13 *NOTE: Every effort has been made to ensure the accuracy and robustness of this
14 manual and the associated software. However, because Reboot is constantly improving
15 and updating its computer software, it is unable to guarantee
16 the accuracy of printed or duplicated material after the date of publication and
17 disclaims liability for changes, errors or omissions.*
20 *Copyright © 2011-2017, Reboot*
22 *All rights reserved.*
24 *Reboot Document number F00000K-001 Rev. A.*
36 This document describes RMAC, a fast macro assembler for the 68000. RMAC currently
37 runs on the any POSIX compatible platform and the Atari ST. It was initially written
38 at Atari Corporation by programmers who needed a high performance assembler
39 for their work. Then, more than 20 years later, because there was still a need for
40 such an assembler and what was available wasn't up to expectations, Subqmod
41 and eventually Reboot continued work on the freely released source, adding Jaguar extensions
44 RMAC is intended to be used by programmers who write mostly in assembly language.
45 It was not originally a back-end to a C compiler, therefore it
46 has creature comfort that are usually neglected in such back-end assemblers. It
47 supports include files, macros, symbols with limited scope, some limited control
48 structures, and other features. RMAC is also blindingly fast, another feature
49 often sadly and obviously missing in today's assemblers.\ [1]_
51 RMAC is not entirely compatible with the AS68 assembler provided with
52 the original Atari ST Developer's Kit, but most changes are minor and a few minutes
53 with an editor should allow you to assemble your current source files. If you are an
54 AS68 user, before you leap into the unknown please read the section on Notes for
57 .. [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!
63 * The distribution disk contains a file called README that you should read.
64 This file contains important nays about the contents of the distribution disk
65 and summarizes the most recent changes to the tools.
67 * Hard disk users can simply copy the executable files to their work or binary
68 directories. People with floppy disks can copy the executables to ramdisks,
69 install the assembler with the -q option, or even work right off of the floppies.
71 * You will need an editor that can produce "normal" format text files. Micro
72 Emacs will work well, as will most other commercial program editors, but not
73 most word processors (such as First Word or Microsoft Write).
75 * You will probably want to examine or get a listing of the file "ATARI.S". It
76 contains lots of definitions for the Atari ST, including BIOS variables, most
77 BIOS, XBIOS and GEMDOS traps, and line-A equates. We (or you) could
78 split the file up into pieces (a file for line-A equates, a file for hardware and
79 BIOS variables and so on), but RMAC is so fast that it doesn't matter
82 * Read the rest of the manual, especially the first two chapters on The Command Line and Using RMAC.
83 Also, `Notes for migrating from other 68000 assemblers`_ will save a lot of time and frustration in the long run.
84 The distribution disk contains example
85 programs that you can look at, assemble and modify.
90 The assembler is called "**rmac**" or "**rmac.prg**". The command line takes the form:
92 **rmac** [*switches*] [*files* ...]
94 A command line consists of any number of switches followed by the names of files
95 to assemble. A switch is specified with a dash (**-**) followed immediately by a key
96 character. Key characters are not case-sensitive, so "**-d**" is the same as "**-D**". Some
97 switches accept (or require) arguments to immediately follow the key character,
98 with no spaces in between.
100 Switch order is important. Command lines are processed from left to right in
101 one pass, and switches usually take effect when they are encountered. In general it
102 is best to specify all switches before the names of any input files.
104 If the command line is entirely empty then RMAC prints a copyright message
105 along with usage info and exit.
107 Input files are assumed to have the extension "**.s**"; if a filename has no extension
108 (i.e. no dot) then "**.s**" will be appended to it. More than one source filename may be
109 specified: the files are assembled into one object file, as if they were concatenated.
111 RMAC normally produces object code in "**file.o**" if "**file.s**" is the first
112 input filename. If the first input file is a special character device, the output name
113 is noname.o. The **-o** switch (see below) can be used change the output file name.
116 =================== ===========
118 =================== ===========
119 -dname\ *[=value]* Define symbol, with optional value.
120 -e\ *[file[.err]]* Direct error messages to the specified file.
121 -fa ALCYON output object file format (implied with **-ps** is enabled).
122 -fb BSD COFF output object file format.
123 -fe ELF output object file format.
124 -fx Atari 800 com/exe/xex output object file format.
125 -i\ *path* Set include-file directory search path.
126 -l\ *[file[prn]]* Construct and direct assembly listing to the specified file.
127 -l\ *\*[filename]* Create an output listing file without pagination
128 -o\ *file[.o]* Direct object code output to the specified file.
129 +/~oall Turn all optimisations on/off
130 +o\ *0-3* Enable specific optimisation
131 ~o\ *0-3* Disable specific optimisation
133 `0: Absolute long adddresses to word`
135 `1: move.l #x,dn/an to moveq`
137 `2: Word branches to short
139 `3: Outer displacement 0(an) to (an)`
140 -p Produce an executable (**.prg**) output file.
141 -ps Produce an executable (**.prg**) output file with symbols.
142 -q Make RMAC resident in memory (Atari ST only).
143 -r *size* automatically pad the size of each
144 segment in the output file until the size is an integral multiple of the
145 specified boundary. Size is a letter that specifies the desired boundary.
147 `-rw Word (2 bytes, default alignment)`
151 `-rp Phrase (8 bytes)`
153 `-rd Double Phrase (16 bytes)`
155 `-rq Quad Phrase (32 bytes)`
156 -s Warn about unoptimized long branches and applied optimisations.
157 -u Force referenced and undefined symbols global.
158 -v Verbose mode (print running dialogue).
159 -x Turn on debugging mode
160 -yn Set listing page size to n lines.
161 file\ *[s]* Assemble the specified file.
162 =================== ===========
164 The switches are described below. A summary of all the switches is given in
168 The **-d** switch permits symbols to be defined on the command line. The name
169 of the symbol to be defined immediately follows the switch (no spaces). The
170 symbol name may optionally be followed by an equals sign (=) and a decimal
171 number. If no value is specified the symbol's value is zero. The symbol at-
172 tributes are "defined, not referenced, and absolute". This switch is most useful
173 for enabling conditionally-assembled debugging code on the command line; for
178 -dDEBUG -dLoopCount=999 -dDebugLevel=55
181 The -e switch causes RMAC to send error messages to a file, instead of the
182 console. If a filename immediately follows the switch character, error messages
183 are written to the specified file. If no filename is specified, a file is created with
184 the default extension "**.err**" and with the root name taken from the first input
185 file name (e.g. error messages are written to "**file.err**" if "**file**" or "**file.s**" is
186 the first input file name). If no errors are encountered, then no error listing
187 file is created. Beware! If an assembly produces no errors, any error file from
188 a previous assembly is not removed.
191 The **-i** switch allows automatic directory searching for include files. A list of
192 semi-colon seperated directory search paths may be mentioned immediately
193 following the switch (with no spaces anywhere). For example:
197 -im:;c:include;c:include\sys
199 will cause the assembler to search the current directory of device **M**, and the
200 directories include and include\sys on drive **C**. If *-i* is not specified, and the
201 enviroment variable "**RMACPATH**" exists, its value is used in the same manner.
202 For example, users of the Mark Williams shell could put the following line in
203 their profile script to achieve the same result as the **-i** example above:
207 setenv RMACPATH="m:;c:include;c:include\sys"
209 The -l switch causes RMAC to generate an assembly listing file. If a file-
210 name immediately follows the switch character, the listing is written to the
211 specified file. If no filename is specified, then a listing file is created with the
212 default extension "**.prn**" and with the root name taken from the first input file
213 name (e.g. the listing is written to "**file.prn**" if "**file**" or "**file.s**" is the first
216 The -o switch causes RMAC to write object code on the specified file. No
217 default extension is applied to the filename. For historical reasons the filename
218 can also be seperated from the switch with a space (e.g. "**-o file**").
223 The **-p** and **-ps** switches cause RMAC to produce an Atari ST executable
224 file with the default extension of "**.prg**". If there are any external references
225 at the end of the assembly, an error message is emitted and no executable file
226 is generated. The **-p** switch does not write symbols to the executable file. The
227 **-ps** switch includes symbols (Alcyon format) in the executable file.
