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- ATARI
-MADMAC
-68000 Macro Assembler
-Reference Manual
- version 1.00
-\f
-MADMAC Version 1.07 release notes, January, 1990.
-
-
-Using .cargs used to cause subsequent global symbols to disappear from
-the symbol table. Now it doesn't.
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-A movem instruction with no register list (i.e. "movem.l (sp)+,")
-assembled without error; it now reports "missing regsiter list."
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-MADMAC Version 1.05 release notes, August, 1988.
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-This version of MadMac replaces version 1.00 and fixes some small bugs:
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- Symbols beginning with a capital L were not included in the
-object file output. They should have been (and now are) excluded only
-in AS68 compatibility mode, to avoid cluttering the output with
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-compiler-generated symbols.
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- Forward branches declared "short" (such as bras, dbra.s, bsr.$)
-but whose targets were too far away did not cause an assembly-time
-error; incorrect machine code was silently generated. They now cause
-assembly-time errors.
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- Symbols appeared in the object file symbol table in the order •
-they were referenced in the source, not the order they were declared.
-Now the order more nearly matches the order of declaration (but not
-perfectly).
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- The disp(And(n.$) addressing mode produced correct machine code,
-but incorrect output in the listing file. Now the output is correct.
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-NOTE: Every effort has been made to ensure the accuracy and robustness of this
-manual and the associated software. However, because Atari Corporation is con-
-stantly improving and updating its computer software, it is unable to guarantee
-the accuracy of printed or duplicated material after the date of publication and
-disclaims liability for changes, errors or omissions.
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-ATARI, the Atari logo, MEGA, and ST are trademarks or registered trademarks of
-Atari Corporation.
-Mark Williams is a trademark of Mark Williams Company.
-Motorola is a trademark of Motorola Inc.
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-Copyright ® 1986, 1987, Atari Corporation
-All rights reserved.
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-Reproduction of this document or the associated software is not allowed without
-the specific written consent of Atari Corporation.
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-Printed in USA.
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-Atari Document number C300341-001 Rev. A.
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- Contents
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-Introduction . . 2
- Getting Started . 2
-The Command Line 4
-Using MADMAC . . 7
- Example Command Lines 7
- Interactive Mode . 7
- Things You Should Be Aware Of . 8
- Forward Branches . 8
- Notes for AS68 users . . 9
- Notes for Mark Williams C Users . . . . . 9
- Using MADMAC as a Back-End to the Alcyon C Compiler . 10
- Text File Format . 10
-Source Format . . 11
- Statements . 11
- Equates . . 11
- Symbols and Scope 11
- Keywords . . 12
- Constants 13
- Strings . . 13
- Register Lists 13
-Expressions . . . 15
- Order of Evaluation 15
- Types . . 15
- Unary Operators . 16
- Binary Operators . 16
- Special Forms . 16
- Example Expressions . 17
-Directives . . 18
-88000 Mnemonics . 22
-Macros . . 24
- Macro Declaration . . 24
- Parameter Substitution 24
- Macro Invocation . . 25
- Example Macros . 26
- Repeat Blocks . . 27
-6502 Support . . . 28
- 6502 Addressing Modes . . 28
- 6502 Directives . . 28
- 6502 Object Code Format . 29
-Error Messages 30
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- MADMAC Reference Manual 1
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- Introduction
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- Introduction
- This document describes MADMAC, a fast macro assembler for the 68000. MAD-
- MAC currently runs on the Atari ST and under 4.2 BSD VAX UNIX. It was written
- at Atari Corporation by programmers who needed a high performance assembler
- for their work.
- MADMAC is intended to be used by programmers who write mostly in as-
- sembly language. It was not originally a back-end to a C compiler, therefore it
- has creature comfort that are usually neglected in such back-end assemblers. It
- supports include files, macros, symbols with limited scope, some limited control
- structures, and other features. MADMAC is also blindingly fast, another feature
- often sadly and obviously missing in today's assemblers.1
- MADMAC is not entirely compatible with the AS68 assembler provided with
- the original Atari ST Developer's Kit, but most changes are minor and a few minutes
- with an editor should allow you to assemble your current source files. If you are an
- AS68 user, before you leap into the unknown please read the section on Notes for
- AS68 Users.
- This manual was typeset with TEX and the Computer Modern fonts, and it
- was printed on the Atari SLM-804 laser printer with a MEGA ST. Except for 200
- lines of assembly language, the assembler is written entirely in C.
- Getting Started
- =>Write protect your distribution disk and make a backup of it now. Put the
- original disk in a safe place.
- o The distribution disk contains a file called README that you should read.
- This file contains important nays about the contents of the distribution disk
- and summarizes the most recent changes to the tools.
- o Hard disk users can simply copy the executable files to their work or binary
- directories. People with floppy disks can copy the executables to ramdisks,
- install the assembler with the -q option, or even work right off of the floppies.
- o You will need an editor that can produce "normal" format text files. Micro
- Emacs will work well, as will most other commercial program editors, but not
- most word processors (such as First Word or Microsoft Write).
- o You will probably want to examine or get a listing of the file "ATARI.S". It
- contains lots of definitions for the Atari ST, including BIOS variables, most
- BIOS, XBIOS and GEMDOS traps, and line-A equates. We (or you) could
- split the file up into pieces (a file for line-A equates, a file for hardware and
-
- 1 It processes 30,000 lines a minute on a lightly loaded VAX 11/780; maybe
- 40,000 on a 520-ST with an SH-204 hard disk. Yet it could be sped up even more
- with some effort and without resorting to assembly language; C doesn't have to be
- slow!
-
- 2 MADMAC Reference Manual
-\f
- Introduction
-
- BIOS variables and so on), but MADMAC is so fast that it doesn't matter
- much.
- o Read the rest of the manual, especially the first two chapters on The Com-
- mand Line and Using MADMAC. The distribution disk contains example
- programs that you can look at, assemble and modify.
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- MADMAC Reference Manual 3
-
-\f
- The Command Line
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- The assembler is called "mac.prg". The command line takes the form:
-
- mac [switches] [files ...]
-
- A command line consists of any number of switches followed by the names of files
- to assemble. A switch is specified with a dash (-) followed immediately by a key
- character. Key characters are not case-sensitive, so "-d" is the same as "-D". Some
- switches accept (or require) arguments to immediately follow the key character,
- with no spaces in between.
- Switch order is important. Command lines are processed from left to right in
- one pass, and switches usually take effect when they are encountered. In general it
- is best to specify all switches before the names of any input files.
- If the command line is entirely empty then MADMAC prints a copyright mes-
- sage and enters an "interactive" mode, prompting for successive command lines
- with a star (*). An empty command line will exit (See the examples in the chapter
- on Using MADMAC). After each assembly in interactive mode, the assembler
- will print a summary of the amount of memory used, the amount of memory left,
- the number of lines processed, and the number of seconds the assembly took.
-
- Input files are assumed to have the extension ".s"; if a filename has no extension
- (i.e. no dot) then ".s" will be appended to it. More than one source filename may be
- specified: the files are assembled into one object file, as if they were concatenated.
- MADMAC normally produces object code in "file.o" if "file.s" is the first
- input filename. If the first input file is a special character device, the output name
- is noname.o. The -o switch (see below) can be used change the output file name.
-
-
- Switch Description
- -dname[=value] Define symbol, with optional value.
- -e[file[.err]] Direct error messages to the specified file.
- -fm Produce Mark Williams format object file.
- -fmu Like "-fm" , but move underscores to end of symbol names.
- -ipath Set include-file directory search path.
- -l[file[prn]] Construct and direct assembly listing to the specified file.
- -ofile[.o] Direct object code output to the specified file.
- -p Produce an executable (.prg) output file.
- -ps Produce an executable (.prg) output file with symbols.
- -q Make MADMAC resident in memory (Atari ST only).
- -s Warn about unoptimized long branches.
- -u Assume that all undefined symbols are external.
- -v Verbose mode (print running dialogue).
- -yn Set listing page size to n lines.
- -6 "Back end" mode for Alcyon C68.
- file[s] Assemble the specified file.
-
-
- 4 MADMAC Reference Manual
-\f
- The Command Line
-
- The switches are described below. A summary of all the switches is given in
-the table.
