so you'll have it all in one spot: ;** Demo program to open and move a screen ** movescreen =-162 openscreen =-198 closescreen =-66 closelibrary =-414 openlib =-408 ;open library execbase = 4 ;exec base address joy2 =$dff00c ;joystick 2 data fire =$bfe001 ;firebutton 2:bit 7 run: bsr openint ;open intuition bsr scropen ;open screen move joy2,d6 ;save joystick info loop: tst.b fire ;test fire button bpl ende ;pressed down:done move joy2,d0 ;basic info in D0 sub d6,d0 ;subtract new data cmp #$0100,d0 ;up? bne noup ;no move.l #-1,d1 ;dy=-1 direction y bsr scrmove ;move up bra loop noup: cmp #$0001,d0 ;down? bne loop ;no move.l #1,d1 ;dy=1 bsr scrmove ;move down bra loop ende: bsr scrclose ;close screen bsr closeint ;close intuition rts ;done! openint: ;*initialize and open system move.l execbase,a6 ;exec base address lea intname,a1 ;name of intuition library jsr openlib(a6) ;open intuition move.l d0,intbase ;save intuition base address rts closeint: ;*close intuition move.l execbase,a6 ;exec base address in A6 move.l intbase,a1 ;intuition base address in A1 jsr closelibrary(a6) ;close intuition rts ;done scropen: ;*open screen move.l intbase,a6 ;intuition base address in A6 lea screen_defs,a0 ;pointer to table jsr openscreen(a6) ;open move.l d0,screenhd ;save screen handle rts ;return to main program scrclose: ;*close screen move.l intbase,a6 ;intuition base address in A6 move.l screenhd,a0 ;screen handle in A0 jsr closescreen(a6) ;close screen rts ;done scrmove: ;move screen D0 right/D1 down move.l intbase,a6 ;intuition base address in A6 move.l screenhd,a0 ;screen handle in A0 clr.l d0 ;no horizontal movement jsr movescreen(a6) ;and move rts ;done align screen_defs: ;*screen table begins here x_pos: dc.w 0 ;X-position y_pos: dc.w 0 ;Y-position width: dc.w 320 ;width height: dc.w 200 ;height depth: dc.w 2 ;number of bitplanes detail_pen: dc.b 1 ;Text colour=white block_pen: dc.b 3 ;background colour=red view_modes: dc.w 2 ;representation mode screen_type dc.w 15 ;screen type:custom screen font: dc.l 0 ;standard character set title: dc.l sname ;pointer to title text gadgets: dc.l 0 ;no gadgets bitmap: dc.l 0 ;no bit map intbase: dc.l 0 ;base address of intuition screenhd: dc.l 0 ;screen handle intname: dc.b 'intuition.library',0 align sname: dc.b 'Our Screen',0 ;Screen title align end From this example,you can see how easy scrolling actually is. Another easy thing to do is to use the DisplayBeep function.It as an offset -96;the only parameter it needs is the screen pointer that you stored in the "screenhd"memory block.This function covers the screen with an orange colour for a short while.The screen is not changed.The beep function can be used as follows: DisplayBeep: =-96 ... move.l intbase,a6 ;intuition base address in A6 move.l screenhd,a0 ;screen pointer in A0 jsr displaybeep(a6) ;light up screen If you put a zero instead of a screen pointer in A0,the whole screen blinks. Good,now you have your own screen that you can move up and down. What good is it if you can't put anything on it?Lets open a window on the screen! 7.2.Open Window. ---------------- As you saw in the chapter on program initialization,its easy to open a window with the DOS library.You can't use this method on your own screen however.You need to use another method that can open any window on any screen. Intuition has a function called OpenWindow which handles this sort of work.It has an offset of -204 and needs only one parameter,a pointer to a window definition table.This pointer goes in register A0. This table is very similar to the one used to define the screen. The first four values specify the X-and Y-positions,the width,and the height of the window to be opened.Heres an example: align window_defs: dc.w 10 ;x-position dc.w 20 ;y-position dc.w 300 ;width dc.w 150 ;height Next come two bytes that define the colour of the letters on the background: dc.b 1 ;white letter colour dc.b 3 ;on a red background The next long word contains the IDCMP flags in its bits.The bits determine the circumstances under which Intuition sends a message to the program.The bits have the following meanings: Bit Value Name Meaning ----------------------------------------------------------------- 0 $000001 SIZEVERIFY 1 $000002 NEWSIZE Window size changed 2 $000004 REFRESHWINDOW 3 $000008 MOUSEBUTTONS Mouse key hit 4 $000010 MOUSEMOVE Mouse moved 5 $000020 GADGETDOWN A special gadget chosen 6 $000040 GADGETUP Same as above 7 $000080 REQSET 8 $000100 MENUPICK A menu item chosen 9 $000200 CLOSEWINDOW A window closed 10 $000400 RAWKEY A key pressed 11 $000800 REQVERIFY 12 $001000 REQCLEAR 13 $002000 MENUVERIFY 14 $004000 NEWPREFS Preferences modified 15 $008000 DISKINSERTED A disk put in 16 $010000 DISKREMOVED A disk taken out 17 $020000 WBENCHMESSAGE 18 $040000 ACTIVEWINDOW A window activated 19 $080000 INACTIVEWINDOW A window deactivated 20 $100000 DELTAMOVE Report relative mouse movement If you want your first window to respond only by clicking on the close symbol,write the following: dc.l $200 ;IDCMP flags:CLOSEWINDOW Next comes a long word whose bits determine the windows type.You can use this to construct a window to your exact specifications. This is quite different from windows opened with the DOS function. The bits mean: Bit Value Name Meaning ------------------------------------------------------------------ 0 $0000001 WINDOWSIZING Window size is changeable 1 $0000002 WINDOWDRAG Window is moveable 2 $0000004 WINDOWDEPTH Window covering is posible 3 $0000008 WINDOWCLOSE Window close symbol 4 $0000010 SIZEBRIGHT 5 $0000020 SIZEBOTTOM 6 $0000040 SIMPLE_REFRESH New drawing manuel 7 $0000080 SUPER_BITMAP Save the windows contents 8 $0000100 BACKDROP Move window back 9 $0000200 REPORTMOUSE Report mouse co-ordinates 10 $0000400 GIMMEZEROZERO 11 $0000800 BORDERLESS Window without border 12 $0001000 ACTIVATE Window active 13 $0002000 WINDOWACTIVATE 14 $0004000 INREQUEST 15 $0008000 MENUSTATE 16 $0010000 RMBTRAP Right mouse key:no menu 17 $0020000 NOCAREREFRESH No refresh message 24 $1000000 WINDOWREFRESH 25 $2000000 WBENCHWINDOW To refresh is to rebuild the window contents when necessary,for instance when the windows size is changed.If none of the refresh bits are set,you're in Smart-Refresh-Mode.In this case,Intuition takes care of refreshing the window.This is the easiest method. If you choose the value $100F as the type for your example window, the window is active once its opened,and it has all the system gadgets: dc.l $100F ;ACTIVATE and all gadgets The next long word in the list allows you to use your own gadgets in the window.This long word is a pointer to the structure of a your gadget.Since you don't want this,just put a zero here. dc.l 0 ;first gadget:no gadgets of our own The next long word is a pointer to a graphics structure so you can design your own symbol for checking menu points.Put a zero here. You'll use the standard sign: dc.l windowname ;pointer to window name The next long word is a pointer to the screen structure that you got back after calling the OpenScreen function.The easiest way to do this is to save the pointer to this location in the buffer: screenhd: dc.l 0 ;screen pointer The next long word is a pointer to a bit map if you want one of your own for the window.Since you don't want one,put a zero here. dc.l 0 ;no bit map of our own Next come four values that set the maximum and minimum width and height of the window: dc.w 150 ;smallest width dc.w 50 ;smallest height dc.w 320 ;maximum width dc.w 200 ;maximum height The last value in the list is the screen type of the screen the window is located in.Put a 15 here.You're using our screen as a custom screen: dc.w 15 ;screen type:custom screen Heres a quick overview of the whole list: align window_prefs: dc.w 10 ;X-position dc.w 20 ;Y-position dc.w 300 ;width dc.w 150 ;height dc.b 1 ;white print colour dc.b 3 ;on red background dc.l $200 ;IDCMP flags:CLOSEWINDOW dc.l $100f ;ACTIVATE and all gadgets dc.l 0 ;first gadget:no gadgets of ;our own dc.l 0 ;checkmark:standard dc.l windowname ;pointer to window name screenhd: dc.l 0 ;screen pointer dc.l 0 ;no bitmap of our own dc.w 150 ;smallest width dc.w 50 ;smallest height dc.w 320 ;maximum width dc.w 200 ;maximum height dc.w 15 ;screen type:custom screen ;and here comes the window name: windowname: dc.b 'Our Window',0 align Insert these lines in the program you listed above.Here are two subroutines for opening and closing the window: openwindow =-204 closewindow =-72 ... windopen: move.l intbase,a6 ;intuition base address in A6 lea windowdef,a0 ;pointer to window definition jsr openwindow(a6) ;open window move.l d0,windowhd ;save window handle rts windclose: move.l intbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;window handle jsr closewindow(a6) ;close window rts ... windowhd: dc.l 0 ;window handle Now you can insert a "bsr windowopen"after the "bsr scropen"and a "bsr windclose"before the "bsr scrclose"command.Once you've started the program,move the window around in the screen.You'll find that you can't move the window out of the screen with the mouse. The window in the example has the close gadget in the upper left corner.Normally if you click it,the window is closed.Try clicking it.You'll find that nothing happens. The display of this and all other gadgets,as well as other events must be programmed in,since Intuition doesn't know which action causes which event.We'll take a look at how to handle this in the next chapter. 7.3.Requesters. --------------- If you only have one disk drive,you've certainly seen the Amiga message,"Please insert xxx in unit 0",a lot.This window is another that has two fields for clicking.This sort of message with a choice of options is called a requester. You want to take a look at how to program a requester.First,you need a window for the requester to appear in.You opened a window of this sort in the example program. To display a requester,use the Intuition function AutoRequest (offset -348).It takes care of drawing and managing the requester. This function needs the following parameters: In A0 The pointer to the window structure that you put in "windowhd". In A1 A pointer to the text structure that should stand over the choice buttons. In A2 Same as above for the text of the left button. In A3 Same as above for the right button. In D0 The IDCMP flag which lets you know what event should go with the clicking of the left button. In D1 Same as above for the right button. In D2 The width of the whole requester. In D3 The height of the requester. Insert the following lines in your program: autorequest =-348 ... request: move.l windowhd,a0 ;pointer to window structure lea btext,a1 lea ltext,a2 ;pointer to text structure lea rtext,a3 move.l #0,d0 ;left activates by clicking move.l #0,d1 ;right activates by clicking move.l #180,d2 ;width and move.l #80,d3 ;height of requester move.l intbase,a6 ;intuition base address jsr autorequest(a6) ;display requester rts The flags passed in D0 and D1 offer some interesting posibilites. The system messages that tells you to enter a particular disk are overlooked when the DISKINSERTED flag is similar.Putting a disk in brings about the same responce as clicking the "Retry"button. Whats new is the use of a text structure.Use three of them.Text structures are lists that contain entries for the text that you need. These lists begin with two bytes that are used to define the colour.The first byte is the colour of the text.The second is for the background colour.Here this doesn't have any meaning. btext: dc.b 2 ;black text colour dc.b 0 ;background colour The next byte specifies the character mode.A zero means that the text is output normally.A four means the text is output inverted. dc.b 0 ;normal text representation The next entries are words.For this reason the addresses must be even,so you need to either insert another byte or use the "align" pseudo-op.The following words are the X-and Y-position of the text relative to the upper left corner of the requester. dc.w 10 ;X-position dc.w 5 ;Y-position relative to upper ;left corner Next,theres a pointer to the character set that is used.Put a zero here to use the standard set. dc.l 0 ;standard character set Next you need to give the address of the text that should be output.This text must be closed with a null byte. dc.l text ;pointer to text You need a long word at the end of the list that is either a pointer to another text or a zero if no more text is needed. dc.l 0 ;no more text Here are the three text structures that you need for the example: btext: ;text structure for the title dc.b 0,1 ;colour dc.b 0 ;mode align dc.w 10,10 ;text position dc.l 0 ;standard font dc.l bodytxt ;pointer to text dc.l 0 ;no more text bodytxt: dc.b "Requester Text",0 align ltext: ;text structure of left button dc.b 0,1 ;colour dc.b 0 ;mode align dc.w 5,3 ;text position dc.l 0 ;standard font dc.l lefttext ;pointer to text dc.l 0 ;no more text lefttext: dc.b "left",0 align rtext: dc.b 0,1 ;colour dc.b 0 ;mode align dc.w 5,3 ;text position dc.l 0 ;standard font dc.l righttext ;pointer to text dc.l 0 ;no more text righttext: dc.b "right",0 align After calling the requester,D0 contains the information about which of the buttons were pressed,and in which button the event took place.If D0 is zero,it was the right button.If it is one,it was the left button. 