229 The **-q** switch is aimed primarily at users of floppy-disk-only systems. It causes
230 RMAC to install itself in memory, like a RAMdisk. Then the program
231 **m.prg** (which is very short - less than a sector) can be used instead of
232 **mac.prg**, which can take ten or twelve seconds to load. (**NOTE** not available
233 for now, might be re-implemented in the future).
235 The **-s** switch causes RMAC to generate a list of unoptimized forward
236 branches as warning messages. This is used to point out branches that could
237 have been short (e.g. "bra" could be "bra.s").
239 The **-u** switch takes effect at the end of the assembly. It forces all referenced
240 and undefined symbols to be global, exactly as if they had been made global
241 with a **.extern** or **.globl** directive. This can be used if you have a lot of
242 external symbols, and you don't feel like declaring them all external.
244 The **-v** switch turns on a "verbose" mode in which RMAC prints out (for
245 example) the names of the files it is currently processing. Verbose mode is
246 automatically entered when RMAC prompts for input with a star.
248 The **-y** switch, followed immediately by a decimal number (with no intervening
249 space), sets the number of lines in a page. RMAC will produce *N* lines
250 before emitting a form-feed. If *N* is missing or less than 10 an error message is
256 Let's assemble and link some example programs. These programs are included
257 on the distribution disk in the "**EXAMPLES**" directory - you should copy them to
258 your work area before continuing. In the following examples we adopt the conven-
259 tions that the shell prompt is a percent sign (%) and that your input (the stuff you
260 type) is presented in **bold face**.
262 If you have been reading carefully, you know that RMAC can generate
263 an executable file without linking. This is useful for making small, stand alone
264 programs that don't require externals or library routines. For example, the following
272 could be replaced by the single command:
278 since you don't need the linker for stand-alone object files.
280 Successive source files named in the command line are are concatenated, as in
281 this example, which assembles three files into a single executable, as if they were
286 % rmac -p bugs shift images
288 Of course you can get the same effect by using the **.include** directive, but sometimes
289 it is convenient to do the concatenation from the command line.
291 Here we have an unbelievably complex command line:
295 % rmac -lzorf -y95 -o tmp -ehack -Ddebug=123 -ps example
297 This produces a listing on the file called "**zorf.prn**" with 95 lines per page, writes
298 the executable code (with symbols) to a file called "**tmp.prg**", writes an error listing
299 to the file "**hack.err**", specifies an include-file path that includes the current
300 directory on the drive "**M:**," defines the symbol "**debug**" to have the value 123, and
301 assembles the file "**example.s**". (Take a deep breath - you got all that?)
303 One last thing. If there are any assembly errors, RMAC will terminate
304 with an exit code of 1. If the assembly succeeds (no errors, although there may be
305 warnings) the exit code will be 0. This is primarily for use with "make" utilities.
307 Things You Should Be Aware Of
308 '''''''''''''''''''''''''''''
309 RMAC is a one pass assembler. This means that it gets all of its work done by
310 reading each source file exactly once and then "back-patching" to fix up forward
311 references. This one-pass nature is usually transparent to the programmer, with
312 the following important exceptions:
314 * In listings, the object code for forward references is not shown. Instead, lower-
315 case "xx"s are displayed for each undefined byte, as in the following example:
319 60xx 1: bra.s.2 ;forward branch
320 xxxxxxxx dc.l .2 ;forward reference
321 60FE .2: bra.s.2 ;backward reference
323 * Forward branches (including **BSR**\s) are never optimized to their short forms.
324 To get a short forward branch it is necessary to explicitly use the ".s" suffix in
326 * Error messages may appear at the end of the assembly, referring to earlier source
327 lines that contained undefined symbols.
328 * All object code generated must fit in memory. Running out of memory is a
329 fatal error that you must deal with by splitting up your source files, re-sizing
330 or eliminating memory-using programs such as ramdisks and desk accessories,
335 RMAC does not optimize forward branches for you, but it will tell you about
336 them if you use the -s (short branch) option:
341 "example.s", line 20: warning: unoptimized short branch
343 With the -e option you can redirect the error output to a file, and determine by
344 hand (or editor macros) which forward branches are safe to explicitly declare short.
346 `Notes for migrating from other 68000 assemblers`_
347 ''''''''''''''''''''''''''''''''''''''''''''''''''
348 RMAC is not entirely compatible with the other popular assemblers
349 like Devpac or vasm. This section
350 outlines the major differences. In practice, we have found that very few changes are
351 necessary to make other assemblers' source code assemble.
353 * A semicolon (;) must be used to introduce a comment,
354 except that a star (*)
355 may be used in the first column. AS68 treated anything following the operand
356 field, preceeded by whitespace, as a comment. (RMAC treats a star that
357 is not in column 1 as a multiplication operator).
358 * Labels require colons (even labels that begin in column 1).
360 * Conditional assembly directives are called **if**, **else** and **endif**.
361 Devpac and vasm called these
362 **ifne**, **ifeq** (etc.), and **endc**.
363 * The tilde (~) character is an operator, and back-quote (`) is an illegal character.
364 AS68 permitted the tilde and back-quote characters in symbols.
365 * There are no equivalents to org or section directives.
366 The **.xdef** and **.xref** directives are not implemented,
367 but **.globl** makes these unnecessary anyway.
369 * The location counter cannot be manipulated with a statement of the form:
375 * The **ds** directive is not permitted in the text or data segments;
376 an error message is issued. Use **dcb** instead to reserve large blocks of
378 * Back-slashes in strings are "electric" characters that are used to escape C-like
379 character codes. Watch out for GEMDOS path names in ASCII constants -
380 you will have to convert them to double-backslashes.
381 * Expression evaluation is done left-to-right without operator precedence. Use parentheses to
382 force the expression evaluation as you wish.
383 * Mark your segments across files.
384 Branching to a code segment that could be identified as BSS will cause a "Error: cannot initialize non-storage (BSS) section"
385 * rs.b/rs.w/rs.l/rscount/rsreset can be simulated in rmac using abs.
386 For example the following source:
396 size_so_far equ rscount
408 size_so_far equ ^^abscount
409 * A rare case: if your macro contains something like:
419 then by the assembler's design this will fail as the parameters are automatically converted to hex. Changing the code like this works:
431 For those using editors other than the "Emacs" style ones (Micro-Emacs, Mince,
432 etc.) this section documents the source file format that RMAC expects.
434 * Files must contain characters with ASCII values less than 128; it is not per-
435 missable to have characters with their high bits set unless those characters are
436 contained in strings (i.e. between single or double quotes) or in comments.
438 * Lines of text are terminated with carriage-return/line-feed, linefeed alone, or
439 carriage-return alone.
441 * The file is assumed to end with the last terminated line. If there is text beyond
442 the last line terminator (e.g. control-Z) it is ignored.
449 A statement may contain up to four fields which are identified by order of ap-
450 pearance and terminating characters. The general form of an assembler statement
455 label: operator operand(s) ; comment
457 The label and comment fields are optional. An operand field may not appear
458 without an operator field. Operands are seperated with commas. Blank lines are
459 legal. If the first character on a line is an asterisk (*) or semicolon (;) then the
460 entire line is a comment. A semicolon anywhere on the line (except in a string)
461 begins a comment field which extends to the end of the line.
463 The label, if it appears, must be terminated with a single or double colon. If
464 it is terminated with a double colon it is automatically declared global. It is illegal
465 to declare a confined symbol global (see: `Symbols and Scope`_).
