1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 2000
3 @c Free Software Foundation, Inc.
4 @c UPDATE!! On future updates--
5 @c (1) check for new machine-dep cmdline options in
6 @c md_parse_option definitions in config/tc-*.c
7 @c (2) for platform-specific directives, examine md_pseudo_op
9 @c (3) for object-format specific directives, examine obj_pseudo_op
11 @c (4) portable directives in potable[] in read.c
15 @c defaults, config file may override:
18 @include asconfig.texi
21 @c common OR combinations of conditions
41 @set abnormal-separator
45 @settitle Using @value{AS}
48 @settitle Using @value{AS} (@value{TARGET})
50 @setchapternewpage odd
55 @c WARE! Some of the machine-dependent sections contain tables of machine
56 @c instructions. Except in multi-column format, these tables look silly.
57 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
58 @c the multi-col format is faked within @example sections.
60 @c Again unfortunately, the natural size that fits on a page, for these tables,
61 @c is different depending on whether or not smallbook is turned on.
62 @c This matters, because of order: text flow switches columns at each page
65 @c The format faked in this source works reasonably well for smallbook,
66 @c not well for the default large-page format. This manual expects that if you
67 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
68 @c tables in question. You can turn on one without the other at your
69 @c discretion, of course.
72 @c the insn tables look just as silly in info files regardless of smallbook,
73 @c might as well show 'em anyways.
79 * As: (as). The GNU assembler.
88 This file documents the GNU Assembler "@value{AS}".
90 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
92 Permission is granted to copy, distribute and/or modify this document
93 under the terms of the GNU Free Documentation License, Version 1.1
94 or any later version published by the Free Software Foundation;
95 with no Invariant Sections, with no Front-Cover Texts, and with no
96 Back-Cover Texts. A copy of the license is included in the
97 section entitled "GNU Free Documentation License".
100 Permission is granted to process this file through Tex and print the
101 results, provided the printed document carries copying permission
102 notice identical to this one except for the removal of this paragraph
103 (this paragraph not being relevant to the printed manual).
109 @title Using @value{AS}
110 @subtitle The @sc{gnu} Assembler
112 @subtitle for the @value{TARGET} family
115 @subtitle Version @value{VERSION}
118 The Free Software Foundation Inc. thanks The Nice Computer
119 Company of Australia for loaning Dean Elsner to write the
120 first (Vax) version of @code{as} for Project @sc{gnu}.
121 The proprietors, management and staff of TNCCA thank FSF for
122 distracting the boss while they got some work
125 @author Dean Elsner, Jay Fenlason & friends
129 \hfill {\it Using {\tt @value{AS}}}\par
130 \hfill Edited by Cygnus Support\par
132 %"boxit" macro for figures:
133 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
134 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
135 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
136 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
137 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
140 @vskip 0pt plus 1filll
141 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
143 Permission is granted to copy, distribute and/or modify this document
144 under the terms of the GNU Free Documentation License, Version 1.1
145 or any later version published by the Free Software Foundation;
146 with no Invariant Sections, with no Front-Cover Texts, and with no
147 Back-Cover Texts. A copy of the license is included in the
148 section entitled "GNU Free Documentation License".
154 @top Using @value{AS}
156 This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version
159 This version of the file describes @code{@value{AS}} configured to generate
160 code for @value{TARGET} architectures.
163 This document is distributed under the terms of the GNU Free
164 Documentation License. A copy of the license is included in the
165 section entitled "GNU Free Documentation License".
168 * Overview:: Overview
169 * Invoking:: Command-Line Options
171 * Sections:: Sections and Relocation
173 * Expressions:: Expressions
174 * Pseudo Ops:: Assembler Directives
175 * Machine Dependencies:: Machine Dependent Features
176 * Reporting Bugs:: Reporting Bugs
177 * Acknowledgements:: Who Did What
178 * GNU Free Documentation License:: GNU Free Documentation License
186 This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}.
188 This version of the manual describes @code{@value{AS}} configured to generate
189 code for @value{TARGET} architectures.
193 @cindex invocation summary
194 @cindex option summary
195 @cindex summary of options
196 Here is a brief summary of how to invoke @code{@value{AS}}. For details,
197 @pxref{Invoking,,Comand-Line Options}.
199 @c We don't use deffn and friends for the following because they seem
200 @c to be limited to one line for the header.
202 @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ]
203 [ -f ] [ --gstabs ] [ --gdwarf2 ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ]
204 [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ]
205 [ -version ] [ --version ] [ -W ] [ --warn ] [ --fatal-warnings ]
206 [ -w ] [ -x ] [ -Z ] [ --target-help ]
208 @c am29k has no machine-dependent assembler options
211 [ -mbig-endian | -mlittle-endian ]
214 [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]60 |
215 -m[arm]600 | -m[arm]610 | -m[arm]620 | -m[arm]7[t][[d]m[i]][fe] | -m[arm]70 |
216 -m[arm]700 | -m[arm]710[c] | -m[arm]7100 | -m[arm]7500 | -m[arm]8 |
217 -m[arm]810 | -m[arm]9 | -m[arm]920 | -m[arm]920t | -m[arm]9tdmi |
218 -mstrongarm | -mstrongarm110 | -mstrongarm1100 ]
219 [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t |
220 -m[arm]v5 | -[arm]v5t ]
222 [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ]
224 [ -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant ]
225 [ -mthumb-interwork ]
236 @c Hitachi family chips have no machine-dependent assembler options
239 @c HPPA has no machine-dependent assembler options (yet).
245 @c The order here is important. See c-sparc.texi.
246 [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
247 -Av8plus | -Av8plusa | -Av9 | -Av9a ]
248 [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ]
251 [ -mcpu=54[123589] | -mcpu=54[56]lp ] [ -mfar-mode | -mf ]
252 [ -merrors-to-file <filename> | -me <filename> ]
255 @c Z8000 has no machine-dependent assembler options
258 @c see md_parse_option in tc-i960.c
259 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
263 [ --m32rx | --[no-]warn-explicit-parallel-conflicts | --W[n]p ]
266 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ]
269 [ -jsri2bsr ] [ -sifilter ] [ -relax ]
273 [ -m68hc11 | -m68hc12 ]
274 [ --force-long-branchs ] [ --short-branchs ] [ --strict-direct-mode ]
275 [ --print-insn-syntax ] [ --print-opcodes ] [ --generate-example ]
278 [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ]
279 [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -mips4 ] [ -mips5 ]
280 [ -mips32 ] [ -mips64 ]
281 [ -m4650 ] [ -no-m4650 ]
282 [ --trap ] [ --break ]
283 [ --emulation=@var{name} ]
285 [ -- | @var{files} @dots{} ]
290 Turn on listings, in any of a variety of ways:
294 omit false conditionals
297 omit debugging directives
300 include high-level source
306 include macro expansions
309 omit forms processing
315 set the name of the listing file
318 You may combine these options; for example, use @samp{-aln} for assembly
319 listing without forms processing. The @samp{=file} option, if used, must be
320 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
323 Ignored. This option is accepted for script compatibility with calls to
326 @item --defsym @var{sym}=@var{value}
327 Define the symbol @var{sym} to be @var{value} before assembling the input file.
328 @var{value} must be an integer constant. As in C, a leading @samp{0x}
329 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
332 ``fast''---skip whitespace and comment preprocessing (assume source is
336 Generate stabs debugging information for each assembler line. This
337 may help debugging assembler code, if the debugger can handle it.
340 Generate DWARF2 debugging information for each assembler line. This
341 may help debugging assembler code, if the debugger can handle it. Note - this
342 option is only supported by some targets, not all of them.
345 Print a summary of the command line options and exit.
348 Print a summary of all target specific options and exit.
351 Add directory @var{dir} to the search list for @code{.include} directives.
354 Don't warn about signed overflow.
357 @ifclear DIFF-TBL-KLUGE
358 This option is accepted but has no effect on the @value{TARGET} family.
360 @ifset DIFF-TBL-KLUGE
361 Issue warnings when difference tables altered for long displacements.
366 Keep (in the symbol table) local symbols. On traditional a.out systems
367 these start with @samp{L}, but different systems have different local
370 @item -o @var{objfile}
371 Name the object-file output from @code{@value{AS}} @var{objfile}.
374 Fold the data section into the text section.
377 Print the maximum space (in bytes) and total time (in seconds) used by
380 @item --strip-local-absolute
381 Remove local absolute symbols from the outgoing symbol table.
385 Print the @code{as} version.
388 Print the @code{as} version and exit.
392 Suppress warning messages.
394 @item --fatal-warnings
395 Treat warnings as errors.
398 Don't suppress warning messages or treat them as errors.
407 Generate an object file even after errors.
409 @item -- | @var{files} @dots{}
410 Standard input, or source files to assemble.
415 The following options are available when @value{AS} is configured for
420 @cindex ARC endianness
421 @cindex endianness, ARC
422 @cindex big endian output, ARC
424 Generate ``big endian'' format output.
426 @cindex little endian output, ARC
427 @item -mlittle-endian
428 Generate ``little endian'' format output.
434 The following options are available when @value{AS} is configured for the ARM
438 @item -m[arm][1|2|3|6|7|8|9][...]
439 Specify which ARM processor variant is the target.
440 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
441 Specify which ARM architecture variant is used by the target.
442 @item -mthumb | -mall
443 Enable or disable Thumb only instruction decoding.
444 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
445 Select which Floating Point architcture is the target.
446 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
447 Select which procedure calling convention is in use.
449 Select either big-endian (-EB) or little-endian (-EL) output.
450 @item -mthumb-interwork
451 Specify that the code has been generated with interworking between Thumb and
454 Specify that PIC code has been generated.
459 The following options are available when @value{AS} is configured for
462 @cindex D10V optimization
463 @cindex optimization, D10V
465 Optimize output by parallelizing instructions.
470 The following options are available when @value{AS} is configured for a D30V
473 @cindex D30V optimization
474 @cindex optimization, D30V
476 Optimize output by parallelizing instructions.
480 Warn when nops are generated.
482 @cindex D30V nops after 32-bit multiply
484 Warn when a nop after a 32-bit multiply instruction is generated.
489 The following options are available when @value{AS} is configured for the
490 Intel 80960 processor.
493 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
494 Specify which variant of the 960 architecture is the target.
497 Add code to collect statistics about branches taken.
500 Do not alter compare-and-branch instructions for long displacements;
507 The following options are available when @value{AS} is configured for the
508 Mitsubishi M32R series.
513 Specify which processor in the M32R family is the target. The default
514 is normally the M32R, but this option changes it to the M32RX.
516 @item --warn-explicit-parallel-conflicts or --Wp
517 Produce warning messages when questionable parallel constructs are
520 @item --no-warn-explicit-parallel-conflicts or --Wnp
521 Do not produce warning messages when questionable parallel constructs are
528 The following options are available when @value{AS} is configured for the
529 Motorola 68000 series.
534 Shorten references to undefined symbols, to one word instead of two.
536 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060
537 @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200
538 Specify what processor in the 68000 family is the target. The default
539 is normally the 68020, but this can be changed at configuration time.
541 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
542 The target machine does (or does not) have a floating-point coprocessor.
543 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
544 the basic 68000 is not compatible with the 68881, a combination of the
545 two can be specified, since it's possible to do emulation of the
546 coprocessor instructions with the main processor.
548 @item -m68851 | -mno-68851
549 The target machine does (or does not) have a memory-management
550 unit coprocessor. The default is to assume an MMU for 68020 and up.
556 The following options are available when @value{AS} is configured for
557 a picoJava processor.
561 @cindex PJ endianness
562 @cindex endianness, PJ
563 @cindex big endian output, PJ
565 Generate ``big endian'' format output.
567 @cindex little endian output, PJ
569 Generate ``little endian'' format output.
575 The following options are available when @value{AS} is configured for the
576 Motorola 68HC11 or 68HC12 series.
580 @item -m68hc11 | -m68hc12
581 Specify what processor is the target. The default is
582 defined by the configuration option when building the assembler.
584 @item --force-long-branchs
585 Relative branches are turned into absolute ones. This concerns
586 conditional branches, unconditional branches and branches to a
589 @item -S | --short-branchs
590 Do not turn relative branchs into absolute ones
591 when the offset is out of range.
593 @item --strict-direct-mode
594 Do not turn the direct addressing mode into extended addressing mode
595 when the instruction does not support direct addressing mode.
597 @item --print-insn-syntax
598 Print the syntax of instruction in case of error.
600 @item --print-opcodes
601 print the list of instructions with syntax and then exit.
603 @item --generate-example
604 print an example of instruction for each possible instruction and then exit.
605 This option is only useful for testing @code{@value{AS}}.
611 The following options are available when @code{@value{AS}} is configured
612 for the SPARC architecture:
615 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
616 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
617 Explicitly select a variant of the SPARC architecture.
619 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
620 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
622 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
623 UltraSPARC extensions.
625 @item -xarch=v8plus | -xarch=v8plusa
626 For compatibility with the Solaris v9 assembler. These options are
627 equivalent to -Av8plus and -Av8plusa, respectively.
630 Warn when the assembler switches to another architecture.
635 The following options are available when @value{AS} is configured for the 'c54x
640 Enable extended addressing mode. All addresses and relocations will assume
641 extended addressing (usually 23 bits).
642 @item -mcpu=@var{CPU_VERSION}
643 Sets the CPU version being compiled for.
644 @item -merrors-to-file @var{FILENAME}
645 Redirect error output to a file, for broken systems which don't support such
646 behaviour in the shell.
651 The following options are available when @value{AS} is configured for
656 This option sets the largest size of an object that can be referenced
657 implicitly with the @code{gp} register. It is only accepted for targets that
658 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
660 @cindex MIPS endianness
661 @cindex endianness, MIPS
662 @cindex big endian output, MIPS
664 Generate ``big endian'' format output.
666 @cindex little endian output, MIPS
668 Generate ``little endian'' format output.
676 Generate code for a particular MIPS Instruction Set Architecture level.
677 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
678 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
680 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
681 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
682 processors, respectively.
686 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
687 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
688 instructions around accesses to the @samp{HI} and @samp{LO} registers.
689 @samp{-no-m4650} turns off this option.
691 @item -mcpu=@var{CPU}
692 Generate code for a particular MIPS cpu. This has little effect on the
693 assembler, but it is passed by @code{@value{GCC}}.
696 @item --emulation=@var{name}
697 This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured
698 for some other target, in all respects, including output format (choosing
699 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
700 debugging information or store symbol table information, and default
701 endianness. The available configuration names are: @samp{mipsecoff},
702 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
703 @samp{mipsbelf}. The first two do not alter the default endianness from that
704 of the primary target for which the assembler was configured; the others change
705 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
706 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
707 selection in any case.
709 This option is currently supported only when the primary target
710 @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
711 Furthermore, the primary target or others specified with
712 @samp{--enable-targets=@dots{}} at configuration time must include support for
713 the other format, if both are to be available. For example, the Irix 5
714 configuration includes support for both.
716 Eventually, this option will support more configurations, with more
717 fine-grained control over the assembler's behavior, and will be supported for
721 @code{@value{AS}} ignores this option. It is accepted for compatibility with
729 Control how to deal with multiplication overflow and division by zero.
730 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
731 (and only work for Instruction Set Architecture level 2 and higher);
732 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
738 The following options are available when @value{AS} is configured for
744 Enable or disable the JSRI to BSR transformation. By default this is enabled.
745 The command line option @samp{-nojsri2bsr} can be used to disable it.
749 Enable or disable the silicon filter behaviour. By default this is disabled.
750 The default can be overidden by the @samp{-sifilter} command line option.
753 Alter jump instructions for long displacements.
755 @item -mcpu=[210|340]
756 Select the cpu type on the target hardware. This controls which instructions
760 Assemble for a big endian target.
763 Assemble for a little endian target.
769 * Manual:: Structure of this Manual
770 * GNU Assembler:: The GNU Assembler
771 * Object Formats:: Object File Formats
772 * Command Line:: Command Line
773 * Input Files:: Input Files
774 * Object:: Output (Object) File
775 * Errors:: Error and Warning Messages
779 @section Structure of this Manual
781 @cindex manual, structure and purpose
782 This manual is intended to describe what you need to know to use
783 @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
784 notation for symbols, constants, and expressions; the directives that
785 @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
788 We also cover special features in the @value{TARGET}
789 configuration of @code{@value{AS}}, including assembler directives.
792 This manual also describes some of the machine-dependent features of
793 various flavors of the assembler.
796 @cindex machine instructions (not covered)
797 On the other hand, this manual is @emph{not} intended as an introduction
798 to programming in assembly language---let alone programming in general!
799 In a similar vein, we make no attempt to introduce the machine
800 architecture; we do @emph{not} describe the instruction set, standard
801 mnemonics, registers or addressing modes that are standard to a
802 particular architecture.
804 You may want to consult the manufacturer's
805 machine architecture manual for this information.
809 For information on the H8/300 machine instruction set, see @cite{H8/300
810 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
811 see @cite{H8/300H Series Programming Manual} (Hitachi).
814 For information on the H8/500 machine instruction set, see @cite{H8/500
815 Series Programming Manual} (Hitachi M21T001).
818 For information on the Hitachi SH machine instruction set, see
819 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
822 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
826 @c I think this is premature---doc@cygnus.com, 17jan1991
828 Throughout this manual, we assume that you are running @dfn{GNU},
829 the portable operating system from the @dfn{Free Software
830 Foundation, Inc.}. This restricts our attention to certain kinds of
831 computer (in particular, the kinds of computers that @sc{gnu} can run on);
832 once this assumption is granted examples and definitions need less
835 @code{@value{AS}} is part of a team of programs that turn a high-level
836 human-readable series of instructions into a low-level
837 computer-readable series of instructions. Different versions of
838 @code{@value{AS}} are used for different kinds of computer.
841 @c There used to be a section "Terminology" here, which defined
842 @c "contents", "byte", "word", and "long". Defining "word" to any
843 @c particular size is confusing when the .word directive may generate 16
844 @c bits on one machine and 32 bits on another; in general, for the user
845 @c version of this manual, none of these terms seem essential to define.
846 @c They were used very little even in the former draft of the manual;
847 @c this draft makes an effort to avoid them (except in names of
851 @section The GNU Assembler
853 @sc{gnu} @code{as} is really a family of assemblers.
855 This manual describes @code{@value{AS}}, a member of that family which is
856 configured for the @value{TARGET} architectures.
858 If you use (or have used) the @sc{gnu} assembler on one architecture, you
859 should find a fairly similar environment when you use it on another
860 architecture. Each version has much in common with the others,
861 including object file formats, most assembler directives (often called
862 @dfn{pseudo-ops}) and assembler syntax.@refill
864 @cindex purpose of @sc{gnu} assembler
865 @code{@value{AS}} is primarily intended to assemble the output of the
866 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
867 @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
868 assemble correctly everything that other assemblers for the same
869 machine would assemble.
871 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
874 @c This remark should appear in generic version of manual; assumption
875 @c here is that generic version sets M680x0.
876 This doesn't mean @code{@value{AS}} always uses the same syntax as another
877 assembler for the same architecture; for example, we know of several
878 incompatible versions of 680x0 assembly language syntax.
881 Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
882 program in one pass of the source file. This has a subtle impact on the
883 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
886 @section Object File Formats
888 @cindex object file format
889 The @sc{gnu} assembler can be configured to produce several alternative
890 object file formats. For the most part, this does not affect how you
891 write assembly language programs; but directives for debugging symbols
892 are typically different in different file formats. @xref{Symbol
893 Attributes,,Symbol Attributes}.
896 On the @value{TARGET}, @code{@value{AS}} is configured to produce
897 @value{OBJ-NAME} format object files.
899 @c The following should exhaust all configs that set MULTI-OBJ, ideally
901 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
902 @code{a.out} or COFF format object files.
905 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
906 @code{b.out} or COFF format object files.
909 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
910 SOM or ELF format object files.
915 @section Command Line
917 @cindex command line conventions
918 After the program name @code{@value{AS}}, the command line may contain
919 options and file names. Options may appear in any order, and may be
920 before, after, or between file names. The order of file names is
923 @cindex standard input, as input file
925 @file{--} (two hyphens) by itself names the standard input file
926 explicitly, as one of the files for @code{@value{AS}} to assemble.
928 @cindex options, command line
929 Except for @samp{--} any command line argument that begins with a
930 hyphen (@samp{-}) is an option. Each option changes the behavior of
931 @code{@value{AS}}. No option changes the way another option works. An
932 option is a @samp{-} followed by one or more letters; the case of
933 the letter is important. All options are optional.