7.4.Event Handling. ------------------- Pretend you've opened a window that as a close symbol,and you want the program to react to this symbol being clicked.You need a signal from Intuition that lets you know that an event as taken place.The signal is called a message. The IDCMP flag of the window specifies which events should cause Intuition to send a message.By setting the bits for WINDOWCLOSE, you can allow a message to be sent when the close symbol is clicked. To get the message,you can use the EXEC function GetMsg (offset -372).It needs the source address of the event as a parameter.Here the source is the User port (which doesn't have anything to do with the User port on old Commodore computors). The User port contains a table which has entrieswhich specify the events that have taken place and related things like mouse position and time. How do you find the User port?Use the pointer to the window structure that you got back from the OpenWindow function and stored in the "windowhd"memory block. This pointer points to the window structure of this window.This structure consists of a number of entries.Some are copies of the parameters from our window definition table.We won't cover all the entries,because most won't be interesting to you.You're more interested in the pointer to the User port.Its in the window structure. You can find this in the long word that begins in the 86th byte of the structure.You can get this long word with the following lines of code: move.l windowhd,a0 ;pointer to structure in A0 move.l 86(a0),a0 ;user port pointer in A0 You can call the GetMsg function with this pointer in A0 by using the following lines of code in your program: GetMsg = -372 ... move.l windowhd,a0 ;pointer to structure in A0 move.l 86(a0),a0 ;user port pointer in A0 move.l execbase,a6 ;exec base address in A6 jsr getmsg(a6) ;get message This function returns a value in the D0 register.This value is a pointer to another structure,the Intuition Message Structure.If theres a zero in D0,no event as taken place. The long word that starts at the 20th byte in this structure contains the information about which event took place.Evaluating the information is easy,since the bits of this long word have the same meaning as the IDCMP flag that you described when you looked at opening windows. Put the lines above after "loop"and then insert the following: move.l d0,a0 ;message pointer in A0 move.l 20(a0),d6 ;save event in D6 tst.l d0 ;did the event take place? bne end ;yes! Now you can end this program by clicking the close symbol.This way you can find out if an event as taken place.You can use D6 to determine what event took place.In the example,D6 contains the number $00000200,which means that the close symbol was clicked. To see if this works with other events,change the $200 IDCMP flag to $10200 in the window definition table.When you've assembled and started this version,take the disk out of the drive-the program terminates. The IDCMP flags that you've got now cause the clicking of the close symbol and the taking out of the disk (DISKREMOVED) to be reported.If you want to find out which of the events took place, you can look in D6.It has a $200 in it if the window is closed,a $10000 if the disk was removed. 7.5.Menu Programming. --------------------- Now lets look at one of Intuitions more interesting capabillities: menu programming.By using menus,you can make your programs very user friendly. There are a lot of ways for you to use menus.You can make menu points unusable,output sub-menus,choose the type of menu entries (allow text or pictures to be output),etc..To have lots of options you need some parameters. Lets produce a menu with the SetMenuStrip function (offset -264) of Intuition.The function only needs two parameters,a pointer to the menu structure of the window to be drawn and a pointer to the window structure of the window in which the menu is to function. Each window can have its own menu that is active when the window is activated. Heres the subroutine to set up the menu: SetMenuStrip =-264 ... setmenu: ;* Initialize a menu move.l intbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;pointer to window structure lea menu,a1 ;pointer to menu structure jsr setmenustrip(a6) ;call function rts Heres a routine to erase the menu: ClearMenuStrip =-54 ... clearmenu: move.l intbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;pointer to window structure jsr clearmenustrip(a6) rts You've already got the pointer to the window structure.Lets look at the menu structure you need for the menu.You need to build a structure like this for each menu--for each menu title that appears when you press the right mouse key. This structure is a table with the following form: First there is a long word that points to the menu structure of the next menu.If the current menu is the last one,a zero goes here. align menu: dc.l menu1 ;pointer to the next menu Next come two words which contain tha X- and Y-position of the menu title: dc.w 20 ;X-position dc.w 0 ;Y-position Next,use two words to store the menu titles width and height in pixels: dc.w 50 ;width dc.w 10 ;height of menu title The next word contains the flag bit that determines whether the menu is available or not.An unavailable menu either as grey entries or they are drawn weakly.If the flag bit,bit 0,is set the menu is available.Otherwise,it is not. dc.w 1 ;menu available Now comes a long word which functions as a pointer to the text which is used as the menu title.Make sure the length isn't larger than the width entry allows!Otherwise unpleasent things will happen. dc.l menutext ;pointer to title text Next comes a long word which functions as a pointer to the structure of the first menu entry of this menu.Each menu entry needs its own structure. dc.l menuitem01 ;pointer to the first menu item The last entries in the table are four words that are reserved for internal functions.They must be here. dc.w 0,0,0,0 ;reserved words Thats the structure of the first menu.This structures first long word points to the next structure which has the same form.The pointer is set to zero in the last menu. You still need the structure of the menu entries.These structure tables have the following form: They start with a pointer to the next menu item.This pointer is set to zero for the last entry. align menuitem01: dc.l menuitem02 ;pointer to next menu item Next comes the four words:the X- and Y-position,the width and the height of the box the menu entry goes in.The size becomes obvious when the item is chosen by having the right mouse key clicked on it.Then the box becomes visible.As you can see,the next word is determined in the flags.First lets set the position and size of the menu point,though: dc.w 0 ;X-position of entry dc.w 0 ;Y-position dc.w 90 ;width in pixels dc.w 10 ;height in pixels The position entries are relative to the upper left corner of the menu that is pulled down. The following word was described above:it contains flags for entries to this menu item.There are several interesting variations possible.The following flag bits are contained in this word: Bit Value Name Meaning When Set ------------------------------------------------------------------ 0 $0001 CHECKIT Point is checked when chosen 1 $0002 ITEMTEXT Text menu item 2 $0004 COMMSEQ Choice can be made with keys as well 3 $0008 MENUTOGGLE Check turned on and off 4 $0010 ITEMENABLED Menu item available 6 $0040 HIGHCOMP Item inverted when chosen 7 $0080 HIGHBOX Iten framed when chosen 8 $0100 CHECKED Item is checked Heres a description of the bits: Name Description ------------------------------------------------------------------ CHECKIT If this bit is set,a check or a user-defined drawing is put in front of the text when the item is chosen.The text should begin with two blanks. ITEMTEXT The menu item is a normal text if this bit is set. Otherwise a drawing is output. COMMSEQ By setting this bit and entering a character,this menu point can be chosen by pressing the right key and the key that was input.The input character is then displayed in the menu with the Amiga symbol.There needs to be space available for this. MENUTOGGLE If this bit is set and checking is allowed (bit 0), the second time this point is chosen the check is erased,the next time it is displayed again,etc... ITEMENABLED Erasing this bit makes the menu item available. HIGHCOMP If this bit is set,the box you've defined is inverted when this menu item is chosen by the mouse pointer. HIGHBOX In this mode,the box is framed whin its chosen. The two previous bits determine the mode of the chosen menu item. The following combinations are possible: HIGHIMAGE If both bits are cleared,choosing the bit causes a self-defined drawing to be output. HIGHNONE When both bits are set,there isn't any reaction to choosing this item. CHECKED This bit can be set by either the program or Intuition.It lets you know if the menu text has a check next to it or not.You can use this to find out if the item was checked by testing but eight.If its set,the item was checked.You can also use it to cause the item to be checked. You're choosing the mode CHECKIT,ITEMTEXT,COMMSEQ,MENUTOGGLE,ITEM- ENABLED and HIGHBOX for the example: dc.w $10011111 ;mode flag Lets get back to the structure of the menu items.After the flag word,there is a long word whose flag bits determine whether this menu point can be turn off another one.Set this to zero: dc.l 0 ;no connection Now comes the pointer to the structure of the text that should be displayed.If the ITEMTEXT bit isn't set,this pointer must point to the structure of the drawing.If nothing should be shown,you can set this to zero.Use a text in the example and write the following: dc.l menu01text ;pointer to menu text structure The following long word only has a meaning if the HIGHIMAGE flag is set.Then this long word points to the text or the drawing that should be displayed when the menu items box is clicked.Otherwise the long word is ignored,so insert a zero: dc.l 0 ;no drawing when clicked The next entry is a byte that is used for input of keyboard characters,which together with the right key can be used to choose the menu item.This only works if the COMMSEQ bit is set. Place a character here: dc.b 'A' ;choose item using /'A' Since the next item is a long word,you need an "align"peudo-op here.Next comes the long word that points to the menu item structure or a submenu.The submenu is automatically shown when this menu item is clicked.You can't nest them any deeper,however, so this long word is ignored for submenus. If you don't want a submenu to this item,put a zero here: align dc.l 0 ;no submenu The next and final long word is written to by Intuition if you choose several menu itens.In this case,the menu number of the next menu item chosen goes here: dc.l 0 ;preparation Thats the structure for a menu item.You still need the text structure for the text of the item.This isn't complicated,but it makes you get into fine details about the form of the menu.You've already learned about this text structure when you looked at requesters,so we'll skip an explanation. Heres the complete structure of an example menu.You can use two menus,each with two subpoints.The second menu point of the left menu has a submenu with two entries.You ought to type this program in,so that you can experiment with it.You can also use this example to evaluate the clicked menu item. ;**Complete menu structure foe example menu ** menu: dc.l menu1 ;no next menu dc.w 10,30 ;X/Y dc.w 50,10 ;width/height dc.w 1 ;menu enabled dc.l menuname ;menu title dc.l menuitem01 ;menu entry menuname: dc.b "Menu 1",0 ;first menu name align menu1: dc.l 0 ;no further menu dc.w 80,0 ;see above dc.w 50,10 dc.w 1 dc.l menuname1 dc.l menuitem11 dc.w 0,0,0,0 menuname1: dc.b "Menu 2",0 ;second menu name align menuitem01: ;first menu item dc.l menuitem02 ;pointer to next entry dc.w 0,0 ;X/Y dc.w 130,12 ;width/height dc.w $9f ;flags dc.l 0 ;exclude dc.l text01 ;pointer to text structure dc.l 0 ;select fill dc.b "1" ;command align dc.l 0 ;subitem:none dc.w 0 ;next select:no text01: dc.b 0,1 ;colours dc.b 0 ;mode:overwrite align dc.w 5,3 ;X/Y position dc.l 0 ;standard character set dc.l text01txt ;pointer to text dc.l 0 ;no more text text01txt: dc.b "Point 0.1",0 align menuitem02: ;second menu item dc.l 0 dc.w 0,10 dc.w 130,12 dc.w $57 dc.l 0 dc.l text02 dc.l 0 dc.b "2" ;activate with /'2' align dc.l 0 dc.w 0 text02: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l text02txt dc.l 0 text02txt: dc.b "Point 0.2",0 align menuitem11: ;first menu point of the second menu dc.l menuitem12 ;pointer to second menu point dc.w 0,0 dc.w 90,12 dc.w $52 dc.l 0 dc.l text11 dc.l 0 dc.b 0 align dc.l 0 dc.w 0 text11: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l text11txt dc.l 0 text11txt: dc.b "Point 1.1",0 align menuitem12: ;second menu item of second menu dc.l 0 ;no more items dc.w 0,10 dc.w 90,12 dc.w $92 dc.l 0 dc.l text12 dc.l 0 dc.b 0 align dc.l submenu0 ;pointer to submenu dc.w 0 text12: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l text12txt dc.l 0 text12txt: dc.b "Point 1.2",0 align submenu0: ;first point of submenu dc.l submenu1 ;pointer to next point dc.w 80,5 dc.w 90,12 dc.w $52 dc.l 0 dc.l texts0 dc.l 0 dc.b 0 align dc.l 0 dc.w 0 texts0: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0,texts0txt,0 texts0txt: dc.b "S Point 1",0 align submenu1: ;submenu,second item dc.l 0 dc.w 80,15 dc.w 90,12 dc.w $52 dc.l 0 dc.l texts1 dc.l 0 dc.b 0 align dc.l 0 dc.w 0 texts1: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l texts1txt dc.l 0 texts1txt: dc.b "S Point 2",0 align The menu items in this example have the following properties as a result of their flags: Menu 1; The first item,"Point 0.1",can be chosen using the right key and the "1" key.This point alternates between checked and not checked,which can easily be used to check out the key function.If the item is checked and you hit both keys,the check disappears and vice versa.The box at this point is framed when the mouse pointer clicks on it. The second item,"Point 0.2",can be chosen using the right key and the "2"key.This item is checked the first time it is chosen.However,in contrast to the item above,it can't be erased. The box of this item is inverted when clicked. Menu 2; These two points can't be chosen using keys.The box of the upper item is inverted when clicked on:the lower one is framed.When you click the second item,"Point 1.2",a submenu with two entries is displayed. Experiment with this structure a little bit.Change some values and see what happens.As you can see,menu programming isn't as bad as you thought,and it offers a lot of options (but you'll have to do lots of typing!). When you've done experimenting,you'll want to produce your own program with menus.How does the program find whether a menu item in a menu has been clicked on? You already looked at one way to find out the menus state.You can test the CHECKED bit in the flag word of a menu item.If this is set,the user clicked on this item with the mouse. This only works if checking is allowed for the item being tested. You could allow all the menu items to be checked,but this still isn't a good solution--it requires testing all the flag bits of all the menus one after the other.That makes very boring programming. You've already learned about finding about events from Intuition. You've moved the message about which event took place into D6,and you can look at it to find out what happend. If you set the eight bit,the MENUPICK bit,of the IDCMP flag long word in the window definition,the choice of the menu point is reported.Put the following lines in your loop in the main program. loop: move.l execbase,a6 ;exec base address in A6 move.l windowhd,a0 ;window structure pointer move.l 86(a0),a0 ;user point pointer in A0 jsr getmsg(a6) ;get message tst,l d0 ;whay happend? beq loop ;nothing happend move.l d0,a0 ;message pointer in A0 move.l $14(a0),d6 ;event in D6 If the program makes it out of the loop,an event as taken place. You have the events flag in the D6 register.You can evaluate the event using CMP or BTST to find out which flag bits are set.You can then execute the function corresponding to the set bit.You can use lines like the following ones: cmp #$200,d6 ;WINDOWCLOSE? beq ende ;yes:program end These lines terminate the program when the window is closed. If the user chose a menu item,there is a $100 in the D6 register. You now need to determine which item it was. You can find this information in a word that comes right after the long word with the event flags in the message structure.Write: move $18(a0),d7 You now have the code for the clicked menu item in the D7 register.If the user just pressed the right key and let it go without choosing a menu item,you'll find a $FFFF here.This word doesn't contain just one,but three pieces of information: Which menu was the item chosen from? Which menu item? Which submenu? The information is divided in three bit groups.The division is as follows: Bits 0-4 Menu title number Bits 5-10 Menu item number Bits 11-15 Submenu item number The numbering begins with zero-ie the first menu point of the first menu has the numbers 0 and 0. To try this out insert the following lines: move d7,d6 ;move code into D6 lsr #8,d7 ;shift right 11 times lsr #3,d7 ;submenu item now in D7 clr.l d5 roxr #1,d6 ;bit 0 in X-flag roxl #1,d5 ;menu number now in D5 and.l #$7f,d6 ;issolate lower bits cmp #$7f,d6 ;no menu item? beq loop ;no:continue lsr #4,d6 ;else menu item in D6 ende By making a test run with AssemPro,you can easily see if this works right-just look at the registers after the program is over. If you,for example,want to write a program with four menus with 10 menu items each,this sort of method is too much work-there are 44 tables.For this reason,lets look at a short program that takes care of the necessary structure table itself. The menu structure is built very simply-it doesn't offer submenus or the option of choosing items via the keyboard.If you want these extras,you can still use this program,but you'll have to use MOVE commands to insert the desired flags and pointers. The input that this program needs is a list of the menu names and the items in each menu.The addresses of the menu texts go in a table with the following simple form: dc.l Menu title 1 dc.l Point1,Point2,Point3,...,0 dc.l Menu title 2 dc.l Point1,Point2,Point3,...,0 dc.l Menu title 3 oder 0 This program is set up in such a way that up to four menus can lie next to each other (in normal screen resolution),which is often plenty.The table above ends by putting a zero instead of a pointer to the nxt menu title.As you can see,its pretty simple. This program is inserted in your big program right behind the "setmenu"label.After the "bsr setmenu"command is executed,the menu structure is built and initialized at the same time.You don't need to change the rest of the program,it'll be shorter that way. Heres the program fragment for the complete "setmenu"routine: setmenu: ;*initialize menu structure lea mentab,a0 ;pointer to text pointer in A0 lea menu,a1 ;pointer to menu field in A1 move #10,d1 ;horizontal menu position=10 menuloop: clr.l d2 ;vertical menu position=0 move.l a1,a2 ;save address of pointer tst.l (a0) ;another menu there? beq setmenu1 ;no:quit clr.l (a1)+ ;"no more menus"preperations move d1,(a1)+ ;set X-position add.l #70,d1 ;and increment move.l #50,(a1)+ ;Y-position and width move.l #$a0001,(a1)+ ;height and flag move.l (a0)+,(a1)+ ;menu title lea 12(a1),a3 move.l a3,(a1)+ ;pointer to menu item clr.l (a1)+ ;reserved words clr.l (a1)+ itemloop: tst.l (a0) ;last entry? beq menuend ;yes:menu done lea 54(a1),a3 move.l a3,(a1)+ ;pointer to next item move.l d2,(a1)+ ;X- and Y-positions add #10,d2 ;Y-position+10 move.l #$5a000a,(A1)+ ;WIDTH/HEIGHT move #$52,(a1)+ ;flag:normal clr.l (a1)+ ;no connection lea 16(a1),a3 move.l a3,(a1)+ ;text structure pointer clr.l (a1)+ ;no fill structure clr.l (a1)+ ;no command,no submenu clr.l (a1)+ ;and no continuation move #$1,(a1)+ ;set text structure:colour clr.l (a1)+ ;mode 0 move.l #$50003,(a1)+ ;X- and Y-position clr.l (a1)+ ;standard character set move.l (a0)+,(a1)+ ;text pointer clr.l (a1)+ ;no continuation bra itemloop ;next item... menuend: ;eventual transfer to next menu clr.l -54(a1) ;erase pointer to next item tst.l (a0)+ ;increment table pointer tst.l (a0) ;another menu there? beq setmenu1 ;no:done move.l a1,(a2) ;pointer to next menu bra menuloop ;and continue setmenu1: ;*initialize menu (like before) move.l intbase,a6 ;intuition base address in A6 move,l windowhd,a0 ;window structure in A0 lea menu,a1 ;pointer to menu structure jsr setmenustrip(a6) rts You need three things yet for this program:the memory to be used for the structure,the table of text pointers and the text.Heres an example: mentab: dc.l menu1 ;first menu title dc.l mp11,mp12,mp13 ;menu items dc.l 0 ;end of menu 1 dc.l menu2 ;second menu title dc.l mp21,mp22,mp23 ;menu items dc.l 0 ;end of menu 2 dc,l 0 ;you're out of menus! ;** Menu Text ** menu1: dc.b "Menu 1",0 mp11: dc.b "Point11",0 mp12: dc.b "Point12",0 mp13: dc.b "Point13",0 menu2: dc.b "Menu 2",0 mp21: dc.b "Point21",0 mp22: dc.b "Point22",0 mp23: dc.b "Point23",0 align ;** Storage space for menu structure ** menu: blk.w 500 Make sure that the memory area reserved for the menu structure is big enough and change the entry "blk.w 500"to the calculated value. If you use this program,and want to build some special features into the menu (for instance key commands),you can make entries in the menu structure table while the program is running.You can find the word (or byte or long word) that interests you in the table as follows: For example,to find the keyboard command byte of the second entry in the first menu,calculate as follows: Address = Start_address+Menu*30+(entry-1)*54+26 which in the example comes to: Address = menu+30+54+26 = menu+110 The 26 is the distance from the beginning of the MenuItem structure to the desired byte,the command byte.In this way,you can calculate the addresses and use MOVE commands to modify the menu to fit your wishes.By the way,in the example above,the correspond- ing flag bit must be set as well,so that the keyboard command is recognized. Now lets get back to the window.Its nice to have a window that you can change and close,but you really want to be able to output text in a window! 7.6.Text Output. ---------------- Its very easy to use Intuition's text output function.Use the PrintIText function (offset -216).It needs four parameters. In A0 A pointer to the RastPort of the window.You can find this in the window structure. In A1 A pointer to the text structure of the text that should be output. In D0 The X-position. In D1 The Y-position of the text in the window. Its very easy to enter the X- and Y-positions.You've already used the text structure twice (for requesters and menus). Whats new is accessing the windows RastPort.The RastPort is a structure that describes the window.The address is needed by several Intuition functions. The pointer to the RastPort starts at the 50th byte in the window structure.You can access it as follows: move.l windowhd,a0 ;address of window structure move.l 50(a0),a0 ;RastPort address in A0 Now you've got the address of the RastPort.Lets write a routine that prints a text.The X- and Y-positions are in D0 and D1 respectively and the address of the text structure in A1 before the routine is called: PrintIText = -216 ... print: move.l intbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;address of window structure move.l 50(a0),a0 ;rastport address in A0 jsr printitext(a6) ;call function rts You can try out this routine by using the requesters text that is still in a structure of the program.Write the following lines before the "loop"label: lea btext,a1 ;pointer to text structure in A1 move.l #10,d0 ;X-position move.l #30,d1 ;Y-position of text bsr print ;output text Start the program and the text appears in the middle of the window If this doesn't happen,check the colour of the text in the text structure.Its probably zero.Just change it to three,and the text appears in red the next time you start the program. 7.7.Images. ----------- An image is a drawing that goes in a rectangular field and is defined bitwise.The disk symbol of the Intuition screen and the system gadgets in the screen and window borders are examples of such Images. The rectangle that the drawing goes in can be arbitrarily large, but each pixel in the rectangle needs its own bit,so programming screen-sized Images isn't advisable.You'll stick to an Image that requires about 32x16 bits-an Image thats about 3x1cm. You can make all sorts of images as you've seen looking at window gadgets.There is an Intuition functionthat draws an Image:It is the DrawImage function (offset -114) and it needs 4 parameters: In A0 The address of the rastport image is drawn in.You've already learned how to access this address in the section on the text function. In A1 The structure address of the image to be drawn. In D0 The relative X-position In D1 The relative Y-position of the drawing. Lets draw this picture in your window.It justs takes a simple routine.You just need to put the address of the image structure in A1 and the position of the image in D0 and D1 before you call it. DrawImage =-114 ... draw: ;*draw image move.l intbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;pointer to window structure move.l 50(a0),a0 ;now,rastport address in A0 jsr drawimage(a6) ;draw image rts Now you need the structure of the image.The structure contains nine entries which have the following meanings: The first two entries are words which specify the distance in the X- and Y-direction from the co-ordinates that were given to tell where the image should be drawn.You'll just put two zeros here: image: dc.w 0,0 ;X- and Y-position Next come two words which specify the width and height of the image in pixels.Lets draw a 32x13 point image.Enter: dc.w 32,13 ;width and height of image The next word in the list specifies the number of planes in the drawing.If its a simple image that only uses two colours,just enter a one.For more colours,you'll need a correspondingly bigger number.When more colurs are worked with,the bit pattern of the image must have more data.Lets just have one bit plane: dc.w 1 ;one bitplane:2^1=2 colours Next comes a long word that points to the data of the image: dc.l imgdata ;pointer to image data The next two bytes are very interesting.The first byte,the PlanePick byte,tells which plane of the window or screen the image data should be written in.Since you only have one plane,you need to enter the bit plane of the window.This information is found in the bits of the byte-bit0 stands for plane 0,bit 1 for plane 1,etc ..You also define the colour of the image with this input.If you enter a two,every set bit of your image represents a red point. dc.b 2 ;drawing red:plane 1 The second byte,the PlaneOnOff byte,is an interesting enhancement. Each bit of the window bit plane corresponds to a whole number here.The only bytes that are interesting though are the ones that are cleared in the PlanePick byte.If the bit is set in PlaneOnOff, evert bit of the image in the corresponding plane is set.Otherwise they are cleared.To make sure that each bit of the image that