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
60 @c common OR combinations of conditions
80 @set abnormal-separator
84 @settitle Using @value{AS}
87 @settitle Using @value{AS} (@value{TARGET})
89 @setchapternewpage odd
94 @c WARE! Some of the machine-dependent sections contain tables of machine
95 @c instructions. Except in multi-column format, these tables look silly.
96 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
97 @c the multi-col format is faked within @example sections.
99 @c Again unfortunately, the natural size that fits on a page, for these tables,
100 @c is different depending on whether or not smallbook is turned on.
101 @c This matters, because of order: text flow switches columns at each page
104 @c The format faked in this source works reasonably well for smallbook,
105 @c not well for the default large-page format. This manual expects that if you
106 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
107 @c tables in question. You can turn on one without the other at your
108 @c discretion, of course.
111 @c the insn tables look just as silly in info files regardless of smallbook,
112 @c might as well show 'em anyways.
118 * As: (as). The GNU assembler.
127 This file documents the GNU Assembler "@value{AS}".
129 @c man begin COPYRIGHT
130 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
132 Permission is granted to copy, distribute and/or modify this document
133 under the terms of the GNU Free Documentation License, Version 1.1
134 or any later version published by the Free Software Foundation;
135 with no Invariant Sections, with no Front-Cover Texts, and with no
136 Back-Cover Texts. A copy of the license is included in the
137 section entitled "GNU Free Documentation License".
142 Permission is granted to process this file through Tex and print the
143 results, provided the printed document carries copying permission
144 notice identical to this one except for the removal of this paragraph
145 (this paragraph not being relevant to the printed manual).
151 @title Using @value{AS}
152 @subtitle The @sc{gnu} Assembler
154 @subtitle for the @value{TARGET} family
157 @subtitle Version @value{VERSION}
160 The Free Software Foundation Inc. thanks The Nice Computer
161 Company of Australia for loaning Dean Elsner to write the
162 first (Vax) version of @command{as} for Project @sc{gnu}.
163 The proprietors, management and staff of TNCCA thank FSF for
164 distracting the boss while they got some work
167 @author Dean Elsner, Jay Fenlason & friends
171 \hfill {\it Using {\tt @value{AS}}}\par
172 \hfill Edited by Cygnus Support\par
174 %"boxit" macro for figures:
175 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
176 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
177 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
178 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
179 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
182 @vskip 0pt plus 1filll
183 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
185 Permission is granted to copy, distribute and/or modify this document
186 under the terms of the GNU Free Documentation License, Version 1.1
187 or any later version published by the Free Software Foundation;
188 with no Invariant Sections, with no Front-Cover Texts, and with no
189 Back-Cover Texts. A copy of the license is included in the
190 section entitled "GNU Free Documentation License".
196 @top Using @value{AS}
198 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
201 This version of the file describes @command{@value{AS}} configured to generate
202 code for @value{TARGET} architectures.
205 This document is distributed under the terms of the GNU Free
206 Documentation License. A copy of the license is included in the
207 section entitled "GNU Free Documentation License".
210 * Overview:: Overview
211 * Invoking:: Command-Line Options
213 * Sections:: Sections and Relocation
215 * Expressions:: Expressions
216 * Pseudo Ops:: Assembler Directives
217 * Machine Dependencies:: Machine Dependent Features
218 * Reporting Bugs:: Reporting Bugs
219 * Acknowledgements:: Who Did What
220 * GNU Free Documentation License:: GNU Free Documentation License
228 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
230 This version of the manual describes @command{@value{AS}} configured to generate
231 code for @value{TARGET} architectures.
235 @cindex invocation summary
236 @cindex option summary
237 @cindex summary of options
238 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
239 @pxref{Invoking,,Comand-Line Options}.
241 @c man title AS the portable GNU assembler.
245 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
249 @c We don't use deffn and friends for the following because they seem
250 @c to be limited to one line for the header.
252 @c man begin SYNOPSIS
253 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
254 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
255 [@b{-J}] [@b{-K}] [@b{-L}]
256 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
257 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
258 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
259 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
260 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
261 [@b{--}|@var{files} @dots{}]
263 @c Target dependent options are listed below. Keep the list sorted.
264 @c Add an empty line for separation.
266 @c am29k has no machine-dependent assembler options
270 @emph{Target ARC options:}
276 @emph{Target ARM options:}
277 [@b{-m[arm]1}|@b{-m[arm]2}|@b{-m[arm]250}|@b{-m[arm]3}|
278 @b{-m[arm]6}|@b{-m[arm]60}|@b{-m[arm]600}|@b{-m[arm]610}|
279 @b{-m[arm]620}|@b{-m[arm]7[t][[d]m[i]][fe]}|@b{-m[arm]70}|
280 @b{-m[arm]700}|@b{-m[arm]710[c]}|@b{-m[arm]7100}|
281 @b{-m[arm]7500}|@b{-m[arm]8}|@b{-m[arm]810}|@b{-m[arm]9}|
282 @b{-m[arm]920}|@b{-m[arm]920t}|@b{-m[arm]9tdmi}|
283 @b{-mstrongarm}|@b{-mstrongarm110}|@b{-mstrongarm1100}]
284 [@b{-m[arm]v2}|@b{-m[arm]v2a}|@b{-m[arm]v3}|@b{-m[arm]v3m}|
285 @b{-m[arm]v4}|@b{-m[arm]v4t}|@b{-m[arm]v5}|@b{-[arm]v5t}|
287 [@b{-mthumb}|@b{-mall}]
288 [@b{-mfpa10}|@b{-mfpa11}|@b{-mfpe-old}|@b{-mno-fpu}]
290 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
291 @b{-mapcs-reentrant}]
292 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
296 @emph{Target D10V options:}
301 @emph{Target D30V options:}
302 [@b{-O}|@b{-n}|@b{-N}]
305 @c Hitachi family chips have no machine-dependent assembler options
308 @c HPPA has no machine-dependent assembler options (yet).
312 @emph{Target i386 options:}
317 @emph{Target i960 options:}
318 @c see md_parse_option in tc-i960.c
319 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
321 [@b{-b}] [@b{-no-relax}]
325 @emph{Target M32R options:}
326 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
331 @emph{Target M680X0 options:}
332 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
336 @emph{Target M68HC11 options:}
337 [@b{-m68hc11}|@b{-m68hc12}]
338 [@b{--force-long-branchs}] [@b{--short-branchs}]
339 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
340 [@b{--print-opcodes}] [@b{--generate-example}]
344 @emph{Target MCORE options:}
345 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
346 [@b{-mcpu=[210|340]}]
350 @emph{Target MIPS options:}
351 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
352 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
353 [@b{-mips32}] [@b{-mips64}]
354 [@b{-m4650}] [@b{-no-m4650}]
355 [@b{--trap}] [@b{--break}] [@b{-n}]
356 [@b{--emulation}=@var{name} ]
360 @emph{Target MMIX options:}
361 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
362 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
363 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
367 @emph{Target PDP11 options:}
368 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
369 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
370 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
374 @emph{Target picoJava options:}
379 @emph{Target PowerPC options:}
380 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
381 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
382 @b{-mbooke32}|@b{-mbooke64}]
383 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
384 [@b{-mregnames}|@b{-mno-regnames}]
385 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
386 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
387 [@b{-msolaris}|@b{-mno-solaris}]
391 @emph{Target SPARC options:}
392 @c The order here is important. See c-sparc.texi.
393 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
394 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
395 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
400 @emph{Target TIC54X options:}
401 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
402 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
405 @c Z8000 has no machine-dependent assembler options
414 Turn on listings, in any of a variety of ways:
418 omit false conditionals
421 omit debugging directives
424 include high-level source
430 include macro expansions
433 omit forms processing
439 set the name of the listing file
442 You may combine these options; for example, use @samp{-aln} for assembly
443 listing without forms processing. The @samp{=file} option, if used, must be
444 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
447 Ignored. This option is accepted for script compatibility with calls to
450 @item --defsym @var{sym}=@var{value}
451 Define the symbol @var{sym} to be @var{value} before assembling the input file.
452 @var{value} must be an integer constant. As in C, a leading @samp{0x}
453 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
456 ``fast''---skip whitespace and comment preprocessing (assume source is
460 Generate stabs debugging information for each assembler line. This
461 may help debugging assembler code, if the debugger can handle it.
464 Generate DWARF2 debugging information for each assembler line. This
465 may help debugging assembler code, if the debugger can handle it. Note - this
466 option is only supported by some targets, not all of them.
469 Print a summary of the command line options and exit.
472 Print a summary of all target specific options and exit.
475 Add directory @var{dir} to the search list for @code{.include} directives.
478 Don't warn about signed overflow.
481 @ifclear DIFF-TBL-KLUGE
482 This option is accepted but has no effect on the @value{TARGET} family.
484 @ifset DIFF-TBL-KLUGE
485 Issue warnings when difference tables altered for long displacements.
490 Keep (in the symbol table) local symbols. On traditional a.out systems
491 these start with @samp{L}, but different systems have different local
494 @item --listing-lhs-width=@var{number}
495 Set the maximum width, in words, of the output data column for an assembler
496 listing to @var{number}.