469 A statement may also take one of these special forms:
471 *symbol* **equ** *expression*
473 *symbol* **=** *expression*
475 *symbol* **==** *expression*
477 *symbol* **set** *expression*
479 *symbol* **reg** *register list*
481 The first two forms are identical; they equate the symbol to the value of an
482 expression, which must be defined (no forward references). The third form, double-
483 equals (==), is just like an equate except that it also makes the symbol global. (As
484 with labels, it is illegal to make a confined equate global.) The fourth form allows
485 a symbol to be set to a value any number of times, like a variable. The last form
486 equates the symbol to a 16-bit register mask specified by a register list. It is possible
487 to equate confined symbols (see: `Symbols and Scope`_). For example:
491 cr equ 13 carriage-return
493 DEBUG == 1 global debug flag
495 count set count + 1 increment variable
496 .rags reg d3-d7/a3-a6 register list
497 .cr 13 confined equate
501 Symbols may start with an uppercase or lowercase letter (A-Z a-z), an underscore
502 (**_**), a question mark (**?**) or a period (**.**). Each remaining character may be an
503 upper or lowercase letter, a digit (**0-9**), an underscore, a dollar sign (**$**), or a question
504 mark. (Periods can only begin a symbol, they cannot appear as a symbol
505 continuation character). Symbols are terminated with a character that is not a
506 symbol continuation character (e.g. a period or comma, whitespace, etc.). Case is
507 significant for user-defined symbols, but not for 68000 mnemonics, assembler direc-
508 tives and register names. Symbols are limited to 100 characters. When symbols
509 are written to the object file they are silently truncated to eight (or sixteen) char-
510 acters (depending on the object file format) with no check for (or warnings about)
513 For example, all of the following symbols are legal and unique:
517 reallyLongSymbolName .reallyLongConfinedSymbolName
518 a10 ret move dc frog aa6 a9 ????
519 .a1 .ret .move .dc .frog .a9 .9 ????
520 .0 .00 .000 .1 .11. .111 . ._
521 _frog ?zippo? sys$syetem atari Atari ATARI aTaRi
523 while all of the following symbols are illegal:
527 12days dc.10 dc.z 'quote .right.here
528 @work hi.there $money$ ~tilde
531 Symbols beginning with a period (**.**) are *confined*; their scope is between two
532 normal (unconfined) labels. Confined symbols may be labels or equates. It is illegal
533 to make a confined symbol global (with the ".globl" directive, a double colon, or a
534 double equals). Only unconfined labels delimit a confined symbol's scope; equates
535 (of any kind) do not count. For example, all symbols are unique and have unique
536 values in the following:
547 .loop: move.w -1,(a0)+
551 Confined symbols are useful since the programmer has to be much less inventive
552 about finding small, unique names that also have meaning.
554 It is legal to define symbols that have the same names as processor mnemonics
555 (such as "**move**" or "**rts**") or assembler directives (such as "**.even**"). Indeed, one
556 should be careful to avoid typographical errors, such as this classic (in 6502 mode):
564 which equates a confined symbol to a hexadecimal value, rather than setting the
565 location counter, which the .org directive does (without the equals sign).
569 The following names, in all combinations of uppercase and lowercase, are keywords
570 and may not be used as symbols (e.g. labels, equates, or the names of macros):
576 d0 d1 d2 d3 d4 d5 d6 d7
577 a0 a1 a2 a3 a4 a5 a6 a7
578 r0 r1 r2 r3 r4 r5 r6 r7
579 r8 r9 r10 r11 r12 rl3 r14 ri5
583 Numbers may be decimal, hexadecimal, octal, binary or concatenated ASCII. The
584 default radix is decimal, and it may not be changed. Decimal numbers are specified
585 with a string of digits (**0-9**). Hexadecimal numbers are specified with a leading
586 dollar sign (**$**) followed by a string of digits and uppercase or lowercase letters (**A-F
587 a-f**). Octal numbers are specified with a leading at-sign (**@**) followed by a string
588 of octal digits (**0-7**). Binary numbers are specified with a leading percent sign
589 (**%**) followed by a string of binary digits (**0-1**). Concatenated ASCII constants are
590 specified by enclosing from one to four characters in single or double quotes. For
602 Negative numbers Are specified with a unary minus (**-**). For example:
611 Strings are contained between double (") or single ( ') quote marks. Strings may
612 contain non-printable characters by specifying "backslash" escapes, similar to the
613 ones used in the C programming language. RMAC will generate a warning if a
614 backslash is followed by a character not appearing below:
619 \n $0a line-feed (newline)
622 \r $0c1 carriage-return
628 It is possible for strings (but not symbols) to contain characters with their high
629 bits set (i.e. character codes 128...255).
631 You should be aware that backslash characters are popular in GEMDOS path
632 names, and that you may have to escape backslash characters in your existing source
633 code. For example, to get the file "'c:\\auto\\ahdi.s'" you would specify the string
634 "`c:\\\\auto\\\\ahdi.s`".
638 Register lists are special forms used with the **movem** mnemonic and the **.reg**
639 directive. They are 16-bit values, with bits 0 through 15 corresponding to registers
640 **D0** through **A7**. A register list consists of a series of register names or register
641 ranges seperated by slashes. A register range consists of two register names, Rm
642 and Rn,m<n, seperated by a dash. For example:
650 d0/d1/a0-a3/d7/a6-a7 $CF83
654 Register lists and register equates may be used in conjunction with the movem
655 mnemonic, as in this example:
659 temps reg d0-d2/a0-a2 ; temp registers
660 keeps reg d3-d7/d3-a6 ; registers to preserve
661 allregs reg d0-d7/a0-a7 ; all registers
662 movem.l #temps,-(sp) ; these two lines ...
663 movem.l d0-d2/a0-a2,-(sp) ; are identical
664 movem.l #keeps,-(sp) ; save "keep" registers
665 movem.l (sp)+,#keeps ; restore "keep" registers
670 `Order of Evaluation`_
671 ''''''''''''''''''''''
672 All values are computed with 32-bit 2's complement arithmetic. For boolean operations
673 (such as if or **assert**) zero is considered false, and non-zero is considered
676 **Expressions are evaluated strictly left-to-right, with no
677 regard for operator precedence.**
679 Thus the expression "1+2*3" evaluates to 9, not 7. However, precedence may be
680 forced with parenthesis (**()**) or square-brackets (**[]**).
684 Expressions belong to one of three classes: undefined, absolute or relocatable. An
685 expression is undefined if it involves an undefined symbol (e.g. an undeclared sym-
686 bol, or a forward reference). An expression is absolute if its value will not change
687 when the program is relocated (for instance, the number 0, all labels declared in
688 an abs section, and all Atari ST hardware register locations are absolute values).
689 An expression is relocatable if it involves exactly one symbol that is contained in a
690 text, data or BSS section.
692 Only absolute values may be used with operators other than addition (+) or
693 subtraction (-). It is illegal, for instance, to multiply or divide by a relocatable or
694 undefined value. Subtracting a relocatable value from another relocatable value in
695 the same section results in an absolute value (the distance between them, positive
696 or negative). Adding (or subtracting) an absolute value to or from a relocatable
697 value yeilds a relocatable value (an offset from the relocatable address).
699 It is important to realize that relocatable values belong to the sections they
700 are defined in (e.g. text, data or BSS), and it is not permissible to mix and match
701 sections. For example, in this code:
705 linel: dc.l line2, line1+8
706 line2: dc.l line1, line2-8
707 line3: dc.l line2-line1, 8
708 error: dc.l line1+line2, line2 >> 1, line3/4
710 Line 1 deposits two longwords that point to line 2. Line 2 deposits two longwords
711 that point to line 1. Line 3 deposits two longwords that have the absolute value
712 eight. The fourth line will result in an assembly error, since the expressions (re-
713 spectively) attempt to add two relocatable values, shift a relocatable value right by
714 one, and divide a relocatable value by four.
716 The pseudo-symbol "*****" (star) has the value that the current section's location
717 counter had at the beginning of the current source line. For example, these two
718 statements deposit three pointers to the label "**bar**":
725 Similarly, the pseudo-symbol "**$**" has the value that the current section's location
726 counter has, and it is kept up to date as the assembler deposits information
727 "across" a line of source code. For example, these two statements deposit four
728 pointers to the label "zip":
738 ================================ ========================================
740 ================================ ========================================
741 **-** Unary minus (2's complement).
742 **!** Logical (boolean) NOT.
743 **~** Tilde: bitwise not (l's complement).
744 **^^defined** *symbol* True if symbol has a value.
745 **^^referenced** *symbol* True if symbol has been referenced.
746 **^^streq** *stringl*,*string2* True if the strings are equal.
747 **^^macdef** *macroName* True if the macro is defined.
748 **^^abscount** Returns the size of current .abs section
749 ================================ ========================================
751 * The boolean operators generate the value 1 if the expression is true, and 0 if it is not.
753 * A symbol is referenced if it is involved in an expression.