--d
- The -d switch permits symbols to be defined on the command line. The name
- of the symbol to be defined immediately follows the switch (no spaces). The
- symbol name may optionally be followed by an equals sign (=) and a decimal
- number. If no value is specified the symbol's value is zero. The symbol at-
- tributes are "defined, not referenced, and absolute". This switch is most useful
- for enabling conditionally-assembled debugging code on the command line; for
- example:
- -dDEBUG -dLoopCount=999 -dDebugLevel=55
--e
- The -e switch causes MADMAC to send error messages to a file, instead of the
- console. If a filename immediately follows the switch character, error messages
- are written to the specified file. If no filename is specified, a file is created with
- the default extension ".err" and with the root name taken from the first input
- file name (e.g. error messages are written to "file.err" if "file" or "file.s" is
- the first input file name). If no errors are encountered, then no error listing
- file is created. Beware! If an assembly produces no errors, any error file from
- a previous assembly is not removed.
--fm
--fmu
- The -fm and -fmu switches cause MADMAC to generate Mark Williams style
- object files instead of Alcyon object files. These files may be linked with the
- Mark Williams linker. The -fmu switch causes underscores on the first char-
- acter of a global symbol name to be moved to the end of the name, as per the
- Mark Williams C compiler naming convention. That is, "_main" will become
- "main_" and "__main" will become "_main_".
-
- The -i switch allows automatic directory searching for include files. A list of
- semi-colon seperated directory search paths may be mentioned immediately
- following the switch (with no spaces anywhere). For example:
- -im:;c:include;c:include\sys
- will cause the assembler to search the current directory of device M, and the
- directories include and include\sys on drive C. If -1 is not specified, and the
- enviroment variable "MACPATH" exists, its value is used in the same manner.
- For example, users of the Mark Williams shell could put the following line in
- their profile script to achieve the same result as the -i example above:
- setenv MACPATH="m:;c:include;c:include\sys"
--l
- The -l switch causes MADMAC to generate an assembly listing file. If a file-
- name immediately follows the switch character, the listing is written to the
- specified file. If no filename is specified, then a listing file is created with the
- default extension ".prn" and with the root name taken from the first input file
- name (e.g. the listing is written to "file.prn" if "file" or "file.s" is the first
- input file name).
--o
- The -o switch causes MADMAC to write object code on the specified file. No
- default extension is applied to the filename. For historical reasons the filename
- can also be seperated from the switch with a space (e.g. "-o file").
-
- MADMAC Reference Manual 5
-
-\f
- The Command Line
-
-
-
- -p
- -ps
- The -p and -ps switches cause MADMAC to produce an Atari ST executable
- file with the default extension of ".prg". If there are any external references
- at the end of the assembly, an error message is emitted and no executable file
- is generated. The -p switch does not write symbols to the executable file. The
- -ps switch includes symbols (Alcyon format) in the executable file.
-
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- -q
- The -q switch is aimed primarily at users of floppy-disk-only systems. It causes
- MADMAC to install itself in memory, like a RAMdisk. Then the program
- m.prg (which is very short - less than a sector) can be used instead of
- mac.prg, which can take ten or twelve seconds to load.
-
- -s
- The -s switch causes MADMAC to generate a list of unoptimized forward
- branches as warning messages. This is used to point out branches that could
- have been short (e.g. "bra" could be "bra.s").
-
- -u
- The -u switch takes effect at the end of the assembly. It forces all referenced
- and undefined symbols to be global, exactly as if they had been made global
- with a .extern or .globl directive. This can be used if you have a lot of
- external symbols, and you don't feel like declaring them all external.
-
- -v
- The -v switch turns on a "verbose" mode in which MADMAC prints out (for
- example) the names of the files it is currently processing. Verbose mode is
- automatically entered when MADMAC prompts for input with a star.
-
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- -y
- The -y switch, followed immediately by a decimal number (with no intervening
- space), sets the number of lines in a page. MADMAC will produce N lines
- before emitting a form-feed. If N is missing or less than 10 an error message is
- generated.
-
- -6
- The -6 switch takes effect when it is mentioned. It allows MADMAC to be
- used as a back end to the Alcyon C compiler.1 Note: the assembler will
- produce code that is typically ten percent larger and ten percent slower than
- the output of the Alcyon assembler, therefore use of this switch for production
- code is discouraged.
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- 1 The -6 switch is not a compatibility mode for AS68 - it has been carefully
- tailored to accept the output of the Alcyon C compiler.
-
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- 6 MADMAC Reference Manual
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- Using MADMAC
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- Let's assemble and link some example programs. These programs are included
-on the distribution disk in the "EXAMPLES" directory - you should copy them to
-your work area before continuing. In the following examples we adopt the conven-
-tions that the shell prompt is a percent sign (%) and that your input (the stuff you
-type) is presented in bold face.
- If you have been reading carefully, you know that MADMAC can generate
-an executable file without linking. This is useful for making small, stand alone
-programs that don't require externals or library routines. For example, the following
-two commands:
- % mac examples
- % aln -s example.s
-could be replaced by the single command:
- % mac -ps example.s
-since you don't need the linker for stand-alone object files.
- Successive source files named in the command line are are concatenated, as in
-this example, which assembles three files into a single executable, as if they were
-one big file:
- % mac -p bugs shift images
-Of course you can get the same effect by using the .include directive, but sometimes
-it is convenient to do the concatenation from the command line.
- Here we have an unbelievably complex command line:
- % mac -lzorf -y95 -o tmp -ehack -Ddebug=123 -ps example
-This produces a listing on the file called "zorf.pni" with 95 lines per page, writes
-the executable code (with symbols) to a file called "tmp.prg," writes an error list-
-ing to the file "hack.err," specifies an include-file path that includes the current
-directory on the drive "K:," defines the symbol "debug" to have the value 123, and
-assembles the file "example.s". (Take a deep breath - you got all that?)
- One last thing. If there are any assembly errors, MADMAC will terminate
-with an exit code of 1. If the assembly succeeds (no errors, although there may be
-warnings) the exit code will be 0. This is primarily for use with "make" utilities.
-
-Interactive Mode
-If you invoke MADMAC with an empty command line it will print a copyright
-message and prompt you for more commands with a star (*). This is useful if you
-are used to working directly from the desktop, or if you want to assemble several files
-in succession without having to reload the assembler from disk for each assembly.
- In interactive mode, the assembler is also in verbose mode (just as if you had
-specified -v on each command line):
-
- MADMAC Reference Manual 7
-
-\f
- Using MADMAC
-
- %. mac
-
- MADMAC Atari Macro Assembler
- Copyright 1987 Atari Corporation
- Beta version 0.12 Jun 1987 lmd
-
- * -ps example
- [Including: example.s]
- [Including: atari.s]
- [Leaving: atari.s]
- [Leaving; example. a]
- [Writing executable tile: example.prg
- 36K used, 3868K left, 850 lines, 2.0 seconds
- *
-
- You can see that the assembler gave a "blow-by-blow" account of the files it pro-
- cessed, as well as a summary of the assembly's memory usage, the number of lines
- processed (including macro and repeat-block expansion), and how long the assembly
- took
- The assembler prompts for another command with the star. At this point you
- can either type a new command line for the assembler to process, or you can exit
- by typing control-C or an empty line.
-
- Things You Should Be Aware Of
- MADMAC is a one pass assembler. This means that it gets all of its work done by
- reading each source file exactly once and then "back-patching" to fix up forward
- references. This one-pass nature is usually transparent to the programmer, with
- the following important exceptions:-
- o in listings, the object code for forward references is not shown. Instead, lower-
- case "xx"s are displayed for each undefined byte, as in the following example:
- 60xx 1: bra.s.2 ;forward branch
- xxxxxxxx dc.l .2 ;forward reference
- 60FE .2: bra.s.2 ;backward reference
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- o Forward branches (including BSRs) are never optimized to their short forms.
- To get a short forward branch it is necessary to explicitly use the ".s" suffix in
- the source code.
- o Error messages may appear at the end of the assembly, refering to earlier source
- lines that contained undefined symbols.
- o All object code generated must fit in memory. Running out of memory is a
- fatal error that you must deal with by splitting up your source files, re-sizing
- or eliminating memory-using programs such as ramdisks and desk accessories,
- or buying more RAM.
-
- Forward Branches
- MADMAC does not optimize forward branches for you, but it will tell you about
- them if you use the -s (short branch) option:
- % mac -s example.s
- "example.s", line 20: warning: unoptimized short branch
- With the -e option you can redirect the error output to a file, and determine by
- hand (or editor macros) which forward branches are safe to explicitly declare short.