498 @item --listing-lhs-width2=@var{number}
499 Set the maximum width, in words, of the output data column for continuation
500 lines in an assembler listing to @var{number}.
502 @item --listing-rhs-width=@var{number}
503 Set the maximum width of an input source line, as displayed in a listing, to
506 @item --listing-cont-lines=@var{number}
507 Set the maximum number of lines printed in a listing for a single line of input
510 @item -o @var{objfile}
511 Name the object-file output from @command{@value{AS}} @var{objfile}.
514 Fold the data section into the text section.
517 Print the maximum space (in bytes) and total time (in seconds) used by
520 @item --strip-local-absolute
521 Remove local absolute symbols from the outgoing symbol table.
525 Print the @command{as} version.
528 Print the @command{as} version and exit.
532 Suppress warning messages.
534 @item --fatal-warnings
535 Treat warnings as errors.
538 Don't suppress warning messages or treat them as errors.
547 Generate an object file even after errors.
549 @item -- | @var{files} @dots{}
550 Standard input, or source files to assemble.
555 The following options are available when @value{AS} is configured for
560 This option selects the core processor variant.
562 Select either big-endian (-EB) or little-endian (-EL) output.
567 The following options are available when @value{AS} is configured for the ARM
571 @item -m[arm][1|2|3|6|7|8|9][...]
572 Specify which ARM processor variant is the target.
573 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
574 Specify which ARM architecture variant is used by the target.
575 @item -mthumb | -mall
576 Enable or disable Thumb only instruction decoding.
577 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
578 Select which Floating Point architecture is the target.
579 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
580 Select which procedure calling convention is in use.
582 Select either big-endian (-EB) or little-endian (-EL) output.
583 @item -mthumb-interwork
584 Specify that the code has been generated with interworking between Thumb and
587 Specify that PIC code has been generated.
592 The following options are available when @value{AS} is configured for
595 @cindex D10V optimization
596 @cindex optimization, D10V
598 Optimize output by parallelizing instructions.
603 The following options are available when @value{AS} is configured for a D30V
606 @cindex D30V optimization
607 @cindex optimization, D30V
609 Optimize output by parallelizing instructions.
613 Warn when nops are generated.
615 @cindex D30V nops after 32-bit multiply
617 Warn when a nop after a 32-bit multiply instruction is generated.
622 The following options are available when @value{AS} is configured for the
623 Intel 80960 processor.
626 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
627 Specify which variant of the 960 architecture is the target.
630 Add code to collect statistics about branches taken.
633 Do not alter compare-and-branch instructions for long displacements;
640 The following options are available when @value{AS} is configured for the
641 Mitsubishi M32R series.
646 Specify which processor in the M32R family is the target. The default
647 is normally the M32R, but this option changes it to the M32RX.
649 @item --warn-explicit-parallel-conflicts or --Wp
650 Produce warning messages when questionable parallel constructs are
653 @item --no-warn-explicit-parallel-conflicts or --Wnp
654 Do not produce warning messages when questionable parallel constructs are
661 The following options are available when @value{AS} is configured for the
662 Motorola 68000 series.
667 Shorten references to undefined symbols, to one word instead of two.
669 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
670 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
671 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
672 Specify what processor in the 68000 family is the target. The default
673 is normally the 68020, but this can be changed at configuration time.
675 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
676 The target machine does (or does not) have a floating-point coprocessor.
677 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
678 the basic 68000 is not compatible with the 68881, a combination of the
679 two can be specified, since it's possible to do emulation of the
680 coprocessor instructions with the main processor.
682 @item -m68851 | -mno-68851
683 The target machine does (or does not) have a memory-management
684 unit coprocessor. The default is to assume an MMU for 68020 and up.
691 For details about the PDP-11 machine dependent features options,
692 see @ref{PDP-11-Options}.
695 @item -mpic | -mno-pic
696 Generate position-independent (or position-dependent) code. The
697 default is @option{-mpic}.
700 @itemx -mall-extensions
701 Enable all instruction set extensions. This is the default.
703 @item -mno-extensions
704 Disable all instruction set extensions.
706 @item -m@var{extension} | -mno-@var{extension}
707 Enable (or disable) a particular instruction set extension.
710 Enable the instruction set extensions supported by a particular CPU, and
711 disable all other extensions.
713 @item -m@var{machine}
714 Enable the instruction set extensions supported by a particular machine
715 model, and disable all other extensions.
721 The following options are available when @value{AS} is configured for
722 a picoJava processor.
726 @cindex PJ endianness
727 @cindex endianness, PJ
728 @cindex big endian output, PJ
730 Generate ``big endian'' format output.
732 @cindex little endian output, PJ
734 Generate ``little endian'' format output.
740 The following options are available when @value{AS} is configured for the
741 Motorola 68HC11 or 68HC12 series.
745 @item -m68hc11 | -m68hc12
746 Specify what processor is the target. The default is
747 defined by the configuration option when building the assembler.
749 @item --force-long-branchs
750 Relative branches are turned into absolute ones. This concerns
751 conditional branches, unconditional branches and branches to a
754 @item -S | --short-branchs
755 Do not turn relative branchs into absolute ones
756 when the offset is out of range.
758 @item --strict-direct-mode
759 Do not turn the direct addressing mode into extended addressing mode
760 when the instruction does not support direct addressing mode.
762 @item --print-insn-syntax
763 Print the syntax of instruction in case of error.
765 @item --print-opcodes
766 print the list of instructions with syntax and then exit.
768 @item --generate-example
769 print an example of instruction for each possible instruction and then exit.
770 This option is only useful for testing @command{@value{AS}}.
776 The following options are available when @command{@value{AS}} is configured
777 for the SPARC architecture:
780 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
781 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
782 Explicitly select a variant of the SPARC architecture.
784 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
785 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
787 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
788 UltraSPARC extensions.
790 @item -xarch=v8plus | -xarch=v8plusa
791 For compatibility with the Solaris v9 assembler. These options are
792 equivalent to -Av8plus and -Av8plusa, respectively.
795 Warn when the assembler switches to another architecture.
800 The following options are available when @value{AS} is configured for the 'c54x
805 Enable extended addressing mode. All addresses and relocations will assume
806 extended addressing (usually 23 bits).
807 @item -mcpu=@var{CPU_VERSION}
808 Sets the CPU version being compiled for.
809 @item -merrors-to-file @var{FILENAME}
810 Redirect error output to a file, for broken systems which don't support such
811 behaviour in the shell.
816 The following options are available when @value{AS} is configured for
821 This option sets the largest size of an object that can be referenced
822 implicitly with the @code{gp} register. It is only accepted for targets that
823 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
825 @cindex MIPS endianness
826 @cindex endianness, MIPS
827 @cindex big endian output, MIPS
829 Generate ``big endian'' format output.
831 @cindex little endian output, MIPS
833 Generate ``little endian'' format output.
842 Generate code for a particular MIPS Instruction Set Architecture level.
843 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
844 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
846 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
847 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
848 processors, respectively.
852 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
853 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
854 instructions around accesses to the @samp{HI} and @samp{LO} registers.
855 @samp{-no-m4650} turns off this option.
857 @item -mcpu=@var{CPU}
858 Generate code for a particular MIPS cpu. It is exactly equivalent to
859 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
863 @item --emulation=@var{name}
864 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
865 for some other target, in all respects, including output format (choosing
866 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
867 debugging information or store symbol table information, and default
868 endianness. The available configuration names are: @samp{mipsecoff},
869 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
870 @samp{mipsbelf}. The first two do not alter the default endianness from that
871 of the primary target for which the assembler was configured; the others change
872 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
873 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
874 selection in any case.
876 This option is currently supported only when the primary target
877 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
878 Furthermore, the primary target or others specified with
879 @samp{--enable-targets=@dots{}} at configuration time must include support for
880 the other format, if both are to be available. For example, the Irix 5
881 configuration includes support for both.
883 Eventually, this option will support more configurations, with more
884 fine-grained control over the assembler's behavior, and will be supported for
888 @command{@value{AS}} ignores this option. It is accepted for compatibility with
896 Control how to deal with multiplication overflow and division by zero.
897 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
898 (and only work for Instruction Set Architecture level 2 and higher);
899 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
903 When this option is used, @command{@value{AS}} will issue a warning every
904 time it generates a nop instruction from a macro.
909 The following options are available when @value{AS} is configured for
915 Enable or disable the JSRI to BSR transformation. By default this is enabled.
916 The command line option @samp{-nojsri2bsr} can be used to disable it.
920 Enable or disable the silicon filter behaviour. By default this is disabled.
921 The default can be overridden by the @samp{-sifilter} command line option.
924 Alter jump instructions for long displacements.
926 @item -mcpu=[210|340]
927 Select the cpu type on the target hardware. This controls which instructions
931 Assemble for a big endian target.
934 Assemble for a little endian target.
940 See the info pages for documentation of the MMIX-specific options.
946 * Manual:: Structure of this Manual
947 * GNU Assembler:: The GNU Assembler
948 * Object Formats:: Object File Formats
949 * Command Line:: Command Line
950 * Input Files:: Input Files
951 * Object:: Output (Object) File
952 * Errors:: Error and Warning Messages
956 @section Structure of this Manual
958 @cindex manual, structure and purpose
959 This manual is intended to describe what you need to know to use
960 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
961 notation for symbols, constants, and expressions; the directives that
962 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
965 We also cover special features in the @value{TARGET}
966 configuration of @command{@value{AS}}, including assembler directives.