755 any combination of attributes: undefined and unreferenced, defined and unref-
756 erenced (i.e. declared but never used), undefined and referenced (in the case
757 of a forward or external reference), or defined and referenced.
764 =========== ==============================================
766 =========== ==============================================
767 \ + - * / The usual arithmetic operators.
768 % Modulo. Do *not* attempt to modulo by 0 or 1.
769 & | ^ Bit-wise **AND**, **OR** and **Exclusive-OR**.
770 << >> Bit-wise shift left and shift right.
771 < <= >= > Boolean magnitude comparisons.
773 <> != Boolean inequality.
774 =========== ==============================================
776 * All binary operators have the same precedence:
777 expressions are evaluated strictly left to right.
779 * Division or modulo by zero yields an assembly error.
781 * The "<>" and "!=" operators are synonyms.
783 * Note that the modulo operator (%) is also used to introduce binary constants
784 (see: `Constants`_). A percent sign should be followed by at least one space if
785 it is meant to be a modulo operator, and is followed by a '0' or '1'.
790 ============ =========================================
791 Special Form Description
792 ============ =========================================
793 **^^date** The current system date (Gemdos format).
794 **^^time** The current system time (Gemdos format).
795 ============ =========================================
797 * The "**^^date**" special form expands to the current system date, in Gemdos
798 format. The format is a 16-bit word with bits 0 ...4 indicating the day of the
799 month (1...31), bits 5...8 indicating the month (1...12), and bits 9...15
800 indicating the year since 1980, in the range 0...119.
802 * The "**^^time**" special form expands to the current system time, in Gemdos
803 format. The format is a 16-bit word with bits 0...4 indicating the current
804 second divided by 2, bits 5...10 indicating the current minute 0...59. and
805 bits 11...15 indicating the current hour 0...23.
807 `Example Expressions`_
808 ''''''''''''''''''''''
812 line address contents source code
813 ---- ------- -------- -------------------------------
814 1 00000000 4480 lab1: neg.l d0
815 2 00000002 427900000000 lab2: clr.w lab1
816 3 =00000064 equ1 = 100
817 4 =00000096 equ2 = equ1 + 50
818 5 00000008 00000064 dc.l lab1 + equ1
819 6 0000000C 7FFFFFE6 dc.l (equl + ~equ2) >> 1
820 7 00000010 0001 dc.w ^^defined equl
821 8 00000012 0000 dc.w ^^referenced lab2
822 9 00000014 00000002 dc.l lab2
823 10 00000018 0001 dc.w ^^referenced lab2
824 11 0000001A 0001 dc.w lab1 = (lab2 - 6)
826 Lines 1 through four here are used to set up the rest of the example. Line 5 deposits
827 a relocatable pointer to the location 100 bytes beyond the label "**lab1**". Line 6 is
828 a nonsensical expression that uses the and right-shift operators. Line 7 deposits
829 a word of 1 because the symbol "**equ1**" is defined (in line 3).
831 Line 8 deposits a word of 0 because the symbol "**lab2**", defined in line 2, has
832 not been referenced. But the expression in line 9 references the symbol "**lab2**", so
833 line 10 (which is a copy of line-8) deposits a word of 1. Finally, line 11 deposits a
834 word of 1 because the Boolean equality operator evaluates to true.
836 The operators "**^^defined**" and "**^^referenced**" are particularly useful in
837 conditional assembly. For instance, it is possible to automatically include debugging
838 code if the debugging code is referenced, as in:
842 lea string,a0 ; AO -> message
843 jsr debug ; print a message
845 string: dc.b "Help me, Spock!",0 ; (the message)
849 .iif ^^defined debug, .include "debug.s"
851 The **jsr** statement references the symbol debug. Near the end of the source file, the
852 "**.iif**" statement includes the file "**debug.s**" if the symbol debug was referenced.
854 In production code, presumably all references to the debug symbol will be removed,
855 and the debug source file will not be included. (We could have as easily made the
856 symbol **debug** external, instead of including another source file).
862 Assembler directives may be any mix of upper- or lowercase. The leading periods
863 are optional, though they are shown here and their use is encouraged. Directives
864 may be preceeded by a label; the label is defined before the directive is executed.
865 Some directives accept size suffixes (**.b**, **.s**, **.w** or **.1**); the default is word (**.w**) if no
866 size is specified. The **.s** suffix is identical to **.b**. Directives relating to the 6502 are
867 described in the chapter on `6502 Support`_.
873 If the location counter for the current section is odd, make it even by adding
874 one to it. In text and data sections a zero byte is deposited if necessary.
877 Align the program counter to the next integral long boundary (4 bytes).
878 Note that GPU/DSP code sections are not contained in their own
879 segments and are actually part of the TEXT or DATA segments.
880 Therefore, to align GPU/DSP code, align the current section before and
881 after the GPU/DSP code.
884 Align the program counter to the next integral phrase boundary (8 bytes).
885 Note that GPU/DSP code sections are not contained in their own
886 segments and are actually part of the TEXT or DATA segments.
887 Therefore, to align GPU/DSP code, align the current section before and
888 after the GPU/DSP code.
891 Align the program counter to the next integral double phrase boundary (16
892 bytes). Note that GPU/DSP code sections are not contained in their own
893 segments and are actually part of the TEXT or DATA segments.
894 Therefore, to align GPU/DSP code, align the current section before and
895 after the GPU/DSP code.
898 Align the program counter to the next integral quad phrase boundary (32
899 bytes). Note that GPU/DSP code sections are not contained in their own
900 segments and are actually part of the TEXT or DATA segments.
901 Therefore, to align GPU/DSP code, align the current section before and
902 after the GPU/DSP code.
903 **.assert** *expression* [,\ *expression*...]
905 Assert that the conditions are true (non-zero). If any of the comma-seperated
906 expressions evaluates to zero an assembler warning is issued. For example:
910 .assert *-start = $76
911 .assert stacksize >= $400
919 Switch to the BSS, data or text segments. Instructions and data may not
920 be assembled into the BSS-segment, but symbols may be defined and storage
921 may be reserved with the **.ds** directive. Each assembly starts out in the text
923 **.abs** [*location*]
925 Start an absolute section, beginning with the specified location (or zero, if
926 no location is specified). An absolute section is much like BSS, except that
927 locations declared with .ds are based absolute. This directive is useful for
929 declaring structures or hardware locations.
930 For example, the following equates:
940 could be as easily defined as:
951 Another interesting example worth mentioning is the emulation of "C"'s "union" keyword
952 using *.abs*. For example, the following "C" code:
962 union { int spf_em_colour; int spf_emx_colour; };
963 union { int spf_em_psmask[16]; int spf_emx_colouropt; };
971 *-------------------------------------------------------*
972 spf_w: ds.w 1 ;<- common
977 *-------------------------------------------------------*
979 spf_em_colour: ds.l 1 ;<- union #1
980 spf_em_psmask: ds.l 16
981 *-------------------------------------------------------*
985 spf_emx_colour: ds.l 1 ;<- union #2
986 spf_emx_colouropt: ds.l 1
987 spf_emx_psmask: ds.l 16
988 spf_emx_psmaskopt: ds.l 16
991 ;*-------------------------------------------------------*
993 move #spf_em_colour,d0
994 move #spf_emx_colour,d0
996 In this example, *spf_em_colour* and *spf_emx_colour* will have the same value.
998 **.comm** *symbol*, *expression*
1000 Specifies a label and the size of a common region. The label is made global,
1001 thus confined symbols cannot be made common. The linker groups all common
1002 regions of the same name; the largest size determines the real size of the
1003 common region when the file is linked.
1004 **.ccdef** *expression*
1006 Allows you to define names for the condition codes used by the JUMP
1007 and JR instructions for GPU and DSP code. For example:
1013 jump Always,(r3) ; ‘Always’ is actually 0
1015 **.ccundef** *regname*
1017 Undefines a register name (regname) previously assigned using the
1018 .CCDEF directive. This is only implemented in GPU and DSP code
1020 **.dc.i** *expression*
1022 This directive generates long data values and is similar to the DC.L
1023 directive, except the high and low words are swapped. This is provided
1024 for use with the GPU/DSP MOVEI instruction.
