1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
4 @c Free Software Foundation, Inc.
5 @c UPDATE!! On future updates--
6 @c (1) check for new machine-dep cmdline options in
7 @c md_parse_option definitions in config/tc-*.c
8 @c (2) for platform-specific directives, examine md_pseudo_op
10 @c (3) for object-format specific directives, examine obj_pseudo_op
12 @c (4) portable directives in potable[] in read.c
16 @macro gcctabopt{body}
19 @c defaults, config file may override:
22 @include asconfig.texi
27 @c Configure for the generation of man pages
63 @c common OR combinations of conditions
83 @set abnormal-separator
87 @settitle Using @value{AS}
90 @settitle Using @value{AS} (@value{TARGET})
92 @setchapternewpage odd
97 @c WARE! Some of the machine-dependent sections contain tables of machine
98 @c instructions. Except in multi-column format, these tables look silly.
99 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
100 @c the multi-col format is faked within @example sections.
102 @c Again unfortunately, the natural size that fits on a page, for these tables,
103 @c is different depending on whether or not smallbook is turned on.
104 @c This matters, because of order: text flow switches columns at each page
107 @c The format faked in this source works reasonably well for smallbook,
108 @c not well for the default large-page format. This manual expects that if you
109 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
110 @c tables in question. You can turn on one without the other at your
111 @c discretion, of course.
114 @c the insn tables look just as silly in info files regardless of smallbook,
115 @c might as well show 'em anyways.
121 * As: (as). The GNU assembler.
122 * Gas: (as). The GNU assembler.
131 This file documents the GNU Assembler "@value{AS}".
133 @c man begin COPYRIGHT
134 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
136 Permission is granted to copy, distribute and/or modify this document
137 under the terms of the GNU Free Documentation License, Version 1.1
138 or any later version published by the Free Software Foundation;
139 with no Invariant Sections, with no Front-Cover Texts, and with no
140 Back-Cover Texts. A copy of the license is included in the
141 section entitled "GNU Free Documentation License".
146 Permission is granted to process this file through Tex and print the
147 results, provided the printed document carries copying permission
148 notice identical to this one except for the removal of this paragraph
149 (this paragraph not being relevant to the printed manual).
155 @title Using @value{AS}
156 @subtitle The @sc{gnu} Assembler
158 @subtitle for the @value{TARGET} family
161 @subtitle Version @value{VERSION}
164 The Free Software Foundation Inc. thanks The Nice Computer
165 Company of Australia for loaning Dean Elsner to write the
166 first (Vax) version of @command{as} for Project @sc{gnu}.
167 The proprietors, management and staff of TNCCA thank FSF for
168 distracting the boss while they got some work
171 @author Dean Elsner, Jay Fenlason & friends
175 \hfill {\it Using {\tt @value{AS}}}\par
176 \hfill Edited by Cygnus Support\par
178 %"boxit" macro for figures:
179 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
180 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
181 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
182 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
183 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
186 @vskip 0pt plus 1filll
187 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
189 Permission is granted to copy, distribute and/or modify this document
190 under the terms of the GNU Free Documentation License, Version 1.1
191 or any later version published by the Free Software Foundation;
192 with no Invariant Sections, with no Front-Cover Texts, and with no
193 Back-Cover Texts. A copy of the license is included in the
194 section entitled "GNU Free Documentation License".
200 @top Using @value{AS}
202 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
205 This version of the file describes @command{@value{AS}} configured to generate
206 code for @value{TARGET} architectures.
209 This document is distributed under the terms of the GNU Free
210 Documentation License. A copy of the license is included in the
211 section entitled "GNU Free Documentation License".
214 * Overview:: Overview
215 * Invoking:: Command-Line Options
217 * Sections:: Sections and Relocation
219 * Expressions:: Expressions
220 * Pseudo Ops:: Assembler Directives
221 * Machine Dependencies:: Machine Dependent Features
222 * Reporting Bugs:: Reporting Bugs
223 * Acknowledgements:: Who Did What
224 * GNU Free Documentation License:: GNU Free Documentation License
232 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
234 This version of the manual describes @command{@value{AS}} configured to generate
235 code for @value{TARGET} architectures.
239 @cindex invocation summary
240 @cindex option summary
241 @cindex summary of options
242 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
243 @pxref{Invoking,,Comand-Line Options}.
245 @c man title AS the portable GNU assembler.
249 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
253 @c We don't use deffn and friends for the following because they seem
254 @c to be limited to one line for the header.
256 @c man begin SYNOPSIS
257 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
258 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
259 [@b{-J}] [@b{-K}] [@b{-L}]
260 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
261 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
262 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
263 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
264 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
265 [@b{--}|@var{files} @dots{}]
267 @c Target dependent options are listed below. Keep the list sorted.
268 @c Add an empty line for separation.
270 @c am29k has no machine-dependent assembler options
274 @emph{Target Alpha options:}
276 [@b{-mdebug} | @b{-no-mdebug}]
277 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
278 [@b{-F}] [@b{-32addr}]
282 @emph{Target ARC options:}
288 @emph{Target ARM options:}
289 @c Don't document the deprecated options
290 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
291 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
292 [@b{-mfpu}=@var{floating-point-fromat}]
295 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
296 @b{-mapcs-reentrant}]
297 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
301 @emph{Target CRIS options:}
302 [@b{--underscore} | @b{--no-underscore}]
304 [@b{--emulation=criself} | @b{--emulation=crisaout}]
305 @c Deprecated -- deliberately not documented.
310 @emph{Target D10V options:}
315 @emph{Target D30V options:}
316 [@b{-O}|@b{-n}|@b{-N}]
319 @c Hitachi family chips have no machine-dependent assembler options
322 @c HPPA has no machine-dependent assembler options (yet).
326 @emph{Target i386 options:}
331 @emph{Target i960 options:}
332 @c see md_parse_option in tc-i960.c
333 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
335 [@b{-b}] [@b{-no-relax}]
339 @emph{Target IA-64 options:}
340 [@b{-mconstant-gp}|@b{-mauto-pic}]
341 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
343 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
347 @emph{Target M32R options:}
348 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
353 @emph{Target M680X0 options:}
354 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
358 @emph{Target M68HC11 options:}
359 [@b{-m68hc11}|@b{-m68hc12}]
360 [@b{--force-long-branchs}] [@b{--short-branchs}]
361 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
362 [@b{--print-opcodes}] [@b{--generate-example}]
366 @emph{Target MCORE options:}
367 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
368 [@b{-mcpu=[210|340]}]
372 @emph{Target MIPS options:}
373 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-n}] [@b{-O}[@var{optimization level}]]
374 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
375 [@b{-non_shared}] [@b{-xgot}] [@b{--membedded-pic}]
376 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
377 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
378 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips64}]
379 [@b{-construct-floats}] [@b{-no-construct-floats}]
380 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
381 [@b{-mfix7000}] [@b{-mno-fix7000}]
382 [@b{-mips16}] [@b{-no-mips16}]
383 [@b{-mips3d}] [@b{-no-mips3d}]
384 [@b{-mdmx}] [@b{-no-mdmx}]
385 [@b{-mdebug}] [@b{-no-mdebug}]
389 @emph{Target MMIX options:}
390 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
391 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
392 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
393 [@b{--linker-allocated-gregs}]
397 @emph{Target PDP11 options:}
398 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
399 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
400 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
404 @emph{Target picoJava options:}
409 @emph{Target PowerPC options:}
410 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
411 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
412 @b{-mbooke32}|@b{-mbooke64}]
413 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
414 [@b{-mregnames}|@b{-mno-regnames}]
415 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
416 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
417 [@b{-msolaris}|@b{-mno-solaris}]
421 @emph{Target SPARC options:}
422 @c The order here is important. See c-sparc.texi.
423 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
424 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
425 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
430 @emph{Target TIC54X options:}
431 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
432 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
435 @c Z8000 has no machine-dependent assembler options
444 Turn on listings, in any of a variety of ways:
448 omit false conditionals
451 omit debugging directives
454 include high-level source
460 include macro expansions
463 omit forms processing
469 set the name of the listing file
472 You may combine these options; for example, use @samp{-aln} for assembly
473 listing without forms processing. The @samp{=file} option, if used, must be
474 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
477 Ignored. This option is accepted for script compatibility with calls to
480 @item --defsym @var{sym}=@var{value}
481 Define the symbol @var{sym} to be @var{value} before assembling the input file.
482 @var{value} must be an integer constant. As in C, a leading @samp{0x}
483 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
486 ``fast''---skip whitespace and comment preprocessing (assume source is
490 Generate stabs debugging information for each assembler line. This
491 may help debugging assembler code, if the debugger can handle it.
494 Generate DWARF2 debugging information for each assembler line. This
495 may help debugging assembler code, if the debugger can handle it. Note - this
496 option is only supported by some targets, not all of them.
499 Print a summary of the command line options and exit.
502 Print a summary of all target specific options and exit.
505 Add directory @var{dir} to the search list for @code{.include} directives.
508 Don't warn about signed overflow.
511 @ifclear DIFF-TBL-KLUGE
512 This option is accepted but has no effect on the @value{TARGET} family.
514 @ifset DIFF-TBL-KLUGE
515 Issue warnings when difference tables altered for long displacements.
520 Keep (in the symbol table) local symbols. On traditional a.out systems
521 these start with @samp{L}, but different systems have different local
524 @item --listing-lhs-width=@var{number}
525 Set the maximum width, in words, of the output data column for an assembler
526 listing to @var{number}.
528 @item --listing-lhs-width2=@var{number}
529 Set the maximum width, in words, of the output data column for continuation
530 lines in an assembler listing to @var{number}.
532 @item --listing-rhs-width=@var{number}
533 Set the maximum width of an input source line, as displayed in a listing, to
536 @item --listing-cont-lines=@var{number}
537 Set the maximum number of lines printed in a listing for a single line of input
540 @item -o @var{objfile}
541 Name the object-file output from @command{@value{AS}} @var{objfile}.
544 Fold the data section into the text section.
547 Print the maximum space (in bytes) and total time (in seconds) used by
550 @item --strip-local-absolute
551 Remove local absolute symbols from the outgoing symbol table.
555 Print the @command{as} version.
558 Print the @command{as} version and exit.
562 Suppress warning messages.
564 @item --fatal-warnings
565 Treat warnings as errors.
568 Don't suppress warning messages or treat them as errors.
577 Generate an object file even after errors.
579 @item -- | @var{files} @dots{}
580 Standard input, or source files to assemble.
585 The following options are available when @value{AS} is configured for
590 This option selects the core processor variant.
592 Select either big-endian (-EB) or little-endian (-EL) output.
597 The following options are available when @value{AS} is configured for the ARM
601 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
602 Specify which ARM processor variant is the target.
603 @item -march=@var{architecture}[+@var{extension}@dots{}]
604 Specify which ARM architecture variant is used by the target.
605 @item -mfpu=@var{floating-point-format}
606 Select which Floating Point architecture is the target.
608 Enable Thumb only instruction decoding.
609 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
610 Select which procedure calling convention is in use.
612 Select either big-endian (-EB) or little-endian (-EL) output.
613 @item -mthumb-interwork
614 Specify that the code has been generated with interworking between Thumb and
617 Specify that PIC code has been generated.
622 See the info pages for documentation of the CRIS-specific options.
626 The following options are available when @value{AS} is configured for
629 @cindex D10V optimization
630 @cindex optimization, D10V
632 Optimize output by parallelizing instructions.
637 The following options are available when @value{AS} is configured for a D30V
640 @cindex D30V optimization
641 @cindex optimization, D30V
643 Optimize output by parallelizing instructions.
647 Warn when nops are generated.
649 @cindex D30V nops after 32-bit multiply
651 Warn when a nop after a 32-bit multiply instruction is generated.
656 The following options are available when @value{AS} is configured for the
657 Intel 80960 processor.
660 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
661 Specify which variant of the 960 architecture is the target.
664 Add code to collect statistics about branches taken.
667 Do not alter compare-and-branch instructions for long displacements;
674 The following options are available when @value{AS} is configured for the
675 Mitsubishi M32R series.
680 Specify which processor in the M32R family is the target. The default
681 is normally the M32R, but this option changes it to the M32RX.
683 @item --warn-explicit-parallel-conflicts or --Wp
684 Produce warning messages when questionable parallel constructs are
687 @item --no-warn-explicit-parallel-conflicts or --Wnp
688 Do not produce warning messages when questionable parallel constructs are
695 The following options are available when @value{AS} is configured for the
696 Motorola 68000 series.
701 Shorten references to undefined symbols, to one word instead of two.
703 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
704 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
705 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
706 Specify what processor in the 68000 family is the target. The default
707 is normally the 68020, but this can be changed at configuration time.
709 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
710 The target machine does (or does not) have a floating-point coprocessor.
711 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
712 the basic 68000 is not compatible with the 68881, a combination of the
713 two can be specified, since it's possible to do emulation of the
714 coprocessor instructions with the main processor.
716 @item -m68851 | -mno-68851
717 The target machine does (or does not) have a memory-management
718 unit coprocessor. The default is to assume an MMU for 68020 and up.
725 For details about the PDP-11 machine dependent features options,
726 see @ref{PDP-11-Options}.
729 @item -mpic | -mno-pic
730 Generate position-independent (or position-dependent) code. The
731 default is @option{-mpic}.
734 @itemx -mall-extensions
735 Enable all instruction set extensions. This is the default.
737 @item -mno-extensions
738 Disable all instruction set extensions.
740 @item -m@var{extension} | -mno-@var{extension}
741 Enable (or disable) a particular instruction set extension.
744 Enable the instruction set extensions supported by a particular CPU, and
745 disable all other extensions.
747 @item -m@var{machine}
748 Enable the instruction set extensions supported by a particular machine
749 model, and disable all other extensions.
755 The following options are available when @value{AS} is configured for
756 a picoJava processor.
760 @cindex PJ endianness
761 @cindex endianness, PJ
762 @cindex big endian output, PJ
764 Generate ``big endian'' format output.
766 @cindex little endian output, PJ
768 Generate ``little endian'' format output.
774 The following options are available when @value{AS} is configured for the
775 Motorola 68HC11 or 68HC12 series.
779 @item -m68hc11 | -m68hc12
780 Specify what processor is the target. The default is
781 defined by the configuration option when building the assembler.
783 @item --force-long-branchs
784 Relative branches are turned into absolute ones. This concerns
785 conditional branches, unconditional branches and branches to a
788 @item -S | --short-branchs
789 Do not turn relative branchs into absolute ones
790 when the offset is out of range.
792 @item --strict-direct-mode
793 Do not turn the direct addressing mode into extended addressing mode
794 when the instruction does not support direct addressing mode.
796 @item --print-insn-syntax
797 Print the syntax of instruction in case of error.
799 @item --print-opcodes
800 print the list of instructions with syntax and then exit.
802 @item --generate-example
803 print an example of instruction for each possible instruction and then exit.
804 This option is only useful for testing @command{@value{AS}}.
810 The following options are available when @command{@value{AS}} is configured
811 for the SPARC architecture:
814 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
815 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
816 Explicitly select a variant of the SPARC architecture.
818 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
819 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
821 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
822 UltraSPARC extensions.
824 @item -xarch=v8plus | -xarch=v8plusa
825 For compatibility with the Solaris v9 assembler. These options are
826 equivalent to -Av8plus and -Av8plusa, respectively.
829 Warn when the assembler switches to another architecture.
834 The following options are available when @value{AS} is configured for the 'c54x
839 Enable extended addressing mode. All addresses and relocations will assume
840 extended addressing (usually 23 bits).
841 @item -mcpu=@var{CPU_VERSION}
842 Sets the CPU version being compiled for.
843 @item -merrors-to-file @var{FILENAME}
844 Redirect error output to a file, for broken systems which don't support such
845 behaviour in the shell.
850 The following options are available when @value{AS} is configured for
851 a @sc{mips} processor.
855 This option sets the largest size of an object that can be referenced
856 implicitly with the @code{gp} register. It is only accepted for targets that
857 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
859 @cindex MIPS endianness
860 @cindex endianness, MIPS
861 @cindex big endian output, MIPS
863 Generate ``big endian'' format output.
865 @cindex little endian output, MIPS
867 Generate ``little endian'' format output.
877 Generate code for a particular @sc{mips} Instruction Set Architecture level.
878 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
879 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
880 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
881 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond to generic
882 @samp{MIPS V}, @samp{MIPS32}, and @samp{MIPS64} ISA processors,
885 @item -march=@var{CPU}
886 Generate code for a particular @sc{mips} cpu.
888 @item -mtune=@var{cpu}
889 Schedule and tune for a particular @sc{mips} cpu.
893 Cause nops to be inserted if the read of the destination register
894 of an mfhi or mflo instruction occurs in the following two instructions.
898 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
899 section instead of the standard ELF .stabs sections.
903 The register sizes are normally inferred from the ISA and ABI, but these
904 flags force a certain group of registers to be treated as 32 bits wide at
905 all times. @samp{-mgp32} controls the size of general-purpose registers
906 and @samp{-mfp32} controls the size of floating-point registers.
910 Generate code for the MIPS 16 processor. This is equivalent to putting
911 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
912 turns off this option.
916 Generate code for the MIPS-3D Application Specific Extension.
917 This tells the assembler to accept MIPS-3D instructions.
918 @samp{-no-mips3d} turns off this option.
922 Generate code for the MDMX Application Specific Extension.
923 This tells the assembler to accept MDMX instructions.
924 @samp{-no-mdmx} turns off this option.
926 @item --construct-floats
927 @itemx --no-construct-floats
928 The @samp{--no-construct-floats} option disables the construction of
929 double width floating point constants by loading the two halves of the
930 value into the two single width floating point registers that make up
931 the double width register. By default @samp{--construct-floats} is
932 selected, allowing construction of these floating point constants.
935 @item --emulation=@var{name}
936 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
937 for some other target, in all respects, including output format (choosing
938 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
939 debugging information or store symbol table information, and default
940 endianness. The available configuration names are: @samp{mipsecoff},
941 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
942 @samp{mipsbelf}. The first two do not alter the default endianness from that
943 of the primary target for which the assembler was configured; the others change
944 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
945 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
946 selection in any case.
948 This option is currently supported only when the primary target
949 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
950 Furthermore, the primary target or others specified with
951 @samp{--enable-targets=@dots{}} at configuration time must include support for
952 the other format, if both are to be available. For example, the Irix 5
953 configuration includes support for both.
955 Eventually, this option will support more configurations, with more
956 fine-grained control over the assembler's behavior, and will be supported for
960 @command{@value{AS}} ignores this option. It is accepted for compatibility with
967 Control how to deal with multiplication overflow and division by zero.
968 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
969 (and only work for Instruction Set Architecture level 2 and higher);
970 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
974 When this option is used, @command{@value{AS}} will issue a warning every
975 time it generates a nop instruction from a macro.
980 The following options are available when @value{AS} is configured for
986 Enable or disable the JSRI to BSR transformation. By default this is enabled.
987 The command line option @samp{-nojsri2bsr} can be used to disable it.
991 Enable or disable the silicon filter behaviour. By default this is disabled.
992 The default can be overridden by the @samp{-sifilter} command line option.
995 Alter jump instructions for long displacements.
997 @item -mcpu=[210|340]
998 Select the cpu type on the target hardware. This controls which instructions
1002 Assemble for a big endian target.
1005 Assemble for a little endian target.
1011 See the info pages for documentation of the MMIX-specific options.
1017 * Manual:: Structure of this Manual
1018 * GNU Assembler:: The GNU Assembler
1019 * Object Formats:: Object File Formats
1020 * Command Line:: Command Line
1021 * Input Files:: Input Files
1022 * Object:: Output (Object) File
1023 * Errors:: Error and Warning Messages
1027 @section Structure of this Manual
1029 @cindex manual, structure and purpose
1030 This manual is intended to describe what you need to know to use
1031 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1032 notation for symbols, constants, and expressions; the directives that
1033 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1036 We also cover special features in the @value{TARGET}
1037 configuration of @command{@value{AS}}, including assembler directives.
1040 This manual also describes some of the machine-dependent features of
1041 various flavors of the assembler.
1044 @cindex machine instructions (not covered)
1045 On the other hand, this manual is @emph{not} intended as an introduction
1046 to programming in assembly language---let alone programming in general!