969 This manual also describes some of the machine-dependent features of
970 various flavors of the assembler.
973 @cindex machine instructions (not covered)
974 On the other hand, this manual is @emph{not} intended as an introduction
975 to programming in assembly language---let alone programming in general!
976 In a similar vein, we make no attempt to introduce the machine
977 architecture; we do @emph{not} describe the instruction set, standard
978 mnemonics, registers or addressing modes that are standard to a
979 particular architecture.
981 You may want to consult the manufacturer's
982 machine architecture manual for this information.
986 For information on the H8/300 machine instruction set, see @cite{H8/300
987 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
988 see @cite{H8/300H Series Programming Manual} (Hitachi).
991 For information on the H8/500 machine instruction set, see @cite{H8/500
992 Series Programming Manual} (Hitachi M21T001).
995 For information on the Hitachi SH machine instruction set, see
996 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
999 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1003 @c I think this is premature---doc@cygnus.com, 17jan1991
1005 Throughout this manual, we assume that you are running @dfn{GNU},
1006 the portable operating system from the @dfn{Free Software
1007 Foundation, Inc.}. This restricts our attention to certain kinds of
1008 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1009 once this assumption is granted examples and definitions need less
1012 @command{@value{AS}} is part of a team of programs that turn a high-level
1013 human-readable series of instructions into a low-level
1014 computer-readable series of instructions. Different versions of
1015 @command{@value{AS}} are used for different kinds of computer.
1018 @c There used to be a section "Terminology" here, which defined
1019 @c "contents", "byte", "word", and "long". Defining "word" to any
1020 @c particular size is confusing when the .word directive may generate 16
1021 @c bits on one machine and 32 bits on another; in general, for the user
1022 @c version of this manual, none of these terms seem essential to define.
1023 @c They were used very little even in the former draft of the manual;
1024 @c this draft makes an effort to avoid them (except in names of
1028 @section The GNU Assembler
1030 @c man begin DESCRIPTION
1032 @sc{gnu} @command{as} is really a family of assemblers.
1034 This manual describes @command{@value{AS}}, a member of that family which is
1035 configured for the @value{TARGET} architectures.
1037 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1038 should find a fairly similar environment when you use it on another
1039 architecture. Each version has much in common with the others,
1040 including object file formats, most assembler directives (often called
1041 @dfn{pseudo-ops}) and assembler syntax.@refill
1043 @cindex purpose of @sc{gnu} assembler
1044 @command{@value{AS}} is primarily intended to assemble the output of the
1045 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1046 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1047 assemble correctly everything that other assemblers for the same
1048 machine would assemble.
1050 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1053 @c This remark should appear in generic version of manual; assumption
1054 @c here is that generic version sets M680x0.
1055 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1056 assembler for the same architecture; for example, we know of several
1057 incompatible versions of 680x0 assembly language syntax.
1062 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1063 program in one pass of the source file. This has a subtle impact on the
1064 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1066 @node Object Formats
1067 @section Object File Formats
1069 @cindex object file format
1070 The @sc{gnu} assembler can be configured to produce several alternative
1071 object file formats. For the most part, this does not affect how you
1072 write assembly language programs; but directives for debugging symbols
1073 are typically different in different file formats. @xref{Symbol
1074 Attributes,,Symbol Attributes}.
1077 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1078 @value{OBJ-NAME} format object files.
1080 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1082 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1083 @code{a.out} or COFF format object files.
1086 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1087 @code{b.out} or COFF format object files.
1090 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1091 SOM or ELF format object files.
1096 @section Command Line
1098 @cindex command line conventions
1100 After the program name @command{@value{AS}}, the command line may contain
1101 options and file names. Options may appear in any order, and may be
1102 before, after, or between file names. The order of file names is
1105 @cindex standard input, as input file
1107 @file{--} (two hyphens) by itself names the standard input file
1108 explicitly, as one of the files for @command{@value{AS}} to assemble.
1110 @cindex options, command line
1111 Except for @samp{--} any command line argument that begins with a
1112 hyphen (@samp{-}) is an option. Each option changes the behavior of
1113 @command{@value{AS}}. No option changes the way another option works. An
1114 option is a @samp{-} followed by one or more letters; the case of
1115 the letter is important. All options are optional.
1117 Some options expect exactly one file name to follow them. The file
1118 name may either immediately follow the option's letter (compatible
1119 with older assemblers) or it may be the next command argument (@sc{gnu}
1120 standard). These two command lines are equivalent:
1123 @value{AS} -o my-object-file.o mumble.s
1124 @value{AS} -omy-object-file.o mumble.s
1128 @section Input Files
1131 @cindex source program
1132 @cindex files, input
1133 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1134 describe the program input to one run of @command{@value{AS}}. The program may
1135 be in one or more files; how the source is partitioned into files
1136 doesn't change the meaning of the source.
1138 @c I added "con" prefix to "catenation" just to prove I can overcome my
1139 @c APL training... doc@cygnus.com
1140 The source program is a concatenation of the text in all the files, in the
1143 @c man begin DESCRIPTION
1144 Each time you run @command{@value{AS}} it assembles exactly one source
1145 program. The source program is made up of one or more files.
1146 (The standard input is also a file.)
1148 You give @command{@value{AS}} a command line that has zero or more input file
1149 names. The input files are read (from left file name to right). A
1150 command line argument (in any position) that has no special meaning
1151 is taken to be an input file name.
1153 If you give @command{@value{AS}} no file names it attempts to read one input file
1154 from the @command{@value{AS}} standard input, which is normally your terminal. You
1155 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1158 Use @samp{--} if you need to explicitly name the standard input file
1159 in your command line.
1161 If the source is empty, @command{@value{AS}} produces a small, empty object
1166 @subheading Filenames and Line-numbers
1168 @cindex input file linenumbers
1169 @cindex line numbers, in input files
1170 There are two ways of locating a line in the input file (or files) and
1171 either may be used in reporting error messages. One way refers to a line
1172 number in a physical file; the other refers to a line number in a
1173 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1175 @dfn{Physical files} are those files named in the command line given
1176 to @command{@value{AS}}.
1178 @dfn{Logical files} are simply names declared explicitly by assembler
1179 directives; they bear no relation to physical files. Logical file names help
1180 error messages reflect the original source file, when @command{@value{AS}} source
1181 is itself synthesized from other files. @command{@value{AS}} understands the
1182 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1183 @ref{File,,@code{.file}}.
1186 @section Output (Object) File
1192 Every time you run @command{@value{AS}} it produces an output file, which is
1193 your assembly language program translated into numbers. This file
1194 is the object file. Its default name is
1202 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1204 You can give it another name by using the @option{-o} option. Conventionally,
1205 object file names end with @file{.o}. The default name is used for historical
1206 reasons: older assemblers were capable of assembling self-contained programs
1207 directly into a runnable program. (For some formats, this isn't currently
1208 possible, but it can be done for the @code{a.out} format.)
1212 The object file is meant for input to the linker @code{@value{LD}}. It contains
1213 assembled program code, information to help @code{@value{LD}} integrate
1214 the assembled program into a runnable file, and (optionally) symbolic
1215 information for the debugger.
1217 @c link above to some info file(s) like the description of a.out.
1218 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1221 @section Error and Warning Messages
1223 @c man begin DESCRIPTION
1225 @cindex error messages
1226 @cindex warning messages
1227 @cindex messages from assembler
1228 @command{@value{AS}} may write warnings and error messages to the standard error
1229 file (usually your terminal). This should not happen when a compiler
1230 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1231 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1232 grave problem that stops the assembly.
1236 @cindex format of warning messages
1237 Warning messages have the format
1240 file_name:@b{NNN}:Warning Message Text
1244 @cindex line numbers, in warnings/errors
1245 (where @b{NNN} is a line number). If a logical file name has been given
1246 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1247 the current input file is used. If a logical line number was given
1249 (@pxref{Line,,@code{.line}})
1253 (@pxref{Line,,@code{.line}})
1256 (@pxref{Ln,,@code{.ln}})
1259 then it is used to calculate the number printed,
1260 otherwise the actual line in the current source file is printed. The
1261 message text is intended to be self explanatory (in the grand Unix
1264 @cindex format of error messages
1265 Error messages have the format
1267 file_name:@b{NNN}:FATAL:Error Message Text
1269 The file name and line number are derived as for warning
1270 messages. The actual message text may be rather less explanatory
1271 because many of them aren't supposed to happen.
1274 @chapter Command-Line Options
1276 @cindex options, all versions of assembler
1277 This chapter describes command-line options available in @emph{all}
1278 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1280 to the @value{TARGET}.
1283 to particular machine architectures.