1025 **.dc**\ [.\ *size*] *expression* [, *expression*...]
1027 Deposit initialized storage in the current section. If the specified size is word
1028 or long, the assembler will execute a .even before depositing data. If the size
1029 is .b, then strings that are not part of arithmetic expressions are deposited
1030 byte-by-byte. If no size is specified, the default is .w. This directive cannot be
1031 used in the BSS section.
1032 **.dcb**\ [.\ *size*] *expression1*, *expression2*
1034 Generate an initialized block of *expression1* bytes, words or longwords of the
1035 value *expression2*. If the specified size is word or long, the assembler will
1036 execute .even before generating data. If no size is specified, the default is **.w**.
1037 This directive cannot be used in the BSS section.
1038 **.ds**\ [.\ *size*] *expression*
1040 Reserve space in the current segment for the appropriate number of bytes,
1041 words or longwords. If no size is specified, the default size is .w. If the size
1042 is word or long, the assembler will execute .even before reserving space.
1045 Switch to Jaguar DSP assembly mode. This directive must be used
1046 within the TEXT or DATA segments.
1047 **.init**\ [.\ *size*] [#\ *expression*,]\ *expression*\ [.\ *size*] [,...]
1049 Generalized initialization directive. The size specified on the directive becomes
1050 the default size for the rest of the line. (The "default" default size is **.w**.) A
1051 comma-seperated list of expressions follows the directive; an expression may be
1052 followed by a size to override the default size. An expression may be preceeded
1053 by a sharp sign, an expression and a comma, which specifies a repeat count to
1054 be applied to the next expression. For example:
1058 .init.l -1, 0.w, #16,'z'.b, #3,0, 11.b
1060 will deposit a longword of -1, a word of zero, sixteen bytes of lower-case 'z',
1061 three longwords of zero, and a byte of 11.
1063 No auto-alignment is performed within the line, but a **.even** is done once
1064 (before the first value is deposited) if the default size is word or long.
1065 **.cargs** [#\ *expression*,] *symbol*\ [.\ *size*] [, *symbol*\ [.\ *size*].. .]
1067 Compute stack offsets to C (and other language) arguments. Each symbol is
1068 assigned an absolute value (like equ) which starts at expression and increases
1069 by the size of each symbol, for each symbol. If the expression is not supplied,
1070 the default starting value is 4. For example:
1074 .cargs #8, .fileliams.1, .openMode, .butPointer.l
1076 could be used to declare offsets from A6 to a pointer to a filename, a word
1077 containing an open mode, and a pointer to a buffer. (Note that the symbols
1078 used here are confined). Another example, a C-style "string-length" function,
1079 could be written as:
1083 _strlen:: .cargs .string ; declare arg
1084 move.l .string(sp),a0 ; a0 -> string
1085 moveq #-1,d0 ; initial size = -1
1086 .1: addq.1 #1,d0 ; bump size
1087 tst.b (a0)+ ; at end of string?
1088 bne .1 ; (no -- try again)
1089 rts ; return string length
1093 End the assembly. In an include file, end the include file and resume assembling
1094 the superior file. This statement is not required, nor are warning messages
1095 generated if it is missing at the end of a file. This directive may be used inside
1096 conditional assembly, macros or **.rept** blocks.
1097 **.equr** *expression*
1099 Allows you to name a register. This is only implemented for GPU/DSP
1100 code sections. For example:
1106 add ClipW,r0 ; ClipW actually is r19
1108 **.if** *expression*
1114 Start a block of conditional assembly. If the expression is true (non-zero) then
1115 assemble the statements between the .if and the matching **.endif** or **.else**.
1116 If the expression is false, ignore the statements unless a matching .else is
1117 encountered. Conditional assembly may be nested to any depth.
1119 It is possible to exit a conditional assembly block early from within an include
1120 file (with **end**) or a macro (with **endm**).
1122 **.iif** *expression*, *statement*
1124 Immediate version of **.if**. If the expression is true (non-zero) then the state-
1125 ment, which may be an instruction, a directive or a macro, is executed. If
1126 the expression is false, the statement is ignored. No **.endif** is required. For
1131 .iif age < 21, canDrink = 0
1132 .iif weight > 500, dangerFlag = 1
1133 .iif !(^^defined DEBUG), .include dbsrc
1135 **.macro** *name* [*formal*, *formal*,...]
1141 Define a macro called name with the specified formal arguments. The macro
1142 definition is terminated with a **.endm** statement. A macro may be exited early
1143 with the .exitm directive. See the chapter on `Macros`_ for more information.
1145 **.undefmac** *macroName* [, *macroName*...]
1147 Remove the macro-definition for the specified macro names. If reference is
1148 made to a macro that is not defined, no error message is printed and the name
1151 **.rept** *expression*
1155 The statements between the **.rept** and **.endr** directives will be repeated *expression*
1156 times. If the expression is zero or negative, no statements will be
1157 assembled. No label may appear on a line containing either of these directives.
1159 **.globl** *symbol* [, *symbol*...]
1161 **.extern** *symbol* [, *symbol*...]
1163 Each symbol is made global. None of the symbols may be confined symbols
1164 (those starting with a period). If the symbol is defined in the assembly, the
1165 symbol is exported in the object file. If the symbol is undefined at the end
1166 of the assembly, and it was referenced (i.e. used in an expression), then the
1167 symbol value is imported as an external reference that must be resolved by the
1168 linker. The **.extern** directive is merely a synonym for **.globl**.
1170 **.include** "*file*"
1172 Include a file. If the filename is not enclosed in quotes, then a default extension
1173 of "**.s**" is applied to it. If the filename is quoted, then the name is not changed
1176 Note: If the filename is not a valid symbol, then the assembler will generate an
1177 error message. You should enclose filenames such as "**atari.s**" in quotes,
1178 because such names are not symbols.
1180 If the include file cannot be found in the current directory, then the directory
1181 search path, as specified by -i on the commandline, or' by the 'RMACPATH'
1182 enviroment string, is traversed.
1186 Issue a page eject in the listing file.
1188 **.title** "*string*"
1190 **.subttl** [-] "*string*"
1192 Set the title or subtitle on the listing page. The title should be specified on
1193 the the first line of the source program in order to take effect on the first page.
1194 The second and subsequent uses of **.title** will cause page ejects. The second
1195 and subsequent uses of .subttl will cause page ejects unless the subtitle string
1196 is preceeded by a dash (-).
1202 Enable or disable source code listing. These directives increment and decrement
1203 an internal counter, so they may be appropriately nested. They have no effect
1204 if the **-l** switch is not specified on the commandline.
1208 This directive provides unstructured flow of control within a macro definition.
1209 It will transfer control to the line of the macro containing the specified goto
1210 label. A goto label is a symbol preceeded by a colon that appears in the first
1211 column of a source line within a macro definition:
1215 where the label itself can be any valid symbol name, followed immediately by
1216 whitespace and a valid source line (or end of line). The colon **must** appear in
1219 The goto-label is removed from the source line prior to macro expansion -
1220 to all intents and purposes the label is invisible except to the .goto directive
1221 Macro expansion does not take place within the label.
1223 For example, here is a silly way to count from 1 to 10 without using **.rept**:
1231 iif count <= 10, goto loop
1236 Switch to Jaguar GPU assembly mode. This directive must be used
1237 within the TEXT or DATA segments.
1240 No. Just... no. Don't ask about it. Ever.
1241 **.prgflags** *value*
1243 Sets ST executable .PRG field *PRGFLAGS* to *value*. *PRGFLAGS* is a bit field defined as follows:
1245 ============ ====== =======
1246 Definition Bit(s) Meaning
1247 ============ ====== =======
1248 PF_FASTLOAD 0 If set, clear only the BSS area on program load, otherwise clear the entire heap.
1249 PF_TTRAMLOAD 1 If set, the program may be loaded into alternative RAM, otherwise it must be loaded into standard RAM.
1250 PF_TTRAMMEM 2 If set, the program's Malloc() requests may be satisfied from alternative RAM, otherwise they must be satisfied from standard RAM.
1251 -- 3 Currently unused.