935 Some options expect exactly one file name to follow them. The file
936 name may either immediately follow the option's letter (compatible
937 with older assemblers) or it may be the next command argument (@sc{gnu}
938 standard). These two command lines are equivalent:
941 @value{AS} -o my-object-file.o mumble.s
942 @value{AS} -omy-object-file.o mumble.s
949 @cindex source program
951 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
952 describe the program input to one run of @code{@value{AS}}. The program may
953 be in one or more files; how the source is partitioned into files
954 doesn't change the meaning of the source.
956 @c I added "con" prefix to "catenation" just to prove I can overcome my
957 @c APL training... doc@cygnus.com
958 The source program is a concatenation of the text in all the files, in the
961 Each time you run @code{@value{AS}} it assembles exactly one source
962 program. The source program is made up of one or more files.
963 (The standard input is also a file.)
965 You give @code{@value{AS}} a command line that has zero or more input file
966 names. The input files are read (from left file name to right). A
967 command line argument (in any position) that has no special meaning
968 is taken to be an input file name.
970 If you give @code{@value{AS}} no file names it attempts to read one input file
971 from the @code{@value{AS}} standard input, which is normally your terminal. You
972 may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
975 Use @samp{--} if you need to explicitly name the standard input file
976 in your command line.
978 If the source is empty, @code{@value{AS}} produces a small, empty object
981 @subheading Filenames and Line-numbers
983 @cindex input file linenumbers
984 @cindex line numbers, in input files
985 There are two ways of locating a line in the input file (or files) and
986 either may be used in reporting error messages. One way refers to a line
987 number in a physical file; the other refers to a line number in a
988 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
990 @dfn{Physical files} are those files named in the command line given
991 to @code{@value{AS}}.
993 @dfn{Logical files} are simply names declared explicitly by assembler
994 directives; they bear no relation to physical files. Logical file names help
995 error messages reflect the original source file, when @code{@value{AS}} source
996 is itself synthesized from other files. @code{@value{AS}} understands the
997 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
998 @ref{File,,@code{.file}}.
1001 @section Output (Object) File
1007 Every time you run @code{@value{AS}} it produces an output file, which is
1008 your assembly language program translated into numbers. This file
1009 is the object file. Its default name is
1017 @code{b.out} when @code{@value{AS}} is configured for the Intel 80960.
1019 You can give it another name by using the @code{-o} option. Conventionally,
1020 object file names end with @file{.o}. The default name is used for historical
1021 reasons: older assemblers were capable of assembling self-contained programs
1022 directly into a runnable program. (For some formats, this isn't currently
1023 possible, but it can be done for the @code{a.out} format.)
1027 The object file is meant for input to the linker @code{@value{LD}}. It contains
1028 assembled program code, information to help @code{@value{LD}} integrate
1029 the assembled program into a runnable file, and (optionally) symbolic
1030 information for the debugger.
1032 @c link above to some info file(s) like the description of a.out.
1033 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1036 @section Error and Warning Messages
1038 @cindex error messsages
1039 @cindex warning messages
1040 @cindex messages from assembler
1041 @code{@value{AS}} may write warnings and error messages to the standard error
1042 file (usually your terminal). This should not happen when a compiler
1043 runs @code{@value{AS}} automatically. Warnings report an assumption made so
1044 that @code{@value{AS}} could keep assembling a flawed program; errors report a
1045 grave problem that stops the assembly.
1047 @cindex format of warning messages
1048 Warning messages have the format
1051 file_name:@b{NNN}:Warning Message Text
1055 @cindex line numbers, in warnings/errors
1056 (where @b{NNN} is a line number). If a logical file name has been given
1057 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1058 the current input file is used. If a logical line number was given
1060 (@pxref{Line,,@code{.line}})
1064 (@pxref{Line,,@code{.line}})
1067 (@pxref{Ln,,@code{.ln}})
1070 then it is used to calculate the number printed,
1071 otherwise the actual line in the current source file is printed. The
1072 message text is intended to be self explanatory (in the grand Unix
1075 @cindex format of error messages
1076 Error messages have the format
1078 file_name:@b{NNN}:FATAL:Error Message Text
1080 The file name and line number are derived as for warning
1081 messages. The actual message text may be rather less explanatory
1082 because many of them aren't supposed to happen.
1085 @chapter Command-Line Options
1087 @cindex options, all versions of assembler
1088 This chapter describes command-line options available in @emph{all}
1089 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1091 to the @value{TARGET}.
1094 to particular machine architectures.
1097 If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2),
1098 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1099 The assembler arguments must be separated from each other (and the @samp{-Wa})
1100 by commas. For example:
1103 gcc -c -g -O -Wa,-alh,-L file.c
1107 This passes two options to the assembler: @samp{-alh} (emit a listing to
1108 standard output with with high-level and assembly source) and @samp{-L} (retain
1109 local symbols in the symbol table).
1111 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1112 command-line options are automatically passed to the assembler by the compiler.
1113 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1114 precisely what options it passes to each compilation pass, including the
1118 * a:: -a[cdhlns] enable listings
1119 * D:: -D for compatibility
1120 * f:: -f to work faster
1121 * I:: -I for .include search path
1122 @ifclear DIFF-TBL-KLUGE
1123 * K:: -K for compatibility
1125 @ifset DIFF-TBL-KLUGE
1126 * K:: -K for difference tables
1129 * L:: -L to retain local labels
1130 * M:: -M or --mri to assemble in MRI compatibility mode
1131 * MD:: --MD for dependency tracking
1132 * o:: -o to name the object file
1133 * R:: -R to join data and text sections
1134 * statistics:: --statistics to see statistics about assembly
1135 * traditional-format:: --traditional-format for compatible output
1136 * v:: -v to announce version
1137 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1138 * Z:: -Z to make object file even after errors
1142 @section Enable Listings: @code{-a[cdhlns]}
1151 @cindex listings, enabling
1152 @cindex assembly listings, enabling
1154 These options enable listing output from the assembler. By itself,
1155 @samp{-a} requests high-level, assembly, and symbols listing.
1156 You can use other letters to select specific options for the list:
1157 @samp{-ah} requests a high-level language listing,
1158 @samp{-al} requests an output-program assembly listing, and
1159 @samp{-as} requests a symbol table listing.
1160 High-level listings require that a compiler debugging option like
1161 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1164 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1165 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1166 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1167 omitted from the listing.
1169 Use the @samp{-ad} option to omit debugging directives from the
1172 Once you have specified one of these options, you can further control
1173 listing output and its appearance using the directives @code{.list},
1174 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1176 The @samp{-an} option turns off all forms processing.
1177 If you do not request listing output with one of the @samp{-a} options, the
1178 listing-control directives have no effect.
1180 The letters after @samp{-a} may be combined into one option,
1181 @emph{e.g.}, @samp{-aln}.
1187 This option has no effect whatsoever, but it is accepted to make it more
1188 likely that scripts written for other assemblers also work with
1192 @section Work Faster: @code{-f}
1195 @cindex trusted compiler
1196 @cindex faster processing (@code{-f})
1197 @samp{-f} should only be used when assembling programs written by a
1198 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1199 and comment preprocessing on
1200 the input file(s) before assembling them. @xref{Preprocessing,
1204 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1205 preprocessed (if they contain comments, for example), @code{@value{AS}} does
1210 @section @code{.include} search path: @code{-I} @var{path}
1212 @kindex -I @var{path}
1213 @cindex paths for @code{.include}
1214 @cindex search path for @code{.include}
1215 @cindex @code{include} directive search path
1216 Use this option to add a @var{path} to the list of directories
1217 @code{@value{AS}} searches for files specified in @code{.include}
1218 directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
1219 many times as necessary to include a variety of paths. The current
1220 working directory is always searched first; after that, @code{@value{AS}}
1221 searches any @samp{-I} directories in the same order as they were
1222 specified (left to right) on the command line.
1225 @section Difference Tables: @code{-K}
1228 @ifclear DIFF-TBL-KLUGE
1229 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1230 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1231 where it can be used to warn when the assembler alters the machine code
1232 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1233 family does not have the addressing limitations that sometimes lead to this
1234 alteration on other platforms.
1237 @ifset DIFF-TBL-KLUGE
1238 @cindex difference tables, warning
1239 @cindex warning for altered difference tables
1240 @code{@value{AS}} sometimes alters the code emitted for directives of the form
1241 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1242 You can use the @samp{-K} option if you want a warning issued when this
1247 @section Include Local Labels: @code{-L}
1250 @cindex local labels, retaining in output
1251 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1252 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1253 debugging, because they are intended for the use of programs (like
1254 compilers) that compose assembler programs, not for your notice.
1255 Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1256 normally debug with them.
1258 This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
1259 in the object file. Usually if you do this you also tell the linker
1260 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1262 By default, a local label is any label beginning with @samp{L}, but each
1263 target is allowed to redefine the local label prefix.
1265 On the HPPA local labels begin with @samp{L$}.
1269 @section Assemble in MRI Compatibility Mode: @code{-M}
1272 @cindex MRI compatibility mode
1273 The @code{-M} or @code{--mri} option selects MRI compatibility mode. This
1274 changes the syntax and pseudo-op handling of @code{@value{AS}} to make it
1275 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1276 configured target) assembler from Microtec Research. The exact nature of the
1277 MRI syntax will not be documented here; see the MRI manuals for more
1278 information. Note in particular that the handling of macros and macro
1279 arguments is somewhat different. The purpose of this option is to permit
1280 assembling existing MRI assembler code using @code{@value{AS}}.
1282 The MRI compatibility is not complete. Certain operations of the MRI assembler
1283 depend upon its object file format, and can not be supported using other object
1284 file formats. Supporting these would require enhancing each object file format
1285 individually. These are:
1288 @item global symbols in common section
1290 The m68k MRI assembler supports common sections which are merged by the linker.
1291 Other object file formats do not support this. @code{@value{AS}} handles
1292 common sections by treating them as a single common symbol. It permits local
1293 symbols to be defined within a common section, but it can not support global
1294 symbols, since it has no way to describe them.
1296 @item complex relocations
1298 The MRI assemblers support relocations against a negated section address, and
1299 relocations which combine the start addresses of two or more sections. These
1300 are not support by other object file formats.
1302 @item @code{END} pseudo-op specifying start address
1304 The MRI @code{END} pseudo-op permits the specification of a start address.
1305 This is not supported by other object file formats. The start address may
1306 instead be specified using the @code{-e} option to the linker, or in a linker
1309 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1311 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1312 name to the output file. This is not supported by other object file formats.
1314 @item @code{ORG} pseudo-op
1316 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1317 address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op,
1318 which changes the location within the current section. Absolute sections are
1319 not supported by other object file formats. The address of a section may be
1320 assigned within a linker script.
1323 There are some other features of the MRI assembler which are not supported by
1324 @code{@value{AS}}, typically either because they are difficult or because they
1325 seem of little consequence. Some of these may be supported in future releases.
1329 @item EBCDIC strings
1331 EBCDIC strings are not supported.
1333 @item packed binary coded decimal
1335 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1336 and @code{DCB.P} pseudo-ops are not supported.
1338 @item @code{FEQU} pseudo-op
1340 The m68k @code{FEQU} pseudo-op is not supported.
1342 @item @code{NOOBJ} pseudo-op
1344 The m68k @code{NOOBJ} pseudo-op is not supported.
1346 @item @code{OPT} branch control options
1348 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1349 @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically
1350 relaxes all branches, whether forward or backward, to an appropriate size, so
1351 these options serve no purpose.
1353 @item @code{OPT} list control options
1355 The following m68k @code{OPT} list control options are ignored: @code{C},
1356 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1357 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1359 @item other @code{OPT} options
1361 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1362 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1364 @item @code{OPT} @code{D} option is default
1366 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1367 @code{OPT NOD} may be used to turn it off.
1369 @item @code{XREF} pseudo-op.
1371 The m68k @code{XREF} pseudo-op is ignored.
1373 @item @code{.debug} pseudo-op
1375 The i960 @code{.debug} pseudo-op is not supported.
1377 @item @code{.extended} pseudo-op
1379 The i960 @code{.extended} pseudo-op is not supported.
1381 @item @code{.list} pseudo-op.
1383 The various options of the i960 @code{.list} pseudo-op are not supported.
1385 @item @code{.optimize} pseudo-op
1387 The i960 @code{.optimize} pseudo-op is not supported.
1389 @item @code{.output} pseudo-op
1391 The i960 @code{.output} pseudo-op is not supported.
1393 @item @code{.setreal} pseudo-op
1395 The i960 @code{.setreal} pseudo-op is not supported.
1400 @section Dependency tracking: @code{--MD}
1403 @cindex dependency tracking
1406 @code{@value{AS}} can generate a dependency file for the file it creates. This
1407 file consists of a single rule suitable for @code{make} describing the
1408 dependencies of the main source file.
1410 The rule is written to the file named in its argument.
1412 This feature is used in the automatic updating of makefiles.
1415 @section Name the Object File: @code{-o}
1418 @cindex naming object file
1419 @cindex object file name
1420 There is always one object file output when you run @code{@value{AS}}. By
1421 default it has the name
1424 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1438 You use this option (which takes exactly one filename) to give the
1439 object file a different name.
1441 Whatever the object file is called, @code{@value{AS}} overwrites any
1442 existing file of the same name.
1445 @section Join Data and Text Sections: @code{-R}
1448 @cindex data and text sections, joining
1449 @cindex text and data sections, joining
1450 @cindex joining text and data sections
1451 @cindex merging text and data sections
1452 @code{-R} tells @code{@value{AS}} to write the object file as if all
1453 data-section data lives in the text section. This is only done at
1454 the very last moment: your binary data are the same, but data
1455 section parts are relocated differently. The data section part of
1456 your object file is zero bytes long because all its bytes are
1457 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1459 When you specify @code{-R} it would be possible to generate shorter
1460 address displacements (because we do not have to cross between text and
1461 data section). We refrain from doing this simply for compatibility with
1462 older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
1465 When @code{@value{AS}} is configured for COFF output,
1466 this option is only useful if you use sections named @samp{.text} and
1471 @code{-R} is not supported for any of the HPPA targets. Using
1472 @code{-R} generates a warning from @code{@value{AS}}.
1476 @section Display Assembly Statistics: @code{--statistics}
1478 @kindex --statistics
1479 @cindex statistics, about assembly
1480 @cindex time, total for assembly
1481 @cindex space used, maximum for assembly
1482 Use @samp{--statistics} to display two statistics about the resources used by
1483 @code{@value{AS}}: the maximum amount of space allocated during the assembly
1484 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1487 @node traditional-format
1488 @section Compatible output: @code{--traditional-format}
1490 @kindex --traditional-format
1491 For some targets, the output of @code{@value{AS}} is different in some ways
1492 from the output of some existing assembler. This switch requests
1493 @code{@value{AS}} to use the traditional format instead.
1495 For example, it disables the exception frame optimizations which
1496 @code{@value{AS}} normally does by default on @code{@value{GCC}} output.
1499 @section Announce Version: @code{-v}
1503 @cindex assembler version
1504 @cindex version of assembler
1505 You can find out what version of as is running by including the
1506 option @samp{-v} (which you can also spell as @samp{-version}) on the
1510 @section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings}
1512 @code{@value{AS}} should never give a warning or error message when
1513 assembling compiler output. But programs written by people often
1514 cause @code{@value{AS}} to give a warning that a particular assumption was
1515 made. All such warnings are directed to the standard error file.
1518 @kindex @samp{--no-warn}
1519 @cindex suppressing warnings
1520 @cindex warnings, suppressing
1521 If you use the @code{-W} and @code{--no-warn} options, no warnings are issued.
1522 This only affects the warning messages: it does not change any particular of
1523 how @code{@value{AS}} assembles your file. Errors, which stop the assembly,
1526 @kindex @samp{--fatal-warnings}
1527 @cindex errors, caused by warnings
1528 @cindex warnings, causing error
1529 If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers
1530 files that generate warnings to be in error.
1532 @kindex @samp{--warn}
1533 @cindex warnings, switching on
1534 You can switch these options off again by specifying @code{--warn}, which
1535 causes warnings to be output as usual.
1538 @section Generate Object File in Spite of Errors: @code{-Z}
1539 @cindex object file, after errors
1540 @cindex errors, continuing after
1541 After an error message, @code{@value{AS}} normally produces no output. If for
1542 some reason you are interested in object file output even after
1543 @code{@value{AS}} gives an error message on your program, use the @samp{-Z}
1544 option. If there are any errors, @code{@value{AS}} continues anyways, and
1545 writes an object file after a final warning message of the form @samp{@var{n}
1546 errors, @var{m} warnings, generating bad object file.}
1551 @cindex machine-independent syntax
1552 @cindex syntax, machine-independent
1553 This chapter describes the machine-independent syntax allowed in a
1554 source file. @code{@value{AS}} syntax is similar to what many other
1555 assemblers use; it is inspired by the BSD 4.2
1560 assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
1564 * Preprocessing:: Preprocessing
1565 * Whitespace:: Whitespace
1566 * Comments:: Comments
1567 * Symbol Intro:: Symbols
1568 * Statements:: Statements
1569 * Constants:: Constants
1573 @section Preprocessing
1575 @cindex preprocessing
1576 The @code{@value{AS}} internal preprocessor:
1578 @cindex whitespace, removed by preprocessor
1580 adjusts and removes extra whitespace. It leaves one space or tab before
1581 the keywords on a line, and turns any other whitespace on the line into
1584 @cindex comments, removed by preprocessor
1586 removes all comments, replacing them with a single space, or an
1587 appropriate number of newlines.
1589 @cindex constants, converted by preprocessor
1591 converts character constants into the appropriate numeric values.
1594 It does not do macro processing, include file handling, or
1595 anything else you may get from your C compiler's preprocessor. You can
1596 do include file processing with the @code{.include} directive
1597 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1598 to get other ``CPP'' style preprocessing, by giving the input file a
1599 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1600 Output, gcc.info, Using GNU CC}.
1602 Excess whitespace, comments, and character constants
1603 cannot be used in the portions of the input text that are not
1606 @cindex turning preprocessing on and off
1607 @cindex preprocessing, turning on and off
1610 If the first line of an input file is @code{#NO_APP} or if you use the
1611 @samp{-f} option, whitespace and comments are not removed from the input file.
1612 Within an input file, you can ask for whitespace and comment removal in
1613 specific portions of the by putting a line that says @code{#APP} before the
1614 text that may contain whitespace or comments, and putting a line that says
1615 @code{#NO_APP} after this text. This feature is mainly intend to support
1616 @code{asm} statements in compilers whose output is otherwise free of comments
1623 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1624 Whitespace is used to separate symbols, and to make programs neater for
1625 people to read. Unless within character constants
1626 (@pxref{Characters,,Character Constants}), any whitespace means the same
1627 as exactly one space.
1633 There are two ways of rendering comments to @code{@value{AS}}. In both
1634 cases the comment is equivalent to one space.
1636 Anything from @samp{/*} through the next @samp{*/} is a comment.
1637 This means you may not nest these comments.
1641 The only way to include a newline ('\n') in a comment
1642 is to use this sort of comment.
1645 /* This sort of comment does not nest. */
1648 @cindex line comment character
1649 Anything from the @dfn{line comment} character to the next newline
1650 is considered a comment and is ignored. The line comment character is
1652 @samp{;} for the AMD 29K family;
1655 @samp{;} on the ARC;
1658 @samp{@@} on the ARM;
1661 @samp{;} for the H8/300 family;
1664 @samp{!} for the H8/500 family;
1667 @samp{;} for the HPPA;
1670 @samp{#} on the i960;
1673 @samp{;} for picoJava;
1676 @samp{!} for the Hitachi SH;
1679 @samp{!} on the SPARC;
1682 @samp{#} on the m32r;
1685 @samp{|} on the 680x0;
1688 @samp{#} on the 68HC11 and 68HC12;
1691 @samp{#} on the Vax;
1694 @samp{!} for the Z8000;
1697 @samp{#} on the V850;
1699 see @ref{Machine Dependencies}. @refill
1700 @c FIXME What about i386, m88k, i860?
1703 On some machines there are two different line comment characters. One
1704 character only begins a comment if it is the first non-whitespace character on
1705 a line, while the other always begins a comment.
1709 The V850 assembler also supports a double dash as starting a comment that
1710 extends to the end of the line.
1716 @cindex lines starting with @code{#}
1717 @cindex logical line numbers
1718 To be compatible with past assemblers, lines that begin with @samp{#} have a
1719 special interpretation. Following the @samp{#} should be an absolute
1720 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1721 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1722 new logical file name. The rest of the line, if any, should be whitespace.