1286 @c man begin DESCRIPTION
1288 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1289 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1290 The assembler arguments must be separated from each other (and the @samp{-Wa})
1291 by commas. For example:
1294 gcc -c -g -O -Wa,-alh,-L file.c
1298 This passes two options to the assembler: @samp{-alh} (emit a listing to
1299 standard output with with high-level and assembly source) and @samp{-L} (retain
1300 local symbols in the symbol table).
1302 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1303 command-line options are automatically passed to the assembler by the compiler.
1304 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1305 precisely what options it passes to each compilation pass, including the
1311 * a:: -a[cdhlns] enable listings
1312 * D:: -D for compatibility
1313 * f:: -f to work faster
1314 * I:: -I for .include search path
1315 @ifclear DIFF-TBL-KLUGE
1316 * K:: -K for compatibility
1318 @ifset DIFF-TBL-KLUGE
1319 * K:: -K for difference tables
1322 * L:: -L to retain local labels
1323 * listing:: --listing-XXX to configure listing output
1324 * M:: -M or --mri to assemble in MRI compatibility mode
1325 * MD:: --MD for dependency tracking
1326 * o:: -o to name the object file
1327 * R:: -R to join data and text sections
1328 * statistics:: --statistics to see statistics about assembly
1329 * traditional-format:: --traditional-format for compatible output
1330 * v:: -v to announce version
1331 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1332 * Z:: -Z to make object file even after errors
1336 @section Enable Listings: @option{-a[cdhlns]}
1345 @cindex listings, enabling
1346 @cindex assembly listings, enabling
1348 These options enable listing output from the assembler. By itself,
1349 @samp{-a} requests high-level, assembly, and symbols listing.
1350 You can use other letters to select specific options for the list:
1351 @samp{-ah} requests a high-level language listing,
1352 @samp{-al} requests an output-program assembly listing, and
1353 @samp{-as} requests a symbol table listing.
1354 High-level listings require that a compiler debugging option like
1355 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1358 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1359 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1360 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1361 omitted from the listing.
1363 Use the @samp{-ad} option to omit debugging directives from the
1366 Once you have specified one of these options, you can further control
1367 listing output and its appearance using the directives @code{.list},
1368 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1370 The @samp{-an} option turns off all forms processing.
1371 If you do not request listing output with one of the @samp{-a} options, the
1372 listing-control directives have no effect.
1374 The letters after @samp{-a} may be combined into one option,
1375 @emph{e.g.}, @samp{-aln}.
1377 Note if the assembler source is coming from the standard input (eg because it
1378 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1379 is being used) then the listing will not contain any comments or preprocessor
1380 directives. This is because the listing code buffers input source lines from
1381 stdin only after they have been preprocessed by the assembler. This reduces
1382 memory usage and makes the code more efficient.
1385 @section @option{-D}
1388 This option has no effect whatsoever, but it is accepted to make it more
1389 likely that scripts written for other assemblers also work with
1390 @command{@value{AS}}.
1393 @section Work Faster: @option{-f}
1396 @cindex trusted compiler
1397 @cindex faster processing (@option{-f})
1398 @samp{-f} should only be used when assembling programs written by a
1399 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1400 and comment preprocessing on
1401 the input file(s) before assembling them. @xref{Preprocessing,
1405 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1406 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1411 @section @code{.include} search path: @option{-I} @var{path}
1413 @kindex -I @var{path}
1414 @cindex paths for @code{.include}
1415 @cindex search path for @code{.include}
1416 @cindex @code{include} directive search path
1417 Use this option to add a @var{path} to the list of directories
1418 @command{@value{AS}} searches for files specified in @code{.include}
1419 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1420 many times as necessary to include a variety of paths. The current
1421 working directory is always searched first; after that, @command{@value{AS}}
1422 searches any @samp{-I} directories in the same order as they were
1423 specified (left to right) on the command line.
1426 @section Difference Tables: @option{-K}
1429 @ifclear DIFF-TBL-KLUGE
1430 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1431 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1432 where it can be used to warn when the assembler alters the machine code
1433 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1434 family does not have the addressing limitations that sometimes lead to this
1435 alteration on other platforms.
1438 @ifset DIFF-TBL-KLUGE
1439 @cindex difference tables, warning
1440 @cindex warning for altered difference tables
1441 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1442 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1443 You can use the @samp{-K} option if you want a warning issued when this
1448 @section Include Local Labels: @option{-L}
1451 @cindex local labels, retaining in output
1452 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1453 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1454 debugging, because they are intended for the use of programs (like
1455 compilers) that compose assembler programs, not for your notice.
1456 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1457 normally debug with them.
1459 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1460 in the object file. Usually if you do this you also tell the linker
1461 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1463 By default, a local label is any label beginning with @samp{L}, but each
1464 target is allowed to redefine the local label prefix.
1466 On the HPPA local labels begin with @samp{L$}.
1470 @section Configuring listing output: @option{--listing}
1472 The listing feature of the assembler can be enabled via the command line switch
1473 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1474 hex dump of the corresponding locations in the output object file, and displays
1475 them as a listing file. The format of this listing can be controlled by pseudo
1476 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1477 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1480 @item --listing-lhs-width=@samp{number}
1481 @kindex --listing-lhs-width
1482 @cindex Width of first line disassembly output
1483 Sets the maximum width, in words, of the first line of the hex byte dump. This
1484 dump appears on the left hand side of the listing output.
1486 @item --listing-lhs-width2=@samp{number}
1487 @kindex --listing-lhs-width2
1488 @cindex Width of continuation lines of disassembly output
1489 Sets the maximum width, in words, of any further lines of the hex byte dump for
1490 a given inut source line. If this value is not specified, it defaults to being
1491 the same as the value specified for @samp{--listing-lhs-width}. If neither
1492 switch is used the default is to one.
1494 @item --listing-rhs-width=@samp{number}
1495 @kindex --listing-rhs-width
1496 @cindex Width of source line output
1497 Sets the maximum width, in characters, of the source line that is displayed
1498 alongside the hex dump. The default value for this parameter is 100. The
1499 source line is displayed on the right hand side of the listing output.
1501 @item --listing-cont-lines=@samp{number}
1502 @kindex --listing-cont-lines
1503 @cindex Maximum number of continuation lines
1504 Sets the maximum number of continuation lines of hex dump that will be
1505 displayed for a given single line of source input. The default value is 4.
1509 @section Assemble in MRI Compatibility Mode: @option{-M}
1512 @cindex MRI compatibility mode
1513 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1514 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1515 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1516 configured target) assembler from Microtec Research. The exact nature of the
1517 MRI syntax will not be documented here; see the MRI manuals for more
1518 information. Note in particular that the handling of macros and macro
1519 arguments is somewhat different. The purpose of this option is to permit
1520 assembling existing MRI assembler code using @command{@value{AS}}.
1522 The MRI compatibility is not complete. Certain operations of the MRI assembler
1523 depend upon its object file format, and can not be supported using other object
1524 file formats. Supporting these would require enhancing each object file format
1525 individually. These are:
1528 @item global symbols in common section
1530 The m68k MRI assembler supports common sections which are merged by the linker.
1531 Other object file formats do not support this. @command{@value{AS}} handles
1532 common sections by treating them as a single common symbol. It permits local
1533 symbols to be defined within a common section, but it can not support global
1534 symbols, since it has no way to describe them.
1536 @item complex relocations
1538 The MRI assemblers support relocations against a negated section address, and
1539 relocations which combine the start addresses of two or more sections. These
1540 are not support by other object file formats.
1542 @item @code{END} pseudo-op specifying start address
1544 The MRI @code{END} pseudo-op permits the specification of a start address.
1545 This is not supported by other object file formats. The start address may
1546 instead be specified using the @option{-e} option to the linker, or in a linker
1549 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1551 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1552 name to the output file. This is not supported by other object file formats.
1554 @item @code{ORG} pseudo-op
1556 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1557 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1558 which changes the location within the current section. Absolute sections are
1559 not supported by other object file formats. The address of a section may be
1560 assigned within a linker script.
1563 There are some other features of the MRI assembler which are not supported by
1564 @command{@value{AS}}, typically either because they are difficult or because they
1565 seem of little consequence. Some of these may be supported in future releases.
1569 @item EBCDIC strings
1571 EBCDIC strings are not supported.
1573 @item packed binary coded decimal
1575 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1576 and @code{DCB.P} pseudo-ops are not supported.
1578 @item @code{FEQU} pseudo-op
1580 The m68k @code{FEQU} pseudo-op is not supported.
1582 @item @code{NOOBJ} pseudo-op
1584 The m68k @code{NOOBJ} pseudo-op is not supported.
1586 @item @code{OPT} branch control options
1588 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1589 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1590 relaxes all branches, whether forward or backward, to an appropriate size, so
1591 these options serve no purpose.
1593 @item @code{OPT} list control options
1595 The following m68k @code{OPT} list control options are ignored: @code{C},
1596 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1597 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1599 @item other @code{OPT} options
1601 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1602 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1604 @item @code{OPT} @code{D} option is default
1606 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1607 @code{OPT NOD} may be used to turn it off.
1609 @item @code{XREF} pseudo-op.