1252 See left. 4 & 5 If these bits are set to 0 (PF_PRIVATE), the processes' entire memory space will be considered private (when memory protection is enabled).If these bits are set to 1 (PF_GLOBAL), the processes' entire memory space will be readable and writable by any process (i.e. global).If these bits are set to 2 (PF_SUPERVISOR), the processes' entire memory space will only be readable and writable by itself and any other process in supervisor mode.If these bits are set to 3 (PF_READABLE), the processes' entire memory space will be readable by any application but only writable by itself.
1253 -- 6-15 Currently unused.
1254 ============ ====== =======
1256 **.regequ** *expression*
1257 Essentially the same as **.EQUR.** Included for compatibility with the GASM
1260 Essentially the same as **.EQURUNDEF.** Included for compatibility with
1269 All of the standard Motorola 68000 mnemonics and addressing modes are supported;
1270 you should refer to **The Motorola M68000 Programmer's Reference Manual**
1271 for a description of the instruction set and the allowable addressing modes for each
1272 instruction. With one major exception (forward branches) the assembler performs
1273 all the reasonable optimizations of instructions to their short or address register
1276 Register names may be in upper or lower case. The alternate forms ``R0`` through
1277 ``R15`` may be used to specify ``D0`` through ``A7``. All register names are keywords, and
1278 may not be used as labels or symbols. None of the 68010 or 68020 register names
1279 are keywords (but they may become keywords in the future).
1284 ===================================== ===========================================
1285 Assembler Syntax Description
1286 ===================================== ===========================================
1287 *Dn* Data register direct
1288 *An* Address register direct
1289 (*An*) Address register indirect
1290 (*An*)+ Address register indirect postincrement
1291 -(*An*) Address register indirect predecrement
1292 *disp*\ (*An*) Address register indirect with displacement
1293 *bdisp*\ (*An*, *Xi*\ [.\ *size*]) Address register indirect indexed
1294 *abs*.w Absolute short
1295 *abs* Absolute (long or short)
1296 *abs*.l Forced absolute long
1297 *disp*\ (PC) Program counter with displacement
1298 *bdisp*\ (PC, *Xi*\ ) Program counter indexed
1300 ===================================== ===========================================
1304 Since RMAC is a one pass assembler, forward branches cannot be automatically
1305 optimized to their short form. Instead, unsized forward branches are assumed to
1306 be long. Backward branches are always optimized to the short form if possible.
1308 A table that lists "extra" branch mnemonics (common synonyms for the Motorola
1309 defined mnemonics) appears below.
1311 `Linker Constraints`_
1312 '''''''''''''''''''''
1313 It is not possible to make an external reference that will fix up a byte. For example:
1318 move.l frog(pc,d0),d1
1320 is illegal (and generates an assembly error) when frog is external, because the
1321 displacement occupies a byte field in the 68000 offset word, which the object file
1326 ============== ========
1327 Alternate name Becomes:
1328 ============== ========
1338 ============== ========
1340 `Optimizations and Translations`_
1341 '''''''''''''''''''''''''''''''''
1342 The assembler provides "creature comforts" when it processes 68000 mnemonics:
1344 * **CLR.x An** will really generate **SUB.x An,An**.
1346 * **ADD**, **SUB** and **CMP** with an address register will really generate **ADDA**,
1347 **SUBA** and **CMPA**.
1349 * The **ADD**, **AND**, **CMP**, **EOR**, **OR** and **SUB** mnemonics with immediate
1350 first operands will generate the "I" forms of their instructions (**ADDI**, etc.) if
1351 the second operand is not register direct.
1353 * All shift instructions with no count value assume a count of one.
1355 * **MOVE.L** is optimized to **MOVEQ** if the immediate operand is defined and
1356 in the range -128...127. However, **ADD** and **SUB** are never translated to
1357 their quick forms; **ADDQ** and **SUBQ** must be explicit.
1359 * In GPU/DSP code sections, you can use JUMP (Rx) in place of JUMP T, (Rx) and JR
1360 (Rx) in place of JR T,(Rx).
1361 * RMAC tests all GPU/DSP restrictions and corrects them wherever possible (such as
1362 inserting a NOP instruction when needed).
1363 * The “(Rx+N)” addressing mode for GPU/DSP instructions is optimized to “(Rx)”
1368 `Macro declaration`_
1369 ''''''''''''''''''''
1370 A macro definition is a series of statements of the form:
1373 .macro name [ formal-arg, ...]
1377 statements making up the macro body
1383 The name of the macro may be any valid symbol that is not also a 68000 instruction
1384 or an assembler directive. (The name may begin with a period - macros cannot
1385 be made confined the way labels or equated symbols can be). The formal argument
1386 list is optional; it is specified with a comma-seperated list of valid symbol names.
1387 Note that there is no comma between the name of the macro and the name of the
1388 first formal argument.
1390 A macro body begins on the line after the **.macro** directive. All instructions
1391 and directives, except other macro definitions, are legal inside the body.
1393 The macro ends with the **.endm** statement. If a label appears on the line with
1394 this directive, the label is ignored and a warning is generated.
1396 `Parameter Substitution`_
1397 '''''''''''''''''''''''''
1398 Within the body, formal parameters may be expanded with the special forms:
1404 The second form (enclosed in braces) can be used in situations where the characters
1405 following the formal parameter name are valid symbol continuation characters. This
1406 is usually used to force concatentation, as in:
1411 \(godzilla}vs\{reagan}
1413 The formal parameter name is terminated with a character that is not valid in
1414 a symbol (e.g. whitespace or puncuation); optionally, the name may be enclosed in
1415 curly-braces. The names must be symbols appearing on the formal argument list,
1416 or a single decimal digit (``\1`` corresponds to the first argument, ``\2`` to the second,
1417 ``\9`` to the ninth, and ``\0`` to the tenth). It is possible for a macro to have more than
1418 ten formal arguments, but arguments 11 and on must be referenced by name, not
1421 Other special forms are:
1423 ============ ================================================
1424 Special Form Description
1425 ============ ================================================
1426 ``\\`` a single "\",
1427 ``\~`` a unique label of the form "Mn"
1428 ``\#`` the number of arguments actually specified
1429 ``\!`` the "dot-size" specified on the macro invocation
1430 ``\?name`` conditional expansion
1431 ``\?{name}`` conditional expansion
1432 ============ ================================================
1434 The last two forms are identical: if the argument is specified and is non-empty, the
1435 form expands to a "1", otherwise (if the argument is missing or empty) the form
1438 The form "``\!``" expands to the "dot-size" that was specified when the macro
1439 was invoked. This can be used to write macros that behave differently depending
1440 on the size suffix they are given, as in this macro which provides a synonym for the
1445 .macro deposit value
1448 deposit.b 1 ; byte of 1
1449 deposit.w 2 ; word of 2
1450 deposit.l 3 ; longvord of 3
1451 deposit 4 ; word of 4 (no explicit size)
1455 A previously-defined macro is called when its name appears in the operation field of
1456 a statement. Arguments may be specified following the macro name; each argument
1457 is seperated by a comma. Arguments may be empty. Arguments are stored for
1458 substitution in the macro body in the following manner:
1460 * Numbers are converted to hexadecimal.
1462 * All spaces outside strings are removed.
1464 * Keywords (such as register names, dot sizes and "^^" operators) are converted
1467 * Strings are enclosed in double-quote marks (").
1469 For example, a hypothetical call to the macro "``mymacro``", of the form:
1470 ``mymacro A0, , 'Zorch' / 32, "^^DEFINED foo, , , tick tock``
1472 will result in the translations:
1474 ======== ================= =================================================
1475 Argument Expansion Comment
1476 ======== ================= =================================================
1477 ``\1`` ``a0`` "``A0``" converted to lower-case
1479 ``\3`` ``"Zorch"/$20`` "``Zorch``" in double-quotes, 32 in hexadecimal
1480 ``\4`` ``^^defined foo`` "``^^DEFINED``" converted to lower-case
1483 ``\7`` ``ticktock`` spaces removed (note concatenation)
1484 ======== ================= =================================================
1486 The **.exitm** directive will cause an immediate exit from a macro body. Thus
1487 the macro definition:
1492 .iif !\?source, .exitm ; exit if source is empty
1493 move \source,d0 ; otherwise, deposit source
1496 will not generate the move instruction if the argument **"source"** is missing from
1497 the macro invocation.