1724 If the first non-whitespace characters on the line are not numeric,
1725 the line is ignored. (Just like a comment.)
1728 # This is an ordinary comment.
1729 # 42-6 "new_file_name" # New logical file name
1730 # This is logical line # 36.
1732 This feature is deprecated, and may disappear from future versions
1733 of @code{@value{AS}}.
1738 @cindex characters used in symbols
1739 @ifclear SPECIAL-SYMS
1740 A @dfn{symbol} is one or more characters chosen from the set of all
1741 letters (both upper and lower case), digits and the three characters
1747 A @dfn{symbol} is one or more characters chosen from the set of all
1748 letters (both upper and lower case), digits and the three characters
1749 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
1755 On most machines, you can also use @code{$} in symbol names; exceptions
1756 are noted in @ref{Machine Dependencies}.
1758 No symbol may begin with a digit. Case is significant.
1759 There is no length limit: all characters are significant. Symbols are
1760 delimited by characters not in that set, or by the beginning of a file
1761 (since the source program must end with a newline, the end of a file is
1762 not a possible symbol delimiter). @xref{Symbols}.
1763 @cindex length of symbols
1768 @cindex statements, structure of
1769 @cindex line separator character
1770 @cindex statement separator character
1772 @ifclear abnormal-separator
1773 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
1774 semicolon (@samp{;}). The newline or semicolon is considered part of
1775 the preceding statement. Newlines and semicolons within character
1776 constants are an exception: they do not end statements.
1778 @ifset abnormal-separator
1780 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
1781 sign (@samp{@@}). The newline or at sign is considered part of the
1782 preceding statement. Newlines and at signs within character constants
1783 are an exception: they do not end statements.
1786 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
1787 point (@samp{!}). The newline or exclamation point is considered part of the
1788 preceding statement. Newlines and exclamation points within character
1789 constants are an exception: they do not end statements.
1792 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
1793 H8/300) a dollar sign (@samp{$}); or (for the
1796 (@samp{;}). The newline or separator character is considered part of
1797 the preceding statement. Newlines and separators within character
1798 constants are an exception: they do not end statements.
1803 A @dfn{statement} ends at a newline character (@samp{\n}) or line
1804 separator character. (The line separator is usually @samp{;}, unless
1805 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
1806 newline or separator character is considered part of the preceding
1807 statement. Newlines and separators within character constants are an
1808 exception: they do not end statements.
1811 @cindex newline, required at file end
1812 @cindex EOF, newline must precede
1813 It is an error to end any statement with end-of-file: the last
1814 character of any input file should be a newline.@refill
1816 An empty statement is allowed, and may include whitespace. It is ignored.
1818 @cindex instructions and directives
1819 @cindex directives and instructions
1820 @c "key symbol" is not used elsewhere in the document; seems pedantic to
1821 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
1823 A statement begins with zero or more labels, optionally followed by a
1824 key symbol which determines what kind of statement it is. The key
1825 symbol determines the syntax of the rest of the statement. If the
1826 symbol begins with a dot @samp{.} then the statement is an assembler
1827 directive: typically valid for any computer. If the symbol begins with
1828 a letter the statement is an assembly language @dfn{instruction}: it
1829 assembles into a machine language instruction.
1831 Different versions of @code{@value{AS}} for different computers
1832 recognize different instructions. In fact, the same symbol may
1833 represent a different instruction in a different computer's assembly
1837 @cindex @code{:} (label)
1838 @cindex label (@code{:})
1839 A label is a symbol immediately followed by a colon (@code{:}).
1840 Whitespace before a label or after a colon is permitted, but you may not
1841 have whitespace between a label's symbol and its colon. @xref{Labels}.
1844 For HPPA targets, labels need not be immediately followed by a colon, but
1845 the definition of a label must begin in column zero. This also implies that
1846 only one label may be defined on each line.
1850 label: .directive followed by something
1851 another_label: # This is an empty statement.
1852 instruction operand_1, operand_2, @dots{}
1859 A constant is a number, written so that its value is known by
1860 inspection, without knowing any context. Like this:
1863 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
1864 .ascii "Ring the bell\7" # A string constant.
1865 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
1866 .float 0f-314159265358979323846264338327\
1867 95028841971.693993751E-40 # - pi, a flonum.
1872 * Characters:: Character Constants
1873 * Numbers:: Number Constants
1877 @subsection Character Constants
1879 @cindex character constants
1880 @cindex constants, character
1881 There are two kinds of character constants. A @dfn{character} stands
1882 for one character in one byte and its value may be used in
1883 numeric expressions. String constants (properly called string
1884 @emph{literals}) are potentially many bytes and their values may not be
1885 used in arithmetic expressions.
1889 * Chars:: Characters
1893 @subsubsection Strings
1895 @cindex string constants
1896 @cindex constants, string
1897 A @dfn{string} is written between double-quotes. It may contain
1898 double-quotes or null characters. The way to get special characters
1899 into a string is to @dfn{escape} these characters: precede them with
1900 a backslash @samp{\} character. For example @samp{\\} represents
1901 one backslash: the first @code{\} is an escape which tells
1902 @code{@value{AS}} to interpret the second character literally as a backslash
1903 (which prevents @code{@value{AS}} from recognizing the second @code{\} as an
1904 escape character). The complete list of escapes follows.
1906 @cindex escape codes, character
1907 @cindex character escape codes
1910 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
1912 @cindex @code{\b} (backspace character)
1913 @cindex backspace (@code{\b})
1915 Mnemonic for backspace; for ASCII this is octal code 010.
1918 @c Mnemonic for EOText; for ASCII this is octal code 004.
1920 @cindex @code{\f} (formfeed character)
1921 @cindex formfeed (@code{\f})
1923 Mnemonic for FormFeed; for ASCII this is octal code 014.
1925 @cindex @code{\n} (newline character)
1926 @cindex newline (@code{\n})
1928 Mnemonic for newline; for ASCII this is octal code 012.
1931 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
1933 @cindex @code{\r} (carriage return character)
1934 @cindex carriage return (@code{\r})
1936 Mnemonic for carriage-Return; for ASCII this is octal code 015.
1939 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
1940 @c other assemblers.
1942 @cindex @code{\t} (tab)
1943 @cindex tab (@code{\t})
1945 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
1948 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
1949 @c @item \x @var{digit} @var{digit} @var{digit}
1950 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
1952 @cindex @code{\@var{ddd}} (octal character code)
1953 @cindex octal character code (@code{\@var{ddd}})
1954 @item \ @var{digit} @var{digit} @var{digit}
1955 An octal character code. The numeric code is 3 octal digits.
1956 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
1957 for example, @code{\008} has the value 010, and @code{\009} the value 011.
1959 @cindex @code{\@var{xd...}} (hex character code)
1960 @cindex hex character code (@code{\@var{xd...}})
1961 @item \@code{x} @var{hex-digits...}
1962 A hex character code. All trailing hex digits are combined. Either upper or
1963 lower case @code{x} works.
1965 @cindex @code{\\} (@samp{\} character)
1966 @cindex backslash (@code{\\})
1968 Represents one @samp{\} character.
1971 @c Represents one @samp{'} (accent acute) character.
1972 @c This is needed in single character literals
1973 @c (@xref{Characters,,Character Constants}.) to represent
1976 @cindex @code{\"} (doublequote character)
1977 @cindex doublequote (@code{\"})
1979 Represents one @samp{"} character. Needed in strings to represent
1980 this character, because an unescaped @samp{"} would end the string.
1982 @item \ @var{anything-else}
1983 Any other character when escaped by @kbd{\} gives a warning, but
1984 assembles as if the @samp{\} was not present. The idea is that if
1985 you used an escape sequence you clearly didn't want the literal
1986 interpretation of the following character. However @code{@value{AS}} has no
1987 other interpretation, so @code{@value{AS}} knows it is giving you the wrong
1988 code and warns you of the fact.
1991 Which characters are escapable, and what those escapes represent,
1992 varies widely among assemblers. The current set is what we think
1993 the BSD 4.2 assembler recognizes, and is a subset of what most C
1994 compilers recognize. If you are in doubt, do not use an escape
1998 @subsubsection Characters
2000 @cindex single character constant
2001 @cindex character, single
2002 @cindex constant, single character
2003 A single character may be written as a single quote immediately
2004 followed by that character. The same escapes apply to characters as
2005 to strings. So if you want to write the character backslash, you
2006 must write @kbd{'\\} where the first @code{\} escapes the second
2007 @code{\}. As you can see, the quote is an acute accent, not a
2008 grave accent. A newline
2010 @ifclear abnormal-separator
2011 (or semicolon @samp{;})
2013 @ifset abnormal-separator
2015 (or at sign @samp{@@})
2018 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2024 immediately following an acute accent is taken as a literal character
2025 and does not count as the end of a statement. The value of a character
2026 constant in a numeric expression is the machine's byte-wide code for
2027 that character. @code{@value{AS}} assumes your character code is ASCII:
2028 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2031 @subsection Number Constants
2033 @cindex constants, number
2034 @cindex number constants
2035 @code{@value{AS}} distinguishes three kinds of numbers according to how they
2036 are stored in the target machine. @emph{Integers} are numbers that
2037 would fit into an @code{int} in the C language. @emph{Bignums} are
2038 integers, but they are stored in more than 32 bits. @emph{Flonums}
2039 are floating point numbers, described below.
2042 * Integers:: Integers
2047 * Bit Fields:: Bit Fields
2053 @subsubsection Integers
2055 @cindex constants, integer
2057 @cindex binary integers
2058 @cindex integers, binary
2059 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2060 the binary digits @samp{01}.
2062 @cindex octal integers
2063 @cindex integers, octal
2064 An octal integer is @samp{0} followed by zero or more of the octal
2065 digits (@samp{01234567}).
2067 @cindex decimal integers
2068 @cindex integers, decimal
2069 A decimal integer starts with a non-zero digit followed by zero or
2070 more digits (@samp{0123456789}).
2072 @cindex hexadecimal integers
2073 @cindex integers, hexadecimal
2074 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2075 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2077 Integers have the usual values. To denote a negative integer, use
2078 the prefix operator @samp{-} discussed under expressions
2079 (@pxref{Prefix Ops,,Prefix Operators}).
2082 @subsubsection Bignums
2085 @cindex constants, bignum
2086 A @dfn{bignum} has the same syntax and semantics as an integer
2087 except that the number (or its negative) takes more than 32 bits to
2088 represent in binary. The distinction is made because in some places
2089 integers are permitted while bignums are not.
2092 @subsubsection Flonums
2094 @cindex floating point numbers
2095 @cindex constants, floating point
2097 @cindex precision, floating point
2098 A @dfn{flonum} represents a floating point number. The translation is
2099 indirect: a decimal floating point number from the text is converted by
2100 @code{@value{AS}} to a generic binary floating point number of more than
2101 sufficient precision. This generic floating point number is converted
2102 to a particular computer's floating point format (or formats) by a
2103 portion of @code{@value{AS}} specialized to that computer.
2105 A flonum is written by writing (in order)
2110 (@samp{0} is optional on the HPPA.)
2114 A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
2116 @kbd{e} is recommended. Case is not important.
2118 @c FIXME: verify if flonum syntax really this vague for most cases
2119 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2120 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2123 On the H8/300, H8/500,
2125 and AMD 29K architectures, the letter must be
2126 one of the letters @samp{DFPRSX} (in upper or lower case).
2128 On the ARC, the letter must be one of the letters @samp{DFRS}
2129 (in upper or lower case).
2131 On the Intel 960 architecture, the letter must be
2132 one of the letters @samp{DFT} (in upper or lower case).
2134 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2138 One of the letters @samp{DFPRSX} (in upper or lower case).
2141 One of the letters @samp{DFRS} (in upper or lower case).
2144 One of the letters @samp{DFPRSX} (in upper or lower case).
2147 The letter @samp{E} (upper case only).
2150 One of the letters @samp{DFT} (in upper or lower case).
2155 An optional sign: either @samp{+} or @samp{-}.
2158 An optional @dfn{integer part}: zero or more decimal digits.
2161 An optional @dfn{fractional part}: @samp{.} followed by zero
2162 or more decimal digits.
2165 An optional exponent, consisting of:
2169 An @samp{E} or @samp{e}.
2170 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2171 @c principle this can perfectly well be different on different targets.
2173 Optional sign: either @samp{+} or @samp{-}.
2175 One or more decimal digits.
2180 At least one of the integer part or the fractional part must be
2181 present. The floating point number has the usual base-10 value.
2183 @code{@value{AS}} does all processing using integers. Flonums are computed
2184 independently of any floating point hardware in the computer running
2189 @c Bit fields are written as a general facility but are also controlled
2190 @c by a conditional-compilation flag---which is as of now (21mar91)
2191 @c turned on only by the i960 config of GAS.
2193 @subsubsection Bit Fields
2196 @cindex constants, bit field
2197 You can also define numeric constants as @dfn{bit fields}.
2198 specify two numbers separated by a colon---
2200 @var{mask}:@var{value}
2203 @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2206 The resulting number is then packed
2208 @c this conditional paren in case bit fields turned on elsewhere than 960
2209 (in host-dependent byte order)
2211 into a field whose width depends on which assembler directive has the
2212 bit-field as its argument. Overflow (a result from the bitwise and
2213 requiring more binary digits to represent) is not an error; instead,
2214 more constants are generated, of the specified width, beginning with the
2215 least significant digits.@refill
2217 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2218 @code{.short}, and @code{.word} accept bit-field arguments.
2223 @chapter Sections and Relocation
2228 * Secs Background:: Background
2229 * Ld Sections:: Linker Sections
2230 * As Sections:: Assembler Internal Sections
2231 * Sub-Sections:: Sub-Sections
2235 @node Secs Background
2238 Roughly, a section is a range of addresses, with no gaps; all data
2239 ``in'' those addresses is treated the same for some particular purpose.
2240 For example there may be a ``read only'' section.
2242 @cindex linker, and assembler
2243 @cindex assembler, and linker
2244 The linker @code{@value{LD}} reads many object files (partial programs) and
2245 combines their contents to form a runnable program. When @code{@value{AS}}
2246 emits an object file, the partial program is assumed to start at address 0.
2247 @code{@value{LD}} assigns the final addresses for the partial program, so that
2248 different partial programs do not overlap. This is actually an
2249 oversimplification, but it suffices to explain how @code{@value{AS}} uses
2252 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2253 addresses. These blocks slide to their run-time addresses as rigid
2254 units; their length does not change and neither does the order of bytes
2255 within them. Such a rigid unit is called a @emph{section}. Assigning
2256 run-time addresses to sections is called @dfn{relocation}. It includes
2257 the task of adjusting mentions of object-file addresses so they refer to
2258 the proper run-time addresses.
2260 For the H8/300 and H8/500,
2261 and for the Hitachi SH,
2262 @code{@value{AS}} pads sections if needed to
2263 ensure they end on a word (sixteen bit) boundary.
2266 @cindex standard assembler sections
2267 An object file written by @code{@value{AS}} has at least three sections, any
2268 of which may be empty. These are named @dfn{text}, @dfn{data} and
2273 When it generates COFF output,
2275 @code{@value{AS}} can also generate whatever other named sections you specify
2276 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2277 If you do not use any directives that place output in the @samp{.text}
2278 or @samp{.data} sections, these sections still exist, but are empty.
2283 When @code{@value{AS}} generates SOM or ELF output for the HPPA,
2285 @code{@value{AS}} can also generate whatever other named sections you
2286 specify using the @samp{.space} and @samp{.subspace} directives. See
2287 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2288 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2289 assembler directives.
2292 Additionally, @code{@value{AS}} uses different names for the standard
2293 text, data, and bss sections when generating SOM output. Program text
2294 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2295 BSS into @samp{$BSS$}.
2299 Within the object file, the text section starts at address @code{0}, the
2300 data section follows, and the bss section follows the data section.
2303 When generating either SOM or ELF output files on the HPPA, the text
2304 section starts at address @code{0}, the data section at address
2305 @code{0x4000000}, and the bss section follows the data section.
2308 To let @code{@value{LD}} know which data changes when the sections are
2309 relocated, and how to change that data, @code{@value{AS}} also writes to the
2310 object file details of the relocation needed. To perform relocation
2311 @code{@value{LD}} must know, each time an address in the object
2315 Where in the object file is the beginning of this reference to
2318 How long (in bytes) is this reference?
2320 Which section does the address refer to? What is the numeric value of
2322 (@var{address}) @minus{} (@var{start-address of section})?
2325 Is the reference to an address ``Program-Counter relative''?
2328 @cindex addresses, format of
2329 @cindex section-relative addressing
2330 In fact, every address @code{@value{AS}} ever uses is expressed as
2332 (@var{section}) + (@var{offset into section})
2335 Further, most expressions @code{@value{AS}} computes have this section-relative
2338 (For some object formats, such as SOM for the HPPA, some expressions are
2339 symbol-relative instead.)
2342 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2343 @var{N} into section @var{secname}.''
2345 Apart from text, data and bss sections you need to know about the
2346 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2347 addresses in the absolute section remain unchanged. For example, address
2348 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2349 @code{@value{LD}}. Although the linker never arranges two partial programs'
2350 data sections with overlapping addresses after linking, @emph{by definition}
2351 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2352 part of a program is always the same address when the program is running as
2353 address @code{@{absolute@ 239@}} in any other part of the program.
2355 The idea of sections is extended to the @dfn{undefined} section. Any
2356 address whose section is unknown at assembly time is by definition
2357 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2358 Since numbers are always defined, the only way to generate an undefined
2359 address is to mention an undefined symbol. A reference to a named
2360 common block would be such a symbol: its value is unknown at assembly
2361 time so it has section @emph{undefined}.
2363 By analogy the word @emph{section} is used to describe groups of sections in
2364 the linked program. @code{@value{LD}} puts all partial programs' text
2365 sections in contiguous addresses in the linked program. It is
2366 customary to refer to the @emph{text section} of a program, meaning all
2367 the addresses of all partial programs' text sections. Likewise for
2368 data and bss sections.
2370 Some sections are manipulated by @code{@value{LD}}; others are invented for
2371 use of @code{@value{AS}} and have no meaning except during assembly.
2374 @section Linker Sections
2375 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2380 @cindex named sections
2381 @cindex sections, named
2382 @item named sections
2385 @cindex text section
2386 @cindex data section
2390 These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
2391 separate but equal sections. Anything you can say of one section is
2394 When the program is running, however, it is
2395 customary for the text section to be unalterable. The
2396 text section is often shared among processes: it contains
2397 instructions, constants and the like. The data section of a running
2398 program is usually alterable: for example, C variables would be stored
2399 in the data section.
2404 This section contains zeroed bytes when your program begins running. It
2405 is used to hold unitialized variables or common storage. The length of
2406 each partial program's bss section is important, but because it starts
2407 out containing zeroed bytes there is no need to store explicit zero
2408 bytes in the object file. The bss section was invented to eliminate
2409 those explicit zeros from object files.
2411 @cindex absolute section
2412 @item absolute section
2413 Address 0 of this section is always ``relocated'' to runtime address 0.
2414 This is useful if you want to refer to an address that @code{@value{LD}} must
2415 not change when relocating. In this sense we speak of absolute
2416 addresses being ``unrelocatable'': they do not change during relocation.
2418 @cindex undefined section
2419 @item undefined section
2420 This ``section'' is a catch-all for address references to objects not in
2421 the preceding sections.
2422 @c FIXME: ref to some other doc on obj-file formats could go here.
2425 @cindex relocation example
2426 An idealized example of three relocatable sections follows.
2428 The example uses the traditional section names @samp{.text} and @samp{.data}.
2430 Memory addresses are on the horizontal axis.
2434 @c END TEXI2ROFF-KILL
2437 partial program # 1: |ttttt|dddd|00|
2444 partial program # 2: |TTT|DDD|000|
2447 +--+---+-----+--+----+---+-----+~~
2448 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2449 +--+---+-----+--+----+---+-----+~~
2451 addresses: 0 @dots{}
2458 \line{\it Partial program \#1: \hfil}
2459 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2460 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2462 \line{\it Partial program \#2: \hfil}
2463 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2464 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2466 \line{\it linked program: \hfil}
2467 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2468 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2469 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2470 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2472 \line{\it addresses: \hfil}
2476 @c END TEXI2ROFF-KILL
2479 @section Assembler Internal Sections
2481 @cindex internal assembler sections
2482 @cindex sections in messages, internal
2483 These sections are meant only for the internal use of @code{@value{AS}}. They
2484 have no meaning at run-time. You do not really need to know about these
2485 sections for most purposes; but they can be mentioned in @code{@value{AS}}
2486 warning messages, so it might be helpful to have an idea of their
2487 meanings to @code{@value{AS}}. These sections are used to permit the
2488 value of every expression in your assembly language program to be a
2489 section-relative address.