1047 In a similar vein, we make no attempt to introduce the machine
1048 architecture; we do @emph{not} describe the instruction set, standard
1049 mnemonics, registers or addressing modes that are standard to a
1050 particular architecture.
1052 You may want to consult the manufacturer's
1053 machine architecture manual for this information.
1057 For information on the H8/300 machine instruction set, see @cite{H8/300
1058 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1059 see @cite{H8/300H Series Programming Manual} (Hitachi).
1062 For information on the H8/500 machine instruction set, see @cite{H8/500
1063 Series Programming Manual} (Hitachi M21T001).
1066 For information on the Hitachi SH machine instruction set, see
1067 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1070 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1074 @c I think this is premature---doc@cygnus.com, 17jan1991
1076 Throughout this manual, we assume that you are running @dfn{GNU},
1077 the portable operating system from the @dfn{Free Software
1078 Foundation, Inc.}. This restricts our attention to certain kinds of
1079 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1080 once this assumption is granted examples and definitions need less
1083 @command{@value{AS}} is part of a team of programs that turn a high-level
1084 human-readable series of instructions into a low-level
1085 computer-readable series of instructions. Different versions of
1086 @command{@value{AS}} are used for different kinds of computer.
1089 @c There used to be a section "Terminology" here, which defined
1090 @c "contents", "byte", "word", and "long". Defining "word" to any
1091 @c particular size is confusing when the .word directive may generate 16
1092 @c bits on one machine and 32 bits on another; in general, for the user
1093 @c version of this manual, none of these terms seem essential to define.
1094 @c They were used very little even in the former draft of the manual;
1095 @c this draft makes an effort to avoid them (except in names of
1099 @section The GNU Assembler
1101 @c man begin DESCRIPTION
1103 @sc{gnu} @command{as} is really a family of assemblers.
1105 This manual describes @command{@value{AS}}, a member of that family which is
1106 configured for the @value{TARGET} architectures.
1108 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1109 should find a fairly similar environment when you use it on another
1110 architecture. Each version has much in common with the others,
1111 including object file formats, most assembler directives (often called
1112 @dfn{pseudo-ops}) and assembler syntax.@refill
1114 @cindex purpose of @sc{gnu} assembler
1115 @command{@value{AS}} is primarily intended to assemble the output of the
1116 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1117 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1118 assemble correctly everything that other assemblers for the same
1119 machine would assemble.
1121 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1124 @c This remark should appear in generic version of manual; assumption
1125 @c here is that generic version sets M680x0.
1126 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1127 assembler for the same architecture; for example, we know of several
1128 incompatible versions of 680x0 assembly language syntax.
1133 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1134 program in one pass of the source file. This has a subtle impact on the
1135 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1137 @node Object Formats
1138 @section Object File Formats
1140 @cindex object file format
1141 The @sc{gnu} assembler can be configured to produce several alternative
1142 object file formats. For the most part, this does not affect how you
1143 write assembly language programs; but directives for debugging symbols
1144 are typically different in different file formats. @xref{Symbol
1145 Attributes,,Symbol Attributes}.
1148 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1149 @value{OBJ-NAME} format object files.
1151 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1153 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1154 @code{a.out} or COFF format object files.
1157 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1158 @code{b.out} or COFF format object files.
1161 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1162 SOM or ELF format object files.
1167 @section Command Line
1169 @cindex command line conventions
1171 After the program name @command{@value{AS}}, the command line may contain
1172 options and file names. Options may appear in any order, and may be
1173 before, after, or between file names. The order of file names is
1176 @cindex standard input, as input file
1178 @file{--} (two hyphens) by itself names the standard input file
1179 explicitly, as one of the files for @command{@value{AS}} to assemble.
1181 @cindex options, command line
1182 Except for @samp{--} any command line argument that begins with a
1183 hyphen (@samp{-}) is an option. Each option changes the behavior of
1184 @command{@value{AS}}. No option changes the way another option works. An
1185 option is a @samp{-} followed by one or more letters; the case of
1186 the letter is important. All options are optional.
1188 Some options expect exactly one file name to follow them. The file
1189 name may either immediately follow the option's letter (compatible
1190 with older assemblers) or it may be the next command argument (@sc{gnu}
1191 standard). These two command lines are equivalent:
1194 @value{AS} -o my-object-file.o mumble.s
1195 @value{AS} -omy-object-file.o mumble.s
1199 @section Input Files
1202 @cindex source program
1203 @cindex files, input
1204 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1205 describe the program input to one run of @command{@value{AS}}. The program may
1206 be in one or more files; how the source is partitioned into files
1207 doesn't change the meaning of the source.
1209 @c I added "con" prefix to "catenation" just to prove I can overcome my
1210 @c APL training... doc@cygnus.com
1211 The source program is a concatenation of the text in all the files, in the
1214 @c man begin DESCRIPTION
1215 Each time you run @command{@value{AS}} it assembles exactly one source
1216 program. The source program is made up of one or more files.
1217 (The standard input is also a file.)
1219 You give @command{@value{AS}} a command line that has zero or more input file
1220 names. The input files are read (from left file name to right). A
1221 command line argument (in any position) that has no special meaning
1222 is taken to be an input file name.
1224 If you give @command{@value{AS}} no file names it attempts to read one input file
1225 from the @command{@value{AS}} standard input, which is normally your terminal. You
1226 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1229 Use @samp{--} if you need to explicitly name the standard input file
1230 in your command line.
1232 If the source is empty, @command{@value{AS}} produces a small, empty object
1237 @subheading Filenames and Line-numbers
1239 @cindex input file linenumbers
1240 @cindex line numbers, in input files
1241 There are two ways of locating a line in the input file (or files) and
1242 either may be used in reporting error messages. One way refers to a line
1243 number in a physical file; the other refers to a line number in a
1244 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1246 @dfn{Physical files} are those files named in the command line given
1247 to @command{@value{AS}}.
1249 @dfn{Logical files} are simply names declared explicitly by assembler
1250 directives; they bear no relation to physical files. Logical file names help
1251 error messages reflect the original source file, when @command{@value{AS}} source
1252 is itself synthesized from other files. @command{@value{AS}} understands the
1253 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1254 @ref{File,,@code{.file}}.
1257 @section Output (Object) File
1263 Every time you run @command{@value{AS}} it produces an output file, which is
1264 your assembly language program translated into numbers. This file
1265 is the object file. Its default name is
1273 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1275 You can give it another name by using the @option{-o} option. Conventionally,
1276 object file names end with @file{.o}. The default name is used for historical
1277 reasons: older assemblers were capable of assembling self-contained programs
1278 directly into a runnable program. (For some formats, this isn't currently
1279 possible, but it can be done for the @code{a.out} format.)
1283 The object file is meant for input to the linker @code{@value{LD}}. It contains
1284 assembled program code, information to help @code{@value{LD}} integrate
1285 the assembled program into a runnable file, and (optionally) symbolic
1286 information for the debugger.
1288 @c link above to some info file(s) like the description of a.out.
1289 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1292 @section Error and Warning Messages
1294 @c man begin DESCRIPTION
1296 @cindex error messages
1297 @cindex warning messages
1298 @cindex messages from assembler
1299 @command{@value{AS}} may write warnings and error messages to the standard error
1300 file (usually your terminal). This should not happen when a compiler
1301 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1302 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1303 grave problem that stops the assembly.
1307 @cindex format of warning messages
1308 Warning messages have the format
1311 file_name:@b{NNN}:Warning Message Text
1315 @cindex line numbers, in warnings/errors
1316 (where @b{NNN} is a line number). If a logical file name has been given
1317 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1318 the current input file is used. If a logical line number was given
1320 (@pxref{Line,,@code{.line}})
1324 (@pxref{Line,,@code{.line}})
1327 (@pxref{Ln,,@code{.ln}})
1330 then it is used to calculate the number printed,
1331 otherwise the actual line in the current source file is printed. The
1332 message text is intended to be self explanatory (in the grand Unix
1335 @cindex format of error messages
1336 Error messages have the format
1338 file_name:@b{NNN}:FATAL:Error Message Text
1340 The file name and line number are derived as for warning
1341 messages. The actual message text may be rather less explanatory
1342 because many of them aren't supposed to happen.
1345 @chapter Command-Line Options
1347 @cindex options, all versions of assembler
1348 This chapter describes command-line options available in @emph{all}
1349 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1351 to the @value{TARGET}.
1354 to particular machine architectures.
1357 @c man begin DESCRIPTION
1359 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1360 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1361 The assembler arguments must be separated from each other (and the @samp{-Wa})
1362 by commas. For example:
1365 gcc -c -g -O -Wa,-alh,-L file.c
1369 This passes two options to the assembler: @samp{-alh} (emit a listing to
1370 standard output with with high-level and assembly source) and @samp{-L} (retain
1371 local symbols in the symbol table).
1373 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1374 command-line options are automatically passed to the assembler by the compiler.
1375 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1376 precisely what options it passes to each compilation pass, including the
1382 * a:: -a[cdhlns] enable listings
1383 * D:: -D for compatibility
1384 * f:: -f to work faster
1385 * I:: -I for .include search path
1386 @ifclear DIFF-TBL-KLUGE
1387 * K:: -K for compatibility
1389 @ifset DIFF-TBL-KLUGE
1390 * K:: -K for difference tables
1393 * L:: -L to retain local labels
1394 * listing:: --listing-XXX to configure listing output
1395 * M:: -M or --mri to assemble in MRI compatibility mode
1396 * MD:: --MD for dependency tracking
1397 * o:: -o to name the object file
1398 * R:: -R to join data and text sections
1399 * statistics:: --statistics to see statistics about assembly
1400 * traditional-format:: --traditional-format for compatible output
1401 * v:: -v to announce version
1402 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1403 * Z:: -Z to make object file even after errors
1407 @section Enable Listings: @option{-a[cdhlns]}
1416 @cindex listings, enabling
1417 @cindex assembly listings, enabling
1419 These options enable listing output from the assembler. By itself,
1420 @samp{-a} requests high-level, assembly, and symbols listing.
1421 You can use other letters to select specific options for the list:
1422 @samp{-ah} requests a high-level language listing,
1423 @samp{-al} requests an output-program assembly listing, and
1424 @samp{-as} requests a symbol table listing.
1425 High-level listings require that a compiler debugging option like
1426 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1429 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1430 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1431 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1432 omitted from the listing.
1434 Use the @samp{-ad} option to omit debugging directives from the
1437 Once you have specified one of these options, you can further control
1438 listing output and its appearance using the directives @code{.list},
1439 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1441 The @samp{-an} option turns off all forms processing.
1442 If you do not request listing output with one of the @samp{-a} options, the
1443 listing-control directives have no effect.
1445 The letters after @samp{-a} may be combined into one option,
1446 @emph{e.g.}, @samp{-aln}.
1448 Note if the assembler source is coming from the standard input (eg because it
1449 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1450 is being used) then the listing will not contain any comments or preprocessor
1451 directives. This is because the listing code buffers input source lines from
1452 stdin only after they have been preprocessed by the assembler. This reduces
1453 memory usage and makes the code more efficient.
1456 @section @option{-D}
1459 This option has no effect whatsoever, but it is accepted to make it more
1460 likely that scripts written for other assemblers also work with
1461 @command{@value{AS}}.
1464 @section Work Faster: @option{-f}
1467 @cindex trusted compiler
1468 @cindex faster processing (@option{-f})
1469 @samp{-f} should only be used when assembling programs written by a
1470 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1471 and comment preprocessing on
1472 the input file(s) before assembling them. @xref{Preprocessing,
1476 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1477 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1482 @section @code{.include} search path: @option{-I} @var{path}
1484 @kindex -I @var{path}
1485 @cindex paths for @code{.include}
1486 @cindex search path for @code{.include}
1487 @cindex @code{include} directive search path
1488 Use this option to add a @var{path} to the list of directories
1489 @command{@value{AS}} searches for files specified in @code{.include}
1490 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1491 many times as necessary to include a variety of paths. The current
1492 working directory is always searched first; after that, @command{@value{AS}}
1493 searches any @samp{-I} directories in the same order as they were
1494 specified (left to right) on the command line.
1497 @section Difference Tables: @option{-K}
1500 @ifclear DIFF-TBL-KLUGE
1501 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1502 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1503 where it can be used to warn when the assembler alters the machine code
1504 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1505 family does not have the addressing limitations that sometimes lead to this
1506 alteration on other platforms.
1509 @ifset DIFF-TBL-KLUGE
1510 @cindex difference tables, warning
1511 @cindex warning for altered difference tables
1512 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1513 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1514 You can use the @samp{-K} option if you want a warning issued when this
1519 @section Include Local Labels: @option{-L}
1522 @cindex local labels, retaining in output
1523 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1524 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1525 debugging, because they are intended for the use of programs (like
1526 compilers) that compose assembler programs, not for your notice.
1527 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1528 normally debug with them.
1530 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1531 in the object file. Usually if you do this you also tell the linker
1532 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1534 By default, a local label is any label beginning with @samp{L}, but each
1535 target is allowed to redefine the local label prefix.
1537 On the HPPA local labels begin with @samp{L$}.
1541 @section Configuring listing output: @option{--listing}
1543 The listing feature of the assembler can be enabled via the command line switch
1544 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1545 hex dump of the corresponding locations in the output object file, and displays
1546 them as a listing file. The format of this listing can be controlled by pseudo
1547 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1548 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1551 @item --listing-lhs-width=@samp{number}
1552 @kindex --listing-lhs-width
1553 @cindex Width of first line disassembly output
1554 Sets the maximum width, in words, of the first line of the hex byte dump. This
1555 dump appears on the left hand side of the listing output.
1557 @item --listing-lhs-width2=@samp{number}
1558 @kindex --listing-lhs-width2
1559 @cindex Width of continuation lines of disassembly output
1560 Sets the maximum width, in words, of any further lines of the hex byte dump for
1561 a given inut source line. If this value is not specified, it defaults to being
1562 the same as the value specified for @samp{--listing-lhs-width}. If neither
1563 switch is used the default is to one.
1565 @item --listing-rhs-width=@samp{number}
1566 @kindex --listing-rhs-width
1567 @cindex Width of source line output
1568 Sets the maximum width, in characters, of the source line that is displayed
1569 alongside the hex dump. The default value for this parameter is 100. The
1570 source line is displayed on the right hand side of the listing output.
1572 @item --listing-cont-lines=@samp{number}
1573 @kindex --listing-cont-lines
1574 @cindex Maximum number of continuation lines
1575 Sets the maximum number of continuation lines of hex dump that will be
1576 displayed for a given single line of source input. The default value is 4.
1580 @section Assemble in MRI Compatibility Mode: @option{-M}
1583 @cindex MRI compatibility mode
1584 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1585 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1586 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1587 configured target) assembler from Microtec Research. The exact nature of the
1588 MRI syntax will not be documented here; see the MRI manuals for more
1589 information. Note in particular that the handling of macros and macro
1590 arguments is somewhat different. The purpose of this option is to permit
1591 assembling existing MRI assembler code using @command{@value{AS}}.
1593 The MRI compatibility is not complete. Certain operations of the MRI assembler
1594 depend upon its object file format, and can not be supported using other object
1595 file formats. Supporting these would require enhancing each object file format
1596 individually. These are:
1599 @item global symbols in common section
1601 The m68k MRI assembler supports common sections which are merged by the linker.
1602 Other object file formats do not support this. @command{@value{AS}} handles
1603 common sections by treating them as a single common symbol. It permits local
1604 symbols to be defined within a common section, but it can not support global
1605 symbols, since it has no way to describe them.
1607 @item complex relocations
1609 The MRI assemblers support relocations against a negated section address, and
1610 relocations which combine the start addresses of two or more sections. These
1611 are not support by other object file formats.
1613 @item @code{END} pseudo-op specifying start address
1615 The MRI @code{END} pseudo-op permits the specification of a start address.
1616 This is not supported by other object file formats. The start address may
1617 instead be specified using the @option{-e} option to the linker, or in a linker
1620 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1622 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1623 name to the output file. This is not supported by other object file formats.
1625 @item @code{ORG} pseudo-op
1627 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1628 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1629 which changes the location within the current section. Absolute sections are
1630 not supported by other object file formats. The address of a section may be
1631 assigned within a linker script.
1634 There are some other features of the MRI assembler which are not supported by
1635 @command{@value{AS}}, typically either because they are difficult or because they
1636 seem of little consequence. Some of these may be supported in future releases.
1640 @item EBCDIC strings
1642 EBCDIC strings are not supported.
1644 @item packed binary coded decimal
1646 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1647 and @code{DCB.P} pseudo-ops are not supported.
1649 @item @code{FEQU} pseudo-op
1651 The m68k @code{FEQU} pseudo-op is not supported.
1653 @item @code{NOOBJ} pseudo-op
1655 The m68k @code{NOOBJ} pseudo-op is not supported.
1657 @item @code{OPT} branch control options
1659 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1660 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1661 relaxes all branches, whether forward or backward, to an appropriate size, so
1662 these options serve no purpose.
1664 @item @code{OPT} list control options
1666 The following m68k @code{OPT} list control options are ignored: @code{C},
1667 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1668 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1670 @item other @code{OPT} options
1672 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1673 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1675 @item @code{OPT} @code{D} option is default
1677 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1678 @code{OPT NOD} may be used to turn it off.
1680 @item @code{XREF} pseudo-op.
1682 The m68k @code{XREF} pseudo-op is ignored.
1684 @item @code{.debug} pseudo-op
1686 The i960 @code{.debug} pseudo-op is not supported.
1688 @item @code{.extended} pseudo-op
1690 The i960 @code{.extended} pseudo-op is not supported.
1692 @item @code{.list} pseudo-op.
1694 The various options of the i960 @code{.list} pseudo-op are not supported.
1696 @item @code{.optimize} pseudo-op
1698 The i960 @code{.optimize} pseudo-op is not supported.
1700 @item @code{.output} pseudo-op
1702 The i960 @code{.output} pseudo-op is not supported.
1704 @item @code{.setreal} pseudo-op
1706 The i960 @code{.setreal} pseudo-op is not supported.
1711 @section Dependency tracking: @option{--MD}
1714 @cindex dependency tracking
1717 @command{@value{AS}} can generate a dependency file for the file it creates. This
1718 file consists of a single rule suitable for @code{make} describing the
1719 dependencies of the main source file.
1721 The rule is written to the file named in its argument.
1723 This feature is used in the automatic updating of makefiles.
1726 @section Name the Object File: @option{-o}
1729 @cindex naming object file
1730 @cindex object file name
1731 There is always one object file output when you run @command{@value{AS}}. By
1732 default it has the name
1735 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1749 You use this option (which takes exactly one filename) to give the
1750 object file a different name.
1752 Whatever the object file is called, @command{@value{AS}} overwrites any
1753 existing file of the same name.
1756 @section Join Data and Text Sections: @option{-R}
1759 @cindex data and text sections, joining
1760 @cindex text and data sections, joining
1761 @cindex joining text and data sections
1762 @cindex merging text and data sections
1763 @option{-R} tells @command{@value{AS}} to write the object file as if all
1764 data-section data lives in the text section. This is only done at
1765 the very last moment: your binary data are the same, but data
1766 section parts are relocated differently. The data section part of
1767 your object file is zero bytes long because all its bytes are
1768 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1770 When you specify @option{-R} it would be possible to generate shorter
1771 address displacements (because we do not have to cross between text and
1772 data section). We refrain from doing this simply for compatibility with
1773 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1776 When @command{@value{AS}} is configured for COFF output,
1777 this option is only useful if you use sections named @samp{.text} and
1782 @option{-R} is not supported for any of the HPPA targets. Using
1783 @option{-R} generates a warning from @command{@value{AS}}.
1787 @section Display Assembly Statistics: @option{--statistics}
1789 @kindex --statistics
1790 @cindex statistics, about assembly
1791 @cindex time, total for assembly
1792 @cindex space used, maximum for assembly
1793 Use @samp{--statistics} to display two statistics about the resources used by
1794 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1795 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1798 @node traditional-format
1799 @section Compatible output: @option{--traditional-format}
1801 @kindex --traditional-format
1802 For some targets, the output of @command{@value{AS}} is different in some ways
1803 from the output of some existing assembler. This switch requests
1804 @command{@value{AS}} to use the traditional format instead.