-
- 8 MADMAC Reference Manual
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-\f
- Using MADMAC
-Notes for AS68 Users
-MADMAC is not entirely compatible with the Alcyon assembler, AS68. This section
-outlines the major differences. In practice, we have found that very few changes are
-necessary to make AS68 source code assemble.
- o A semicolon (;) must be used to introduce a comment, except that a star (*)
- may be used in the first column. AS68 treated anything following the operand
- field, preceeded by whitespace, as a comment. (MADMAC treats a star that
- is not in column 1 as a multiplication operator).
- o Labels require colons (even labels that begin in column 1).
- o Conditional assembly directives are called if, else and endif. AS68 called these
- ifne, ifeq (etc.), and endc.
- o The tilde (~) character is an operator, and back-quote (`) is an illegal character.
- AS68 permitted the tilde and back-quote characters in symbols.
- o There are no equivalents to AS68's org or section directives. AS68's page
- directive has become eject. The AS68 .xdef and .xref directives are not imple-
- mented, but .globl makes these unnecessary anyway. The directives .comline,
- mask2, idnt and opt, which were unimplemented and ignored in AS68, are
- not legal in MADMAC.
- o The location counter cannot be manipulated with a statement of the form:
- * = expression
- o The ds directive is not permitted in the text or data segments (except in -6
- mode); an error message is issued. Use dcb instead to reserve large blocks of
- initialized storage.
- o Back-slashes in strings are "electric" characters that are used to escape C-like
- character codes. Watch out for GEMDOS path names in ASCII constants -
- you will have to convert them to double-backslashes.
-
-Notes for Mark Williams C Users
-MADMAC will generate object code that the Mark Williams C linker, ld, will
-accept. This has been tested only with version 2.0 of the Mark Williams package.
-Some notable differences between MADMAC and the Mark Williams assembler, as,
-are:
- o MWC permits 16-character symbol names in the object file, and MADMAC
- supports this;
- o MWC object files can contain more code and data sections than the MADMAC
- (Alcyon) object code format. MADMAC maps its code sections as follows:
- MWC Space MADMAC Space
- shui (shared instruction) text
- prvi (private instruction) unsupported
- bssi (uninitialized instruction) unsupported
- shrd (shared data) data
- prvd (private data) unsupported
- bssd (uninitialized data) bss
- debug information unsupported
- symbols symbols
- absolute abs, equates, etc.
-
- MADMAC Reference Man real 9
-
-
-\f
- Using MADMAC
-
- It is not possible for MADMAC to generate code in the Mark Williams private
- instruction, private data or uninitialized instruction spaces.
- o None of the Mark Williams assembler directives (e.g. ".long" and ". odd") are
- supported. None of the MWC non-standard addressing modes are supported.
- o The Mark Williams debugger, db, does not support the Alcyon-format symbols
- produced with the -ps switch; it complains about the format of the executable
- file and aborts.
- o MADMAC does not support the method by which the Mark Williams shell
- passes long command lines to programs. Command lines are truncated to 127
- characters.
-
- Using MADMAC as a Back-End to the Alcyon C Compiler
- MADMAC can be used in place of the AS68 assembler as a back-end for the Alcyon
- version 4.14 C compiler. The "-6" switch turns on a mode that warps and perverts
- MADMAC's ordinary syntax into accepting what the Alcyon compiler dishes out.
- This can be used in a batch file (for instance) with a line that looks like:
- mac -6 -o %1.o m:%1
- (Assuming that device "M:" is where the source was put by compiler phase c168).
- You should be aware that AS68 generally produces better and faster code than
- MADMAC, although it is slower to assemble.
-
- Text File Format
- For those using editors other than the "Emacs" style ones (Micro-Emacs, Mince,
- etc.) this section documents the source file format that MADMAC expects.
- o Files must contain characters with ASCII values less than 128; it is not per-
- missable to have characters with their high bits set unless those characters are
- contained in strings (i.e. between single or double quotes) or in comments.
- o Lines of text are terminated with carriage-return/line-feed, linefeed alone, or
- carriage-return alone.
- o The file is assumed to end with the last terminated line. If there is text beyond
- the last line terminator (e.g. control-Z) it is ignored.
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- 10 MADMAC Reference Manual
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- Source Format
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-Statements
-A statement may contain up to four fields which are identified by order of ap-
-pearance and terminating characters. The general form of an assembler statement
-is:
- label: operator operand(s) ; comment
- The label and comment fields are optional. An operand field may not appear
-without an operator field. Operands are seperated with commas. Blank lines are
-legal. If the first character on a line is an asterisk (*) or semicolon (;) then the
-entire line is a comment. A semicolon anywhere on the line (except in a string)
-begins a comment field which extends to the end of the line.
- The label, if it appears, must be terminated with a single or double colon. If
-it is terminated with a double colon it is automatically declared global. It is illegal
-to declare a confined symbol global (see: Symbols and Scope).
-Equates
-A statement may also take one of these special forms:
- symbol equ expression
- symbol = expression
- symbol -- expression
- symbol set expression
- symbol reg register list
- The first two forms are identical; they equate the symbol to the value of an
-expression, which must be defined (no forward references). The third form, double-
-equals (==), is just like an equate except that it also makes the symbol global. (As
-with labels, it is illegal to make a confined equate global.) The fourth form allows
-a symbol to be set to a value any number of times, like a variable. The last form
-equates the symbol to a 16-bit register mask specified by a register list. It is possible
-to equate confined symbols (see: Symbols and Scope). For example:
- cr equ 13 carriage-return
- if = 10 line-feed
- DEBUG == 1 global debug flag
- count set 0 variable
- count set count + 1 increment variable
- .rags reg d3-d7/a3-a6 register list
- .cr 13 confined equate
-Symbols and Scope
-Symbols may start with an uppercase or lowercase letter (A-Z a-z), an underscore
-(_), a question mark (7) or a period ( ). Each remaining character may be an
-upper or lowercase letter, a digit (0-9), an underscore, a dollar sign ($), or a ques-
-tion mark. (Periods can only begin a symbol, they cannot appear as a symbol
-
- MADMAC Reference Manual 11
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-\f
- Source Format
-
- continuation character). Symbols are terminated with a character that is not a
- symbol continuation character (e.g. a period or comma, whitespace, etc.). Case is
- significant for user-defined symbols, but not for 68000 mnemonics, assembler direc-
- tives and register names. Symbols are limited to 100 characters. When symbols
- are written to the object file they are silently truncated to eight (or sixteen) char-
- acters (depending on the object file format) with no check for (or warnings about)
- collisions.
- For example, all of the following symbols are legal and unique:
- reallyLougSymbolliame .reallyLongConfinadSymbollame
- al0 ret move dc frog aae a9 ????
- .al .ret .move .dc .frog .a9 .9 ????
- .0 .00 .000 .1 .11. .111 . ._
- _frog ?zippo? sys$syetem atari Atari ATARI aTaRi
- while all of the following symbols are illegal:
- 12days dc.10 dc.z 'quote .right.here
- @work hi.there $money$ ~tilde
- Symbols beginning with a period (.) are confined; their scope is between two
- normal (unconfined) labels. Confined symbols may be labels or equates. It is illegal
- to make a confined symbol global (with the ".globl" directive, a double colon, or a
- double equals). Only unconfined labels delimit a confined symbol's scope; equates
- (of any kind) do not count. For example, all symbols are unique and have unique
- values in the following:
- zero:: subq.w $1,d1
- bmi.s .ret
- .loop: clr.w (a0)+
- dbra d0,.loop
- .ret: rta
- FF:: subq.w #1,d1
- bmi.s .99
- .loop: move.w -1,(a0)+
- dbra d0,.loop
- .99: its
- Confined symbols are useful since the programmer has to be much less inventive
- about finding small, unique names that also have meaning.
- It is legal to define symbols that have the same names as processor mnemonics
- (such as "move" or "rts") or assembler directives (such as ".even"). Indeed, one
- should be careful to avoid typographical errors, such as this classic (in 6502 mode):
- .6502
- .org = $8000
- which equates a confined symbol to a hexadecimal value, rather than setting the
- location counter, which the .org directive does (without the equals sign).
