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 ] [ -mips32 ]
280 [ -m4650 ] [ -no-m4650 ]
281 [ --trap ] [ --break ]
282 [ --emulation=@var{name} ]
284 [ -- | @var{files} @dots{} ]
289 Turn on listings, in any of a variety of ways:
293 omit false conditionals
296 omit debugging directives
299 include high-level source
305 include macro expansions
308 omit forms processing
314 set the name of the listing file
317 You may combine these options; for example, use @samp{-aln} for assembly
318 listing without forms processing. The @samp{=file} option, if used, must be
319 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
322 Ignored. This option is accepted for script compatibility with calls to
325 @item --defsym @var{sym}=@var{value}
326 Define the symbol @var{sym} to be @var{value} before assembling the input file.
327 @var{value} must be an integer constant. As in C, a leading @samp{0x}
328 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
331 ``fast''---skip whitespace and comment preprocessing (assume source is
335 Generate stabs debugging information for each assembler line. This
336 may help debugging assembler code, if the debugger can handle it.
339 Generate DWARF2 debugging information for each assembler line. This
340 may help debugging assembler code, if the debugger can handle it. Note - this
341 option is only supported by some targets, not all of them.
344 Print a summary of the command line options and exit.
347 Print a summary of all target specific options and exit.
350 Add directory @var{dir} to the search list for @code{.include} directives.
353 Don't warn about signed overflow.
356 @ifclear DIFF-TBL-KLUGE
357 This option is accepted but has no effect on the @value{TARGET} family.
359 @ifset DIFF-TBL-KLUGE
360 Issue warnings when difference tables altered for long displacements.
365 Keep (in the symbol table) local symbols. On traditional a.out systems
366 these start with @samp{L}, but different systems have different local
369 @item -o @var{objfile}
370 Name the object-file output from @code{@value{AS}} @var{objfile}.
373 Fold the data section into the text section.
376 Print the maximum space (in bytes) and total time (in seconds) used by
379 @item --strip-local-absolute
380 Remove local absolute symbols from the outgoing symbol table.
384 Print the @code{as} version.
387 Print the @code{as} version and exit.
391 Suppress warning messages.
393 @item --fatal-warnings
394 Treat warnings as errors.
397 Don't suppress warning messages or treat them as errors.
406 Generate an object file even after errors.
408 @item -- | @var{files} @dots{}
409 Standard input, or source files to assemble.
414 The following options are available when @value{AS} is configured for
419 @cindex ARC endianness
420 @cindex endianness, ARC
421 @cindex big endian output, ARC
423 Generate ``big endian'' format output.
425 @cindex little endian output, ARC
426 @item -mlittle-endian
427 Generate ``little endian'' format output.
433 The following options are available when @value{AS} is configured for the ARM
437 @item -m[arm][1|2|3|6|7|8|9][...]
438 Specify which ARM processor variant is the target.
439 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
440 Specify which ARM architecture variant is used by the target.
441 @item -mthumb | -mall
442 Enable or disable Thumb only instruction decoding.
443 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
444 Select which Floating Point architcture is the target.
445 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
446 Select which procedure calling convention is in use.
448 Select either big-endian (-EB) or little-endian (-EL) output.
449 @item -mthumb-interwork
450 Specify that the code has been generated with interworking between Thumb and
453 Specify that PIC code has been generated.
458 The following options are available when @value{AS} is configured for
461 @cindex D10V optimization
462 @cindex optimization, D10V
464 Optimize output by parallelizing instructions.
469 The following options are available when @value{AS} is configured for a D30V
472 @cindex D30V optimization
473 @cindex optimization, D30V
475 Optimize output by parallelizing instructions.
479 Warn when nops are generated.
481 @cindex D30V nops after 32-bit multiply
483 Warn when a nop after a 32-bit multiply instruction is generated.
488 The following options are available when @value{AS} is configured for the
489 Intel 80960 processor.
492 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
493 Specify which variant of the 960 architecture is the target.
496 Add code to collect statistics about branches taken.
499 Do not alter compare-and-branch instructions for long displacements;
506 The following options are available when @value{AS} is configured for the
507 Mitsubishi M32R series.
512 Specify which processor in the M32R family is the target. The default
513 is normally the M32R, but this option changes it to the M32RX.
515 @item --warn-explicit-parallel-conflicts or --Wp
516 Produce warning messages when questionable parallel constructs are
519 @item --no-warn-explicit-parallel-conflicts or --Wnp
520 Do not produce warning messages when questionable parallel constructs are
527 The following options are available when @value{AS} is configured for the
528 Motorola 68000 series.
533 Shorten references to undefined symbols, to one word instead of two.
535 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060
536 @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200
537 Specify what processor in the 68000 family is the target. The default
538 is normally the 68020, but this can be changed at configuration time.
540 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
541 The target machine does (or does not) have a floating-point coprocessor.
542 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
543 the basic 68000 is not compatible with the 68881, a combination of the
544 two can be specified, since it's possible to do emulation of the
545 coprocessor instructions with the main processor.
547 @item -m68851 | -mno-68851
548 The target machine does (or does not) have a memory-management
549 unit coprocessor. The default is to assume an MMU for 68020 and up.
555 The following options are available when @value{AS} is configured for
556 a picoJava processor.
560 @cindex PJ endianness
561 @cindex endianness, PJ
562 @cindex big endian output, PJ
564 Generate ``big endian'' format output.
566 @cindex little endian output, PJ
568 Generate ``little endian'' format output.
574 The following options are available when @value{AS} is configured for the
575 Motorola 68HC11 or 68HC12 series.
579 @item -m68hc11 | -m68hc12
580 Specify what processor is the target. The default is
581 defined by the configuration option when building the assembler.
583 @item --force-long-branchs
584 Relative branches are turned into absolute ones. This concerns
585 conditional branches, unconditional branches and branches to a
588 @item -S | --short-branchs
589 Do not turn relative branchs into absolute ones
590 when the offset is out of range.
592 @item --strict-direct-mode
593 Do not turn the direct addressing mode into extended addressing mode
594 when the instruction does not support direct addressing mode.
596 @item --print-insn-syntax
597 Print the syntax of instruction in case of error.
599 @item --print-opcodes
600 print the list of instructions with syntax and then exit.
602 @item --generate-example
603 print an example of instruction for each possible instruction and then exit.
604 This option is only useful for testing @code{@value{AS}}.
610 The following options are available when @code{@value{AS}} is configured
611 for the SPARC architecture:
614 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
615 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
616 Explicitly select a variant of the SPARC architecture.
618 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
619 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
621 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
622 UltraSPARC extensions.
624 @item -xarch=v8plus | -xarch=v8plusa
625 For compatibility with the Solaris v9 assembler. These options are
626 equivalent to -Av8plus and -Av8plusa, respectively.
629 Warn when the assembler switches to another architecture.
634 The following options are available when @value{AS} is configured for the 'c54x
639 Enable extended addressing mode. All addresses and relocations will assume
640 extended addressing (usually 23 bits).
641 @item -mcpu=@var{CPU_VERSION}
642 Sets the CPU version being compiled for.
643 @item -merrors-to-file @var{FILENAME}
644 Redirect error output to a file, for broken systems which don't support such
645 behaviour in the shell.
650 The following options are available when @value{AS} is configured for
655 This option sets the largest size of an object that can be referenced
656 implicitly with the @code{gp} register. It is only accepted for targets that
657 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
659 @cindex MIPS endianness
660 @cindex endianness, MIPS
661 @cindex big endian output, MIPS
663 Generate ``big endian'' format output.
665 @cindex little endian output, MIPS
667 Generate ``little endian'' format output.
675 Generate code for a particular MIPS Instruction Set Architecture level.
676 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
677 @samp{-mips2} to the @sc{r6000} processor, @samp{-mips3} to the @sc{r4000}
678 processor, @samp{-mips32} to a generic @sc{MIPS32} processor.
682 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
683 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
684 instructions around accesses to the @samp{HI} and @samp{LO} registers.
685 @samp{-no-m4650} turns off this option.
687 @item -mcpu=@var{CPU}
688 Generate code for a particular MIPS cpu. This has little effect on the
689 assembler, but it is passed by @code{@value{GCC}}.
692 @item --emulation=@var{name}
693 This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured
694 for some other target, in all respects, including output format (choosing
695 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
696 debugging information or store symbol table information, and default
697 endianness. The available configuration names are: @samp{mipsecoff},
698 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
699 @samp{mipsbelf}. The first two do not alter the default endianness from that
700 of the primary target for which the assembler was configured; the others change
701 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
702 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
703 selection in any case.
705 This option is currently supported only when the primary target
706 @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
707 Furthermore, the primary target or others specified with
708 @samp{--enable-targets=@dots{}} at configuration time must include support for
709 the other format, if both are to be available. For example, the Irix 5
710 configuration includes support for both.
712 Eventually, this option will support more configurations, with more
713 fine-grained control over the assembler's behavior, and will be supported for
717 @code{@value{AS}} ignores this option. It is accepted for compatibility with
725 Control how to deal with multiplication overflow and division by zero.
726 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
727 (and only work for Instruction Set Architecture level 2 and higher);
728 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
734 The following options are available when @value{AS} is configured for
740 Enable or disable the JSRI to BSR transformation. By default this is enabled.
741 The command line option @samp{-nojsri2bsr} can be used to disable it.
745 Enable or disable the silicon filter behaviour. By default this is disabled.
746 The default can be overidden by the @samp{-sifilter} command line option.
749 Alter jump instructions for long displacements.
751 @item -mcpu=[210|340]
752 Select the cpu type on the target hardware. This controls which instructions
756 Assemble for a big endian target.
759 Assemble for a little endian target.
765 * Manual:: Structure of this Manual
766 * GNU Assembler:: The GNU Assembler
767 * Object Formats:: Object File Formats
768 * Command Line:: Command Line
769 * Input Files:: Input Files
770 * Object:: Output (Object) File
771 * Errors:: Error and Warning Messages
775 @section Structure of this Manual
777 @cindex manual, structure and purpose
778 This manual is intended to describe what you need to know to use
779 @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
780 notation for symbols, constants, and expressions; the directives that
781 @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
784 We also cover special features in the @value{TARGET}
785 configuration of @code{@value{AS}}, including assembler directives.
788 This manual also describes some of the machine-dependent features of
789 various flavors of the assembler.
792 @cindex machine instructions (not covered)
793 On the other hand, this manual is @emph{not} intended as an introduction
794 to programming in assembly language---let alone programming in general!
795 In a similar vein, we make no attempt to introduce the machine
796 architecture; we do @emph{not} describe the instruction set, standard
797 mnemonics, registers or addressing modes that are standard to a
798 particular architecture.
800 You may want to consult the manufacturer's
801 machine architecture manual for this information.
805 For information on the H8/300 machine instruction set, see @cite{H8/300
806 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
807 see @cite{H8/300H Series Programming Manual} (Hitachi).
810 For information on the H8/500 machine instruction set, see @cite{H8/500
811 Series Programming Manual} (Hitachi M21T001).
814 For information on the Hitachi SH machine instruction set, see
815 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
818 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
822 @c I think this is premature---doc@cygnus.com, 17jan1991
824 Throughout this manual, we assume that you are running @dfn{GNU},
825 the portable operating system from the @dfn{Free Software
826 Foundation, Inc.}. This restricts our attention to certain kinds of
827 computer (in particular, the kinds of computers that @sc{gnu} can run on);
828 once this assumption is granted examples and definitions need less
831 @code{@value{AS}} is part of a team of programs that turn a high-level
832 human-readable series of instructions into a low-level
833 computer-readable series of instructions. Different versions of
834 @code{@value{AS}} are used for different kinds of computer.
837 @c There used to be a section "Terminology" here, which defined
838 @c "contents", "byte", "word", and "long". Defining "word" to any
839 @c particular size is confusing when the .word directive may generate 16
840 @c bits on one machine and 32 bits on another; in general, for the user
841 @c version of this manual, none of these terms seem essential to define.
842 @c They were used very little even in the former draft of the manual;
843 @c this draft makes an effort to avoid them (except in names of
847 @section The GNU Assembler
849 @sc{gnu} @code{as} is really a family of assemblers.
851 This manual describes @code{@value{AS}}, a member of that family which is
852 configured for the @value{TARGET} architectures.
854 If you use (or have used) the @sc{gnu} assembler on one architecture, you
855 should find a fairly similar environment when you use it on another
856 architecture. Each version has much in common with the others,
857 including object file formats, most assembler directives (often called
858 @dfn{pseudo-ops}) and assembler syntax.@refill
860 @cindex purpose of @sc{gnu} assembler
861 @code{@value{AS}} is primarily intended to assemble the output of the
862 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
863 @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
864 assemble correctly everything that other assemblers for the same
865 machine would assemble.
867 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
870 @c This remark should appear in generic version of manual; assumption
871 @c here is that generic version sets M680x0.
872 This doesn't mean @code{@value{AS}} always uses the same syntax as another
873 assembler for the same architecture; for example, we know of several
874 incompatible versions of 680x0 assembly language syntax.
877 Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
878 program in one pass of the source file. This has a subtle impact on the
879 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
882 @section Object File Formats
884 @cindex object file format
885 The @sc{gnu} assembler can be configured to produce several alternative
886 object file formats. For the most part, this does not affect how you
887 write assembly language programs; but directives for debugging symbols
888 are typically different in different file formats. @xref{Symbol
889 Attributes,,Symbol Attributes}.
892 On the @value{TARGET}, @code{@value{AS}} is configured to produce
893 @value{OBJ-NAME} format object files.
895 @c The following should exhaust all configs that set MULTI-OBJ, ideally
897 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
898 @code{a.out} or COFF format object files.
901 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
902 @code{b.out} or COFF format object files.
905 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
906 SOM or ELF format object files.
911 @section Command Line
913 @cindex command line conventions
914 After the program name @code{@value{AS}}, the command line may contain
915 options and file names. Options may appear in any order, and may be
916 before, after, or between file names. The order of file names is
919 @cindex standard input, as input file
921 @file{--} (two hyphens) by itself names the standard input file
922 explicitly, as one of the files for @code{@value{AS}} to assemble.
924 @cindex options, command line
925 Except for @samp{--} any command line argument that begins with a
926 hyphen (@samp{-}) is an option. Each option changes the behavior of
927 @code{@value{AS}}. No option changes the way another option works. An
928 option is a @samp{-} followed by one or more letters; the case of
929 the letter is important. All options are optional.
931 Some options expect exactly one file name to follow them. The file
932 name may either immediately follow the option's letter (compatible
933 with older assemblers) or it may be the next command argument (@sc{gnu}
934 standard). These two command lines are equivalent:
937 @value{AS} -o my-object-file.o mumble.s
938 @value{AS} -omy-object-file.o mumble.s
945 @cindex source program
947 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
948 describe the program input to one run of @code{@value{AS}}. The program may
949 be in one or more files; how the source is partitioned into files
950 doesn't change the meaning of the source.
952 @c I added "con" prefix to "catenation" just to prove I can overcome my
953 @c APL training... doc@cygnus.com
954 The source program is a concatenation of the text in all the files, in the
957 Each time you run @code{@value{AS}} it assembles exactly one source
958 program. The source program is made up of one or more files.
959 (The standard input is also a file.)
961 You give @code{@value{AS}} a command line that has zero or more input file
962 names. The input files are read (from left file name to right). A
963 command line argument (in any position) that has no special meaning
964 is taken to be an input file name.
966 If you give @code{@value{AS}} no file names it attempts to read one input file
967 from the @code{@value{AS}} standard input, which is normally your terminal. You
968 may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
971 Use @samp{--} if you need to explicitly name the standard input file
972 in your command line.
974 If the source is empty, @code{@value{AS}} produces a small, empty object
977 @subheading Filenames and Line-numbers
979 @cindex input file linenumbers
980 @cindex line numbers, in input files
981 There are two ways of locating a line in the input file (or files) and
982 either may be used in reporting error messages. One way refers to a line
983 number in a physical file; the other refers to a line number in a
984 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
986 @dfn{Physical files} are those files named in the command line given
987 to @code{@value{AS}}.
989 @dfn{Logical files} are simply names declared explicitly by assembler
990 directives; they bear no relation to physical files. Logical file names help
991 error messages reflect the original source file, when @code{@value{AS}} source
992 is itself synthesized from other files. @code{@value{AS}} understands the
993 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
994 @ref{File,,@code{.file}}.
997 @section Output (Object) File
1003 Every time you run @code{@value{AS}} it produces an output file, which is
1004 your assembly language program translated into numbers. This file
1005 is the object file. Its default name is
1013 @code{b.out} when @code{@value{AS}} is configured for the Intel 80960.
1015 You can give it another name by using the @code{-o} option. Conventionally,
1016 object file names end with @file{.o}. The default name is used for historical
1017 reasons: older assemblers were capable of assembling self-contained programs
1018 directly into a runnable program. (For some formats, this isn't currently
1019 possible, but it can be done for the @code{a.out} format.)
1023 The object file is meant for input to the linker @code{@value{LD}}. It contains
1024 assembled program code, information to help @code{@value{LD}} integrate
1025 the assembled program into a runnable file, and (optionally) symbolic
1026 information for the debugger.
1028 @c link above to some info file(s) like the description of a.out.
1029 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1032 @section Error and Warning Messages
1034 @cindex error messsages
1035 @cindex warning messages
1036 @cindex messages from assembler
1037 @code{@value{AS}} may write warnings and error messages to the standard error
1038 file (usually your terminal). This should not happen when a compiler
1039 runs @code{@value{AS}} automatically. Warnings report an assumption made so
1040 that @code{@value{AS}} could keep assembling a flawed program; errors report a
1041 grave problem that stops the assembly.
1043 @cindex format of warning messages
1044 Warning messages have the format
1047 file_name:@b{NNN}:Warning Message Text
1051 @cindex line numbers, in warnings/errors
1052 (where @b{NNN} is a line number). If a logical file name has been given
1053 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1054 the current input file is used. If a logical line number was given
1056 (@pxref{Line,,@code{.line}})
1060 (@pxref{Line,,@code{.line}})
1063 (@pxref{Ln,,@code{.ln}})
1066 then it is used to calculate the number printed,
1067 otherwise the actual line in the current source file is printed. The
1068 message text is intended to be self explanatory (in the grand Unix
1071 @cindex format of error messages
1072 Error messages have the format
1074 file_name:@b{NNN}:FATAL:Error Message Text
1076 The file name and line number are derived as for warning
1077 messages. The actual message text may be rather less explanatory
1078 because many of them aren't supposed to happen.
1081 @chapter Command-Line Options
1083 @cindex options, all versions of assembler
1084 This chapter describes command-line options available in @emph{all}
1085 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1087 to the @value{TARGET}.
1090 to particular machine architectures.
1093 If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2),
1094 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1095 The assembler arguments must be separated from each other (and the @samp{-Wa})
1096 by commas. For example:
1099 gcc -c -g -O -Wa,-alh,-L file.c
1103 This passes two options to the assembler: @samp{-alh} (emit a listing to
1104 standard output with with high-level and assembly source) and @samp{-L} (retain
1105 local symbols in the symbol table).
1107 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1108 command-line options are automatically passed to the assembler by the compiler.
1109 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1110 precisely what options it passes to each compilation pass, including the
1114 * a:: -a[cdhlns] enable listings
1115 * D:: -D for compatibility
1116 * f:: -f to work faster
1117 * I:: -I for .include search path
1118 @ifclear DIFF-TBL-KLUGE
1119 * K:: -K for compatibility
1121 @ifset DIFF-TBL-KLUGE
1122 * K:: -K for difference tables
1125 * L:: -L to retain local labels
1126 * M:: -M or --mri to assemble in MRI compatibility mode
1127 * MD:: --MD for dependency tracking
1128 * o:: -o to name the object file
1129 * R:: -R to join data and text sections
1130 * statistics:: --statistics to see statistics about assembly
1131 * traditional-format:: --traditional-format for compatible output
1132 * v:: -v to announce version
1133 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1134 * Z:: -Z to make object file even after errors
1138 @section Enable Listings: @code{-a[cdhlns]}
1147 @cindex listings, enabling
1148 @cindex assembly listings, enabling
1150 These options enable listing output from the assembler. By itself,
1151 @samp{-a} requests high-level, assembly, and symbols listing.