isn't set appears white,enter a one.All the bits of the image that aren't set,are set in Plane 1 and appear white. dc.b 1 ;background:white The last entry of the structure is a lobg word that points to another image.You don't need this,so set the long word to zero: dc.l 0 ;no more images Heres a quick overview of the image structure: image: dc.w 0,0 ;X- and Y-positions dc.w 32,13 ;width and height of image dc.w 1 ;one bitplane:2^1=2 colours dc.l imgdata ;pointer to image data dc.b 2 ;drawing red:plane 1 dc.b 1 ;background:white dc.l 0 ;no more images Now lets produce the image data.Each image row uses a word,long word,or several of these represent the pattern.The set points of the image correspond to the set bits.This is repeated as often as the height of the image requires.The data on each line must begin on a word border,on a even address. For the example,its easy to decide on the data,since you're going 32 points across-that corresponds to exacty one long word.Its easiest to program the image using the binary representation of the data. Lets use,as an example,an image that represents a switch in "OFF" mode.This form is chosen for a good reason,so you should type it in.In the chapter on gadgets thats coming up,we'll show you how to turn the switch on.Here is the example data for the switch image: imgdata: ;Data for switch in "OFF" mode dc.l %00000000000000000000000000000000 dc.l %00000000000000000000111000000000 dc.l %00011101110111000001111100000000 dc.l %00010101000100000001111100000000 dc.l %00010101100110000001111000000000 dc.l %00011101000100000011100000000000 dc.l %00000000000000000111000000000000 dc.l %00000000000000001110000000000000 dc.l %00000000000111111111100000000000 dc.l %00000000001111111111110000000000 dc.l %00000000001111111111110000000000 dc.l %00000000000110000001100000000000 dc.l %00000000000000000000000000000000 Once you've typed in this data,you can experiment with displaying it on the screen.Enter the following lines before the "loop"label: move.l image,a1 ;pointer to image structure move #30,d0 ;X-postion in window move #50,d1 ;Y-position bsr draw ;draw image How do you like the image on the screen?You'll run into this switch again when we talk about putting the switch in the "ON" state when discussing gadgets.You need to look at other methods of drawing in the window first,though. 7.8.Borders. ------------ A border is a collection of lines that are connected.They can be of any length or at any angle.Intuition lets you draw borders to do things like put frames around windows and screens.They are used to put borders around pictures or text,especially for use with string gadgets.We'll talk about that later,though. Its easy to draw borders.Just use the Intuition function DrawBorder (offset -108) which needs four parameters: In A0 The rastport address of the output medium the lines should be drawn in.Use your window. In A1 The address of the border structure.We'll look at the form of this structure shortly. In D0 The relative X-co-ordinate which is used with the X- and Y co-ordinate list to calulate the actual line co-ordinates. In D1 The relative Y-co-ordinates.Relative,here too,means that this is relative to the upper left corner of the screen. Lets write a short routine that is called with three parameters. The structure address in A1 and the X and Y co-ordinates are in D0 and D1 respectively when the routine is called.The border is drawn in the window whose structure address is in "windowhd". DrawBorder =-108 ... borderdraw: ;* draw several lines move.l inbase,a6 ;intuition base address in A6 move.l windowhd,a0 ;pointer to window structure move.l 50(a0),a0 ;now rastport address in A0 jsr drawborder(a6) ;draw lines rts Now lets look at the border structure.The list needs the eight following parameters: First,you need two words for the vertical and horizontal distance from the co-ordinates given in the function call.To avoid losing sight of some of the many distance entries,put two zeros here: border: dc.w 0 ;horizontal distance dc.w 0 ;vertical distance Next come two bytes that determine the colour.Use a red frame: dc.b 3 ;red frame dc.b 0 ;background (unused) As you can see,the background colour isn't used.You have two modes to choose between for drawing the lines.The following mode determines the mode that is used.If it is zero,each line is drawn in the colour chosen,no matter what was done before.This is the JAM1 mode.The other mode is the XOR mode which ignores both colour entries.In this mode,all the points that lie under the line have their colour value inverted.As a result,a white point becomes black,and a blue one becomes red.That is mode two.Lets use the JAM1 mode for the example: dc.b 0 ;mode:JAM1 (2=XOR) The next entry specifies how many co-ordinate pairs there are in the list.Since this word must be on an even address,you need to use the "align"peudo-op first.Then enter the number of pairs. Remember that you need three points to draw two lines:beginning, corner and end point.To draw a rectangular frame,you need five pairs: dc.b 5 ;5 X,Y pairs used together The next item is a pointer to the co-ordinate table that contains a list of points to be connected: dc.l coord ;pointer to cordinate table The border structures final entry is a long word that can point to another border structure.If you don't have any more structures to be pointed to,just enter a zero here.The pointer is useful for connecting two independant border structures-for example,to produce a two coloured frame that really stands out.You don't need this pointer in the example,though: dc.l 0 ;no more structures Thats the border structure.Now lets look at the co-ordinate list. For the example,it consists of five pairs of numbers which represent a rectangle.I recommend entering these values,because you'll use them in example programs further down the line. coord: ;coordinates for rectangle frame dc.w -2,-2 dc.w 80,-2 dc.w 80,9 dc.w -2,9 dc.w -2,-2 Heres a quick overview of the border structure: border: dc.w 0 ;horizontal distance dc.w 0 ;vertical distance dc.b 3 ;red frame dc.b 0 ;background (unused) dc.b 0 ;mode:JAM1 (2=XOR) dc.b 5 ;5 X,Y pairs used together dc.l coord ;pointer to cordinate table dc.l 0 ;no more structures coord: ;coordinates for rectangle frame dc.w -2,-2 dc.w 80,-2 dc.w 80,9 dc.w -2,9 dc.w -2,-2 Once you've typed this in,you can try the whole thing out.Type the following lines before the "loop"label in the program: lea border,a1 ;address of the border structure move #20,d0 ;X base position move #80,d1 ;Y base position bsr drawborder ;draw frame As you can see,using enough X and Y co-ordinates,you can draw the Eiffel tower.Thats enough about simple drawings.You want to put some life into your drawings and text.Lets manipulate them with the mouse! 7.9.Gadgets. ------------ We already talked a bit about gadgets when you looked at screen construction.Looking at system gadgets like the window close symbol,you can activate by clicking and causes a program function to be executed. You can make your own gadgets as well.Intuition allows you a lot of interesting possibilities. There are four types of gadgets: Boolean gadgets are used in Yes/No situations.You can click and activate it (Yes) or deactivate it (No). String gadgets are used to accept input of text of a specified length. Integer gadgets are a special sort of string gadgets which accept the input of a decimal number.Intuition converts the value into a long word and sends it to the program. Proportional gadgets let you choose an analog value with the mouse You can move these around with the mouse. 7.9.1.Boolean Gadgets. ---------------------- Lets start with the simplest type,the boolean gadget.an example of this sort of gadget is the close symbol of the window.The only status it differenciates between are clicked and not clicked.Lets develop a gadget of this type step by step.The flags and other parameters are similar for the other gadgets. Each gadget needs a structure containing fifteen entries.There is a pointer to this structure in window,screen or requester that the gadget is to appear in.Theres always a long word available for this purpose.Up to this point,you've just put a zero there.If there is an address of a gadget structure there,the gadget or gadgets are displayed when the window is opened. A gadget structure as the following entries: The first long word is a pointer to the next gadget to be installed.The gadgets are displayed in a row,like pearls on a string.This pointer is the first gadget in this linked list of gadgets.If you just want one gadget in your window,put a zero here: gadget1: dc.l 0 ;no more gadgets The next two words determine the position of the gadget in the window.There are several ways to determine the position.Use flags to access the various possibilities.Lets start with a gadget that stays in one spot: dc.w 40 ;X and dc.w 50 ;Y position of the gadget The next two words determine the size of the gadgets Hit box.This box isn't the visible size of the gadget (that depends on the image data).It is the size of the rectangle that Intuition should watch.If the mouse pointer is moved into this box and the left button pressed,the gadget is activated.Clicking on parts of the gadget that are outside this box have no effect! dc.w 32 ;width and dc.w 13 ;height of the hit box Next comes the word whose bits determine the properties of the gadget.Bits 0 and 1 determine what should happen when this objects hit box is clicked on.The meanings of the various values of these bits go as follows: Bit 0 1 Value Name Meaning ------------------------------------------------------------------ 0 0 0 GADGHCOMP The gadget inverted 0 1 1 GADGHBOX The gadget framed 1 0 2 GADGHIMAGE Another image appears 1 1 3 GADGHNONE No reaction Bit 2 determines whether the gadget should consist of a drawing or a border.If it is set(Value+4),it is treated as an image;otherwise its treated like a border. The next bit determines if the gadget should appear in the upper or lower border of the frame.If it is set(Value+8).the position is relative to the lower border;otherwise it is relative to the upper border.The next bit as the same meaning for the horizontal position.If set(Value+$10),it is a relative positioning.Otherwise, it is an absolute positioning. Notice that when you define a gadget to be relative,you must have a negative value in the position input in the first word of the structure.Since the desired position isn't under,but its over this position! In this way,you can choose either absolute or relative positioning of the gadget.An example of a gadget that is positioned absolutely is the system gadget,close window.An example of a relative gadget is the symbol for changing the size. The width and height of the gadgets hit box can also be relative to the window size.Specify this by using bit 5 for width (Value + $20)and bit 6 for the height (Value +$40).A set bit mens a relative size. Bit 7 (Value+$80)makes the object active as soon as the window is opened. Bit 8 (Value+$100)determines whether the gadget can be used or not If this bit is set,the gadget can't be activated. For the example,you'll use absolute positioning and size,the inverted appearance for the activated gadget,and the representation of the object as an image.That means you must use the value four: dc.w 4 ;flags:image,invert Next comes a word whose bits are used as flags.This flag is called the Activation Flag.It determines the functions of the gadget.The bits,their values and meanings follow: Bit Value Name Meaning ------------------------------------------------------------------ 0 1 RELVERIFY Causes the gadget to be activated only when the left mouse key is let loose over the gadget. 1 2 GADGIMMEDIATE Lets the gadget be active as soon as there is a click. 2 4 ENDGADGET Lets you choose to end this choice and have it disappear if this is a requester gadget. 3 8 FOLLOWMOUSE Lets the gadget know the mouse position at regular intervals from the time it is selected until the time it is deselected.You can use this to move the gadget with the mouse when you want to change the gadget position. 4 $10 RIGHTBORDER This makes sure thay when borders are used that the page is adjusted to the size of the gadget so that it fits in the border. 5 $20 LEFTBORDER 6 $40 TOPBORDER 7 $80 BOTTOMBORDER 8 $100 TOGGLESELECT Allows the objects state to change every time it is clicked.If activated,it becomes deactivated and vice versa. 9 $200 STRINGCENTRE For a string gadget,these two bits determine whether the string should appear centred or right justified.If neither is set,the string is output left justified. 10 $400 STRINGRIGHT 11 $800 LONGINT Turns a string gadget into a Integer gadget (explanation later). 