1611 The m68k @code{XREF} pseudo-op is ignored.
1613 @item @code{.debug} pseudo-op
1615 The i960 @code{.debug} pseudo-op is not supported.
1617 @item @code{.extended} pseudo-op
1619 The i960 @code{.extended} pseudo-op is not supported.
1621 @item @code{.list} pseudo-op.
1623 The various options of the i960 @code{.list} pseudo-op are not supported.
1625 @item @code{.optimize} pseudo-op
1627 The i960 @code{.optimize} pseudo-op is not supported.
1629 @item @code{.output} pseudo-op
1631 The i960 @code{.output} pseudo-op is not supported.
1633 @item @code{.setreal} pseudo-op
1635 The i960 @code{.setreal} pseudo-op is not supported.
1640 @section Dependency tracking: @option{--MD}
1643 @cindex dependency tracking
1646 @command{@value{AS}} can generate a dependency file for the file it creates. This
1647 file consists of a single rule suitable for @code{make} describing the
1648 dependencies of the main source file.
1650 The rule is written to the file named in its argument.
1652 This feature is used in the automatic updating of makefiles.
1655 @section Name the Object File: @option{-o}
1658 @cindex naming object file
1659 @cindex object file name
1660 There is always one object file output when you run @command{@value{AS}}. By
1661 default it has the name
1664 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1678 You use this option (which takes exactly one filename) to give the
1679 object file a different name.
1681 Whatever the object file is called, @command{@value{AS}} overwrites any
1682 existing file of the same name.
1685 @section Join Data and Text Sections: @option{-R}
1688 @cindex data and text sections, joining
1689 @cindex text and data sections, joining
1690 @cindex joining text and data sections
1691 @cindex merging text and data sections
1692 @option{-R} tells @command{@value{AS}} to write the object file as if all
1693 data-section data lives in the text section. This is only done at
1694 the very last moment: your binary data are the same, but data
1695 section parts are relocated differently. The data section part of
1696 your object file is zero bytes long because all its bytes are
1697 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1699 When you specify @option{-R} it would be possible to generate shorter
1700 address displacements (because we do not have to cross between text and
1701 data section). We refrain from doing this simply for compatibility with
1702 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1705 When @command{@value{AS}} is configured for COFF output,
1706 this option is only useful if you use sections named @samp{.text} and
1711 @option{-R} is not supported for any of the HPPA targets. Using
1712 @option{-R} generates a warning from @command{@value{AS}}.
1716 @section Display Assembly Statistics: @option{--statistics}
1718 @kindex --statistics
1719 @cindex statistics, about assembly
1720 @cindex time, total for assembly
1721 @cindex space used, maximum for assembly
1722 Use @samp{--statistics} to display two statistics about the resources used by
1723 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1724 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1727 @node traditional-format
1728 @section Compatible output: @option{--traditional-format}
1730 @kindex --traditional-format
1731 For some targets, the output of @command{@value{AS}} is different in some ways
1732 from the output of some existing assembler. This switch requests
1733 @command{@value{AS}} to use the traditional format instead.
1735 For example, it disables the exception frame optimizations which
1736 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1739 @section Announce Version: @option{-v}
1743 @cindex assembler version
1744 @cindex version of assembler
1745 You can find out what version of as is running by including the
1746 option @samp{-v} (which you can also spell as @samp{-version}) on the
1750 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1752 @command{@value{AS}} should never give a warning or error message when
1753 assembling compiler output. But programs written by people often
1754 cause @command{@value{AS}} to give a warning that a particular assumption was
1755 made. All such warnings are directed to the standard error file.
1758 @kindex @samp{--no-warn}
1759 @cindex suppressing warnings
1760 @cindex warnings, suppressing
1761 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1762 This only affects the warning messages: it does not change any particular of
1763 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1766 @kindex @samp{--fatal-warnings}
1767 @cindex errors, caused by warnings
1768 @cindex warnings, causing error
1769 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1770 files that generate warnings to be in error.
1772 @kindex @samp{--warn}
1773 @cindex warnings, switching on
1774 You can switch these options off again by specifying @option{--warn}, which
1775 causes warnings to be output as usual.
1778 @section Generate Object File in Spite of Errors: @option{-Z}
1779 @cindex object file, after errors
1780 @cindex errors, continuing after
1781 After an error message, @command{@value{AS}} normally produces no output. If for
1782 some reason you are interested in object file output even after
1783 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1784 option. If there are any errors, @command{@value{AS}} continues anyways, and
1785 writes an object file after a final warning message of the form @samp{@var{n}
1786 errors, @var{m} warnings, generating bad object file.}
1791 @cindex machine-independent syntax
1792 @cindex syntax, machine-independent
1793 This chapter describes the machine-independent syntax allowed in a
1794 source file. @command{@value{AS}} syntax is similar to what many other
1795 assemblers use; it is inspired by the BSD 4.2
1800 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1804 * Preprocessing:: Preprocessing
1805 * Whitespace:: Whitespace
1806 * Comments:: Comments
1807 * Symbol Intro:: Symbols
1808 * Statements:: Statements
1809 * Constants:: Constants
1813 @section Preprocessing
1815 @cindex preprocessing
1816 The @command{@value{AS}} internal preprocessor:
1818 @cindex whitespace, removed by preprocessor
1820 adjusts and removes extra whitespace. It leaves one space or tab before
1821 the keywords on a line, and turns any other whitespace on the line into
1824 @cindex comments, removed by preprocessor
1826 removes all comments, replacing them with a single space, or an
1827 appropriate number of newlines.
1829 @cindex constants, converted by preprocessor
1831 converts character constants into the appropriate numeric values.
1834 It does not do macro processing, include file handling, or
1835 anything else you may get from your C compiler's preprocessor. You can
1836 do include file processing with the @code{.include} directive
1837 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1838 to get other ``CPP'' style preprocessing, by giving the input file a
1839 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1840 Output, gcc.info, Using GNU CC}.
1842 Excess whitespace, comments, and character constants
1843 cannot be used in the portions of the input text that are not
1846 @cindex turning preprocessing on and off
1847 @cindex preprocessing, turning on and off
1850 If the first line of an input file is @code{#NO_APP} or if you use the
1851 @samp{-f} option, whitespace and comments are not removed from the input file.
1852 Within an input file, you can ask for whitespace and comment removal in
1853 specific portions of the by putting a line that says @code{#APP} before the
1854 text that may contain whitespace or comments, and putting a line that says
1855 @code{#NO_APP} after this text. This feature is mainly intend to support
1856 @code{asm} statements in compilers whose output is otherwise free of comments
1863 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1864 Whitespace is used to separate symbols, and to make programs neater for
1865 people to read. Unless within character constants
1866 (@pxref{Characters,,Character Constants}), any whitespace means the same
1867 as exactly one space.
1873 There are two ways of rendering comments to @command{@value{AS}}. In both
1874 cases the comment is equivalent to one space.
1876 Anything from @samp{/*} through the next @samp{*/} is a comment.
1877 This means you may not nest these comments.
1881 The only way to include a newline ('\n') in a comment
1882 is to use this sort of comment.
1885 /* This sort of comment does not nest. */
1888 @cindex line comment character
1889 Anything from the @dfn{line comment} character to the next newline
1890 is considered a comment and is ignored. The line comment character is
1892 @samp{;} for the AMD 29K family;
1895 @samp{;} on the ARC;
1898 @samp{@@} on the ARM;
1901 @samp{;} for the H8/300 family;
1904 @samp{!} for the H8/500 family;
1907 @samp{;} for the HPPA;
1910 @samp{#} on the i386 and x86-64;
1913 @samp{#} on the i960;
1916 @samp{;} for the PDP-11;
1919 @samp{;} for picoJava;
1922 @samp{;} for Motorola PowerPC;
1925 @samp{!} for the Hitachi SH;
1928 @samp{!} on the SPARC;
1931 @samp{#} on the m32r;
1934 @samp{|} on the 680x0;
1937 @samp{#} on the 68HC11 and 68HC12;
1940 @samp{;} on the M880x0;
1943 @samp{#} on the Vax;
1946 @samp{!} for the Z8000;
1949 @samp{#} on the V850;
1951 see @ref{Machine Dependencies}. @refill
1952 @c FIXME What about i860?
1955 On some machines there are two different line comment characters. One
1956 character only begins a comment if it is the first non-whitespace character on
1957 a line, while the other always begins a comment.
1961 The V850 assembler also supports a double dash as starting a comment that
1962 extends to the end of the line.
1968 @cindex lines starting with @code{#}
1969 @cindex logical line numbers
1970 To be compatible with past assemblers, lines that begin with @samp{#} have a
1971 special interpretation. Following the @samp{#} should be an absolute
1972 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1973 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1974 new logical file name. The rest of the line, if any, should be whitespace.
1976 If the first non-whitespace characters on the line are not numeric,
1977 the line is ignored. (Just like a comment.)
1980 # This is an ordinary comment.
1981 # 42-6 "new_file_name" # New logical file name
1982 # This is logical line # 36.
1984 This feature is deprecated, and may disappear from future versions
1985 of @command{@value{AS}}.