1152 You can use other letters to select specific options for the list:
1153 @samp{-ah} requests a high-level language listing,
1154 @samp{-al} requests an output-program assembly listing, and
1155 @samp{-as} requests a symbol table listing.
1156 High-level listings require that a compiler debugging option like
1157 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1160 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1161 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1162 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1163 omitted from the listing.
1165 Use the @samp{-ad} option to omit debugging directives from the
1168 Once you have specified one of these options, you can further control
1169 listing output and its appearance using the directives @code{.list},
1170 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1172 The @samp{-an} option turns off all forms processing.
1173 If you do not request listing output with one of the @samp{-a} options, the
1174 listing-control directives have no effect.
1176 The letters after @samp{-a} may be combined into one option,
1177 @emph{e.g.}, @samp{-aln}.
1183 This option has no effect whatsoever, but it is accepted to make it more
1184 likely that scripts written for other assemblers also work with
1188 @section Work Faster: @code{-f}
1191 @cindex trusted compiler
1192 @cindex faster processing (@code{-f})
1193 @samp{-f} should only be used when assembling programs written by a
1194 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1195 and comment preprocessing on
1196 the input file(s) before assembling them. @xref{Preprocessing,
1200 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1201 preprocessed (if they contain comments, for example), @code{@value{AS}} does
1206 @section @code{.include} search path: @code{-I} @var{path}
1208 @kindex -I @var{path}
1209 @cindex paths for @code{.include}
1210 @cindex search path for @code{.include}
1211 @cindex @code{include} directive search path
1212 Use this option to add a @var{path} to the list of directories
1213 @code{@value{AS}} searches for files specified in @code{.include}
1214 directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
1215 many times as necessary to include a variety of paths. The current
1216 working directory is always searched first; after that, @code{@value{AS}}
1217 searches any @samp{-I} directories in the same order as they were
1218 specified (left to right) on the command line.
1221 @section Difference Tables: @code{-K}
1224 @ifclear DIFF-TBL-KLUGE
1225 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1226 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1227 where it can be used to warn when the assembler alters the machine code
1228 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1229 family does not have the addressing limitations that sometimes lead to this
1230 alteration on other platforms.
1233 @ifset DIFF-TBL-KLUGE
1234 @cindex difference tables, warning
1235 @cindex warning for altered difference tables
1236 @code{@value{AS}} sometimes alters the code emitted for directives of the form
1237 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1238 You can use the @samp{-K} option if you want a warning issued when this
1243 @section Include Local Labels: @code{-L}
1246 @cindex local labels, retaining in output
1247 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1248 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1249 debugging, because they are intended for the use of programs (like
1250 compilers) that compose assembler programs, not for your notice.
1251 Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1252 normally debug with them.
1254 This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
1255 in the object file. Usually if you do this you also tell the linker
1256 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1258 By default, a local label is any label beginning with @samp{L}, but each
1259 target is allowed to redefine the local label prefix.
1261 On the HPPA local labels begin with @samp{L$}.
1265 @section Assemble in MRI Compatibility Mode: @code{-M}
1268 @cindex MRI compatibility mode
1269 The @code{-M} or @code{--mri} option selects MRI compatibility mode. This
1270 changes the syntax and pseudo-op handling of @code{@value{AS}} to make it
1271 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1272 configured target) assembler from Microtec Research. The exact nature of the
1273 MRI syntax will not be documented here; see the MRI manuals for more
1274 information. Note in particular that the handling of macros and macro
1275 arguments is somewhat different. The purpose of this option is to permit
1276 assembling existing MRI assembler code using @code{@value{AS}}.
1278 The MRI compatibility is not complete. Certain operations of the MRI assembler
1279 depend upon its object file format, and can not be supported using other object
1280 file formats. Supporting these would require enhancing each object file format
1281 individually. These are:
1284 @item global symbols in common section
1286 The m68k MRI assembler supports common sections which are merged by the linker.
1287 Other object file formats do not support this. @code{@value{AS}} handles
1288 common sections by treating them as a single common symbol. It permits local
1289 symbols to be defined within a common section, but it can not support global
1290 symbols, since it has no way to describe them.
1292 @item complex relocations
1294 The MRI assemblers support relocations against a negated section address, and
1295 relocations which combine the start addresses of two or more sections. These
1296 are not support by other object file formats.
1298 @item @code{END} pseudo-op specifying start address
1300 The MRI @code{END} pseudo-op permits the specification of a start address.
1301 This is not supported by other object file formats. The start address may
1302 instead be specified using the @code{-e} option to the linker, or in a linker
1305 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1307 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1308 name to the output file. This is not supported by other object file formats.
1310 @item @code{ORG} pseudo-op
1312 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1313 address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op,
1314 which changes the location within the current section. Absolute sections are
1315 not supported by other object file formats. The address of a section may be
1316 assigned within a linker script.
1319 There are some other features of the MRI assembler which are not supported by
1320 @code{@value{AS}}, typically either because they are difficult or because they
1321 seem of little consequence. Some of these may be supported in future releases.
1325 @item EBCDIC strings
1327 EBCDIC strings are not supported.
1329 @item packed binary coded decimal
1331 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1332 and @code{DCB.P} pseudo-ops are not supported.
1334 @item @code{FEQU} pseudo-op
1336 The m68k @code{FEQU} pseudo-op is not supported.
1338 @item @code{NOOBJ} pseudo-op
1340 The m68k @code{NOOBJ} pseudo-op is not supported.
1342 @item @code{OPT} branch control options
1344 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1345 @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically
1346 relaxes all branches, whether forward or backward, to an appropriate size, so
1347 these options serve no purpose.
1349 @item @code{OPT} list control options
1351 The following m68k @code{OPT} list control options are ignored: @code{C},
1352 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1353 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1355 @item other @code{OPT} options
1357 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1358 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1360 @item @code{OPT} @code{D} option is default
1362 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1363 @code{OPT NOD} may be used to turn it off.
1365 @item @code{XREF} pseudo-op.
1367 The m68k @code{XREF} pseudo-op is ignored.
1369 @item @code{.debug} pseudo-op
1371 The i960 @code{.debug} pseudo-op is not supported.
1373 @item @code{.extended} pseudo-op
1375 The i960 @code{.extended} pseudo-op is not supported.
1377 @item @code{.list} pseudo-op.
1379 The various options of the i960 @code{.list} pseudo-op are not supported.
1381 @item @code{.optimize} pseudo-op
1383 The i960 @code{.optimize} pseudo-op is not supported.
1385 @item @code{.output} pseudo-op
1387 The i960 @code{.output} pseudo-op is not supported.
1389 @item @code{.setreal} pseudo-op
1391 The i960 @code{.setreal} pseudo-op is not supported.
1396 @section Dependency tracking: @code{--MD}
1399 @cindex dependency tracking
1402 @code{@value{AS}} can generate a dependency file for the file it creates. This
1403 file consists of a single rule suitable for @code{make} describing the
1404 dependencies of the main source file.
1406 The rule is written to the file named in its argument.
1408 This feature is used in the automatic updating of makefiles.
1411 @section Name the Object File: @code{-o}
1414 @cindex naming object file
1415 @cindex object file name
1416 There is always one object file output when you run @code{@value{AS}}. By
1417 default it has the name
1420 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1434 You use this option (which takes exactly one filename) to give the
1435 object file a different name.
1437 Whatever the object file is called, @code{@value{AS}} overwrites any
1438 existing file of the same name.
1441 @section Join Data and Text Sections: @code{-R}
1444 @cindex data and text sections, joining
1445 @cindex text and data sections, joining
1446 @cindex joining text and data sections
1447 @cindex merging text and data sections
1448 @code{-R} tells @code{@value{AS}} to write the object file as if all
1449 data-section data lives in the text section. This is only done at
1450 the very last moment: your binary data are the same, but data
1451 section parts are relocated differently. The data section part of
1452 your object file is zero bytes long because all its bytes are
1453 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1455 When you specify @code{-R} it would be possible to generate shorter
1456 address displacements (because we do not have to cross between text and
1457 data section). We refrain from doing this simply for compatibility with
1458 older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
1461 When @code{@value{AS}} is configured for COFF output,
1462 this option is only useful if you use sections named @samp{.text} and
1467 @code{-R} is not supported for any of the HPPA targets. Using
1468 @code{-R} generates a warning from @code{@value{AS}}.
1472 @section Display Assembly Statistics: @code{--statistics}
1474 @kindex --statistics
1475 @cindex statistics, about assembly
1476 @cindex time, total for assembly
1477 @cindex space used, maximum for assembly
1478 Use @samp{--statistics} to display two statistics about the resources used by
1479 @code{@value{AS}}: the maximum amount of space allocated during the assembly
1480 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1483 @node traditional-format
1484 @section Compatible output: @code{--traditional-format}
1486 @kindex --traditional-format
1487 For some targets, the output of @code{@value{AS}} is different in some ways
1488 from the output of some existing assembler. This switch requests
1489 @code{@value{AS}} to use the traditional format instead.
1491 For example, it disables the exception frame optimizations which
1492 @code{@value{AS}} normally does by default on @code{@value{GCC}} output.
1495 @section Announce Version: @code{-v}
1499 @cindex assembler version
1500 @cindex version of assembler
1501 You can find out what version of as is running by including the
1502 option @samp{-v} (which you can also spell as @samp{-version}) on the
1506 @section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings}
1508 @code{@value{AS}} should never give a warning or error message when
1509 assembling compiler output. But programs written by people often
1510 cause @code{@value{AS}} to give a warning that a particular assumption was
1511 made. All such warnings are directed to the standard error file.
1514 @kindex @samp{--no-warn}
1515 @cindex suppressing warnings
1516 @cindex warnings, suppressing
1517 If you use the @code{-W} and @code{--no-warn} options, no warnings are issued.
1518 This only affects the warning messages: it does not change any particular of
1519 how @code{@value{AS}} assembles your file. Errors, which stop the assembly,
1522 @kindex @samp{--fatal-warnings}
1523 @cindex errors, caused by warnings
1524 @cindex warnings, causing error
1525 If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers
1526 files that generate warnings to be in error.
1528 @kindex @samp{--warn}
1529 @cindex warnings, switching on
1530 You can switch these options off again by specifying @code{--warn}, which
1531 causes warnings to be output as usual.
1534 @section Generate Object File in Spite of Errors: @code{-Z}
1535 @cindex object file, after errors
1536 @cindex errors, continuing after
1537 After an error message, @code{@value{AS}} normally produces no output. If for
1538 some reason you are interested in object file output even after
1539 @code{@value{AS}} gives an error message on your program, use the @samp{-Z}
1540 option. If there are any errors, @code{@value{AS}} continues anyways, and
1541 writes an object file after a final warning message of the form @samp{@var{n}
1542 errors, @var{m} warnings, generating bad object file.}
1547 @cindex machine-independent syntax
1548 @cindex syntax, machine-independent
1549 This chapter describes the machine-independent syntax allowed in a
1550 source file. @code{@value{AS}} syntax is similar to what many other
1551 assemblers use; it is inspired by the BSD 4.2
1556 assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
1560 * Preprocessing:: Preprocessing
1561 * Whitespace:: Whitespace
1562 * Comments:: Comments
1563 * Symbol Intro:: Symbols
1564 * Statements:: Statements
1565 * Constants:: Constants
1569 @section Preprocessing
1571 @cindex preprocessing
1572 The @code{@value{AS}} internal preprocessor:
1574 @cindex whitespace, removed by preprocessor
1576 adjusts and removes extra whitespace. It leaves one space or tab before
1577 the keywords on a line, and turns any other whitespace on the line into
1580 @cindex comments, removed by preprocessor
1582 removes all comments, replacing them with a single space, or an
1583 appropriate number of newlines.
1585 @cindex constants, converted by preprocessor
1587 converts character constants into the appropriate numeric values.
1590 It does not do macro processing, include file handling, or
1591 anything else you may get from your C compiler's preprocessor. You can
1592 do include file processing with the @code{.include} directive
1593 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1594 to get other ``CPP'' style preprocessing, by giving the input file a
1595 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1596 Output, gcc.info, Using GNU CC}.
1598 Excess whitespace, comments, and character constants
1599 cannot be used in the portions of the input text that are not
1602 @cindex turning preprocessing on and off
1603 @cindex preprocessing, turning on and off
1606 If the first line of an input file is @code{#NO_APP} or if you use the
1607 @samp{-f} option, whitespace and comments are not removed from the input file.
1608 Within an input file, you can ask for whitespace and comment removal in
1609 specific portions of the by putting a line that says @code{#APP} before the
1610 text that may contain whitespace or comments, and putting a line that says
1611 @code{#NO_APP} after this text. This feature is mainly intend to support
1612 @code{asm} statements in compilers whose output is otherwise free of comments
1619 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1620 Whitespace is used to separate symbols, and to make programs neater for
1621 people to read. Unless within character constants
1622 (@pxref{Characters,,Character Constants}), any whitespace means the same
1623 as exactly one space.
1629 There are two ways of rendering comments to @code{@value{AS}}. In both
1630 cases the comment is equivalent to one space.
1632 Anything from @samp{/*} through the next @samp{*/} is a comment.
1633 This means you may not nest these comments.
1637 The only way to include a newline ('\n') in a comment
1638 is to use this sort of comment.
1641 /* This sort of comment does not nest. */
1644 @cindex line comment character
1645 Anything from the @dfn{line comment} character to the next newline
1646 is considered a comment and is ignored. The line comment character is
1648 @samp{;} for the AMD 29K family;
1651 @samp{;} on the ARC;
1654 @samp{@@} on the ARM;
1657 @samp{;} for the H8/300 family;
1660 @samp{!} for the H8/500 family;
1663 @samp{;} for the HPPA;
1666 @samp{#} on the i960;
1669 @samp{;} for picoJava;
1672 @samp{!} for the Hitachi SH;
1675 @samp{!} on the SPARC;
1678 @samp{#} on the m32r;
1681 @samp{|} on the 680x0;
1684 @samp{#} on the 68HC11 and 68HC12;
1687 @samp{#} on the Vax;
1690 @samp{!} for the Z8000;
1693 @samp{#} on the V850;
1695 see @ref{Machine Dependencies}. @refill
1696 @c FIXME What about i386, m88k, i860?
1699 On some machines there are two different line comment characters. One
1700 character only begins a comment if it is the first non-whitespace character on
1701 a line, while the other always begins a comment.
1705 The V850 assembler also supports a double dash as starting a comment that
1706 extends to the end of the line.
1712 @cindex lines starting with @code{#}
1713 @cindex logical line numbers
1714 To be compatible with past assemblers, lines that begin with @samp{#} have a
1715 special interpretation. Following the @samp{#} should be an absolute
1716 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1717 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1718 new logical file name. The rest of the line, if any, should be whitespace.
1720 If the first non-whitespace characters on the line are not numeric,
1721 the line is ignored. (Just like a comment.)
1724 # This is an ordinary comment.
1725 # 42-6 "new_file_name" # New logical file name
1726 # This is logical line # 36.
1728 This feature is deprecated, and may disappear from future versions
1729 of @code{@value{AS}}.
1734 @cindex characters used in symbols
1735 @ifclear SPECIAL-SYMS
1736 A @dfn{symbol} is one or more characters chosen from the set of all
1737 letters (both upper and lower case), digits and the three characters
1743 A @dfn{symbol} is one or more characters chosen from the set of all
1744 letters (both upper and lower case), digits and the three characters
1745 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
1751 On most machines, you can also use @code{$} in symbol names; exceptions
1752 are noted in @ref{Machine Dependencies}.
1754 No symbol may begin with a digit. Case is significant.
1755 There is no length limit: all characters are significant. Symbols are
1756 delimited by characters not in that set, or by the beginning of a file
1757 (since the source program must end with a newline, the end of a file is
1758 not a possible symbol delimiter). @xref{Symbols}.
1759 @cindex length of symbols
1764 @cindex statements, structure of
1765 @cindex line separator character
1766 @cindex statement separator character
1768 @ifclear abnormal-separator
1769 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
1770 semicolon (@samp{;}). The newline or semicolon is considered part of
1771 the preceding statement. Newlines and semicolons within character
1772 constants are an exception: they do not end statements.
1774 @ifset abnormal-separator
1776 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
1777 sign (@samp{@@}). The newline or at sign is considered part of the
1778 preceding statement. Newlines and at signs within character constants
1779 are an exception: they do not end statements.
1782 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
1783 point (@samp{!}). The newline or exclamation point is considered part of the
1784 preceding statement. Newlines and exclamation points within character
1785 constants are an exception: they do not end statements.
1788 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
1789 H8/300) a dollar sign (@samp{$}); or (for the
1792 (@samp{;}). The newline or separator character is considered part of
1793 the preceding statement. Newlines and separators within character
1794 constants are an exception: they do not end statements.
1799 A @dfn{statement} ends at a newline character (@samp{\n}) or line
1800 separator character. (The line separator is usually @samp{;}, unless
1801 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
1802 newline or separator character is considered part of the preceding
1803 statement. Newlines and separators within character constants are an
1804 exception: they do not end statements.
1807 @cindex newline, required at file end
1808 @cindex EOF, newline must precede
1809 It is an error to end any statement with end-of-file: the last
1810 character of any input file should be a newline.@refill
1812 An empty statement is allowed, and may include whitespace. It is ignored.
1814 @cindex instructions and directives
1815 @cindex directives and instructions
1816 @c "key symbol" is not used elsewhere in the document; seems pedantic to
1817 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
1819 A statement begins with zero or more labels, optionally followed by a
1820 key symbol which determines what kind of statement it is. The key
1821 symbol determines the syntax of the rest of the statement. If the
1822 symbol begins with a dot @samp{.} then the statement is an assembler
1823 directive: typically valid for any computer. If the symbol begins with
1824 a letter the statement is an assembly language @dfn{instruction}: it
1825 assembles into a machine language instruction.
1827 Different versions of @code{@value{AS}} for different computers
1828 recognize different instructions. In fact, the same symbol may
1829 represent a different instruction in a different computer's assembly
1833 @cindex @code{:} (label)
1834 @cindex label (@code{:})
1835 A label is a symbol immediately followed by a colon (@code{:}).
1836 Whitespace before a label or after a colon is permitted, but you may not
1837 have whitespace between a label's symbol and its colon. @xref{Labels}.
1840 For HPPA targets, labels need not be immediately followed by a colon, but
1841 the definition of a label must begin in column zero. This also implies that
1842 only one label may be defined on each line.
1846 label: .directive followed by something
1847 another_label: # This is an empty statement.
1848 instruction operand_1, operand_2, @dots{}
1855 A constant is a number, written so that its value is known by
1856 inspection, without knowing any context. Like this:
1859 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
1860 .ascii "Ring the bell\7" # A string constant.
1861 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
1862 .float 0f-314159265358979323846264338327\
1863 95028841971.693993751E-40 # - pi, a flonum.
1868 * Characters:: Character Constants
1869 * Numbers:: Number Constants
1873 @subsection Character Constants
1875 @cindex character constants
1876 @cindex constants, character
1877 There are two kinds of character constants. A @dfn{character} stands
1878 for one character in one byte and its value may be used in
1879 numeric expressions. String constants (properly called string
1880 @emph{literals}) are potentially many bytes and their values may not be
1881 used in arithmetic expressions.