1806 For example, it disables the exception frame optimizations which
1807 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1810 @section Announce Version: @option{-v}
1814 @cindex assembler version
1815 @cindex version of assembler
1816 You can find out what version of as is running by including the
1817 option @samp{-v} (which you can also spell as @samp{-version}) on the
1821 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1823 @command{@value{AS}} should never give a warning or error message when
1824 assembling compiler output. But programs written by people often
1825 cause @command{@value{AS}} to give a warning that a particular assumption was
1826 made. All such warnings are directed to the standard error file.
1829 @kindex @samp{--no-warn}
1830 @cindex suppressing warnings
1831 @cindex warnings, suppressing
1832 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1833 This only affects the warning messages: it does not change any particular of
1834 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1837 @kindex @samp{--fatal-warnings}
1838 @cindex errors, caused by warnings
1839 @cindex warnings, causing error
1840 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1841 files that generate warnings to be in error.
1843 @kindex @samp{--warn}
1844 @cindex warnings, switching on
1845 You can switch these options off again by specifying @option{--warn}, which
1846 causes warnings to be output as usual.
1849 @section Generate Object File in Spite of Errors: @option{-Z}
1850 @cindex object file, after errors
1851 @cindex errors, continuing after
1852 After an error message, @command{@value{AS}} normally produces no output. If for
1853 some reason you are interested in object file output even after
1854 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1855 option. If there are any errors, @command{@value{AS}} continues anyways, and
1856 writes an object file after a final warning message of the form @samp{@var{n}
1857 errors, @var{m} warnings, generating bad object file.}
1862 @cindex machine-independent syntax
1863 @cindex syntax, machine-independent
1864 This chapter describes the machine-independent syntax allowed in a
1865 source file. @command{@value{AS}} syntax is similar to what many other
1866 assemblers use; it is inspired by the BSD 4.2
1871 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1875 * Preprocessing:: Preprocessing
1876 * Whitespace:: Whitespace
1877 * Comments:: Comments
1878 * Symbol Intro:: Symbols
1879 * Statements:: Statements
1880 * Constants:: Constants
1884 @section Preprocessing
1886 @cindex preprocessing
1887 The @command{@value{AS}} internal preprocessor:
1889 @cindex whitespace, removed by preprocessor
1891 adjusts and removes extra whitespace. It leaves one space or tab before
1892 the keywords on a line, and turns any other whitespace on the line into
1895 @cindex comments, removed by preprocessor
1897 removes all comments, replacing them with a single space, or an
1898 appropriate number of newlines.
1900 @cindex constants, converted by preprocessor
1902 converts character constants into the appropriate numeric values.
1905 It does not do macro processing, include file handling, or
1906 anything else you may get from your C compiler's preprocessor. You can
1907 do include file processing with the @code{.include} directive
1908 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1909 to get other ``CPP'' style preprocessing, by giving the input file a
1910 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1911 Output, gcc.info, Using GNU CC}.
1913 Excess whitespace, comments, and character constants
1914 cannot be used in the portions of the input text that are not
1917 @cindex turning preprocessing on and off
1918 @cindex preprocessing, turning on and off
1921 If the first line of an input file is @code{#NO_APP} or if you use the
1922 @samp{-f} option, whitespace and comments are not removed from the input file.
1923 Within an input file, you can ask for whitespace and comment removal in
1924 specific portions of the by putting a line that says @code{#APP} before the
1925 text that may contain whitespace or comments, and putting a line that says
1926 @code{#NO_APP} after this text. This feature is mainly intend to support
1927 @code{asm} statements in compilers whose output is otherwise free of comments
1934 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1935 Whitespace is used to separate symbols, and to make programs neater for
1936 people to read. Unless within character constants
1937 (@pxref{Characters,,Character Constants}), any whitespace means the same
1938 as exactly one space.
1944 There are two ways of rendering comments to @command{@value{AS}}. In both
1945 cases the comment is equivalent to one space.
1947 Anything from @samp{/*} through the next @samp{*/} is a comment.
1948 This means you may not nest these comments.
1952 The only way to include a newline ('\n') in a comment
1953 is to use this sort of comment.
1956 /* This sort of comment does not nest. */
1959 @cindex line comment character
1960 Anything from the @dfn{line comment} character to the next newline
1961 is considered a comment and is ignored. The line comment character is
1963 @samp{;} for the AMD 29K family;
1966 @samp{;} on the ARC;
1969 @samp{@@} on the ARM;
1972 @samp{;} for the H8/300 family;
1975 @samp{!} for the H8/500 family;
1978 @samp{;} for the HPPA;
1981 @samp{#} on the i386 and x86-64;
1984 @samp{#} on the i960;
1987 @samp{;} for the PDP-11;
1990 @samp{;} for picoJava;
1993 @samp{;} for Motorola PowerPC;
1996 @samp{!} for the Hitachi SH;
1999 @samp{!} on the SPARC;
2002 @samp{#} on the m32r;
2005 @samp{|} on the 680x0;
2008 @samp{#} on the 68HC11 and 68HC12;
2011 @samp{;} on the M880x0;
2014 @samp{#} on the Vax;
2017 @samp{!} for the Z8000;
2020 @samp{#} on the V850;
2022 see @ref{Machine Dependencies}. @refill
2023 @c FIXME What about i860?
2026 On some machines there are two different line comment characters. One
2027 character only begins a comment if it is the first non-whitespace character on
2028 a line, while the other always begins a comment.
2032 The V850 assembler also supports a double dash as starting a comment that
2033 extends to the end of the line.
2039 @cindex lines starting with @code{#}
2040 @cindex logical line numbers
2041 To be compatible with past assemblers, lines that begin with @samp{#} have a
2042 special interpretation. Following the @samp{#} should be an absolute
2043 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2044 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2045 new logical file name. The rest of the line, if any, should be whitespace.
2047 If the first non-whitespace characters on the line are not numeric,
2048 the line is ignored. (Just like a comment.)
2051 # This is an ordinary comment.
2052 # 42-6 "new_file_name" # New logical file name
2053 # This is logical line # 36.
2055 This feature is deprecated, and may disappear from future versions
2056 of @command{@value{AS}}.
2061 @cindex characters used in symbols
2062 @ifclear SPECIAL-SYMS
2063 A @dfn{symbol} is one or more characters chosen from the set of all
2064 letters (both upper and lower case), digits and the three characters
2070 A @dfn{symbol} is one or more characters chosen from the set of all
2071 letters (both upper and lower case), digits and the three characters
2072 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2078 On most machines, you can also use @code{$} in symbol names; exceptions
2079 are noted in @ref{Machine Dependencies}.
2081 No symbol may begin with a digit. Case is significant.
2082 There is no length limit: all characters are significant. Symbols are
2083 delimited by characters not in that set, or by the beginning of a file
2084 (since the source program must end with a newline, the end of a file is
2085 not a possible symbol delimiter). @xref{Symbols}.
2086 @cindex length of symbols
2091 @cindex statements, structure of
2092 @cindex line separator character
2093 @cindex statement separator character
2095 @ifclear abnormal-separator
2096 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2097 semicolon (@samp{;}). The newline or semicolon is considered part of
2098 the preceding statement. Newlines and semicolons within character
2099 constants are an exception: they do not end statements.
2101 @ifset abnormal-separator
2103 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2104 sign (@samp{@@}). The newline or at sign is considered part of the
2105 preceding statement. Newlines and at signs within character constants
2106 are an exception: they do not end statements.
2109 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2110 point (@samp{!}). The newline or exclamation point is considered part of the
2111 preceding statement. Newlines and exclamation points within character
2112 constants are an exception: they do not end statements.
2115 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2116 H8/300) a dollar sign (@samp{$}); or (for the
2119 (@samp{;}). The newline or separator character is considered part of
2120 the preceding statement. Newlines and separators within character
2121 constants are an exception: they do not end statements.
2126 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2127 separator character. (The line separator is usually @samp{;}, unless
2128 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2129 newline or separator character is considered part of the preceding
2130 statement. Newlines and separators within character constants are an
2131 exception: they do not end statements.
2134 @cindex newline, required at file end
2135 @cindex EOF, newline must precede
2136 It is an error to end any statement with end-of-file: the last
2137 character of any input file should be a newline.@refill
2139 An empty statement is allowed, and may include whitespace. It is ignored.
2141 @cindex instructions and directives
2142 @cindex directives and instructions
2143 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2144 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2146 A statement begins with zero or more labels, optionally followed by a
2147 key symbol which determines what kind of statement it is. The key
2148 symbol determines the syntax of the rest of the statement. If the
2149 symbol begins with a dot @samp{.} then the statement is an assembler
2150 directive: typically valid for any computer. If the symbol begins with
2151 a letter the statement is an assembly language @dfn{instruction}: it
2152 assembles into a machine language instruction.
2154 Different versions of @command{@value{AS}} for different computers
2155 recognize different instructions. In fact, the same symbol may
2156 represent a different instruction in a different computer's assembly
2160 @cindex @code{:} (label)
2161 @cindex label (@code{:})
2162 A label is a symbol immediately followed by a colon (@code{:}).
2163 Whitespace before a label or after a colon is permitted, but you may not
2164 have whitespace between a label's symbol and its colon. @xref{Labels}.
2167 For HPPA targets, labels need not be immediately followed by a colon, but
2168 the definition of a label must begin in column zero. This also implies that
2169 only one label may be defined on each line.
2173 label: .directive followed by something
2174 another_label: # This is an empty statement.
2175 instruction operand_1, operand_2, @dots{}
2182 A constant is a number, written so that its value is known by
2183 inspection, without knowing any context. Like this:
2186 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2187 .ascii "Ring the bell\7" # A string constant.
2188 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2189 .float 0f-314159265358979323846264338327\
2190 95028841971.693993751E-40 # - pi, a flonum.
2195 * Characters:: Character Constants
2196 * Numbers:: Number Constants
2200 @subsection Character Constants
2202 @cindex character constants
2203 @cindex constants, character
2204 There are two kinds of character constants. A @dfn{character} stands
2205 for one character in one byte and its value may be used in
2206 numeric expressions. String constants (properly called string
2207 @emph{literals}) are potentially many bytes and their values may not be
2208 used in arithmetic expressions.
2212 * Chars:: Characters
2216 @subsubsection Strings
2218 @cindex string constants
2219 @cindex constants, string
2220 A @dfn{string} is written between double-quotes. It may contain
2221 double-quotes or null characters. The way to get special characters
2222 into a string is to @dfn{escape} these characters: precede them with
2223 a backslash @samp{\} character. For example @samp{\\} represents
2224 one backslash: the first @code{\} is an escape which tells
2225 @command{@value{AS}} to interpret the second character literally as a backslash
2226 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2227 escape character). The complete list of escapes follows.
2229 @cindex escape codes, character
2230 @cindex character escape codes
2233 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2235 @cindex @code{\b} (backspace character)
2236 @cindex backspace (@code{\b})
2238 Mnemonic for backspace; for ASCII this is octal code 010.
2241 @c Mnemonic for EOText; for ASCII this is octal code 004.
2243 @cindex @code{\f} (formfeed character)
2244 @cindex formfeed (@code{\f})
2246 Mnemonic for FormFeed; for ASCII this is octal code 014.
2248 @cindex @code{\n} (newline character)
2249 @cindex newline (@code{\n})
2251 Mnemonic for newline; for ASCII this is octal code 012.
2254 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2256 @cindex @code{\r} (carriage return character)
2257 @cindex carriage return (@code{\r})
2259 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2262 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2263 @c other assemblers.
2265 @cindex @code{\t} (tab)
2266 @cindex tab (@code{\t})
2268 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2271 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2272 @c @item \x @var{digit} @var{digit} @var{digit}
2273 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2275 @cindex @code{\@var{ddd}} (octal character code)
2276 @cindex octal character code (@code{\@var{ddd}})
2277 @item \ @var{digit} @var{digit} @var{digit}
2278 An octal character code. The numeric code is 3 octal digits.
2279 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2280 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2282 @cindex @code{\@var{xd...}} (hex character code)
2283 @cindex hex character code (@code{\@var{xd...}})
2284 @item \@code{x} @var{hex-digits...}
2285 A hex character code. All trailing hex digits are combined. Either upper or
2286 lower case @code{x} works.
2288 @cindex @code{\\} (@samp{\} character)
2289 @cindex backslash (@code{\\})
2291 Represents one @samp{\} character.
2294 @c Represents one @samp{'} (accent acute) character.
2295 @c This is needed in single character literals
2296 @c (@xref{Characters,,Character Constants}.) to represent
2299 @cindex @code{\"} (doublequote character)
2300 @cindex doublequote (@code{\"})
2302 Represents one @samp{"} character. Needed in strings to represent
2303 this character, because an unescaped @samp{"} would end the string.
2305 @item \ @var{anything-else}
2306 Any other character when escaped by @kbd{\} gives a warning, but
2307 assembles as if the @samp{\} was not present. The idea is that if
2308 you used an escape sequence you clearly didn't want the literal
2309 interpretation of the following character. However @command{@value{AS}} has no
2310 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2311 code and warns you of the fact.
2314 Which characters are escapable, and what those escapes represent,
2315 varies widely among assemblers. The current set is what we think
2316 the BSD 4.2 assembler recognizes, and is a subset of what most C
2317 compilers recognize. If you are in doubt, do not use an escape
2321 @subsubsection Characters
2323 @cindex single character constant
2324 @cindex character, single
2325 @cindex constant, single character
2326 A single character may be written as a single quote immediately
2327 followed by that character. The same escapes apply to characters as
2328 to strings. So if you want to write the character backslash, you
2329 must write @kbd{'\\} where the first @code{\} escapes the second
2330 @code{\}. As you can see, the quote is an acute accent, not a
2331 grave accent. A newline
2333 @ifclear abnormal-separator
2334 (or semicolon @samp{;})
2336 @ifset abnormal-separator
2338 (or at sign @samp{@@})
2341 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2347 immediately following an acute accent is taken as a literal character
2348 and does not count as the end of a statement. The value of a character
2349 constant in a numeric expression is the machine's byte-wide code for
2350 that character. @command{@value{AS}} assumes your character code is ASCII:
2351 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2354 @subsection Number Constants
2356 @cindex constants, number
2357 @cindex number constants
2358 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2359 are stored in the target machine. @emph{Integers} are numbers that
2360 would fit into an @code{int} in the C language. @emph{Bignums} are
2361 integers, but they are stored in more than 32 bits. @emph{Flonums}
2362 are floating point numbers, described below.
2365 * Integers:: Integers
2370 * Bit Fields:: Bit Fields
2376 @subsubsection Integers
2378 @cindex constants, integer
2380 @cindex binary integers
2381 @cindex integers, binary
2382 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2383 the binary digits @samp{01}.
2385 @cindex octal integers
2386 @cindex integers, octal
2387 An octal integer is @samp{0} followed by zero or more of the octal
2388 digits (@samp{01234567}).
2390 @cindex decimal integers
2391 @cindex integers, decimal
2392 A decimal integer starts with a non-zero digit followed by zero or
2393 more digits (@samp{0123456789}).
2395 @cindex hexadecimal integers
2396 @cindex integers, hexadecimal
2397 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2398 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2400 Integers have the usual values. To denote a negative integer, use
2401 the prefix operator @samp{-} discussed under expressions
2402 (@pxref{Prefix Ops,,Prefix Operators}).
2405 @subsubsection Bignums
2408 @cindex constants, bignum
2409 A @dfn{bignum} has the same syntax and semantics as an integer
2410 except that the number (or its negative) takes more than 32 bits to
2411 represent in binary. The distinction is made because in some places
2412 integers are permitted while bignums are not.
2415 @subsubsection Flonums
2417 @cindex floating point numbers
2418 @cindex constants, floating point
2420 @cindex precision, floating point
2421 A @dfn{flonum} represents a floating point number. The translation is
2422 indirect: a decimal floating point number from the text is converted by
2423 @command{@value{AS}} to a generic binary floating point number of more than
2424 sufficient precision. This generic floating point number is converted
2425 to a particular computer's floating point format (or formats) by a
2426 portion of @command{@value{AS}} specialized to that computer.
2428 A flonum is written by writing (in order)
2433 (@samp{0} is optional on the HPPA.)
2437 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2439 @kbd{e} is recommended. Case is not important.
2441 @c FIXME: verify if flonum syntax really this vague for most cases
2442 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2443 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2446 On the H8/300, H8/500,
2448 and AMD 29K architectures, the letter must be
2449 one of the letters @samp{DFPRSX} (in upper or lower case).
2451 On the ARC, the letter must be one of the letters @samp{DFRS}
2452 (in upper or lower case).
2454 On the Intel 960 architecture, the letter must be
2455 one of the letters @samp{DFT} (in upper or lower case).
2457 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2461 One of the letters @samp{DFPRSX} (in upper or lower case).
2464 One of the letters @samp{DFRS} (in upper or lower case).
2467 One of the letters @samp{DFPRSX} (in upper or lower case).
2470 The letter @samp{E} (upper case only).
2473 One of the letters @samp{DFT} (in upper or lower case).
2478 An optional sign: either @samp{+} or @samp{-}.
2481 An optional @dfn{integer part}: zero or more decimal digits.
2484 An optional @dfn{fractional part}: @samp{.} followed by zero
2485 or more decimal digits.
2488 An optional exponent, consisting of:
2492 An @samp{E} or @samp{e}.
2493 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2494 @c principle this can perfectly well be different on different targets.
2496 Optional sign: either @samp{+} or @samp{-}.
2498 One or more decimal digits.
2503 At least one of the integer part or the fractional part must be
2504 present. The floating point number has the usual base-10 value.
2506 @command{@value{AS}} does all processing using integers. Flonums are computed
2507 independently of any floating point hardware in the computer running
2508 @command{@value{AS}}.
2512 @c Bit fields are written as a general facility but are also controlled
2513 @c by a conditional-compilation flag---which is as of now (21mar91)
2514 @c turned on only by the i960 config of GAS.
2516 @subsubsection Bit Fields
2519 @cindex constants, bit field
2520 You can also define numeric constants as @dfn{bit fields}.
2521 specify two numbers separated by a colon---
2523 @var{mask}:@var{value}
2526 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2529 The resulting number is then packed
2531 @c this conditional paren in case bit fields turned on elsewhere than 960
2532 (in host-dependent byte order)
2534 into a field whose width depends on which assembler directive has the
2535 bit-field as its argument. Overflow (a result from the bitwise and
2536 requiring more binary digits to represent) is not an error; instead,
2537 more constants are generated, of the specified width, beginning with the
2538 least significant digits.@refill
2540 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2541 @code{.short}, and @code{.word} accept bit-field arguments.
2546 @chapter Sections and Relocation
2551 * Secs Background:: Background
2552 * Ld Sections:: Linker Sections
2553 * As Sections:: Assembler Internal Sections
2554 * Sub-Sections:: Sub-Sections
2558 @node Secs Background
2561 Roughly, a section is a range of addresses, with no gaps; all data
2562 ``in'' those addresses is treated the same for some particular purpose.
2563 For example there may be a ``read only'' section.
2565 @cindex linker, and assembler
2566 @cindex assembler, and linker
2567 The linker @code{@value{LD}} reads many object files (partial programs) and
2568 combines their contents to form a runnable program. When @command{@value{AS}}
2569 emits an object file, the partial program is assumed to start at address 0.
2570 @code{@value{LD}} assigns the final addresses for the partial program, so that
2571 different partial programs do not overlap. This is actually an
2572 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2575 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2576 addresses. These blocks slide to their run-time addresses as rigid
2577 units; their length does not change and neither does the order of bytes
2578 within them. Such a rigid unit is called a @emph{section}. Assigning
2579 run-time addresses to sections is called @dfn{relocation}. It includes
2580 the task of adjusting mentions of object-file addresses so they refer to
2581 the proper run-time addresses.
2583 For the H8/300 and H8/500,
2584 and for the Hitachi SH,
2585 @command{@value{AS}} pads sections if needed to
2586 ensure they end on a word (sixteen bit) boundary.
2589 @cindex standard assembler sections
2590 An object file written by @command{@value{AS}} has at least three sections, any
2591 of which may be empty. These are named @dfn{text}, @dfn{data} and
2596 When it generates COFF output,
2598 @command{@value{AS}} can also generate whatever other named sections you specify
2599 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2600 If you do not use any directives that place output in the @samp{.text}
2601 or @samp{.data} sections, these sections still exist, but are empty.