- Keywords
- The following names, in all combinations of uppercase and lowercase, are keywords
- and may not be used as symbols (e.g. labels, equates, or the names of macros):
- equ set reg
- sr ccr pc sp ssp usp
- dO di d2 d3 d4 d5 d6 d7
- a0 al a2 a3 a4 a5 a6 aT
- r0 ri r2 r3 r4 r5 r6 r7
- r8 r9 r10 1'11 r12 rl3 ri4 ri5
-
- 12 MADMAC Reference Manual
-•
-\f
- Source Format
-
-Constants
-Numbers may be decimal, hexadecimal, octal, binary or concatenated ASCII. The
-default radix is decimal, and it may not be changed. Decimal numbers are specified
-with a string of digits (0-9). Hexadecimal numbers are specified with a leading
-dollar sign ($) followed by a string of digits and uppercase or lowercase letters (A-F
-a-f). Octal numbers are specified with a leading at-sign (@) followed by a string
-of octal digits (0-7). Binary numbers are specified with a leading percent sign
-(%) followed by a string of binary digits (0-1). Concatenated ASCII constants are
-specified by enclosing from one to four characters in single or double quotes. For
-example:
-
- 1234 decimal
- $1234 hexadecimal
- @777 octal
- %10111 binary
- "z" ASCII
- 'frog' ASCII
-
-Negative numbers Are specified with a unary minus (-). For example:
-
- -5678 -@334 -$4e71
- -%11011 -'z' -"WIND"
-
-Strings
-Strings are contained between double (") or single ( ') quote marks. Strings may
-contain non-printable characters by specifying "backslash" escapes, similar to the
-ones used in the C programming language. MADMAC will generate a warning if a
-backslash is followed by a character not appearing below:
-
- \\ $5c backslash
- \n $0a line-feed (newline)
- \b $08 backspace
- \t $09 tab
- \r $0c1 carriage-return
- \f $0c form-feed
- \e $1b escape
- \' $27 single-quote
- \" $22 double-quote
-
- It is possible for strings (but not symbols) to contain characters with their high
-bits set (i.e. character codes 128...255).
- You should be aware that backslash characters are popular in GEMDOS path
-names, and that you may have to escape backslash characters in your existing source
-code. For example, to get the file "c:\euto\andi.s" you would specify the string
-"c:\\auto\\andi.s".
-
-Register Lists
-Register lists are special forms used with the movem mnemonic and the .reg
-directive. They are 16-bit values, with bits 0 through 15 corresponding to registers
-D0 through A7. A register list consists of a series of register names or register
-ranges seperated by slashes. A register range consists of two register names, Rm
-and Rn,m<n, seperated by a dash. For example:
-
- MADMAC Reference Manual 13
-
-
-\f
- Source Format
-
- register list value
- ------------- -----
- 40-d7/a0-a7 $FFFF
- d2-d7/a0/a3-a6 $39FC
- dO/d1/a0-a3/d7/a6-a7 $CF83
- d0 $0001
- r0-r16 $FFFF
- Register lists and register equates may be used in conjunction with the movem
- mnemonic, as in this example:
- temps reg d0-d2/a0-a2 ; temp registers
- keeps reg d3-d7/d3-a6 ; registers to preserve
- allregs reg d0-d7/a0-a7 ; all registers
- movem.l #temps, -(sp) ; these two lines ...
- aovea.l dO -d2/a0 -a2, -(sp) ; are identical
- movea.l #keeps, -(sp) ; save "keep" registers
- noven.1 (sp)+,#keeps ; restore "keep" registers
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- 14 MADMAC Reference Manual
-
-\f
- Expressions
-
-
-
-
-
-
-
-All values are computed with 32-bit 2's complement arithmetic. For boolean op-
-erations (such as if or assert) zero is considered false, and non-zero is considered
-true.
- Expressions are evaluated strictly left-to-right, with no
- regard for operator precedence.
-Thus the expression "1+2*3" evaluates to 9, not 7. However, precedence may be
-forced with parenthesis (()) or square-brackets ([]).
-
-Types
-Expressions belong to one of three classes: undefined, absolute or relocatable. An
-expression is undefined if it involves an undefined symbol (e.g. an undeclared sym-
-bol, or a forward reference). An expression is absolute if its value will not change
-when the program is relocated (for instance, the number 0, all labels declared in
-an abs section, and all Atari ST hardware register locations are absolute values).
-An expression is relocatable if it involves exactly one symbol that is contained in a
-text, data or BSS section.
- Only absolute values may be used with operators other than addition (+) or
-subtraction (-). It is illegal, for instance, to multiply or divide by a relocatable or
-undefined value. Subtracting a relocatable value from another relocatable value in
-the same section results in an absolute value (the distance between them, positive
-or negative). Adding (or subtracting) an absolute value to or from a relocatable
-value yeilds a relocatable value (an offset from the relocatable address).
- It is important to realize that relocatable values belong to the sections they
-are defined in (e.g. text, data or BSS), and it is not permissible to mix and match
-sections. For example, in this code:
- linel: dc.l line2, linel+8
- line2: dc.l linel, line2-8
- line3: dc.l line2-linel, 8
- error: dc.l linel+line2, line2 >> 1, line3/4
-Line 1 deposits two longwords that point to line 2. Line 2 deposits two longwords
-that point to line 1. Line 3 deposits two longwords that have the absolute value
-eight. The fourth line will result in an assembly error, since the expressions (re-
-spectively) attempt to add two relocatable values, shift a relocatable value right by
-one, and divide a relocatable value by four.
- The pseudo-symbol "*" (star) has the value that the current section's location
-counter had at the beginning of the current source line. For example, these two
-statements deposit three pointers to the label "bar":
- too: dc.l *+4
- bar: dc.l *, *
-
- Similarly, the pseudo-symbol "$" has the value that the current section's loca-
-tion counter has, and it is kept up to date as the assembler deposits information
-
- MADMAC Reference Manual 15
-
-\f
- Expressions
-
-
-
- "across" a line of source code. For example, these two statements deposit four
- pointers to the label "zip":
-
-
- zip: dc.l $+8, $+4
- zop: dc.l $, $-4
-
-
- Unary Operators
-
- Operator Description
- - Unary minus (2's complement).
- ! Logical (boolean) NOT.
- ~ Tilde: bitwise not (l's complement).
- ^^defined symbol True if symbol has a value.
- ^^referenced symbol True if symbol has been referenced.
- ^^streq stringl,string2 True if the strings are equal.
- ^^macdef macroName True if the macro is defined.
-
- o The boolean operators generate the value 1 if the expression is true, and 0 if
- it is not.
-
- o A symbol is referenced if it is involved in an expression. A symbol may have
- any combination of attributes: undefined and unreferenced, defined and unref-
- erenced (i.e. declared but never used), undefined and referenced (in the case
- of a forward or external reference), or defined and referenced.
-
-
-
- Binary Operators
-
- Operator Description
- + - * / The usual arithmetic operators.
- % Modulo.
- & | ^ Bit-wise AND, OR and Exclusive-OR.
- << >> Bit-wise shift left and shift right.
- < <= >= > Boolean magnitude comparisons.
- = Boolean equality.
- <> != Boolean inequality.
-
- o All binary operators have the same precedence: expressions are evaluated
- strictly left to right.
-
- o Division or modulo by zero yields an assembly error
-
- o The "<>" and "!=" operators are synonyms.
-
- o Note that the modulo operator (%) is also used to introduce binary constants
- (see: Constants). A percent sign should be followed by at least one space if
- it is meant to be a modulo operator, and is followed by a '0' or '1'.
-
- Special Forms
-
- Special Form Description
- ^^date The current system date (Gemdos format).
- ^^time The current system time (Gemdos format).
-
- o The "^^date" special form expands to the current system date, in Gemdos
- format. The format is a 16-bit word with bits 0 ...4 indicating the day of the
- month (1...31), bits 5...8 indicating the month (1...12), and bits 9...15
- indicating the year since 1980, in the range 0...119.
-
- 16 MADMAC Reference Manual
-
-\f
- Expressions
-
- o The "^^time" special form expands to the current system time, in Gemdos
- format. The format is a 16-bit word with bits 0...4 indicating the current
- second divided by 2, bits 5...10 indicating the current minute 0...59. and
- bits 11...15 indicating the current hour 0...23.