1885 * Chars:: Characters
1889 @subsubsection Strings
1891 @cindex string constants
1892 @cindex constants, string
1893 A @dfn{string} is written between double-quotes. It may contain
1894 double-quotes or null characters. The way to get special characters
1895 into a string is to @dfn{escape} these characters: precede them with
1896 a backslash @samp{\} character. For example @samp{\\} represents
1897 one backslash: the first @code{\} is an escape which tells
1898 @code{@value{AS}} to interpret the second character literally as a backslash
1899 (which prevents @code{@value{AS}} from recognizing the second @code{\} as an
1900 escape character). The complete list of escapes follows.
1902 @cindex escape codes, character
1903 @cindex character escape codes
1906 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
1908 @cindex @code{\b} (backspace character)
1909 @cindex backspace (@code{\b})
1911 Mnemonic for backspace; for ASCII this is octal code 010.
1914 @c Mnemonic for EOText; for ASCII this is octal code 004.
1916 @cindex @code{\f} (formfeed character)
1917 @cindex formfeed (@code{\f})
1919 Mnemonic for FormFeed; for ASCII this is octal code 014.
1921 @cindex @code{\n} (newline character)
1922 @cindex newline (@code{\n})
1924 Mnemonic for newline; for ASCII this is octal code 012.
1927 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
1929 @cindex @code{\r} (carriage return character)
1930 @cindex carriage return (@code{\r})
1932 Mnemonic for carriage-Return; for ASCII this is octal code 015.
1935 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
1936 @c other assemblers.
1938 @cindex @code{\t} (tab)
1939 @cindex tab (@code{\t})
1941 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
1944 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
1945 @c @item \x @var{digit} @var{digit} @var{digit}
1946 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
1948 @cindex @code{\@var{ddd}} (octal character code)
1949 @cindex octal character code (@code{\@var{ddd}})
1950 @item \ @var{digit} @var{digit} @var{digit}
1951 An octal character code. The numeric code is 3 octal digits.
1952 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
1953 for example, @code{\008} has the value 010, and @code{\009} the value 011.
1955 @cindex @code{\@var{xd...}} (hex character code)
1956 @cindex hex character code (@code{\@var{xd...}})
1957 @item \@code{x} @var{hex-digits...}
1958 A hex character code. All trailing hex digits are combined. Either upper or
1959 lower case @code{x} works.
1961 @cindex @code{\\} (@samp{\} character)
1962 @cindex backslash (@code{\\})
1964 Represents one @samp{\} character.
1967 @c Represents one @samp{'} (accent acute) character.
1968 @c This is needed in single character literals
1969 @c (@xref{Characters,,Character Constants}.) to represent
1972 @cindex @code{\"} (doublequote character)
1973 @cindex doublequote (@code{\"})
1975 Represents one @samp{"} character. Needed in strings to represent
1976 this character, because an unescaped @samp{"} would end the string.
1978 @item \ @var{anything-else}
1979 Any other character when escaped by @kbd{\} gives a warning, but
1980 assembles as if the @samp{\} was not present. The idea is that if
1981 you used an escape sequence you clearly didn't want the literal
1982 interpretation of the following character. However @code{@value{AS}} has no
1983 other interpretation, so @code{@value{AS}} knows it is giving you the wrong
1984 code and warns you of the fact.
1987 Which characters are escapable, and what those escapes represent,
1988 varies widely among assemblers. The current set is what we think
1989 the BSD 4.2 assembler recognizes, and is a subset of what most C
1990 compilers recognize. If you are in doubt, do not use an escape
1994 @subsubsection Characters
1996 @cindex single character constant
1997 @cindex character, single
1998 @cindex constant, single character
1999 A single character may be written as a single quote immediately
2000 followed by that character. The same escapes apply to characters as
2001 to strings. So if you want to write the character backslash, you
2002 must write @kbd{'\\} where the first @code{\} escapes the second
2003 @code{\}. As you can see, the quote is an acute accent, not a
2004 grave accent. A newline
2006 @ifclear abnormal-separator
2007 (or semicolon @samp{;})
2009 @ifset abnormal-separator
2011 (or at sign @samp{@@})
2014 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2020 immediately following an acute accent is taken as a literal character
2021 and does not count as the end of a statement. The value of a character
2022 constant in a numeric expression is the machine's byte-wide code for
2023 that character. @code{@value{AS}} assumes your character code is ASCII:
2024 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2027 @subsection Number Constants
2029 @cindex constants, number
2030 @cindex number constants
2031 @code{@value{AS}} distinguishes three kinds of numbers according to how they
2032 are stored in the target machine. @emph{Integers} are numbers that
2033 would fit into an @code{int} in the C language. @emph{Bignums} are
2034 integers, but they are stored in more than 32 bits. @emph{Flonums}
2035 are floating point numbers, described below.
2038 * Integers:: Integers
2043 * Bit Fields:: Bit Fields
2049 @subsubsection Integers
2051 @cindex constants, integer
2053 @cindex binary integers
2054 @cindex integers, binary
2055 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2056 the binary digits @samp{01}.
2058 @cindex octal integers
2059 @cindex integers, octal
2060 An octal integer is @samp{0} followed by zero or more of the octal
2061 digits (@samp{01234567}).
2063 @cindex decimal integers
2064 @cindex integers, decimal
2065 A decimal integer starts with a non-zero digit followed by zero or
2066 more digits (@samp{0123456789}).
2068 @cindex hexadecimal integers
2069 @cindex integers, hexadecimal
2070 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2071 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2073 Integers have the usual values. To denote a negative integer, use
2074 the prefix operator @samp{-} discussed under expressions
2075 (@pxref{Prefix Ops,,Prefix Operators}).
2078 @subsubsection Bignums
2081 @cindex constants, bignum
2082 A @dfn{bignum} has the same syntax and semantics as an integer
2083 except that the number (or its negative) takes more than 32 bits to
2084 represent in binary. The distinction is made because in some places
2085 integers are permitted while bignums are not.
2088 @subsubsection Flonums
2090 @cindex floating point numbers
2091 @cindex constants, floating point
2093 @cindex precision, floating point
2094 A @dfn{flonum} represents a floating point number. The translation is
2095 indirect: a decimal floating point number from the text is converted by
2096 @code{@value{AS}} to a generic binary floating point number of more than
2097 sufficient precision. This generic floating point number is converted
2098 to a particular computer's floating point format (or formats) by a
2099 portion of @code{@value{AS}} specialized to that computer.
2101 A flonum is written by writing (in order)
2106 (@samp{0} is optional on the HPPA.)
2110 A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
2112 @kbd{e} is recommended. Case is not important.
2114 @c FIXME: verify if flonum syntax really this vague for most cases
2115 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2116 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2119 On the H8/300, H8/500,
2121 and AMD 29K architectures, the letter must be
2122 one of the letters @samp{DFPRSX} (in upper or lower case).
2124 On the ARC, the letter must be one of the letters @samp{DFRS}
2125 (in upper or lower case).
2127 On the Intel 960 architecture, the letter must be
2128 one of the letters @samp{DFT} (in upper or lower case).
2130 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2134 One of the letters @samp{DFPRSX} (in upper or lower case).
2137 One of the letters @samp{DFRS} (in upper or lower case).
2140 One of the letters @samp{DFPRSX} (in upper or lower case).
2143 The letter @samp{E} (upper case only).
2146 One of the letters @samp{DFT} (in upper or lower case).
2151 An optional sign: either @samp{+} or @samp{-}.
2154 An optional @dfn{integer part}: zero or more decimal digits.
2157 An optional @dfn{fractional part}: @samp{.} followed by zero
2158 or more decimal digits.
2161 An optional exponent, consisting of:
2165 An @samp{E} or @samp{e}.
2166 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2167 @c principle this can perfectly well be different on different targets.
2169 Optional sign: either @samp{+} or @samp{-}.
2171 One or more decimal digits.
2176 At least one of the integer part or the fractional part must be
2177 present. The floating point number has the usual base-10 value.
2179 @code{@value{AS}} does all processing using integers. Flonums are computed
2180 independently of any floating point hardware in the computer running
2185 @c Bit fields are written as a general facility but are also controlled
2186 @c by a conditional-compilation flag---which is as of now (21mar91)
2187 @c turned on only by the i960 config of GAS.
2189 @subsubsection Bit Fields
2192 @cindex constants, bit field
2193 You can also define numeric constants as @dfn{bit fields}.
2194 specify two numbers separated by a colon---
2196 @var{mask}:@var{value}
2199 @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2202 The resulting number is then packed
2204 @c this conditional paren in case bit fields turned on elsewhere than 960
2205 (in host-dependent byte order)
2207 into a field whose width depends on which assembler directive has the
2208 bit-field as its argument. Overflow (a result from the bitwise and
2209 requiring more binary digits to represent) is not an error; instead,
2210 more constants are generated, of the specified width, beginning with the
2211 least significant digits.@refill
2213 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2214 @code{.short}, and @code{.word} accept bit-field arguments.
2219 @chapter Sections and Relocation
2224 * Secs Background:: Background
2225 * Ld Sections:: Linker Sections
2226 * As Sections:: Assembler Internal Sections
2227 * Sub-Sections:: Sub-Sections
2231 @node Secs Background
2234 Roughly, a section is a range of addresses, with no gaps; all data
2235 ``in'' those addresses is treated the same for some particular purpose.
2236 For example there may be a ``read only'' section.
2238 @cindex linker, and assembler
2239 @cindex assembler, and linker
2240 The linker @code{@value{LD}} reads many object files (partial programs) and
2241 combines their contents to form a runnable program. When @code{@value{AS}}
2242 emits an object file, the partial program is assumed to start at address 0.
2243 @code{@value{LD}} assigns the final addresses for the partial program, so that
2244 different partial programs do not overlap. This is actually an
2245 oversimplification, but it suffices to explain how @code{@value{AS}} uses
2248 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2249 addresses. These blocks slide to their run-time addresses as rigid
2250 units; their length does not change and neither does the order of bytes
2251 within them. Such a rigid unit is called a @emph{section}. Assigning
2252 run-time addresses to sections is called @dfn{relocation}. It includes
2253 the task of adjusting mentions of object-file addresses so they refer to
2254 the proper run-time addresses.
2256 For the H8/300 and H8/500,
2257 and for the Hitachi SH,
2258 @code{@value{AS}} pads sections if needed to
2259 ensure they end on a word (sixteen bit) boundary.
2262 @cindex standard assembler sections
2263 An object file written by @code{@value{AS}} has at least three sections, any
2264 of which may be empty. These are named @dfn{text}, @dfn{data} and
2269 When it generates COFF output,
2271 @code{@value{AS}} can also generate whatever other named sections you specify
2272 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2273 If you do not use any directives that place output in the @samp{.text}
2274 or @samp{.data} sections, these sections still exist, but are empty.
2279 When @code{@value{AS}} generates SOM or ELF output for the HPPA,
2281 @code{@value{AS}} can also generate whatever other named sections you
2282 specify using the @samp{.space} and @samp{.subspace} directives. See
2283 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2284 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2285 assembler directives.
2288 Additionally, @code{@value{AS}} uses different names for the standard
2289 text, data, and bss sections when generating SOM output. Program text
2290 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2291 BSS into @samp{$BSS$}.
2295 Within the object file, the text section starts at address @code{0}, the
2296 data section follows, and the bss section follows the data section.
2299 When generating either SOM or ELF output files on the HPPA, the text
2300 section starts at address @code{0}, the data section at address
2301 @code{0x4000000}, and the bss section follows the data section.
2304 To let @code{@value{LD}} know which data changes when the sections are
2305 relocated, and how to change that data, @code{@value{AS}} also writes to the
2306 object file details of the relocation needed. To perform relocation
2307 @code{@value{LD}} must know, each time an address in the object
2311 Where in the object file is the beginning of this reference to
2314 How long (in bytes) is this reference?
2316 Which section does the address refer to? What is the numeric value of
2318 (@var{address}) @minus{} (@var{start-address of section})?
2321 Is the reference to an address ``Program-Counter relative''?
2324 @cindex addresses, format of
2325 @cindex section-relative addressing
2326 In fact, every address @code{@value{AS}} ever uses is expressed as
2328 (@var{section}) + (@var{offset into section})
2331 Further, most expressions @code{@value{AS}} computes have this section-relative
2334 (For some object formats, such as SOM for the HPPA, some expressions are
2335 symbol-relative instead.)
2338 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2339 @var{N} into section @var{secname}.''
2341 Apart from text, data and bss sections you need to know about the
2342 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2343 addresses in the absolute section remain unchanged. For example, address
2344 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2345 @code{@value{LD}}. Although the linker never arranges two partial programs'
2346 data sections with overlapping addresses after linking, @emph{by definition}
2347 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2348 part of a program is always the same address when the program is running as
2349 address @code{@{absolute@ 239@}} in any other part of the program.
2351 The idea of sections is extended to the @dfn{undefined} section. Any
2352 address whose section is unknown at assembly time is by definition
2353 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2354 Since numbers are always defined, the only way to generate an undefined
2355 address is to mention an undefined symbol. A reference to a named
2356 common block would be such a symbol: its value is unknown at assembly
2357 time so it has section @emph{undefined}.
2359 By analogy the word @emph{section} is used to describe groups of sections in
2360 the linked program. @code{@value{LD}} puts all partial programs' text
2361 sections in contiguous addresses in the linked program. It is
2362 customary to refer to the @emph{text section} of a program, meaning all
2363 the addresses of all partial programs' text sections. Likewise for
2364 data and bss sections.
2366 Some sections are manipulated by @code{@value{LD}}; others are invented for
2367 use of @code{@value{AS}} and have no meaning except during assembly.
2370 @section Linker Sections
2371 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2376 @cindex named sections
2377 @cindex sections, named
2378 @item named sections
2381 @cindex text section
2382 @cindex data section
2386 These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
2387 separate but equal sections. Anything you can say of one section is
2390 When the program is running, however, it is
2391 customary for the text section to be unalterable. The
2392 text section is often shared among processes: it contains
2393 instructions, constants and the like. The data section of a running
2394 program is usually alterable: for example, C variables would be stored
2395 in the data section.
2400 This section contains zeroed bytes when your program begins running. It
2401 is used to hold unitialized variables or common storage. The length of
2402 each partial program's bss section is important, but because it starts
2403 out containing zeroed bytes there is no need to store explicit zero
2404 bytes in the object file. The bss section was invented to eliminate
2405 those explicit zeros from object files.
2407 @cindex absolute section
2408 @item absolute section
2409 Address 0 of this section is always ``relocated'' to runtime address 0.
2410 This is useful if you want to refer to an address that @code{@value{LD}} must
2411 not change when relocating. In this sense we speak of absolute
2412 addresses being ``unrelocatable'': they do not change during relocation.
2414 @cindex undefined section
2415 @item undefined section
2416 This ``section'' is a catch-all for address references to objects not in
2417 the preceding sections.
2418 @c FIXME: ref to some other doc on obj-file formats could go here.
2421 @cindex relocation example
2422 An idealized example of three relocatable sections follows.
2424 The example uses the traditional section names @samp{.text} and @samp{.data}.
2426 Memory addresses are on the horizontal axis.
2430 @c END TEXI2ROFF-KILL
2433 partial program # 1: |ttttt|dddd|00|
2440 partial program # 2: |TTT|DDD|000|
2443 +--+---+-----+--+----+---+-----+~~
2444 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2445 +--+---+-----+--+----+---+-----+~~
2447 addresses: 0 @dots{}
2454 \line{\it Partial program \#1: \hfil}
2455 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2456 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2458 \line{\it Partial program \#2: \hfil}
2459 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2460 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2462 \line{\it linked program: \hfil}
2463 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2464 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2465 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2466 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2468 \line{\it addresses: \hfil}
2472 @c END TEXI2ROFF-KILL
2475 @section Assembler Internal Sections
2477 @cindex internal assembler sections
2478 @cindex sections in messages, internal
2479 These sections are meant only for the internal use of @code{@value{AS}}. They
2480 have no meaning at run-time. You do not really need to know about these
2481 sections for most purposes; but they can be mentioned in @code{@value{AS}}
2482 warning messages, so it might be helpful to have an idea of their
2483 meanings to @code{@value{AS}}. These sections are used to permit the
2484 value of every expression in your assembly language program to be a
2485 section-relative address.
2488 @cindex assembler internal logic error
2489 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2490 An internal assembler logic error has been found. This means there is a
2491 bug in the assembler.
2493 @cindex expr (internal section)
2495 The assembler stores complex expression internally as combinations of
2496 symbols. When it needs to represent an expression as a symbol, it puts
2497 it in the expr section.
2499 @c FIXME item transfer[t] vector preload
2500 @c FIXME item transfer[t] vector postload
2501 @c FIXME item register
2505 @section Sub-Sections
2507 @cindex numbered subsections
2508 @cindex grouping data
2514 fall into two sections: text and data.
2516 You may have separate groups of
2518 data in named sections
2522 data in named sections
2528 that you want to end up near to each other in the object file, even though they
2529 are not contiguous in the assembler source. @code{@value{AS}} allows you to
2530 use @dfn{subsections} for this purpose. Within each section, there can be
2531 numbered subsections with values from 0 to 8192. Objects assembled into the
2532 same subsection go into the object file together with other objects in the same
2533 subsection. For example, a compiler might want to store constants in the text
2534 section, but might not want to have them interspersed with the program being
2535 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2536 section of code being output, and a @samp{.text 1} before each group of
2537 constants being output.
2539 Subsections are optional. If you do not use subsections, everything
2540 goes in subsection number zero.
2543 Each subsection is zero-padded up to a multiple of four bytes.
2544 (Subsections may be padded a different amount on different flavors
2545 of @code{@value{AS}}.)
2549 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2550 boundary (two bytes).
2551 The same is true on the Hitachi SH.
2554 @c FIXME section padding (alignment)?
2555 @c Rich Pixley says padding here depends on target obj code format; that
2556 @c doesn't seem particularly useful to say without further elaboration,
2557 @c so for now I say nothing about it. If this is a generic BFD issue,
2558 @c these paragraphs might need to vanish from this manual, and be
2559 @c discussed in BFD chapter of binutils (or some such).
2562 On the AMD 29K family, no particular padding is added to section or
2563 subsection sizes; @value{AS} forces no alignment on this platform.
2567 Subsections appear in your object file in numeric order, lowest numbered
2568 to highest. (All this to be compatible with other people's assemblers.)
2569 The object file contains no representation of subsections; @code{@value{LD}} and
2570 other programs that manipulate object files see no trace of them.
2571 They just see all your text subsections as a text section, and all your
2572 data subsections as a data section.
2574 To specify which subsection you want subsequent statements assembled
2575 into, use a numeric argument to specify it, in a @samp{.text
2576 @var{expression}} or a @samp{.data @var{expression}} statement.
2579 When generating COFF output, you
2584 can also use an extra subsection
2585 argument with arbitrary named sections: @samp{.section @var{name},
2588 @var{Expression} should be an absolute expression.
2589 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2590 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2591 begins in @code{text 0}. For instance:
2593 .text 0 # The default subsection is text 0 anyway.
2594 .ascii "This lives in the first text subsection. *"
2596 .ascii "But this lives in the second text subsection."
2598 .ascii "This lives in the data section,"
2599 .ascii "in the first data subsection."
2601 .ascii "This lives in the first text section,"
2602 .ascii "immediately following the asterisk (*)."
2605 Each section has a @dfn{location counter} incremented by one for every byte
2606 assembled into that section. Because subsections are merely a convenience
2607 restricted to @code{@value{AS}} there is no concept of a subsection location
2608 counter. There is no way to directly manipulate a location counter---but the
2609 @code{.align} directive changes it, and any label definition captures its
2610 current value. The location counter of the section where statements are being
2611 assembled is said to be the @dfn{active} location counter.