2606 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2608 @command{@value{AS}} can also generate whatever other named sections you
2609 specify using the @samp{.space} and @samp{.subspace} directives. See
2610 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2611 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2612 assembler directives.
2615 Additionally, @command{@value{AS}} uses different names for the standard
2616 text, data, and bss sections when generating SOM output. Program text
2617 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2618 BSS into @samp{$BSS$}.
2622 Within the object file, the text section starts at address @code{0}, the
2623 data section follows, and the bss section follows the data section.
2626 When generating either SOM or ELF output files on the HPPA, the text
2627 section starts at address @code{0}, the data section at address
2628 @code{0x4000000}, and the bss section follows the data section.
2631 To let @code{@value{LD}} know which data changes when the sections are
2632 relocated, and how to change that data, @command{@value{AS}} also writes to the
2633 object file details of the relocation needed. To perform relocation
2634 @code{@value{LD}} must know, each time an address in the object
2638 Where in the object file is the beginning of this reference to
2641 How long (in bytes) is this reference?
2643 Which section does the address refer to? What is the numeric value of
2645 (@var{address}) @minus{} (@var{start-address of section})?
2648 Is the reference to an address ``Program-Counter relative''?
2651 @cindex addresses, format of
2652 @cindex section-relative addressing
2653 In fact, every address @command{@value{AS}} ever uses is expressed as
2655 (@var{section}) + (@var{offset into section})
2658 Further, most expressions @command{@value{AS}} computes have this section-relative
2661 (For some object formats, such as SOM for the HPPA, some expressions are
2662 symbol-relative instead.)
2665 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2666 @var{N} into section @var{secname}.''
2668 Apart from text, data and bss sections you need to know about the
2669 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2670 addresses in the absolute section remain unchanged. For example, address
2671 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2672 @code{@value{LD}}. Although the linker never arranges two partial programs'
2673 data sections with overlapping addresses after linking, @emph{by definition}
2674 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2675 part of a program is always the same address when the program is running as
2676 address @code{@{absolute@ 239@}} in any other part of the program.
2678 The idea of sections is extended to the @dfn{undefined} section. Any
2679 address whose section is unknown at assembly time is by definition
2680 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2681 Since numbers are always defined, the only way to generate an undefined
2682 address is to mention an undefined symbol. A reference to a named
2683 common block would be such a symbol: its value is unknown at assembly
2684 time so it has section @emph{undefined}.
2686 By analogy the word @emph{section} is used to describe groups of sections in
2687 the linked program. @code{@value{LD}} puts all partial programs' text
2688 sections in contiguous addresses in the linked program. It is
2689 customary to refer to the @emph{text section} of a program, meaning all
2690 the addresses of all partial programs' text sections. Likewise for
2691 data and bss sections.
2693 Some sections are manipulated by @code{@value{LD}}; others are invented for
2694 use of @command{@value{AS}} and have no meaning except during assembly.
2697 @section Linker Sections
2698 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2703 @cindex named sections
2704 @cindex sections, named
2705 @item named sections
2708 @cindex text section
2709 @cindex data section
2713 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2714 separate but equal sections. Anything you can say of one section is
2717 When the program is running, however, it is
2718 customary for the text section to be unalterable. The
2719 text section is often shared among processes: it contains
2720 instructions, constants and the like. The data section of a running
2721 program is usually alterable: for example, C variables would be stored
2722 in the data section.
2727 This section contains zeroed bytes when your program begins running. It
2728 is used to hold uninitialized variables or common storage. The length of
2729 each partial program's bss section is important, but because it starts
2730 out containing zeroed bytes there is no need to store explicit zero
2731 bytes in the object file. The bss section was invented to eliminate
2732 those explicit zeros from object files.
2734 @cindex absolute section
2735 @item absolute section
2736 Address 0 of this section is always ``relocated'' to runtime address 0.
2737 This is useful if you want to refer to an address that @code{@value{LD}} must
2738 not change when relocating. In this sense we speak of absolute
2739 addresses being ``unrelocatable'': they do not change during relocation.
2741 @cindex undefined section
2742 @item undefined section
2743 This ``section'' is a catch-all for address references to objects not in
2744 the preceding sections.
2745 @c FIXME: ref to some other doc on obj-file formats could go here.
2748 @cindex relocation example
2749 An idealized example of three relocatable sections follows.
2751 The example uses the traditional section names @samp{.text} and @samp{.data}.
2753 Memory addresses are on the horizontal axis.
2757 @c END TEXI2ROFF-KILL
2760 partial program # 1: |ttttt|dddd|00|
2767 partial program # 2: |TTT|DDD|000|
2770 +--+---+-----+--+----+---+-----+~~
2771 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2772 +--+---+-----+--+----+---+-----+~~
2774 addresses: 0 @dots{}
2781 \line{\it Partial program \#1: \hfil}
2782 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2783 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2785 \line{\it Partial program \#2: \hfil}
2786 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2787 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2789 \line{\it linked program: \hfil}
2790 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2791 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2792 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2793 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2795 \line{\it addresses: \hfil}
2799 @c END TEXI2ROFF-KILL
2802 @section Assembler Internal Sections
2804 @cindex internal assembler sections
2805 @cindex sections in messages, internal
2806 These sections are meant only for the internal use of @command{@value{AS}}. They
2807 have no meaning at run-time. You do not really need to know about these
2808 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2809 warning messages, so it might be helpful to have an idea of their
2810 meanings to @command{@value{AS}}. These sections are used to permit the
2811 value of every expression in your assembly language program to be a
2812 section-relative address.
2815 @cindex assembler internal logic error
2816 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2817 An internal assembler logic error has been found. This means there is a
2818 bug in the assembler.
2820 @cindex expr (internal section)
2822 The assembler stores complex expression internally as combinations of
2823 symbols. When it needs to represent an expression as a symbol, it puts
2824 it in the expr section.
2826 @c FIXME item transfer[t] vector preload
2827 @c FIXME item transfer[t] vector postload
2828 @c FIXME item register
2832 @section Sub-Sections
2834 @cindex numbered subsections
2835 @cindex grouping data
2841 fall into two sections: text and data.
2843 You may have separate groups of
2845 data in named sections
2849 data in named sections
2855 that you want to end up near to each other in the object file, even though they
2856 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2857 use @dfn{subsections} for this purpose. Within each section, there can be
2858 numbered subsections with values from 0 to 8192. Objects assembled into the
2859 same subsection go into the object file together with other objects in the same
2860 subsection. For example, a compiler might want to store constants in the text
2861 section, but might not want to have them interspersed with the program being
2862 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2863 section of code being output, and a @samp{.text 1} before each group of
2864 constants being output.
2866 Subsections are optional. If you do not use subsections, everything
2867 goes in subsection number zero.
2870 Each subsection is zero-padded up to a multiple of four bytes.
2871 (Subsections may be padded a different amount on different flavors
2872 of @command{@value{AS}}.)
2876 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2877 boundary (two bytes).
2878 The same is true on the Hitachi SH.
2881 @c FIXME section padding (alignment)?
2882 @c Rich Pixley says padding here depends on target obj code format; that
2883 @c doesn't seem particularly useful to say without further elaboration,
2884 @c so for now I say nothing about it. If this is a generic BFD issue,
2885 @c these paragraphs might need to vanish from this manual, and be
2886 @c discussed in BFD chapter of binutils (or some such).
2889 On the AMD 29K family, no particular padding is added to section or
2890 subsection sizes; @value{AS} forces no alignment on this platform.
2894 Subsections appear in your object file in numeric order, lowest numbered
2895 to highest. (All this to be compatible with other people's assemblers.)
2896 The object file contains no representation of subsections; @code{@value{LD}} and
2897 other programs that manipulate object files see no trace of them.
2898 They just see all your text subsections as a text section, and all your
2899 data subsections as a data section.
2901 To specify which subsection you want subsequent statements assembled
2902 into, use a numeric argument to specify it, in a @samp{.text
2903 @var{expression}} or a @samp{.data @var{expression}} statement.
2906 When generating COFF output, you
2911 can also use an extra subsection
2912 argument with arbitrary named sections: @samp{.section @var{name},
2915 @var{Expression} should be an absolute expression.
2916 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2917 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2918 begins in @code{text 0}. For instance:
2920 .text 0 # The default subsection is text 0 anyway.
2921 .ascii "This lives in the first text subsection. *"
2923 .ascii "But this lives in the second text subsection."
2925 .ascii "This lives in the data section,"
2926 .ascii "in the first data subsection."
2928 .ascii "This lives in the first text section,"
2929 .ascii "immediately following the asterisk (*)."
2932 Each section has a @dfn{location counter} incremented by one for every byte
2933 assembled into that section. Because subsections are merely a convenience
2934 restricted to @command{@value{AS}} there is no concept of a subsection location
2935 counter. There is no way to directly manipulate a location counter---but the
2936 @code{.align} directive changes it, and any label definition captures its
2937 current value. The location counter of the section where statements are being
2938 assembled is said to be the @dfn{active} location counter.
2941 @section bss Section
2944 @cindex common variable storage
2945 The bss section is used for local common variable storage.
2946 You may allocate address space in the bss section, but you may
2947 not dictate data to load into it before your program executes. When
2948 your program starts running, all the contents of the bss
2949 section are zeroed bytes.
2951 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2952 @ref{Lcomm,,@code{.lcomm}}.
2954 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2955 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2958 When assembling for a target which supports multiple sections, such as ELF or
2959 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2960 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2961 section. Typically the section will only contain symbol definitions and
2962 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2969 Symbols are a central concept: the programmer uses symbols to name
2970 things, the linker uses symbols to link, and the debugger uses symbols
2974 @cindex debuggers, and symbol order
2975 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2976 the same order they were declared. This may break some debuggers.
2981 * Setting Symbols:: Giving Symbols Other Values
2982 * Symbol Names:: Symbol Names
2983 * Dot:: The Special Dot Symbol
2984 * Symbol Attributes:: Symbol Attributes
2991 A @dfn{label} is written as a symbol immediately followed by a colon
2992 @samp{:}. The symbol then represents the current value of the
2993 active location counter, and is, for example, a suitable instruction
2994 operand. You are warned if you use the same symbol to represent two
2995 different locations: the first definition overrides any other
2999 On the HPPA, the usual form for a label need not be immediately followed by a
3000 colon, but instead must start in column zero. Only one label may be defined on
3001 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3002 provides a special directive @code{.label} for defining labels more flexibly.
3005 @node Setting Symbols
3006 @section Giving Symbols Other Values
3008 @cindex assigning values to symbols
3009 @cindex symbol values, assigning
3010 A symbol can be given an arbitrary value by writing a symbol, followed
3011 by an equals sign @samp{=}, followed by an expression
3012 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3013 directive. @xref{Set,,@code{.set}}.
3016 @section Symbol Names
3018 @cindex symbol names
3019 @cindex names, symbol
3020 @ifclear SPECIAL-SYMS
3021 Symbol names begin with a letter or with one of @samp{._}. On most
3022 machines, you can also use @code{$} in symbol names; exceptions are
3023 noted in @ref{Machine Dependencies}. That character may be followed by any
3024 string of digits, letters, dollar signs (unless otherwise noted in
3025 @ref{Machine Dependencies}), and underscores.
3028 For the AMD 29K family, @samp{?} is also allowed in the
3029 body of a symbol name, though not at its beginning.
3034 Symbol names begin with a letter or with one of @samp{._}. On the
3036 H8/500, you can also use @code{$} in symbol names. That character may
3037 be followed by any string of digits, letters, dollar signs (save on the
3038 H8/300), and underscores.
3042 Case of letters is significant: @code{foo} is a different symbol name
3045 Each symbol has exactly one name. Each name in an assembly language program
3046 refers to exactly one symbol. You may use that symbol name any number of times
3049 @subheading Local Symbol Names
3051 @cindex local symbol names
3052 @cindex symbol names, local
3053 @cindex temporary symbol names
3054 @cindex symbol names, temporary
3055 Local symbols help compilers and programmers use names temporarily.
3056 They create symbols which are guaranteed to be unique over the entire scope of
3057 the input source code and which can be referred to by a simple notation.
3058 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3059 represents any positive integer). To refer to the most recent previous
3060 definition of that symbol write @samp{@b{N}b}, using the same number as when
3061 you defined the label. To refer to the next definition of a local label, write
3062 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3065 There is no restriction on how you can use these labels, and you can reuse them
3066 too. So that it is possible to repeatedly define the same local label (using
3067 the same number @samp{@b{N}}), although you can only refer to the most recently
3068 defined local label of that number (for a backwards reference) or the next
3069 definition of a specific local label for a forward reference. It is also worth
3070 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3071 implemented in a slightly more efficient manner than the others.
3082 Which is the equivalent of:
3085 label_1: branch label_3
3086 label_2: branch label_1
3087 label_3: branch label_4
3088 label_4: branch label_3
3091 Local symbol names are only a notational device. They are immediately
3092 transformed into more conventional symbol names before the assembler uses them.
3093 The symbol names stored in the symbol table, appearing in error messages and
3094 optionally emitted to the object file. The names are constructed using these
3099 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3100 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3101 used for symbols you are never intended to see. If you use the
3102 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3103 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3104 you may use them in debugging.
3107 This is the number that was used in the local label definition. So if the
3108 label is written @samp{55:} then the number is @samp{55}.
3111 This unusual character is included so you do not accidentally invent a symbol
3112 of the same name. The character has ASCII value of @samp{\002} (control-B).
3114 @item @emph{ordinal number}
3115 This is a serial number to keep the labels distinct. The first definition of
3116 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3117 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3118 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3121 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3122 @code{3:} is named @code{L3@kbd{C-B}44}.
3124 @subheading Dollar Local Labels
3125 @cindex dollar local symbols
3127 @code{@value{AS}} also supports an even more local form of local labels called
3128 dollar labels. These labels go out of scope (ie they become undefined) as soon
3129 as a non-local label is defined. Thus they remain valid for only a small
3130 region of the input source code. Normal local labels, by contrast, remain in
3131 scope for the entire file, or until they are redefined by another occurrence of
3132 the same local label.
3134 Dollar labels are defined in exactly the same way as ordinary local labels,
3135 except that instead of being terminated by a colon, they are terminated by a
3136 dollar sign. eg @samp{@b{55$}}.
3138 They can also be distinguished from ordinary local labels by their transformed
3139 name which uses ASCII character @samp{\001} (control-A) as the magic character
3140 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3141 is named @samp{L6@kbd{C-A}5}.
3144 @section The Special Dot Symbol
3146 @cindex dot (symbol)
3147 @cindex @code{.} (symbol)
3148 @cindex current address
3149 @cindex location counter
3150 The special symbol @samp{.} refers to the current address that
3151 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3152 .long .} defines @code{melvin} to contain its own address.
3153 Assigning a value to @code{.} is treated the same as a @code{.org}
3154 directive. Thus, the expression @samp{.=.+4} is the same as saying
3155 @ifclear no-space-dir
3164 @node Symbol Attributes
3165 @section Symbol Attributes
3167 @cindex symbol attributes
3168 @cindex attributes, symbol
3169 Every symbol has, as well as its name, the attributes ``Value'' and
3170 ``Type''. Depending on output format, symbols can also have auxiliary
3173 The detailed definitions are in @file{a.out.h}.
3176 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3177 all these attributes, and probably won't warn you. This makes the
3178 symbol an externally defined symbol, which is generally what you
3182 * Symbol Value:: Value
3183 * Symbol Type:: Type
3186 * a.out Symbols:: Symbol Attributes: @code{a.out}
3190 * a.out Symbols:: Symbol Attributes: @code{a.out}
3193 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3198 * COFF Symbols:: Symbol Attributes for COFF
3201 * SOM Symbols:: Symbol Attributes for SOM
3208 @cindex value of a symbol
3209 @cindex symbol value
3210 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3211 location in the text, data, bss or absolute sections the value is the
3212 number of addresses from the start of that section to the label.
3213 Naturally for text, data and bss sections the value of a symbol changes
3214 as @code{@value{LD}} changes section base addresses during linking. Absolute
3215 symbols' values do not change during linking: that is why they are
3218 The value of an undefined symbol is treated in a special way. If it is
3219 0 then the symbol is not defined in this assembler source file, and
3220 @code{@value{LD}} tries to determine its value from other files linked into the
3221 same program. You make this kind of symbol simply by mentioning a symbol
3222 name without defining it. A non-zero value represents a @code{.comm}
3223 common declaration. The value is how much common storage to reserve, in
3224 bytes (addresses). The symbol refers to the first address of the
3230 @cindex type of a symbol
3232 The type attribute of a symbol contains relocation (section)
3233 information, any flag settings indicating that a symbol is external, and
3234 (optionally), other information for linkers and debuggers. The exact
3235 format depends on the object-code output format in use.
3240 @c The following avoids a "widow" subsection title. @group would be
3241 @c better if it were available outside examples.
3244 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3246 @cindex @code{b.out} symbol attributes
3247 @cindex symbol attributes, @code{b.out}
3248 These symbol attributes appear only when @command{@value{AS}} is configured for
3249 one of the Berkeley-descended object output formats---@code{a.out} or
3255 @subsection Symbol Attributes: @code{a.out}
3257 @cindex @code{a.out} symbol attributes
3258 @cindex symbol attributes, @code{a.out}
3264 @subsection Symbol Attributes: @code{a.out}
3266 @cindex @code{a.out} symbol attributes
3267 @cindex symbol attributes, @code{a.out}
3271 * Symbol Desc:: Descriptor
3272 * Symbol Other:: Other
3276 @subsubsection Descriptor
3278 @cindex descriptor, of @code{a.out} symbol
3279 This is an arbitrary 16-bit value. You may establish a symbol's
3280 descriptor value by using a @code{.desc} statement
3281 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3282 @command{@value{AS}}.
3285 @subsubsection Other
3287 @cindex other attribute, of @code{a.out} symbol
3288 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3293 @subsection Symbol Attributes for COFF
3295 @cindex COFF symbol attributes
3296 @cindex symbol attributes, COFF
3298 The COFF format supports a multitude of auxiliary symbol attributes;
3299 like the primary symbol attributes, they are set between @code{.def} and
3300 @code{.endef} directives.
3302 @subsubsection Primary Attributes
3304 @cindex primary attributes, COFF symbols
3305 The symbol name is set with @code{.def}; the value and type,
3306 respectively, with @code{.val} and @code{.type}.
3308 @subsubsection Auxiliary Attributes
3310 @cindex auxiliary attributes, COFF symbols
3311 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3312 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3313 information for COFF.
3318 @subsection Symbol Attributes for SOM
3320 @cindex SOM symbol attributes
3321 @cindex symbol attributes, SOM
3323 The SOM format for the HPPA supports a multitude of symbol attributes set with
3324 the @code{.EXPORT} and @code{.IMPORT} directives.
3326 The attributes are described in @cite{HP9000 Series 800 Assembly
3327 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3328 @code{EXPORT} assembler directive documentation.
3332 @chapter Expressions
3336 @cindex numeric values
3337 An @dfn{expression} specifies an address or numeric value.
3338 Whitespace may precede and/or follow an expression.
3340 The result of an expression must be an absolute number, or else an offset into
3341 a particular section. If an expression is not absolute, and there is not
3342 enough information when @command{@value{AS}} sees the expression to know its
3343 section, a second pass over the source program might be necessary to interpret
3344 the expression---but the second pass is currently not implemented.
3345 @command{@value{AS}} aborts with an error message in this situation.
3348 * Empty Exprs:: Empty Expressions
3349 * Integer Exprs:: Integer Expressions
3353 @section Empty Expressions
3355 @cindex empty expressions
3356 @cindex expressions, empty
3357 An empty expression has no value: it is just whitespace or null.
3358 Wherever an absolute expression is required, you may omit the
3359 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3360 is compatible with other assemblers.
3363 @section Integer Expressions
3365 @cindex integer expressions
3366 @cindex expressions, integer
3367 An @dfn{integer expression} is one or more @emph{arguments} delimited
3368 by @emph{operators}.