-
-Example Expressions
-
- line address contents source code
- ---- ------- -------- -------------------------------
- 1 00000000 4480 lab1: neg.l d0
- 2 00000002 427900000000 lab2: clr.w lab1
- 3 =00000064 equ1 = 100
- 4 =00000096 equ2 = equ1 + 50
- 5 00000008 00000064 dc.l lab1 + equ1
- 6 0000000C 7FFFFFE6 dc.l (equl + ~equ2) >> 1
- 7 00000010 0001 dc.w ^^defined equl
- 8 00000012 0000 dc.w ^^referenced lab2
- 9 00000014 00000002 dc.l lab2
- 10 00000018 0001 dc.w ^^referenced lab2
- 11 0000001A 0001 dc.w lab1 = (lab2 - 6)
-Lines 1 through four here are used to set up the rest of the example. Line 5 deposits
-a relocatable pointer to the location 100 bytes beyond the label "lab1." Line 6 is
-a nonsensical expression that uses the and right-shift operators. Line 7 deposits
-a word of 1 because the symbol "equ1" is defined (in line 3).
- Line 8 deposits a word of 0 because the symbol "lab2," defined in line 2, has
-not been referenced. But the expression in line 9 references the symbol "lab2," so
-line 10 (which is a copy of line-8) deposits a word of 1. Finally, line 11 deposits a
-word of 1 because the Boolean equality operator evaluates to true.
- The operators "^^defined" and "^^referenced" are particularly useful in
-conditional assembly. For instance, it is possible to automatically include debugging
-code if the debugging code is referenced, as in:
- lea string,a0 ; AO -> message
- jsr debug ; print a message
- its ; and return
- string: dc.b "Help me, Spock!",0 ; (the message)
-
- .iif ^^defined debug, .include "debug.s"
-The jsr statement references the symbol debug. Near the end of the source file, the
-".iif' statement includes the file "debug.s" if the symbol debug was referenced.
-In production code, presumably all references to the debug symbol will be removed,
-and the debug source file will not be included. (We could have as easily made the
-symbol debug external, instead of including another source file).
-
-
-
-
-
-
-
-
-
-
-
-
- MADMAC Reference Manual 17
-\f
- Directives
-
-
-
-
-
-
-
-
-
-
- Assembler directives may be any mix of upper- or lowercase. The leading periods
- are optional, though they are shown here and their use is encouraged. Directives
- may be preceeded by a label; the label is defined before the directive is executed.
- Some directives accept size suffixes (.b, .s, .w or .1); the default is word (.w) if no
- size is specified. The .s suffix is identical to .b. Directives relating to the 6502 are
- described in the chapter on 6502 Support.
-
-
-
-
- .even
- If the location counter for the current section is odd, make it even by adding
- one to it. In text and data sections a zero byte is deposited if necessary.
- .assert expression [,expression...]
- Assert that the conditions are true (non-zero). If any of the comma-seperated
- expressions evaluates to zero an assembler warning is issued. For example:
- .assert *-start = $76
- .assert stacksize >= $400
- .bss
- .data
-• .text
- Switch to the BSS, data or text segments. Instructions and data may not
- be assembled into the BSS-segment, but symbols may be defined and storage
- may be reserved with the As directive. Each assembly starts out in the text
- segment.
- .abs [location]
- Start an absolute section, beginning with the specified location (or zero, if
- no location is specified). An absolute section is much like BSS, except that
- locations declared with .ds are based absolute. This directive is useful for
- declaring structures or hardware locations.
- For example, the following equates:
- VPLANES = 0
- VWRAP = 2
- CONTRL = 4
- INTIN = 8
- PTSIN = 12
- could be as easily defined as:
- .abs
- VPLAIES: ds.w 1
- VWRAP: ds.w 1
- CONTRL: ds.l 1
- INTIE: ds.l 1
- PTSIN: ds.l 1
-
-• 18 MADMAC Reference Manual
-\f
- Directives
-
-.comm symbol, expression
- Specifies a label and the size of a common region. The label is made global,
- thus confined symbols cannot be made common. The linker groups all com-
- mon regions of the same name; the largest size determines the real size of the
- common region when the file is linked.
-
-.dc[.size] expression [,expression...]
- Deposit initialized storage in the current section. If the specified size is word
- or long, the assembler will execute a .even before depositing data. If the size
- is .b, then strings that are not part of arithmetic expressions are deposited
- byte-by-byte. If no size is specified, the default is .w. This directive cannot be
- used in the BSS section.
-
-.dcb[.size] expression 1, expression2
- Generate an initialized block of expression) bytes, words or longwords of the
- value expression2. If the specified size is word or long, the assembler will
- execute .even before generating data. If no size is specified, the default is .w.
- This directive cannot be used in the BSS section.
-
-.ds[.size] expression
- Reserve space in the current segment for the appropriate number of bytes,
- words or longwords. If no size is specified, the default size is .w. If the size
- is word or long, the assembler will execute .even before reserving space. This
- directive can only be used in the BSS or ABS sections (in text or data, use
- .dcb to reserve large chunks of initialized storage.)
-
-.init[.size] [#expression,]expression[.size] [,...]
- Generalized initialization directive. The size specified on the directive becomes
- the default size for the rest of the line. (The "default" default size is .w.) A
- comma-seperated list of expressions follows the directive; an expression may be
- followed by a size to override the default size. An expression may be preceeded
- by a sharp sign, an expression and a comma, which specifies a repeat count to
- be applied to the next expression. For example:
- .init.l -1, 0.w, #16,'z'.b, #3,0, 11.b
-
- will deposit a longword of -1, a word of zero, sixteen bytes of lower-case 'z',
- three longwords of zero, and a byte of 11.
- No auto-alignment is performed within the line, but a .even is done once
- (before the first value is deposited) if the default size is word or long.
-
-.cargs [#expression dsymboi[.size] [, symbol[.size].. .]
- Compute stack offsets to C (and other language) arguments. Each symbol is
- assigned an absolute value (like equ) which starts at expression and increases
- by the size of each symbol, for each symbol. If the expression is not supplied,
- the default starting value is 4. For example:
- .cargs #8, .fileliams.1, .openMode, .butPointer.l
-
- could be used to declare offsets from A6 to a pointer to a filename, a word
- containing an open mode, and a pointer to a buffer. (Note that the symbols
- used here are confined). Another example, a C-style "string-length" function,
- could be written as.
-
- MADMAC Reference Manual 19
-
-\f
- Directives
- _strlen:: .cargs .string ; declare arg
- move.l .string(sp),a0 ; a0 -> string
- moveq #-1,d0 ; initial size = -1
- .1: addq.1 #1,d0 ; bump size
- tst.b (a0)+ ; at end of string?
- bne .1 ; (no -- try again)
- rts ; return string length
- .end
- End the assembly. In an include file, end the include file and resume assembling
- the superior file. This statement is not required, nor are warning messages
- generated if it is missing at the end of a file. This directive may be used inside
- conditional assembly, macros or .rept blocks.
- .if expression
- .else
- .endif
- Start a block of conditional assembly. If the expression is true (non-zero) then
- assemble the statements between the .if and the matching .endif or .else.
- If the expression is false, ignore the statements unless a matching .else is
- encountered. Conditional assembly may be nested to any depth.
- It is possible to exit a conditional assembly block early from within an include
- file (with end) or a macro (with endni).
- .iif expression, statement
- Immediate version of if. If the expression is true (non-zero) then the state-
- ment, which may be an instruction, a directive or a macro, is executed. If
- the expression is false, the statement is ignored. No .endif is required. For
- example:
- .iif age < 21, canDrink = 0
- .iif weight > 500, dangerFlag = 1
- .iif !(^^defined DEBUG), .include dbsrc
- .macro name [formal, formal,...]
- .endim
- .exitm
- Define a macro called name with the specified formal arguments. The macro
- definition is terminated with a .endm statement. A macro may be exited early
- with the .exitm directive. See the chapter on Macros for more information.
- .undefmac macroName [, macroNarne. .]
- Remove the macro-definition for the specified macro names. If reference is
- made to a macro that is not defined, no error message is printed and the name
- is ignored.
- .rept expression
- .endr
- The statements between the .rept and .endr directives will be repeated ex-
- pression times. If the expression is zero or negative, no statements will be
- assembled. No label may appear on a line containing either of these directives.
- .globl symbol [, symbol...]
- .extern symbol [, symbol...]