2492 @cindex assembler internal logic error
2493 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2494 An internal assembler logic error has been found. This means there is a
2495 bug in the assembler.
2497 @cindex expr (internal section)
2499 The assembler stores complex expression internally as combinations of
2500 symbols. When it needs to represent an expression as a symbol, it puts
2501 it in the expr section.
2503 @c FIXME item transfer[t] vector preload
2504 @c FIXME item transfer[t] vector postload
2505 @c FIXME item register
2509 @section Sub-Sections
2511 @cindex numbered subsections
2512 @cindex grouping data
2518 fall into two sections: text and data.
2520 You may have separate groups of
2522 data in named sections
2526 data in named sections
2532 that you want to end up near to each other in the object file, even though they
2533 are not contiguous in the assembler source. @code{@value{AS}} allows you to
2534 use @dfn{subsections} for this purpose. Within each section, there can be
2535 numbered subsections with values from 0 to 8192. Objects assembled into the
2536 same subsection go into the object file together with other objects in the same
2537 subsection. For example, a compiler might want to store constants in the text
2538 section, but might not want to have them interspersed with the program being
2539 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2540 section of code being output, and a @samp{.text 1} before each group of
2541 constants being output.
2543 Subsections are optional. If you do not use subsections, everything
2544 goes in subsection number zero.
2547 Each subsection is zero-padded up to a multiple of four bytes.
2548 (Subsections may be padded a different amount on different flavors
2549 of @code{@value{AS}}.)
2553 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2554 boundary (two bytes).
2555 The same is true on the Hitachi SH.
2558 @c FIXME section padding (alignment)?
2559 @c Rich Pixley says padding here depends on target obj code format; that
2560 @c doesn't seem particularly useful to say without further elaboration,
2561 @c so for now I say nothing about it. If this is a generic BFD issue,
2562 @c these paragraphs might need to vanish from this manual, and be
2563 @c discussed in BFD chapter of binutils (or some such).
2566 On the AMD 29K family, no particular padding is added to section or
2567 subsection sizes; @value{AS} forces no alignment on this platform.
2571 Subsections appear in your object file in numeric order, lowest numbered
2572 to highest. (All this to be compatible with other people's assemblers.)
2573 The object file contains no representation of subsections; @code{@value{LD}} and
2574 other programs that manipulate object files see no trace of them.
2575 They just see all your text subsections as a text section, and all your
2576 data subsections as a data section.
2578 To specify which subsection you want subsequent statements assembled
2579 into, use a numeric argument to specify it, in a @samp{.text
2580 @var{expression}} or a @samp{.data @var{expression}} statement.
2583 When generating COFF output, you
2588 can also use an extra subsection
2589 argument with arbitrary named sections: @samp{.section @var{name},
2592 @var{Expression} should be an absolute expression.
2593 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2594 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2595 begins in @code{text 0}. For instance:
2597 .text 0 # The default subsection is text 0 anyway.
2598 .ascii "This lives in the first text subsection. *"
2600 .ascii "But this lives in the second text subsection."
2602 .ascii "This lives in the data section,"
2603 .ascii "in the first data subsection."
2605 .ascii "This lives in the first text section,"
2606 .ascii "immediately following the asterisk (*)."
2609 Each section has a @dfn{location counter} incremented by one for every byte
2610 assembled into that section. Because subsections are merely a convenience
2611 restricted to @code{@value{AS}} there is no concept of a subsection location
2612 counter. There is no way to directly manipulate a location counter---but the
2613 @code{.align} directive changes it, and any label definition captures its
2614 current value. The location counter of the section where statements are being
2615 assembled is said to be the @dfn{active} location counter.
2618 @section bss Section
2621 @cindex common variable storage
2622 The bss section is used for local common variable storage.
2623 You may allocate address space in the bss section, but you may
2624 not dictate data to load into it before your program executes. When
2625 your program starts running, all the contents of the bss
2626 section are zeroed bytes.
2628 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2629 @ref{Lcomm,,@code{.lcomm}}.
2631 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2632 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2635 When assembling for a target which supports multiple sections, such as ELF or
2636 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2637 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2638 section. Typically the section will only contain symbol definitions and
2639 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2646 Symbols are a central concept: the programmer uses symbols to name
2647 things, the linker uses symbols to link, and the debugger uses symbols
2651 @cindex debuggers, and symbol order
2652 @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
2653 the same order they were declared. This may break some debuggers.
2658 * Setting Symbols:: Giving Symbols Other Values
2659 * Symbol Names:: Symbol Names
2660 * Dot:: The Special Dot Symbol
2661 * Symbol Attributes:: Symbol Attributes
2668 A @dfn{label} is written as a symbol immediately followed by a colon
2669 @samp{:}. The symbol then represents the current value of the
2670 active location counter, and is, for example, a suitable instruction
2671 operand. You are warned if you use the same symbol to represent two
2672 different locations: the first definition overrides any other
2676 On the HPPA, the usual form for a label need not be immediately followed by a
2677 colon, but instead must start in column zero. Only one label may be defined on
2678 a single line. To work around this, the HPPA version of @code{@value{AS}} also
2679 provides a special directive @code{.label} for defining labels more flexibly.
2682 @node Setting Symbols
2683 @section Giving Symbols Other Values
2685 @cindex assigning values to symbols
2686 @cindex symbol values, assigning
2687 A symbol can be given an arbitrary value by writing a symbol, followed
2688 by an equals sign @samp{=}, followed by an expression
2689 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2690 directive. @xref{Set,,@code{.set}}.
2693 @section Symbol Names
2695 @cindex symbol names
2696 @cindex names, symbol
2697 @ifclear SPECIAL-SYMS
2698 Symbol names begin with a letter or with one of @samp{._}. On most
2699 machines, you can also use @code{$} in symbol names; exceptions are
2700 noted in @ref{Machine Dependencies}. That character may be followed by any
2701 string of digits, letters, dollar signs (unless otherwise noted in
2702 @ref{Machine Dependencies}), and underscores.
2705 For the AMD 29K family, @samp{?} is also allowed in the
2706 body of a symbol name, though not at its beginning.
2711 Symbol names begin with a letter or with one of @samp{._}. On the
2713 H8/500, you can also use @code{$} in symbol names. That character may
2714 be followed by any string of digits, letters, dollar signs (save on the
2715 H8/300), and underscores.
2719 Case of letters is significant: @code{foo} is a different symbol name
2722 Each symbol has exactly one name. Each name in an assembly language program
2723 refers to exactly one symbol. You may use that symbol name any number of times
2726 @subheading Local Symbol Names
2728 @cindex local symbol names
2729 @cindex symbol names, local
2730 @cindex temporary symbol names
2731 @cindex symbol names, temporary
2732 Local symbols help compilers and programmers use names temporarily.
2733 There are ten local symbol names, which are re-used throughout the
2734 program. You may refer to them using the names @samp{0} @samp{1}
2735 @dots{} @samp{9}. To define a local symbol, write a label of the form
2736 @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
2737 recent previous definition of that symbol write @samp{@b{N}b}, using the
2738 same digit as when you defined the label. To refer to the next
2739 definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
2740 a choice of 10 forward references. The @samp{b} stands for
2741 ``backwards'' and the @samp{f} stands for ``forwards''.
2743 Local symbols are not emitted by the current @sc{gnu} C compiler.
2745 There is no restriction on how you can use these labels, but
2746 remember that at any point in the assembly you can refer to at most
2747 10 prior local labels and to at most 10 forward local labels.
2749 Local symbol names are only a notation device. They are immediately
2750 transformed into more conventional symbol names before the assembler
2751 uses them. The symbol names stored in the symbol table, appearing in
2752 error messages and optionally emitted to the object file have these
2757 All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
2758 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
2759 used for symbols you are never intended to see. If you use the
2760 @samp{-L} option then @code{@value{AS}} retains these symbols in the
2761 object file. If you also instruct @code{@value{LD}} to retain these symbols,
2762 you may use them in debugging.
2765 If the label is written @samp{0:} then the digit is @samp{0}.
2766 If the label is written @samp{1:} then the digit is @samp{1}.
2767 And so on up through @samp{9:}.
2770 This unusual character is included so you do not accidentally invent
2771 a symbol of the same name. The character has ASCII value
2774 @item @emph{ordinal number}
2775 This is a serial number to keep the labels distinct. The first
2776 @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
2777 number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
2781 For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th
2782 @code{3:} is named @code{L3@kbd{C-A}44}.
2785 @section The Special Dot Symbol
2787 @cindex dot (symbol)
2788 @cindex @code{.} (symbol)
2789 @cindex current address
2790 @cindex location counter
2791 The special symbol @samp{.} refers to the current address that
2792 @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
2793 .long .} defines @code{melvin} to contain its own address.
2794 Assigning a value to @code{.} is treated the same as a @code{.org}
2795 directive. Thus, the expression @samp{.=.+4} is the same as saying
2796 @ifclear no-space-dir
2805 @node Symbol Attributes
2806 @section Symbol Attributes
2808 @cindex symbol attributes
2809 @cindex attributes, symbol
2810 Every symbol has, as well as its name, the attributes ``Value'' and
2811 ``Type''. Depending on output format, symbols can also have auxiliary
2814 The detailed definitions are in @file{a.out.h}.
2817 If you use a symbol without defining it, @code{@value{AS}} assumes zero for
2818 all these attributes, and probably won't warn you. This makes the
2819 symbol an externally defined symbol, which is generally what you
2823 * Symbol Value:: Value
2824 * Symbol Type:: Type
2827 * a.out Symbols:: Symbol Attributes: @code{a.out}
2831 * a.out Symbols:: Symbol Attributes: @code{a.out}
2834 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
2839 * COFF Symbols:: Symbol Attributes for COFF
2842 * SOM Symbols:: Symbol Attributes for SOM
2849 @cindex value of a symbol
2850 @cindex symbol value
2851 The value of a symbol is (usually) 32 bits. For a symbol which labels a
2852 location in the text, data, bss or absolute sections the value is the
2853 number of addresses from the start of that section to the label.
2854 Naturally for text, data and bss sections the value of a symbol changes
2855 as @code{@value{LD}} changes section base addresses during linking. Absolute
2856 symbols' values do not change during linking: that is why they are
2859 The value of an undefined symbol is treated in a special way. If it is
2860 0 then the symbol is not defined in this assembler source file, and
2861 @code{@value{LD}} tries to determine its value from other files linked into the
2862 same program. You make this kind of symbol simply by mentioning a symbol
2863 name without defining it. A non-zero value represents a @code{.comm}
2864 common declaration. The value is how much common storage to reserve, in
2865 bytes (addresses). The symbol refers to the first address of the
2871 @cindex type of a symbol
2873 The type attribute of a symbol contains relocation (section)
2874 information, any flag settings indicating that a symbol is external, and
2875 (optionally), other information for linkers and debuggers. The exact
2876 format depends on the object-code output format in use.
2881 @c The following avoids a "widow" subsection title. @group would be
2882 @c better if it were available outside examples.
2885 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
2887 @cindex @code{b.out} symbol attributes
2888 @cindex symbol attributes, @code{b.out}
2889 These symbol attributes appear only when @code{@value{AS}} is configured for
2890 one of the Berkeley-descended object output formats---@code{a.out} or
2896 @subsection Symbol Attributes: @code{a.out}
2898 @cindex @code{a.out} symbol attributes
2899 @cindex symbol attributes, @code{a.out}
2905 @subsection Symbol Attributes: @code{a.out}
2907 @cindex @code{a.out} symbol attributes
2908 @cindex symbol attributes, @code{a.out}
2912 * Symbol Desc:: Descriptor
2913 * Symbol Other:: Other
2917 @subsubsection Descriptor
2919 @cindex descriptor, of @code{a.out} symbol
2920 This is an arbitrary 16-bit value. You may establish a symbol's
2921 descriptor value by using a @code{.desc} statement
2922 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
2926 @subsubsection Other
2928 @cindex other attribute, of @code{a.out} symbol
2929 This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
2934 @subsection Symbol Attributes for COFF
2936 @cindex COFF symbol attributes
2937 @cindex symbol attributes, COFF
2939 The COFF format supports a multitude of auxiliary symbol attributes;
2940 like the primary symbol attributes, they are set between @code{.def} and
2941 @code{.endef} directives.
2943 @subsubsection Primary Attributes
2945 @cindex primary attributes, COFF symbols
2946 The symbol name is set with @code{.def}; the value and type,
2947 respectively, with @code{.val} and @code{.type}.
2949 @subsubsection Auxiliary Attributes
2951 @cindex auxiliary attributes, COFF symbols
2952 The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
2953 @code{.size}, and @code{.tag} can generate auxiliary symbol table
2954 information for COFF.
2959 @subsection Symbol Attributes for SOM
2961 @cindex SOM symbol attributes
2962 @cindex symbol attributes, SOM
2964 The SOM format for the HPPA supports a multitude of symbol attributes set with
2965 the @code{.EXPORT} and @code{.IMPORT} directives.
2967 The attributes are described in @cite{HP9000 Series 800 Assembly
2968 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
2969 @code{EXPORT} assembler directive documentation.
2973 @chapter Expressions
2977 @cindex numeric values
2978 An @dfn{expression} specifies an address or numeric value.
2979 Whitespace may precede and/or follow an expression.
2981 The result of an expression must be an absolute number, or else an offset into
2982 a particular section. If an expression is not absolute, and there is not
2983 enough information when @code{@value{AS}} sees the expression to know its
2984 section, a second pass over the source program might be necessary to interpret
2985 the expression---but the second pass is currently not implemented.
2986 @code{@value{AS}} aborts with an error message in this situation.
2989 * Empty Exprs:: Empty Expressions
2990 * Integer Exprs:: Integer Expressions
2994 @section Empty Expressions
2996 @cindex empty expressions
2997 @cindex expressions, empty
2998 An empty expression has no value: it is just whitespace or null.
2999 Wherever an absolute expression is required, you may omit the
3000 expression, and @code{@value{AS}} assumes a value of (absolute) 0. This
3001 is compatible with other assemblers.
3004 @section Integer Expressions
3006 @cindex integer expressions
3007 @cindex expressions, integer
3008 An @dfn{integer expression} is one or more @emph{arguments} delimited
3009 by @emph{operators}.
3012 * Arguments:: Arguments
3013 * Operators:: Operators
3014 * Prefix Ops:: Prefix Operators
3015 * Infix Ops:: Infix Operators
3019 @subsection Arguments
3021 @cindex expression arguments
3022 @cindex arguments in expressions
3023 @cindex operands in expressions
3024 @cindex arithmetic operands
3025 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3026 contexts arguments are sometimes called ``arithmetic operands''. In
3027 this manual, to avoid confusing them with the ``instruction operands'' of
3028 the machine language, we use the term ``argument'' to refer to parts of
3029 expressions only, reserving the word ``operand'' to refer only to machine
3030 instruction operands.
3032 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3033 @var{section} is one of text, data, bss, absolute,
3034 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3037 Numbers are usually integers.
3039 A number can be a flonum or bignum. In this case, you are warned
3040 that only the low order 32 bits are used, and @code{@value{AS}} pretends
3041 these 32 bits are an integer. You may write integer-manipulating
3042 instructions that act on exotic constants, compatible with other
3045 @cindex subexpressions
3046 Subexpressions are a left parenthesis @samp{(} followed by an integer
3047 expression, followed by a right parenthesis @samp{)}; or a prefix
3048 operator followed by an argument.
3051 @subsection Operators
3053 @cindex operators, in expressions
3054 @cindex arithmetic functions
3055 @cindex functions, in expressions
3056 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3057 operators are followed by an argument. Infix operators appear
3058 between their arguments. Operators may be preceded and/or followed by
3062 @subsection Prefix Operator
3064 @cindex prefix operators
3065 @code{@value{AS}} has the following @dfn{prefix operators}. They each take
3066 one argument, which must be absolute.
3068 @c the tex/end tex stuff surrounding this small table is meant to make
3069 @c it align, on the printed page, with the similar table in the next
3070 @c section (which is inside an enumerate).
3072 \global\advance\leftskip by \itemindent
3077 @dfn{Negation}. Two's complement negation.
3079 @dfn{Complementation}. Bitwise not.
3083 \global\advance\leftskip by -\itemindent
3087 @subsection Infix Operators
3089 @cindex infix operators
3090 @cindex operators, permitted arguments
3091 @dfn{Infix operators} take two arguments, one on either side. Operators
3092 have precedence, but operations with equal precedence are performed left
3093 to right. Apart from @code{+} or @code{-}, both arguments must be
3094 absolute, and the result is absolute.
3097 @cindex operator precedence
3098 @cindex precedence of operators
3105 @dfn{Multiplication}.
3108 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3115 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3119 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3123 Intermediate precedence
3128 @dfn{Bitwise Inclusive Or}.
3134 @dfn{Bitwise Exclusive Or}.
3137 @dfn{Bitwise Or Not}.
3144 @cindex addition, permitted arguments
3145 @cindex plus, permitted arguments
3146 @cindex arguments for addition
3148 @dfn{Addition}. If either argument is absolute, the result has the section of
3149 the other argument. You may not add together arguments from different
3152 @cindex subtraction, permitted arguments
3153 @cindex minus, permitted arguments
3154 @cindex arguments for subtraction
3156 @dfn{Subtraction}. If the right argument is absolute, the
3157 result has the section of the left argument.
3158 If both arguments are in the same section, the result is absolute.
3159 You may not subtract arguments from different sections.
3160 @c FIXME is there still something useful to say about undefined - undefined ?
3164 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3165 address; you can only have a defined section in one of the two arguments.
3168 @chapter Assembler Directives
3170 @cindex directives, machine independent
3171 @cindex pseudo-ops, machine independent
3172 @cindex machine independent directives
3173 All assembler directives have names that begin with a period (@samp{.}).
3174 The rest of the name is letters, usually in lower case.
3176 This chapter discusses directives that are available regardless of the
3177 target machine configuration for the @sc{gnu} assembler.
3179 Some machine configurations provide additional directives.
3180 @xref{Machine Dependencies}.
3183 @ifset machine-directives
3184 @xref{Machine Dependencies} for additional directives.
3189 * Abort:: @code{.abort}
3191 * ABORT:: @code{.ABORT}
3194 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3195 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3196 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3197 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3198 * Byte:: @code{.byte @var{expressions}}
3199 * Comm:: @code{.comm @var{symbol} , @var{length} }
3200 * Data:: @code{.data @var{subsection}}
3202 * Def:: @code{.def @var{name}}
3205 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3211 * Double:: @code{.double @var{flonums}}
3212 * Eject:: @code{.eject}
3213 * Else:: @code{.else}
3214 * Elseif:: @code{.elseif}
3217 * Endef:: @code{.endef}
3220 * Endfunc:: @code{.endfunc}
3221 * Endif:: @code{.endif}
3222 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3223 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3225 * Exitm:: @code{.exitm}
3226 * Extern:: @code{.extern}
3227 * Fail:: @code{.fail}
3228 @ifclear no-file-dir
3229 * File:: @code{.file @var{string}}
3232 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3233 * Float:: @code{.float @var{flonums}}
3234 * Func:: @code{.func}
3235 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3237 * Hidden:: @code{.hidden @var{names}}
3240 * hword:: @code{.hword @var{expressions}}
3241 * Ident:: @code{.ident}
3242 * If:: @code{.if @var{absolute expression}}
3243 * Include:: @code{.include "@var{file}"}
3244 * Int:: @code{.int @var{expressions}}
3246 * Internal:: @code{.internal @var{names}}
3249 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3250 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3251 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3252 * Lflags:: @code{.lflags}
3253 @ifclear no-line-dir
3254 * Line:: @code{.line @var{line-number}}
3257 * Ln:: @code{.ln @var{line-number}}
3258 * Linkonce:: @code{.linkonce [@var{type}]}
3259 * List:: @code{.list}
3260 * Long:: @code{.long @var{expressions}}
3262 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3265 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3266 * MRI:: @code{.mri @var{val}}
3267 * Nolist:: @code{.nolist}
3268 * Octa:: @code{.octa @var{bignums}}
3269 * Org:: @code{.org @var{new-lc} , @var{fill}}
3270 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3272 * PopSection:: @code{.popsection}
3273 * Previous:: @code{.previous}
3276 * Print:: @code{.print @var{string}}
3278 * Protected:: @code{.protected @var{names}}
3281 * Psize:: @code{.psize @var{lines}, @var{columns}}
3282 * Purgem:: @code{.purgem @var{name}}
3284 * PushSection:: @code{.pushsection @var{name}}
3287 * Quad:: @code{.quad @var{bignums}}
3288 * Rept:: @code{.rept @var{count}}
3289 * Sbttl:: @code{.sbttl "@var{subheading}"}
3291 * Scl:: @code{.scl @var{class}}
3292 * Section:: @code{.section @var{name}, @var{subsection}}
3295 * Set:: @code{.set @var{symbol}, @var{expression}}
3296 * Short:: @code{.short @var{expressions}}
3297 * Single:: @code{.single @var{flonums}}
3298 * Size:: @code{.size [@var{name} , @var{expression}]}
3299 * Skip:: @code{.skip @var{size} , @var{fill}}
3300 * Sleb128:: @code{.sleb128 @var{expressions}}
3301 * Space:: @code{.space @var{size} , @var{fill}}
3303 * Stab:: @code{.stabd, .stabn, .stabs}
3306 * String:: @code{.string "@var{str}"}
3307 * Struct:: @code{.struct @var{expression}}
3309 * SubSection:: @code{.subsection}
3310 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3314 * Tag:: @code{.tag @var{structname}}
3317 * Text:: @code{.text @var{subsection}}
3318 * Title:: @code{.title "@var{heading}"}
3319 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3320 * Uleb128:: @code{.uleb128 @var{expressions}}
3322 * Val:: @code{.val @var{addr}}
3326 * Version:: @code{.version "@var{string}"}
3327 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3328 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3329 * Weak:: @code{.weak @var{names}}
3332 * Word:: @code{.word @var{expressions}}
3333 * Deprecated:: Deprecated Directives
3337 @section @code{.abort}
3339 @cindex @code{abort} directive
3340 @cindex stopping the assembly
3341 This directive stops the assembly immediately. It is for
3342 compatibility with other assemblers. The original idea was that the
3343 assembly language source would be piped into the assembler. If the sender
3344 of the source quit, it could use this directive tells @code{@value{AS}} to
3345 quit also. One day @code{.abort} will not be supported.