3371 * Arguments:: Arguments
3372 * Operators:: Operators
3373 * Prefix Ops:: Prefix Operators
3374 * Infix Ops:: Infix Operators
3378 @subsection Arguments
3380 @cindex expression arguments
3381 @cindex arguments in expressions
3382 @cindex operands in expressions
3383 @cindex arithmetic operands
3384 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3385 contexts arguments are sometimes called ``arithmetic operands''. In
3386 this manual, to avoid confusing them with the ``instruction operands'' of
3387 the machine language, we use the term ``argument'' to refer to parts of
3388 expressions only, reserving the word ``operand'' to refer only to machine
3389 instruction operands.
3391 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3392 @var{section} is one of text, data, bss, absolute,
3393 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3396 Numbers are usually integers.
3398 A number can be a flonum or bignum. In this case, you are warned
3399 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3400 these 32 bits are an integer. You may write integer-manipulating
3401 instructions that act on exotic constants, compatible with other
3404 @cindex subexpressions
3405 Subexpressions are a left parenthesis @samp{(} followed by an integer
3406 expression, followed by a right parenthesis @samp{)}; or a prefix
3407 operator followed by an argument.
3410 @subsection Operators
3412 @cindex operators, in expressions
3413 @cindex arithmetic functions
3414 @cindex functions, in expressions
3415 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3416 operators are followed by an argument. Infix operators appear
3417 between their arguments. Operators may be preceded and/or followed by
3421 @subsection Prefix Operator
3423 @cindex prefix operators
3424 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3425 one argument, which must be absolute.
3427 @c the tex/end tex stuff surrounding this small table is meant to make
3428 @c it align, on the printed page, with the similar table in the next
3429 @c section (which is inside an enumerate).
3431 \global\advance\leftskip by \itemindent
3436 @dfn{Negation}. Two's complement negation.
3438 @dfn{Complementation}. Bitwise not.
3442 \global\advance\leftskip by -\itemindent
3446 @subsection Infix Operators
3448 @cindex infix operators
3449 @cindex operators, permitted arguments
3450 @dfn{Infix operators} take two arguments, one on either side. Operators
3451 have precedence, but operations with equal precedence are performed left
3452 to right. Apart from @code{+} or @option{-}, both arguments must be
3453 absolute, and the result is absolute.
3456 @cindex operator precedence
3457 @cindex precedence of operators
3464 @dfn{Multiplication}.
3467 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3474 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3478 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3482 Intermediate precedence
3487 @dfn{Bitwise Inclusive Or}.
3493 @dfn{Bitwise Exclusive Or}.
3496 @dfn{Bitwise Or Not}.
3503 @cindex addition, permitted arguments
3504 @cindex plus, permitted arguments
3505 @cindex arguments for addition
3507 @dfn{Addition}. If either argument is absolute, the result has the section of
3508 the other argument. You may not add together arguments from different
3511 @cindex subtraction, permitted arguments
3512 @cindex minus, permitted arguments
3513 @cindex arguments for subtraction
3515 @dfn{Subtraction}. If the right argument is absolute, the
3516 result has the section of the left argument.
3517 If both arguments are in the same section, the result is absolute.
3518 You may not subtract arguments from different sections.
3519 @c FIXME is there still something useful to say about undefined - undefined ?
3521 @cindex comparison expressions
3522 @cindex expressions, comparison
3526 @dfn{Is Not Equal To}
3530 @dfn{Is Greater Than}
3532 @dfn{Is Greater Than Or Equal To}
3534 @dfn{Is Less Than Or Equal To}
3536 The comparison operators can be used as infix operators. A true results has a
3537 value of -1 whereas a false result has a value of 0. Note, these operators
3538 perform signed comparisons.
3541 @item Lowest Precedence
3550 These two logical operations can be used to combine the results of sub
3551 expressions. Note, unlike the comparison operators a true result returns a
3552 value of 1 but a false results does still return 0. Also note that the logical
3553 or operator has a slightly lower precedence than logical and.
3558 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3559 address; you can only have a defined section in one of the two arguments.
3562 @chapter Assembler Directives
3564 @cindex directives, machine independent
3565 @cindex pseudo-ops, machine independent
3566 @cindex machine independent directives
3567 All assembler directives have names that begin with a period (@samp{.}).
3568 The rest of the name is letters, usually in lower case.
3570 This chapter discusses directives that are available regardless of the
3571 target machine configuration for the @sc{gnu} assembler.
3573 Some machine configurations provide additional directives.
3574 @xref{Machine Dependencies}.
3577 @ifset machine-directives
3578 @xref{Machine Dependencies} for additional directives.
3583 * Abort:: @code{.abort}
3585 * ABORT:: @code{.ABORT}
3588 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3589 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3590 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3591 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3592 * Byte:: @code{.byte @var{expressions}}
3593 * Comm:: @code{.comm @var{symbol} , @var{length} }
3594 * Data:: @code{.data @var{subsection}}
3596 * Def:: @code{.def @var{name}}
3599 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3605 * Double:: @code{.double @var{flonums}}
3606 * Eject:: @code{.eject}
3607 * Else:: @code{.else}
3608 * Elseif:: @code{.elseif}
3611 * Endef:: @code{.endef}
3614 * Endfunc:: @code{.endfunc}
3615 * Endif:: @code{.endif}
3616 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3617 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3619 * Exitm:: @code{.exitm}
3620 * Extern:: @code{.extern}
3621 * Fail:: @code{.fail}
3622 @ifclear no-file-dir
3623 * File:: @code{.file @var{string}}
3626 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3627 * Float:: @code{.float @var{flonums}}
3628 * Func:: @code{.func}
3629 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3631 * Hidden:: @code{.hidden @var{names}}
3634 * hword:: @code{.hword @var{expressions}}
3635 * Ident:: @code{.ident}
3636 * If:: @code{.if @var{absolute expression}}
3637 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3638 * Include:: @code{.include "@var{file}"}
3639 * Int:: @code{.int @var{expressions}}
3641 * Internal:: @code{.internal @var{names}}
3644 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3645 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3646 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3647 * Lflags:: @code{.lflags}
3648 @ifclear no-line-dir
3649 * Line:: @code{.line @var{line-number}}
3652 * Ln:: @code{.ln @var{line-number}}
3653 * Linkonce:: @code{.linkonce [@var{type}]}
3654 * List:: @code{.list}
3655 * Long:: @code{.long @var{expressions}}
3657 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3660 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3661 * MRI:: @code{.mri @var{val}}
3662 * Nolist:: @code{.nolist}
3663 * Octa:: @code{.octa @var{bignums}}
3664 * Org:: @code{.org @var{new-lc} , @var{fill}}
3665 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3667 * PopSection:: @code{.popsection}
3668 * Previous:: @code{.previous}
3671 * Print:: @code{.print @var{string}}
3673 * Protected:: @code{.protected @var{names}}
3676 * Psize:: @code{.psize @var{lines}, @var{columns}}
3677 * Purgem:: @code{.purgem @var{name}}
3679 * PushSection:: @code{.pushsection @var{name}}
3682 * Quad:: @code{.quad @var{bignums}}
3683 * Rept:: @code{.rept @var{count}}
3684 * Sbttl:: @code{.sbttl "@var{subheading}"}
3686 * Scl:: @code{.scl @var{class}}
3687 * Section:: @code{.section @var{name}, @var{subsection}}
3690 * Set:: @code{.set @var{symbol}, @var{expression}}
3691 * Short:: @code{.short @var{expressions}}
3692 * Single:: @code{.single @var{flonums}}
3693 * Size:: @code{.size [@var{name} , @var{expression}]}
3694 * Skip:: @code{.skip @var{size} , @var{fill}}
3695 * Sleb128:: @code{.sleb128 @var{expressions}}
3696 * Space:: @code{.space @var{size} , @var{fill}}
3698 * Stab:: @code{.stabd, .stabn, .stabs}
3701 * String:: @code{.string "@var{str}"}
3702 * Struct:: @code{.struct @var{expression}}
3704 * SubSection:: @code{.subsection}
3705 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3709 * Tag:: @code{.tag @var{structname}}
3712 * Text:: @code{.text @var{subsection}}
3713 * Title:: @code{.title "@var{heading}"}
3714 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3715 * Uleb128:: @code{.uleb128 @var{expressions}}
3717 * Val:: @code{.val @var{addr}}
3721 * Version:: @code{.version "@var{string}"}
3722 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3723 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3724 * Weak:: @code{.weak @var{names}}
3727 * Word:: @code{.word @var{expressions}}
3728 * Deprecated:: Deprecated Directives
3732 @section @code{.abort}
3734 @cindex @code{abort} directive
3735 @cindex stopping the assembly
3736 This directive stops the assembly immediately. It is for
3737 compatibility with other assemblers. The original idea was that the
3738 assembly language source would be piped into the assembler. If the sender
3739 of the source quit, it could use this directive tells @command{@value{AS}} to
3740 quit also. One day @code{.abort} will not be supported.
3744 @section @code{.ABORT}
3746 @cindex @code{ABORT} directive
3747 When producing COFF output, @command{@value{AS}} accepts this directive as a
3748 synonym for @samp{.abort}.
3751 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3757 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3759 @cindex padding the location counter
3760 @cindex @code{align} directive
3761 Pad the location counter (in the current subsection) to a particular storage
3762 boundary. The first expression (which must be absolute) is the alignment
3763 required, as described below.
3765 The second expression (also absolute) gives the fill value to be stored in the
3766 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3767 padding bytes are normally zero. However, on some systems, if the section is
3768 marked as containing code and the fill value is omitted, the space is filled
3769 with no-op instructions.
3771 The third expression is also absolute, and is also optional. If it is present,
3772 it is the maximum number of bytes that should be skipped by this alignment
3773 directive. If doing the alignment would require skipping more bytes than the
3774 specified maximum, then the alignment is not done at all. You can omit the
3775 fill value (the second argument) entirely by simply using two commas after the
3776 required alignment; this can be useful if you want the alignment to be filled
3777 with no-op instructions when appropriate.
3779 The way the required alignment is specified varies from system to system.
3780 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3782 the first expression is the
3783 alignment request in bytes. For example @samp{.align 8} advances
3784 the location counter until it is a multiple of 8. If the location counter
3785 is already a multiple of 8, no change is needed.
3787 For other systems, including the i386 using a.out format, and the arm and
3788 strongarm, it is the
3789 number of low-order zero bits the location counter must have after
3790 advancement. For example @samp{.align 3} advances the location
3791 counter until it a multiple of 8. If the location counter is already a
3792 multiple of 8, no change is needed.
3794 This inconsistency is due to the different behaviors of the various
3795 native assemblers for these systems which GAS must emulate.
3796 GAS also provides @code{.balign} and @code{.p2align} directives,
3797 described later, which have a consistent behavior across all
3798 architectures (but are specific to GAS).
3801 @section @code{.ascii "@var{string}"}@dots{}
3803 @cindex @code{ascii} directive
3804 @cindex string literals
3805 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3806 separated by commas. It assembles each string (with no automatic
3807 trailing zero byte) into consecutive addresses.
3810 @section @code{.asciz "@var{string}"}@dots{}
3812 @cindex @code{asciz} directive
3813 @cindex zero-terminated strings
3814 @cindex null-terminated strings
3815 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3816 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3819 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3821 @cindex padding the location counter given number of bytes
3822 @cindex @code{balign} directive
3823 Pad the location counter (in the current subsection) to a particular
3824 storage boundary. The first expression (which must be absolute) is the
3825 alignment request in bytes. For example @samp{.balign 8} advances
3826 the location counter until it is a multiple of 8. If the location counter
3827 is already a multiple of 8, no change is needed.
3829 The second expression (also absolute) gives the fill value to be stored in the
3830 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3831 padding bytes are normally zero. However, on some systems, if the section is
3832 marked as containing code and the fill value is omitted, the space is filled
3833 with no-op instructions.
3835 The third expression is also absolute, and is also optional. If it is present,
3836 it is the maximum number of bytes that should be skipped by this alignment
3837 directive. If doing the alignment would require skipping more bytes than the
3838 specified maximum, then the alignment is not done at all. You can omit the
3839 fill value (the second argument) entirely by simply using two commas after the
3840 required alignment; this can be useful if you want the alignment to be filled
3841 with no-op instructions when appropriate.
3843 @cindex @code{balignw} directive
3844 @cindex @code{balignl} directive
3845 The @code{.balignw} and @code{.balignl} directives are variants of the
3846 @code{.balign} directive. The @code{.balignw} directive treats the fill
3847 pattern as a two byte word value. The @code{.balignl} directives treats the
3848 fill pattern as a four byte longword value. For example, @code{.balignw
3849 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3850 filled in with the value 0x368d (the exact placement of the bytes depends upon
3851 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3855 @section @code{.byte @var{expressions}}
3857 @cindex @code{byte} directive
3858 @cindex integers, one byte
3859 @code{.byte} expects zero or more expressions, separated by commas.
3860 Each expression is assembled into the next byte.
3863 @section @code{.comm @var{symbol} , @var{length} }
3865 @cindex @code{comm} directive
3866 @cindex symbol, common
3867 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3868 common symbol in one object file may be merged with a defined or common symbol
3869 of the same name in another object file. If @code{@value{LD}} does not see a
3870 definition for the symbol--just one or more common symbols--then it will
3871 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3872 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3873 the same name, and they do not all have the same size, it will allocate space
3874 using the largest size.
3877 When using ELF, the @code{.comm} directive takes an optional third argument.
3878 This is the desired alignment of the symbol, specified as a byte boundary (for
3879 example, an alignment of 16 means that the least significant 4 bits of the
3880 address should be zero). The alignment must be an absolute expression, and it
3881 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3882 for the common symbol, it will use the alignment when placing the symbol. If
3883 no alignment is specified, @command{@value{AS}} will set the alignment to the
3884 largest power of two less than or equal to the size of the symbol, up to a
3889 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3890 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3894 @section @code{.data @var{subsection}}
3896 @cindex @code{data} directive
3897 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3898 end of the data subsection numbered @var{subsection} (which is an
3899 absolute expression). If @var{subsection} is omitted, it defaults
3904 @section @code{.def @var{name}}
3906 @cindex @code{def} directive
3907 @cindex COFF symbols, debugging
3908 @cindex debugging COFF symbols
3909 Begin defining debugging information for a symbol @var{name}; the
3910 definition extends until the @code{.endef} directive is encountered.
3913 This directive is only observed when @command{@value{AS}} is configured for COFF
3914 format output; when producing @code{b.out}, @samp{.def} is recognized,
3921 @section @code{.desc @var{symbol}, @var{abs-expression}}
3923 @cindex @code{desc} directive
3924 @cindex COFF symbol descriptor
3925 @cindex symbol descriptor, COFF
3926 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3927 to the low 16 bits of an absolute expression.
3930 The @samp{.desc} directive is not available when @command{@value{AS}} is
3931 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3932 object format. For the sake of compatibility, @command{@value{AS}} accepts
3933 it, but produces no output, when configured for COFF.
3939 @section @code{.dim}
3941 @cindex @code{dim} directive
3942 @cindex COFF auxiliary symbol information
3943 @cindex auxiliary symbol information, COFF
3944 This directive is generated by compilers to include auxiliary debugging
3945 information in the symbol table. It is only permitted inside
3946 @code{.def}/@code{.endef} pairs.
3949 @samp{.dim} is only meaningful when generating COFF format output; when
3950 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3956 @section @code{.double @var{flonums}}
3958 @cindex @code{double} directive
3959 @cindex floating point numbers (double)
3960 @code{.double} expects zero or more flonums, separated by commas. It
3961 assembles floating point numbers.
3963 The exact kind of floating point numbers emitted depends on how
3964 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3968 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3969 in @sc{ieee} format.
3974 @section @code{.eject}
3976 @cindex @code{eject} directive
3977 @cindex new page, in listings
3978 @cindex page, in listings
3979 @cindex listing control: new page
3980 Force a page break at this point, when generating assembly listings.
3983 @section @code{.else}
3985 @cindex @code{else} directive
3986 @code{.else} is part of the @command{@value{AS}} support for conditional
3987 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3988 of code to be assembled if the condition for the preceding @code{.if}
3992 @section @code{.elseif}
3994 @cindex @code{elseif} directive
3995 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3996 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3997 @code{.if} block that would otherwise fill the entire @code{.else} section.
4000 @section @code{.end}
4002 @cindex @code{end} directive
4003 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4004 process anything in the file past the @code{.end} directive.
4008 @section @code{.endef}
4010 @cindex @code{endef} directive
4011 This directive flags the end of a symbol definition begun with
4015 @samp{.endef} is only meaningful when generating COFF format output; if
4016 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4017 directive but ignores it.
4022 @section @code{.endfunc}
4023 @cindex @code{endfunc} directive
4024 @code{.endfunc} marks the end of a function specified with @code{.func}.
4027 @section @code{.endif}
4029 @cindex @code{endif} directive
4030 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4031 it marks the end of a block of code that is only assembled
4032 conditionally. @xref{If,,@code{.if}}.
4035 @section @code{.equ @var{symbol}, @var{expression}}
4037 @cindex @code{equ} directive
4038 @cindex assigning values to symbols
4039 @cindex symbols, assigning values to
4040 This directive sets the value of @var{symbol} to @var{expression}.
4041 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4044 The syntax for @code{equ} on the HPPA is
4045 @samp{@var{symbol} .equ @var{expression}}.
4049 @section @code{.equiv @var{symbol}, @var{expression}}
4050 @cindex @code{equiv} directive
4051 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4052 the assembler will signal an error if @var{symbol} is already defined.
4054 Except for the contents of the error message, this is roughly equivalent to
4063 @section @code{.err}
4064 @cindex @code{err} directive
4065 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4066 message and, unless the @option{-Z} option was used, it will not generate an
4067 object file. This can be used to signal error an conditionally compiled code.
4070 @section @code{.exitm}
4071 Exit early from the current macro definition. @xref{Macro}.
4074 @section @code{.extern}
4076 @cindex @code{extern} directive
4077 @code{.extern} is accepted in the source program---for compatibility
4078 with other assemblers---but it is ignored. @command{@value{AS}} treats
4079 all undefined symbols as external.
4082 @section @code{.fail @var{expression}}
4084 @cindex @code{fail} directive
4085 Generates an error or a warning. If the value of the @var{expression} is 500
4086 or more, @command{@value{AS}} will print a warning message. If the value is less
4087 than 500, @command{@value{AS}} will print an error message. The message will
4088 include the value of @var{expression}. This can occasionally be useful inside
4089 complex nested macros or conditional assembly.
4091 @ifclear no-file-dir
4093 @section @code{.file @var{string}}
4095 @cindex @code{file} directive
4096 @cindex logical file name
4097 @cindex file name, logical
4098 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4099 file. @var{string} is the new file name. In general, the filename is
4100 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4101 to specify an empty file name, you must give the quotes--@code{""}. This
4102 statement may go away in future: it is only recognized to be compatible with
4103 old @command{@value{AS}} programs.
4105 In some configurations of @command{@value{AS}}, @code{.file} has already been
4106 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4111 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4113 @cindex @code{fill} directive
4114 @cindex writing patterns in memory
4115 @cindex patterns, writing in memory
4116 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4117 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4118 may be zero or more. @var{Size} may be zero or more, but if it is
4119 more than 8, then it is deemed to have the value 8, compatible with
4120 other people's assemblers. The contents of each @var{repeat} bytes
4121 is taken from an 8-byte number. The highest order 4 bytes are
4122 zero. The lowest order 4 bytes are @var{value} rendered in the
4123 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4124 Each @var{size} bytes in a repetition is taken from the lowest order
4125 @var{size} bytes of this number. Again, this bizarre behavior is
4126 compatible with other people's assemblers.
4128 @var{size} and @var{value} are optional.
4129 If the second comma and @var{value} are absent, @var{value} is
4130 assumed zero. If the first comma and following tokens are absent,
4131 @var{size} is assumed to be 1.
4134 @section @code{.float @var{flonums}}
4136 @cindex floating point numbers (single)
4137 @cindex @code{float} directive
4138 This directive assembles zero or more flonums, separated by commas. It
4139 has the same effect as @code{.single}.
4141 The exact kind of floating point numbers emitted depends on how
4142 @command{@value{AS}} is configured.
4143 @xref{Machine Dependencies}.
4147 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4148 in @sc{ieee} format.