1990 @cindex characters used in symbols
1991 @ifclear SPECIAL-SYMS
1992 A @dfn{symbol} is one or more characters chosen from the set of all
1993 letters (both upper and lower case), digits and the three characters
1999 A @dfn{symbol} is one or more characters chosen from the set of all
2000 letters (both upper and lower case), digits and the three characters
2001 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2007 On most machines, you can also use @code{$} in symbol names; exceptions
2008 are noted in @ref{Machine Dependencies}.
2010 No symbol may begin with a digit. Case is significant.
2011 There is no length limit: all characters are significant. Symbols are
2012 delimited by characters not in that set, or by the beginning of a file
2013 (since the source program must end with a newline, the end of a file is
2014 not a possible symbol delimiter). @xref{Symbols}.
2015 @cindex length of symbols
2020 @cindex statements, structure of
2021 @cindex line separator character
2022 @cindex statement separator character
2024 @ifclear abnormal-separator
2025 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2026 semicolon (@samp{;}). The newline or semicolon is considered part of
2027 the preceding statement. Newlines and semicolons within character
2028 constants are an exception: they do not end statements.
2030 @ifset abnormal-separator
2032 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2033 sign (@samp{@@}). The newline or at sign is considered part of the
2034 preceding statement. Newlines and at signs within character constants
2035 are an exception: they do not end statements.
2038 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2039 point (@samp{!}). The newline or exclamation point is considered part of the
2040 preceding statement. Newlines and exclamation points within character
2041 constants are an exception: they do not end statements.
2044 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2045 H8/300) a dollar sign (@samp{$}); or (for the
2048 (@samp{;}). The newline or separator character is considered part of
2049 the preceding statement. Newlines and separators within character
2050 constants are an exception: they do not end statements.
2055 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2056 separator character. (The line separator is usually @samp{;}, unless
2057 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2058 newline or separator character is considered part of the preceding
2059 statement. Newlines and separators within character constants are an
2060 exception: they do not end statements.
2063 @cindex newline, required at file end
2064 @cindex EOF, newline must precede
2065 It is an error to end any statement with end-of-file: the last
2066 character of any input file should be a newline.@refill
2068 An empty statement is allowed, and may include whitespace. It is ignored.
2070 @cindex instructions and directives
2071 @cindex directives and instructions
2072 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2073 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2075 A statement begins with zero or more labels, optionally followed by a
2076 key symbol which determines what kind of statement it is. The key
2077 symbol determines the syntax of the rest of the statement. If the
2078 symbol begins with a dot @samp{.} then the statement is an assembler
2079 directive: typically valid for any computer. If the symbol begins with
2080 a letter the statement is an assembly language @dfn{instruction}: it
2081 assembles into a machine language instruction.
2083 Different versions of @command{@value{AS}} for different computers
2084 recognize different instructions. In fact, the same symbol may
2085 represent a different instruction in a different computer's assembly
2089 @cindex @code{:} (label)
2090 @cindex label (@code{:})
2091 A label is a symbol immediately followed by a colon (@code{:}).
2092 Whitespace before a label or after a colon is permitted, but you may not
2093 have whitespace between a label's symbol and its colon. @xref{Labels}.
2096 For HPPA targets, labels need not be immediately followed by a colon, but
2097 the definition of a label must begin in column zero. This also implies that
2098 only one label may be defined on each line.
2102 label: .directive followed by something
2103 another_label: # This is an empty statement.
2104 instruction operand_1, operand_2, @dots{}
2111 A constant is a number, written so that its value is known by
2112 inspection, without knowing any context. Like this:
2115 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2116 .ascii "Ring the bell\7" # A string constant.
2117 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2118 .float 0f-314159265358979323846264338327\
2119 95028841971.693993751E-40 # - pi, a flonum.
2124 * Characters:: Character Constants
2125 * Numbers:: Number Constants
2129 @subsection Character Constants
2131 @cindex character constants
2132 @cindex constants, character
2133 There are two kinds of character constants. A @dfn{character} stands
2134 for one character in one byte and its value may be used in
2135 numeric expressions. String constants (properly called string
2136 @emph{literals}) are potentially many bytes and their values may not be
2137 used in arithmetic expressions.
2141 * Chars:: Characters
2145 @subsubsection Strings
2147 @cindex string constants
2148 @cindex constants, string
2149 A @dfn{string} is written between double-quotes. It may contain
2150 double-quotes or null characters. The way to get special characters
2151 into a string is to @dfn{escape} these characters: precede them with
2152 a backslash @samp{\} character. For example @samp{\\} represents
2153 one backslash: the first @code{\} is an escape which tells
2154 @command{@value{AS}} to interpret the second character literally as a backslash
2155 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2156 escape character). The complete list of escapes follows.
2158 @cindex escape codes, character
2159 @cindex character escape codes
2162 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2164 @cindex @code{\b} (backspace character)
2165 @cindex backspace (@code{\b})
2167 Mnemonic for backspace; for ASCII this is octal code 010.
2170 @c Mnemonic for EOText; for ASCII this is octal code 004.
2172 @cindex @code{\f} (formfeed character)
2173 @cindex formfeed (@code{\f})
2175 Mnemonic for FormFeed; for ASCII this is octal code 014.
2177 @cindex @code{\n} (newline character)
2178 @cindex newline (@code{\n})
2180 Mnemonic for newline; for ASCII this is octal code 012.
2183 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2185 @cindex @code{\r} (carriage return character)
2186 @cindex carriage return (@code{\r})
2188 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2191 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2192 @c other assemblers.
2194 @cindex @code{\t} (tab)
2195 @cindex tab (@code{\t})
2197 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2200 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2201 @c @item \x @var{digit} @var{digit} @var{digit}
2202 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2204 @cindex @code{\@var{ddd}} (octal character code)
2205 @cindex octal character code (@code{\@var{ddd}})
2206 @item \ @var{digit} @var{digit} @var{digit}
2207 An octal character code. The numeric code is 3 octal digits.
2208 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2209 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2211 @cindex @code{\@var{xd...}} (hex character code)
2212 @cindex hex character code (@code{\@var{xd...}})
2213 @item \@code{x} @var{hex-digits...}
2214 A hex character code. All trailing hex digits are combined. Either upper or
2215 lower case @code{x} works.
2217 @cindex @code{\\} (@samp{\} character)
2218 @cindex backslash (@code{\\})
2220 Represents one @samp{\} character.
2223 @c Represents one @samp{'} (accent acute) character.
2224 @c This is needed in single character literals
2225 @c (@xref{Characters,,Character Constants}.) to represent
2228 @cindex @code{\"} (doublequote character)
2229 @cindex doublequote (@code{\"})
2231 Represents one @samp{"} character. Needed in strings to represent
2232 this character, because an unescaped @samp{"} would end the string.
2234 @item \ @var{anything-else}
2235 Any other character when escaped by @kbd{\} gives a warning, but
2236 assembles as if the @samp{\} was not present. The idea is that if
2237 you used an escape sequence you clearly didn't want the literal
2238 interpretation of the following character. However @command{@value{AS}} has no
2239 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2240 code and warns you of the fact.
2243 Which characters are escapable, and what those escapes represent,
2244 varies widely among assemblers. The current set is what we think
2245 the BSD 4.2 assembler recognizes, and is a subset of what most C
2246 compilers recognize. If you are in doubt, do not use an escape
2250 @subsubsection Characters
2252 @cindex single character constant
2253 @cindex character, single
2254 @cindex constant, single character
2255 A single character may be written as a single quote immediately
2256 followed by that character. The same escapes apply to characters as
2257 to strings. So if you want to write the character backslash, you
2258 must write @kbd{'\\} where the first @code{\} escapes the second
2259 @code{\}. As you can see, the quote is an acute accent, not a
2260 grave accent. A newline
2262 @ifclear abnormal-separator
2263 (or semicolon @samp{;})
2265 @ifset abnormal-separator
2267 (or at sign @samp{@@})
2270 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2276 immediately following an acute accent is taken as a literal character
2277 and does not count as the end of a statement. The value of a character
2278 constant in a numeric expression is the machine's byte-wide code for
2279 that character. @command{@value{AS}} assumes your character code is ASCII:
2280 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2283 @subsection Number Constants
2285 @cindex constants, number
2286 @cindex number constants
2287 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2288 are stored in the target machine. @emph{Integers} are numbers that
2289 would fit into an @code{int} in the C language. @emph{Bignums} are
2290 integers, but they are stored in more than 32 bits. @emph{Flonums}
2291 are floating point numbers, described below.
2294 * Integers:: Integers
2299 * Bit Fields:: Bit Fields
2305 @subsubsection Integers
2307 @cindex constants, integer
2309 @cindex binary integers
2310 @cindex integers, binary
2311 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2312 the binary digits @samp{01}.
2314 @cindex octal integers
2315 @cindex integers, octal
2316 An octal integer is @samp{0} followed by zero or more of the octal
2317 digits (@samp{01234567}).
2319 @cindex decimal integers
2320 @cindex integers, decimal
2321 A decimal integer starts with a non-zero digit followed by zero or
2322 more digits (@samp{0123456789}).
2324 @cindex hexadecimal integers
2325 @cindex integers, hexadecimal
2326 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2327 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2329 Integers have the usual values. To denote a negative integer, use
2330 the prefix operator @samp{-} discussed under expressions
2331 (@pxref{Prefix Ops,,Prefix Operators}).