12 $1000 ALTKEYMAP Causes another ketboard placement to be in effect for string gadget input Thats it for the activation flags.Lets choose the TOGGLESELECT and GADGETIMMEDIATED flags for example: dc.w $102 ;activation The next word of the gadget structure determines the gadget type. Heres the meaning of the individual bits: Bit Value Name Meaning(report what circumstances) ---------------------------------------------------------------- 0 1 BOOLGADGET This is a boolean gadget 1 2 GADGET002 2 4 STRGADGET String order Integer gadget 0+1 3 PROPGADGET Proportional gadget System gadgets: 4 $10 SIZING Size changing gadget 5 $20 WDRAGGING Moving gadget for window 4+5 $30 SDRAGGING Same for screen 6 $40 WUPFRONT Gadget to move window forward 6+4 $50 SUPFRONT Gadget to move screen forward 6+5 $60 WDOWNBACK Move window back 6+5+4 $70 SDOWNBACK Move screen back 7 $80 CLOSE Window close gadget Type definitions: 12 $1000 REQGADGET Requester gadget 13 $2000 GZZGADGET Border gadget in GIMMEZEROZERO window 14 $4000 SCRGADGET Screen gadget when set 15 $8000 SYSGADGET System gadget when set You want to use a simple boolean gadget for your example,so enter: dc.w 1 ;gadget type:boolean Next comes a pointer to the gadget structure.The first pointer contains the address of the image or border structure which should be used to represent the gadget.If no representation is needed,put a zero here.You want to represent the gadget as an image,so put a pointer to the image structure that you produced in the chapter about images: dc.l image ;gadget image The next pointer is only used if the GADGHIMAGE flag in the flag word of the structure is set.This is a pointer to another structure that should be put on the screen when the object is activated.If a border structure is used for the gadget represent- ation,this must be a border structure as well.You won't use a second image,so put a zero here: dc.l 0 ;no new gadget displayed The next pointer is to the text structure that should be output by the gadget.If no text is needed,just put a zero here.You want to use some text,however: dc.l ggtext ;gadget text Now comes a long word that determines which gadgets are deactivated when this is activated.This function still doesn't work right so put a zero here: dc.l 0 ;no exclude You'll set the next pointer to zero as well,because it is only used for String and Proportional gadgets.For these gadgets,this is a special structure to describe the characteristics of the gadget. Its called SpecialInfo. dc.l 0 ;no SpecialInfo The next word contains the Gadget Identification (ID) number: dc.w 1 ;gadget ID Finally there is a long word that doesn't have any function,so put a zero here: dc.l 0 ;user data (ignore) Thats it.Heres a quick overview of the gadget structure: gadget1: dc.l 0 ;no more gadgets dc.w 40 ;X and dc.w 50 ;Y position of gadget dc.w 32 ;width and dc.w 13 ;height of hit box dc.w 4 ;flags:image,invert dc.w $102 ;activation flags dc.w 1 ;gadget type:boolean dc.l image ;gadget image dc.l 0 ;no new gadget displayed dc.l ggtext ;gadget text dc.l 0 ;no exclude dc.l 0 ;no SpecialInfo dc.w 1 ;gadget ID dc.l 0 ;user data (ignore) You've already prepared a structure that you can use for this image.Now you need the text that appears under the gadget. Since the gadget looks like a switch,label it "switch".The text structure looks like this: ggtext: dc.b 1,0 ;colours dc.b 1 ;mode align dc.w -8,14 ;X and Y position dc.l 0 ;standard font dc.l swtext ;pointer to text dc.l 0 ;no more text swtext: dc.b "switch",0 align Once you've typed this in,save it,assemble it and start again.You can click the switch and cause it to be inverted.Click it again, and it appears normal. Now you can experriment with the structure.If you change the flag from four to five,you can cause the gadget to be framed when it is activated.Set the RELVERIFY bit(bit0:+1)in the Activation Flag word.Then you can move the mouse pointer onto the object and press the button.It is activated.Keep the mouse button pressed down and move the mouse.Once you leave the hit box,the activation disapears This way,you can avoid accidently activating a gadget. Now you want to display the switch in an on state.This is easy.All you need to do is produce another image structure,one for the on state.You put this pointer in the long word right after the pointer to the normal image structure.You can change the flag word to six which causes a second image to be displayed when the gadget is activated. Here is the image structure for the switch in the one state. image2: dc.w 0,0 ;no offset dc.w 32,13 ;32x13 pixels dc.w 1 ;mode 1 dc.l imgdata2 ;pointer to the data dc.b 2,1 ;same colours as before dc.l 0 ;nothing else imgdata2: ;data for switch in the On state dc.l %00000000000000000000000000000000 dc.l %00000000011100000000000000000000 dc.l %00000000111110000011101001000000 dc.l %00000000111110000010101101000000 dc.l %00000000011110000010101011000000 dc.l %00000000000111000011101001000000 dc.l %00000000000011100000000000000000 dc.l %00000000000001110000000000000000 dc.l %00000000000111111111100000000000 dc.l %00000000001111111111110000000000 dc.l %00000000001111111111110000000000 dc.l %00000000000110000001100000000000 dc.l %00000000000000000000000000000000 Now the state of the object can be determined by looking at the picture.If the gadget is activated,the switch is on.If not,the switch is off. Thats it for boolean gadgets.You can learn about the things you did'nt touch with some experimentation.You want to get to the string gadgets that also do some interesting things. 7.9.2.String Gadgets. --------------------- Lets pretend you want a program to load data from the disk.To get the user to enter the filename,you need to output text telling the user to enter the name.Then you need to call an input routine to evaluate the keyboard input. Its easier and more elegant to use a String gadget.This function allows for easy input and/or editingof short text.You have the option of having the text framed.The Undo function can be used by pressing the right key and a "Q",and the old contents of the gadget,the old text are restored. You can also vary the size of the text and the input field.If the text is longer than the input field is wide,the text is moved back and forth through the visible area when you move the cursor keys or the normal input to the border. You can also restrict input to just digits.This makes it posible to accept numeric input.Intuition even converts the digit string into a binary number.This saves the machine language programmer some work.A specialized String gadget of this sort is called a Integer gadget. The structure is similar to the Boolean gadgets structure.There are only two major differences: The type word of the structure must be a four to declare that this is a String gadget (STRGADGET). The pointer to the SpecialInfo structure is needed.Put a pointer to the StringInfo structure that you are going to design later here. The width and height entries in the gadget structure have a different meaning than they had previously.They do declare the area in which you can bring the mouse pointer to activate the String gadget.However,it is also used for representation of text. These values determine the size of the box in which the text is output.You should surround the box with a border using the Border function,so that the user can see where it is. If the text is longer than the box,only a portion of it is seen on the screen.You can move through the area by entering text or using the left/right cursor keys to move through the box.The characters that are entered are inserted at the cursor position,so the rest of the text is shifted by one character when you are on the right edge of the input area.The following functions can be used for editing this text: Cursor key left/right Moves the cursor over the text thats already on hand.Moves the text through the Container. Cursor keys with Puts the cursor on the beginning or the end of the text. Deletes the character under the cursor. Deletes the character to the left of the cursor. Ends text input. right+"Q" This is the Undo function.It replaces the text with the original contents. The StringInfo structure only has a few entries: First theres a pointer to the memory area that is used to store the text that is input.The memory buffer must be big enough to handle all the text entered. strinfo: dc.l strpuffer ;pointer to text buffer Next comes the pointer to the Undo buffer.This pointer and this buffer are only needed if you want the Undo function.If you do,you must have a buffer that is at least as big as your text buffer. Every time the string gadget function is called,the text buffers contents are copied into this buffer.To get the old contents back, just press the right key and the "Q"key.The contents of the Undo buffer are copied back to the text buffer.If you use several string gadgets in a program,you can use the same Undo buffer for all of them,since only one string gadget is used at one time. dc.l undo ;pointer to undo buffer The following word contains the cursor position in the text.You should set this word to zero,so that the user can see the beginning of the text when the string gadget appears. dc.w 0 ;cursor position The next word contains the maximum number of characters that can be input.If you type one more than this number of characters,the screen blinks,to show that you can't enter a longer input string. The number of characters and the reserved space for the input field don't have to agree,since text can be scrolled by typing. dc.w 10 ;maximum # of characters The following word tells at which character of text in the buffer, the output to the box should begin.You should put a zero here,so that the user can see the beginning of the text. dc.w 0 ;output text from this character The next five words are used by Intuition,so you don't have to initialize them.Just put zeros here.The words contain the following information: dc.w 0 ;character position in undo buffer dc.w 0 ;number of chars in text buffer dc.w 0 ;number of chars visible in box dc.w 0 ;horizontal box offset dc.w 0 ;vertical box offset The next two long words are initialized by Intuition as well: dc.l 0 ;pointer to rastport dc.l 0 ;long word with value of the input ; ;(for integer gadgets) The final entry is a pointer to the keyboard table that is used if the ALTKEYMAP flag of the gadget is set. dc.l 0 ;standard keyboard table Heres a quick overview of the StringInfo structure: strinfo: dc.l strpuffer ;pointer to text buffer dc.l undo ;pointer to undo buffer dc.w 0 ;cursor position dc.w 10 ;maximum # of characters dc.w 0 ;output text from this character dc.w 0 ;character position in undo buffer dc.w 0 ;number of chars in text buffer dc.w 0 ;number of chars visible in box dc.w 0 ;horizontal box offset dc.w 0 ;vertical box offset dc.l 0 ;pointer to rastport dc.l 0 ;long word with value of input ; ;(for integer gadgets) dc.l 0 ;standard keyboard table Here are the text and undo buffers: strpuffer: dc.b "Hello!",0,0,0 undo: dc.l 0,0,0,0 align Once you've entered these lines,you can either alter the old gadget structure or build a new one.We'd recommend building another gadget structure so that you can have the switch and use it later.Change the first pointer in the old structure from zero to "gadget1"and insert this new structure.Here is an example strucure for the string gadget.It as the following entries: gadget1: ;*structure for string gadget dc.l 0 ;no more gadgets dc.w 20,80 ;position dc.w 80,10 ;width and height of box dc.w 0 ;flags:normal dc.w 2 ;activation($802 for long int) dc.w 4 ;type:string gadget dc.l border ;pointer to border dc.l 0 ;no drawing selected dc.l 0 ;no text dc.l 0 ;no exclude dc.l strinfo ;pointer to stringinfo structure dc.w 2 ;gadget ID dc.l 0 ;no user data border: ;*border for box frame dc.w 0,0 ;no offset dc.b 3,3 ;red colour dc.b 0 ;mode:JAM1 dc.b 5 ;5 X,Y pairs dc.l coord ;pointer to coordinates table dc.l 0 ;no more structures coord: ;*coordinates for frame dc.w -2,-2 ;start in upper left corner dc.w 80,-2 ;upper right dc.w 80,9 ;lower right dc.w -2,9 ;lower left dc.w -2,-2 ;back to beginning This data causes a red rectangle,the border,to appear around the "Hello!"text.You can change the text by clicking in the field and editing once the cursor appears.If you type something wrong,you can use the undo function(the right key and the Q key),to get "Hello!"back. Once you've done some typing and deactivated the gadget by pressing or by clicking outside the field (cursors disapear),you can terminate the program. Change the activation flag to $802 and the "strbuffer"to "dc.l 0,0,0,0",assemble,and then start the program.You can type in the string gadget once it has been activated,but you can only enter digits.The screen blinks if you enter letters. Enter a number,and then end the program after deactivating the gadget.If you look at the stringinfo structure you can look at the value of the number you input(in hex)in the eight long word. After looking at boolean,text and numeric input to gadgets,lets look at Proportional gadgets which allow the user to enter analog values by moving a symbol. 7.9.3.Proportional Gadgets. --------------------------- You've seen the advantages of slider devices over knobs that you turn,maybe on a hifi,maybe on a toaster,but certainly someplace. Its easier to tell the state the item is in with a slider, especially if several such devices are next to each other(for example graphic equalizers).You can represent sliders on the Amigas screen and work with them with the mouse.This offers a nice way to represent information graphically in your programs. You can do this with gadgets.Using Proportional gadgets,you can put a symbol in a frame and move horzontally and/or vertically.The size of the frame and the slider can be variable size,so that the frame size is relative to the screen size so when the window changes size,it will also.The slider can be set up so that its size in the grows or shrinks. These are best seen via example and experimentation.