3349 @section @code{.ABORT}
3351 @cindex @code{ABORT} directive
3352 When producing COFF output, @code{@value{AS}} accepts this directive as a
3353 synonym for @samp{.abort}.
3356 When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
3362 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3364 @cindex padding the location counter
3365 @cindex @code{align} directive
3366 Pad the location counter (in the current subsection) to a particular storage
3367 boundary. The first expression (which must be absolute) is the alignment
3368 required, as described below.
3370 The second expression (also absolute) gives the fill value to be stored in the
3371 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3372 padding bytes are normally zero. However, on some systems, if the section is
3373 marked as containing code and the fill value is omitted, the space is filled
3374 with no-op instructions.
3376 The third expression is also absolute, and is also optional. If it is present,
3377 it is the maximum number of bytes that should be skipped by this alignment
3378 directive. If doing the alignment would require skipping more bytes than the
3379 specified maximum, then the alignment is not done at all. You can omit the
3380 fill value (the second argument) entirely by simply using two commas after the
3381 required alignment; this can be useful if you want the alignment to be filled
3382 with no-op instructions when appropriate.
3384 The way the required alignment is specified varies from system to system.
3385 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3387 the first expression is the
3388 alignment request in bytes. For example @samp{.align 8} advances
3389 the location counter until it is a multiple of 8. If the location counter
3390 is already a multiple of 8, no change is needed.
3392 For other systems, including the i386 using a.out format, and the arm and
3393 strongarm, it is the
3394 number of low-order zero bits the location counter must have after
3395 advancement. For example @samp{.align 3} advances the location
3396 counter until it a multiple of 8. If the location counter is already a
3397 multiple of 8, no change is needed.
3399 This inconsistency is due to the different behaviors of the various
3400 native assemblers for these systems which GAS must emulate.
3401 GAS also provides @code{.balign} and @code{.p2align} directives,
3402 described later, which have a consistent behavior across all
3403 architectures (but are specific to GAS).
3406 @section @code{.ascii "@var{string}"}@dots{}
3408 @cindex @code{ascii} directive
3409 @cindex string literals
3410 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3411 separated by commas. It assembles each string (with no automatic
3412 trailing zero byte) into consecutive addresses.
3415 @section @code{.asciz "@var{string}"}@dots{}
3417 @cindex @code{asciz} directive
3418 @cindex zero-terminated strings
3419 @cindex null-terminated strings
3420 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3421 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3424 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3426 @cindex padding the location counter given number of bytes
3427 @cindex @code{balign} directive
3428 Pad the location counter (in the current subsection) to a particular
3429 storage boundary. The first expression (which must be absolute) is the
3430 alignment request in bytes. For example @samp{.balign 8} advances
3431 the location counter until it is a multiple of 8. If the location counter
3432 is already a multiple of 8, no change is needed.
3434 The second expression (also absolute) gives the fill value to be stored in the
3435 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3436 padding bytes are normally zero. However, on some systems, if the section is
3437 marked as containing code and the fill value is omitted, the space is filled
3438 with no-op instructions.
3440 The third expression is also absolute, and is also optional. If it is present,
3441 it is the maximum number of bytes that should be skipped by this alignment
3442 directive. If doing the alignment would require skipping more bytes than the
3443 specified maximum, then the alignment is not done at all. You can omit the
3444 fill value (the second argument) entirely by simply using two commas after the
3445 required alignment; this can be useful if you want the alignment to be filled
3446 with no-op instructions when appropriate.
3448 @cindex @code{balignw} directive
3449 @cindex @code{balignl} directive
3450 The @code{.balignw} and @code{.balignl} directives are variants of the
3451 @code{.balign} directive. The @code{.balignw} directive treats the fill
3452 pattern as a two byte word value. The @code{.balignl} directives treats the
3453 fill pattern as a four byte longword value. For example, @code{.balignw
3454 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3455 filled in with the value 0x368d (the exact placement of the bytes depends upon
3456 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3460 @section @code{.byte @var{expressions}}
3462 @cindex @code{byte} directive
3463 @cindex integers, one byte
3464 @code{.byte} expects zero or more expressions, separated by commas.
3465 Each expression is assembled into the next byte.
3468 @section @code{.comm @var{symbol} , @var{length} }
3470 @cindex @code{comm} directive
3471 @cindex symbol, common
3472 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3473 common symbol in one object file may be merged with a defined or common symbol
3474 of the same name in another object file. If @code{@value{LD}} does not see a
3475 definition for the symbol--just one or more common symbols--then it will
3476 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3477 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3478 the same name, and they do not all have the same size, it will allocate space
3479 using the largest size.
3482 When using ELF, the @code{.comm} directive takes an optional third argument.
3483 This is the desired alignment of the symbol, specified as a byte boundary (for
3484 example, an alignment of 16 means that the least significant 4 bits of the
3485 address should be zero). The alignment must be an absolute expression, and it
3486 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3487 for the common symbol, it will use the alignment when placing the symbol. If
3488 no alignment is specified, @code{@value{AS}} will set the alignment to the
3489 largest power of two less than or equal to the size of the symbol, up to a
3494 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3495 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3499 @section @code{.data @var{subsection}}
3501 @cindex @code{data} directive
3502 @code{.data} tells @code{@value{AS}} to assemble the following statements onto the
3503 end of the data subsection numbered @var{subsection} (which is an
3504 absolute expression). If @var{subsection} is omitted, it defaults
3509 @section @code{.def @var{name}}
3511 @cindex @code{def} directive
3512 @cindex COFF symbols, debugging
3513 @cindex debugging COFF symbols
3514 Begin defining debugging information for a symbol @var{name}; the
3515 definition extends until the @code{.endef} directive is encountered.
3518 This directive is only observed when @code{@value{AS}} is configured for COFF
3519 format output; when producing @code{b.out}, @samp{.def} is recognized,
3526 @section @code{.desc @var{symbol}, @var{abs-expression}}
3528 @cindex @code{desc} directive
3529 @cindex COFF symbol descriptor
3530 @cindex symbol descriptor, COFF
3531 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3532 to the low 16 bits of an absolute expression.
3535 The @samp{.desc} directive is not available when @code{@value{AS}} is
3536 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3537 object format. For the sake of compatibility, @code{@value{AS}} accepts
3538 it, but produces no output, when configured for COFF.
3544 @section @code{.dim}
3546 @cindex @code{dim} directive
3547 @cindex COFF auxiliary symbol information
3548 @cindex auxiliary symbol information, COFF
3549 This directive is generated by compilers to include auxiliary debugging
3550 information in the symbol table. It is only permitted inside
3551 @code{.def}/@code{.endef} pairs.
3554 @samp{.dim} is only meaningful when generating COFF format output; when
3555 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
3561 @section @code{.double @var{flonums}}
3563 @cindex @code{double} directive
3564 @cindex floating point numbers (double)
3565 @code{.double} expects zero or more flonums, separated by commas. It
3566 assembles floating point numbers.
3568 The exact kind of floating point numbers emitted depends on how
3569 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
3573 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3574 in @sc{ieee} format.
3579 @section @code{.eject}
3581 @cindex @code{eject} directive
3582 @cindex new page, in listings
3583 @cindex page, in listings
3584 @cindex listing control: new page
3585 Force a page break at this point, when generating assembly listings.
3588 @section @code{.else}
3590 @cindex @code{else} directive
3591 @code{.else} is part of the @code{@value{AS}} support for conditional
3592 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3593 of code to be assembled if the condition for the preceding @code{.if}
3597 @section @code{.elseif}
3599 @cindex @code{elseif} directive
3600 @code{.elseif} is part of the @code{@value{AS}} support for conditional
3601 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3602 @code{.if} block that would otherwise fill the entire @code{.else} section.
3605 @section @code{.end}
3607 @cindex @code{end} directive
3608 @code{.end} marks the end of the assembly file. @code{@value{AS}} does not
3609 process anything in the file past the @code{.end} directive.
3613 @section @code{.endef}
3615 @cindex @code{endef} directive
3616 This directive flags the end of a symbol definition begun with
3620 @samp{.endef} is only meaningful when generating COFF format output; if
3621 @code{@value{AS}} is configured to generate @code{b.out}, it accepts this
3622 directive but ignores it.
3627 @section @code{.endfunc}
3628 @cindex @code{endfunc} directive
3629 @code{.endfunc} marks the end of a function specified with @code{.func}.
3632 @section @code{.endif}
3634 @cindex @code{endif} directive
3635 @code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
3636 it marks the end of a block of code that is only assembled
3637 conditionally. @xref{If,,@code{.if}}.
3640 @section @code{.equ @var{symbol}, @var{expression}}
3642 @cindex @code{equ} directive
3643 @cindex assigning values to symbols
3644 @cindex symbols, assigning values to
3645 This directive sets the value of @var{symbol} to @var{expression}.
3646 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3649 The syntax for @code{equ} on the HPPA is
3650 @samp{@var{symbol} .equ @var{expression}}.
3654 @section @code{.equiv @var{symbol}, @var{expression}}
3655 @cindex @code{equiv} directive
3656 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3657 the assembler will signal an error if @var{symbol} is already defined.
3659 Except for the contents of the error message, this is roughly equivalent to
3668 @section @code{.err}
3669 @cindex @code{err} directive
3670 If @code{@value{AS}} assembles a @code{.err} directive, it will print an error
3671 message and, unless the @code{-Z} option was used, it will not generate an
3672 object file. This can be used to signal error an conditionally compiled code.
3675 @section @code{.exitm}
3676 Exit early from the current macro definition. @xref{Macro}.
3679 @section @code{.extern}
3681 @cindex @code{extern} directive
3682 @code{.extern} is accepted in the source program---for compatibility
3683 with other assemblers---but it is ignored. @code{@value{AS}} treats
3684 all undefined symbols as external.
3687 @section @code{.fail @var{expression}}
3689 @cindex @code{fail} directive
3690 Generates an error or a warning. If the value of the @var{expression} is 500
3691 or more, @code{@value{AS}} will print a warning message. If the value is less
3692 than 500, @code{@value{AS}} will print an error message. The message will
3693 include the value of @var{expression}. This can occasionally be useful inside
3694 complex nested macros or conditional assembly.
3696 @ifclear no-file-dir
3698 @section @code{.file @var{string}}
3700 @cindex @code{file} directive
3701 @cindex logical file name
3702 @cindex file name, logical
3703 @code{.file} tells @code{@value{AS}} that we are about to start a new logical
3704 file. @var{string} is the new file name. In general, the filename is
3705 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
3706 to specify an empty file name, you must give the quotes--@code{""}. This
3707 statement may go away in future: it is only recognized to be compatible with
3708 old @code{@value{AS}} programs.
3710 In some configurations of @code{@value{AS}}, @code{.file} has already been
3711 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
3716 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
3718 @cindex @code{fill} directive
3719 @cindex writing patterns in memory
3720 @cindex patterns, writing in memory
3721 @var{result}, @var{size} and @var{value} are absolute expressions.
3722 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
3723 may be zero or more. @var{Size} may be zero or more, but if it is
3724 more than 8, then it is deemed to have the value 8, compatible with
3725 other people's assemblers. The contents of each @var{repeat} bytes
3726 is taken from an 8-byte number. The highest order 4 bytes are
3727 zero. The lowest order 4 bytes are @var{value} rendered in the
3728 byte-order of an integer on the computer @code{@value{AS}} is assembling for.
3729 Each @var{size} bytes in a repetition is taken from the lowest order
3730 @var{size} bytes of this number. Again, this bizarre behavior is
3731 compatible with other people's assemblers.
3733 @var{size} and @var{value} are optional.
3734 If the second comma and @var{value} are absent, @var{value} is
3735 assumed zero. If the first comma and following tokens are absent,
3736 @var{size} is assumed to be 1.
3739 @section @code{.float @var{flonums}}
3741 @cindex floating point numbers (single)
3742 @cindex @code{float} directive
3743 This directive assembles zero or more flonums, separated by commas. It
3744 has the same effect as @code{.single}.
3746 The exact kind of floating point numbers emitted depends on how
3747 @code{@value{AS}} is configured.
3748 @xref{Machine Dependencies}.
3752 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
3753 in @sc{ieee} format.
3758 @section @code{.func @var{name}[,@var{label}]}
3759 @cindex @code{func} directive
3760 @code{.func} emits debugging information to denote function @var{name}, and
3761 is ignored unless the file is assembled with debugging enabled.
3762 Only @samp{--gstabs} is currently supported.
3763 @var{label} is the entry point of the function and if omitted @var{name}
3764 prepended with the @samp{leading char} is used.
3765 @samp{leading char} is usually @code{_} or nothing, depending on the target.
3766 All functions are currently defined to have @code{void} return type.
3767 The function must be terminated with @code{.endfunc}.
3770 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3772 @cindex @code{global} directive
3773 @cindex symbol, making visible to linker
3774 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
3775 @var{symbol} in your partial program, its value is made available to
3776 other partial programs that are linked with it. Otherwise,
3777 @var{symbol} takes its attributes from a symbol of the same name
3778 from another file linked into the same program.
3780 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
3781 compatibility with other assemblers.
3784 On the HPPA, @code{.global} is not always enough to make it accessible to other
3785 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
3786 @xref{HPPA Directives,, HPPA Assembler Directives}.
3791 @section @code{.hidden @var{names}}
3793 @cindex @code{.hidden} directive
3795 This one of the ELF visibility directives. The other two are
3796 @pxref{Internal,,@code{.internal}} and @pxref{Protected,,@code{.protected}}
3798 This directive overrides the named symbols default visibility (which is set by
3799 their binding: local, global or weak). The directive sets the visibility to
3800 @code{hidden} which means that the symbols are not visible to other components.
3801 Such symbols are always considered to be @code{protected} as well.
3805 @section @code{.hword @var{expressions}}
3807 @cindex @code{hword} directive
3808 @cindex integers, 16-bit
3809 @cindex numbers, 16-bit
3810 @cindex sixteen bit integers
3811 This expects zero or more @var{expressions}, and emits
3812 a 16 bit number for each.
3815 This directive is a synonym for @samp{.short}; depending on the target
3816 architecture, it may also be a synonym for @samp{.word}.
3820 This directive is a synonym for @samp{.short}.
3823 This directive is a synonym for both @samp{.short} and @samp{.word}.
3828 @section @code{.ident}
3830 @cindex @code{ident} directive
3831 This directive is used by some assemblers to place tags in object files.
3832 @code{@value{AS}} simply accepts the directive for source-file
3833 compatibility with such assemblers, but does not actually emit anything
3837 @section @code{.if @var{absolute expression}}
3839 @cindex conditional assembly
3840 @cindex @code{if} directive
3841 @code{.if} marks the beginning of a section of code which is only
3842 considered part of the source program being assembled if the argument
3843 (which must be an @var{absolute expression}) is non-zero. The end of
3844 the conditional section of code must be marked by @code{.endif}
3845 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
3846 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
3847 If you have several conditions to check, @code{.elseif} may be used to avoid
3848 nesting blocks if/else within each subsequent @code{.else} block.
3850 The following variants of @code{.if} are also supported:
3852 @cindex @code{ifdef} directive
3853 @item .ifdef @var{symbol}
3854 Assembles the following section of code if the specified @var{symbol}
3857 @cindex @code{ifc} directive
3858 @item .ifc @var{string1},@var{string2}
3859 Assembles the following section of code if the two strings are the same. The
3860 strings may be optionally quoted with single quotes. If they are not quoted,
3861 the first string stops at the first comma, and the second string stops at the
3862 end of the line. Strings which contain whitespace should be quoted. The
3863 string comparison is case sensitive.
3865 @cindex @code{ifeq} directive
3866 @item .ifeq @var{absolute expression}
3867 Assembles the following section of code if the argument is zero.
3869 @cindex @code{ifeqs} directive
3870 @item .ifeqs @var{string1},@var{string2}
3871 Another form of @code{.ifc}. The strings must be quoted using double quotes.
3873 @cindex @code{ifge} directive
3874 @item .ifge @var{absolute expression}
3875 Assembles the following section of code if the argument is greater than or
3878 @cindex @code{ifgt} directive
3879 @item .ifgt @var{absolute expression}
3880 Assembles the following section of code if the argument is greater than zero.
3882 @cindex @code{ifle} directive
3883 @item .ifle @var{absolute expression}
3884 Assembles the following section of code if the argument is less than or equal
3887 @cindex @code{iflt} directive
3888 @item .iflt @var{absolute expression}
3889 Assembles the following section of code if the argument is less than zero.
3891 @cindex @code{ifnc} directive
3892 @item .ifnc @var{string1},@var{string2}.
3893 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
3894 following section of code if the two strings are not the same.
3896 @cindex @code{ifndef} directive
3897 @cindex @code{ifnotdef} directive
3898 @item .ifndef @var{symbol}
3899 @itemx .ifnotdef @var{symbol}
3900 Assembles the following section of code if the specified @var{symbol}
3901 has not been defined. Both spelling variants are equivalent.
3903 @cindex @code{ifne} directive
3904 @item .ifne @var{absolute expression}
3905 Assembles the following section of code if the argument is not equal to zero
3906 (in other words, this is equivalent to @code{.if}).
3908 @cindex @code{ifnes} directive
3909 @item .ifnes @var{string1},@var{string2}
3910 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
3911 following section of code if the two strings are not the same.
3915 @section @code{.include "@var{file}"}
3917 @cindex @code{include} directive
3918 @cindex supporting files, including
3919 @cindex files, including
3920 This directive provides a way to include supporting files at specified
3921 points in your source program. The code from @var{file} is assembled as
3922 if it followed the point of the @code{.include}; when the end of the
3923 included file is reached, assembly of the original file continues. You
3924 can control the search paths used with the @samp{-I} command-line option
3925 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
3929 @section @code{.int @var{expressions}}
3931 @cindex @code{int} directive
3932 @cindex integers, 32-bit
3933 Expect zero or more @var{expressions}, of any section, separated by commas.
3934 For each expression, emit a number that, at run time, is the value of that
3935 expression. The byte order and bit size of the number depends on what kind
3936 of target the assembly is for.
3940 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
3941 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
3948 @section @code{.internal @var{names}}
3950 @cindex @code{.internal} directive
3952 This one of the ELF visibility directives. The other two are
3953 @pxref{Hidden,,@code{.hidden}} and @pxref{Protected,,@code{.protected}}
3955 This directive overrides the named symbols default visibility (which is set by
3956 their binding: local, global or weak). The directive sets the visibility to
3957 @code{internal} which means that the symbols are considered to be @code{hidden}
3958 (ie not visible to other components), and that some extra, processor specific
3959 processing must also be performed upon the symbols as well.