2334 @subsubsection Bignums
2337 @cindex constants, bignum
2338 A @dfn{bignum} has the same syntax and semantics as an integer
2339 except that the number (or its negative) takes more than 32 bits to
2340 represent in binary. The distinction is made because in some places
2341 integers are permitted while bignums are not.
2344 @subsubsection Flonums
2346 @cindex floating point numbers
2347 @cindex constants, floating point
2349 @cindex precision, floating point
2350 A @dfn{flonum} represents a floating point number. The translation is
2351 indirect: a decimal floating point number from the text is converted by
2352 @command{@value{AS}} to a generic binary floating point number of more than
2353 sufficient precision. This generic floating point number is converted
2354 to a particular computer's floating point format (or formats) by a
2355 portion of @command{@value{AS}} specialized to that computer.
2357 A flonum is written by writing (in order)
2362 (@samp{0} is optional on the HPPA.)
2366 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2368 @kbd{e} is recommended. Case is not important.
2370 @c FIXME: verify if flonum syntax really this vague for most cases
2371 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2372 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2375 On the H8/300, H8/500,
2377 and AMD 29K architectures, the letter must be
2378 one of the letters @samp{DFPRSX} (in upper or lower case).
2380 On the ARC, the letter must be one of the letters @samp{DFRS}
2381 (in upper or lower case).
2383 On the Intel 960 architecture, the letter must be
2384 one of the letters @samp{DFT} (in upper or lower case).
2386 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2390 One of the letters @samp{DFPRSX} (in upper or lower case).
2393 One of the letters @samp{DFRS} (in upper or lower case).
2396 One of the letters @samp{DFPRSX} (in upper or lower case).
2399 The letter @samp{E} (upper case only).
2402 One of the letters @samp{DFT} (in upper or lower case).
2407 An optional sign: either @samp{+} or @samp{-}.
2410 An optional @dfn{integer part}: zero or more decimal digits.
2413 An optional @dfn{fractional part}: @samp{.} followed by zero
2414 or more decimal digits.
2417 An optional exponent, consisting of:
2421 An @samp{E} or @samp{e}.
2422 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2423 @c principle this can perfectly well be different on different targets.
2425 Optional sign: either @samp{+} or @samp{-}.
2427 One or more decimal digits.
2432 At least one of the integer part or the fractional part must be
2433 present. The floating point number has the usual base-10 value.
2435 @command{@value{AS}} does all processing using integers. Flonums are computed
2436 independently of any floating point hardware in the computer running
2437 @command{@value{AS}}.
2441 @c Bit fields are written as a general facility but are also controlled
2442 @c by a conditional-compilation flag---which is as of now (21mar91)
2443 @c turned on only by the i960 config of GAS.
2445 @subsubsection Bit Fields
2448 @cindex constants, bit field
2449 You can also define numeric constants as @dfn{bit fields}.
2450 specify two numbers separated by a colon---
2452 @var{mask}:@var{value}
2455 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2458 The resulting number is then packed
2460 @c this conditional paren in case bit fields turned on elsewhere than 960
2461 (in host-dependent byte order)
2463 into a field whose width depends on which assembler directive has the
2464 bit-field as its argument. Overflow (a result from the bitwise and
2465 requiring more binary digits to represent) is not an error; instead,
2466 more constants are generated, of the specified width, beginning with the
2467 least significant digits.@refill
2469 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2470 @code{.short}, and @code{.word} accept bit-field arguments.
2475 @chapter Sections and Relocation
2480 * Secs Background:: Background
2481 * Ld Sections:: Linker Sections
2482 * As Sections:: Assembler Internal Sections
2483 * Sub-Sections:: Sub-Sections
2487 @node Secs Background
2490 Roughly, a section is a range of addresses, with no gaps; all data
2491 ``in'' those addresses is treated the same for some particular purpose.
2492 For example there may be a ``read only'' section.
2494 @cindex linker, and assembler
2495 @cindex assembler, and linker
2496 The linker @code{@value{LD}} reads many object files (partial programs) and
2497 combines their contents to form a runnable program. When @command{@value{AS}}
2498 emits an object file, the partial program is assumed to start at address 0.
2499 @code{@value{LD}} assigns the final addresses for the partial program, so that
2500 different partial programs do not overlap. This is actually an
2501 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2504 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2505 addresses. These blocks slide to their run-time addresses as rigid
2506 units; their length does not change and neither does the order of bytes
2507 within them. Such a rigid unit is called a @emph{section}. Assigning
2508 run-time addresses to sections is called @dfn{relocation}. It includes
2509 the task of adjusting mentions of object-file addresses so they refer to
2510 the proper run-time addresses.
2512 For the H8/300 and H8/500,
2513 and for the Hitachi SH,
2514 @command{@value{AS}} pads sections if needed to
2515 ensure they end on a word (sixteen bit) boundary.
2518 @cindex standard assembler sections
2519 An object file written by @command{@value{AS}} has at least three sections, any
2520 of which may be empty. These are named @dfn{text}, @dfn{data} and
2525 When it generates COFF output,
2527 @command{@value{AS}} can also generate whatever other named sections you specify
2528 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2529 If you do not use any directives that place output in the @samp{.text}
2530 or @samp{.data} sections, these sections still exist, but are empty.
2535 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2537 @command{@value{AS}} can also generate whatever other named sections you
2538 specify using the @samp{.space} and @samp{.subspace} directives. See
2539 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2540 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2541 assembler directives.
2544 Additionally, @command{@value{AS}} uses different names for the standard
2545 text, data, and bss sections when generating SOM output. Program text
2546 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2547 BSS into @samp{$BSS$}.
2551 Within the object file, the text section starts at address @code{0}, the
2552 data section follows, and the bss section follows the data section.
2555 When generating either SOM or ELF output files on the HPPA, the text
2556 section starts at address @code{0}, the data section at address
2557 @code{0x4000000}, and the bss section follows the data section.
2560 To let @code{@value{LD}} know which data changes when the sections are
2561 relocated, and how to change that data, @command{@value{AS}} also writes to the
2562 object file details of the relocation needed. To perform relocation
2563 @code{@value{LD}} must know, each time an address in the object
2567 Where in the object file is the beginning of this reference to
2570 How long (in bytes) is this reference?
2572 Which section does the address refer to? What is the numeric value of
2574 (@var{address}) @minus{} (@var{start-address of section})?
2577 Is the reference to an address ``Program-Counter relative''?
2580 @cindex addresses, format of
2581 @cindex section-relative addressing
2582 In fact, every address @command{@value{AS}} ever uses is expressed as
2584 (@var{section}) + (@var{offset into section})
2587 Further, most expressions @command{@value{AS}} computes have this section-relative
2590 (For some object formats, such as SOM for the HPPA, some expressions are
2591 symbol-relative instead.)
2594 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2595 @var{N} into section @var{secname}.''
2597 Apart from text, data and bss sections you need to know about the
2598 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2599 addresses in the absolute section remain unchanged. For example, address
2600 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2601 @code{@value{LD}}. Although the linker never arranges two partial programs'
2602 data sections with overlapping addresses after linking, @emph{by definition}
2603 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2604 part of a program is always the same address when the program is running as
2605 address @code{@{absolute@ 239@}} in any other part of the program.
2607 The idea of sections is extended to the @dfn{undefined} section. Any
2608 address whose section is unknown at assembly time is by definition
2609 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2610 Since numbers are always defined, the only way to generate an undefined
2611 address is to mention an undefined symbol. A reference to a named
2612 common block would be such a symbol: its value is unknown at assembly
2613 time so it has section @emph{undefined}.
2615 By analogy the word @emph{section} is used to describe groups of sections in
2616 the linked program. @code{@value{LD}} puts all partial programs' text
2617 sections in contiguous addresses in the linked program. It is
2618 customary to refer to the @emph{text section} of a program, meaning all
2619 the addresses of all partial programs' text sections. Likewise for
2620 data and bss sections.
2622 Some sections are manipulated by @code{@value{LD}}; others are invented for
2623 use of @command{@value{AS}} and have no meaning except during assembly.
2626 @section Linker Sections
2627 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2632 @cindex named sections
2633 @cindex sections, named
2634 @item named sections
2637 @cindex text section
2638 @cindex data section
2642 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2643 separate but equal sections. Anything you can say of one section is
2646 When the program is running, however, it is
2647 customary for the text section to be unalterable. The
2648 text section is often shared among processes: it contains
2649 instructions, constants and the like. The data section of a running
2650 program is usually alterable: for example, C variables would be stored
2651 in the data section.
2656 This section contains zeroed bytes when your program begins running. It
2657 is used to hold uninitialized variables or common storage. The length of
2658 each partial program's bss section is important, but because it starts
2659 out containing zeroed bytes there is no need to store explicit zero
2660 bytes in the object file. The bss section was invented to eliminate
2661 those explicit zeros from object files.
2663 @cindex absolute section
2664 @item absolute section
2665 Address 0 of this section is always ``relocated'' to runtime address 0.
2666 This is useful if you want to refer to an address that @code{@value{LD}} must
2667 not change when relocating. In this sense we speak of absolute
2668 addresses being ``unrelocatable'': they do not change during relocation.