(The posibilities mentioned do not form a complete list by any stretch of the imagination.)You want to set up a simple Proportional gadget that can be moved horizontally. You need a gadget structure that as the same form as others.To show the differences,heres a complete example structure for your gadget.You can connect this gadget to the other one,by changing the first long word in the last structure to "dc.l gadget2". gadget2: ;*structure for Proportional gadget dc.l 0 ;no more gadgets dc.w 150,30 ;position dc.w 100,10 ;width and height of frame dc.w 4 ;flags:GADGIMAGE dc.w 2 ;activation:GADGIMMEDIATE dc.w 3 ;type:proportional gadget dc.l mover ;pointer to slider data dc.l 0 ;no select structure dc.l 0 ;no text dc.l 0 ;no exclude dc.l propinfo ;pointer to propinfo structure dc.w 3 ;gadget ID dc.l 0 ;no user data You see two special features.Use an image structure for the mover and put a pointer to another structure in the spot for the Special Info pointer. First,lets look at the "mover"structure,the sliders image structure.Heres an example of this structure: mover: ;*structure for slider image dc.w 0,0 ;no offset dc.w 16,7 ;16x7 pixels big dc.w 1 ;one bit plane dc.l moverdata ;pointer to image data dc.b 1,0 ;colour:white dc.l 0 ;don't continue moverdata: ;*image data for mover dc.w %0111111111111110 dc.w %0101111111111010 dc.w %0101011111101010 dc.w %0101010110101010 dc.w %0101011111101010 dc.w %0101111111111010 dc.w %0111111111111110 Up till now,there was'nt anything new.Now lets look at the PropInfo structure that describes the properties of the Proportional gadget. The structure starts with a flag word that contains the following bits: Bits Value Name Meaning ----------------------------------------------------------------- 0 1 AUTOKNOB Mover is set up automatically 1 2 FREEHORIZ Allows horizontal movement 2 4 FREEVERT Allows vertical movement 3 8 PROPBORDERLESS Turns off automatic framing 8 $100 KNOBHIT Set when the mover is touched You can set the first four bits to get the representation that you want.Bit 8 is set by Intuition when the mover is clicked with the mouse pointer. Bit 0,AUTOKNOB,allos for the simplest sort of Proportional gadget. If this bit is set,no move data are used for the mover image. Instead,a white mover is generated that is adjusted to the size of the box and the values to be represented.When you use this slider to represent the displayed lines in a long text of a program,the displayed lines are a percentage of the total text.The relationship between the total number of lines and the lines shown is represented by an AUTOKNOB as the relationship between the frame and the slider.The bigger the percentage,the bigger the slider is.You don't want to work with this though,even though it is simple and interesting,because a simple white button isn't particularly attractive.If you experiment with it,make sure that the pointer to the image data points to a four word long buffer that Intuition can use to store values.The buffer is of the following form: buffer: dc.w 0 ;X position of the slider in the box dc.w 0 ;Y position in the box dc.w 0 ;width of slider dc.w 0 ;height of slider Leys look at the PropInfo structure.Since you're not using AUTOKNOB and wish to allow horizontal movement only,put two in as a flag: propinfo: dc.w 2 ;flags:FREEHORIZ In the next two words of the structure,the horizontal (HorizPot) and vertical (VertPot) position of sliders are stored.A value of zero means left or upper,while the value $FFFF means right or lower.The value that results from movement is in this range.You set these values to zero at the start of the program.After moving the mouse,there is different values here. dc.w 0,0 ;X and Y position of the slider Next come two words which determine the size of the AUTOKNOB or the step size of the slider(this determines how far the slider moves when you click in the box next to the slider).These words are called HorizBody (horizontal movement) and VertBody (vertical movement). dc.w $ffff/16 ;horizontal step size:1/16 dc.w 0 ;no vertical movement ;The next six words are initialized by Intuition. dc.w 0 ;box width dc.w 0 ;box height dc.w 0 ;absolute step size horizontal dc.w 0 ;and vertical dc.w 0 ;left border of box dc.w 0 ;upper border of box Thats it.Heres a quick overview of the PropInfo structure: prpoinfo: dc.w 2 ;flags:FREEHORIZ dc.w 0,0 ;X and Y position of slider dc.w $ffff/16 ;horizontal step size:1/16 dc.w 0 ;no vertical movement dc.w 0 ;box width dc.w 0 ;box height dc.w 0 ;absolute step size horizontal dc.w 0 ;and vertical dc.w 0 ;left border of box dc.w 0 ;upper border of box Once you've typed this in,you can start the program and try it out. You can also try vertical movement by setting the flag word equal to six,the vertical step size to $FFFF/10,and the height of the gadget to 80,for the example.To try out the AUTOKNOBs,change the flag value to seven. 7.10.Example Program. --------------------- Here is a complete example program using what you have learned in this chapter: ;7_Intuition.asm ;** Demo-Program for working with Intuition ** movescreen =-162 openscreen =-198 closescreen =-66 openwindow =-204 closewindow =-72 autorequest =-348 setmenustrip =-264 clearmenustrip=-54 printitext =-216 drawimage =-144 drawborder =-108 displaybeep =-96 closelibrary =-414 openlib =-408 execbase = 4 getmsg =-372 joy2 =$dff0c fire =$bfe001 ;!!!when > 500kb !!! ;org $40000 ;load $40000 ; or use AssemPro to place in CHIP RAM ;!!!!!!!!!!!!!!!!!!!!!!! run: bsr openint bsr scropen bsr windopen bsr setmenu bsr print lea border,a1 move #22,d0 move #30,d1 bsr borderdraw bsr draw bsr request loop: move.l execbase,a6 move.l windowhd,a0 move.l 86(a0),a0 ;user port jsr getmsg(a6) tst.l d0 beq loop ;no event move.l d0,a0 move.l $16(a0),msg ;event:LO=item,HI=Event move.l msg,d6 ;to test move.l d6,d7 lsr #8,d7 lsr #3,d7 ;sub menu point in D7 clr.l d5 roxr #1,d6 roxl #1,d5 ;menu number in D5 and.l #$7f,d6 cmp #$7f,d6 ;no menu point? beq loop ;no:continue lsr #4,d6 ;menu point in D6 cmp #1,d6 ;point 2? bne no1 move,l intbase,a6 move.l screenhd,a0 jsr displaybeep(a6) no1: cmp #0,d6 bne loop ende: bsr clearmenu bsr windclose bsr scrclose bsr closeint rts openint: move.l execbase,a6 lea intname,a1 jsr openlib(a6) move.l d0,intbase rts closeint: move.l execbase,a6 move.l intbase,a1 jsr closelibrary(a6) rts scropen: move.l inbase,a6 lea screen_defs,a0 jsr openscreen(a6) move.l d0,screenhd scrclose: move.l inbase,a6 move.l screenhd,a0 jsr closescreen(a6) rts scrmove: move.l intbase,a6 move,l screenhd,a0 jsr movescreen(a6) rts windopen: move.l intbase,a6 lea windowdef,a0 jsr openwindow(a6) move.l d0,windowhd rts windclose: move.l intbase,a6 move.l windowhd,a0 jsr closewindow(a6) rts request: move.l windowhd,a0 lea btext,a1 lea ltext,a2 lea rtext,a3 move.l #0,d0 move.l #0,d1 move.l #180,d2 move.l #80,d3 move.l intbase,a6 jsr autorequest(a6) rts setmenu: lea mentab,a0 ;pointer to text pointer in A0 lea menu,a1 ;pointer to menu field in A1 move #10,d1 ;menu position = 10 menuloop: clr.l d2 ;menu point-Y=0 move.l a1,a2 ;save pointer tst.l (a0) beq setmenu1 ;end clr.l (a1)+ move d1,(a1)+ add.l #70,d1 move.l #50,(a1)+ move.l #$a0001,(a1)+ move.l (a0)+,(a1)+ ;menu title lea 12(a1),a3 move.l a3,(a1)+ ;menu point clr.l (a1)+ clr.l (a1)+ itemloop: tst.l (a0) ;last one? beq menuend ;yes lea 54(a1),a3 move.l a3,(a1)+ ;pointer to next point move.l d2,(a1)+ ;X/Y add #10,d2 move.l #$5a000a,(a1)+ ;width/height move #$52,(a1)+ clr.l (a1)+ lea 16(a1),a3 move.l a3,(a1)+ ;text structor-pointer clr.l (a1)+ clr.l (a1)+ clr.l (a1)+ move #$1,(a1)+ ;text-structor set clr (a1)+ move.l #$50003,(a1)+ clr.l (a1)+ move.l (a0)+,(a1)+ ;text pointer clr.l (a1)+ bra itemloop ;next point... menuend: clr.l -54(a1) tst.l (a0)+ tst.l (a0) ;still in menu? beq setmenu1 ;no:ready move.l a1,(a2) ;pointer to next menu bra menuloop ;and continue setmenu1: move.l intbase,a6 move.l windowhd,a0 lea menu,a1 jsr setmenustrip(a6) rts clearmenu: move.l intbase,a6 move.l windowhd,a0 jsr clearmenustrip(a6) rts print: move.l intbase,a6 move.l windowhd,a0 move.l 50(a0),a0 lea ggtext,a1 move.l #30,d0 ;X move.l #16,d1 ;Y jsr printitext(a6) rts draw: move.l intbase,a6 move.l windowhd,a0 move.l 50(a0),a0 lea image,a1 move.l #200,d0 move.l #100,d1 jsr drawimage(a6) rts borderdraw: move.l intbase,a6 move.l windowhd,a0 move.l 50(a0),a0 jsr drawborder(a6) rts screen_defs: dc.w 0,0 dc.w 640,200 dc.w 4 dc.b 0 dc.b 1 dc.w $800 dc.w 15 dc.l 0 dc.l tite1 dc.l 0 dc.l 0 windowdef: dc.w 10,20 dc.w 300,150 dc.b 0,1 dc.l $300 dc.l $100f dc.l gadget dc.l 0 dc.l windname screenhd: dc.l 0 dc.l 0 dc.w 200,40,600,200 dc.w $f btext: dc.b 3,3 dc.b 0 align dc.w 10,10 dc.l 0 dc.l bodytxt dc.l 0 bodytxt:dc.b "Requester-Text",0 align ltext: dc.b 3,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l lefttext dc.l 0 lefttext: dc.b "left",0 align rtext: dc.b 0,1 dc.b 0 align dc.w 5,3 dc.l 0 dc.l righttext dc.l 0 righttext: dc.b "right",0 align tite1: dc.b "User Screen",0 windname: dc.b "Window-Title",0 align windowhd: dc.l 0 intbase:dc.l 0 intname:dc.b "intuition.library",0 align msg:dc.l 0 mentab: dc.l menu1 dc.l mp11,np12,mp13,mp14,mp15,mp16,mp17,mp18,mp19,0 dc.l menu2 dc.l mp21,mp22,mp23,0 dc.l menu3 dc.l mp31,mp32,0 dc.l menu4,mp41,0 dc.l 0 menu1: dc.b "Menu 1",0 mp11: dc.b "Point 11",0 mp12: dc.b "Point 12",0 mp13: dc.b "Point 13",0 mp14: dc.b "Point 14",0 mp15: dc.b "Point 15",0 mp16: dc.b "Point 16",0 mp17: dc.b "Point 17",0 mp18: dc.b "Point 18",0 mp19: dc.b "Point 19",0 menu2: dc.b "Menu 2",0 mp21: dc.b "End!",0 mp22: dc.b "Beep",0 mp23: dc.b "Point 23",0 menu3: dc.b "Menu 3",0 mp31: dc.b "Point 31",0 mp32: dc.b "Point 32",0 menu4: dc.b "Menu 4",0 mp41: dc.b "Point 41",0 align gadget: dc.l gadget1 dc.w 20,80,80,10 dc.w 0 dc.w $2 ;activation,$802 for longint dc.w 4 dc.l border dc.l 0 dc.l 0 dc.l 0 dc.l strinfo dc.w 2 dc.l 0 border: dc.w 0,0 dc.b 1,0,0 dc.d 5 ;XY-pair dc.l koord dc.l 0 koord: dc.w -2,-2,80,-2,80,9,-2,9,-2,-2 strinfo: dc.l strpuffer dc.l undo dc.w 0 ;cursor position dc.w 10 ;max.char dc.w 0 dc.w 0,0,0,0,0 dc.l 0,0,0 strpuffer: dc.b "Hello!",0,0,0 undo: dc.l 0,0,0 align gadget1: dc.l gadget2 ;more gadget dc.w 40,50,32,13 dc.w $6 ;flags:invert dc.w $103 ;activate dc.w 1 ;gadget type dc.l image ;gadget image dc.l image2 ;select gadget dc.l ggtext ;gadget text dc.l 0 ;no exclude dc.l 0 ;special info dc.w 1 ;ID dc.l 0 ;user data ggtext: dc.b 1,0,1 align dc.w -8,14 dc.l 0 dc.l swtext dc,l 0 swtext: dc.b "Switch",0 align image: dc.w 0,0 dc.w 32,13 dc.w 1 dc.l imgdata dc.b 2,1 dc.l 0 image2: dc.w 0,0 dc.w 32,13 dc.w 1 dc.l imgdata2 dc.b 2,1 dc.l 0 imgdata: dc.l 0 dc.l %00000000011100000000000000000000 dc.l %00000000111110000011101001000000 dc.l %00000000111110000010101101000000 dc.l %00000000011110000010101011000000 dc.l %00000000000111000011101001000000 dc.l %00000000000011100000000000000000 dc.l %00000000000001110000000000000000 dc.l %00000000000111111111100000000000 dc.l %00000000001111111111110000000000 dc.l %00000000001111111111110000000000 dc.l %00000000000110000001100000000000 dc.l 0 imgdata2: dc.l 0 dc.l %00000000000000000000111000000000 dc.l %00011101110111000001111100000000 dc.l %00010101000100000001111100000000 dc.l %00010101100110000001111000000000 dc.l %00011101000100000011100000000000 dc.l %00000000000000000111000000000000 dc.l %00000000000000001110000000000000 dc.l %00000000000111111111100000000000 dc.l %00000000001111111111110000000000 dc.l %00000000001111111111110000000000 dc.l %00000000000110000001100000000000 dc.l 0 gadget2: dc.l 0 dc.w 150,30,100,50 dc.w 5 dc.w 2 dc.w 3 ;prop.gadet dc.l mover ;border dc.l 0,0,0 dc.l specinfo dc.w 3 dc.l 0 specinfo: dc.w 6 ;flags:free horiz dc.w 0,0 dc.w $ffff/10,$ffff/5 dc.w 0,0,0,0,0,0 mover: dc.w 0,0,16,7 dc.w 1 dc.l moverdata dc.b 1,0 dc.l 0 moverdata: dc.w %0111111111111110 dc.w %0101111111111010 dc.w %0101011111101010 dc.w %0101010110101010 dc.w %0101011111101010 dc.w %0101111111111010 dc.w %0111111111111110 menu:blk.w 500 end Chapter 8. ---------- 8.Advanced Programming. ----------------------- You've learned a lot about machine language programming on the Amiga.What you need yet are a few routines that can be used as programming tools.We'll work on that right now.They'll be easy to use in your own program.The sky's the limit now! 8.1.Supervisor Mode. -------------------- As mentioned in the chapter on the MC68000 processor,there are two operating modes:the User and the Supervisor mode.It is often necessary to move between the two modes.However,this isn't a simple process. The reason you want to do this,is that in User mode,you can't access the Status register.If you write to one of them,an Exception is executed which crashes the program. How can you get in Supervisor mode? No problem.The operating system of the Amiga contains a function in the EXEC library that lets you get into supervisor mode.Its called SuperState and it doesn't need any parameters.You can easily call this program by using the following lines: execbase = 4 ;exec base address superstate =-150 ;turn on function ... move.l execbase,a6 ;exec base address in A6 jsr superstate(a6) ;turn on supervisor mode move.l d0,savesp ;save return value ... savesp:blk.l 1 ;space for sp value You get the value of the Stack Pointer(SP)back in the D0 register. You'll also find it in register A7,but this register is changed regularly.The reason is that in Supervisor mode,the Amiga works with all the Interrupts and with the SP,and there are lots of Interrupts for this computor.We'll talk about interrupts in a bit. After this call,you'll use the user stack instead of the supervisor stack.In this way,you can access the old user stack.You need to make sure that the user stack is large enough since the interrupts must have enough room for their data on the stack. You need to save the value returned in D0,because you'll need this value later.You need to return to user mode sometime.Theres a function for this in