2614 @section bss Section
2617 @cindex common variable storage
2618 The bss section is used for local common variable storage.
2619 You may allocate address space in the bss section, but you may
2620 not dictate data to load into it before your program executes. When
2621 your program starts running, all the contents of the bss
2622 section are zeroed bytes.
2624 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2625 @ref{Lcomm,,@code{.lcomm}}.
2627 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2628 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2631 When assembling for a target which supports multiple sections, such as ELF or
2632 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2633 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2634 section. Typically the section will only contain symbol definitions and
2635 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2642 Symbols are a central concept: the programmer uses symbols to name
2643 things, the linker uses symbols to link, and the debugger uses symbols
2647 @cindex debuggers, and symbol order
2648 @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
2649 the same order they were declared. This may break some debuggers.
2654 * Setting Symbols:: Giving Symbols Other Values
2655 * Symbol Names:: Symbol Names
2656 * Dot:: The Special Dot Symbol
2657 * Symbol Attributes:: Symbol Attributes
2664 A @dfn{label} is written as a symbol immediately followed by a colon
2665 @samp{:}. The symbol then represents the current value of the
2666 active location counter, and is, for example, a suitable instruction
2667 operand. You are warned if you use the same symbol to represent two
2668 different locations: the first definition overrides any other
2672 On the HPPA, the usual form for a label need not be immediately followed by a
2673 colon, but instead must start in column zero. Only one label may be defined on
2674 a single line. To work around this, the HPPA version of @code{@value{AS}} also
2675 provides a special directive @code{.label} for defining labels more flexibly.
2678 @node Setting Symbols
2679 @section Giving Symbols Other Values
2681 @cindex assigning values to symbols
2682 @cindex symbol values, assigning
2683 A symbol can be given an arbitrary value by writing a symbol, followed
2684 by an equals sign @samp{=}, followed by an expression
2685 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2686 directive. @xref{Set,,@code{.set}}.
2689 @section Symbol Names
2691 @cindex symbol names
2692 @cindex names, symbol
2693 @ifclear SPECIAL-SYMS
2694 Symbol names begin with a letter or with one of @samp{._}. On most
2695 machines, you can also use @code{$} in symbol names; exceptions are
2696 noted in @ref{Machine Dependencies}. That character may be followed by any
2697 string of digits, letters, dollar signs (unless otherwise noted in
2698 @ref{Machine Dependencies}), and underscores.
2701 For the AMD 29K family, @samp{?} is also allowed in the
2702 body of a symbol name, though not at its beginning.
2707 Symbol names begin with a letter or with one of @samp{._}. On the
2709 H8/500, you can also use @code{$} in symbol names. That character may
2710 be followed by any string of digits, letters, dollar signs (save on the
2711 H8/300), and underscores.
2715 Case of letters is significant: @code{foo} is a different symbol name
2718 Each symbol has exactly one name. Each name in an assembly language program
2719 refers to exactly one symbol. You may use that symbol name any number of times
2722 @subheading Local Symbol Names
2724 @cindex local symbol names
2725 @cindex symbol names, local
2726 @cindex temporary symbol names
2727 @cindex symbol names, temporary
2728 Local symbols help compilers and programmers use names temporarily.
2729 There are ten local symbol names, which are re-used throughout the
2730 program. You may refer to them using the names @samp{0} @samp{1}
2731 @dots{} @samp{9}. To define a local symbol, write a label of the form
2732 @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
2733 recent previous definition of that symbol write @samp{@b{N}b}, using the
2734 same digit as when you defined the label. To refer to the next
2735 definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
2736 a choice of 10 forward references. The @samp{b} stands for
2737 ``backwards'' and the @samp{f} stands for ``forwards''.
2739 Local symbols are not emitted by the current @sc{gnu} C compiler.
2741 There is no restriction on how you can use these labels, but
2742 remember that at any point in the assembly you can refer to at most
2743 10 prior local labels and to at most 10 forward local labels.
2745 Local symbol names are only a notation device. They are immediately
2746 transformed into more conventional symbol names before the assembler
2747 uses them. The symbol names stored in the symbol table, appearing in
2748 error messages and optionally emitted to the object file have these
2753 All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
2754 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
2755 used for symbols you are never intended to see. If you use the
2756 @samp{-L} option then @code{@value{AS}} retains these symbols in the
2757 object file. If you also instruct @code{@value{LD}} to retain these symbols,
2758 you may use them in debugging.
2761 If the label is written @samp{0:} then the digit is @samp{0}.
2762 If the label is written @samp{1:} then the digit is @samp{1}.
2763 And so on up through @samp{9:}.
2766 This unusual character is included so you do not accidentally invent
2767 a symbol of the same name. The character has ASCII value
2770 @item @emph{ordinal number}
2771 This is a serial number to keep the labels distinct. The first
2772 @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
2773 number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
2777 For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th
2778 @code{3:} is named @code{L3@kbd{C-A}44}.
2781 @section The Special Dot Symbol
2783 @cindex dot (symbol)
2784 @cindex @code{.} (symbol)
2785 @cindex current address
2786 @cindex location counter
2787 The special symbol @samp{.} refers to the current address that
2788 @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
2789 .long .} defines @code{melvin} to contain its own address.
2790 Assigning a value to @code{.} is treated the same as a @code{.org}
2791 directive. Thus, the expression @samp{.=.+4} is the same as saying
2792 @ifclear no-space-dir
2801 @node Symbol Attributes
2802 @section Symbol Attributes
2804 @cindex symbol attributes
2805 @cindex attributes, symbol
2806 Every symbol has, as well as its name, the attributes ``Value'' and
2807 ``Type''. Depending on output format, symbols can also have auxiliary
2810 The detailed definitions are in @file{a.out.h}.
2813 If you use a symbol without defining it, @code{@value{AS}} assumes zero for
2814 all these attributes, and probably won't warn you. This makes the
2815 symbol an externally defined symbol, which is generally what you
2819 * Symbol Value:: Value
2820 * Symbol Type:: Type
2823 * a.out Symbols:: Symbol Attributes: @code{a.out}
2827 * a.out Symbols:: Symbol Attributes: @code{a.out}
2830 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
2835 * COFF Symbols:: Symbol Attributes for COFF
2838 * SOM Symbols:: Symbol Attributes for SOM
2845 @cindex value of a symbol
2846 @cindex symbol value
2847 The value of a symbol is (usually) 32 bits. For a symbol which labels a
2848 location in the text, data, bss or absolute sections the value is the
2849 number of addresses from the start of that section to the label.
2850 Naturally for text, data and bss sections the value of a symbol changes
2851 as @code{@value{LD}} changes section base addresses during linking. Absolute
2852 symbols' values do not change during linking: that is why they are
2855 The value of an undefined symbol is treated in a special way. If it is
2856 0 then the symbol is not defined in this assembler source file, and
2857 @code{@value{LD}} tries to determine its value from other files linked into the
2858 same program. You make this kind of symbol simply by mentioning a symbol
2859 name without defining it. A non-zero value represents a @code{.comm}
2860 common declaration. The value is how much common storage to reserve, in
2861 bytes (addresses). The symbol refers to the first address of the
2867 @cindex type of a symbol
2869 The type attribute of a symbol contains relocation (section)
2870 information, any flag settings indicating that a symbol is external, and
2871 (optionally), other information for linkers and debuggers. The exact
2872 format depends on the object-code output format in use.
2877 @c The following avoids a "widow" subsection title. @group would be
2878 @c better if it were available outside examples.
2881 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
2883 @cindex @code{b.out} symbol attributes
2884 @cindex symbol attributes, @code{b.out}
2885 These symbol attributes appear only when @code{@value{AS}} is configured for
2886 one of the Berkeley-descended object output formats---@code{a.out} or
2892 @subsection Symbol Attributes: @code{a.out}
2894 @cindex @code{a.out} symbol attributes
2895 @cindex symbol attributes, @code{a.out}
2901 @subsection Symbol Attributes: @code{a.out}
2903 @cindex @code{a.out} symbol attributes
2904 @cindex symbol attributes, @code{a.out}
2908 * Symbol Desc:: Descriptor
2909 * Symbol Other:: Other
2913 @subsubsection Descriptor
2915 @cindex descriptor, of @code{a.out} symbol
2916 This is an arbitrary 16-bit value. You may establish a symbol's
2917 descriptor value by using a @code{.desc} statement
2918 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
2922 @subsubsection Other
2924 @cindex other attribute, of @code{a.out} symbol
2925 This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
2930 @subsection Symbol Attributes for COFF
2932 @cindex COFF symbol attributes
2933 @cindex symbol attributes, COFF
2935 The COFF format supports a multitude of auxiliary symbol attributes;
2936 like the primary symbol attributes, they are set between @code{.def} and
2937 @code{.endef} directives.
2939 @subsubsection Primary Attributes
2941 @cindex primary attributes, COFF symbols
2942 The symbol name is set with @code{.def}; the value and type,
2943 respectively, with @code{.val} and @code{.type}.
2945 @subsubsection Auxiliary Attributes
2947 @cindex auxiliary attributes, COFF symbols
2948 The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
2949 @code{.size}, and @code{.tag} can generate auxiliary symbol table
2950 information for COFF.
2955 @subsection Symbol Attributes for SOM
2957 @cindex SOM symbol attributes
2958 @cindex symbol attributes, SOM
2960 The SOM format for the HPPA supports a multitude of symbol attributes set with
2961 the @code{.EXPORT} and @code{.IMPORT} directives.
2963 The attributes are described in @cite{HP9000 Series 800 Assembly
2964 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
2965 @code{EXPORT} assembler directive documentation.
2969 @chapter Expressions
2973 @cindex numeric values
2974 An @dfn{expression} specifies an address or numeric value.
2975 Whitespace may precede and/or follow an expression.
2977 The result of an expression must be an absolute number, or else an offset into
2978 a particular section. If an expression is not absolute, and there is not
2979 enough information when @code{@value{AS}} sees the expression to know its
2980 section, a second pass over the source program might be necessary to interpret
2981 the expression---but the second pass is currently not implemented.
2982 @code{@value{AS}} aborts with an error message in this situation.
2985 * Empty Exprs:: Empty Expressions
2986 * Integer Exprs:: Integer Expressions
2990 @section Empty Expressions
2992 @cindex empty expressions
2993 @cindex expressions, empty
2994 An empty expression has no value: it is just whitespace or null.
2995 Wherever an absolute expression is required, you may omit the
2996 expression, and @code{@value{AS}} assumes a value of (absolute) 0. This
2997 is compatible with other assemblers.
3000 @section Integer Expressions
3002 @cindex integer expressions
3003 @cindex expressions, integer
3004 An @dfn{integer expression} is one or more @emph{arguments} delimited
3005 by @emph{operators}.
3008 * Arguments:: Arguments
3009 * Operators:: Operators
3010 * Prefix Ops:: Prefix Operators
3011 * Infix Ops:: Infix Operators
3015 @subsection Arguments
3017 @cindex expression arguments
3018 @cindex arguments in expressions
3019 @cindex operands in expressions
3020 @cindex arithmetic operands
3021 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3022 contexts arguments are sometimes called ``arithmetic operands''. In
3023 this manual, to avoid confusing them with the ``instruction operands'' of
3024 the machine language, we use the term ``argument'' to refer to parts of
3025 expressions only, reserving the word ``operand'' to refer only to machine
3026 instruction operands.
3028 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3029 @var{section} is one of text, data, bss, absolute,
3030 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3033 Numbers are usually integers.
3035 A number can be a flonum or bignum. In this case, you are warned
3036 that only the low order 32 bits are used, and @code{@value{AS}} pretends
3037 these 32 bits are an integer. You may write integer-manipulating
3038 instructions that act on exotic constants, compatible with other
3041 @cindex subexpressions
3042 Subexpressions are a left parenthesis @samp{(} followed by an integer
3043 expression, followed by a right parenthesis @samp{)}; or a prefix
3044 operator followed by an argument.
3047 @subsection Operators
3049 @cindex operators, in expressions
3050 @cindex arithmetic functions
3051 @cindex functions, in expressions
3052 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3053 operators are followed by an argument. Infix operators appear
3054 between their arguments. Operators may be preceded and/or followed by
3058 @subsection Prefix Operator
3060 @cindex prefix operators
3061 @code{@value{AS}} has the following @dfn{prefix operators}. They each take
3062 one argument, which must be absolute.
3064 @c the tex/end tex stuff surrounding this small table is meant to make
3065 @c it align, on the printed page, with the similar table in the next
3066 @c section (which is inside an enumerate).
3068 \global\advance\leftskip by \itemindent
3073 @dfn{Negation}. Two's complement negation.
3075 @dfn{Complementation}. Bitwise not.
3079 \global\advance\leftskip by -\itemindent
3083 @subsection Infix Operators
3085 @cindex infix operators
3086 @cindex operators, permitted arguments
3087 @dfn{Infix operators} take two arguments, one on either side. Operators
3088 have precedence, but operations with equal precedence are performed left
3089 to right. Apart from @code{+} or @code{-}, both arguments must be
3090 absolute, and the result is absolute.
3093 @cindex operator precedence
3094 @cindex precedence of operators
3101 @dfn{Multiplication}.
3104 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3111 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3115 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3119 Intermediate precedence
3124 @dfn{Bitwise Inclusive Or}.
3130 @dfn{Bitwise Exclusive Or}.
3133 @dfn{Bitwise Or Not}.
3140 @cindex addition, permitted arguments
3141 @cindex plus, permitted arguments
3142 @cindex arguments for addition
3144 @dfn{Addition}. If either argument is absolute, the result has the section of
3145 the other argument. You may not add together arguments from different
3148 @cindex subtraction, permitted arguments
3149 @cindex minus, permitted arguments
3150 @cindex arguments for subtraction
3152 @dfn{Subtraction}. If the right argument is absolute, the
3153 result has the section of the left argument.
3154 If both arguments are in the same section, the result is absolute.
3155 You may not subtract arguments from different sections.
3156 @c FIXME is there still something useful to say about undefined - undefined ?
3160 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3161 address; you can only have a defined section in one of the two arguments.
3164 @chapter Assembler Directives
3166 @cindex directives, machine independent
3167 @cindex pseudo-ops, machine independent
3168 @cindex machine independent directives
3169 All assembler directives have names that begin with a period (@samp{.}).
3170 The rest of the name is letters, usually in lower case.
3172 This chapter discusses directives that are available regardless of the
3173 target machine configuration for the @sc{gnu} assembler.
3175 Some machine configurations provide additional directives.
3176 @xref{Machine Dependencies}.
3179 @ifset machine-directives
3180 @xref{Machine Dependencies} for additional directives.
3185 * Abort:: @code{.abort}
3187 * ABORT:: @code{.ABORT}
3190 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3191 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3192 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3193 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3194 * Byte:: @code{.byte @var{expressions}}
3195 * Comm:: @code{.comm @var{symbol} , @var{length} }
3196 * Data:: @code{.data @var{subsection}}
3198 * Def:: @code{.def @var{name}}
3201 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3207 * Double:: @code{.double @var{flonums}}
3208 * Eject:: @code{.eject}
3209 * Else:: @code{.else}
3210 * Elseif:: @code{.elseif}
3213 * Endef:: @code{.endef}
3216 * Endfunc:: @code{.endfunc}
3217 * Endif:: @code{.endif}
3218 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3219 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3221 * Exitm:: @code{.exitm}
3222 * Extern:: @code{.extern}
3223 * Fail:: @code{.fail}
3224 @ifclear no-file-dir
3225 * File:: @code{.file @var{string}}
3228 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3229 * Float:: @code{.float @var{flonums}}
3230 * Func:: @code{.func}
3231 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3233 * Hidden:: @code{.hidden @var{names}}
3236 * hword:: @code{.hword @var{expressions}}
3237 * Ident:: @code{.ident}
3238 * If:: @code{.if @var{absolute expression}}
3239 * Include:: @code{.include "@var{file}"}
3240 * Int:: @code{.int @var{expressions}}
3242 * Internal:: @code{.internal @var{names}}
3245 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3246 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3247 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3248 * Lflags:: @code{.lflags}
3249 @ifclear no-line-dir
3250 * Line:: @code{.line @var{line-number}}
3253 * Ln:: @code{.ln @var{line-number}}
3254 * Linkonce:: @code{.linkonce [@var{type}]}
3255 * List:: @code{.list}
3256 * Long:: @code{.long @var{expressions}}
3258 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3261 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3262 * MRI:: @code{.mri @var{val}}
3263 * Nolist:: @code{.nolist}
3264 * Octa:: @code{.octa @var{bignums}}
3265 * Org:: @code{.org @var{new-lc} , @var{fill}}
3266 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3268 * PopSection:: @code{.popsection}
3269 * Previous:: @code{.previous}
3272 * Print:: @code{.print @var{string}}
3274 * Protected:: @code{.protected @var{names}}
3277 * Psize:: @code{.psize @var{lines}, @var{columns}}
3278 * Purgem:: @code{.purgem @var{name}}
3280 * PushSection:: @code{.pushsection @var{name}}
3283 * Quad:: @code{.quad @var{bignums}}
3284 * Rept:: @code{.rept @var{count}}
3285 * Sbttl:: @code{.sbttl "@var{subheading}"}
3287 * Scl:: @code{.scl @var{class}}
3288 * Section:: @code{.section @var{name}, @var{subsection}}
3291 * Set:: @code{.set @var{symbol}, @var{expression}}
3292 * Short:: @code{.short @var{expressions}}
3293 * Single:: @code{.single @var{flonums}}
3294 * Size:: @code{.size [@var{name} , @var{expression}]}
3295 * Skip:: @code{.skip @var{size} , @var{fill}}
3296 * Sleb128:: @code{.sleb128 @var{expressions}}
3297 * Space:: @code{.space @var{size} , @var{fill}}
3299 * Stab:: @code{.stabd, .stabn, .stabs}
3302 * String:: @code{.string "@var{str}"}
3303 * Struct:: @code{.struct @var{expression}}
3305 * SubSection:: @code{.subsection}
3306 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3310 * Tag:: @code{.tag @var{structname}}
3313 * Text:: @code{.text @var{subsection}}
3314 * Title:: @code{.title "@var{heading}"}
3315 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3316 * Uleb128:: @code{.uleb128 @var{expressions}}
3318 * Val:: @code{.val @var{addr}}
3322 * Version:: @code{.version "@var{string}"}
3323 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3324 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3325 * Weak:: @code{.weak @var{names}}
3328 * Word:: @code{.word @var{expressions}}
3329 * Deprecated:: Deprecated Directives
3333 @section @code{.abort}
3335 @cindex @code{abort} directive
3336 @cindex stopping the assembly
3337 This directive stops the assembly immediately. It is for
3338 compatibility with other assemblers. The original idea was that the
3339 assembly language source would be piped into the assembler. If the sender
3340 of the source quit, it could use this directive tells @code{@value{AS}} to
3341 quit also. One day @code{.abort} will not be supported.
3345 @section @code{.ABORT}
3347 @cindex @code{ABORT} directive
3348 When producing COFF output, @code{@value{AS}} accepts this directive as a
3349 synonym for @samp{.abort}.
3352 When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
3358 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3360 @cindex padding the location counter
3361 @cindex @code{align} directive
3362 Pad the location counter (in the current subsection) to a particular storage
3363 boundary. The first expression (which must be absolute) is the alignment
3364 required, as described below.
3366 The second expression (also absolute) gives the fill value to be stored in the
3367 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3368 padding bytes are normally zero. However, on some systems, if the section is
3369 marked as containing code and the fill value is omitted, the space is filled
3370 with no-op instructions.
3372 The third expression is also absolute, and is also optional. If it is present,
3373 it is the maximum number of bytes that should be skipped by this alignment
3374 directive. If doing the alignment would require skipping more bytes than the
3375 specified maximum, then the alignment is not done at all. You can omit the
3376 fill value (the second argument) entirely by simply using two commas after the
3377 required alignment; this can be useful if you want the alignment to be filled
3378 with no-op instructions when appropriate.