3963 @section @code{.irp @var{symbol},@var{values}}@dots{}
3965 @cindex @code{irp} directive
3966 Evaluate a sequence of statements assigning different values to @var{symbol}.
3967 The sequence of statements starts at the @code{.irp} directive, and is
3968 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
3969 set to @var{value}, and the sequence of statements is assembled. If no
3970 @var{value} is listed, the sequence of statements is assembled once, with
3971 @var{symbol} set to the null string. To refer to @var{symbol} within the
3972 sequence of statements, use @var{\symbol}.
3974 For example, assembling
3982 is equivalent to assembling
3991 @section @code{.irpc @var{symbol},@var{values}}@dots{}
3993 @cindex @code{irpc} directive
3994 Evaluate a sequence of statements assigning different values to @var{symbol}.
3995 The sequence of statements starts at the @code{.irpc} directive, and is
3996 terminated by an @code{.endr} directive. For each character in @var{value},
3997 @var{symbol} is set to the character, and the sequence of statements is
3998 assembled. If no @var{value} is listed, the sequence of statements is
3999 assembled once, with @var{symbol} set to the null string. To refer to
4000 @var{symbol} within the sequence of statements, use @var{\symbol}.
4002 For example, assembling
4010 is equivalent to assembling
4019 @section @code{.lcomm @var{symbol} , @var{length}}
4021 @cindex @code{lcomm} directive
4022 @cindex local common symbols
4023 @cindex symbols, local common
4024 Reserve @var{length} (an absolute expression) bytes for a local common
4025 denoted by @var{symbol}. The section and value of @var{symbol} are
4026 those of the new local common. The addresses are allocated in the bss
4027 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4028 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4029 not visible to @code{@value{LD}}.
4032 Some targets permit a third argument to be used with @code{.lcomm}. This
4033 argument specifies the desired alignment of the symbol in the bss section.
4037 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4038 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4042 @section @code{.lflags}
4044 @cindex @code{lflags} directive (ignored)
4045 @code{@value{AS}} accepts this directive, for compatibility with other
4046 assemblers, but ignores it.
4048 @ifclear no-line-dir
4050 @section @code{.line @var{line-number}}
4052 @cindex @code{line} directive
4056 @section @code{.ln @var{line-number}}
4058 @cindex @code{ln} directive
4060 @cindex logical line number
4062 Change the logical line number. @var{line-number} must be an absolute
4063 expression. The next line has that logical line number. Therefore any other
4064 statements on the current line (after a statement separator character) are
4065 reported as on logical line number @var{line-number} @minus{} 1. One day
4066 @code{@value{AS}} will no longer support this directive: it is recognized only
4067 for compatibility with existing assembler programs.
4071 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4072 not available; use the synonym @code{.ln} in that context.
4077 @ifclear no-line-dir
4078 Even though this is a directive associated with the @code{a.out} or
4079 @code{b.out} object-code formats, @code{@value{AS}} still recognizes it
4080 when producing COFF output, and treats @samp{.line} as though it
4081 were the COFF @samp{.ln} @emph{if} it is found outside a
4082 @code{.def}/@code{.endef} pair.
4084 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4085 used by compilers to generate auxiliary symbol information for
4090 @section @code{.linkonce [@var{type}]}
4092 @cindex @code{linkonce} directive
4093 @cindex common sections
4094 Mark the current section so that the linker only includes a single copy of it.
4095 This may be used to include the same section in several different object files,
4096 but ensure that the linker will only include it once in the final output file.
4097 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4098 Duplicate sections are detected based on the section name, so it should be
4101 This directive is only supported by a few object file formats; as of this
4102 writing, the only object file format which supports it is the Portable
4103 Executable format used on Windows NT.
4105 The @var{type} argument is optional. If specified, it must be one of the
4106 following strings. For example:
4110 Not all types may be supported on all object file formats.
4114 Silently discard duplicate sections. This is the default.
4117 Warn if there are duplicate sections, but still keep only one copy.
4120 Warn if any of the duplicates have different sizes.
4123 Warn if any of the duplicates do not have exactly the same contents.
4127 @section @code{.ln @var{line-number}}
4129 @cindex @code{ln} directive
4130 @ifclear no-line-dir
4131 @samp{.ln} is a synonym for @samp{.line}.
4134 Tell @code{@value{AS}} to change the logical line number. @var{line-number}
4135 must be an absolute expression. The next line has that logical
4136 line number, so any other statements on the current line (after a
4137 statement separator character @code{;}) are reported as on logical
4138 line number @var{line-number} @minus{} 1.
4141 This directive is accepted, but ignored, when @code{@value{AS}} is
4142 configured for @code{b.out}; its effect is only associated with COFF
4148 @section @code{.mri @var{val}}
4150 @cindex @code{mri} directive
4151 @cindex MRI mode, temporarily
4152 If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If
4153 @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change
4154 affects code assembled until the next @code{.mri} directive, or until the end
4155 of the file. @xref{M, MRI mode, MRI mode}.
4158 @section @code{.list}
4160 @cindex @code{list} directive
4161 @cindex listing control, turning on
4162 Control (in conjunction with the @code{.nolist} directive) whether or
4163 not assembly listings are generated. These two directives maintain an
4164 internal counter (which is zero initially). @code{.list} increments the
4165 counter, and @code{.nolist} decrements it. Assembly listings are
4166 generated whenever the counter is greater than zero.
4168 By default, listings are disabled. When you enable them (with the
4169 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4170 the initial value of the listing counter is one.
4173 @section @code{.long @var{expressions}}
4175 @cindex @code{long} directive
4176 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4179 @c no one seems to know what this is for or whether this description is
4180 @c what it really ought to do
4182 @section @code{.lsym @var{symbol}, @var{expression}}
4184 @cindex @code{lsym} directive
4185 @cindex symbol, not referenced in assembly
4186 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4187 the hash table, ensuring it cannot be referenced by name during the
4188 rest of the assembly. This sets the attributes of the symbol to be
4189 the same as the expression value:
4191 @var{other} = @var{descriptor} = 0
4192 @var{type} = @r{(section of @var{expression})}
4193 @var{value} = @var{expression}
4196 The new symbol is not flagged as external.
4200 @section @code{.macro}
4203 The commands @code{.macro} and @code{.endm} allow you to define macros that
4204 generate assembly output. For example, this definition specifies a macro
4205 @code{sum} that puts a sequence of numbers into memory:
4208 .macro sum from=0, to=5
4217 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4229 @item .macro @var{macname}
4230 @itemx .macro @var{macname} @var{macargs} @dots{}
4231 @cindex @code{macro} directive
4232 Begin the definition of a macro called @var{macname}. If your macro
4233 definition requires arguments, specify their names after the macro name,
4234 separated by commas or spaces. You can supply a default value for any
4235 macro argument by following the name with @samp{=@var{deflt}}. For
4236 example, these are all valid @code{.macro} statements:
4240 Begin the definition of a macro called @code{comm}, which takes no
4243 @item .macro plus1 p, p1
4244 @itemx .macro plus1 p p1
4245 Either statement begins the definition of a macro called @code{plus1},
4246 which takes two arguments; within the macro definition, write
4247 @samp{\p} or @samp{\p1} to evaluate the arguments.
4249 @item .macro reserve_str p1=0 p2
4250 Begin the definition of a macro called @code{reserve_str}, with two
4251 arguments. The first argument has a default value, but not the second.
4252 After the definition is complete, you can call the macro either as
4253 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4254 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4255 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4256 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4259 When you call a macro, you can specify the argument values either by
4260 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4261 @samp{sum to=17, from=9}.
4264 @cindex @code{endm} directive
4265 Mark the end of a macro definition.
4268 @cindex @code{exitm} directive
4269 Exit early from the current macro definition.
4271 @cindex number of macros executed
4272 @cindex macros, count executed
4274 @code{@value{AS}} maintains a counter of how many macros it has
4275 executed in this pseudo-variable; you can copy that number to your
4276 output with @samp{\@@}, but @emph{only within a macro definition}.
4279 @item LOCAL @var{name} [ , @dots{} ]
4280 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4281 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4282 Alternate macro syntax}.
4284 Generate a string replacement for each of the @var{name} arguments, and
4285 replace any instances of @var{name} in each macro expansion. The
4286 replacement string is unique in the assembly, and different for each
4287 separate macro expansion. @code{LOCAL} allows you to write macros that
4288 define symbols, without fear of conflict between separate macro expansions.
4293 @section @code{.nolist}
4295 @cindex @code{nolist} directive
4296 @cindex listing control, turning off
4297 Control (in conjunction with the @code{.list} directive) whether or
4298 not assembly listings are generated. These two directives maintain an
4299 internal counter (which is zero initially). @code{.list} increments the
4300 counter, and @code{.nolist} decrements it. Assembly listings are
4301 generated whenever the counter is greater than zero.
4304 @section @code{.octa @var{bignums}}
4306 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4307 @cindex @code{octa} directive
4308 @cindex integer, 16-byte
4309 @cindex sixteen byte integer
4310 This directive expects zero or more bignums, separated by commas. For each
4311 bignum, it emits a 16-byte integer.
4313 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4314 hence @emph{octa}-word for 16 bytes.
4317 @section @code{.org @var{new-lc} , @var{fill}}
4319 @cindex @code{org} directive
4320 @cindex location counter, advancing
4321 @cindex advancing location counter
4322 @cindex current address, advancing
4323 Advance the location counter of the current section to
4324 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4325 expression with the same section as the current subsection. That is,
4326 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4327 wrong section, the @code{.org} directive is ignored. To be compatible
4328 with former assemblers, if the section of @var{new-lc} is absolute,
4329 @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4330 is the same as the current subsection.
4332 @code{.org} may only increase the location counter, or leave it
4333 unchanged; you cannot use @code{.org} to move the location counter
4336 @c double negative used below "not undefined" because this is a specific
4337 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4338 @c section. doc@cygnus.com 18feb91
4339 Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4340 may not be undefined. If you really detest this restriction we eagerly await
4341 a chance to share your improved assembler.
4343 Beware that the origin is relative to the start of the section, not
4344 to the start of the subsection. This is compatible with other
4345 people's assemblers.
4347 When the location counter (of the current subsection) is advanced, the
4348 intervening bytes are filled with @var{fill} which should be an
4349 absolute expression. If the comma and @var{fill} are omitted,
4350 @var{fill} defaults to zero.
4353 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4355 @cindex padding the location counter given a power of two
4356 @cindex @code{p2align} directive
4357 Pad the location counter (in the current subsection) to a particular
4358 storage boundary. The first expression (which must be absolute) is the
4359 number of low-order zero bits the location counter must have after
4360 advancement. For example @samp{.p2align 3} advances the location
4361 counter until it a multiple of 8. If the location counter is already a
4362 multiple of 8, no change is needed.
4364 The second expression (also absolute) gives the fill value to be stored in the
4365 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4366 padding bytes are normally zero. However, on some systems, if the section is
4367 marked as containing code and the fill value is omitted, the space is filled
4368 with no-op instructions.
4370 The third expression is also absolute, and is also optional. If it is present,
4371 it is the maximum number of bytes that should be skipped by this alignment
4372 directive. If doing the alignment would require skipping more bytes than the
4373 specified maximum, then the alignment is not done at all. You can omit the
4374 fill value (the second argument) entirely by simply using two commas after the
4375 required alignment; this can be useful if you want the alignment to be filled
4376 with no-op instructions when appropriate.
4378 @cindex @code{p2alignw} directive
4379 @cindex @code{p2alignl} directive
4380 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4381 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4382 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4383 fill pattern as a four byte longword value. For example, @code{.p2alignw
4384 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4385 filled in with the value 0x368d (the exact placement of the bytes depends upon
4386 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4391 @section @code{.previous}
4393 @cindex @code{.previous} directive
4394 @cindex Section Stack
4395 This is one of the ELF section stack manipulation directives. The others are
4396 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4399 This directive swaps the current section (and subsection) with most recently
4400 referenced section (and subsection) prior to this one. Multiple
4401 @code{.previous} directives in a row will flip between two sections (and their
4404 In terms of the section stack, this directive swaps the current section with
4405 the top section on the section stack.
4410 @section @code{.popsection}
4412 @cindex @code{.popsection} directive
4413 @cindex Section Stack
4414 This is one of the ELF section stack manipulation directives. The others are
4415 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4418 This directive replaces the current section (and subsection) with the top
4419 section (and subsection) on the section stack. This section is popped off the
4424 @section @code{.print @var{string}}
4426 @cindex @code{print} directive
4427 @code{@value{AS}} will print @var{string} on the standard output during
4428 assembly. You must put @var{string} in double quotes.
4432 @section @code{.protected @var{names}}
4434 @cindex @code{.protected} directive
4436 This one of the ELF visibility directives. The other two are
4437 @pxref{Hidden} and @pxref{Internal}
4439 This directive overrides the named symbols default visibility (which is set by
4440 their binding: local, global or weak). The directive sets the visibility to
4441 @code{protected} which means that any references to the symbols from within the
4442 components that defines them must be resolved to the definition in that
4443 component, even if a definition in another component would normally preempt
4448 @section @code{.psize @var{lines} , @var{columns}}
4450 @cindex @code{psize} directive
4451 @cindex listing control: paper size
4452 @cindex paper size, for listings
4453 Use this directive to declare the number of lines---and, optionally, the
4454 number of columns---to use for each page, when generating listings.
4456 If you do not use @code{.psize}, listings use a default line-count
4457 of 60. You may omit the comma and @var{columns} specification; the
4458 default width is 200 columns.
4460 @code{@value{AS}} generates formfeeds whenever the specified number of
4461 lines is exceeded (or whenever you explicitly request one, using
4464 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4465 those explicitly specified with @code{.eject}.
4468 @section @code{.purgem @var{name}}
4470 @cindex @code{purgem} directive
4471 Undefine the macro @var{name}, so that later uses of the string will not be
4472 expanded. @xref{Macro}.
4476 @section @code{.pushsection @var{name} , @var{subsection}}
4478 @cindex @code{.pushsection} directive
4479 @cindex Section Stack
4480 This is one of the ELF section stack manipulation directives. The others are
4481 @pxref{Section}, @xref{SubSection}, @pxref{PopSection}, and
4484 This directive is a synonym for @code{.section}. It psuhes the current section
4485 (and subsection) onto the top of the section stack, and then replaces the
4486 current section and subsection with @code{name} and @code{subsection}.
4490 @section @code{.quad @var{bignums}}
4492 @cindex @code{quad} directive
4493 @code{.quad} expects zero or more bignums, separated by commas. For
4494 each bignum, it emits
4496 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4497 warning message; and just takes the lowest order 8 bytes of the bignum.
4498 @cindex eight-byte integer
4499 @cindex integer, 8-byte
4501 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4502 hence @emph{quad}-word for 8 bytes.
4505 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4506 warning message; and just takes the lowest order 16 bytes of the bignum.
4507 @cindex sixteen-byte integer
4508 @cindex integer, 16-byte
4512 @section @code{.rept @var{count}}
4514 @cindex @code{rept} directive
4515 Repeat the sequence of lines between the @code{.rept} directive and the next
4516 @code{.endr} directive @var{count} times.
4518 For example, assembling
4526 is equivalent to assembling
4535 @section @code{.sbttl "@var{subheading}"}
4537 @cindex @code{sbttl} directive
4538 @cindex subtitles for listings
4539 @cindex listing control: subtitle
4540 Use @var{subheading} as the title (third line, immediately after the
4541 title line) when generating assembly listings.
4543 This directive affects subsequent pages, as well as the current page if
4544 it appears within ten lines of the top of a page.
4548 @section @code{.scl @var{class}}
4550 @cindex @code{scl} directive
4551 @cindex symbol storage class (COFF)
4552 @cindex COFF symbol storage class
4553 Set the storage-class value for a symbol. This directive may only be
4554 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4555 whether a symbol is static or external, or it may record further
4556 symbolic debugging information.
4559 The @samp{.scl} directive is primarily associated with COFF output; when
4560 configured to generate @code{b.out} output format, @code{@value{AS}}
4561 accepts this directive but ignores it.
4566 @section @code{.section @var{name}} (COFF version)
4568 @cindex @code{section} directive
4569 @cindex named section
4570 Use the @code{.section} directive to assemble the following code into a section
4573 This directive is only supported for targets that actually support arbitrarily
4574 named sections; on @code{a.out} targets, for example, it is not accepted, even
4575 with a standard @code{a.out} section name.
4577 For COFF targets, the @code{.section} directive is used in one of the following
4581 .section @var{name}[, "@var{flags}"]
4582 .section @var{name}[, @var{subsegment}]
4585 If the optional argument is quoted, it is taken as flags to use for the
4586 section. Each flag is a single character. The following flags are recognized:
4589 bss section (uninitialized data)
4591 section is not loaded
4601 shared section (meaningful for PE targets)
4604 If no flags are specified, the default flags depend upon the section name. If
4605 the section name is not recognized, the default will be for the section to be
4606 loaded and writable.
4608 If the optional argument to the @code{.section} directive is not quoted, it is
4609 taken as a subsegment number (@pxref{Sub-Sections}).
4612 @section @code{.section @var{name}} (ELF version)
4614 @cindex @code{section} directive
4615 @cindex named section
4617 @cindex Section Stack
4618 This is one of the ELF section stack manipulation directives. The others are
4619 @xref{SubSection}, @pxref{PushSection}@pxref{PopSection}, and
4623 For ELF targets, the @code{.section} directive is used like this:
4626 .section @var{name} [, "@var{flags}"[, @@@var{type}]]
4629 The optional @var{flags} argument is a quoted string which may contain any
4630 combintion of the following characters:
4633 section is allocatable
4637 section is executable
4640 The optional @var{type} argument may contain one of the following constants:
4643 section contains data
4645 section does not contain data (i.e., section only occupies space)
4648 If no flags are specified, the default flags depend upon the section name. If
4649 the section name is not recognized, the default will be for the section to have
4650 none of the above flags: it will not be allocated in memory, nor writable, nor
4651 executable. The section will contain data.
4653 For ELF targets, the assembler supports another type of @code{.section}
4654 directive for compatibility with the Solaris assembler:
4657 .section "@var{name}"[, @var{flags}...]
4660 Note that the section name is quoted. There may be a sequence of comma
4664 section is allocatable
4668 section is executable
4671 This directive replaces the current section and subsection. The replaced
4672 section and subsection are pushed onto the section stack. See the contents of
4673 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
4674 how this directive and the other section stack directives work.
4677 @section @code{.set @var{symbol}, @var{expression}}
4679 @cindex @code{set} directive
4680 @cindex symbol value, setting
4681 Set the value of @var{symbol} to @var{expression}. This
4682 changes @var{symbol}'s value and type to conform to
4683 @var{expression}. If @var{symbol} was flagged as external, it remains
4684 flagged (@pxref{Symbol Attributes}).
4686 You may @code{.set} a symbol many times in the same assembly.
4688 If you @code{.set} a global symbol, the value stored in the object
4689 file is the last value stored into it.
4692 The syntax for @code{set} on the HPPA is
4693 @samp{@var{symbol} .set @var{expression}}.
4697 @section @code{.short @var{expressions}}
4699 @cindex @code{short} directive
4701 @code{.short} is normally the same as @samp{.word}.
4702 @xref{Word,,@code{.word}}.
4704 In some configurations, however, @code{.short} and @code{.word} generate
4705 numbers of different lengths; @pxref{Machine Dependencies}.
4709 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
4712 This expects zero or more @var{expressions}, and emits
4713 a 16 bit number for each.
4718 @section @code{.single @var{flonums}}
4720 @cindex @code{single} directive
4721 @cindex floating point numbers (single)
4722 This directive assembles zero or more flonums, separated by commas. It
4723 has the same effect as @code{.float}.
4725 The exact kind of floating point numbers emitted depends on how
4726 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
4730 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
4731 numbers in @sc{ieee} format.
4736 @section @code{.size} (COFF version)
4738 @cindex @code{size} directive
4739 This directive is generated by compilers to include auxiliary debugging
4740 information in the symbol table. It is only permitted inside
4741 @code{.def}/@code{.endef} pairs.