- Each symbol is made global. None of the symbols may be confined symbols
- (those starting with a period). If the symbol is defined in the assembly, the
- symbol is exported in the object file. If the symbol is undefined at the end
- of the assembly, and it was referenced (i.e. used in an expression), then the
-
- 20 MADMAC Reference Manual
-
-\f
- Directives
-
-
- symbol value is imported as an external reference that must be resolved by the
- linker. The .extern directive is merely a. synonym for
-
-.include "file"
- Include a file. If the filename is not enclosed in quotes, then a default extension
- of ".s" is applied to it. If the filename is quoted, then the name is not changed
- in any way.
-
- Note: If the filename is not a valid symbol, then the assembler will generate an
- error message. You should enclose filenames such as "atari.s" in quotes,
- because such names are not symbols.
-
- If the include file cannot be found in the current directory, then the direc-
- tory search path, as specified by -i on the commandline, or' by the NACPLTH
- enviroment string, is traversed
-
-.eject
- Issue a page eject in the listing file.
-
-.title "string"
-.subttl [-] "string"
- Set the title or subtitle on the listing page. The title should be specified on
- the the first line of the source program in order to take effect on the first page.
- The second and subsequent uses of .title will cause page ejects. The second
- and subsequent uses of .subttl will cause page ejects unless the subtitle string
- is preceeded by a dash (-).
-
-.list
-.nlist
- Enable or disable source code listing. These directives increment and decrement
- an internal counter, so they may be appropriately nested. They have no effect
- if the -l switch is not specified on the commandline.
-
-.goto label
- This directive provides unstructured flow of control within a macro definition.
- It will transfer control to the line of the macro containing the specified goto
- label. A goto label is a symbol preceeded by a colon that appears in the first
- column of a source line within a macro definition:
-
- : label
-
- where the label itself can be any valid symbol name, followed immediately by
- whitespace and a valid source line (or end of line). The colon must appear in
- the first column.
- The goto-label is removed from the source line prior to macro expansion -
- to all intents and purposes the label is invisible except to the .goto directive
- Macro expansion does not take place within the label.
- For example, here is a silly way to count from 1 to 10 without using .rept:
-
- .macro Count
- count set 1
- :loop dc.w count
- count set count + 1
- iif count <= 10, goto loop
- .endm
-
-
-
-
-
-
-
-
- MADMAC Reference Manual 21
-
-
-\f
- 68000 Mnemonics
-
-
-
-
-
-
-
-
-
-
- Mnemonics
- All of the standard Motorola 68000 mnemonics and addressing modes are supported;
- you should refer to The Motorola M68000 Programmer's Reference Manual
- for a description of the instruction set and the allowable addressing modes for each
- instruction. With one major exception (forward branches) the assembler performs
- all the reasonable optimizations of instructions to their short or address register
- forms.
- Register names may be in upper or lower case. The alternate forms R0 through
- R15 may be used to specify D0 through A7. All register names are keywords, and
- may not be used as labels or symbols. None of the 68010 or 68020 register names
- are keywords (but they may become keywords in the future).
-
- Addressing Modes
- Assembler Syntax Description
- Dn Data register direct
- An Address register direct
- (An) Address register indirect
- (An)+ Address register indirect postincrement
- -(An) Address register indirect predecrement
- disp(An) Address register indirect with displacement
- bdisp(An, Xi[.size]) Address register indirect indexed
- abs.w Absolute short
- abs Absolute (long or short)
- abs.l Forced absolute long
- disp(PC) Program counter with displacement
- bdisp(PC, Xi) Program counter indexed
- #imm Immediate
-
-
- Branches
- Since MADMAC is a one pass assembler, forward branches cannot be automatically
- optimized to their short form. Instead, unsized forward branches are assumed to
- be long. Backward branches are always optimized to the short form if possible.
- A table that lists "extra" branch mnemonics (common synonyms for the Mo-
- torola defined mnemonics) appears below.
-
- Linker Constraints
- It is not possible to make an external reference that will fix up a byte. For example:
-
- extern frog
- move.l frog(pc,d0),d1
-
- 22 MADMAC Reference Manual
-\f
-68000 Mnemonics
-Branch Synonyms
-Alternate name Becomes:
-bhs bcc
-blo bcs
-bse, bs beq
-bns bne
-dblo dbcs
-dbse dbeq
-dbra dbf
-dbhs dbhi
-dbns dbne
-is illegal (and generates an assembly error) when frog is external, because the
-displacement occupies a byte field in the 68000 offset word, which the object file
-cannot represent.
-Optimizations and Translations
-The assembler provides "creature comforts" when it processes 68000 mnemonics:
-
-o CLR.x An will really generate SUB.x An,An.
-o ADD, SUB and CMP with an address register will really generate ADDA,
-SUBA and CMPA.
-o The ADD, AND, CMP, EOR, OR and SUB mnemonics with immediate
-first operands will generate the "I" forms of their instructions (ADDI, etc.) if
-the second operand is not register direct.
-o All shift instructions with no count value assume a count of one.
-o MOVE.L is optimized to MOVEQ if the immediate operand is defined and
-in the range -128...127. However, ADD and SUB are never translated to
-their quick forms; ADDQ and SUBQ must be explicit.
-MADMAC Reference Manual 23
-
-\f
- Macros
-
-
-
-
-
-
-
- A macro definition is a series of statements of the form:
- .macro name [ formal-arg, ...]
-
- statements making up the macro body
-
- .endm
-
- The name of the macro may be any valid symbol that is not also a 68000 instruction
- or an assembler directive. (The name may begin with a period - macros cannot
- be made confined the way labels or equated symbols can be). The formal argument
- list is optional; it is specified with a comma-seperated list of valid symbol names.
- Note that there is no comma between the name of the macro and the name of the
- first formal argument
- A macro body begins on the line after the .macro directive. All instructions
- and directives, except other macro definitions, are legal inside the body.
- The macro ends with the .endm statement. If a label appears on the line with
- this directive, the label is ignored and a warning is generated.
-
- Parameter Substitution
- Within the body, formal parameters may be expanded with the special forms:
- \name
- \{name}
-
- The second form (enclosed in braces) can be used in situations where the characters
- following the formal parameter name are valid symbol continuation characters. This
- is usually used to force concatentation, as in:
- \{frog}star
- \(godzilla}vs\{reagan}
-
- The formal parameter name is terminated with a character that is not valid in
- a symbol (e.g. whitespace or puncuation); optionally, the name may be enclosed in
- curly-braces. The names must be symbols appearing on the formal argument list,
- or a single decimal digit (\1 corresponds to the first argument, \2 to the second,
- \9 to the ninth, and \0 to the tenth). It is possible for a macro to have more than
- ten formal arguments, but arguments 11 and on must be referenced by name, not
- by number.
- Other special forms are:
-
- 24 MADMAC Reference Manual
-
-\f
- Macros
-
- Special Form Description
- \\ a single "\",
- \~ a unique label of the form "Mn"
- \# the number of arguments actually specified
- \! the "dot-size" specified on the macro invocation
- \?name conditional expansion
- \?{name} conditional expansion
-
- The last two forms are identical: if the argument is specified and is non-empty, the
- form expands to a "1", otherwise (if the argument is missing or empty) the form
- expands to a "0".
- The form "\!" expands to the "dot-size" that was specified when the macro
- was invoked. This can be used to write macros that behave differently depending
- on the size suffix they are given, as in this macro which provides a synonym for the
- "dc" directive:
- .macro deposit value
- dc\! \value
- .endm
- deposit.b 1 ; byte of 1
- deposit.w 2 ; word of 2
- deposit.l 3 ; longvord of 3
- deposit 4 ; word of 4 (no explicit size)
-
- Macro Invocation
- A previously-defined macro is called when its name appears in the operation field of
- a statement. Arguments may be specified following the macro name; each argument
- is seperated by a comma. Arguments may be empty. Arguments are stored for
- substitution in the macro body in the following manner:
- o Numbers are converted to hexadecimal.
- o All spaces outside strings are removed.
- o Keywords (such as register names, dot sizes and "^^" operators) are converted
- to lowercase.
- o Strings are enclosed in double-quote marks (").