1499 The **.end**, **.endif** and **.exitm** directives all pop-out of their include levels
1500 appropriately. That is, if a macro performs a **.include** to include a source file, an
1501 executed **.exitm** directive within the include-file will pop out of both the include-file
1504 Macros may be recursive or mutually recursive to any level, subject only to
1505 the availability of memory. When writing recursive macros, take care in the coding
1506 of the termination condition(s). A macro that repeatedly calls itself will cause the
1507 assembler to exhaust its memory and abort the assembly.
1512 The Gemdos macro is used to make file system calls. It has two parameters, a
1513 function number and the number of bytes to clean off the stack after the call. The
1514 macro pushes the function number onto the stack and does the trap to the file
1515 system. After the trap returns, conditional assembly is used to choose an addq or
1516 an **add.w** to remove the arguments that were pushed.
1520 .macro Gemdos trpno, clean
1521 move.w #\trpno,-(sp) ; push trap number
1522 trap #1 ; do GEMDOS trap
1524 addq #\clean,sp ; clean-up up to 8 bytes
1526 add.w #\clean,sp ; clean-up more than 8 bytes
1530 The Fopen macro is supplied two arguments; the address of a filename, and
1531 the open mode. Note that plain move instructions are used, and that the caller of
1532 the macro must supply an appropriate addressing mode (e.g. immediate) for each
1537 .macro Fopen file, mode
1538 movs.w \mode,-(sp) ;push open mode
1539 move.1 \file,-(sp) ;push address of tile name
1540 Gemdos $3d,8 ;do the GEMDOS call
1543 The **String** macro is used to allocate storage for a string, and to place the
1544 string's address somewhere. The first argument should be a string or other expres-
1545 sion acceptable in a dc.b directive. The second argument is optional; it specifies
1546 where the address of the string should be placed. If the second argument is omitted,
1547 the string's address is pushed onto the stack. The string data itself is kept in the
1552 .macro String str,loc
1553 .if \?loc ; if loc is defined
1554 move.l #.\~,\loc ; put the string's address there
1556 pea .\~ ; push the string's address
1558 .data ; put the string data
1559 .\~: dc.b \str,0 ; in the data segment
1560 .text ; and switch back to the text segment
1563 The construction "``.\~``" will expand to a label of the form "``.M``\ *n*" (where *n* is
1564 a unique number for every macro invocation), which is used to tag the location of
1565 the string. The label should be confined because the macro may be used along with
1566 other confined symbols.
1568 Unique symbol generation plays an important part in the art of writing fine
1569 macros. For instance, if we needed three unique symbols, we might write "``.a\~``",
1570 "``.b\~``" and "``.c\~``".
1574 Repeat-blocks provide a simple iteration capability. A repeat block allows a range
1575 of statements to be repeated a specified number of times. For instance, to generate
1576 a table consisting of the numbers 255 through 0 (counting backwards) you could
1581 .count set 255 ; initialize counter
1582 .rept 256 ; repeat 256 times:
1583 dc.b .count ; deposit counter
1584 .count set .count - 1 ; and decrement it
1585 .endr ; (end of repeat block)
1587 Repeat blocks can also be used to duplicate identical pieces of code (which are
1588 common in bitmap-graphics routines). For example:
1592 .rept 16 ; clear 16 words
1593 clr.w (a0)+ ; starting at AO
1596 `Jaguar GPU/DSP Mode`_
1597 ======================
1599 RMAC will generate code for the Atari jaguar GPU and DSP custom RISC (Reduced
1600 Instruction Set Computer) processors. See the Atari Jaguar Software reference Manual – Tom
1601 & Jerry for a complete listing of Jaguar GPU and DSP assembler mnemonics and addressing
1606 The following condition codes for the GPU/DSP JUMP and JR instructions are built-in:
1610 CC (Carry Clear) = %00100
1611 CS (Carry Set) = %01000
1614 NE (Not Equal) = %00001
1616 HI (Higher) = %00101
1622 RMAC will generate code for the Motorola 6502 microprocessor. This chapter
1623 describes extra addressing modes and directives used to support the 6502.
1625 As the 6502 object code is not linkable (currently there is no linker) external
1626 references may not be made. (Nevertheless, RMAC may reasonably be used for
1627 large assemblies because of its blinding speed.)
1629 `6502 Addressing Modes`_
1630 ''''''''''''''''''''''''
1631 All standard 6502 addressing modes are supported, with the exception of the
1632 accumulator addressing form, which must be omitted (e.g. "ror a" becomes "ror").
1633 Five extra modes, synonyms for existing ones, are included for compatibility with
1634 the Atari Coinop assembler.
1636 ============== ========================================
1637 *empty* implied or accumulator (e.g. tsx or ror)
1638 *expr* absolute or zeropage
1640 #<\ *expr* immediate low byte of a word
1641 #>\ *expr* immediate high byte of a word
1642 (*expr*,x) indirect X
1643 (*expr*),y indirect Y
1647 @\ *expr*\ (x) indirect X
1648 @\ *expr*\ (y) indirect Y
1650 x,\ *expr* indexed X
1651 y,\ *expr* indexed Y
1652 ============== ========================================
1657 This directive enters the 6502 section. The location counter is undefined, and
1658 must be set with ".org" before any code can be generated.
1660 The "``dc.w``" directive will produce 6502-format words (low byte first). The
1661 68000's reserved keywords (``d0-d7/a0-a7/ssp/usp`` and so on) remain reserved
1662 (and thus unusable) while in the 6502 section. The directives **globl**, **dc.l**,
1663 **dcb.l**, **text**, **data**, **bss**, **abs**, **even** and **comm** are illegal in the 6502 section.
1664 It is permitted, though probably not useful, to generate both 6502 and 68000
1665 code in the same object file.
1667 This directive leaves the 6502 segment and returns to the 68000's text segment.
1668 68000 instructions may be assembled as normal.
1670 This directive is only legal in the 6502 section. It sets the value of the location
1671 counter (or **pc**) to location, an expression that must be defined, absolute, and
1676 It is possible to assemble "beyond" the microprocessor's 64K address space, but
1677 attempting to do so will probably screw up the assembler. DO NOT attempt
1678 to generate code like this:
1687 the third NOP in this example, at location $10000, may cause the assembler
1688 to crash or exhibit spectacular schizophrenia. In any case, RMAC will give
1689 no warning before flaking out.
1691 `6502 Object Code Format`_
1692 ''''''''''''''''''''''''''
1693 Traditionally Madmac had a very kludgy way of storing object files. This has been
1694 replaced with a more standard *.exe* (or *.com* or *.xex* if you prefer). Briefly,
1695 the *.exe* format consists of chunks of this format (one after the other):
1700 00-01 $FFFF - Indicates a binary load file. Mandatory for first segment, optional for any other segment
1701 02-03 Start Address. The segment will load at this address
1702 04-05 End Address. The last byte to load for this segment
1703 06-.. The actual segment data to load (End Address-Start Address + 1 bytes)
1708 `When Things Go Wrong`_
1709 '''''''''''''''''''''''
1710 Most of RMAC's error messages are self-explanatory. They fall into four classes:
1711 warnings about situations that you (or the assembler) may not be happy about,
1712 errors that cause the assembler to not generate object files, fatal errors that cause
1713 the assembler to abort immediately, and internal errors that should never happen.\ [3]_
1715 You can write editor macros (or sed or awk scripts) to parse the error messages
1716 RMAC generates. When a message is printed, it is of the form:
1718 "*filename*" , ``line`` *line-number*: *message*
1720 The first element, a filename enclosed in double quotes, indicates the file that generated
1721 the error. The filename is followed by a comma, the word "``line``", and a line
1722 number, and finally a colon and the text of the message. The filename "**(\*top\*)**"
1723 indicates that the assembler could not determine which file had the problem.
1725 The following sections list warnings, errors and fatal errors in alphabetical
1726 order, along with a short description of what may have caused the problem.
1728 .. [3] 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.
1732 **bad backslash code in string**
1733 You tried to follow a backslash in a string with a character that the assembler
1734 didn't recognize. Remember that RMAC uses a C-style escape system in
1737 You specified a label before a macro, **rept** or **endm** directive. The assembler
1738 is warning you that the label will not be defined in the assembly.