3380 The way the required alignment is specified varies from system to system.
3381 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3383 the first expression is the
3384 alignment request in bytes. For example @samp{.align 8} advances
3385 the location counter until it is a multiple of 8. If the location counter
3386 is already a multiple of 8, no change is needed.
3388 For other systems, including the i386 using a.out format, and the arm and
3389 strongarm, it is the
3390 number of low-order zero bits the location counter must have after
3391 advancement. For example @samp{.align 3} advances the location
3392 counter until it a multiple of 8. If the location counter is already a
3393 multiple of 8, no change is needed.
3395 This inconsistency is due to the different behaviors of the various
3396 native assemblers for these systems which GAS must emulate.
3397 GAS also provides @code{.balign} and @code{.p2align} directives,
3398 described later, which have a consistent behavior across all
3399 architectures (but are specific to GAS).
3402 @section @code{.ascii "@var{string}"}@dots{}
3404 @cindex @code{ascii} directive
3405 @cindex string literals
3406 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3407 separated by commas. It assembles each string (with no automatic
3408 trailing zero byte) into consecutive addresses.
3411 @section @code{.asciz "@var{string}"}@dots{}
3413 @cindex @code{asciz} directive
3414 @cindex zero-terminated strings
3415 @cindex null-terminated strings
3416 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3417 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3420 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3422 @cindex padding the location counter given number of bytes
3423 @cindex @code{balign} directive
3424 Pad the location counter (in the current subsection) to a particular
3425 storage boundary. The first expression (which must be absolute) is the
3426 alignment request in bytes. For example @samp{.balign 8} advances
3427 the location counter until it is a multiple of 8. If the location counter
3428 is already a multiple of 8, no change is needed.
3430 The second expression (also absolute) gives the fill value to be stored in the
3431 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3432 padding bytes are normally zero. However, on some systems, if the section is
3433 marked as containing code and the fill value is omitted, the space is filled
3434 with no-op instructions.
3436 The third expression is also absolute, and is also optional. If it is present,
3437 it is the maximum number of bytes that should be skipped by this alignment
3438 directive. If doing the alignment would require skipping more bytes than the
3439 specified maximum, then the alignment is not done at all. You can omit the
3440 fill value (the second argument) entirely by simply using two commas after the
3441 required alignment; this can be useful if you want the alignment to be filled
3442 with no-op instructions when appropriate.
3444 @cindex @code{balignw} directive
3445 @cindex @code{balignl} directive
3446 The @code{.balignw} and @code{.balignl} directives are variants of the
3447 @code{.balign} directive. The @code{.balignw} directive treats the fill
3448 pattern as a two byte word value. The @code{.balignl} directives treats the
3449 fill pattern as a four byte longword value. For example, @code{.balignw
3450 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3451 filled in with the value 0x368d (the exact placement of the bytes depends upon
3452 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3456 @section @code{.byte @var{expressions}}
3458 @cindex @code{byte} directive
3459 @cindex integers, one byte
3460 @code{.byte} expects zero or more expressions, separated by commas.
3461 Each expression is assembled into the next byte.
3464 @section @code{.comm @var{symbol} , @var{length} }
3466 @cindex @code{comm} directive
3467 @cindex symbol, common
3468 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3469 common symbol in one object file may be merged with a defined or common symbol
3470 of the same name in another object file. If @code{@value{LD}} does not see a
3471 definition for the symbol--just one or more common symbols--then it will
3472 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3473 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3474 the same name, and they do not all have the same size, it will allocate space
3475 using the largest size.
3478 When using ELF, the @code{.comm} directive takes an optional third argument.
3479 This is the desired alignment of the symbol, specified as a byte boundary (for
3480 example, an alignment of 16 means that the least significant 4 bits of the
3481 address should be zero). The alignment must be an absolute expression, and it
3482 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3483 for the common symbol, it will use the alignment when placing the symbol. If
3484 no alignment is specified, @code{@value{AS}} will set the alignment to the
3485 largest power of two less than or equal to the size of the symbol, up to a
3490 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3491 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3495 @section @code{.data @var{subsection}}
3497 @cindex @code{data} directive
3498 @code{.data} tells @code{@value{AS}} to assemble the following statements onto the
3499 end of the data subsection numbered @var{subsection} (which is an
3500 absolute expression). If @var{subsection} is omitted, it defaults
3505 @section @code{.def @var{name}}
3507 @cindex @code{def} directive
3508 @cindex COFF symbols, debugging
3509 @cindex debugging COFF symbols
3510 Begin defining debugging information for a symbol @var{name}; the
3511 definition extends until the @code{.endef} directive is encountered.
3514 This directive is only observed when @code{@value{AS}} is configured for COFF
3515 format output; when producing @code{b.out}, @samp{.def} is recognized,
3522 @section @code{.desc @var{symbol}, @var{abs-expression}}
3524 @cindex @code{desc} directive
3525 @cindex COFF symbol descriptor
3526 @cindex symbol descriptor, COFF
3527 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3528 to the low 16 bits of an absolute expression.
3531 The @samp{.desc} directive is not available when @code{@value{AS}} is
3532 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3533 object format. For the sake of compatibility, @code{@value{AS}} accepts
3534 it, but produces no output, when configured for COFF.
3540 @section @code{.dim}
3542 @cindex @code{dim} directive
3543 @cindex COFF auxiliary symbol information
3544 @cindex auxiliary symbol information, COFF
3545 This directive is generated by compilers to include auxiliary debugging
3546 information in the symbol table. It is only permitted inside
3547 @code{.def}/@code{.endef} pairs.
3550 @samp{.dim} is only meaningful when generating COFF format output; when
3551 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
3557 @section @code{.double @var{flonums}}
3559 @cindex @code{double} directive
3560 @cindex floating point numbers (double)
3561 @code{.double} expects zero or more flonums, separated by commas. It
3562 assembles floating point numbers.
3564 The exact kind of floating point numbers emitted depends on how
3565 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
3569 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3570 in @sc{ieee} format.
3575 @section @code{.eject}
3577 @cindex @code{eject} directive
3578 @cindex new page, in listings
3579 @cindex page, in listings
3580 @cindex listing control: new page
3581 Force a page break at this point, when generating assembly listings.
3584 @section @code{.else}
3586 @cindex @code{else} directive
3587 @code{.else} is part of the @code{@value{AS}} support for conditional
3588 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3589 of code to be assembled if the condition for the preceding @code{.if}
3593 @section @code{.elseif}
3595 @cindex @code{elseif} directive
3596 @code{.elseif} is part of the @code{@value{AS}} support for conditional
3597 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3598 @code{.if} block that would otherwise fill the entire @code{.else} section.
3601 @section @code{.end}
3603 @cindex @code{end} directive
3604 @code{.end} marks the end of the assembly file. @code{@value{AS}} does not
3605 process anything in the file past the @code{.end} directive.
3609 @section @code{.endef}
3611 @cindex @code{endef} directive
3612 This directive flags the end of a symbol definition begun with
3616 @samp{.endef} is only meaningful when generating COFF format output; if
3617 @code{@value{AS}} is configured to generate @code{b.out}, it accepts this
3618 directive but ignores it.
3623 @section @code{.endfunc}
3624 @cindex @code{endfunc} directive
3625 @code{.endfunc} marks the end of a function specified with @code{.func}.
3628 @section @code{.endif}
3630 @cindex @code{endif} directive
3631 @code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
3632 it marks the end of a block of code that is only assembled
3633 conditionally. @xref{If,,@code{.if}}.
3636 @section @code{.equ @var{symbol}, @var{expression}}
3638 @cindex @code{equ} directive
3639 @cindex assigning values to symbols
3640 @cindex symbols, assigning values to
3641 This directive sets the value of @var{symbol} to @var{expression}.
3642 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3645 The syntax for @code{equ} on the HPPA is
3646 @samp{@var{symbol} .equ @var{expression}}.
3650 @section @code{.equiv @var{symbol}, @var{expression}}
3651 @cindex @code{equiv} directive
3652 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3653 the assembler will signal an error if @var{symbol} is already defined.
3655 Except for the contents of the error message, this is roughly equivalent to
3664 @section @code{.err}
3665 @cindex @code{err} directive
3666 If @code{@value{AS}} assembles a @code{.err} directive, it will print an error
3667 message and, unless the @code{-Z} option was used, it will not generate an
3668 object file. This can be used to signal error an conditionally compiled code.
3671 @section @code{.exitm}
3672 Exit early from the current macro definition. @xref{Macro}.
3675 @section @code{.extern}
3677 @cindex @code{extern} directive
3678 @code{.extern} is accepted in the source program---for compatibility
3679 with other assemblers---but it is ignored. @code{@value{AS}} treats
3680 all undefined symbols as external.
3683 @section @code{.fail @var{expression}}
3685 @cindex @code{fail} directive
3686 Generates an error or a warning. If the value of the @var{expression} is 500
3687 or more, @code{@value{AS}} will print a warning message. If the value is less
3688 than 500, @code{@value{AS}} will print an error message. The message will
3689 include the value of @var{expression}. This can occasionally be useful inside
3690 complex nested macros or conditional assembly.
3692 @ifclear no-file-dir
3694 @section @code{.file @var{string}}
3696 @cindex @code{file} directive
3697 @cindex logical file name
3698 @cindex file name, logical
3699 @code{.file} tells @code{@value{AS}} that we are about to start a new logical
3700 file. @var{string} is the new file name. In general, the filename is
3701 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
3702 to specify an empty file name, you must give the quotes--@code{""}. This
3703 statement may go away in future: it is only recognized to be compatible with
3704 old @code{@value{AS}} programs.
3706 In some configurations of @code{@value{AS}}, @code{.file} has already been
3707 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
3712 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
3714 @cindex @code{fill} directive
3715 @cindex writing patterns in memory
3716 @cindex patterns, writing in memory
3717 @var{result}, @var{size} and @var{value} are absolute expressions.
3718 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
3719 may be zero or more. @var{Size} may be zero or more, but if it is
3720 more than 8, then it is deemed to have the value 8, compatible with
3721 other people's assemblers. The contents of each @var{repeat} bytes
3722 is taken from an 8-byte number. The highest order 4 bytes are
3723 zero. The lowest order 4 bytes are @var{value} rendered in the
3724 byte-order of an integer on the computer @code{@value{AS}} is assembling for.
3725 Each @var{size} bytes in a repetition is taken from the lowest order
3726 @var{size} bytes of this number. Again, this bizarre behavior is
3727 compatible with other people's assemblers.
3729 @var{size} and @var{value} are optional.
3730 If the second comma and @var{value} are absent, @var{value} is
3731 assumed zero. If the first comma and following tokens are absent,
3732 @var{size} is assumed to be 1.
3735 @section @code{.float @var{flonums}}
3737 @cindex floating point numbers (single)
3738 @cindex @code{float} directive
3739 This directive assembles zero or more flonums, separated by commas. It
3740 has the same effect as @code{.single}.
3742 The exact kind of floating point numbers emitted depends on how
3743 @code{@value{AS}} is configured.
3744 @xref{Machine Dependencies}.
3748 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
3749 in @sc{ieee} format.
3754 @section @code{.func @var{name}[,@var{label}]}
3755 @cindex @code{func} directive
3756 @code{.func} emits debugging information to denote function @var{name}, and
3757 is ignored unless the file is assembled with debugging enabled.
3758 Only @samp{--gstabs} is currently supported.
3759 @var{label} is the entry point of the function and if omitted @var{name}
3760 prepended with the @samp{leading char} is used.
3761 @samp{leading char} is usually @code{_} or nothing, depending on the target.
3762 All functions are currently defined to have @code{void} return type.
3763 The function must be terminated with @code{.endfunc}.
3766 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3768 @cindex @code{global} directive
3769 @cindex symbol, making visible to linker
3770 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
3771 @var{symbol} in your partial program, its value is made available to
3772 other partial programs that are linked with it. Otherwise,
3773 @var{symbol} takes its attributes from a symbol of the same name
3774 from another file linked into the same program.
3776 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
3777 compatibility with other assemblers.
3780 On the HPPA, @code{.global} is not always enough to make it accessible to other
3781 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
3782 @xref{HPPA Directives,, HPPA Assembler Directives}.
3787 @section @code{.hidden @var{names}}
3789 @cindex @code{.hidden} directive
3791 This one of the ELF visibility directives. The other two are
3792 @pxref{Internal,,@code{.internal}} and @pxref{Protected,,@code{.protected}}
3794 This directive overrides the named symbols default visibility (which is set by
3795 their binding: local, global or weak). The directive sets the visibility to
3796 @code{hidden} which means that the symbols are not visible to other components.
3797 Such symbols are always considered to be @code{protected} as well.
3801 @section @code{.hword @var{expressions}}
3803 @cindex @code{hword} directive
3804 @cindex integers, 16-bit
3805 @cindex numbers, 16-bit
3806 @cindex sixteen bit integers
3807 This expects zero or more @var{expressions}, and emits
3808 a 16 bit number for each.
3811 This directive is a synonym for @samp{.short}; depending on the target
3812 architecture, it may also be a synonym for @samp{.word}.
3816 This directive is a synonym for @samp{.short}.
3819 This directive is a synonym for both @samp{.short} and @samp{.word}.
3824 @section @code{.ident}
3826 @cindex @code{ident} directive
3827 This directive is used by some assemblers to place tags in object files.
3828 @code{@value{AS}} simply accepts the directive for source-file
3829 compatibility with such assemblers, but does not actually emit anything
3833 @section @code{.if @var{absolute expression}}
3835 @cindex conditional assembly
3836 @cindex @code{if} directive
3837 @code{.if} marks the beginning of a section of code which is only
3838 considered part of the source program being assembled if the argument
3839 (which must be an @var{absolute expression}) is non-zero. The end of
3840 the conditional section of code must be marked by @code{.endif}
3841 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
3842 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
3843 If you have several conditions to check, @code{.elseif} may be used to avoid
3844 nesting blocks if/else within each subsequent @code{.else} block.
3846 The following variants of @code{.if} are also supported:
3848 @cindex @code{ifdef} directive
3849 @item .ifdef @var{symbol}
3850 Assembles the following section of code if the specified @var{symbol}
3853 @cindex @code{ifc} directive
3854 @item .ifc @var{string1},@var{string2}
3855 Assembles the following section of code if the two strings are the same. The
3856 strings may be optionally quoted with single quotes. If they are not quoted,
3857 the first string stops at the first comma, and the second string stops at the
3858 end of the line. Strings which contain whitespace should be quoted. The
3859 string comparison is case sensitive.
3861 @cindex @code{ifeq} directive
3862 @item .ifeq @var{absolute expression}
3863 Assembles the following section of code if the argument is zero.
3865 @cindex @code{ifeqs} directive
3866 @item .ifeqs @var{string1},@var{string2}
3867 Another form of @code{.ifc}. The strings must be quoted using double quotes.
3869 @cindex @code{ifge} directive
3870 @item .ifge @var{absolute expression}
3871 Assembles the following section of code if the argument is greater than or
3874 @cindex @code{ifgt} directive
3875 @item .ifgt @var{absolute expression}
3876 Assembles the following section of code if the argument is greater than zero.
3878 @cindex @code{ifle} directive
3879 @item .ifle @var{absolute expression}
3880 Assembles the following section of code if the argument is less than or equal
3883 @cindex @code{iflt} directive
3884 @item .iflt @var{absolute expression}
3885 Assembles the following section of code if the argument is less than zero.
3887 @cindex @code{ifnc} directive
3888 @item .ifnc @var{string1},@var{string2}.
3889 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
3890 following section of code if the two strings are not the same.
3892 @cindex @code{ifndef} directive
3893 @cindex @code{ifnotdef} directive
3894 @item .ifndef @var{symbol}
3895 @itemx .ifnotdef @var{symbol}
3896 Assembles the following section of code if the specified @var{symbol}
3897 has not been defined. Both spelling variants are equivalent.
3899 @cindex @code{ifne} directive
3900 @item .ifne @var{absolute expression}
3901 Assembles the following section of code if the argument is not equal to zero
3902 (in other words, this is equivalent to @code{.if}).
3904 @cindex @code{ifnes} directive
3905 @item .ifnes @var{string1},@var{string2}
3906 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
3907 following section of code if the two strings are not the same.
3911 @section @code{.include "@var{file}"}
3913 @cindex @code{include} directive
3914 @cindex supporting files, including
3915 @cindex files, including
3916 This directive provides a way to include supporting files at specified
3917 points in your source program. The code from @var{file} is assembled as
3918 if it followed the point of the @code{.include}; when the end of the
3919 included file is reached, assembly of the original file continues. You
3920 can control the search paths used with the @samp{-I} command-line option
3921 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
3925 @section @code{.int @var{expressions}}
3927 @cindex @code{int} directive
3928 @cindex integers, 32-bit
3929 Expect zero or more @var{expressions}, of any section, separated by commas.
3930 For each expression, emit a number that, at run time, is the value of that
3931 expression. The byte order and bit size of the number depends on what kind
3932 of target the assembly is for.
3936 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
3937 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
3944 @section @code{.internal @var{names}}
3946 @cindex @code{.internal} directive
3948 This one of the ELF visibility directives. The other two are
3949 @pxref{Hidden,,@code{.hidden}} and @pxref{Protected,,@code{.protected}}
3951 This directive overrides the named symbols default visibility (which is set by
3952 their binding: local, global or weak). The directive sets the visibility to
3953 @code{internal} which means that the symbols are considered to be @code{hidden}
3954 (ie not visible to other components), and that some extra, processor specific
3955 processing must also be performed upon the symbols as well.
3959 @section @code{.irp @var{symbol},@var{values}}@dots{}
3961 @cindex @code{irp} directive
3962 Evaluate a sequence of statements assigning different values to @var{symbol}.
3963 The sequence of statements starts at the @code{.irp} directive, and is
3964 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
3965 set to @var{value}, and the sequence of statements is assembled. If no
3966 @var{value} is listed, the sequence of statements is assembled once, with
3967 @var{symbol} set to the null string. To refer to @var{symbol} within the
3968 sequence of statements, use @var{\symbol}.
3970 For example, assembling
3978 is equivalent to assembling
3987 @section @code{.irpc @var{symbol},@var{values}}@dots{}
3989 @cindex @code{irpc} directive
3990 Evaluate a sequence of statements assigning different values to @var{symbol}.
3991 The sequence of statements starts at the @code{.irpc} directive, and is
3992 terminated by an @code{.endr} directive. For each character in @var{value},
3993 @var{symbol} is set to the character, and the sequence of statements is
3994 assembled. If no @var{value} is listed, the sequence of statements is
3995 assembled once, with @var{symbol} set to the null string. To refer to
3996 @var{symbol} within the sequence of statements, use @var{\symbol}.
3998 For example, assembling
4006 is equivalent to assembling
4015 @section @code{.lcomm @var{symbol} , @var{length}}
4017 @cindex @code{lcomm} directive
4018 @cindex local common symbols
4019 @cindex symbols, local common
4020 Reserve @var{length} (an absolute expression) bytes for a local common
4021 denoted by @var{symbol}. The section and value of @var{symbol} are
4022 those of the new local common. The addresses are allocated in the bss
4023 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4024 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4025 not visible to @code{@value{LD}}.
4028 Some targets permit a third argument to be used with @code{.lcomm}. This
4029 argument specifies the desired alignment of the symbol in the bss section.
4033 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4034 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4038 @section @code{.lflags}
4040 @cindex @code{lflags} directive (ignored)
4041 @code{@value{AS}} accepts this directive, for compatibility with other
4042 assemblers, but ignores it.