- For example, a hypothetical call to the macro "mymacro", of the form:
- mymacro A0, , 'Zorch' / 32, "^^DEFINED foo, , , tick tock
- will result in the translations:
- Argument Expansion Comment
- \1 a0 "A0" converted to lower-case
- \2 empty
- \3 "Zorch"/$20 "Zorch" in double-quotes, 32 in hexadecimal
- \4 "^^defined foo" "^^DEFINED" converted to lower-case
- \5 empty
- \6 empty
- \7 ticktock spaces removed (note concatenation)
-
- The .exitm directive will cause an immediate exit from a macro body. Thus
- the macro definition:
-
- MADMAC Reference Manual 25
-
-\f
- Macros
- .macro foo source
- .iif !\?source, .exitm ; exit if source is empty
- move \source,d0 ; otherwise, deposit source
- .endm
-
- will not generate the move instruction if the argument "source" is missing from
- the macro invocation.
- The .end, .endif and .exitm directives all pop-out of their include levels
- appropriately. That is, if a macro performs a include to include a source file, an
- executed .exitm directive within the include-file will pop out of both the include-file
- and the macro.
- Macros may be recursive or mutually recursive to any level, subject only to
- the availability of memory. When writing recursive macros, take care in the coding
- of the termination condition(s). A macro that repeatedly calls itself will cause the
- assembler to exhaust its memory and abort the assembly.
-
-
- Example Macros
-
- The Gemdos macro is used to make file system calls. It has two parameters, a
- function number and the number of bytes to clean off the stack after the call. The
- macro pushes the function number onto the stack and does the trap to the file
- system. After the trap returns, conditional assembly is used to choose an addq or
- an add.w to remove the arguments that were pushed.
- .macro Gemdos trpno, clean
- move.w #\trpno,-(sp) ; push trap number
- trap #1 ; do GEMDOS trap
- .if \clean <= 8 ;
- addq Aclean,sp ; clean-up up to 8 bytes
- .else ;
- add.w $\clean,sp ; clean-up more than 8 bytes
- .endif
- .endm
-
- The Fopen macro is supplied two arguments; the address of a filename, and
- the open mode. Note that plain move instructions are used, and that the caller of
- the macro must supply an appropriate addressing mode (e.g. immediate) for each
- argument.
- .macro Fopen file, mode
- movs.w \mode,-(sp) ;push open mode
- move.1 \file,-(sp) ;push address of tile name
- Gemdos $3d,8 ;do the GEMDOS call
- .endm
-
- The String macro is used to allocate storage for a string, and to place the
- string's address somewhere. The first argument should be a string or other expres-
- sion acceptable in a dc.b directive. The second argument is optional; it specifies
- where the address of the string should be placed. If the second argument is omitted,
- the string's address is pushed onto the stack. The string data itself is kept in the
- data segment.
-
-26 MADMAC Reference Manual
-
-\f
- Macros
-
- .macro String str,loc
- .if \?loc ; if lac is defined
- move.l #.\~,\loc ; put the string's address there
- .else ; otherwise
- pea .\~ ; push the string's address
- .endif ;
- .data ; put the string data
- .\~: dc.b \str,0 ; in the data segment
- .text ; and switch back to the text segment
- .endm
-
- The construction ".\~" will expand to a label of the form ".Mn" (where n is
-a unique number for every macro invocation), which is used to tag the location of
-the string. The label should be confined because the macro may be used along with
-other confined symbols.
- Unique symbol generation plays an important part in the art of writing fine
-macros. For instance, if we needed three unique symbols, we might write ".a\~",
-".b\~" and ".c\~".
-
-Repeat Blocks
-Repeat-blocks provide a simple iteration capability. A repeat block allows a range
-of statements to be repeated a specified number of times. For instance, to generate
-a table consisting of the numbers 255 through 0 (counting backwards) you could
-write:
-
- .count set 255 ; initialize counter
- .rept 256 ; repeat 256 times:
- dc.b .count ; deposit counter
- .count set .count - 1 ; and decrement it
- .endr ; (end of repeat block)
-
-Repeat blocks can also be used to duplicate identical pieces of code (which are
-common in bitmap-graphics routines). For example:
-
- .rept 16 ; clear 16 words
- clr.w (a0)+ ; starting at AO
- .endr ;
-
-
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- MADMAC Reference Manual 27
-
- •
-\f
- 6502 Support
-
-
-
-
-
-
-
-
- MADMAC will generate code for the Motorola 6502 microprocessor. This chapter
- describes extra addressing modes and directives used to support the 6502.
- As the 6502 object code is not linkable (currently there is no linker) external
- references may not be made. (Nevertheless, MADMAC may reasonably be used for
- large assemblies because of its blinding speed.)
- All standard 6502 addressing modes are supported, with the exception of the
- accumulator addressing form, which must be omitted (e.g. "ror a" becomes "ror").
- Five extra modes, synonyms for existing ones, are included for compatibility with
- the Atari Coinop assembler.
- empty implied or accumulator (e.g. tsx or ror)
- expr absolute or zeropage
- *expr immediate
- (expr,x) indirect X
- (expr),y indirect Y
- (expr) indirect
- @expr,x indexed X
- @expr,y indexed Y
- @expr(x) indirect X
- x,expr(y) indirect Y
- y,expr indirect
- • x,expr indexed X
- y,expr indexed Y
- While MADMAC lacks "high" and "low" operators, high bytes of words may
- be extracted with the shift (>>) or divide (/) operators, and low bytes may be
- extracted with the bitwise AND (&) operator.
- .6502
- This directive enters the 6502 section. The location counter is undefined, and
- must be set with ".org" before any code can be generated.
- The "dc.w" directive will produce 6502-format words (low byte first). The
- 68000's reserved keywords (d0-d7/a0-a7/ssp/usp and so on) remain reserved
- (and thus unusable) while in the 6502 section. The directives globl, dc.l,
- dcb.l, text, data, bas, abs, even and comm are illegal in the 6502 section.
- It is permitted, though probably not useful, to generate both 6502 and 68000
- code in the same object file.
- .68000
- This directive leaves the 6502 segment and returns to the 68000's text segment.
- 68000 instructions may be assembled as normal.
- .org location
- This directive is only legal in the 6502 section. It sets the value of the location
- counter (or pc) to location, an expression that must be defined, absolute, and
- less than $10000.
-
- 28 MADMAC Reference Manual
-
-\f
- 6502 Support
-
- WARNING
- It is possible to assemble "beyond" the microprocessor's 64K address space, but
- attempting to do so will probably screw up the assembler. DO NOT attempt
- to generate code like this:
- .org $fffe
- nop
- nop
- nop
- the third NOP in this example, at location $10000, may cause the assembler
- to crash or exhibit spectacular schizophrenia. In any case, MADMAC will give
- no warning before flaking out.
-
-Object Code Format
-This is a little bit of a kludge. An object file consists of a page map, followed by
-one or more page images, followed by a normal Alcyon 68000 object file. If the page
-map is all zero, it is not written.
- The page map contains a byte for each of the 256 256-byte pages in the 6502's
-64K address space. The byte is zero ($00) if the page contained only zero bytes, or
-one ($01) if the page contained any non-zero bytes. If a page is flagged with a one,
-then it is written (in order) following the page map.
- The following code:
- .6502
- .org $8000
- .dc.b 1
- .org $8100
- .dc.b 1
- .org $8300
- .dc.b 1
- .end
-will generate a page map that looks (to a programmer) something like:
- <80 bytes of zero>
- 01 01 00 01
- <$7c more bytes of zero, for $100 total>
- <image of page $80>
- <image of page $81>
- <image of page $83>
- Following the last page image is an Alcyon-format object file, starting with
-the magic number $601a. It may contain 68000 code (although that is probably
-useless), but the symbol table is valid and available for debugging purposes. 6502
-symbols will be absolute (not in text, data or bss).
-
-
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- MADMAC Reference Manual 29
-
-\f
- Error Messages
-
-
-
-
-
-
-
-
- When Things Go Wrong
- Most of MADMAC's error messages are self-explanatory. They fall into four classes:
- warnings about situations that you (or the assembler) may not be happy about,
- errors that cause the assembler to not generate object files, fatal errors that cause
- the assembler to abort immediately, and internal errors that should never happen.1
- You can write editor macros (or sed or awk scripts) to parse the error messages
- MADMAC generates. When a message is printed, it is of the form:
- "filename" , line line-number: message
- The first element, a filename enclosed in double quotes, indicates the file that gen-
- erated the error. The filename is followed by a comma, the word "line", and a line
- number, and finally a colon and the text of the message. The filename "(*top*)"
- indicates that the assembler could not determine which file had the problem.
- The following sections list warnings, errors and fatal errors in alphabetical
- order, along with a short description of what may have caused the problem.