1739 **unoptimized short branch**
1740 This warning is only generated if the -s switch is specified on the command
1741 line. The message refers to a forward, unsized long branch that you could have
1748 As a result of previous errors, the assembler cannot continue processing. The
1749 assembly is aborted.
1750 **line too long as a result of macro expansion**
1751 When a source line within a macro was expanded, the resultant line was too
1752 long for RMAC (longer than 200 characters or so).
1755 **memory exhausted**
1756 The assembler ran out of memory. You should (1) split up your source files
1757 and assemble them seperately, or (2) if you have any ramdisks or RAM-resident
1758 programs (like desk accessories) decrease their size so that the assembler has
1759 more RAM to work with. As a rule of thumb, pure 68000 code will use up to
1760 twice the number of bytes contained in the source files, whereas 6502 code will
1761 use 64K of ram right away, plus the size of the source files. The assembler itself
1762 uses about 80K bytes. Get out your calculator...
1764 The assembler ran across an **endm** directive when it wasn't expecting to see
1765 one. The assembly is aborted. Check the nesting of your macro definitions -
1766 you probably have an extra **endm**.
1774 Syntax error in **.cargs** directive.
1775 **.comm symbol already defined**
1777 You tried to ``.comm`` a symbol that was already defined.
1778 **.ds permitted only in BSS**
1780 You tried to use ``.ds`` in the text or data section.
1781 **.init not permitted in BSS or ABS**
1783 You tried to use ``.init`` in the BSS or ABS section.
1784 **.org permitted only in .6502 section**
1786 You tried to use ``.org`` in a 68000 section.
1787 **Cannot create:** *filename*
1789 The assembler could not create the indicated filename.
1790 **External quick reference**
1792 You tried to make the immediate operand of a **moveq**, **subq** or **addq** instruction external.
1793 **PC-relative expr across sections**
1795 You tried to make a PC-relative reference to a location contained in another
1797 **[bwsl] must follow '.' in symbol**
1799 You tried to follow a dot in a symbol name with something other than one of
1800 the four characters 'B', 'W', 'S' or 'L'.
1801 **addressing mode syntax**
1803 You made a syntax error in an addressing mode.
1806 One of your **.assert** directives failed!
1807 **bad (section) expression**
1809 You tried to mix and match sections in an expression
1810 **bad 6502 addressing mode**
1812 The 6502 mnemonic will not work with the addressing mode you specified.
1815 There's a syntax error in the expression you typed.
1816 **bad size specified**
1818 You tried to use an inappropriate size suffix for the instruction. Check your
1819 68000 manual for allowable sizes.
1822 You can't use .b (byte) mode with the **movem** instruction.
1823 **cannot .globl local symbol**
1825 You tried to make a confined symbol global or common.
1826 **cannot initialize non-storage (BSS) section**
1828 You tried to generate instructions (or data, with dc) in the BSS or ABS section.
1829 **cannot use '.b' with an address register**
1831 You tried to use a byte-size suffix with an address register. The 68000 does not
1832 perform byte-sized address register operations.
1833 **directive illegal in .6502 section**
1835 You tried to use a 68000-oriented directive in the 6502 section.
1838 The expression you typed involves a division by zero.
1839 **expression out of range**
1841 The expression you typed is out of range for its application.
1842 **external byte reference**
1844 You tried to make a byte-sized reference to an external symbol, which the
1845 object file format will not allow
1846 **external short branch**
1848 You tried to make a short branch to an external symbol, which the linker cannot
1850 **extra (unexpected) text found after addressing mode**
1852 RMAC thought it was done processing a line, but it ran up against "extra"
1853 stuff. Be sure that any comment on the line begins with a semicolon, and check
1854 for dangling commas, etc.
1855 **forward or undefined .assert**
1857 The expression you typed after a **.assert** directive had an undefined value.
1858 Remember that RMAC is one-pass.
1859 **hit EOF without finding matching .endif**
1861 The assembler fell off the end of last input file without finding a **.endif** to
1862 match an . it. You probably forgot a **.endif** somewhere.
1863 **illegal 6502 addressing mode**
1865 The 6502 instruction you typed doesn't work with the addressing mode you
1867 **illegal absolute expression**
1869 You can't use an absolute-valued expression here.
1870 **illegal bra.s with zero offset**
1872 You can't do a short branch to the very next instruction (read your 68000
1874 **illegal byte-sized relative reference**
1876 The object file format does not permit bytes contain relocatable values; you
1877 tried to use a byte-sized relocatable expression in an immediate addressing
1879 **illegal character**
1881 Your source file contains a character that RMAC doesn't allow. (most
1882 control characters fall into this category).
1883 **illegal initialization of section**
1885 You tried to use .dc or .dcb in the BSS or ABS sections.
1886 **illegal relative address**
1888 The relative address you specified is illegal because it belongs to a different
1890 **illegal word relocatable (in .PRG mode)**
1892 You can't have anything other than long relocatable values when you're gener-
1893 ating a **.PRG** file.
1894 **inappropriate addressing mode**
1896 The mnemonic you typed doesn't work with the addressing modes you specified.
1897 Check your 68000 manual for allowable combinations.
1898 **invalid addressing mode**
1900 The combination of addressing modes you picked for the **movem** instruction
1901 are not implemented by the 68000. Check your 68000 reference manual for
1903 **invalid symbol following ^^**
1905 What followed the ^^ wasn't a valid symbol at all.
1906 **mis-nested .endr**
1908 The assembler found a **.endr** directive when it wasn't prepared to find one.
1909 Check your repeat-block nesting.
1910 **mismatched .else**
1912 The assembler found a **.else** directive when it wasn't prepared to find one.
1913 Check your conditional assembly nesting.
1914 **mismatched .endif**
1916 The assembler found a **.endif** directive when it wasn't prepared to find one.
1917 Check your conditional assembly nesting.
1923 **missing argument name**
1925 **missing close parenthesis ')'**
1927 **missing close parenthesis ']'**
1931 **missing filename**
1937 **missing symbol or string**
1939 The assembler expected to see a symbol/filename/string (etc...), but found
1940 something else instead. In most cases the problem should be obvious.
1941 **misuse of '.', not allowed in symbols**
1943 You tried to use a dot (.) in the middle of a symbol name.
1946 The expression you typed involves a modulo by zero.
1947 **multiple formal argument definition**
1949 The list of formal parameter names you supplied for a macro definition includes
1950 two identical names.
1951 **multiple macro definition**
1953 You tried to define a macro which already had a definition.
1954 **non-absolute byte reference**
1956 You tried to make a byte reference to a relocatable value, which the object file
1957 format does not allow.
1958 **non-absolute byte value**
1960 You tried to dc.b or dcb.b a relocatable value. Byte relocatable values are
1961 not permitted by the object file format.
1962 **register list order**
1964 You tried to specify a register list like **D7-D0**, which is illegal. Remember
1965 that the first register number must be less than or equal to the second register
1967 **register list syntax**
1969 You made an error in specifying a register list for a **.reg** directive or a **.movem**
1971 **symbol list syntax**
1973 You probably forgot a comma between the names of two symbols in a symbol
1974 list, or you left a comma dangling on the end of the line.
1977 This is a "catch-all" error.
1978 **undefined expression**
1980 The expression has an undefined value because of a forward reference, or an
1981 undefined or external symbol.
1982 **unimplemented addressing mode**
1984 You tried to use 68020 "square-bracket" notation for a 68020 addressing mode.
1985 RMAC does not support 68020 addressing modes.
1986 **unimplemented directive**
1988 You have found a directive that didn't appear in the documentation. It doesn't
1990 **unimplemented mnemonic**
1992 You've found an assembler for documentation) bug.
1993 **unknown symbol following ^^**
1995 You followed a ^^ with something other than one of the names defined, ref-
1997 **unsupported 68020 addressing mode**
1999 The assembler saw a 68020-type addressing mode. RMAC does not assem-
2000 ble code for the 68020 or 68010.
2001 **unterminated string**
2003 You specified a string starting with a single or double quote, but forgot to type
2007 The assembler had a problem writing an object file. This is usually caused by
2008 a full disk, or a bad sector on the media.