4044 @ifclear no-line-dir
4046 @section @code{.line @var{line-number}}
4048 @cindex @code{line} directive
4052 @section @code{.ln @var{line-number}}
4054 @cindex @code{ln} directive
4056 @cindex logical line number
4058 Change the logical line number. @var{line-number} must be an absolute
4059 expression. The next line has that logical line number. Therefore any other
4060 statements on the current line (after a statement separator character) are
4061 reported as on logical line number @var{line-number} @minus{} 1. One day
4062 @code{@value{AS}} will no longer support this directive: it is recognized only
4063 for compatibility with existing assembler programs.
4067 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4068 not available; use the synonym @code{.ln} in that context.
4073 @ifclear no-line-dir
4074 Even though this is a directive associated with the @code{a.out} or
4075 @code{b.out} object-code formats, @code{@value{AS}} still recognizes it
4076 when producing COFF output, and treats @samp{.line} as though it
4077 were the COFF @samp{.ln} @emph{if} it is found outside a
4078 @code{.def}/@code{.endef} pair.
4080 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4081 used by compilers to generate auxiliary symbol information for
4086 @section @code{.linkonce [@var{type}]}
4088 @cindex @code{linkonce} directive
4089 @cindex common sections
4090 Mark the current section so that the linker only includes a single copy of it.
4091 This may be used to include the same section in several different object files,
4092 but ensure that the linker will only include it once in the final output file.
4093 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4094 Duplicate sections are detected based on the section name, so it should be
4097 This directive is only supported by a few object file formats; as of this
4098 writing, the only object file format which supports it is the Portable
4099 Executable format used on Windows NT.
4101 The @var{type} argument is optional. If specified, it must be one of the
4102 following strings. For example:
4106 Not all types may be supported on all object file formats.
4110 Silently discard duplicate sections. This is the default.
4113 Warn if there are duplicate sections, but still keep only one copy.
4116 Warn if any of the duplicates have different sizes.
4119 Warn if any of the duplicates do not have exactly the same contents.
4123 @section @code{.ln @var{line-number}}
4125 @cindex @code{ln} directive
4126 @ifclear no-line-dir
4127 @samp{.ln} is a synonym for @samp{.line}.
4130 Tell @code{@value{AS}} to change the logical line number. @var{line-number}
4131 must be an absolute expression. The next line has that logical
4132 line number, so any other statements on the current line (after a
4133 statement separator character @code{;}) are reported as on logical
4134 line number @var{line-number} @minus{} 1.
4137 This directive is accepted, but ignored, when @code{@value{AS}} is
4138 configured for @code{b.out}; its effect is only associated with COFF
4144 @section @code{.mri @var{val}}
4146 @cindex @code{mri} directive
4147 @cindex MRI mode, temporarily
4148 If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If
4149 @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change
4150 affects code assembled until the next @code{.mri} directive, or until the end
4151 of the file. @xref{M, MRI mode, MRI mode}.
4154 @section @code{.list}
4156 @cindex @code{list} directive
4157 @cindex listing control, turning on
4158 Control (in conjunction with the @code{.nolist} directive) whether or
4159 not assembly listings are generated. These two directives maintain an
4160 internal counter (which is zero initially). @code{.list} increments the
4161 counter, and @code{.nolist} decrements it. Assembly listings are
4162 generated whenever the counter is greater than zero.
4164 By default, listings are disabled. When you enable them (with the
4165 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4166 the initial value of the listing counter is one.
4169 @section @code{.long @var{expressions}}
4171 @cindex @code{long} directive
4172 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4175 @c no one seems to know what this is for or whether this description is
4176 @c what it really ought to do
4178 @section @code{.lsym @var{symbol}, @var{expression}}
4180 @cindex @code{lsym} directive
4181 @cindex symbol, not referenced in assembly
4182 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4183 the hash table, ensuring it cannot be referenced by name during the
4184 rest of the assembly. This sets the attributes of the symbol to be
4185 the same as the expression value:
4187 @var{other} = @var{descriptor} = 0
4188 @var{type} = @r{(section of @var{expression})}
4189 @var{value} = @var{expression}
4192 The new symbol is not flagged as external.
4196 @section @code{.macro}
4199 The commands @code{.macro} and @code{.endm} allow you to define macros that
4200 generate assembly output. For example, this definition specifies a macro
4201 @code{sum} that puts a sequence of numbers into memory:
4204 .macro sum from=0, to=5
4213 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4225 @item .macro @var{macname}
4226 @itemx .macro @var{macname} @var{macargs} @dots{}
4227 @cindex @code{macro} directive
4228 Begin the definition of a macro called @var{macname}. If your macro
4229 definition requires arguments, specify their names after the macro name,
4230 separated by commas or spaces. You can supply a default value for any
4231 macro argument by following the name with @samp{=@var{deflt}}. For
4232 example, these are all valid @code{.macro} statements:
4236 Begin the definition of a macro called @code{comm}, which takes no
4239 @item .macro plus1 p, p1
4240 @itemx .macro plus1 p p1
4241 Either statement begins the definition of a macro called @code{plus1},
4242 which takes two arguments; within the macro definition, write
4243 @samp{\p} or @samp{\p1} to evaluate the arguments.
4245 @item .macro reserve_str p1=0 p2
4246 Begin the definition of a macro called @code{reserve_str}, with two
4247 arguments. The first argument has a default value, but not the second.
4248 After the definition is complete, you can call the macro either as
4249 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4250 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4251 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4252 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4255 When you call a macro, you can specify the argument values either by
4256 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4257 @samp{sum to=17, from=9}.
4260 @cindex @code{endm} directive
4261 Mark the end of a macro definition.
4264 @cindex @code{exitm} directive
4265 Exit early from the current macro definition.
4267 @cindex number of macros executed
4268 @cindex macros, count executed
4270 @code{@value{AS}} maintains a counter of how many macros it has
4271 executed in this pseudo-variable; you can copy that number to your
4272 output with @samp{\@@}, but @emph{only within a macro definition}.
4275 @item LOCAL @var{name} [ , @dots{} ]
4276 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4277 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4278 Alternate macro syntax}.
4280 Generate a string replacement for each of the @var{name} arguments, and
4281 replace any instances of @var{name} in each macro expansion. The
4282 replacement string is unique in the assembly, and different for each
4283 separate macro expansion. @code{LOCAL} allows you to write macros that
4284 define symbols, without fear of conflict between separate macro expansions.
4289 @section @code{.nolist}
4291 @cindex @code{nolist} directive
4292 @cindex listing control, turning off
4293 Control (in conjunction with the @code{.list} directive) whether or
4294 not assembly listings are generated. These two directives maintain an
4295 internal counter (which is zero initially). @code{.list} increments the
4296 counter, and @code{.nolist} decrements it. Assembly listings are
4297 generated whenever the counter is greater than zero.
4300 @section @code{.octa @var{bignums}}
4302 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4303 @cindex @code{octa} directive
4304 @cindex integer, 16-byte
4305 @cindex sixteen byte integer
4306 This directive expects zero or more bignums, separated by commas. For each
4307 bignum, it emits a 16-byte integer.
4309 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4310 hence @emph{octa}-word for 16 bytes.
4313 @section @code{.org @var{new-lc} , @var{fill}}
4315 @cindex @code{org} directive
4316 @cindex location counter, advancing
4317 @cindex advancing location counter
4318 @cindex current address, advancing
4319 Advance the location counter of the current section to
4320 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4321 expression with the same section as the current subsection. That is,
4322 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4323 wrong section, the @code{.org} directive is ignored. To be compatible
4324 with former assemblers, if the section of @var{new-lc} is absolute,
4325 @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4326 is the same as the current subsection.
4328 @code{.org} may only increase the location counter, or leave it
4329 unchanged; you cannot use @code{.org} to move the location counter
4332 @c double negative used below "not undefined" because this is a specific
4333 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4334 @c section. doc@cygnus.com 18feb91
4335 Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4336 may not be undefined. If you really detest this restriction we eagerly await
4337 a chance to share your improved assembler.
4339 Beware that the origin is relative to the start of the section, not
4340 to the start of the subsection. This is compatible with other
4341 people's assemblers.
4343 When the location counter (of the current subsection) is advanced, the
4344 intervening bytes are filled with @var{fill} which should be an
4345 absolute expression. If the comma and @var{fill} are omitted,
4346 @var{fill} defaults to zero.
4349 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4351 @cindex padding the location counter given a power of two
4352 @cindex @code{p2align} directive
4353 Pad the location counter (in the current subsection) to a particular
4354 storage boundary. The first expression (which must be absolute) is the
4355 number of low-order zero bits the location counter must have after
4356 advancement. For example @samp{.p2align 3} advances the location
4357 counter until it a multiple of 8. If the location counter is already a
4358 multiple of 8, no change is needed.
4360 The second expression (also absolute) gives the fill value to be stored in the
4361 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4362 padding bytes are normally zero. However, on some systems, if the section is
4363 marked as containing code and the fill value is omitted, the space is filled
4364 with no-op instructions.
4366 The third expression is also absolute, and is also optional. If it is present,
4367 it is the maximum number of bytes that should be skipped by this alignment
4368 directive. If doing the alignment would require skipping more bytes than the
4369 specified maximum, then the alignment is not done at all. You can omit the
4370 fill value (the second argument) entirely by simply using two commas after the
4371 required alignment; this can be useful if you want the alignment to be filled
4372 with no-op instructions when appropriate.
4374 @cindex @code{p2alignw} directive
4375 @cindex @code{p2alignl} directive
4376 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4377 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4378 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4379 fill pattern as a four byte longword value. For example, @code{.p2alignw
4380 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4381 filled in with the value 0x368d (the exact placement of the bytes depends upon
4382 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4387 @section @code{.previous}
4389 @cindex @code{.previous} directive
4390 @cindex Section Stack
4391 This is one of the ELF section stack manipulation directives. The others are
4392 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4395 This directive swaps the current section (and subsection) with most recently
4396 referenced section (and subsection) prior to this one. Multiple
4397 @code{.previous} directives in a row will flip between two sections (and their
4400 In terms of the section stack, this directive swaps the current section with
4401 the top section on the section stack.
4406 @section @code{.popsection}
4408 @cindex @code{.popsection} directive
4409 @cindex Section Stack
4410 This is one of the ELF section stack manipulation directives. The others are
4411 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4414 This directive replaces the current section (and subsection) with the top
4415 section (and subsection) on the section stack. This section is popped off the
4420 @section @code{.print @var{string}}
4422 @cindex @code{print} directive
4423 @code{@value{AS}} will print @var{string} on the standard output during
4424 assembly. You must put @var{string} in double quotes.
4428 @section @code{.protected @var{names}}
4430 @cindex @code{.protected} directive
4432 This one of the ELF visibility directives. The other two are
4433 @pxref{Hidden} and @pxref{Internal}
4435 This directive overrides the named symbols default visibility (which is set by
4436 their binding: local, global or weak). The directive sets the visibility to
4437 @code{protected} which means that any references to the symbols from within the
4438 components that defines them must be resolved to the definition in that
4439 component, even if a definition in another component would normally preempt
4444 @section @code{.psize @var{lines} , @var{columns}}
4446 @cindex @code{psize} directive
4447 @cindex listing control: paper size
4448 @cindex paper size, for listings
4449 Use this directive to declare the number of lines---and, optionally, the
4450 number of columns---to use for each page, when generating listings.
4452 If you do not use @code{.psize}, listings use a default line-count
4453 of 60. You may omit the comma and @var{columns} specification; the
4454 default width is 200 columns.
4456 @code{@value{AS}} generates formfeeds whenever the specified number of
4457 lines is exceeded (or whenever you explicitly request one, using
4460 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4461 those explicitly specified with @code{.eject}.
4464 @section @code{.purgem @var{name}}
4466 @cindex @code{purgem} directive
4467 Undefine the macro @var{name}, so that later uses of the string will not be
4468 expanded. @xref{Macro}.
4472 @section @code{.pushsection @var{name} , @var{subsection}}
4474 @cindex @code{.pushsection} directive
4475 @cindex Section Stack
4476 This is one of the ELF section stack manipulation directives. The others are
4477 @pxref{Section}, @xref{SubSection}, @pxref{PopSection}, and
4480 This directive is a synonym for @code{.section}. It psuhes the current section
4481 (and subsection) onto the top of the section stack, and then replaces the
4482 current section and subsection with @code{name} and @code{subsection}.
4486 @section @code{.quad @var{bignums}}
4488 @cindex @code{quad} directive
4489 @code{.quad} expects zero or more bignums, separated by commas. For
4490 each bignum, it emits
4492 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4493 warning message; and just takes the lowest order 8 bytes of the bignum.
4494 @cindex eight-byte integer
4495 @cindex integer, 8-byte
4497 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4498 hence @emph{quad}-word for 8 bytes.
4501 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4502 warning message; and just takes the lowest order 16 bytes of the bignum.
4503 @cindex sixteen-byte integer
4504 @cindex integer, 16-byte
4508 @section @code{.rept @var{count}}
4510 @cindex @code{rept} directive
4511 Repeat the sequence of lines between the @code{.rept} directive and the next
4512 @code{.endr} directive @var{count} times.
4514 For example, assembling
4522 is equivalent to assembling
4531 @section @code{.sbttl "@var{subheading}"}
4533 @cindex @code{sbttl} directive
4534 @cindex subtitles for listings
4535 @cindex listing control: subtitle
4536 Use @var{subheading} as the title (third line, immediately after the
4537 title line) when generating assembly listings.
4539 This directive affects subsequent pages, as well as the current page if
4540 it appears within ten lines of the top of a page.
4544 @section @code{.scl @var{class}}
4546 @cindex @code{scl} directive
4547 @cindex symbol storage class (COFF)
4548 @cindex COFF symbol storage class
4549 Set the storage-class value for a symbol. This directive may only be
4550 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4551 whether a symbol is static or external, or it may record further
4552 symbolic debugging information.
4555 The @samp{.scl} directive is primarily associated with COFF output; when
4556 configured to generate @code{b.out} output format, @code{@value{AS}}
4557 accepts this directive but ignores it.
4562 @section @code{.section @var{name}} (COFF version)
4564 @cindex @code{section} directive
4565 @cindex named section
4566 Use the @code{.section} directive to assemble the following code into a section
4569 This directive is only supported for targets that actually support arbitrarily
4570 named sections; on @code{a.out} targets, for example, it is not accepted, even
4571 with a standard @code{a.out} section name.
4573 For COFF targets, the @code{.section} directive is used in one of the following
4577 .section @var{name}[, "@var{flags}"]
4578 .section @var{name}[, @var{subsegment}]
4581 If the optional argument is quoted, it is taken as flags to use for the
4582 section. Each flag is a single character. The following flags are recognized:
4585 bss section (uninitialized data)
4587 section is not loaded
4597 shared section (meaningful for PE targets)
4600 If no flags are specified, the default flags depend upon the section name. If
4601 the section name is not recognized, the default will be for the section to be
4602 loaded and writable.
4604 If the optional argument to the @code{.section} directive is not quoted, it is
4605 taken as a subsegment number (@pxref{Sub-Sections}).
4608 @section @code{.section @var{name}} (ELF version)
4610 @cindex @code{section} directive
4611 @cindex named section
4613 @cindex Section Stack
4614 This is one of the ELF section stack manipulation directives. The others are
4615 @xref{SubSection}, @pxref{PushSection}@pxref{PopSection}, and
4619 For ELF targets, the @code{.section} directive is used like this:
4622 .section @var{name} [, "@var{flags}"[, @@@var{type}]]
4625 The optional @var{flags} argument is a quoted string which may contain any
4626 combintion of the following characters:
4629 section is allocatable
4633 section is executable
4636 The optional @var{type} argument may contain one of the following constants:
4639 section contains data
4641 section does not contain data (i.e., section only occupies space)
4644 If no flags are specified, the default flags depend upon the section name. If
4645 the section name is not recognized, the default will be for the section to have
4646 none of the above flags: it will not be allocated in memory, nor writable, nor
4647 executable. The section will contain data.
4649 For ELF targets, the assembler supports another type of @code{.section}
4650 directive for compatibility with the Solaris assembler:
4653 .section "@var{name}"[, @var{flags}...]
4656 Note that the section name is quoted. There may be a sequence of comma
4660 section is allocatable
4664 section is executable
4667 This directive replaces the current section and subsection. The replaced
4668 section and subsection are pushed onto the section stack. See the contents of
4669 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
4670 how this directive and the other section stack directives work.
4673 @section @code{.set @var{symbol}, @var{expression}}
4675 @cindex @code{set} directive
4676 @cindex symbol value, setting
4677 Set the value of @var{symbol} to @var{expression}. This
4678 changes @var{symbol}'s value and type to conform to
4679 @var{expression}. If @var{symbol} was flagged as external, it remains
4680 flagged (@pxref{Symbol Attributes}).
4682 You may @code{.set} a symbol many times in the same assembly.
4684 If you @code{.set} a global symbol, the value stored in the object
4685 file is the last value stored into it.
4688 The syntax for @code{set} on the HPPA is
4689 @samp{@var{symbol} .set @var{expression}}.
4693 @section @code{.short @var{expressions}}
4695 @cindex @code{short} directive
4697 @code{.short} is normally the same as @samp{.word}.
4698 @xref{Word,,@code{.word}}.
4700 In some configurations, however, @code{.short} and @code{.word} generate
4701 numbers of different lengths; @pxref{Machine Dependencies}.
4705 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
4708 This expects zero or more @var{expressions}, and emits
4709 a 16 bit number for each.
4714 @section @code{.single @var{flonums}}
4716 @cindex @code{single} directive
4717 @cindex floating point numbers (single)
4718 This directive assembles zero or more flonums, separated by commas. It
4719 has the same effect as @code{.float}.
4721 The exact kind of floating point numbers emitted depends on how
4722 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
4726 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
4727 numbers in @sc{ieee} format.
4732 @section @code{.size} (COFF version)
4734 @cindex @code{size} directive
4735 This directive is generated by compilers to include auxiliary debugging
4736 information in the symbol table. It is only permitted inside
4737 @code{.def}/@code{.endef} pairs.
4740 @samp{.size} is only meaningful when generating COFF format output; when
4741 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4745 @section @code{.size @var{name} , @var{expression}} (ELF version)
4746 @cindex @code{size} directive
4748 This directive is used to set the size associated with a symbol @var{name}.
4749 The size in bytes is computed from @var{expression} which can make use of label
4750 arithmetic. This directive is typically used to set the size of function
4754 @section @code{.sleb128 @var{expressions}}
4756 @cindex @code{sleb128} directive
4757 @var{sleb128} stands for ``signed little endian base 128.'' This is a
4758 compact, variable length representation of numbers used by the DWARF
4759 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
4761 @ifclear no-space-dir
4763 @section @code{.skip @var{size} , @var{fill}}
4765 @cindex @code{skip} directive
4766 @cindex filling memory
4767 This directive emits @var{size} bytes, each of value @var{fill}. Both
4768 @var{size} and @var{fill} are absolute expressions. If the comma and
4769 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
4773 @section @code{.space @var{size} , @var{fill}}
4775 @cindex @code{space} directive
4776 @cindex filling memory
4777 This directive emits @var{size} bytes, each of value @var{fill}. Both
4778 @var{size} and @var{fill} are absolute expressions. If the comma
4779 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
4784 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
4785 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
4786 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
4787 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
4796 @section @code{.space}
4797 @cindex @code{space} directive
4799 On the AMD 29K, this directive is ignored; it is accepted for
4800 compatibility with other AMD 29K assemblers.
4803 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
4804 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
4810 @section @code{.stabd, .stabn, .stabs}
4812 @cindex symbolic debuggers, information for
4813 @cindex @code{stab@var{x}} directives
4814 There are three directives that begin @samp{.stab}.
4815 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
4816 The symbols are not entered in the @code{@value{AS}} hash table: they
4817 cannot be referenced elsewhere in the source file.