4153 @section @code{.func @var{name}[,@var{label}]}
4154 @cindex @code{func} directive
4155 @code{.func} emits debugging information to denote function @var{name}, and
4156 is ignored unless the file is assembled with debugging enabled.
4157 Only @samp{--gstabs} is currently supported.
4158 @var{label} is the entry point of the function and if omitted @var{name}
4159 prepended with the @samp{leading char} is used.
4160 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4161 All functions are currently defined to have @code{void} return type.
4162 The function must be terminated with @code{.endfunc}.
4165 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4167 @cindex @code{global} directive
4168 @cindex symbol, making visible to linker
4169 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4170 @var{symbol} in your partial program, its value is made available to
4171 other partial programs that are linked with it. Otherwise,
4172 @var{symbol} takes its attributes from a symbol of the same name
4173 from another file linked into the same program.
4175 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4176 compatibility with other assemblers.
4179 On the HPPA, @code{.global} is not always enough to make it accessible to other
4180 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4181 @xref{HPPA Directives,, HPPA Assembler Directives}.
4186 @section @code{.hidden @var{names}}
4188 @cindex @code{.hidden} directive
4190 This one of the ELF visibility directives. The other two are
4191 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4192 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4194 This directive overrides the named symbols default visibility (which is set by
4195 their binding: local, global or weak). The directive sets the visibility to
4196 @code{hidden} which means that the symbols are not visible to other components.
4197 Such symbols are always considered to be @code{protected} as well.
4201 @section @code{.hword @var{expressions}}
4203 @cindex @code{hword} directive
4204 @cindex integers, 16-bit
4205 @cindex numbers, 16-bit
4206 @cindex sixteen bit integers
4207 This expects zero or more @var{expressions}, and emits
4208 a 16 bit number for each.
4211 This directive is a synonym for @samp{.short}; depending on the target
4212 architecture, it may also be a synonym for @samp{.word}.
4216 This directive is a synonym for @samp{.short}.
4219 This directive is a synonym for both @samp{.short} and @samp{.word}.
4224 @section @code{.ident}
4226 @cindex @code{ident} directive
4227 This directive is used by some assemblers to place tags in object files.
4228 @command{@value{AS}} simply accepts the directive for source-file
4229 compatibility with such assemblers, but does not actually emit anything
4233 @section @code{.if @var{absolute expression}}
4235 @cindex conditional assembly
4236 @cindex @code{if} directive
4237 @code{.if} marks the beginning of a section of code which is only
4238 considered part of the source program being assembled if the argument
4239 (which must be an @var{absolute expression}) is non-zero. The end of
4240 the conditional section of code must be marked by @code{.endif}
4241 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4242 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4243 If you have several conditions to check, @code{.elseif} may be used to avoid
4244 nesting blocks if/else within each subsequent @code{.else} block.
4246 The following variants of @code{.if} are also supported:
4248 @cindex @code{ifdef} directive
4249 @item .ifdef @var{symbol}
4250 Assembles the following section of code if the specified @var{symbol}
4253 @cindex @code{ifc} directive
4254 @item .ifc @var{string1},@var{string2}
4255 Assembles the following section of code if the two strings are the same. The
4256 strings may be optionally quoted with single quotes. If they are not quoted,
4257 the first string stops at the first comma, and the second string stops at the
4258 end of the line. Strings which contain whitespace should be quoted. The
4259 string comparison is case sensitive.
4261 @cindex @code{ifeq} directive
4262 @item .ifeq @var{absolute expression}
4263 Assembles the following section of code if the argument is zero.
4265 @cindex @code{ifeqs} directive
4266 @item .ifeqs @var{string1},@var{string2}
4267 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4269 @cindex @code{ifge} directive
4270 @item .ifge @var{absolute expression}
4271 Assembles the following section of code if the argument is greater than or
4274 @cindex @code{ifgt} directive
4275 @item .ifgt @var{absolute expression}
4276 Assembles the following section of code if the argument is greater than zero.
4278 @cindex @code{ifle} directive
4279 @item .ifle @var{absolute expression}
4280 Assembles the following section of code if the argument is less than or equal
4283 @cindex @code{iflt} directive
4284 @item .iflt @var{absolute expression}
4285 Assembles the following section of code if the argument is less than zero.
4287 @cindex @code{ifnc} directive
4288 @item .ifnc @var{string1},@var{string2}.
4289 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4290 following section of code if the two strings are not the same.
4292 @cindex @code{ifndef} directive
4293 @cindex @code{ifnotdef} directive
4294 @item .ifndef @var{symbol}
4295 @itemx .ifnotdef @var{symbol}
4296 Assembles the following section of code if the specified @var{symbol}
4297 has not been defined. Both spelling variants are equivalent.
4299 @cindex @code{ifne} directive
4300 @item .ifne @var{absolute expression}
4301 Assembles the following section of code if the argument is not equal to zero
4302 (in other words, this is equivalent to @code{.if}).
4304 @cindex @code{ifnes} directive
4305 @item .ifnes @var{string1},@var{string2}
4306 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4307 following section of code if the two strings are not the same.
4311 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4313 @cindex @code{incbin} directive
4314 @cindex binary files, including
4315 The @code{incbin} directive includes @var{file} verbatim at the current
4316 location. You can control the search paths used with the @samp{-I} command-line
4317 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4320 The @var{skip} argument skips a number of bytes from the start of the
4321 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4322 read. Note that the data is not aligned in any way, so it is the user's
4323 responsibility to make sure that proper alignment is provided both before and
4324 after the @code{incbin} directive.
4327 @section @code{.include "@var{file}"}
4329 @cindex @code{include} directive
4330 @cindex supporting files, including
4331 @cindex files, including
4332 This directive provides a way to include supporting files at specified
4333 points in your source program. The code from @var{file} is assembled as
4334 if it followed the point of the @code{.include}; when the end of the
4335 included file is reached, assembly of the original file continues. You
4336 can control the search paths used with the @samp{-I} command-line option
4337 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4341 @section @code{.int @var{expressions}}
4343 @cindex @code{int} directive
4344 @cindex integers, 32-bit
4345 Expect zero or more @var{expressions}, of any section, separated by commas.
4346 For each expression, emit a number that, at run time, is the value of that
4347 expression. The byte order and bit size of the number depends on what kind
4348 of target the assembly is for.
4352 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4353 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4360 @section @code{.internal @var{names}}
4362 @cindex @code{.internal} directive
4364 This one of the ELF visibility directives. The other two are
4365 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4366 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4368 This directive overrides the named symbols default visibility (which is set by
4369 their binding: local, global or weak). The directive sets the visibility to
4370 @code{internal} which means that the symbols are considered to be @code{hidden}
4371 (ie not visible to other components), and that some extra, processor specific
4372 processing must also be performed upon the symbols as well.
4376 @section @code{.irp @var{symbol},@var{values}}@dots{}
4378 @cindex @code{irp} directive
4379 Evaluate a sequence of statements assigning different values to @var{symbol}.
4380 The sequence of statements starts at the @code{.irp} directive, and is
4381 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4382 set to @var{value}, and the sequence of statements is assembled. If no
4383 @var{value} is listed, the sequence of statements is assembled once, with
4384 @var{symbol} set to the null string. To refer to @var{symbol} within the
4385 sequence of statements, use @var{\symbol}.
4387 For example, assembling
4395 is equivalent to assembling
4404 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4406 @cindex @code{irpc} directive
4407 Evaluate a sequence of statements assigning different values to @var{symbol}.
4408 The sequence of statements starts at the @code{.irpc} directive, and is
4409 terminated by an @code{.endr} directive. For each character in @var{value},
4410 @var{symbol} is set to the character, and the sequence of statements is
4411 assembled. If no @var{value} is listed, the sequence of statements is
4412 assembled once, with @var{symbol} set to the null string. To refer to
4413 @var{symbol} within the sequence of statements, use @var{\symbol}.
4415 For example, assembling
4423 is equivalent to assembling
4432 @section @code{.lcomm @var{symbol} , @var{length}}
4434 @cindex @code{lcomm} directive
4435 @cindex local common symbols
4436 @cindex symbols, local common
4437 Reserve @var{length} (an absolute expression) bytes for a local common
4438 denoted by @var{symbol}. The section and value of @var{symbol} are
4439 those of the new local common. The addresses are allocated in the bss
4440 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4441 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4442 not visible to @code{@value{LD}}.
4445 Some targets permit a third argument to be used with @code{.lcomm}. This
4446 argument specifies the desired alignment of the symbol in the bss section.
4450 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4451 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4455 @section @code{.lflags}
4457 @cindex @code{lflags} directive (ignored)
4458 @command{@value{AS}} accepts this directive, for compatibility with other
4459 assemblers, but ignores it.
4461 @ifclear no-line-dir
4463 @section @code{.line @var{line-number}}
4465 @cindex @code{line} directive
4469 @section @code{.ln @var{line-number}}
4471 @cindex @code{ln} directive
4473 @cindex logical line number
4475 Change the logical line number. @var{line-number} must be an absolute
4476 expression. The next line has that logical line number. Therefore any other
4477 statements on the current line (after a statement separator character) are
4478 reported as on logical line number @var{line-number} @minus{} 1. One day
4479 @command{@value{AS}} will no longer support this directive: it is recognized only
4480 for compatibility with existing assembler programs.
4484 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4485 not available; use the synonym @code{.ln} in that context.
4490 @ifclear no-line-dir
4491 Even though this is a directive associated with the @code{a.out} or
4492 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4493 when producing COFF output, and treats @samp{.line} as though it
4494 were the COFF @samp{.ln} @emph{if} it is found outside a
4495 @code{.def}/@code{.endef} pair.
4497 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4498 used by compilers to generate auxiliary symbol information for
4503 @section @code{.linkonce [@var{type}]}
4505 @cindex @code{linkonce} directive
4506 @cindex common sections
4507 Mark the current section so that the linker only includes a single copy of it.
4508 This may be used to include the same section in several different object files,
4509 but ensure that the linker will only include it once in the final output file.
4510 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4511 Duplicate sections are detected based on the section name, so it should be
4514 This directive is only supported by a few object file formats; as of this
4515 writing, the only object file format which supports it is the Portable
4516 Executable format used on Windows NT.
4518 The @var{type} argument is optional. If specified, it must be one of the
4519 following strings. For example:
4523 Not all types may be supported on all object file formats.
4527 Silently discard duplicate sections. This is the default.
4530 Warn if there are duplicate sections, but still keep only one copy.
4533 Warn if any of the duplicates have different sizes.
4536 Warn if any of the duplicates do not have exactly the same contents.
4540 @section @code{.ln @var{line-number}}
4542 @cindex @code{ln} directive
4543 @ifclear no-line-dir
4544 @samp{.ln} is a synonym for @samp{.line}.
4547 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4548 must be an absolute expression. The next line has that logical
4549 line number, so any other statements on the current line (after a
4550 statement separator character @code{;}) are reported as on logical
4551 line number @var{line-number} @minus{} 1.
4554 This directive is accepted, but ignored, when @command{@value{AS}} is
4555 configured for @code{b.out}; its effect is only associated with COFF
4561 @section @code{.mri @var{val}}
4563 @cindex @code{mri} directive
4564 @cindex MRI mode, temporarily
4565 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4566 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4567 affects code assembled until the next @code{.mri} directive, or until the end
4568 of the file. @xref{M, MRI mode, MRI mode}.
4571 @section @code{.list}
4573 @cindex @code{list} directive
4574 @cindex listing control, turning on
4575 Control (in conjunction with the @code{.nolist} directive) whether or
4576 not assembly listings are generated. These two directives maintain an
4577 internal counter (which is zero initially). @code{.list} increments the
4578 counter, and @code{.nolist} decrements it. Assembly listings are
4579 generated whenever the counter is greater than zero.
4581 By default, listings are disabled. When you enable them (with the
4582 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4583 the initial value of the listing counter is one.
4586 @section @code{.long @var{expressions}}
4588 @cindex @code{long} directive
4589 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4592 @c no one seems to know what this is for or whether this description is
4593 @c what it really ought to do
4595 @section @code{.lsym @var{symbol}, @var{expression}}
4597 @cindex @code{lsym} directive
4598 @cindex symbol, not referenced in assembly
4599 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4600 the hash table, ensuring it cannot be referenced by name during the
4601 rest of the assembly. This sets the attributes of the symbol to be
4602 the same as the expression value:
4604 @var{other} = @var{descriptor} = 0
4605 @var{type} = @r{(section of @var{expression})}
4606 @var{value} = @var{expression}
4609 The new symbol is not flagged as external.
4613 @section @code{.macro}
4616 The commands @code{.macro} and @code{.endm} allow you to define macros that
4617 generate assembly output. For example, this definition specifies a macro
4618 @code{sum} that puts a sequence of numbers into memory:
4621 .macro sum from=0, to=5
4630 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4642 @item .macro @var{macname}
4643 @itemx .macro @var{macname} @var{macargs} @dots{}
4644 @cindex @code{macro} directive
4645 Begin the definition of a macro called @var{macname}. If your macro
4646 definition requires arguments, specify their names after the macro name,
4647 separated by commas or spaces. You can supply a default value for any
4648 macro argument by following the name with @samp{=@var{deflt}}. For
4649 example, these are all valid @code{.macro} statements:
4653 Begin the definition of a macro called @code{comm}, which takes no
4656 @item .macro plus1 p, p1
4657 @itemx .macro plus1 p p1
4658 Either statement begins the definition of a macro called @code{plus1},
4659 which takes two arguments; within the macro definition, write
4660 @samp{\p} or @samp{\p1} to evaluate the arguments.
4662 @item .macro reserve_str p1=0 p2
4663 Begin the definition of a macro called @code{reserve_str}, with two
4664 arguments. The first argument has a default value, but not the second.
4665 After the definition is complete, you can call the macro either as
4666 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4667 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4668 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4669 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4672 When you call a macro, you can specify the argument values either by
4673 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4674 @samp{sum to=17, from=9}.
4677 @cindex @code{endm} directive
4678 Mark the end of a macro definition.
4681 @cindex @code{exitm} directive
4682 Exit early from the current macro definition.
4684 @cindex number of macros executed
4685 @cindex macros, count executed
4687 @command{@value{AS}} maintains a counter of how many macros it has
4688 executed in this pseudo-variable; you can copy that number to your
4689 output with @samp{\@@}, but @emph{only within a macro definition}.
4692 @item LOCAL @var{name} [ , @dots{} ]
4693 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4694 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4695 Alternate macro syntax}.
4697 Generate a string replacement for each of the @var{name} arguments, and
4698 replace any instances of @var{name} in each macro expansion. The
4699 replacement string is unique in the assembly, and different for each
4700 separate macro expansion. @code{LOCAL} allows you to write macros that
4701 define symbols, without fear of conflict between separate macro expansions.
4706 @section @code{.nolist}
4708 @cindex @code{nolist} directive
4709 @cindex listing control, turning off
4710 Control (in conjunction with the @code{.list} directive) whether or
4711 not assembly listings are generated. These two directives maintain an
4712 internal counter (which is zero initially). @code{.list} increments the
4713 counter, and @code{.nolist} decrements it. Assembly listings are
4714 generated whenever the counter is greater than zero.
4717 @section @code{.octa @var{bignums}}
4719 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4720 @cindex @code{octa} directive
4721 @cindex integer, 16-byte
4722 @cindex sixteen byte integer
4723 This directive expects zero or more bignums, separated by commas. For each
4724 bignum, it emits a 16-byte integer.
4726 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4727 hence @emph{octa}-word for 16 bytes.
4730 @section @code{.org @var{new-lc} , @var{fill}}
4732 @cindex @code{org} directive
4733 @cindex location counter, advancing
4734 @cindex advancing location counter
4735 @cindex current address, advancing
4736 Advance the location counter of the current section to
4737 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4738 expression with the same section as the current subsection. That is,
4739 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4740 wrong section, the @code{.org} directive is ignored. To be compatible
4741 with former assemblers, if the section of @var{new-lc} is absolute,
4742 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4743 is the same as the current subsection.
4745 @code{.org} may only increase the location counter, or leave it
4746 unchanged; you cannot use @code{.org} to move the location counter
4749 @c double negative used below "not undefined" because this is a specific
4750 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4751 @c section. doc@cygnus.com 18feb91
4752 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4753 may not be undefined. If you really detest this restriction we eagerly await
4754 a chance to share your improved assembler.
4756 Beware that the origin is relative to the start of the section, not
4757 to the start of the subsection. This is compatible with other
4758 people's assemblers.
4760 When the location counter (of the current subsection) is advanced, the
4761 intervening bytes are filled with @var{fill} which should be an
4762 absolute expression. If the comma and @var{fill} are omitted,
4763 @var{fill} defaults to zero.
4766 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4768 @cindex padding the location counter given a power of two
4769 @cindex @code{p2align} directive
4770 Pad the location counter (in the current subsection) to a particular
4771 storage boundary. The first expression (which must be absolute) is the
4772 number of low-order zero bits the location counter must have after
4773 advancement. For example @samp{.p2align 3} advances the location
4774 counter until it a multiple of 8. If the location counter is already a
4775 multiple of 8, no change is needed.
4777 The second expression (also absolute) gives the fill value to be stored in the
4778 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4779 padding bytes are normally zero. However, on some systems, if the section is
4780 marked as containing code and the fill value is omitted, the space is filled
4781 with no-op instructions.
4783 The third expression is also absolute, and is also optional. If it is present,
4784 it is the maximum number of bytes that should be skipped by this alignment
4785 directive. If doing the alignment would require skipping more bytes than the
4786 specified maximum, then the alignment is not done at all. You can omit the
4787 fill value (the second argument) entirely by simply using two commas after the
4788 required alignment; this can be useful if you want the alignment to be filled
4789 with no-op instructions when appropriate.
4791 @cindex @code{p2alignw} directive
4792 @cindex @code{p2alignl} directive
4793 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4794 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4795 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4796 fill pattern as a four byte longword value. For example, @code{.p2alignw
4797 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4798 filled in with the value 0x368d (the exact placement of the bytes depends upon
4799 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4804 @section @code{.previous}
4806 @cindex @code{.previous} directive
4807 @cindex Section Stack
4808 This is one of the ELF section stack manipulation directives. The others are
4809 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4810 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4811 (@pxref{PopSection}).
4813 This directive swaps the current section (and subsection) with most recently
4814 referenced section (and subsection) prior to this one. Multiple
4815 @code{.previous} directives in a row will flip between two sections (and their
4818 In terms of the section stack, this directive swaps the current section with
4819 the top section on the section stack.
4824 @section @code{.popsection}
4826 @cindex @code{.popsection} directive
4827 @cindex Section Stack
4828 This is one of the ELF section stack manipulation directives. The others are
4829 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4830 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4833 This directive replaces the current section (and subsection) with the top
4834 section (and subsection) on the section stack. This section is popped off the
4839 @section @code{.print @var{string}}
4841 @cindex @code{print} directive
4842 @command{@value{AS}} will print @var{string} on the standard output during
4843 assembly. You must put @var{string} in double quotes.
4847 @section @code{.protected @var{names}}
4849 @cindex @code{.protected} directive
4851 This one of the ELF visibility directives. The other two are
4852 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4854 This directive overrides the named symbols default visibility (which is set by
4855 their binding: local, global or weak). The directive sets the visibility to
4856 @code{protected} which means that any references to the symbols from within the
4857 components that defines them must be resolved to the definition in that
4858 component, even if a definition in another component would normally preempt
4863 @section @code{.psize @var{lines} , @var{columns}}
4865 @cindex @code{psize} directive
4866 @cindex listing control: paper size
4867 @cindex paper size, for listings
4868 Use this directive to declare the number of lines---and, optionally, the
4869 number of columns---to use for each page, when generating listings.
4871 If you do not use @code{.psize}, listings use a default line-count
4872 of 60. You may omit the comma and @var{columns} specification; the
4873 default width is 200 columns.
4875 @command{@value{AS}} generates formfeeds whenever the specified number of
4876 lines is exceeded (or whenever you explicitly request one, using
4879 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4880 those explicitly specified with @code{.eject}.
4883 @section @code{.purgem @var{name}}
4885 @cindex @code{purgem} directive
4886 Undefine the macro @var{name}, so that later uses of the string will not be
4887 expanded. @xref{Macro}.