4744 @samp{.size} is only meaningful when generating COFF format output; when
4745 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4749 @section @code{.size @var{name} , @var{expression}} (ELF version)
4750 @cindex @code{size} directive
4752 This directive is used to set the size associated with a symbol @var{name}.
4753 The size in bytes is computed from @var{expression} which can make use of label
4754 arithmetic. This directive is typically used to set the size of function
4758 @section @code{.sleb128 @var{expressions}}
4760 @cindex @code{sleb128} directive
4761 @var{sleb128} stands for ``signed little endian base 128.'' This is a
4762 compact, variable length representation of numbers used by the DWARF
4763 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
4765 @ifclear no-space-dir
4767 @section @code{.skip @var{size} , @var{fill}}
4769 @cindex @code{skip} directive
4770 @cindex filling memory
4771 This directive emits @var{size} bytes, each of value @var{fill}. Both
4772 @var{size} and @var{fill} are absolute expressions. If the comma and
4773 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
4777 @section @code{.space @var{size} , @var{fill}}
4779 @cindex @code{space} directive
4780 @cindex filling memory
4781 This directive emits @var{size} bytes, each of value @var{fill}. Both
4782 @var{size} and @var{fill} are absolute expressions. If the comma
4783 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
4788 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
4789 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
4790 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
4791 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
4800 @section @code{.space}
4801 @cindex @code{space} directive
4803 On the AMD 29K, this directive is ignored; it is accepted for
4804 compatibility with other AMD 29K assemblers.
4807 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
4808 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
4814 @section @code{.stabd, .stabn, .stabs}
4816 @cindex symbolic debuggers, information for
4817 @cindex @code{stab@var{x}} directives
4818 There are three directives that begin @samp{.stab}.
4819 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
4820 The symbols are not entered in the @code{@value{AS}} hash table: they
4821 cannot be referenced elsewhere in the source file.
4822 Up to five fields are required:
4826 This is the symbol's name. It may contain any character except
4827 @samp{\000}, so is more general than ordinary symbol names. Some
4828 debuggers used to code arbitrarily complex structures into symbol names
4832 An absolute expression. The symbol's type is set to the low 8 bits of
4833 this expression. Any bit pattern is permitted, but @code{@value{LD}}
4834 and debuggers choke on silly bit patterns.
4837 An absolute expression. The symbol's ``other'' attribute is set to the
4838 low 8 bits of this expression.
4841 An absolute expression. The symbol's descriptor is set to the low 16
4842 bits of this expression.
4845 An absolute expression which becomes the symbol's value.
4848 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
4849 or @code{.stabs} statement, the symbol has probably already been created;
4850 you get a half-formed symbol in your object file. This is
4851 compatible with earlier assemblers!
4854 @cindex @code{stabd} directive
4855 @item .stabd @var{type} , @var{other} , @var{desc}
4857 The ``name'' of the symbol generated is not even an empty string.
4858 It is a null pointer, for compatibility. Older assemblers used a
4859 null pointer so they didn't waste space in object files with empty
4862 The symbol's value is set to the location counter,
4863 relocatably. When your program is linked, the value of this symbol
4864 is the address of the location counter when the @code{.stabd} was
4867 @cindex @code{stabn} directive
4868 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
4869 The name of the symbol is set to the empty string @code{""}.
4871 @cindex @code{stabs} directive
4872 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
4873 All five fields are specified.
4879 @section @code{.string} "@var{str}"
4881 @cindex string, copying to object file
4882 @cindex @code{string} directive
4884 Copy the characters in @var{str} to the object file. You may specify more than
4885 one string to copy, separated by commas. Unless otherwise specified for a
4886 particular machine, the assembler marks the end of each string with a 0 byte.
4887 You can use any of the escape sequences described in @ref{Strings,,Strings}.
4890 @section @code{.struct @var{expression}}
4892 @cindex @code{struct} directive
4893 Switch to the absolute section, and set the section offset to @var{expression},
4894 which must be an absolute expression. You might use this as follows:
4903 This would define the symbol @code{field1} to have the value 0, the symbol
4904 @code{field2} to have the value 4, and the symbol @code{field3} to have the
4905 value 8. Assembly would be left in the absolute section, and you would need to
4906 use a @code{.section} directive of some sort to change to some other section
4907 before further assembly.
4911 @section @code{.subsection @var{name}}
4913 @cindex @code{.subsection} directive
4914 @cindex Section Stack
4915 This is one of the ELF section stack manipulation directives. The others are
4916 @pxref{Section}, @xref{PushSection}, @pxref{PopSection}, and
4919 This directive replaces the current subsection with @code{name}. The current
4920 section is not changed. The replaced subsection is put onto the section stack
4921 in place of the then current top of stack subsection.
4926 @section @code{.symver}
4927 @cindex @code{symver} directive
4928 @cindex symbol versioning
4929 @cindex versions of symbols
4930 Use the @code{.symver} directive to bind symbols to specific version nodes
4931 within a source file. This is only supported on ELF platforms, and is
4932 typically used when assembling files to be linked into a shared library.
4933 There are cases where it may make sense to use this in objects to be bound
4934 into an application itself so as to override a versioned symbol from a
4937 For ELF targets, the @code{.symver} directive can be used like this:
4939 .symver @var{name}, @var{name2@@nodename}
4941 If the symbol @var{name} is defined within the file
4942 being assembled, the @code{.symver} directive effectively creates a symbol
4943 alias with the name @var{name2@@nodename}, and in fact the main reason that we
4944 just don't try and create a regular alias is that the @var{@@} character isn't
4945 permitted in symbol names. The @var{name2} part of the name is the actual name
4946 of the symbol by which it will be externally referenced. The name @var{name}
4947 itself is merely a name of convenience that is used so that it is possible to
4948 have definitions for multiple versions of a function within a single source
4949 file, and so that the compiler can unambiguously know which version of a
4950 function is being mentioned. The @var{nodename} portion of the alias should be
4951 the name of a node specified in the version script supplied to the linker when
4952 building a shared library. If you are attempting to override a versioned
4953 symbol from a shared library, then @var{nodename} should correspond to the
4954 nodename of the symbol you are trying to override.
4956 If the symbol @var{name} is not defined within the file being assembled, all
4957 references to @var{name} will be changed to @var{name2@@nodename}. If no
4958 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
4961 Another usage of the @code{.symver} directive is:
4963 .symver @var{name}, @var{name2@@@@nodename}
4965 In this case, the symbol @var{name} must exist and be defined within
4966 the file being assembled. It is similiar to @var{name2@@nodename}. The
4967 difference is @var{name2@@@@nodename} will also be used to resolve
4968 references to @var{name2} by the linker.
4970 The third usage of the @code{.symver} directive is:
4972 .symver @var{name}, @var{name2@@@@@@nodename}
4974 When @var{name} is not defined within the
4975 file being assembled, it is treated as @var{name2@@nodename}. When
4976 @var{name} is defined within the file being assembled, the symbol
4977 name, @var{name}, will be changed to @var{name2@@@@nodename}.
4982 @section @code{.tag @var{structname}}
4984 @cindex COFF structure debugging
4985 @cindex structure debugging, COFF
4986 @cindex @code{tag} directive
4987 This directive is generated by compilers to include auxiliary debugging
4988 information in the symbol table. It is only permitted inside
4989 @code{.def}/@code{.endef} pairs. Tags are used to link structure
4990 definitions in the symbol table with instances of those structures.
4993 @samp{.tag} is only used when generating COFF format output; when
4994 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
5000 @section @code{.text @var{subsection}}
5002 @cindex @code{text} directive
5003 Tells @code{@value{AS}} to assemble the following statements onto the end of
5004 the text subsection numbered @var{subsection}, which is an absolute
5005 expression. If @var{subsection} is omitted, subsection number zero
5009 @section @code{.title "@var{heading}"}
5011 @cindex @code{title} directive
5012 @cindex listing control: title line
5013 Use @var{heading} as the title (second line, immediately after the
5014 source file name and pagenumber) when generating assembly listings.
5016 This directive affects subsequent pages, as well as the current page if
5017 it appears within ten lines of the top of a page.
5020 @section @code{.type @var{int}} (COFF version)
5022 @cindex COFF symbol type
5023 @cindex symbol type, COFF
5024 @cindex @code{type} directive
5025 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5026 records the integer @var{int} as the type attribute of a symbol table entry.
5029 @samp{.type} is associated only with COFF format output; when
5030 @code{@value{AS}} is configured for @code{b.out} output, it accepts this
5031 directive but ignores it.
5034 @section @code{.type @var{name} , @var{type description}} (ELF version)
5036 @cindex ELF symbol type
5037 @cindex symbol type, ELF
5038 @cindex @code{type} directive
5039 This directive is used to set the type of symbol @var{name} to be either a
5040 function symbol or an ojbect symbol. There are five different syntaxes
5041 supported for the @var{type description} field, in order to provide
5042 comptability with various other assemblers. The syntaxes supported are:
5045 .type <name>,#function
5046 .type <name>,#object
5048 .type <name>,@@function
5049 .type <name>,@@object
5051 .type <name>,%function
5052 .type <name>,%object
5054 .type <name>,"function"
5055 .type <name>,"object"
5057 .type <name> STT_FUNCTION
5058 .type <name> STT_OBJECT
5062 @section @code{.uleb128 @var{expressions}}
5064 @cindex @code{uleb128} directive
5065 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5066 compact, variable length representation of numbers used by the DWARF
5067 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5071 @section @code{.val @var{addr}}
5073 @cindex @code{val} directive
5074 @cindex COFF value attribute
5075 @cindex value attribute, COFF
5076 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5077 records the address @var{addr} as the value attribute of a symbol table
5081 @samp{.val} is used only for COFF output; when @code{@value{AS}} is
5082 configured for @code{b.out}, it accepts this directive but ignores it.
5088 @section @code{.version "@var{string}"}
5090 @cindex @code{.version}
5091 This directive creates a @code{.note} section and places into it an ELF
5092 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5097 @section @code{.vtable_entry @var{table}, @var{offset}}
5099 @cindex @code{.vtable_entry}
5100 This directive finds or creates a symbol @code{table} and creates a
5101 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5104 @section @code{.vtable_inherit @var{child}, @var{parent}}
5106 @cindex @code{.vtable_inherit}
5107 This directive finds the symbol @code{child} and finds or creates the symbol
5108 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5109 parent whoes addend is the value of the child symbol. As a special case the
5110 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5115 @section @code{.weak @var{names}}
5117 @cindex @code{.weak}
5118 This directive sets the weak attribute on the comma seperated list of symbol
5119 @code{names}. If the symbols do not already exist, they will be created.
5123 @section @code{.word @var{expressions}}
5125 @cindex @code{word} directive
5126 This directive expects zero or more @var{expressions}, of any section,
5127 separated by commas.
5130 For each expression, @code{@value{AS}} emits a 32-bit number.
5133 For each expression, @code{@value{AS}} emits a 16-bit number.
5138 The size of the number emitted, and its byte order,
5139 depend on what target computer the assembly is for.
5142 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5143 @c happen---32-bit addressability, period; no long/short jumps.
5144 @ifset DIFF-TBL-KLUGE
5145 @cindex difference tables altered
5146 @cindex altered difference tables
5148 @emph{Warning: Special Treatment to support Compilers}
5152 Machines with a 32-bit address space, but that do less than 32-bit
5153 addressing, require the following special treatment. If the machine of
5154 interest to you does 32-bit addressing (or doesn't require it;
5155 @pxref{Machine Dependencies}), you can ignore this issue.
5158 In order to assemble compiler output into something that works,
5159 @code{@value{AS}} occasionlly does strange things to @samp{.word} directives.
5160 Directives of the form @samp{.word sym1-sym2} are often emitted by
5161 compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
5162 directive of the form @samp{.word sym1-sym2}, and the difference between
5163 @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}}
5164 creates a @dfn{secondary jump table}, immediately before the next label.
5165 This secondary jump table is preceded by a short-jump to the
5166 first byte after the secondary table. This short-jump prevents the flow
5167 of control from accidentally falling into the new table. Inside the
5168 table is a long-jump to @code{sym2}. The original @samp{.word}
5169 contains @code{sym1} minus the address of the long-jump to
5172 If there were several occurrences of @samp{.word sym1-sym2} before the
5173 secondary jump table, all of them are adjusted. If there was a
5174 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5175 long-jump to @code{sym4} is included in the secondary jump table,
5176 and the @code{.word} directives are adjusted to contain @code{sym3}
5177 minus the address of the long-jump to @code{sym4}; and so on, for as many
5178 entries in the original jump table as necessary.
5181 @emph{This feature may be disabled by compiling @code{@value{AS}} with the
5182 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5183 assembly language programmers.
5186 @c end DIFF-TBL-KLUGE
5189 @section Deprecated Directives
5191 @cindex deprecated directives
5192 @cindex obsolescent directives
5193 One day these directives won't work.
5194 They are included for compatibility with older assemblers.
5201 @node Machine Dependencies
5202 @chapter Machine Dependent Features
5204 @cindex machine dependencies
5205 The machine instruction sets are (almost by definition) different on
5206 each machine where @code{@value{AS}} runs. Floating point representations
5207 vary as well, and @code{@value{AS}} often supports a few additional
5208 directives or command-line options for compatibility with other
5209 assemblers on a particular platform. Finally, some versions of
5210 @code{@value{AS}} support special pseudo-instructions for branch
5213 This chapter discusses most of these differences, though it does not
5214 include details on any machine's instruction set. For details on that
5215 subject, see the hardware manufacturer's manual.
5219 * AMD29K-Dependent:: AMD 29K Dependent Features
5222 * ARC-Dependent:: ARC Dependent Features
5225 * ARM-Dependent:: ARM Dependent Features
5228 * D10V-Dependent:: D10V Dependent Features
5231 * D30V-Dependent:: D30V Dependent Features
5234 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5237 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5240 * HPPA-Dependent:: HPPA Dependent Features
5243 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5246 * i386-Dependent:: Intel 80386 Dependent Features
5249 * i860-Dependent:: Intel 80860 Dependent Features
5252 * i960-Dependent:: Intel 80960 Dependent Features
5255 * M32R-Dependent:: M32R Dependent Features
5258 * M68K-Dependent:: M680x0 Dependent Features
5261 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5264 * MIPS-Dependent:: MIPS Dependent Features
5267 * SH-Dependent:: Hitachi SH Dependent Features
5270 * PJ-Dependent:: picoJava Dependent Features
5273 * Sparc-Dependent:: SPARC Dependent Features
5276 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5279 * V850-Dependent:: V850 Dependent Features
5282 * Z8000-Dependent:: Z8000 Dependent Features
5285 * Vax-Dependent:: VAX Dependent Features
5292 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5293 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5294 @c peculiarity: to preserve cross-references, there must be a node called
5295 @c "Machine Dependencies". Hence the conditional nodenames in each
5296 @c major node below. Node defaulting in makeinfo requires adjacency of
5297 @c node and sectioning commands; hence the repetition of @chapter BLAH
5298 @c in both conditional blocks.
5304 @chapter ARC Dependent Features
5307 @node Machine Dependencies
5308 @chapter ARC Dependent Features
5313 * ARC-Opts:: Options
5314 * ARC-Float:: Floating Point
5315 * ARC-Directives:: Sparc Machine Directives
5321 @cindex options for ARC
5323 @cindex architectures, ARC
5324 @cindex ARC architectures
5325 The ARC chip family includes several successive levels (or other
5326 variants) of chip, using the same core instruction set, but including
5327 a few additional instructions at each level.
5329 By default, @code{@value{AS}} assumes the core instruction set (ARC
5330 base). The @code{.cpu} pseudo-op is intended to be used to select
5334 @cindex @code{-mbig-endian} option (ARC)
5335 @cindex @code{-mlittle-endian} option (ARC)
5336 @cindex ARC big-endian output
5337 @cindex ARC little-endian output
5338 @cindex big-endian output, ARC
5339 @cindex little-endian output, ARC
5341 @itemx -mlittle-endian
5342 Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or
5343 little-endian output at run time (unlike most other @sc{gnu} development
5344 tools, which must be configured for one or the other). Use
5345 @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian}
5350 @section Floating Point
5352 @cindex floating point, ARC (@sc{ieee})
5353 @cindex ARC floating point (@sc{ieee})
5354 The ARC cpu family currently does not have hardware floating point
5355 support. Software floating point support is provided by @code{GCC}
5356 and uses @sc{ieee} floating-point numbers.
5358 @node ARC-Directives
5359 @section ARC Machine Directives
5361 @cindex ARC machine directives
5362 @cindex machine directives, ARC
5363 The ARC version of @code{@value{AS}} supports the following additional
5368 @cindex @code{cpu} directive, SPARC
5369 This must be followed by the desired cpu.
5370 The ARC is intended to be customizable, @code{.cpu} is used to
5371 select the desired variant [though currently there are none].
5378 @include c-a29k.texi
5387 @node Machine Dependencies
5388 @chapter Machine Dependent Features
5390 The machine instruction sets are different on each Hitachi chip family,
5391 and there are also some syntax differences among the families. This
5392 chapter describes the specific @code{@value{AS}} features for each
5396 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5397 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5398 * SH-Dependent:: Hitachi SH Dependent Features
5405 @include c-d10v.texi
5409 @include c-d30v.texi
5413 @include c-h8300.texi
5417 @include c-h8500.texi
5421 @include c-hppa.texi
5425 @include c-i370.texi
5429 @include c-i386.texi
5433 @include c-i860.texi
5437 @include c-i960.texi
5441 @include c-m32r.texi
5445 @include c-m68k.texi
5449 @include c-m68hc11.texi
5453 @include c-mips.texi
5457 @include c-ns32k.texi
5469 @include c-sparc.texi
5473 @include c-tic54x.texi
5485 @include c-v850.texi
5489 @c reverse effect of @down at top of generic Machine-Dep chapter
5493 @node Reporting Bugs
5494 @chapter Reporting Bugs
5495 @cindex bugs in assembler
5496 @cindex reporting bugs in assembler
5498 Your bug reports play an essential role in making @code{@value{AS}} reliable.
5500 Reporting a bug may help you by bringing a solution to your problem, or it may
5501 not. But in any case the principal function of a bug report is to help the
5502 entire community by making the next version of @code{@value{AS}} work better.
5503 Bug reports are your contribution to the maintenance of @code{@value{AS}}.
5505 In order for a bug report to serve its purpose, you must include the
5506 information that enables us to fix the bug.
5509 * Bug Criteria:: Have you found a bug?
5510 * Bug Reporting:: How to report bugs
5514 @section Have you found a bug?
5515 @cindex bug criteria
5517 If you are not sure whether you have found a bug, here are some guidelines:
5520 @cindex fatal signal
5521 @cindex assembler crash
5522 @cindex crash of assembler
5524 If the assembler gets a fatal signal, for any input whatever, that is a
5525 @code{@value{AS}} bug. Reliable assemblers never crash.
5527 @cindex error on valid input
5529 If @code{@value{AS}} produces an error message for valid input, that is a bug.
5531 @cindex invalid input
5533 If @code{@value{AS}} does not produce an error message for invalid input, that
5534 is a bug. However, you should note that your idea of ``invalid input'' might
5535 be our idea of ``an extension'' or ``support for traditional practice''.
5538 If you are an experienced user of assemblers, your suggestions for improvement
5539 of @code{@value{AS}} are welcome in any case.
5543 @section How to report bugs
5545 @cindex assembler bugs, reporting
5547 A number of companies and individuals offer support for @sc{gnu} products. If
5548 you obtained @code{@value{AS}} from a support organization, we recommend you
5549 contact that organization first.
5551 You can find contact information for many support companies and
5552 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5555 In any event, we also recommend that you send bug reports for @code{@value{AS}}
5556 to @samp{bug-gnu-utils@@gnu.org}.
5558 The fundamental principle of reporting bugs usefully is this:
5559 @strong{report all the facts}. If you are not sure whether to state a
5560 fact or leave it out, state it!
5562 Often people omit facts because they think they know what causes the problem
5563 and assume that some details do not matter. Thus, you might assume that the
5564 name of a symbol you use in an example does not matter. Well, probably it does
5565 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5566 happens to fetch from the location where that name is stored in memory;
5567 perhaps, if the name were different, the contents of that location would fool
5568 the assembler into doing the right thing despite the bug. Play it safe and
5569 give a specific, complete example. That is the easiest thing for you to do,
5570 and the most helpful.
5572 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5573 it is new to us. Therefore, always write your bug reports on the assumption
5574 that the bug has not been reported previously.
5576 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5577 bell?'' Those bug reports are useless, and we urge everyone to
5578 @emph{refuse to respond to them} except to chide the sender to report
5581 To enable us to fix the bug, you should include all these things:
5585 The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start
5586 it with the @samp{--version} argument.
5588 Without this, we will not know whether there is any point in looking for
5589 the bug in the current version of @code{@value{AS}}.