-
- Warnings
- bad backslash code in string
- You tried to follow a backslash in a string with a character that the assembler
- didn't recognize. Remember that MADMAC uses a C-style escape system in
- strings.
- label ignored
- You specified a label before a macro, rept or endm directive. The assembler
- is warning you that the label will not be defined in the assembly.
- unoptimized short branch
- This warning is only generated if the -s switch is specified on the command
- line. The message refers to a forward, unsized long branch that you could have
- made short (.s).
-
- Fatal Errors
- cannot continue
- As a result of previous errors, the assembler cannot continue processing. The
- assembly is aborted.
- line too long as a result of macro expansion
- When a source line within a macro was expanded, the resultant line was too
- long for MADMAC (longer than 200 characters or so).
-
-
- 1 If you come across an internal error, we would appreciate it if you would contact
- Atari Technical Support and let us know about the problem.
-
-30 MADMAC Reference Manual
-\f
- Error Messages
-
-
-memory exhausted
- The assembler ran out of memory. You should (1) split up your source files
- and assemble them seperately, or (2) if you have any ramdisks or RAM-resident
- programs (like desk accessories) decrease their size so that the assembler has
- more RAM to work with. As a rule of thumb, pure 68000 code will use up to
- twice the number of bytes contained in the source files, whereas 6502 code will
- use 64K of ram right away, plus the size of the source files. The assembler itself
- uses about 80K bytes. Get out your calculator...
-
-too many ENDMs
-
- The assembler ran across an endm directive when it wasn't expecting to see
- one. The assembly is aborted. Check the nesting of your macro definitions -
- you probably have an extra endm.
-
-
-Errors
-
-
-.cargs syntax
- Syntax error in .cargs directive.
-
-.comm symbol already defined
- You tried to .comm a symbol that was already defined.
-
-.ds permitted only in BSS
- You tried to use .ds in the text or data section.
-
-.init not permitted in BSS or ABS
-
- You tried to use .init in the BSS or ABS section.
-
-.org permitted only in .6502 section
- You tried to use .org in a 68000 section.
-
-Cannot create: filename
- The assembler could not create the indicated filename.
-
-External quick reference
- You tried to make the immediate operand of a moveq, subq or addq instruc-
- tion external.
-
-
-PC-relative expr across sections
- You tried to make a PC-relative reference to a location contained in another
- section.
-
-[bwsl] must follow '.' in symbol
-
- You tried to follow a dot in a symbol name with something other than one of
- the four characters 'B', 'W', 'S' or 'L'.
-
-addressing mode syntax
-
- You made a syntax error in an addressing mode.
-
-assert failure
- One of your .assert directives failed!
-
-bad (section) expression
- You tried to mix and match sections in an expression
-
-bad 6502 addressing mode
- The 6502 mnemonic will not work with the addressing mode you specified.
-
-bad expression
- There's a syntax error in the expression you typed.
-
-
-
-
- MADMAC Reference Manual 31
-\f
- Error Messages
-
- bad size specified
- You tried to use an inappropriate size suffix for the instruction. Check your
- 68000 manual for allowable sizes.
- bad size suffix
- You can't use .b (byte) mode with the movem instruction.
- cannot .globl local symbol
- You tried to make a confined symbol global or common.
- cannot initialize non-storage (BSS) section
- You tried to generate instructions (or data, with dc) in the BSS or ABS section.
- cannot use '.b' with an address register
- You tried to use a byte-size suffix with an address register. The 68000 does not
- perform byte-sized address register operations.
- directive illegal in .6502 section
- You tried to use a 68000-oriented directive in the 6502 section.
- divide by zero
- The expression you typed involves a division by zero.
- expression out of range
- The expression you typed is out of range for its application.
- external byte reference
- You tried to make a byte-sized reference to an external symbol, which the
- object file format will not allow
- external short branch
- You tried to make a short branch to an external symbol, which the linker cannot
- handle.
- extra (unexpected) text found after addressing mode
- MADMAC thought it was done processing a line, but it ran up against "extra"
- stuff. Be sure that any comment on the line begins with a semicolon, and check
- for dangling commas, etc.
- forward or undefined .assert
- The expression you typed after a .assert directive had an undefined value.
- Remember that MADMAC is one-pass.
- hit EOF without finding matching .endif
- The assembler fell off the end of last input file without finding a . endif to
- match an . it. You probably forgot a . endif somewhere.
- illegal 6502 addressing mode
- The 6502 instruction you typed doesn't work with the addressing mode you
- specified.
- illegal absolute expression
- You can't use an absolute-valued expression here.
- illegal bra.s with zero offset
- You can't do a short branch to the very next instruction (read your 68000
- manual).
- illegal byte-sized relative reference
- The object file format does not permit bytes contain relocatable values; you
- tried to use a byte-sized relocatable expression in an immediate addressing
- mode.
-
- 32 MADMAC Reference Manual
-
-\f
- Error Messages
-
-illegal character
- Your source file contains a character that MADMAC doesn't allow. (most
- control characters fall into this category).
-illegal initialization of section
- You tried to use .dc or .dcb in the BSS or ABS sections.
-illegal relative address
- The relative address you specified is illegal because it belongs to a different
- section.
-illegal word relocatable (in .PRG mode)
- You can't have anything other than long relocatable values when you're gener-
- ating a .PRG file.
-inappropriate addressing mode
- The mnemonic you typed doesn't work with the addressing modes you specified.
- Check your 68000 manual for allowable combinations.
-invalid addressing mode
- The combination of addressing modes you picked for the movem instruction
- are not implemehydd by the 68000. Check your 68000 reference manual for
- details.
-invalid symbol following ^^
- What followed the ^^ wasn't a valid symbol at all.
-mis-nested .endr
- The assembler found a .endr directive when it wasn't prepared to find one.
- Check your repeat-block nesting.
-mismatched .else
- The assembler found a .else directive when it wasn't prepared to find one.
- Check your conditional assembly nesting.
-mismatched .endif
- The assembler found a .endif directive when it wasn't prepared to find one.
- Check your conditional assembly nesting.
-missing '='
-missing '}'
-missing argument name
-missing close parenthesis ')'
-missing close parenthesis ']'
-missing comma
-missing filename
-missing string
-missing symbol
-missing symbol or string
- The assembler expected to see a symbol/filename/string (etc...), but found
- something else instead. In most cases the problem should be obvious.
-misuse of '.', not allowed in symbols
- You tried to use a dot (.) in the middle of a symbol name.
-mod (%) by zero
- The expression you typed involves a modulo by zero.
-
-
-
-
- MADMAC Reference Man ual 33
-
-\f
- Error Messages
-
- multiple formal argument definition
- The list of formal parameter names you supplied for a macro definition includes
- two identical names.
- multiple macro definition
- You tried to define a macro which already had a definition.
- non-absolute byte reference
- You tried to make a byte reference to a relocatable value, which the object file
- format does not allow.
- non-absolute byte value
- You tried to dc.b or dcb.b a relocatable value. Byte relocatable values are
- not permitted by the object file format.
- register list order
- You tried to specify a register list like D7-D0, which is illegal. Remember
- that the first register number must be less than or equal to the second register
- number.
- register list syntax
- You made an error in specifying a register list for a .reg directive or a .movem
- instruction.
- symbol list syntax
- You probably forgot a comma between the names of two symbols in a symbol
- list, or you left a comma dangling on the end of the line.
- syntax error
- This is a "catch-all" error.
- undefined expression
- The expression has an undefined value because of a forward reference, or an
- undefined or external symbol.
- unimplemented addressing mode
- You tried to use 68020 "square-bracket" notation for a 68020 addressing mode.
- MADMAC does not support 68020 addressing modes.
- unimplemented directive
- You have found a directive that didn't appear in the documentation. It doesn't
- work.
- unimplemented mnemonic
- You've found an assembler for documentation) bug.
- unknown symbol following ^^
- You followed a ^^ with something other than one of the names defined, ref-
- erenced or streq.
- unsupported 68020 addressing mode
- The assembler saw a 68020-type addressing mode. MADMAC does not assem-
- ble code for the 68020 or 68010.
- unterminated string
- You specified a string starting with a single or double quote, but forgot to type
- the closing quote.
- write error
- The assembler had a problem writing an object file. This is usually caused by
- a full disk, or a bad sector on the media.
-
-34 MADMAC Reference Manual
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-\f
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-\f
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