4891 @section @code{.pushsection @var{name} , @var{subsection}}
4893 @cindex @code{.pushsection} directive
4894 @cindex Section Stack
4895 This is one of the ELF section stack manipulation directives. The others are
4896 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4897 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4900 This directive is a synonym for @code{.section}. It pushes the current section
4901 (and subsection) onto the top of the section stack, and then replaces the
4902 current section and subsection with @code{name} and @code{subsection}.
4906 @section @code{.quad @var{bignums}}
4908 @cindex @code{quad} directive
4909 @code{.quad} expects zero or more bignums, separated by commas. For
4910 each bignum, it emits
4912 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4913 warning message; and just takes the lowest order 8 bytes of the bignum.
4914 @cindex eight-byte integer
4915 @cindex integer, 8-byte
4917 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4918 hence @emph{quad}-word for 8 bytes.
4921 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4922 warning message; and just takes the lowest order 16 bytes of the bignum.
4923 @cindex sixteen-byte integer
4924 @cindex integer, 16-byte
4928 @section @code{.rept @var{count}}
4930 @cindex @code{rept} directive
4931 Repeat the sequence of lines between the @code{.rept} directive and the next
4932 @code{.endr} directive @var{count} times.
4934 For example, assembling
4942 is equivalent to assembling
4951 @section @code{.sbttl "@var{subheading}"}
4953 @cindex @code{sbttl} directive
4954 @cindex subtitles for listings
4955 @cindex listing control: subtitle
4956 Use @var{subheading} as the title (third line, immediately after the
4957 title line) when generating assembly listings.
4959 This directive affects subsequent pages, as well as the current page if
4960 it appears within ten lines of the top of a page.
4964 @section @code{.scl @var{class}}
4966 @cindex @code{scl} directive
4967 @cindex symbol storage class (COFF)
4968 @cindex COFF symbol storage class
4969 Set the storage-class value for a symbol. This directive may only be
4970 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4971 whether a symbol is static or external, or it may record further
4972 symbolic debugging information.
4975 The @samp{.scl} directive is primarily associated with COFF output; when
4976 configured to generate @code{b.out} output format, @command{@value{AS}}
4977 accepts this directive but ignores it.
4982 @section @code{.section @var{name}} (COFF version)
4984 @cindex @code{section} directive
4985 @cindex named section
4986 Use the @code{.section} directive to assemble the following code into a section
4989 This directive is only supported for targets that actually support arbitrarily
4990 named sections; on @code{a.out} targets, for example, it is not accepted, even
4991 with a standard @code{a.out} section name.
4993 For COFF targets, the @code{.section} directive is used in one of the following
4997 .section @var{name}[, "@var{flags}"]
4998 .section @var{name}[, @var{subsegment}]
5001 If the optional argument is quoted, it is taken as flags to use for the
5002 section. Each flag is a single character. The following flags are recognized:
5005 bss section (uninitialized data)
5007 section is not loaded
5017 shared section (meaningful for PE targets)
5019 ignored. (For compatibility with the ELF version)
5022 If no flags are specified, the default flags depend upon the section name. If
5023 the section name is not recognized, the default will be for the section to be
5024 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5025 from the section, rather than adding them, so if they are used on their own it
5026 will be as if no flags had been specified at all.
5028 If the optional argument to the @code{.section} directive is not quoted, it is
5029 taken as a subsegment number (@pxref{Sub-Sections}).
5032 @section @code{.section @var{name}} (ELF version)
5034 @cindex @code{section} directive
5035 @cindex named section
5037 @cindex Section Stack
5038 This is one of the ELF section stack manipulation directives. The others are
5039 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5040 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5041 @code{.previous} (@pxref{Previous}).
5044 For ELF targets, the @code{.section} directive is used like this:
5047 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
5050 The optional @var{flags} argument is a quoted string which may contain any
5051 combination of the following characters:
5054 section is allocatable
5058 section is executable
5060 section is mergeable
5062 section contains zero terminated strings
5065 The optional @var{type} argument may contain one of the following constants:
5068 section contains data
5070 section does not contain data (i.e., section only occupies space)
5073 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5074 as well as @var{entsize} argument. Sections with @code{M} flag but not
5075 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5076 long. Sections with both @code{M} and @code{S} must contain zero terminated
5077 strings where each character is @var{entsize} bytes long. The linker may remove
5078 duplicates within sections with the same name, same entity size and same flags.
5080 If no flags are specified, the default flags depend upon the section name. If
5081 the section name is not recognized, the default will be for the section to have
5082 none of the above flags: it will not be allocated in memory, nor writable, nor
5083 executable. The section will contain data.
5085 For ELF targets, the assembler supports another type of @code{.section}
5086 directive for compatibility with the Solaris assembler:
5089 .section "@var{name}"[, @var{flags}...]
5092 Note that the section name is quoted. There may be a sequence of comma
5096 section is allocatable
5100 section is executable
5103 This directive replaces the current section and subsection. The replaced
5104 section and subsection are pushed onto the section stack. See the contents of
5105 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5106 how this directive and the other section stack directives work.
5109 @section @code{.set @var{symbol}, @var{expression}}
5111 @cindex @code{set} directive
5112 @cindex symbol value, setting
5113 Set the value of @var{symbol} to @var{expression}. This
5114 changes @var{symbol}'s value and type to conform to
5115 @var{expression}. If @var{symbol} was flagged as external, it remains
5116 flagged (@pxref{Symbol Attributes}).
5118 You may @code{.set} a symbol many times in the same assembly.
5120 If you @code{.set} a global symbol, the value stored in the object
5121 file is the last value stored into it.
5124 The syntax for @code{set} on the HPPA is
5125 @samp{@var{symbol} .set @var{expression}}.
5129 @section @code{.short @var{expressions}}
5131 @cindex @code{short} directive
5133 @code{.short} is normally the same as @samp{.word}.
5134 @xref{Word,,@code{.word}}.
5136 In some configurations, however, @code{.short} and @code{.word} generate
5137 numbers of different lengths; @pxref{Machine Dependencies}.
5141 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5144 This expects zero or more @var{expressions}, and emits
5145 a 16 bit number for each.
5150 @section @code{.single @var{flonums}}
5152 @cindex @code{single} directive
5153 @cindex floating point numbers (single)
5154 This directive assembles zero or more flonums, separated by commas. It
5155 has the same effect as @code{.float}.
5157 The exact kind of floating point numbers emitted depends on how
5158 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5162 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5163 numbers in @sc{ieee} format.
5168 @section @code{.size} (COFF version)
5170 @cindex @code{size} directive
5171 This directive is generated by compilers to include auxiliary debugging
5172 information in the symbol table. It is only permitted inside
5173 @code{.def}/@code{.endef} pairs.
5176 @samp{.size} is only meaningful when generating COFF format output; when
5177 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5181 @section @code{.size @var{name} , @var{expression}} (ELF version)
5182 @cindex @code{size} directive
5184 This directive is used to set the size associated with a symbol @var{name}.
5185 The size in bytes is computed from @var{expression} which can make use of label
5186 arithmetic. This directive is typically used to set the size of function
5190 @section @code{.sleb128 @var{expressions}}
5192 @cindex @code{sleb128} directive
5193 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5194 compact, variable length representation of numbers used by the DWARF
5195 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5197 @ifclear no-space-dir
5199 @section @code{.skip @var{size} , @var{fill}}
5201 @cindex @code{skip} directive
5202 @cindex filling memory
5203 This directive emits @var{size} bytes, each of value @var{fill}. Both
5204 @var{size} and @var{fill} are absolute expressions. If the comma and
5205 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5209 @section @code{.space @var{size} , @var{fill}}
5211 @cindex @code{space} directive
5212 @cindex filling memory
5213 This directive emits @var{size} bytes, each of value @var{fill}. Both
5214 @var{size} and @var{fill} are absolute expressions. If the comma
5215 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5220 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5221 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5222 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5223 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5232 @section @code{.space}
5233 @cindex @code{space} directive
5235 On the AMD 29K, this directive is ignored; it is accepted for
5236 compatibility with other AMD 29K assemblers.
5239 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5240 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5246 @section @code{.stabd, .stabn, .stabs}
5248 @cindex symbolic debuggers, information for
5249 @cindex @code{stab@var{x}} directives
5250 There are three directives that begin @samp{.stab}.
5251 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5252 The symbols are not entered in the @command{@value{AS}} hash table: they
5253 cannot be referenced elsewhere in the source file.
5254 Up to five fields are required:
5258 This is the symbol's name. It may contain any character except
5259 @samp{\000}, so is more general than ordinary symbol names. Some
5260 debuggers used to code arbitrarily complex structures into symbol names
5264 An absolute expression. The symbol's type is set to the low 8 bits of
5265 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5266 and debuggers choke on silly bit patterns.
5269 An absolute expression. The symbol's ``other'' attribute is set to the
5270 low 8 bits of this expression.
5273 An absolute expression. The symbol's descriptor is set to the low 16
5274 bits of this expression.
5277 An absolute expression which becomes the symbol's value.
5280 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5281 or @code{.stabs} statement, the symbol has probably already been created;
5282 you get a half-formed symbol in your object file. This is
5283 compatible with earlier assemblers!
5286 @cindex @code{stabd} directive
5287 @item .stabd @var{type} , @var{other} , @var{desc}
5289 The ``name'' of the symbol generated is not even an empty string.
5290 It is a null pointer, for compatibility. Older assemblers used a
5291 null pointer so they didn't waste space in object files with empty
5294 The symbol's value is set to the location counter,
5295 relocatably. When your program is linked, the value of this symbol
5296 is the address of the location counter when the @code{.stabd} was
5299 @cindex @code{stabn} directive
5300 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5301 The name of the symbol is set to the empty string @code{""}.
5303 @cindex @code{stabs} directive
5304 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5305 All five fields are specified.
5311 @section @code{.string} "@var{str}"
5313 @cindex string, copying to object file
5314 @cindex @code{string} directive
5316 Copy the characters in @var{str} to the object file. You may specify more than
5317 one string to copy, separated by commas. Unless otherwise specified for a
5318 particular machine, the assembler marks the end of each string with a 0 byte.
5319 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5322 @section @code{.struct @var{expression}}
5324 @cindex @code{struct} directive
5325 Switch to the absolute section, and set the section offset to @var{expression},
5326 which must be an absolute expression. You might use this as follows:
5335 This would define the symbol @code{field1} to have the value 0, the symbol
5336 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5337 value 8. Assembly would be left in the absolute section, and you would need to
5338 use a @code{.section} directive of some sort to change to some other section
5339 before further assembly.
5343 @section @code{.subsection @var{name}}
5345 @cindex @code{.subsection} directive
5346 @cindex Section Stack
5347 This is one of the ELF section stack manipulation directives. The others are
5348 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5349 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5352 This directive replaces the current subsection with @code{name}. The current
5353 section is not changed. The replaced subsection is put onto the section stack
5354 in place of the then current top of stack subsection.
5359 @section @code{.symver}
5360 @cindex @code{symver} directive
5361 @cindex symbol versioning
5362 @cindex versions of symbols
5363 Use the @code{.symver} directive to bind symbols to specific version nodes
5364 within a source file. This is only supported on ELF platforms, and is
5365 typically used when assembling files to be linked into a shared library.
5366 There are cases where it may make sense to use this in objects to be bound
5367 into an application itself so as to override a versioned symbol from a
5370 For ELF targets, the @code{.symver} directive can be used like this:
5372 .symver @var{name}, @var{name2@@nodename}
5374 If the symbol @var{name} is defined within the file
5375 being assembled, the @code{.symver} directive effectively creates a symbol
5376 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5377 just don't try and create a regular alias is that the @var{@@} character isn't
5378 permitted in symbol names. The @var{name2} part of the name is the actual name
5379 of the symbol by which it will be externally referenced. The name @var{name}
5380 itself is merely a name of convenience that is used so that it is possible to
5381 have definitions for multiple versions of a function within a single source
5382 file, and so that the compiler can unambiguously know which version of a
5383 function is being mentioned. The @var{nodename} portion of the alias should be
5384 the name of a node specified in the version script supplied to the linker when
5385 building a shared library. If you are attempting to override a versioned
5386 symbol from a shared library, then @var{nodename} should correspond to the
5387 nodename of the symbol you are trying to override.
5389 If the symbol @var{name} is not defined within the file being assembled, all
5390 references to @var{name} will be changed to @var{name2@@nodename}. If no
5391 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5394 Another usage of the @code{.symver} directive is:
5396 .symver @var{name}, @var{name2@@@@nodename}
5398 In this case, the symbol @var{name} must exist and be defined within
5399 the file being assembled. It is similar to @var{name2@@nodename}. The
5400 difference is @var{name2@@@@nodename} will also be used to resolve
5401 references to @var{name2} by the linker.
5403 The third usage of the @code{.symver} directive is:
5405 .symver @var{name}, @var{name2@@@@@@nodename}
5407 When @var{name} is not defined within the
5408 file being assembled, it is treated as @var{name2@@nodename}. When
5409 @var{name} is defined within the file being assembled, the symbol
5410 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5415 @section @code{.tag @var{structname}}
5417 @cindex COFF structure debugging
5418 @cindex structure debugging, COFF
5419 @cindex @code{tag} directive
5420 This directive is generated by compilers to include auxiliary debugging
5421 information in the symbol table. It is only permitted inside
5422 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5423 definitions in the symbol table with instances of those structures.
5426 @samp{.tag} is only used when generating COFF format output; when
5427 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5433 @section @code{.text @var{subsection}}
5435 @cindex @code{text} directive
5436 Tells @command{@value{AS}} to assemble the following statements onto the end of
5437 the text subsection numbered @var{subsection}, which is an absolute
5438 expression. If @var{subsection} is omitted, subsection number zero
5442 @section @code{.title "@var{heading}"}
5444 @cindex @code{title} directive
5445 @cindex listing control: title line
5446 Use @var{heading} as the title (second line, immediately after the
5447 source file name and pagenumber) when generating assembly listings.
5449 This directive affects subsequent pages, as well as the current page if
5450 it appears within ten lines of the top of a page.
5453 @section @code{.type @var{int}} (COFF version)
5455 @cindex COFF symbol type
5456 @cindex symbol type, COFF
5457 @cindex @code{type} directive
5458 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5459 records the integer @var{int} as the type attribute of a symbol table entry.
5462 @samp{.type} is associated only with COFF format output; when
5463 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5464 directive but ignores it.
5467 @section @code{.type @var{name} , @var{type description}} (ELF version)
5469 @cindex ELF symbol type
5470 @cindex symbol type, ELF
5471 @cindex @code{type} directive
5472 This directive is used to set the type of symbol @var{name} to be either a
5473 function symbol or an object symbol. There are five different syntaxes
5474 supported for the @var{type description} field, in order to provide
5475 compatibility with various other assemblers. The syntaxes supported are:
5478 .type <name>,#function
5479 .type <name>,#object
5481 .type <name>,@@function
5482 .type <name>,@@object
5484 .type <name>,%function
5485 .type <name>,%object
5487 .type <name>,"function"
5488 .type <name>,"object"
5490 .type <name> STT_FUNCTION
5491 .type <name> STT_OBJECT
5495 @section @code{.uleb128 @var{expressions}}
5497 @cindex @code{uleb128} directive
5498 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5499 compact, variable length representation of numbers used by the DWARF
5500 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5504 @section @code{.val @var{addr}}
5506 @cindex @code{val} directive
5507 @cindex COFF value attribute
5508 @cindex value attribute, COFF
5509 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5510 records the address @var{addr} as the value attribute of a symbol table
5514 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5515 configured for @code{b.out}, it accepts this directive but ignores it.
5521 @section @code{.version "@var{string}"}
5523 @cindex @code{.version}
5524 This directive creates a @code{.note} section and places into it an ELF
5525 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5530 @section @code{.vtable_entry @var{table}, @var{offset}}
5532 @cindex @code{.vtable_entry}
5533 This directive finds or creates a symbol @code{table} and creates a
5534 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5537 @section @code{.vtable_inherit @var{child}, @var{parent}}
5539 @cindex @code{.vtable_inherit}
5540 This directive finds the symbol @code{child} and finds or creates the symbol
5541 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5542 parent whose addend is the value of the child symbol. As a special case the
5543 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5548 @section @code{.weak @var{names}}
5550 @cindex @code{.weak}
5551 This directive sets the weak attribute on the comma separated list of symbol
5552 @code{names}. If the symbols do not already exist, they will be created.
5556 @section @code{.word @var{expressions}}
5558 @cindex @code{word} directive
5559 This directive expects zero or more @var{expressions}, of any section,
5560 separated by commas.
5563 For each expression, @command{@value{AS}} emits a 32-bit number.
5566 For each expression, @command{@value{AS}} emits a 16-bit number.
5571 The size of the number emitted, and its byte order,
5572 depend on what target computer the assembly is for.
5575 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5576 @c happen---32-bit addressability, period; no long/short jumps.
5577 @ifset DIFF-TBL-KLUGE
5578 @cindex difference tables altered
5579 @cindex altered difference tables
5581 @emph{Warning: Special Treatment to support Compilers}
5585 Machines with a 32-bit address space, but that do less than 32-bit
5586 addressing, require the following special treatment. If the machine of
5587 interest to you does 32-bit addressing (or doesn't require it;
5588 @pxref{Machine Dependencies}), you can ignore this issue.
5591 In order to assemble compiler output into something that works,
5592 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5593 Directives of the form @samp{.word sym1-sym2} are often emitted by
5594 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5595 directive of the form @samp{.word sym1-sym2}, and the difference between
5596 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5597 creates a @dfn{secondary jump table}, immediately before the next label.
5598 This secondary jump table is preceded by a short-jump to the
5599 first byte after the secondary table. This short-jump prevents the flow
5600 of control from accidentally falling into the new table. Inside the
5601 table is a long-jump to @code{sym2}. The original @samp{.word}
5602 contains @code{sym1} minus the address of the long-jump to
5605 If there were several occurrences of @samp{.word sym1-sym2} before the
5606 secondary jump table, all of them are adjusted. If there was a
5607 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5608 long-jump to @code{sym4} is included in the secondary jump table,
5609 and the @code{.word} directives are adjusted to contain @code{sym3}
5610 minus the address of the long-jump to @code{sym4}; and so on, for as many
5611 entries in the original jump table as necessary.
5614 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5615 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5616 assembly language programmers.
5619 @c end DIFF-TBL-KLUGE
5622 @section Deprecated Directives
5624 @cindex deprecated directives
5625 @cindex obsolescent directives
5626 One day these directives won't work.
5627 They are included for compatibility with older assemblers.
5634 @node Machine Dependencies
5635 @chapter Machine Dependent Features
5637 @cindex machine dependencies
5638 The machine instruction sets are (almost by definition) different on
5639 each machine where @command{@value{AS}} runs. Floating point representations
5640 vary as well, and @command{@value{AS}} often supports a few additional
5641 directives or command-line options for compatibility with other
5642 assemblers on a particular platform. Finally, some versions of
5643 @command{@value{AS}} support special pseudo-instructions for branch
5646 This chapter discusses most of these differences, though it does not
5647 include details on any machine's instruction set. For details on that
5648 subject, see the hardware manufacturer's manual.
5652 * AMD29K-Dependent:: AMD 29K Dependent Features
5655 * Alpha-Dependent:: Alpha Dependent Features
5658 * ARC-Dependent:: ARC Dependent Features
5661 * ARM-Dependent:: ARM Dependent Features
5664 * CRIS-Dependent:: CRIS Dependent Features
5667 * D10V-Dependent:: D10V Dependent Features
5670 * D30V-Dependent:: D30V Dependent Features
5673 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5676 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5679 * HPPA-Dependent:: HPPA Dependent Features
5682 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5685 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5688 * i860-Dependent:: Intel 80860 Dependent Features
5691 * i960-Dependent:: Intel 80960 Dependent Features
5694 * M32R-Dependent:: M32R Dependent Features
5697 * M68K-Dependent:: M680x0 Dependent Features
5700 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5703 * M88K-Dependent:: M880x0 Dependent Features
5706 * MIPS-Dependent:: MIPS Dependent Features
5709 * MMIX-Dependent:: MMIX Dependent Features
5712 * SH-Dependent:: Hitachi SH Dependent Features
5713 * SH64-Dependent:: Hitachi SH64 Dependent Features
5716 * PDP-11-Dependent:: PDP-11 Dependent Features
5719 * PJ-Dependent:: picoJava Dependent Features
5722 * PPC-Dependent:: PowerPC Dependent Features
5725 * Sparc-Dependent:: SPARC Dependent Features
5728 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5731 * V850-Dependent:: V850 Dependent Features
5734 * Z8000-Dependent:: Z8000 Dependent Features
5737 * Vax-Dependent:: VAX Dependent Features
5744 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5745 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5746 @c peculiarity: to preserve cross-references, there must be a node called
5747 @c "Machine Dependencies". Hence the conditional nodenames in each
5748 @c major node below. Node defaulting in makeinfo requires adjacency of
5749 @c node and sectioning commands; hence the repetition of @chapter BLAH
5750 @c in both conditional blocks.