the exec library as well.It is called the UserState function.It needs one parameter,the SP value that comes back from the SuperState function. Since you've saved this value in the long word starting at "savesp",you can write the following: userstate =-156 ... move.l execbase,a6 ;exec base address in A6 move.l savesp,d0 ;put old sp in D0 jsr userstate(a6) ;return to user mode Now you are back in the user mode.The user stack point(USP)is the same as before.You can write functions that need to be run from the supervisor mode as subroutines.First you call superstate,save the return value,execute the desired function,call userstate,and end with a RTS command.If the USP was changed,the RTS command would'nt work right,and the computor would jump who knows where and perhaps crash.Here it works though. Now comes the question:how does the operating system get the supervisor mode?Thats not too difficult;it goes like this: The superstate function attempts to access a Status Register.This causes an Exception to occur and a routine is called whose address begins at the long word starting at $20.It is the Exception Vector for Privilege Violation.The routine that it branches to is called in supervisor mode.Then it tests where this exception came from.If the routine finds that the exception comes from the superstate routine whose address it knows,the matter is settled.It just branches to the routine without turning off the user mode.Thats all there is to it. 8.2.Exception Programming. -------------------------- The exceptions described in the processor chapter offer you a lot of oppertunities to control the Amiga's functions.You can use them to specify how errors should be handled and even list a crash program. Here is a list of vectors that are used to jump to the exception routines: Number Address Use with ------------------------------------------------------------------ 2 $008 Bus error 3 $00C Address eror 4 $010 Illegal command 5 $014 Division by zero 6 $018 CHK command 7 $01C TRAPV command 8 $020 Privilege Violation 9 $024 Trace 10 $028 Axxx command emulation 11 $02C Fxxx command emulation $030-$038 Reserved 15 $03C Uninitialized interrupt $040-$05F Reserved 24 $060 Unauthorised interrupt 25-31 $064-$083 Level 1-7 interrupt 32-47 $080-$0BF TRAP commands $0C0-$0FF Reserved 64-255 $100-$3FF User interrupt vector Lets look at the TRAP commands as an example.They aren't used in the Amiga operating system.A TRAP command and a number between zero and fifteen are used to call one of the 16 posible TRAP routines.If the command TRAP #0 is executed,the processor (in supervisor mode)branches to the routine whose address lies at $80 in memory.This routine must end with a RTE(ReTurn from Exception) command. Some operating systems,for example,the ATARI ST's TOS operating systems,are completely callable via these TRAP's.Parameters are put on the stack,and then a TRAP command is executed.The advantage is that you don't have to know any of the operating systems addresses.In the Amiga you must know the addresses(Execbase=4). Lets write your own TRAP routine to demonstrate the use of the TRAP command.You'll need three program sections: 1.The initialization of the TRAP vector. 2.The TRAP routine itself(It must end with RTE). 3.A test routine that calls the TRAP command. Initialization is very short: init: move.l #trap0,$80 ;set vector for TRAP #0 rts Now you need to write the trap0 routine.Lets use the example from the hardware chapter that produced a beep. Lets write this routine using as little effort as possible.Change the RTS to a RTE at the end,erase the line in which the loop counter D0 was loaded for the tone production,and change the loop so that it works with long words.Now you can load the register with an arbitrary value and have the TRAP #0 followed by a peep of arbitrary duration. ;** beep tone production after a TRAP #0 ** ctlw =$dff096 ;DMA control c0thi =$dff0a0 ;HI table address c0tlo =c0thi+2 ;LO table address c0tl =c0thi+4 ;table length c0per =c0thi+6 ;read in rate c0vol =c0thi+8 ;volume trap0: ;* produce a short peep move.l #table,c0thi ;table beginning move #4,c0tl ;table length move #300,c0per ;read in rate move #40,c0vol ;volume move #$8201,ctlw ;start DMA (sound) loop: subq.l #1,d0 ;counter -1 bne loop ;count dwn to zero still: move #1,ctlw ;turn on tone rte ;exception end table: ;sound table dc.b -40,-70,-40,0,40,70,40,0 You need to make sure that "table"is in CHIP RAM($00000-$7FFFF), otherwise the sound chip can't access the data! After entering this,you can test it out using the following routine: test: move.l #$2ffff,d0 ;pass tone length in D0 trap #0 ;carry out exception:peep rts Now assemble both routines and start the initialization routine, init.Nothing happens. Start the second routine,test.A beep that lasts about one second is output. One thing you must keep in mind is that if you change the program and reassemble it,the address of the trap0 routine can change. Before you execute the TRAP command,you must repeat the initializ- ation,so that the computor doesn't jump to the wrong location! Appendices. ----------- Overview of Library Functions. ------------------------------ The following table gives you an overview of the available libraries and their functions.Each sublist of functions is preceded by the name of the library it is found in. These functions are listed with their negative offset in hex and decimal.Their name and their parameters are also specified.The parameter names are in parenthesis behind the function name.The second set of parenthesis includes a list of registers that correspond to the parameter names.If no parameters are needed,we put () to let you know. CLIST.LIBRARY -$001E -30 InitCLPool (cLPool,size) (A0,D0) -$0024 -36 AllocCList (cLPool) (A1) -$002A -42 FreeCList (cList) (A0) -$0030 -48 FlushCList (cList) (A0) -$0036 -54 SizeCList (cList) (A0) -$003C -60 PutCLChar (cList,byte) (A0,D0) -$0042 -66 GetCLChar (cList) (A0) -$0048 -72 UnGetCLChar (cList,byte) (A0,D0) -$004E -78 UpPutCLChar (cList) (A0) -$0054 -84 PutCLWord (cList,word) (A0,D0) -$005A -90 GetCLWord (cList) (A0) -$0060 -96 UnGetCLWord (cList,word) (A0,D0) -$0066 -102 UnPutCLWord (cList) (A0) -$006C -108 PutCLBuf (cList,buffer,length) (A0,A1,D1) -$0072 -114 GetCLBuf (cList,buffer,maxLength) (A0,A1,D1) -$0078 -120 MarkCList (cList,offset) (A0,D0) -$007E -126 IncrCLMark (cList) (A0) -$0084 -132 PeekCLMark (cList) (A0) -$008A -138 SplitCList (cList) (A0) -$0090 -144 CopyCList (cList) (A0) -$0096 -150 SubCList (cList,index,length) (A0,D0.D1) -$009C -156 ConcatCList (sourceCList,destCList) (A0,A1) CONSOLE.LIBRARY -$002A -42 CDInputHandler (events,device) (A0,A1) -$0030 -48 RawKeyConvert (events,buffer,length,keyMap) (A0,A1,D1,A2) DISKFONT.LIBRARY -$001E -30 OpenDiskFont (textAttr) (A0) -$0024 -36 AvailFonts (buffer,bufBytes,flags) (A0,D0,D1) DOS.LIBRARY -$001e -30 Open (name,access mode)(d1,d2) -$0024 -36 Close (file)(d1) -$002a -42 Read (file,buffer,length)(d1,d2,d3) -$0030 -48 Write (file,buffer,length)(d1,d2,d3) -$0036 -54 Input() -$003c -60 Output() -$0042 -66 Seek(file,position,offset)(d1,d2,d3) -$0048 -72 DeleteFile (name)(d1) -$004e -78 Rename(oldname,newname)(d1,d2) -$0054 -84 Lock(name,type)(d1,d2) -$005a -90 UnLock(lock)(d1) -$0060 -96 DupLock(lock)(d1) -$0066 -102 Examine(lock,fileinfoblock)(d1,d2) -$006c -108 ExNext(lock,fileinfoblock)(d1,d2) -$0072 -114 Info(lock,parameterblock)(d1,d2) -$0078 -120 CreateDir(name)(d1) -$007e -126 CurrentDir(lock)(d1) -$0084 -132 IoErr() -$008a -138 CreateProc(name,pri,seglist,stacksize)(d1,d2,d3,d4) -$0090 -144 Exit(returncode)(d1) -$0096 -150 LoadSeg(filename)(d1) -$009c -156 UnLoadSeg(segment)(d1) -$00a2 -162 Getpacket(wait)(d1) -$00a8 -168 Queuepacket(packet)(d1) -$00ae -174 DeviceProc(name)(d1) -$00be -180 SetComment(name,comment)(d1,d2) -$ooba -186 SetProtection(name,mask)(d1,d2) -$00c0 -192 DateStamp(date)(d1) -$00c6 -198 Delay(timeout)(d1) -$00cc -204 WaitForChar(file,timeout)(d1,d2) -$00d2 -210 ParentDir(lock)(d1) -$00d8 -216 IsInteractive(file)(d1) -$00de -222 Execute(string,file,file)(d1,d2,d3) EXEC.LIBRARY -$001e -30 Supervisor() -$0024 -36 ExitIntr() -$002a -42 Schedule() -$0030 -48 Reschedule() -$0036 -54 Switch() -$003c -60 Dispatch() -$0042 -66 Exception() -$0048 -72 InitCode(startclass,version)(d0,d1) -$004e -78 InitStruct(inittable,memory,size)(a1,a2,d0) -$0054 -84 MakeLibrary(funcinit,structinit,libinit,datasize, codesize)(a0,a1,a2,d0,d1) -$005a -90 MakeFunctions(target,functionarray,funcdispbase) (a0,a1,a2) -$0060 -96 FindResident(name)(a1) -$0066 -102 InitResident(resident,seglist)(a1,d1) -$006c -108 Alert(alertnum,parameters)(d7,a5) -$0072 -114 Debug() -$0078 -120 Disable() -$007e -126 Enable() -$0084 -132 Forbid() -$008a -138 Permit() -$0090 -144 SetSR(newsr,mask)(d0,d1) -$0096 -150 SuperState() -$009c -156 UserState(sysstack)(d0) -$00a2 -162 setIntVector(intnumber,interrupt)(d0,d1) -$00a8 -168 AddIntServer(intnumber,interrupt)(d0,d1) -$00ae -174 RemIntServer(intnumber,interrupt)(d0,d1) -$00b4 -180 Cause(interrup)(a1) -$00ba -186 Allocate(freelist,bytesize)(a0,d0) -$00c0 -192 Deallocate(freelist,memoryblock,bytesize)(a0,a1,d0) -$00c6 -198 AllocMem(bytesize,requirements)(d0,d1) -$00cc -204 AlloAbs(bytesize,location)(d0,a1) -$00d2 -210 FreeMem(memoryblock,bytesize)(a1,d0) -$00d8 -216 AvailMem(requirements)(d1) -$00de -222 AllocEntry(entry)(a0) -$00e4 -228 FreeEntry(entry)(a0) -$00ea -234 Insert(list,node,pred)(a0,a1,a2) -$00f0 -240 AddHead(list,node)(a0,a1) -$00f6 -246 AddTail(list,node)(a0,a1) -$00fc -252 Remove(node)(a1) -$0102 -258 RemHead(list)(a0) -$0108 -264 RemTail(list)(a0) -$010e -270 Enqueue(list,node)(a0,a1) -$0114 -276 FindName(list,name)(a0,a1) -$011a -282 AddTask(task,initpc,finalpc)(a1,a2,a3) -$0120 -288 RemTask(task)(a1) -$0126 -294 FindTask(name)(a1) -$012c -300 SetTaskPri(task,prority)(a1,d0) -$0132 -306 SetSignal(newsignals,signelset)(d0,d1) -$0138 -312 SetExcept(newsignals,signalset)(d0,d1) -$013e -318 Wait(signalset)(d0) -$0144 -324 Signal(task,signalset)(a1,d0) -$014a -330 AllocSignal(signalnum)(d0) -$0150 -336 FreeSignal(signalnum)(d0) -$0156 -342 AllocTrap(trapnum)(d0) -$015c -348 FreeTrap(trapnum)(d0) -$0162 -354 AddPort(port)(a1) -$0168 -360 RemPort(port)(a1) -$016e -366 PutMsg(port,message)(a0,a1) -$0174 -372 GetMsg(port)(a0) -$017a -378 ReplyMsg(message)(a1) -$0180 -384 WaitPort(port)(a0) -$0186 -390 FindPort(name)(a1) -$018c -396 AddLibrary(library)(a1) -$0192 -402 RemLibrary(library)(a1) -$0198 -408 OldOpenLibrary(libname)(a1) -$019e -414 CloseLibrary(library)(a1) -$01a4 -420 Setfunction(library,funcoffset,funcentry)(a1,a0,d0) -$01aa -426 SumLibrary(library)(a1) -$01b0 -432 AddDevice(device)(a1) -$01b6 -438 RemDevice(device)(a1) -$01bc -444 OpenDevice(devname,unit,iorequest,flags)(a0,d0,a1 ,d1) -$01c2 -450 CloseDevice(iorequest)(a1) -$01c8 -456 DoIO(iorequest)(a1) -$01ce -462 SendIO(iorequest)(a1) -$01d4 -468 CheckIO(iorequest)(a1) -$01da -474 WaitIO(iorequest)(a1) -$01e0 -480 AbortIO(iorequest)(a1) -$01e6 -486 AddResource(resource)(a1) -$01ec -492 RemResource(resource)(a1) -$01f2 -498 OpenResource(resname,version)(a1,d0) -$01f8 -504 RawIOInit() -$01fe -510 RawMayGetChar() -$0204 -516 RawPutChar(char)(d0) -$020a -522 RawDoFmt()(a0,a1,a2,a3) -$0210 -528 GetCC() -$0216 -534 TypeOfMem(address)(a1) -$021c -540 Procedure(semaport,bidmsg)(a0,a1) -$0222 -546 Vacate(semaport)(a0) -$0228 -552 OpenLibrary(libname,version)(a1,d0) GRAPHICS.LIBRARY -$001e -30 BltBitMap(scrbitmap,scrx,scry,destbitmap,destx, desty,sizex,sizey,minterm,mask,tempa) (a0,d0,d1,a1,d2,d3,d4,d5,d6,d7,a2) -$0024 -36 BltTemplate(source,scrx,scrmod,destrastport,destx, desty,sixex,sizey)(a0,d0,d1,a1,d2,d3,d4,d5) -$002a -42 ClearEOL(rastport)(a1) -$0030 -48 ClearScreen(rastport)(a1) -$0036 -54 TextLength(rastport,string,count)(a1,a0,d0) -$003c -60 Text(rastport,string,count)(a1,a0,d0) -$0042 -66 SetFont(rastportid,textfont)(a1,a0) -$0048 -72 OpenFont(textattr)(a0) -$004e -78 CloseFont(textfont)(a1) -$0054 -84 AskSoftStyle(rastport)(a1) -$005a -90 SetSoftStyle(rastport,style,enable)(a1,d0,d1) -$0060 -96 AddBob(bob,rastport)(a0,a1) -$0066 -102 AddVSprite(vsprite,rastport)(a0,a1) -$006c -108 DoCollision(rastport)(a1) -$0072 -114 DrawGList(rastport,viewport)(a1,a0) -$0078 -120 InitGels(dummyhead,dummytail,gelsinfo)(a0,a1,a2) -$007e -126 InitMasks(vsprite)(a0) -$0084 -132 RemIBob(bob,rastport,viewport)(a0,a1,a2) -$008a -138 RemVSprite(vsprite)(a0) -$0090 -144 SetCollision(type,routine,gelsinfo)(d0,a0,a1) -$0096 -150 SortGList(rastport)(a1) -$009c -156 AddAnimObj(obj,animationkey,rastport)(a0,a1,a2) -$00a2 -162 Animate(animationkey,rastport)(a0,a1) -$00a8 -168 etGBuffers(animationobj,rastport,doublebuffer)(a0, a1,d0) -$00ae -174 InitGMasks(animationobj)(a0) -$00b4 -180 GelsFuncE() -$00ba -186 GelsFuncF() -$00c0 -192 LoadRGB4(viewport,colurs,count)(a0,a1,d0) -$00c6 -198 InitRastPort(rastport)(a1) -$00cc -204 InitVPort(viewport)(a0) -$00d2 -210 MrgCop(view)(a1) -$00D8 -216 MakeVPort (view,viewPort) (A0,A1) -$00DE -222 LoadView (view) (A1) -$00E4 -228 WaitBlit () -$00EA -234 SetRast (rastPort,color) (A1,D0) -$00F0 -240 Move (rastPort,x,y) (A1,D0,D1) -$00F6 -246 Draw (rastPort,x,y) (A1,D0,D1) -$00FC -252 AreaMove (rastPort,x,y) (A1,D0,D1) -$0102 -258 AreaDraw (rastPort,x,y) (A1,D0,D1) -$0108 -264 AreaEnd (rastPort) (A1) -$010E -270 WaitTOF () -$0114 -276 QBlit (blit) (A1) -$011A -282 InitArea (areaInfo,vectorTable,vectorTableSize) (A0,A1,D0) -$0120 -288 SetRGB4 (viewPort,index,r,g,b) (A0,D0,D1,D2,D3) -$0126 -294 QBSBlit (blit) (A1) -$012C -300 BltClear (memory,size,flags) (A1,D0,D1) -$0132 -306 RectFill (rastPort,xl,yl,xu,yu) (A1,D0,D1,D2,D3) -$0138 -312 BltPattern (rastPort,ras,xl,yl,maxX,maxY, fillBytes) (A1,A0,D0,D1,D2,D3,D4) -$013E -318 ReadPixel (rastPort,x,y) (A1,D0,D1) -$0144 -324 WritePixel (rastPort,x,y) (A1,D0,D1) -$014A -330 Flood (rastPort,mode,x,y) (A1,D2,D0,D1) -$0150 -336 PolyDraw (rastPort,count,polyTable) (A1,D0,A0) -$0156 -342 SetAPen (rastPort,pen) (A1,D0) -$015C -348 SetBPen (rastPort,pen) (A1,D0) -$0162 -354 SetDrMd (rastPort,drawMode) (A1,D0) -$0168 -360 InitView (view) (A1) -$016E -366 CBump (copperList) (A1) -$0174 -372 CMove (copperList,destination,data) (A1,D0,D1) -$017A -378 CWait (copperList,x,y) (A1,D0,D10 -$0180 -384 VBeamPos () -$0186 -390 InitBitMap (bitMap,depth,width,height) (A0,D0,D1,D2) -$018C -396 ScrollRaster (rastPort,dX,dY,minx,miny,maxx, maxy) (A1,D0,D1,D2,D3,D4,D5) -$0192 -402 WaitBOVP (viewPort) (A0) -$0198 -408 GetSprite (simpleSprite,num) (A0,D0) -$019E -414 FreeSprite (num) (D0) -$01A4 -420 ChangeSprite (vp,simpleSprite,data) (A0,A1,A2) -$01AA -426 MoveSprite (viewPort,simpleSprite,x,y) (A0,A1,D0,D1) -$01B0 -432 LockLayerRom (layer) (A5) -$01B6 -438 UnlockLayerRom (layer) (A5) -$01BC -444 SyncSBitMap (1) (A0) -$01C2 -450 CopySBitMap (11,12) (A0,A1) -$01C8 -456 OwnBlitter () -$01CE -462 DisownBlitter () -$01D4 -468 InitTmpRas (tmpras,buff,size) (A0,A1,D0) -$01DA -474 AskFont (rastPort,textAttr) (A1,A0) -$01E0 -480 AddFont (textFont) (A1) -$01E6 -486 RemFont (textFont) (A1) -$01EC -492 AllocRaster (width,height) (D0,D1) -$01F2 -498 FreeRaster (planeptr,width,height) (A0,D0,D1) -$01F8 -504 AndRectRegion (rgn,rect) (A0,A1) -$01FE -510 OrRectRegion (rgn,rect) (A0,A1) -$0204 -516 NewRegion () -$020A -522 ** reserved ** -$0210 -528 ClearRegion (rgn) (A0) -$0216 -534 DisposeRegion (rgn) (A0) -$021C -540 FreeVPortCopLists (viewPort) (A0) -$0222 -546 FreeCopList (coplist) (A0) -$0228 -552 ClipBlit (srcrp,srcX,srcY,destrp,destX,destY, sizeX,sizeY,minterm) (A0,D0,D1,A1,D2,D3,D4,D5,D6) -$022E -558 XorRectRegion (rgn,rect) (A0,A1) -$0234 -564 FreeCprList (cprlist) (A0) -$023A -570 GetColorMap (entries) (D0) -$0240 -576 FreeColorMap (colormap) (A0) -$0246 -582 GetRGB4 (colormap,entry) (A0,D0) -$024C -588 ScrollVPort (vp) (A0) -$0252 -594 UCopperListInit (copperlist,num) (A0,D0) -$0258 -600 FreeGBuffers (animationObj,rastPort, doubleBuffer) (A0,A1,D0) -$025E -606 BltBitMapRastPort (srcbm,srcx,srcy,destrp, destX,destY,sizeX,sizeY,minter) (A0,D0,D1,A1,D2,D3,D4,D5,D6) ICON.LIBRARY -$001E -30 GetWBObject (name) (A0) -$0024 -36 PutWBObject (name,object) (A0,A1) -$002A -42 GetIcon (name,icon,freelist) (A0,A1,A2) -$0030 -48 PutIcon (name,icon) (A0,A1) -$0036 -54 FreeFreeList (freelist) (A0) -$003C -60 FreeWBOject (WBOject) (A0) -$0042 -66 AllocWBOject () -$0048 -72 AddFreeList (freelist,mem,size) (A0,A1,A2) -$004E -78 GetDiskObject (name) (A0) -$0054 -84 PutDiskObject (name,diskobj) (A0,A1) -$005A -90 FreeDiskObj (diskobj) (A0) -$0060 -96 FindToolType (toolTypeArray,typeName) (A0.A1) -$0066 -102 MatchToolValue (typeString,value) (A0,A1) -$006C -108 BumbRevision (newname,oldname) (A0,A1) INTUITION.LIBRARY -$001E -30 OpenIntuition () -$0024 -36 Intuition (ievent) (A0) -$002A -42 AddGadget (AddPtr,Gadget,Position) (A0,A1,D0) -$0030 -48 ClearDMRequest (Window) (A0) -$0036 -54 ClearMenuStrip (Window) (A0) -$003C -60 ClearPointer (Window) (A0) -$0042 -66 CloseScreen (Screen) (A0) -$0048 -72 CloseWindow (Window) (A0) -$004E -78 CloseWorkbench () -$0054 -84 CurrentTime (Seconds,Micros) (A0,A1) -$005A -90 DisplayAlert (AlertNumber,String,Height) (D0,A0,D1) -$0060 -96 DiplayBeep (Screen) (A0) -$0066 -102 DoubleClick (sseconds,smicros,cseconds, cmicros) (D0,D1,D2,D3) -$006C -108 DrawBorder (Rport,Border,LeftOffset,TopOffset) (A0,A1,D0,D1) -$0072 -114 DrawImage (RPort,Image,LeftOffset,TopOffset) (A0,A1,D0,D1) -$0078 -120 EndRequest (requester,window) (A0,A1) -$007E -126 GetDefPref (preferences,size) (A0,D0) -$0084 -132 GetPrefs (preferences,size) (A0,D0) -$008A -138 InitRequester (req) (A0) -$0090 -144 ItemAddress (MenuStrip,MenuNumber) (A0,D0) -$0096 -150 ModifyIDCMP (Window,Flags) (A0,D0) -$009C -156 ModifyProp (Gadget,Ptr,Reg,Flags,HPos,VPos, HBody,VBody) (A0,A1,A2,D0,D1,D2,D3,D4) -$00A2 -162 MoveScreen (Screen,dx,dy) (A0,D0,D1) -$00A8 -168 MoveWindow (Window,dx,dy) (A0,D0,D1) -$00AE -174 OffGadget (Gadget,Ptr,Req) (A0,A1,A2) -$00B4 -180 OffMenu (Window,MenuNumber) (A0,D0) -$00BA -186 OnGadget (Gadget,Ptr,Req) (A0,A1,A2) -$00C0 -192 OnMenu (Window,MenuNumber) (A0,D0) -$00C6 -198 OpenScreen (OSArgs) (A0) -$00CC -204 OpenWindow (OWArgs) (A0) -$00D2 -210 OpenWorkBench () -$00D8 -216 PrintIText (rp,itext,left,top) (A0,A1,D0,D1) -$00DE -222 RefreshGadgets (Gadgets,Ptr,Req) (A0,A1,A2) -$00E4 -228 RemoveGadgets (RemPtr,Gadget) (A0,A1) -$00EA -234 ReportMouse (Window,Boolean) (A0,D0) -$00F0 -240 Request (Requester,Window) (A0,A1) -$00F6 -246 ScreenToBack (Screen) (A0) -$00FC -252 SCreenToFront (Screen) (A0) -$0102 -258 SetDMRequest (Window,req) (A0,A1) -$0108 -264 SetMenuStrip (Window,Menu) (A0,A1) -$010E -270 SetPointer (Window,Pointer,Height,Width, XOFFset, YOFFset) (A0,A1,D0,D1,D2,D3) -$0114 -276 SetWindowTitles (Window,windowTitle, screenTitle) (A0,A1,A2) -$011A -282 ShowTitle (Screen,ShowIt) (A0,D0) -$0120 -288 SizeWindow (Windowmdx,dy) (A0,D0,D1) -$0126 -294 ViewAddress () -$012C -300 ViewPortAddress (Window) (A0) -$0132 -306 WindowToBack (Window) (A0) -$0138 -312 WindowToFront (Window) (A0) -$013E -318 WindowLimits (Window,minwidth,minheight, maxwidth, maxheight) (A0,D0,D1,D2,D3) -$0144 -324 SetPrefs (preferences,size,flag) (A0,D0,D1) -$014A -330 IntuiTextLength (itext) (A0) -$0150 -336 WBenchToBack () -$0156 -342 WBenchToFront () -$015C -348 AutoRequest (Window,Body,PText,NText,PFlag, NFlag,W,H) (A0,A1,A2,A3,D0,D1,D2,D3) -$0162 -354 BeginRefresh (Window) (A0) -$0168 -360 BuildSysRequest (Window,Body,PosText,NegText, Flags,W,H) (A0,A1,A2,A3,D0,D1,D2) -$016E -366 EndRefresh (Window,Complete) (A0,D0) -$0174 -372 FreeSysRequest (Window) (A0) -$017A -378 MakeScreen (Screen) (A0) -$0180 -384 RemakeDisplay () -$0186 -390 RethinkDisplay () -$018C -396 AllocRemember (RememberKey,Size,Flags) (A0,D0,D1) -$0192 -402 AlohaWorkBench (wbport) (A0) -$0198 -408 FreeRemember (RememberKey,ReallyForgot) (A0,D0) -$019E -414 LockIBase (dontknow) (D0) -$01A4 -420 UnlockIBase (IBLock) (A0) LAYERS.LIBRARY -$001E -30 InitLayers (li) (A0) -$0024 -36 CreateUpfrontLayer (li,bm,x0,y0,xl,yl,flags, bm2) A0,A1,D0,D1,D2,D3,D4,A2) -$002A -42 CreateBehindLayer (li,bm,x0,y0,xl,yl,flags, bm2) (A0,A1,D0,D1,D2,D3,D3,A2) -$0030 -48 UpfrontLayer (li,layer) (A0,A1) -$0036 -54 BehindLayer (li,layer) (A0,A1) -$003C -60 MoveLayer (li,layer,dx,dy) (A0,A1,D0,D1) -$0042 -66 SizeLayer (li,layer,dx,dy) (A0,A1,D0,D1) -$0048 -72 ScrollLayer (li,layer,dx,dy) (A0,A1,D0,D1) -$004E -78 BeginUpdate (layer) (A0) -$0054 -84 EndUpdate (layer) (A0) -$005A -90 DeleteLayer (li,layer) (A0,A1) -$0060 -96 LockLayer (li,layer) (A0,A1) -$0066 -102 UnlockLayer (li,layer) (A0,A1) -$006C -108 LockLayers (li) (A0) -$0072 -114 UnlockLayers (li) (A0) -$0078 -120 LockLayerInfo (li) (A0) -$007E -126 SwapBitRastPortClipRect (rp,cr) (A0,A1) -$0084 -132 WhichLayer (li,x,y) (A0,D0,D1) -$008A -138 UnlockLayerInfo (li) (A0) -$0090 -144 NewLayerInfo () -$0096 -150 DisposeLayerInfo (li) (A0) -$009C -156 FattenLayerInfo (li) (A0) -$00A2 -162 ThinLayerInfo (li) (A0) -$00A8 -168 MoveLayerInfrontOf (layer_to_move, layer_to_be_in_front_of) (A0,A1) MATHFFP.LIBRARY -$001E -30 SPFix (float) (D0) -$0024 -36 SPFit (integer) (D0) -$002A -42 SPCmp (leftFloat,right,Float) (D1,D0) -$0030 -48 SPTst (float) (D1) -$0036 -54 SPAbs (float) (D0) -$003C -60 SPNeg (float) (D0) -$0042 -66 SPAdd (leftFloat,rightFloat) (D1,D0) -$0048 -72 SPSub (leftFloat,rightFloat) (D1,D0) -$004E -78 SPMul (leftFloat,rightFloat) (D1,D0) -$0054 -84 SPDiv (leftFloat,rightFloat) (D1,D0) MATHIEEEDOUBBAS.LIBRARY -$001E -30 IEEEDPFix (integer,integer) (D0,D1) -$0024 -36 IEEEDPFit (integer) (D0) -$002A -42 IEEEDPCamp (integer,integer,integer,integer) (D0,D1,D2,D3) -$0030 -48 IEEEDPTst (integer,integer) (D0,D1) -$0036 -54 IEEEDPAbs (integer,integer) (D0,D1) -$003C -60 IEEEDPNeg (integer,integer) (D0,D1) -$0042 -66 IEEEDPAdd (integer,integer,integer,integer) (D0,D1,D2,D3) -$0048 -72 IEEEDPSub (integer,integer,integer,integer) (D0,D1,D2,D3) -$004E -78 IEEEDPMul (integer,integer,integer,integer) (D0,D1,D2,D3) -$0054 -84 IEEEDPDiv (integer,integer,integer,integer) (D0,D1,D2,D3) MATHTRANS.LIBRARY -$001E -30 SPAtan (float) (D0) -$0024 -36 SPSin (float) (D0) -$002A -42 SPCos (float) (D0) -$0030 -48 SPTan (float) (D0) -$0036 -54 SPSincos (leftFloat,rightFloat) (D1,D0) -$003C -60 SPSinh (float) (D0) -$0042 -66 SPCosh (float) (D0) -$0048 -72 SPTanh (float) (D0) -$004E -78 SPExp (float) (D0) -$0054 -84 SPLog (float) (D0) -$005A -90 SPPow (leftFloat,rightFloat) (D1,D0) -$0060 -96 SPSqrt (float) (D0) -$0066 -102 SPTieee (float) (D0) -$006C -108 SPFieee (float) (D0) -$0072 -114 SPAsin (float) (D0) -$0078 -120 SPAcos (float) (D0) -$007E -126 SPLog10 (float) (D0) POTGO.LIBRARY -$0006 -6 AllocPotBits (bits) (D0) -$000C -12 FreePotBits (bits) (D0) -$0012 -18 WritePotgo (word,mask) (D0,D1) TIMER.LIBRARY -$002A -42 AddTime (dest,src) (A0,A1) -$0030 -48 SubTime (dest,src) (A0,A1) -$0036 -54 CmpTime (dest,src) (A0,A1) TRANSLATOR.LIBRARY -$001E -30 Translate (inputString,inputLength, outputBuffer,bufferSize) (A0,D0,A1,D1) Abbreviations (symbols) used: label A label or address reg Register an Address register n dn Data register n source source operand dest destination operand address of register #n direct value GENERAL INSTRUCTIONS BCC label Conditional branch, depends on condition. BRA label Unconditional branch (Similar to JMP). BSR label Branch to subprogram. Return address is deposited on the stack, RTS causes return to that address. CHK ,dx Check data register for limits, activate the CHK instruction exception. DBCC reg,label Check condition, decrement on branch. JMP label Jump to address (Similar to BRA). JSR label Jump to a subroutine. Return address is deposited on stack, RTS causes return to that address. NOP No operation. RESET Reset peripherals (Caution!). RTE Return from exception. RTR Return with loading of flags. RTS Return from subroutine (After BSR or JSR). SCC Set a byte to -1 when condition is met. STOP Stop processing (Caution!). TRAP #n Jump to an exception. TRAPV Check overflow flag, then TRAPV exception. ARITHMETIC OPERATIONS WITH WHOLE NUMBERS ADD source,dest Binary addition. ADDA source,an Binary addition to an address register. ADDI #n, Addition with a constant. ADDQ #n, Fast addition of a constant which can be only from 1 to 8. ADDX source,dest Addition with transfer in X flag. CLR Clear an operand. CMP source,dest Comparison of two operands. CMPA ,an Comparison with an address register. CMPI #n, Comparison with a constant. CMPM source,dest Comparison of two memory operands. DIVS source,dest Sign-true division of a 32 bit destination by a 16 bit source operand. The result of the division is stored in the LO word of the destination, the remainder in the HI word. DIVU source,dest Division without regard to sign, similar to DIVS. EXT dn Sign-true expansion to twice original size (width) data unit. MULS source,dest Sign-true multiplication of two words into one word. MULU source,dest Multiplication without regard to sign, similar to MULS. NEG Negation of an operand (twos complement). SUB source,dest Binary subtraction. SUBA ,an Binary subtraction from an address register. SUBI #n, Subtraction of a constant. SUBQ #n, Fast subtraction of a three bit constant. SUBX source,dest Subtraction with transfer in X flag. TST Test operand and set N and Z flag. BINARY CODED DECIMAL NUMBERS ABCD source,dest Addition of two binary coded decimal numbers. NBCD source,dest Negation of a binary coded decimal number (nine complement). SBCD source,dest Subtraction of two binary coded decimal numbers. LOGICAL OPERATIONS AND source,dest Logic AND. ANDI #n, Logic AND with a constant. EOR source,dest Exclusive OR. EORI #n, Exclusive OR with a constant. NOT Inversion of an operand. OR source,dest Logic OR. ORI #n, Logic OR with a constant. TAS Check a byte and set bit 7. SINGLE BIT MANIPULATION BCHG #n, Change bit n(0 is changed to 1 and vice versa). BCLR #n, Clear bit n. BSET #n, Set bit n. BTST #n, Test bit n, result is desplayed in Z flag. SHIFT AND ROTATE OPERANDS NOTE: n indicates a register, # indicates a direct value which specifies the number of shiftings. AS n, Arithmetic shift to the left (*2^n) ASR n, Arithmetic shift to the right (/2^n) LSL n, Logic shift to the left. LSR n, Logic shift to the right. ROL n, Rotation left. ROR n, Rotation right. ROXL n, Rotation left with transfer in X flag. ROXR n, Rotation right with transfer in X flag. MOVE DATA INSTRUCTIONS EXG rn,rn Exchange two register contents (don't confuse with swap!). LEA ,an Load an effective address in address register an. LINK an,#n Build stack range. MOVE source,dest Carry value over from source to destination. MOVE SR, Transfer the status register contents. MOVE ,SR Transfer the status register contents. MOVE USP, Transfer the user stack pointer. MOVE ,USP Transfer the user stack pointer. MOVEA ,an Transfer a value to the address register an. MOVEM regs, Transfer several registers at once. MOVEM ,regs Transfer several registers at once. MOVEP source,dest Transfer data to peripherals. MOVEQ #n,dn Quickly transfer an eight bit constant to the data register dn. PEA Deposit an address on the stack. SWAP dn Swap the halves of the register (the upper 16 bit with the lower). UNLK an Unlink the stack.