4818 Up to five fields are required:
4822 This is the symbol's name. It may contain any character except
4823 @samp{\000}, so is more general than ordinary symbol names. Some
4824 debuggers used to code arbitrarily complex structures into symbol names
4828 An absolute expression. The symbol's type is set to the low 8 bits of
4829 this expression. Any bit pattern is permitted, but @code{@value{LD}}
4830 and debuggers choke on silly bit patterns.
4833 An absolute expression. The symbol's ``other'' attribute is set to the
4834 low 8 bits of this expression.
4837 An absolute expression. The symbol's descriptor is set to the low 16
4838 bits of this expression.
4841 An absolute expression which becomes the symbol's value.
4844 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
4845 or @code{.stabs} statement, the symbol has probably already been created;
4846 you get a half-formed symbol in your object file. This is
4847 compatible with earlier assemblers!
4850 @cindex @code{stabd} directive
4851 @item .stabd @var{type} , @var{other} , @var{desc}
4853 The ``name'' of the symbol generated is not even an empty string.
4854 It is a null pointer, for compatibility. Older assemblers used a
4855 null pointer so they didn't waste space in object files with empty
4858 The symbol's value is set to the location counter,
4859 relocatably. When your program is linked, the value of this symbol
4860 is the address of the location counter when the @code{.stabd} was
4863 @cindex @code{stabn} directive
4864 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
4865 The name of the symbol is set to the empty string @code{""}.
4867 @cindex @code{stabs} directive
4868 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
4869 All five fields are specified.
4875 @section @code{.string} "@var{str}"
4877 @cindex string, copying to object file
4878 @cindex @code{string} directive
4880 Copy the characters in @var{str} to the object file. You may specify more than
4881 one string to copy, separated by commas. Unless otherwise specified for a
4882 particular machine, the assembler marks the end of each string with a 0 byte.
4883 You can use any of the escape sequences described in @ref{Strings,,Strings}.
4886 @section @code{.struct @var{expression}}
4888 @cindex @code{struct} directive
4889 Switch to the absolute section, and set the section offset to @var{expression},
4890 which must be an absolute expression. You might use this as follows:
4899 This would define the symbol @code{field1} to have the value 0, the symbol
4900 @code{field2} to have the value 4, and the symbol @code{field3} to have the
4901 value 8. Assembly would be left in the absolute section, and you would need to
4902 use a @code{.section} directive of some sort to change to some other section
4903 before further assembly.
4907 @section @code{.subsection @var{name}}
4909 @cindex @code{.subsection} directive
4910 @cindex Section Stack
4911 This is one of the ELF section stack manipulation directives. The others are
4912 @pxref{Section}, @xref{PushSection}, @pxref{PopSection}, and
4915 This directive replaces the current subsection with @code{name}. The current
4916 section is not changed. The replaced subsection is put onto the section stack
4917 in place of the then current top of stack subsection.
4922 @section @code{.symver}
4923 @cindex @code{symver} directive
4924 @cindex symbol versioning
4925 @cindex versions of symbols
4926 Use the @code{.symver} directive to bind symbols to specific version nodes
4927 within a source file. This is only supported on ELF platforms, and is
4928 typically used when assembling files to be linked into a shared library.
4929 There are cases where it may make sense to use this in objects to be bound
4930 into an application itself so as to override a versioned symbol from a
4933 For ELF targets, the @code{.symver} directive can be used like this:
4935 .symver @var{name}, @var{name2@@nodename}
4937 If the symbol @var{name} is defined within the file
4938 being assembled, the @code{.symver} directive effectively creates a symbol
4939 alias with the name @var{name2@@nodename}, and in fact the main reason that we
4940 just don't try and create a regular alias is that the @var{@@} character isn't
4941 permitted in symbol names. The @var{name2} part of the name is the actual name
4942 of the symbol by which it will be externally referenced. The name @var{name}
4943 itself is merely a name of convenience that is used so that it is possible to
4944 have definitions for multiple versions of a function within a single source
4945 file, and so that the compiler can unambiguously know which version of a
4946 function is being mentioned. The @var{nodename} portion of the alias should be
4947 the name of a node specified in the version script supplied to the linker when
4948 building a shared library. If you are attempting to override a versioned
4949 symbol from a shared library, then @var{nodename} should correspond to the
4950 nodename of the symbol you are trying to override.
4952 If the symbol @var{name} is not defined within the file being assembled, all
4953 references to @var{name} will be changed to @var{name2@@nodename}. If no
4954 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
4957 Another usage of the @code{.symver} directive is:
4959 .symver @var{name}, @var{name2@@@@nodename}
4961 In this case, the symbol @var{name} must exist and be defined within
4962 the file being assembled. It is similiar to @var{name2@@nodename}. The
4963 difference is @var{name2@@@@nodename} will also be used to resolve
4964 references to @var{name2} by the linker.
4966 The third usage of the @code{.symver} directive is:
4968 .symver @var{name}, @var{name2@@@@@@nodename}
4970 When @var{name} is not defined within the
4971 file being assembled, it is treated as @var{name2@@nodename}. When
4972 @var{name} is defined within the file being assembled, the symbol
4973 name, @var{name}, will be changed to @var{name2@@@@nodename}.
4978 @section @code{.tag @var{structname}}
4980 @cindex COFF structure debugging
4981 @cindex structure debugging, COFF
4982 @cindex @code{tag} directive
4983 This directive is generated by compilers to include auxiliary debugging
4984 information in the symbol table. It is only permitted inside
4985 @code{.def}/@code{.endef} pairs. Tags are used to link structure
4986 definitions in the symbol table with instances of those structures.
4989 @samp{.tag} is only used when generating COFF format output; when
4990 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4996 @section @code{.text @var{subsection}}
4998 @cindex @code{text} directive
4999 Tells @code{@value{AS}} to assemble the following statements onto the end of
5000 the text subsection numbered @var{subsection}, which is an absolute
5001 expression. If @var{subsection} is omitted, subsection number zero
5005 @section @code{.title "@var{heading}"}
5007 @cindex @code{title} directive
5008 @cindex listing control: title line
5009 Use @var{heading} as the title (second line, immediately after the
5010 source file name and pagenumber) when generating assembly listings.
5012 This directive affects subsequent pages, as well as the current page if
5013 it appears within ten lines of the top of a page.
5016 @section @code{.type @var{int}} (COFF version)
5018 @cindex COFF symbol type
5019 @cindex symbol type, COFF
5020 @cindex @code{type} directive
5021 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5022 records the integer @var{int} as the type attribute of a symbol table entry.
5025 @samp{.type} is associated only with COFF format output; when
5026 @code{@value{AS}} is configured for @code{b.out} output, it accepts this
5027 directive but ignores it.
5030 @section @code{.type @var{name} , @var{type description}} (ELF version)
5032 @cindex ELF symbol type
5033 @cindex symbol type, ELF
5034 @cindex @code{type} directive
5035 This directive is used to set the type of symbol @var{name} to be either a
5036 function symbol or an ojbect symbol. There are five different syntaxes
5037 supported for the @var{type description} field, in order to provide
5038 comptability with various other assemblers. The syntaxes supported are:
5041 .type <name>,#function
5042 .type <name>,#object
5044 .type <name>,@@function
5045 .type <name>,@@object
5047 .type <name>,%function
5048 .type <name>,%object
5050 .type <name>,"function"
5051 .type <name>,"object"
5053 .type <name> STT_FUNCTION
5054 .type <name> STT_OBJECT
5058 @section @code{.uleb128 @var{expressions}}
5060 @cindex @code{uleb128} directive
5061 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5062 compact, variable length representation of numbers used by the DWARF
5063 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5067 @section @code{.val @var{addr}}
5069 @cindex @code{val} directive
5070 @cindex COFF value attribute
5071 @cindex value attribute, COFF
5072 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5073 records the address @var{addr} as the value attribute of a symbol table
5077 @samp{.val} is used only for COFF output; when @code{@value{AS}} is
5078 configured for @code{b.out}, it accepts this directive but ignores it.
5084 @section @code{.version "@var{string}"}
5086 @cindex @code{.version}
5087 This directive creates a @code{.note} section and places into it an ELF
5088 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5093 @section @code{.vtable_entry @var{table}, @var{offset}}
5095 @cindex @code{.vtable_entry}
5096 This directive finds or creates a symbol @code{table} and creates a
5097 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5100 @section @code{.vtable_inherit @var{child}, @var{parent}}
5102 @cindex @code{.vtable_inherit}
5103 This directive finds the symbol @code{child} and finds or creates the symbol
5104 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5105 parent whoes addend is the value of the child symbol. As a special case the
5106 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5111 @section @code{.weak @var{names}}
5113 @cindex @code{.weak}
5114 This directive sets the weak attribute on the comma seperated list of symbol
5115 @code{names}. If the symbols do not already exist, they will be created.
5119 @section @code{.word @var{expressions}}
5121 @cindex @code{word} directive
5122 This directive expects zero or more @var{expressions}, of any section,
5123 separated by commas.
5126 For each expression, @code{@value{AS}} emits a 32-bit number.
5129 For each expression, @code{@value{AS}} emits a 16-bit number.
5134 The size of the number emitted, and its byte order,
5135 depend on what target computer the assembly is for.
5138 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5139 @c happen---32-bit addressability, period; no long/short jumps.
5140 @ifset DIFF-TBL-KLUGE
5141 @cindex difference tables altered
5142 @cindex altered difference tables
5144 @emph{Warning: Special Treatment to support Compilers}
5148 Machines with a 32-bit address space, but that do less than 32-bit
5149 addressing, require the following special treatment. If the machine of
5150 interest to you does 32-bit addressing (or doesn't require it;
5151 @pxref{Machine Dependencies}), you can ignore this issue.
5154 In order to assemble compiler output into something that works,
5155 @code{@value{AS}} occasionlly does strange things to @samp{.word} directives.
5156 Directives of the form @samp{.word sym1-sym2} are often emitted by
5157 compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
5158 directive of the form @samp{.word sym1-sym2}, and the difference between
5159 @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}}
5160 creates a @dfn{secondary jump table}, immediately before the next label.
5161 This secondary jump table is preceded by a short-jump to the
5162 first byte after the secondary table. This short-jump prevents the flow
5163 of control from accidentally falling into the new table. Inside the
5164 table is a long-jump to @code{sym2}. The original @samp{.word}
5165 contains @code{sym1} minus the address of the long-jump to
5168 If there were several occurrences of @samp{.word sym1-sym2} before the
5169 secondary jump table, all of them are adjusted. If there was a
5170 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5171 long-jump to @code{sym4} is included in the secondary jump table,
5172 and the @code{.word} directives are adjusted to contain @code{sym3}
5173 minus the address of the long-jump to @code{sym4}; and so on, for as many
5174 entries in the original jump table as necessary.
5177 @emph{This feature may be disabled by compiling @code{@value{AS}} with the
5178 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5179 assembly language programmers.
5182 @c end DIFF-TBL-KLUGE
5185 @section Deprecated Directives
5187 @cindex deprecated directives
5188 @cindex obsolescent directives
5189 One day these directives won't work.
5190 They are included for compatibility with older assemblers.
5197 @node Machine Dependencies
5198 @chapter Machine Dependent Features
5200 @cindex machine dependencies
5201 The machine instruction sets are (almost by definition) different on
5202 each machine where @code{@value{AS}} runs. Floating point representations
5203 vary as well, and @code{@value{AS}} often supports a few additional
5204 directives or command-line options for compatibility with other
5205 assemblers on a particular platform. Finally, some versions of
5206 @code{@value{AS}} support special pseudo-instructions for branch
5209 This chapter discusses most of these differences, though it does not
5210 include details on any machine's instruction set. For details on that
5211 subject, see the hardware manufacturer's manual.
5215 * AMD29K-Dependent:: AMD 29K Dependent Features
5218 * ARC-Dependent:: ARC Dependent Features
5221 * ARM-Dependent:: ARM Dependent Features
5224 * D10V-Dependent:: D10V Dependent Features
5227 * D30V-Dependent:: D30V Dependent Features
5230 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5233 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5236 * HPPA-Dependent:: HPPA Dependent Features
5239 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5242 * i386-Dependent:: Intel 80386 Dependent Features
5245 * i860-Dependent:: Intel 80860 Dependent Features
5248 * i960-Dependent:: Intel 80960 Dependent Features
5251 * M32R-Dependent:: M32R Dependent Features
5254 * M68K-Dependent:: M680x0 Dependent Features
5257 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5260 * MIPS-Dependent:: MIPS Dependent Features
5263 * SH-Dependent:: Hitachi SH Dependent Features
5266 * PJ-Dependent:: picoJava Dependent Features
5269 * Sparc-Dependent:: SPARC Dependent Features
5272 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5275 * V850-Dependent:: V850 Dependent Features
5278 * Z8000-Dependent:: Z8000 Dependent Features
5281 * Vax-Dependent:: VAX Dependent Features
5288 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5289 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5290 @c peculiarity: to preserve cross-references, there must be a node called
5291 @c "Machine Dependencies". Hence the conditional nodenames in each
5292 @c major node below. Node defaulting in makeinfo requires adjacency of
5293 @c node and sectioning commands; hence the repetition of @chapter BLAH
5294 @c in both conditional blocks.
5300 @chapter ARC Dependent Features
5303 @node Machine Dependencies
5304 @chapter ARC Dependent Features
5309 * ARC-Opts:: Options
5310 * ARC-Float:: Floating Point
5311 * ARC-Directives:: Sparc Machine Directives
5317 @cindex options for ARC
5319 @cindex architectures, ARC
5320 @cindex ARC architectures
5321 The ARC chip family includes several successive levels (or other
5322 variants) of chip, using the same core instruction set, but including
5323 a few additional instructions at each level.
5325 By default, @code{@value{AS}} assumes the core instruction set (ARC
5326 base). The @code{.cpu} pseudo-op is intended to be used to select
5330 @cindex @code{-mbig-endian} option (ARC)
5331 @cindex @code{-mlittle-endian} option (ARC)
5332 @cindex ARC big-endian output
5333 @cindex ARC little-endian output
5334 @cindex big-endian output, ARC
5335 @cindex little-endian output, ARC
5337 @itemx -mlittle-endian
5338 Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or
5339 little-endian output at run time (unlike most other @sc{gnu} development
5340 tools, which must be configured for one or the other). Use
5341 @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian}
5346 @section Floating Point
5348 @cindex floating point, ARC (@sc{ieee})
5349 @cindex ARC floating point (@sc{ieee})
5350 The ARC cpu family currently does not have hardware floating point
5351 support. Software floating point support is provided by @code{GCC}
5352 and uses @sc{ieee} floating-point numbers.
5354 @node ARC-Directives
5355 @section ARC Machine Directives
5357 @cindex ARC machine directives
5358 @cindex machine directives, ARC
5359 The ARC version of @code{@value{AS}} supports the following additional
5364 @cindex @code{cpu} directive, SPARC
5365 This must be followed by the desired cpu.
5366 The ARC is intended to be customizable, @code{.cpu} is used to
5367 select the desired variant [though currently there are none].
5374 @include c-a29k.texi
5383 @node Machine Dependencies
5384 @chapter Machine Dependent Features
5386 The machine instruction sets are different on each Hitachi chip family,
5387 and there are also some syntax differences among the families. This
5388 chapter describes the specific @code{@value{AS}} features for each
5392 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5393 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5394 * SH-Dependent:: Hitachi SH Dependent Features
5401 @include c-d10v.texi
5405 @include c-d30v.texi
5409 @include c-h8300.texi
5413 @include c-h8500.texi
5417 @include c-hppa.texi
5421 @include c-i370.texi
5425 @include c-i386.texi
5429 @include c-i860.texi
5433 @include c-i960.texi
5437 @include c-m32r.texi
5441 @include c-m68k.texi
5445 @include c-m68hc11.texi
5449 @include c-mips.texi
5453 @include c-ns32k.texi
5465 @include c-sparc.texi
5469 @include c-tic54x.texi
5481 @include c-v850.texi
5485 @c reverse effect of @down at top of generic Machine-Dep chapter
5489 @node Reporting Bugs
5490 @chapter Reporting Bugs
5491 @cindex bugs in assembler
5492 @cindex reporting bugs in assembler
5494 Your bug reports play an essential role in making @code{@value{AS}} reliable.
5496 Reporting a bug may help you by bringing a solution to your problem, or it may
5497 not. But in any case the principal function of a bug report is to help the
5498 entire community by making the next version of @code{@value{AS}} work better.
5499 Bug reports are your contribution to the maintenance of @code{@value{AS}}.
5501 In order for a bug report to serve its purpose, you must include the
5502 information that enables us to fix the bug.
5505 * Bug Criteria:: Have you found a bug?
5506 * Bug Reporting:: How to report bugs
5510 @section Have you found a bug?
5511 @cindex bug criteria
5513 If you are not sure whether you have found a bug, here are some guidelines:
5516 @cindex fatal signal
5517 @cindex assembler crash
5518 @cindex crash of assembler
5520 If the assembler gets a fatal signal, for any input whatever, that is a
5521 @code{@value{AS}} bug. Reliable assemblers never crash.
5523 @cindex error on valid input
5525 If @code{@value{AS}} produces an error message for valid input, that is a bug.
5527 @cindex invalid input
5529 If @code{@value{AS}} does not produce an error message for invalid input, that
5530 is a bug. However, you should note that your idea of ``invalid input'' might
5531 be our idea of ``an extension'' or ``support for traditional practice''.
5534 If you are an experienced user of assemblers, your suggestions for improvement
5535 of @code{@value{AS}} are welcome in any case.
5539 @section How to report bugs
5541 @cindex assembler bugs, reporting
5543 A number of companies and individuals offer support for @sc{gnu} products. If
5544 you obtained @code{@value{AS}} from a support organization, we recommend you
5545 contact that organization first.
5547 You can find contact information for many support companies and
5548 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5551 In any event, we also recommend that you send bug reports for @code{@value{AS}}
5552 to @samp{bug-gnu-utils@@gnu.org}.
5554 The fundamental principle of reporting bugs usefully is this:
5555 @strong{report all the facts}. If you are not sure whether to state a
5556 fact or leave it out, state it!
5558 Often people omit facts because they think they know what causes the problem
5559 and assume that some details do not matter. Thus, you might assume that the
5560 name of a symbol you use in an example does not matter. Well, probably it does
5561 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5562 happens to fetch from the location where that name is stored in memory;
5563 perhaps, if the name were different, the contents of that location would fool
5564 the assembler into doing the right thing despite the bug. Play it safe and
5565 give a specific, complete example. That is the easiest thing for you to do,
5566 and the most helpful.
5568 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5569 it is new to us. Therefore, always write your bug reports on the assumption
5570 that the bug has not been reported previously.
5572 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5573 bell?'' Those bug reports are useless, and we urge everyone to
5574 @emph{refuse to respond to them} except to chide the sender to report
5577 To enable us to fix the bug, you should include all these things:
5581 The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start
5582 it with the @samp{--version} argument.
5584 Without this, we will not know whether there is any point in looking for
5585 the bug in the current version of @code{@value{AS}}.
5588 Any patches you may have applied to the @code{@value{AS}} source.
5591 The type of machine you are using, and the operating system name and
5595 What compiler (and its version) was used to compile @code{@value{AS}}---e.g.
5599 The command arguments you gave the assembler to assemble your example and
5600 observe the bug. To guarantee you will not omit something important, list them
5601 all. A copy of the Makefile (or the output from make) is sufficient.
5603 If we were to try to guess the arguments, we would probably guess wrong
5604 and then we might not encounter the bug.
5607 A complete input file that will reproduce the bug. If the bug is observed when
5608 the assembler is invoked via a compiler, send the assembler source, not the
5609 high level language source. Most compilers will produce the assembler source
5610 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5611 the options @samp{-v --save-temps}; this will save the assembler source in a
5612 file with an extension of @file{.s}, and also show you exactly how
5613 @code{@value{AS}} is being run.