5753 @include c-a29k.texi
5757 @include c-alpha.texi
5769 @include c-cris.texi
5774 @node Machine Dependencies
5775 @chapter Machine Dependent Features
5777 The machine instruction sets are different on each Hitachi chip family,
5778 and there are also some syntax differences among the families. This
5779 chapter describes the specific @command{@value{AS}} features for each
5783 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5784 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5785 * SH-Dependent:: Hitachi SH Dependent Features
5792 @include c-d10v.texi
5796 @include c-d30v.texi
5800 @include c-h8300.texi
5804 @include c-h8500.texi
5808 @include c-hppa.texi
5812 @include c-i370.texi
5816 @include c-i386.texi
5820 @include c-i860.texi
5824 @include c-i960.texi
5828 @include c-ia64.texi
5832 @include c-m32r.texi
5836 @include c-m68k.texi
5840 @include c-m68hc11.texi
5844 @include c-m88k.texi
5848 @include c-mips.texi
5852 @include c-mmix.texi
5856 @include c-ns32k.texi
5860 @include c-pdp11.texi
5873 @include c-sh64.texi
5877 @include c-sparc.texi
5881 @include c-tic54x.texi
5893 @include c-v850.texi
5897 @c reverse effect of @down at top of generic Machine-Dep chapter
5901 @node Reporting Bugs
5902 @chapter Reporting Bugs
5903 @cindex bugs in assembler
5904 @cindex reporting bugs in assembler
5906 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5908 Reporting a bug may help you by bringing a solution to your problem, or it may
5909 not. But in any case the principal function of a bug report is to help the
5910 entire community by making the next version of @command{@value{AS}} work better.
5911 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5913 In order for a bug report to serve its purpose, you must include the
5914 information that enables us to fix the bug.
5917 * Bug Criteria:: Have you found a bug?
5918 * Bug Reporting:: How to report bugs
5922 @section Have you found a bug?
5923 @cindex bug criteria
5925 If you are not sure whether you have found a bug, here are some guidelines:
5928 @cindex fatal signal
5929 @cindex assembler crash
5930 @cindex crash of assembler
5932 If the assembler gets a fatal signal, for any input whatever, that is a
5933 @command{@value{AS}} bug. Reliable assemblers never crash.
5935 @cindex error on valid input
5937 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5939 @cindex invalid input
5941 If @command{@value{AS}} does not produce an error message for invalid input, that
5942 is a bug. However, you should note that your idea of ``invalid input'' might
5943 be our idea of ``an extension'' or ``support for traditional practice''.
5946 If you are an experienced user of assemblers, your suggestions for improvement
5947 of @command{@value{AS}} are welcome in any case.
5951 @section How to report bugs
5953 @cindex assembler bugs, reporting
5955 A number of companies and individuals offer support for @sc{gnu} products. If
5956 you obtained @command{@value{AS}} from a support organization, we recommend you
5957 contact that organization first.
5959 You can find contact information for many support companies and
5960 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5963 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5964 to @samp{bug-binutils@@gnu.org}.
5966 The fundamental principle of reporting bugs usefully is this:
5967 @strong{report all the facts}. If you are not sure whether to state a
5968 fact or leave it out, state it!
5970 Often people omit facts because they think they know what causes the problem
5971 and assume that some details do not matter. Thus, you might assume that the
5972 name of a symbol you use in an example does not matter. Well, probably it does
5973 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5974 happens to fetch from the location where that name is stored in memory;
5975 perhaps, if the name were different, the contents of that location would fool
5976 the assembler into doing the right thing despite the bug. Play it safe and
5977 give a specific, complete example. That is the easiest thing for you to do,
5978 and the most helpful.
5980 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5981 it is new to us. Therefore, always write your bug reports on the assumption
5982 that the bug has not been reported previously.
5984 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5985 bell?'' Those bug reports are useless, and we urge everyone to
5986 @emph{refuse to respond to them} except to chide the sender to report
5989 To enable us to fix the bug, you should include all these things:
5993 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5994 it with the @samp{--version} argument.
5996 Without this, we will not know whether there is any point in looking for
5997 the bug in the current version of @command{@value{AS}}.
6000 Any patches you may have applied to the @command{@value{AS}} source.
6003 The type of machine you are using, and the operating system name and
6007 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6011 The command arguments you gave the assembler to assemble your example and
6012 observe the bug. To guarantee you will not omit something important, list them
6013 all. A copy of the Makefile (or the output from make) is sufficient.
6015 If we were to try to guess the arguments, we would probably guess wrong
6016 and then we might not encounter the bug.
6019 A complete input file that will reproduce the bug. If the bug is observed when
6020 the assembler is invoked via a compiler, send the assembler source, not the
6021 high level language source. Most compilers will produce the assembler source
6022 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6023 the options @samp{-v --save-temps}; this will save the assembler source in a
6024 file with an extension of @file{.s}, and also show you exactly how
6025 @command{@value{AS}} is being run.
6028 A description of what behavior you observe that you believe is
6029 incorrect. For example, ``It gets a fatal signal.''
6031 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6032 will certainly notice it. But if the bug is incorrect output, we might not
6033 notice unless it is glaringly wrong. You might as well not give us a chance to
6036 Even if the problem you experience is a fatal signal, you should still say so
6037 explicitly. Suppose something strange is going on, such as, your copy of
6038 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6039 library on your system. (This has happened!) Your copy might crash and ours
6040 would not. If you told us to expect a crash, then when ours fails to crash, we
6041 would know that the bug was not happening for us. If you had not told us to
6042 expect a crash, then we would not be able to draw any conclusion from our
6046 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6047 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6048 option. Always send diffs from the old file to the new file. If you even
6049 discuss something in the @command{@value{AS}} source, refer to it by context, not
6052 The line numbers in our development sources will not match those in your
6053 sources. Your line numbers would convey no useful information to us.
6056 Here are some things that are not necessary:
6060 A description of the envelope of the bug.
6062 Often people who encounter a bug spend a lot of time investigating
6063 which changes to the input file will make the bug go away and which
6064 changes will not affect it.
6066 This is often time consuming and not very useful, because the way we
6067 will find the bug is by running a single example under the debugger
6068 with breakpoints, not by pure deduction from a series of examples.
6069 We recommend that you save your time for something else.
6071 Of course, if you can find a simpler example to report @emph{instead}
6072 of the original one, that is a convenience for us. Errors in the
6073 output will be easier to spot, running under the debugger will take
6074 less time, and so on.
6076 However, simplification is not vital; if you do not want to do this,
6077 report the bug anyway and send us the entire test case you used.
6080 A patch for the bug.
6082 A patch for the bug does help us if it is a good one. But do not omit
6083 the necessary information, such as the test case, on the assumption that
6084 a patch is all we need. We might see problems with your patch and decide
6085 to fix the problem another way, or we might not understand it at all.
6087 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6088 construct an example that will make the program follow a certain path through
6089 the code. If you do not send us the example, we will not be able to construct
6090 one, so we will not be able to verify that the bug is fixed.
6092 And if we cannot understand what bug you are trying to fix, or why your
6093 patch should be an improvement, we will not install it. A test case will
6094 help us to understand.
6097 A guess about what the bug is or what it depends on.
6099 Such guesses are usually wrong. Even we cannot guess right about such
6100 things without first using the debugger to find the facts.
6103 @node Acknowledgements
6104 @chapter Acknowledgements
6106 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6107 it is not meant as a slight. We just don't know about it. Send mail to the
6108 maintainer, and we'll correct the situation. Currently
6110 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6112 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6115 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6116 information and the 68k series machines, most of the preprocessing pass, and
6117 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6119 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6120 many bug fixes, including merging support for several processors, breaking GAS
6121 up to handle multiple object file format back ends (including heavy rewrite,
6122 testing, an integration of the coff and b.out back ends), adding configuration
6123 including heavy testing and verification of cross assemblers and file splits
6124 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6125 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6126 port (including considerable amounts of reverse engineering), a SPARC opcode
6127 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6128 assertions and made them work, much other reorganization, cleanup, and lint.
6130 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6131 in format-specific I/O modules.
6133 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6134 has done much work with it since.
6136 The Intel 80386 machine description was written by Eliot Dresselhaus.
6138 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6140 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6141 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6143 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6144 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6145 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6146 support a.out format.
6148 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6149 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6150 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6151 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6154 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6155 simplified the configuration of which versions accept which directives. He
6156 updated the 68k machine description so that Motorola's opcodes always produced
6157 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6158 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6159 cross-compilation support, and one bug in relaxation that took a week and
6160 required the proverbial one-bit fix.
6162 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6163 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6164 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6165 PowerPC assembler, and made a few other minor patches.
6167 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6169 Hewlett-Packard contributed support for the HP9000/300.
6171 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6172 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6173 formats). This work was supported by both the Center for Software Science at
6174 the University of Utah and Cygnus Support.
6176 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6177 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6178 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6179 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6180 and some initial 64-bit support).
6182 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6184 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6185 support for openVMS/Alpha.
6187 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6190 Several engineers at Cygnus Support have also provided many small bug fixes and
6191 configuration enhancements.
6193 Many others have contributed large or small bugfixes and enhancements. If
6194 you have contributed significant work and are not mentioned on this list, and
6195 want to be, let us know. Some of the history has been lost; we are not
6196 intentionally leaving anyone out.
6198 @node GNU Free Documentation License
6199 @chapter GNU Free Documentation License
6201 GNU Free Documentation License
6203 Version 1.1, March 2000
6205 Copyright (C) 2000 Free Software Foundation, Inc.
6206 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6208 Everyone is permitted to copy and distribute verbatim copies
6209 of this license document, but changing it is not allowed.
6214 The purpose of this License is to make a manual, textbook, or other
6215 written document "free" in the sense of freedom: to assure everyone
6216 the effective freedom to copy and redistribute it, with or without
6217 modifying it, either commercially or noncommercially. Secondarily,
6218 this License preserves for the author and publisher a way to get
6219 credit for their work, while not being considered responsible for
6220 modifications made by others.
6222 This License is a kind of "copyleft", which means that derivative
6223 works of the document must themselves be free in the same sense. It
6224 complements the GNU General Public License, which is a copyleft
6225 license designed for free software.
6227 We have designed this License in order to use it for manuals for free
6228 software, because free software needs free documentation: a free
6229 program should come with manuals providing the same freedoms that the
6230 software does. But this License is not limited to software manuals;
6231 it can be used for any textual work, regardless of subject matter or
6232 whether it is published as a printed book. We recommend this License
6233 principally for works whose purpose is instruction or reference.
6236 1. APPLICABILITY AND DEFINITIONS
6238 This License applies to any manual or other work that contains a
6239 notice placed by the copyright holder saying it can be distributed
6240 under the terms of this License. The "Document", below, refers to any
6241 such manual or work. Any member of the public is a licensee, and is
6244 A "Modified Version" of the Document means any work containing the
6245 Document or a portion of it, either copied verbatim, or with
6246 modifications and/or translated into another language.
6248 A "Secondary Section" is a named appendix or a front-matter section of
6249 the Document that deals exclusively with the relationship of the
6250 publishers or authors of the Document to the Document's overall subject
6251 (or to related matters) and contains nothing that could fall directly
6252 within that overall subject. (For example, if the Document is in part a
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6254 mathematics.) The relationship could be a matter of historical
6255 connection with the subject or with related matters, or of legal,
6256 commercial, philosophical, ethical or political position regarding
6259 The "Invariant Sections" are certain Secondary Sections whose titles
6260 are designated, as being those of Invariant Sections, in the notice
6261 that says that the Document is released under this License.
6263 The "Cover Texts" are certain short passages of text that are listed,
6264 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6265 the Document is released under this License.
6267 A "Transparent" copy of the Document means a machine-readable copy,
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6274 to text formatters. A copy made in an otherwise Transparent file
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6279 Examples of suitable formats for Transparent copies include plain
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6286 machine-generated HTML produced by some word processors for output
6289 The "Title Page" means, for a printed book, the title page itself,
6290 plus such following pages as are needed to hold, legibly, the material
6291 this License requires to appear in the title page. For works in
6292 formats which do not have any title page as such, "Title Page" means
6293 the text near the most prominent appearance of the work's title,
6294 preceding the beginning of the body of the text.
6299 You may copy and distribute the Document in any medium, either
6300 commercially or noncommercially, provided that this License, the
6301 copyright notices, and the license notice saying this License applies
6302 to the Document are reproduced in all copies, and that you add no other
6303 conditions whatsoever to those of this License. You may not use
6304 technical measures to obstruct or control the reading or further
6305 copying of the copies you make or distribute. However, you may accept
6306 compensation in exchange for copies. If you distribute a large enough
6307 number of copies you must also follow the conditions in section 3.
6309 You may also lend copies, under the same conditions stated above, and
6310 you may publicly display copies.
6313 3. COPYING IN QUANTITY
6315 If you publish printed copies of the Document numbering more than 100,
6316 and the Document's license notice requires Cover Texts, you must enclose
6317 the copies in covers that carry, clearly and legibly, all these Cover
6318 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6319 the back cover. Both covers must also clearly and legibly identify
6320 you as the publisher of these copies. The front cover must present
6321 the full title with all words of the title equally prominent and
6322 visible. You may add other material on the covers in addition.
6323 Copying with changes limited to the covers, as long as they preserve
6324 the title of the Document and satisfy these conditions, can be treated
6325 as verbatim copying in other respects.
6327 If the required texts for either cover are too voluminous to fit
6328 legibly, you should put the first ones listed (as many as fit
6329 reasonably) on the actual cover, and continue the rest onto adjacent
6332 If you publish or distribute Opaque copies of the Document numbering
6333 more than 100, you must either include a machine-readable Transparent
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6335 a publicly-accessible computer-network location containing a complete
6336 Transparent copy of the Document, free of added material, which the
6337 general network-using public has access to download anonymously at no
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6340 distribution of Opaque copies in quantity, to ensure that this
6341 Transparent copy will remain thus accessible at the stated location
6342 until at least one year after the last time you distribute an Opaque
6343 copy (directly or through your agents or retailers) of that edition to
6346 It is requested, but not required, that you contact the authors of the
6347 Document well before redistributing any large number of copies, to give
6348 them a chance to provide you with an updated version of the Document.
6353 You may copy and distribute a Modified Version of the Document under
6354 the conditions of sections 2 and 3 above, provided that you release
6355 the Modified Version under precisely this License, with the Modified
6356 Version filling the role of the Document, thus licensing distribution
6357 and modification of the Modified Version to whoever possesses a copy
6358 of it. In addition, you must do these things in the Modified Version:
6360 A. Use in the Title Page (and on the covers, if any) a title distinct
6361 from that of the Document, and from those of previous versions
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6365 B. List on the Title Page, as authors, one or more persons or entities
6366 responsible for authorship of the modifications in the Modified
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6368 Document (all of its principal authors, if it has less than five).
6369 C. State on the Title page the name of the publisher of the
6370 Modified Version, as the publisher.
6371 D. Preserve all the copyright notices of the Document.
6372 E. Add an appropriate copyright notice for your modifications
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6374 F. Include, immediately after the copyright notices, a license notice
6375 giving the public permission to use the Modified Version under the
6376 terms of this License, in the form shown in the Addendum below.
6377 G. Preserve in that license notice the full lists of Invariant Sections
6378 and required Cover Texts given in the Document's license notice.
6379 H. Include an unaltered copy of this License.
6380 I. Preserve the section entitled "History", and its title, and add to
6381 it an item stating at least the title, year, new authors, and
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6383 there is no section entitled "History" in the Document, create one
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6387 J. Preserve the network location, if any, given in the Document for
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6394 K. In any section entitled "Acknowledgements" or "Dedications",
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6396 substance and tone of each of the contributor acknowledgements
6397 and/or dedications given therein.
6398 L. Preserve all the Invariant Sections of the Document,
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6401 M. Delete any section entitled "Endorsements". Such a section
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6403 N. Do not retitle any existing section as "Endorsements"
6404 or to conflict in title with any Invariant Section.
6406 If the Modified Version includes new front-matter sections or
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6409 of these sections as invariant. To do this, add their titles to the
6410 list of Invariant Sections in the Modified Version's license notice.
6411 These titles must be distinct from any other section titles.
6413 You may add a section entitled "Endorsements", provided it contains
6414 nothing but endorsements of your Modified Version by various
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6416 been approved by an organization as the authoritative definition of a
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6420 passage of up to 25 words as a Back-Cover Text, to the end of the list
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6427 permission from the previous publisher that added the old one.
6429 The author(s) and publisher(s) of the Document do not by this License
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6434 5. COMBINING DOCUMENTS
6436 You may combine the Document with other documents released under this
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6439 Invariant Sections of all of the original documents, unmodified, and
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6449 Make the same adjustment to the section titles in the list of
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6452 In the combination, you must combine any sections entitled "History"
6453 in the various original documents, forming one section entitled
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6456 entitled "Endorsements."
6459 6. COLLECTIONS OF DOCUMENTS
6461 You may make a collection consisting of the Document and other documents
6462 released under this License, and replace the individual copies of this
6463 License in the various documents with a single copy that is included in
6464 the collection, provided that you follow the rules of this License for
6465 verbatim copying of each of the documents in all other respects.
6467 You may extract a single document from such a collection, and distribute
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6470 other respects regarding verbatim copying of that document.
6473 7. AGGREGATION WITH INDEPENDENT WORKS
6475 A compilation of the Document or its derivatives with other separate
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6477 distribution medium, does not as a whole count as a Modified Version
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6479 compilation. Such a compilation is called an "aggregate", and this
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6484 If the Cover Text requirement of section 3 is applicable to these
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6493 Translation is considered a kind of modification, so you may
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6498 original versions of these Invariant Sections. You may include a
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6501 between the translation and the original English version of this
6502 License, the original English version will prevail.
6507 You may not copy, modify, sublicense, or distribute the Document except
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6510 automatically terminate your rights under this License. However,
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6513 parties remain in full compliance.
6516 10. FUTURE REVISIONS OF THIS LICENSE
6518 The Free Software Foundation may publish new, revised versions
6519 of the GNU Free Documentation License from time to time. Such new
6520 versions will be similar in spirit to the present version, but may
6521 differ in detail to address new problems or concerns. See
6522 http://www.gnu.org/copyleft/.
6524 Each version of the License is given a distinguishing version number.
6525 If the Document specifies that a particular numbered version of this
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6529 Free Software Foundation. If the Document does not specify a version
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6534 ADDENDUM: How to use this License for your documents
6536 To use this License in a document you have written, include a copy of
6537 the License in the document and put the following copyright and
6538 license notices just after the title page:
6541 Copyright (c) YEAR YOUR NAME.
6542 Permission is granted to copy, distribute and/or modify this document
6543 under the terms of the GNU Free Documentation License, Version 1.1
6544 or any later version published by the Free Software Foundation;
6545 with the Invariant Sections being LIST THEIR TITLES, with the
6546 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6547 A copy of the license is included in the section entitled "GNU
6548 Free Documentation License".
6551 If you have no Invariant Sections, write "with no Invariant Sections"
6552 instead of saying which ones are invariant. If you have no
6553 Front-Cover Texts, write "no Front-Cover Texts" instead of
6554 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6556 If your document contains nontrivial examples of program code, we
6557 recommend releasing these examples in parallel under your choice of
6558 free software license, such as the GNU General Public License,
6559 to permit their use in free software.
projects / deliverable / binutils-gdb.git / blob