5592 Any patches you may have applied to the @code{@value{AS}} source.
5595 The type of machine you are using, and the operating system name and
5599 What compiler (and its version) was used to compile @code{@value{AS}}---e.g.
5603 The command arguments you gave the assembler to assemble your example and
5604 observe the bug. To guarantee you will not omit something important, list them
5605 all. A copy of the Makefile (or the output from make) is sufficient.
5607 If we were to try to guess the arguments, we would probably guess wrong
5608 and then we might not encounter the bug.
5611 A complete input file that will reproduce the bug. If the bug is observed when
5612 the assembler is invoked via a compiler, send the assembler source, not the
5613 high level language source. Most compilers will produce the assembler source
5614 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5615 the options @samp{-v --save-temps}; this will save the assembler source in a
5616 file with an extension of @file{.s}, and also show you exactly how
5617 @code{@value{AS}} is being run.
5620 A description of what behavior you observe that you believe is
5621 incorrect. For example, ``It gets a fatal signal.''
5623 Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we
5624 will certainly notice it. But if the bug is incorrect output, we might not
5625 notice unless it is glaringly wrong. You might as well not give us a chance to
5628 Even if the problem you experience is a fatal signal, you should still say so
5629 explicitly. Suppose something strange is going on, such as, your copy of
5630 @code{@value{AS}} is out of synch, or you have encountered a bug in the C
5631 library on your system. (This has happened!) Your copy might crash and ours
5632 would not. If you told us to expect a crash, then when ours fails to crash, we
5633 would know that the bug was not happening for us. If you had not told us to
5634 expect a crash, then we would not be able to draw any conclusion from our
5638 If you wish to suggest changes to the @code{@value{AS}} source, send us context
5639 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5640 option. Always send diffs from the old file to the new file. If you even
5641 discuss something in the @code{@value{AS}} source, refer to it by context, not
5644 The line numbers in our development sources will not match those in your
5645 sources. Your line numbers would convey no useful information to us.
5648 Here are some things that are not necessary:
5652 A description of the envelope of the bug.
5654 Often people who encounter a bug spend a lot of time investigating
5655 which changes to the input file will make the bug go away and which
5656 changes will not affect it.
5658 This is often time consuming and not very useful, because the way we
5659 will find the bug is by running a single example under the debugger
5660 with breakpoints, not by pure deduction from a series of examples.
5661 We recommend that you save your time for something else.
5663 Of course, if you can find a simpler example to report @emph{instead}
5664 of the original one, that is a convenience for us. Errors in the
5665 output will be easier to spot, running under the debugger will take
5666 less time, and so on.
5668 However, simplification is not vital; if you do not want to do this,
5669 report the bug anyway and send us the entire test case you used.
5672 A patch for the bug.
5674 A patch for the bug does help us if it is a good one. But do not omit
5675 the necessary information, such as the test case, on the assumption that
5676 a patch is all we need. We might see problems with your patch and decide
5677 to fix the problem another way, or we might not understand it at all.
5679 Sometimes with a program as complicated as @code{@value{AS}} it is very hard to
5680 construct an example that will make the program follow a certain path through
5681 the code. If you do not send us the example, we will not be able to construct
5682 one, so we will not be able to verify that the bug is fixed.
5684 And if we cannot understand what bug you are trying to fix, or why your
5685 patch should be an improvement, we will not install it. A test case will
5686 help us to understand.
5689 A guess about what the bug is or what it depends on.
5691 Such guesses are usually wrong. Even we cannot guess right about such
5692 things without first using the debugger to find the facts.
5695 @node Acknowledgements
5696 @chapter Acknowledgements
5698 If you have contributed to @code{@value{AS}} and your name isn't listed here,
5699 it is not meant as a slight. We just don't know about it. Send mail to the
5700 maintainer, and we'll correct the situation. Currently
5702 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
5704 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
5707 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
5708 information and the 68k series machines, most of the preprocessing pass, and
5709 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
5711 K. Richard Pixley maintained GAS for a while, adding various enhancements and
5712 many bug fixes, including merging support for several processors, breaking GAS
5713 up to handle multiple object file format back ends (including heavy rewrite,
5714 testing, an integration of the coff and b.out back ends), adding configuration
5715 including heavy testing and verification of cross assemblers and file splits
5716 and renaming, converted GAS to strictly ANSI C including full prototypes, added
5717 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
5718 port (including considerable amounts of reverse engineering), a SPARC opcode
5719 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
5720 assertions and made them work, much other reorganization, cleanup, and lint.
5722 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
5723 in format-specific I/O modules.
5725 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
5726 has done much work with it since.
5728 The Intel 80386 machine description was written by Eliot Dresselhaus.
5730 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
5732 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
5733 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
5735 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
5736 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
5737 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
5738 support a.out format.
5740 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
5741 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
5742 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
5743 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
5746 John Gilmore built the AMD 29000 support, added @code{.include} support, and
5747 simplified the configuration of which versions accept which directives. He
5748 updated the 68k machine description so that Motorola's opcodes always produced
5749 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
5750 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
5751 cross-compilation support, and one bug in relaxation that took a week and
5752 required the proverbial one-bit fix.
5754 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
5755 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
5756 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
5757 PowerPC assembler, and made a few other minor patches.
5759 Steve Chamberlain made @code{@value{AS}} able to generate listings.
5761 Hewlett-Packard contributed support for the HP9000/300.
5763 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
5764 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
5765 formats). This work was supported by both the Center for Software Science at
5766 the University of Utah and Cygnus Support.
5768 Support for ELF format files has been worked on by Mark Eichin of Cygnus
5769 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
5770 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
5771 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
5772 and some initial 64-bit support).
5774 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
5776 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
5777 support for openVMS/Alpha.
5779 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
5782 Several engineers at Cygnus Support have also provided many small bug fixes and
5783 configuration enhancements.
5785 Many others have contributed large or small bugfixes and enhancements. If
5786 you have contributed significant work and are not mentioned on this list, and
5787 want to be, let us know. Some of the history has been lost; we are not
5788 intentionally leaving anyone out.
5790 @node GNU Free Documentation License
5791 @chapter GNU Free Documentation License
5793 GNU Free Documentation License
5795 Version 1.1, March 2000
5797 Copyright (C) 2000 Free Software Foundation, Inc.
5798 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
5800 Everyone is permitted to copy and distribute verbatim copies
5801 of this license document, but changing it is not allowed.
5806 The purpose of this License is to make a manual, textbook, or other
5807 written document "free" in the sense of freedom: to assure everyone
5808 the effective freedom to copy and redistribute it, with or without
5809 modifying it, either commercially or noncommercially. Secondarily,
5810 this License preserves for the author and publisher a way to get
5811 credit for their work, while not being considered responsible for
5812 modifications made by others.
5814 This License is a kind of "copyleft", which means that derivative
5815 works of the document must themselves be free in the same sense. It
5816 complements the GNU General Public License, which is a copyleft
5817 license designed for free software.
5819 We have designed this License in order to use it for manuals for free
5820 software, because free software needs free documentation: a free
5821 program should come with manuals providing the same freedoms that the
5822 software does. But this License is not limited to software manuals;
5823 it can be used for any textual work, regardless of subject matter or
5824 whether it is published as a printed book. We recommend this License
5825 principally for works whose purpose is instruction or reference.
5828 1. APPLICABILITY AND DEFINITIONS
5830 This License applies to any manual or other work that contains a
5831 notice placed by the copyright holder saying it can be distributed
5832 under the terms of this License. The "Document", below, refers to any
5833 such manual or work. Any member of the public is a licensee, and is
5836 A "Modified Version" of the Document means any work containing the
5837 Document or a portion of it, either copied verbatim, or with
5838 modifications and/or translated into another language.
5840 A "Secondary Section" is a named appendix or a front-matter section of
5841 the Document that deals exclusively with the relationship of the
5842 publishers or authors of the Document to the Document's overall subject
5843 (or to related matters) and contains nothing that could fall directly
5844 within that overall subject. (For example, if the Document is in part a
5845 textbook of mathematics, a Secondary Section may not explain any
5846 mathematics.) The relationship could be a matter of historical
5847 connection with the subject or with related matters, or of legal,
5848 commercial, philosophical, ethical or political position regarding
5851 The "Invariant Sections" are certain Secondary Sections whose titles
5852 are designated, as being those of Invariant Sections, in the notice
5853 that says that the Document is released under this License.
5855 The "Cover Texts" are certain short passages of text that are listed,
5856 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
5857 the Document is released under this License.
5859 A "Transparent" copy of the Document means a machine-readable copy,
5860 represented in a format whose specification is available to the
5861 general public, whose contents can be viewed and edited directly and
5862 straightforwardly with generic text editors or (for images composed of
5863 pixels) generic paint programs or (for drawings) some widely available
5864 drawing editor, and that is suitable for input to text formatters or
5865 for automatic translation to a variety of formats suitable for input
5866 to text formatters. A copy made in an otherwise Transparent file
5867 format whose markup has been designed to thwart or discourage
5868 subsequent modification by readers is not Transparent. A copy that is
5869 not "Transparent" is called "Opaque".
5871 Examples of suitable formats for Transparent copies include plain
5872 ASCII without markup, Texinfo input format, LaTeX input format, SGML
5873 or XML using a publicly available DTD, and standard-conforming simple
5874 HTML designed for human modification. Opaque formats include
5875 PostScript, PDF, proprietary formats that can be read and edited only
5876 by proprietary word processors, SGML or XML for which the DTD and/or
5877 processing tools are not generally available, and the
5878 machine-generated HTML produced by some word processors for output
5881 The "Title Page" means, for a printed book, the title page itself,
5882 plus such following pages as are needed to hold, legibly, the material
5883 this License requires to appear in the title page. For works in
5884 formats which do not have any title page as such, "Title Page" means
5885 the text near the most prominent appearance of the work's title,
5886 preceding the beginning of the body of the text.
5891 You may copy and distribute the Document in any medium, either
5892 commercially or noncommercially, provided that this License, the
5893 copyright notices, and the license notice saying this License applies
5894 to the Document are reproduced in all copies, and that you add no other
5895 conditions whatsoever to those of this License. You may not use
5896 technical measures to obstruct or control the reading or further
5897 copying of the copies you make or distribute. However, you may accept
5898 compensation in exchange for copies. If you distribute a large enough
5899 number of copies you must also follow the conditions in section 3.
5901 You may also lend copies, under the same conditions stated above, and
5902 you may publicly display copies.
5905 3. COPYING IN QUANTITY
5907 If you publish printed copies of the Document numbering more than 100,
5908 and the Document's license notice requires Cover Texts, you must enclose
5909 the copies in covers that carry, clearly and legibly, all these Cover
5910 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
5911 the back cover. Both covers must also clearly and legibly identify
5912 you as the publisher of these copies. The front cover must present
5913 the full title with all words of the title equally prominent and
5914 visible. You may add other material on the covers in addition.
5915 Copying with changes limited to the covers, as long as they preserve
5916 the title of the Document and satisfy these conditions, can be treated
5917 as verbatim copying in other respects.
5919 If the required texts for either cover are too voluminous to fit
5920 legibly, you should put the first ones listed (as many as fit
5921 reasonably) on the actual cover, and continue the rest onto adjacent
5924 If you publish or distribute Opaque copies of the Document numbering
5925 more than 100, you must either include a machine-readable Transparent
5926 copy along with each Opaque copy, or state in or with each Opaque copy
5927 a publicly-accessible computer-network location containing a complete
5928 Transparent copy of the Document, free of added material, which the
5929 general network-using public has access to download anonymously at no
5930 charge using public-standard network protocols. If you use the latter
5931 option, you must take reasonably prudent steps, when you begin
5932 distribution of Opaque copies in quantity, to ensure that this
5933 Transparent copy will remain thus accessible at the stated location
5934 until at least one year after the last time you distribute an Opaque
5935 copy (directly or through your agents or retailers) of that edition to
5938 It is requested, but not required, that you contact the authors of the
5939 Document well before redistributing any large number of copies, to give
5940 them a chance to provide you with an updated version of the Document.
5945 You may copy and distribute a Modified Version of the Document under
5946 the conditions of sections 2 and 3 above, provided that you release
5947 the Modified Version under precisely this License, with the Modified
5948 Version filling the role of the Document, thus licensing distribution
5949 and modification of the Modified Version to whoever possesses a copy
5950 of it. In addition, you must do these things in the Modified Version:
5952 A. Use in the Title Page (and on the covers, if any) a title distinct
5953 from that of the Document, and from those of previous versions
5954 (which should, if there were any, be listed in the History section
5955 of the Document). You may use the same title as a previous version
5956 if the original publisher of that version gives permission.
5957 B. List on the Title Page, as authors, one or more persons or entities
5958 responsible for authorship of the modifications in the Modified
5959 Version, together with at least five of the principal authors of the
5960 Document (all of its principal authors, if it has less than five).
5961 C. State on the Title page the name of the publisher of the
5962 Modified Version, as the publisher.
5963 D. Preserve all the copyright notices of the Document.
5964 E. Add an appropriate copyright notice for your modifications
5965 adjacent to the other copyright notices.
5966 F. Include, immediately after the copyright notices, a license notice
5967 giving the public permission to use the Modified Version under the
5968 terms of this License, in the form shown in the Addendum below.
5969 G. Preserve in that license notice the full lists of Invariant Sections
5970 and required Cover Texts given in the Document's license notice.
5971 H. Include an unaltered copy of this License.
5972 I. Preserve the section entitled "History", and its title, and add to
5973 it an item stating at least the title, year, new authors, and
5974 publisher of the Modified Version as given on the Title Page. If
5975 there is no section entitled "History" in the Document, create one
5976 stating the title, year, authors, and publisher of the Document as
5977 given on its Title Page, then add an item describing the Modified
5978 Version as stated in the previous sentence.
5979 J. Preserve the network location, if any, given in the Document for
5980 public access to a Transparent copy of the Document, and likewise
5981 the network locations given in the Document for previous versions
5982 it was based on. These may be placed in the "History" section.
5983 You may omit a network location for a work that was published at
5984 least four years before the Document itself, or if the original
5985 publisher of the version it refers to gives permission.
5986 K. In any section entitled "Acknowledgements" or "Dedications",
5987 preserve the section's title, and preserve in the section all the
5988 substance and tone of each of the contributor acknowledgements
5989 and/or dedications given therein.
5990 L. Preserve all the Invariant Sections of the Document,
5991 unaltered in their text and in their titles. Section numbers
5992 or the equivalent are not considered part of the section titles.
5993 M. Delete any section entitled "Endorsements". Such a section
5994 may not be included in the Modified Version.
5995 N. Do not retitle any existing section as "Endorsements"
5996 or to conflict in title with any Invariant Section.
5998 If the Modified Version includes new front-matter sections or
5999 appendices that qualify as Secondary Sections and contain no material
6000 copied from the Document, you may at your option designate some or all
6001 of these sections as invariant. To do this, add their titles to the
6002 list of Invariant Sections in the Modified Version's license notice.
6003 These titles must be distinct from any other section titles.
6005 You may add a section entitled "Endorsements", provided it contains
6006 nothing but endorsements of your Modified Version by various
6007 parties--for example, statements of peer review or that the text has
6008 been approved by an organization as the authoritative definition of a
6011 You may add a passage of up to five words as a Front-Cover Text, and a
6012 passage of up to 25 words as a Back-Cover Text, to the end of the list
6013 of Cover Texts in the Modified Version. Only one passage of
6014 Front-Cover Text and one of Back-Cover Text may be added by (or
6015 through arrangements made by) any one entity. If the Document already
6016 includes a cover text for the same cover, previously added by you or
6017 by arrangement made by the same entity you are acting on behalf of,
6018 you may not add another; but you may replace the old one, on explicit
6019 permission from the previous publisher that added the old one.
6021 The author(s) and publisher(s) of the Document do not by this License
6022 give permission to use their names for publicity for or to assert or
6023 imply endorsement of any Modified Version.
6026 5. COMBINING DOCUMENTS
6028 You may combine the Document with other documents released under this
6029 License, under the terms defined in section 4 above for modified
6030 versions, provided that you include in the combination all of the
6031 Invariant Sections of all of the original documents, unmodified, and
6032 list them all as Invariant Sections of your combined work in its
6035 The combined work need only contain one copy of this License, and
6036 multiple identical Invariant Sections may be replaced with a single
6037 copy. If there are multiple Invariant Sections with the same name but
6038 different contents, make the title of each such section unique by
6039 adding at the end of it, in parentheses, the name of the original
6040 author or publisher of that section if known, or else a unique number.
6041 Make the same adjustment to the section titles in the list of
6042 Invariant Sections in the license notice of the combined work.
6044 In the combination, you must combine any sections entitled "History"
6045 in the various original documents, forming one section entitled
6046 "History"; likewise combine any sections entitled "Acknowledgements",
6047 and any sections entitled "Dedications". You must delete all sections
6048 entitled "Endorsements."
6051 6. COLLECTIONS OF DOCUMENTS
6053 You may make a collection consisting of the Document and other documents
6054 released under this License, and replace the individual copies of this
6055 License in the various documents with a single copy that is included in
6056 the collection, provided that you follow the rules of this License for
6057 verbatim copying of each of the documents in all other respects.
6059 You may extract a single document from such a collection, and distribute
6060 it individually under this License, provided you insert a copy of this
6061 License into the extracted document, and follow this License in all
6062 other respects regarding verbatim copying of that document.
6065 7. AGGREGATION WITH INDEPENDENT WORKS
6067 A compilation of the Document or its derivatives with other separate
6068 and independent documents or works, in or on a volume of a storage or
6069 distribution medium, does not as a whole count as a Modified Version
6070 of the Document, provided no compilation copyright is claimed for the
6071 compilation. Such a compilation is called an "aggregate", and this
6072 License does not apply to the other self-contained works thus compiled
6073 with the Document, on account of their being thus compiled, if they
6074 are not themselves derivative works of the Document.
6076 If the Cover Text requirement of section 3 is applicable to these
6077 copies of the Document, then if the Document is less than one quarter
6078 of the entire aggregate, the Document's Cover Texts may be placed on
6079 covers that surround only the Document within the aggregate.
6080 Otherwise they must appear on covers around the whole aggregate.
6085 Translation is considered a kind of modification, so you may
6086 distribute translations of the Document under the terms of section 4.
6087 Replacing Invariant Sections with translations requires special
6088 permission from their copyright holders, but you may include
6089 translations of some or all Invariant Sections in addition to the
6090 original versions of these Invariant Sections. You may include a
6091 translation of this License provided that you also include the
6092 original English version of this License. In case of a disagreement
6093 between the translation and the original English version of this
6094 License, the original English version will prevail.
6099 You may not copy, modify, sublicense, or distribute the Document except
6100 as expressly provided for under this License. Any other attempt to
6101 copy, modify, sublicense or distribute the Document is void, and will
6102 automatically terminate your rights under this License. However,
6103 parties who have received copies, or rights, from you under this
6104 License will not have their licenses terminated so long as such
6105 parties remain in full compliance.
6108 10. FUTURE REVISIONS OF THIS LICENSE
6110 The Free Software Foundation may publish new, revised versions
6111 of the GNU Free Documentation License from time to time. Such new
6112 versions will be similar in spirit to the present version, but may
6113 differ in detail to address new problems or concerns. See
6114 http://www.gnu.org/copyleft/.
6116 Each version of the License is given a distinguishing version number.
6117 If the Document specifies that a particular numbered version of this
6118 License "or any later version" applies to it, you have the option of
6119 following the terms and conditions either of that specified version or
6120 of any later version that has been published (not as a draft) by the
6121 Free Software Foundation. If the Document does not specify a version
6122 number of this License, you may choose any version ever published (not
6123 as a draft) by the Free Software Foundation.
6126 ADDENDUM: How to use this License for your documents
6128 To use this License in a document you have written, include a copy of
6129 the License in the document and put the following copyright and
6130 license notices just after the title page:
6133 Copyright (c) YEAR YOUR NAME.
6134 Permission is granted to copy, distribute and/or modify this document
6135 under the terms of the GNU Free Documentation License, Version 1.1
6136 or any later version published by the Free Software Foundation;
6137 with the Invariant Sections being LIST THEIR TITLES, with the
6138 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6139 A copy of the license is included in the section entitled "GNU
6140 Free Documentation License".
6143 If you have no Invariant Sections, write "with no Invariant Sections"
6144 instead of saying which ones are invariant. If you have no
6145 Front-Cover Texts, write "no Front-Cover Texts" instead of
6146 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6148 If your document contains nontrivial examples of program code, we
6149 recommend releasing these examples in parallel under your choice of
6150 free software license, such as the GNU General Public License,
6151 to permit their use in free software.
projects / deliverable / binutils-gdb.git / blob