5616 A description of what behavior you observe that you believe is
5617 incorrect. For example, ``It gets a fatal signal.''
5619 Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we
5620 will certainly notice it. But if the bug is incorrect output, we might not
5621 notice unless it is glaringly wrong. You might as well not give us a chance to
5624 Even if the problem you experience is a fatal signal, you should still say so
5625 explicitly. Suppose something strange is going on, such as, your copy of
5626 @code{@value{AS}} is out of synch, or you have encountered a bug in the C
5627 library on your system. (This has happened!) Your copy might crash and ours
5628 would not. If you told us to expect a crash, then when ours fails to crash, we
5629 would know that the bug was not happening for us. If you had not told us to
5630 expect a crash, then we would not be able to draw any conclusion from our
5634 If you wish to suggest changes to the @code{@value{AS}} source, send us context
5635 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5636 option. Always send diffs from the old file to the new file. If you even
5637 discuss something in the @code{@value{AS}} source, refer to it by context, not
5640 The line numbers in our development sources will not match those in your
5641 sources. Your line numbers would convey no useful information to us.
5644 Here are some things that are not necessary:
5648 A description of the envelope of the bug.
5650 Often people who encounter a bug spend a lot of time investigating
5651 which changes to the input file will make the bug go away and which
5652 changes will not affect it.
5654 This is often time consuming and not very useful, because the way we
5655 will find the bug is by running a single example under the debugger
5656 with breakpoints, not by pure deduction from a series of examples.
5657 We recommend that you save your time for something else.
5659 Of course, if you can find a simpler example to report @emph{instead}
5660 of the original one, that is a convenience for us. Errors in the
5661 output will be easier to spot, running under the debugger will take
5662 less time, and so on.
5664 However, simplification is not vital; if you do not want to do this,
5665 report the bug anyway and send us the entire test case you used.
5668 A patch for the bug.
5670 A patch for the bug does help us if it is a good one. But do not omit
5671 the necessary information, such as the test case, on the assumption that
5672 a patch is all we need. We might see problems with your patch and decide
5673 to fix the problem another way, or we might not understand it at all.
5675 Sometimes with a program as complicated as @code{@value{AS}} it is very hard to
5676 construct an example that will make the program follow a certain path through
5677 the code. If you do not send us the example, we will not be able to construct
5678 one, so we will not be able to verify that the bug is fixed.
5680 And if we cannot understand what bug you are trying to fix, or why your
5681 patch should be an improvement, we will not install it. A test case will
5682 help us to understand.
5685 A guess about what the bug is or what it depends on.
5687 Such guesses are usually wrong. Even we cannot guess right about such
5688 things without first using the debugger to find the facts.
5691 @node Acknowledgements
5692 @chapter Acknowledgements
5694 If you have contributed to @code{@value{AS}} and your name isn't listed here,
5695 it is not meant as a slight. We just don't know about it. Send mail to the
5696 maintainer, and we'll correct the situation. Currently
5698 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
5700 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
5703 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
5704 information and the 68k series machines, most of the preprocessing pass, and
5705 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
5707 K. Richard Pixley maintained GAS for a while, adding various enhancements and
5708 many bug fixes, including merging support for several processors, breaking GAS
5709 up to handle multiple object file format back ends (including heavy rewrite,
5710 testing, an integration of the coff and b.out back ends), adding configuration
5711 including heavy testing and verification of cross assemblers and file splits
5712 and renaming, converted GAS to strictly ANSI C including full prototypes, added
5713 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
5714 port (including considerable amounts of reverse engineering), a SPARC opcode
5715 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
5716 assertions and made them work, much other reorganization, cleanup, and lint.
5718 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
5719 in format-specific I/O modules.
5721 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
5722 has done much work with it since.
5724 The Intel 80386 machine description was written by Eliot Dresselhaus.
5726 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
5728 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
5729 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
5731 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
5732 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
5733 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
5734 support a.out format.
5736 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
5737 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
5738 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
5739 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
5742 John Gilmore built the AMD 29000 support, added @code{.include} support, and
5743 simplified the configuration of which versions accept which directives. He
5744 updated the 68k machine description so that Motorola's opcodes always produced
5745 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
5746 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
5747 cross-compilation support, and one bug in relaxation that took a week and
5748 required the proverbial one-bit fix.
5750 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
5751 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
5752 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
5753 PowerPC assembler, and made a few other minor patches.
5755 Steve Chamberlain made @code{@value{AS}} able to generate listings.
5757 Hewlett-Packard contributed support for the HP9000/300.
5759 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
5760 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
5761 formats). This work was supported by both the Center for Software Science at
5762 the University of Utah and Cygnus Support.
5764 Support for ELF format files has been worked on by Mark Eichin of Cygnus
5765 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
5766 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
5767 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
5768 and some initial 64-bit support).
5770 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
5772 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
5773 support for openVMS/Alpha.
5775 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
5778 Several engineers at Cygnus Support have also provided many small bug fixes and
5779 configuration enhancements.
5781 Many others have contributed large or small bugfixes and enhancements. If
5782 you have contributed significant work and are not mentioned on this list, and
5783 want to be, let us know. Some of the history has been lost; we are not
5784 intentionally leaving anyone out.
5786 @node GNU Free Documentation License
5787 @chapter GNU Free Documentation License
5789 GNU Free Documentation License
5791 Version 1.1, March 2000
5793 Copyright (C) 2000 Free Software Foundation, Inc.
5794 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
5796 Everyone is permitted to copy and distribute verbatim copies
5797 of this license document, but changing it is not allowed.
5802 The purpose of this License is to make a manual, textbook, or other
5803 written document "free" in the sense of freedom: to assure everyone
5804 the effective freedom to copy and redistribute it, with or without
5805 modifying it, either commercially or noncommercially. Secondarily,
5806 this License preserves for the author and publisher a way to get
5807 credit for their work, while not being considered responsible for
5808 modifications made by others.
5810 This License is a kind of "copyleft", which means that derivative
5811 works of the document must themselves be free in the same sense. It
5812 complements the GNU General Public License, which is a copyleft
5813 license designed for free software.
5815 We have designed this License in order to use it for manuals for free
5816 software, because free software needs free documentation: a free
5817 program should come with manuals providing the same freedoms that the
5818 software does. But this License is not limited to software manuals;
5819 it can be used for any textual work, regardless of subject matter or
5820 whether it is published as a printed book. We recommend this License
5821 principally for works whose purpose is instruction or reference.
5824 1. APPLICABILITY AND DEFINITIONS
5826 This License applies to any manual or other work that contains a
5827 notice placed by the copyright holder saying it can be distributed
5828 under the terms of this License. The "Document", below, refers to any
5829 such manual or work. Any member of the public is a licensee, and is
5832 A "Modified Version" of the Document means any work containing the
5833 Document or a portion of it, either copied verbatim, or with
5834 modifications and/or translated into another language.
5836 A "Secondary Section" is a named appendix or a front-matter section of
5837 the Document that deals exclusively with the relationship of the
5838 publishers or authors of the Document to the Document's overall subject
5839 (or to related matters) and contains nothing that could fall directly
5840 within that overall subject. (For example, if the Document is in part a
5841 textbook of mathematics, a Secondary Section may not explain any
5842 mathematics.) The relationship could be a matter of historical
5843 connection with the subject or with related matters, or of legal,
5844 commercial, philosophical, ethical or political position regarding
5847 The "Invariant Sections" are certain Secondary Sections whose titles
5848 are designated, as being those of Invariant Sections, in the notice
5849 that says that the Document is released under this License.
5851 The "Cover Texts" are certain short passages of text that are listed,
5852 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
5853 the Document is released under this License.
5855 A "Transparent" copy of the Document means a machine-readable copy,
5856 represented in a format whose specification is available to the
5857 general public, whose contents can be viewed and edited directly and
5858 straightforwardly with generic text editors or (for images composed of
5859 pixels) generic paint programs or (for drawings) some widely available
5860 drawing editor, and that is suitable for input to text formatters or
5861 for automatic translation to a variety of formats suitable for input
5862 to text formatters. A copy made in an otherwise Transparent file
5863 format whose markup has been designed to thwart or discourage
5864 subsequent modification by readers is not Transparent. A copy that is
5865 not "Transparent" is called "Opaque".
5867 Examples of suitable formats for Transparent copies include plain
5868 ASCII without markup, Texinfo input format, LaTeX input format, SGML
5869 or XML using a publicly available DTD, and standard-conforming simple
5870 HTML designed for human modification. Opaque formats include
5871 PostScript, PDF, proprietary formats that can be read and edited only
5872 by proprietary word processors, SGML or XML for which the DTD and/or
5873 processing tools are not generally available, and the
5874 machine-generated HTML produced by some word processors for output
5877 The "Title Page" means, for a printed book, the title page itself,
5878 plus such following pages as are needed to hold, legibly, the material
5879 this License requires to appear in the title page. For works in
5880 formats which do not have any title page as such, "Title Page" means
5881 the text near the most prominent appearance of the work's title,
5882 preceding the beginning of the body of the text.
5887 You may copy and distribute the Document in any medium, either
5888 commercially or noncommercially, provided that this License, the
5889 copyright notices, and the license notice saying this License applies
5890 to the Document are reproduced in all copies, and that you add no other
5891 conditions whatsoever to those of this License. You may not use
5892 technical measures to obstruct or control the reading or further
5893 copying of the copies you make or distribute. However, you may accept
5894 compensation in exchange for copies. If you distribute a large enough
5895 number of copies you must also follow the conditions in section 3.
5897 You may also lend copies, under the same conditions stated above, and
5898 you may publicly display copies.
5901 3. COPYING IN QUANTITY
5903 If you publish printed copies of the Document numbering more than 100,
5904 and the Document's license notice requires Cover Texts, you must enclose
5905 the copies in covers that carry, clearly and legibly, all these Cover
5906 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
5907 the back cover. Both covers must also clearly and legibly identify
5908 you as the publisher of these copies. The front cover must present
5909 the full title with all words of the title equally prominent and
5910 visible. You may add other material on the covers in addition.
5911 Copying with changes limited to the covers, as long as they preserve
5912 the title of the Document and satisfy these conditions, can be treated
5913 as verbatim copying in other respects.
5915 If the required texts for either cover are too voluminous to fit
5916 legibly, you should put the first ones listed (as many as fit
5917 reasonably) on the actual cover, and continue the rest onto adjacent
5920 If you publish or distribute Opaque copies of the Document numbering
5921 more than 100, you must either include a machine-readable Transparent
5922 copy along with each Opaque copy, or state in or with each Opaque copy
5923 a publicly-accessible computer-network location containing a complete
5924 Transparent copy of the Document, free of added material, which the
5925 general network-using public has access to download anonymously at no
5926 charge using public-standard network protocols. If you use the latter
5927 option, you must take reasonably prudent steps, when you begin
5928 distribution of Opaque copies in quantity, to ensure that this
5929 Transparent copy will remain thus accessible at the stated location
5930 until at least one year after the last time you distribute an Opaque
5931 copy (directly or through your agents or retailers) of that edition to
5934 It is requested, but not required, that you contact the authors of the
5935 Document well before redistributing any large number of copies, to give
5936 them a chance to provide you with an updated version of the Document.
5941 You may copy and distribute a Modified Version of the Document under
5942 the conditions of sections 2 and 3 above, provided that you release
5943 the Modified Version under precisely this License, with the Modified
5944 Version filling the role of the Document, thus licensing distribution
5945 and modification of the Modified Version to whoever possesses a copy
5946 of it. In addition, you must do these things in the Modified Version:
5948 A. Use in the Title Page (and on the covers, if any) a title distinct
5949 from that of the Document, and from those of previous versions
5950 (which should, if there were any, be listed in the History section
5951 of the Document). You may use the same title as a previous version
5952 if the original publisher of that version gives permission.
5953 B. List on the Title Page, as authors, one or more persons or entities
5954 responsible for authorship of the modifications in the Modified
5955 Version, together with at least five of the principal authors of the
5956 Document (all of its principal authors, if it has less than five).
5957 C. State on the Title page the name of the publisher of the
5958 Modified Version, as the publisher.
5959 D. Preserve all the copyright notices of the Document.
5960 E. Add an appropriate copyright notice for your modifications
5961 adjacent to the other copyright notices.
5962 F. Include, immediately after the copyright notices, a license notice
5963 giving the public permission to use the Modified Version under the
5964 terms of this License, in the form shown in the Addendum below.
5965 G. Preserve in that license notice the full lists of Invariant Sections
5966 and required Cover Texts given in the Document's license notice.
5967 H. Include an unaltered copy of this License.
5968 I. Preserve the section entitled "History", and its title, and add to
5969 it an item stating at least the title, year, new authors, and
5970 publisher of the Modified Version as given on the Title Page. If
5971 there is no section entitled "History" in the Document, create one
5972 stating the title, year, authors, and publisher of the Document as
5973 given on its Title Page, then add an item describing the Modified
5974 Version as stated in the previous sentence.
5975 J. Preserve the network location, if any, given in the Document for
5976 public access to a Transparent copy of the Document, and likewise
5977 the network locations given in the Document for previous versions
5978 it was based on. These may be placed in the "History" section.
5979 You may omit a network location for a work that was published at
5980 least four years before the Document itself, or if the original
5981 publisher of the version it refers to gives permission.
5982 K. In any section entitled "Acknowledgements" or "Dedications",
5983 preserve the section's title, and preserve in the section all the
5984 substance and tone of each of the contributor acknowledgements
5985 and/or dedications given therein.
5986 L. Preserve all the Invariant Sections of the Document,
5987 unaltered in their text and in their titles. Section numbers
5988 or the equivalent are not considered part of the section titles.
5989 M. Delete any section entitled "Endorsements". Such a section
5990 may not be included in the Modified Version.
5991 N. Do not retitle any existing section as "Endorsements"
5992 or to conflict in title with any Invariant Section.
5994 If the Modified Version includes new front-matter sections or
5995 appendices that qualify as Secondary Sections and contain no material
5996 copied from the Document, you may at your option designate some or all
5997 of these sections as invariant. To do this, add their titles to the
5998 list of Invariant Sections in the Modified Version's license notice.
5999 These titles must be distinct from any other section titles.
6001 You may add a section entitled "Endorsements", provided it contains
6002 nothing but endorsements of your Modified Version by various
6003 parties--for example, statements of peer review or that the text has
6004 been approved by an organization as the authoritative definition of a
6007 You may add a passage of up to five words as a Front-Cover Text, and a
6008 passage of up to 25 words as a Back-Cover Text, to the end of the list
6009 of Cover Texts in the Modified Version. Only one passage of
6010 Front-Cover Text and one of Back-Cover Text may be added by (or
6011 through arrangements made by) any one entity. If the Document already
6012 includes a cover text for the same cover, previously added by you or
6013 by arrangement made by the same entity you are acting on behalf of,
6014 you may not add another; but you may replace the old one, on explicit
6015 permission from the previous publisher that added the old one.
6017 The author(s) and publisher(s) of the Document do not by this License
6018 give permission to use their names for publicity for or to assert or
6019 imply endorsement of any Modified Version.
6022 5. COMBINING DOCUMENTS
6024 You may combine the Document with other documents released under this
6025 License, under the terms defined in section 4 above for modified
6026 versions, provided that you include in the combination all of the
6027 Invariant Sections of all of the original documents, unmodified, and
6028 list them all as Invariant Sections of your combined work in its
6031 The combined work need only contain one copy of this License, and
6032 multiple identical Invariant Sections may be replaced with a single
6033 copy. If there are multiple Invariant Sections with the same name but
6034 different contents, make the title of each such section unique by
6035 adding at the end of it, in parentheses, the name of the original
6036 author or publisher of that section if known, or else a unique number.
6037 Make the same adjustment to the section titles in the list of
6038 Invariant Sections in the license notice of the combined work.
6040 In the combination, you must combine any sections entitled "History"
6041 in the various original documents, forming one section entitled
6042 "History"; likewise combine any sections entitled "Acknowledgements",
6043 and any sections entitled "Dedications". You must delete all sections
6044 entitled "Endorsements."
6047 6. COLLECTIONS OF DOCUMENTS
6049 You may make a collection consisting of the Document and other documents
6050 released under this License, and replace the individual copies of this
6051 License in the various documents with a single copy that is included in
6052 the collection, provided that you follow the rules of this License for
6053 verbatim copying of each of the documents in all other respects.
6055 You may extract a single document from such a collection, and distribute
6056 it individually under this License, provided you insert a copy of this
6057 License into the extracted document, and follow this License in all
6058 other respects regarding verbatim copying of that document.
6061 7. AGGREGATION WITH INDEPENDENT WORKS
6063 A compilation of the Document or its derivatives with other separate
6064 and independent documents or works, in or on a volume of a storage or
6065 distribution medium, does not as a whole count as a Modified Version
6066 of the Document, provided no compilation copyright is claimed for the
6067 compilation. Such a compilation is called an "aggregate", and this
6068 License does not apply to the other self-contained works thus compiled
6069 with the Document, on account of their being thus compiled, if they
6070 are not themselves derivative works of the Document.
6072 If the Cover Text requirement of section 3 is applicable to these
6073 copies of the Document, then if the Document is less than one quarter
6074 of the entire aggregate, the Document's Cover Texts may be placed on
6075 covers that surround only the Document within the aggregate.
6076 Otherwise they must appear on covers around the whole aggregate.
6081 Translation is considered a kind of modification, so you may
6082 distribute translations of the Document under the terms of section 4.
6083 Replacing Invariant Sections with translations requires special
6084 permission from their copyright holders, but you may include
6085 translations of some or all Invariant Sections in addition to the
6086 original versions of these Invariant Sections. You may include a
6087 translation of this License provided that you also include the
6088 original English version of this License. In case of a disagreement
6089 between the translation and the original English version of this
6090 License, the original English version will prevail.
6095 You may not copy, modify, sublicense, or distribute the Document except
6096 as expressly provided for under this License. Any other attempt to
6097 copy, modify, sublicense or distribute the Document is void, and will
6098 automatically terminate your rights under this License. However,
6099 parties who have received copies, or rights, from you under this
6100 License will not have their licenses terminated so long as such
6101 parties remain in full compliance.
6104 10. FUTURE REVISIONS OF THIS LICENSE
6106 The Free Software Foundation may publish new, revised versions
6107 of the GNU Free Documentation License from time to time. Such new
6108 versions will be similar in spirit to the present version, but may
6109 differ in detail to address new problems or concerns. See
6110 http://www.gnu.org/copyleft/.
6112 Each version of the License is given a distinguishing version number.
6113 If the Document specifies that a particular numbered version of this
6114 License "or any later version" applies to it, you have the option of
6115 following the terms and conditions either of that specified version or
6116 of any later version that has been published (not as a draft) by the
6117 Free Software Foundation. If the Document does not specify a version
6118 number of this License, you may choose any version ever published (not
6119 as a draft) by the Free Software Foundation.
6122 ADDENDUM: How to use this License for your documents
6124 To use this License in a document you have written, include a copy of
6125 the License in the document and put the following copyright and
6126 license notices just after the title page:
6129 Copyright (c) YEAR YOUR NAME.
6130 Permission is granted to copy, distribute and/or modify this document
6131 under the terms of the GNU Free Documentation License, Version 1.1
6132 or any later version published by the Free Software Foundation;
6133 with the Invariant Sections being LIST THEIR TITLES, with the
6134 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6135 A copy of the license is included in the section entitled "GNU
6136 Free Documentation License".
6139 If you have no Invariant Sections, write "with no Invariant Sections"
6140 instead of saying which ones are invariant. If you have no
6141 Front-Cover Texts, write "no Front-Cover Texts" instead of
6142 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6144 If your document contains nontrivial examples of program code, we
6145 recommend releasing these examples in parallel under your choice of
6146 free software license, such as the GNU General Public License,
6147 to permit their use in free software.
projects / external / binutils.git / blob