2670 @cindex undefined section
2671 @item undefined section
2672 This ``section'' is a catch-all for address references to objects not in
2673 the preceding sections.
2674 @c FIXME: ref to some other doc on obj-file formats could go here.
2677 @cindex relocation example
2678 An idealized example of three relocatable sections follows.
2680 The example uses the traditional section names @samp{.text} and @samp{.data}.
2682 Memory addresses are on the horizontal axis.
2686 @c END TEXI2ROFF-KILL
2689 partial program # 1: |ttttt|dddd|00|
2696 partial program # 2: |TTT|DDD|000|
2699 +--+---+-----+--+----+---+-----+~~
2700 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2701 +--+---+-----+--+----+---+-----+~~
2703 addresses: 0 @dots{}
2710 \line{\it Partial program \#1: \hfil}
2711 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2712 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2714 \line{\it Partial program \#2: \hfil}
2715 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2716 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2718 \line{\it linked program: \hfil}
2719 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2720 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2721 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2722 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2724 \line{\it addresses: \hfil}
2728 @c END TEXI2ROFF-KILL
2731 @section Assembler Internal Sections
2733 @cindex internal assembler sections
2734 @cindex sections in messages, internal
2735 These sections are meant only for the internal use of @command{@value{AS}}. They
2736 have no meaning at run-time. You do not really need to know about these
2737 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2738 warning messages, so it might be helpful to have an idea of their
2739 meanings to @command{@value{AS}}. These sections are used to permit the
2740 value of every expression in your assembly language program to be a
2741 section-relative address.
2744 @cindex assembler internal logic error
2745 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2746 An internal assembler logic error has been found. This means there is a
2747 bug in the assembler.
2749 @cindex expr (internal section)
2751 The assembler stores complex expression internally as combinations of
2752 symbols. When it needs to represent an expression as a symbol, it puts
2753 it in the expr section.
2755 @c FIXME item transfer[t] vector preload
2756 @c FIXME item transfer[t] vector postload
2757 @c FIXME item register
2761 @section Sub-Sections
2763 @cindex numbered subsections
2764 @cindex grouping data
2770 fall into two sections: text and data.
2772 You may have separate groups of
2774 data in named sections
2778 data in named sections
2784 that you want to end up near to each other in the object file, even though they
2785 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2786 use @dfn{subsections} for this purpose. Within each section, there can be
2787 numbered subsections with values from 0 to 8192. Objects assembled into the
2788 same subsection go into the object file together with other objects in the same
2789 subsection. For example, a compiler might want to store constants in the text
2790 section, but might not want to have them interspersed with the program being
2791 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2792 section of code being output, and a @samp{.text 1} before each group of
2793 constants being output.
2795 Subsections are optional. If you do not use subsections, everything
2796 goes in subsection number zero.
2799 Each subsection is zero-padded up to a multiple of four bytes.
2800 (Subsections may be padded a different amount on different flavors
2801 of @command{@value{AS}}.)
2805 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2806 boundary (two bytes).
2807 The same is true on the Hitachi SH.
2810 @c FIXME section padding (alignment)?
2811 @c Rich Pixley says padding here depends on target obj code format; that
2812 @c doesn't seem particularly useful to say without further elaboration,
2813 @c so for now I say nothing about it. If this is a generic BFD issue,
2814 @c these paragraphs might need to vanish from this manual, and be
2815 @c discussed in BFD chapter of binutils (or some such).
2818 On the AMD 29K family, no particular padding is added to section or
2819 subsection sizes; @value{AS} forces no alignment on this platform.
2823 Subsections appear in your object file in numeric order, lowest numbered
2824 to highest. (All this to be compatible with other people's assemblers.)
2825 The object file contains no representation of subsections; @code{@value{LD}} and
2826 other programs that manipulate object files see no trace of them.
2827 They just see all your text subsections as a text section, and all your
2828 data subsections as a data section.
2830 To specify which subsection you want subsequent statements assembled
2831 into, use a numeric argument to specify it, in a @samp{.text
2832 @var{expression}} or a @samp{.data @var{expression}} statement.
2835 When generating COFF output, you
2840 can also use an extra subsection
2841 argument with arbitrary named sections: @samp{.section @var{name},
2844 @var{Expression} should be an absolute expression.
2845 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2846 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2847 begins in @code{text 0}. For instance:
2849 .text 0 # The default subsection is text 0 anyway.
2850 .ascii "This lives in the first text subsection. *"
2852 .ascii "But this lives in the second text subsection."
2854 .ascii "This lives in the data section,"
2855 .ascii "in the first data subsection."
2857 .ascii "This lives in the first text section,"
2858 .ascii "immediately following the asterisk (*)."
2861 Each section has a @dfn{location counter} incremented by one for every byte
2862 assembled into that section. Because subsections are merely a convenience
2863 restricted to @command{@value{AS}} there is no concept of a subsection location
2864 counter. There is no way to directly manipulate a location counter---but the
2865 @code{.align} directive changes it, and any label definition captures its
2866 current value. The location counter of the section where statements are being
2867 assembled is said to be the @dfn{active} location counter.
2870 @section bss Section
2873 @cindex common variable storage
2874 The bss section is used for local common variable storage.
2875 You may allocate address space in the bss section, but you may
2876 not dictate data to load into it before your program executes. When
2877 your program starts running, all the contents of the bss
2878 section are zeroed bytes.
2880 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2881 @ref{Lcomm,,@code{.lcomm}}.
2883 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2884 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2887 When assembling for a target which supports multiple sections, such as ELF or
2888 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2889 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2890 section. Typically the section will only contain symbol definitions and
2891 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2898 Symbols are a central concept: the programmer uses symbols to name
2899 things, the linker uses symbols to link, and the debugger uses symbols
2903 @cindex debuggers, and symbol order
2904 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2905 the same order they were declared. This may break some debuggers.
2910 * Setting Symbols:: Giving Symbols Other Values
2911 * Symbol Names:: Symbol Names
2912 * Dot:: The Special Dot Symbol
2913 * Symbol Attributes:: Symbol Attributes
2920 A @dfn{label} is written as a symbol immediately followed by a colon
2921 @samp{:}. The symbol then represents the current value of the
2922 active location counter, and is, for example, a suitable instruction
2923 operand. You are warned if you use the same symbol to represent two
2924 different locations: the first definition overrides any other
2928 On the HPPA, the usual form for a label need not be immediately followed by a
2929 colon, but instead must start in column zero. Only one label may be defined on
2930 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2931 provides a special directive @code{.label} for defining labels more flexibly.
2934 @node Setting Symbols
2935 @section Giving Symbols Other Values
2937 @cindex assigning values to symbols
2938 @cindex symbol values, assigning
2939 A symbol can be given an arbitrary value by writing a symbol, followed
2940 by an equals sign @samp{=}, followed by an expression
2941 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2942 directive. @xref{Set,,@code{.set}}.
2945 @section Symbol Names
2947 @cindex symbol names
2948 @cindex names, symbol
2949 @ifclear SPECIAL-SYMS
2950 Symbol names begin with a letter or with one of @samp{._}. On most
2951 machines, you can also use @code{$} in symbol names; exceptions are
2952 noted in @ref{Machine Dependencies}. That character may be followed by any
2953 string of digits, letters, dollar signs (unless otherwise noted in
2954 @ref{Machine Dependencies}), and underscores.
2957 For the AMD 29K family, @samp{?} is also allowed in the
2958 body of a symbol name, though not at its beginning.
2963 Symbol names begin with a letter or with one of @samp{._}. On the
2965 H8/500, you can also use @code{$} in symbol names. That character may
2966 be followed by any string of digits, letters, dollar signs (save on the
2967 H8/300), and underscores.
2971 Case of letters is significant: @code{foo} is a different symbol name
2974 Each symbol has exactly one name. Each name in an assembly language program
2975 refers to exactly one symbol. You may use that symbol name any number of times
2978 @subheading Local Symbol Names
2980 @cindex local symbol names
2981 @cindex symbol names, local
2982 @cindex temporary symbol names
2983 @cindex symbol names, temporary
2984 Local symbols help compilers and programmers use names temporarily.
2985 They create symbols which are guaranteed to be unique over the entire scope of
2986 the input source code and which can be referred to by a simple notation.
2987 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
2988 represents any positive integer). To refer to the most recent previous
2989 definition of that symbol write @samp{@b{N}b}, using the same number as when
2990 you defined the label. To refer to the next definition of a local label, write
2991 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
2994 There is no restriction on how you can use these labels, and you can reuse them
2995 too. So that it is possible to repeatedly define the same local label (using
2996 the same number @samp{@b{N}}), although you can only refer to the most recently
2997 defined local label of that number (for a backwards reference) or the next
2998 definition of a specific local label for a forward reference. It is also worth
2999 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3000 implemented in a slightly more efficient manner than the others.
3011 Which is the equivalent of:
3014 label_1: branch label_3
3015 label_2: branch label_1
3016 label_3: branch label_4
3017 label_4: branch label_3
3020 Local symbol names are only a notational device. They are immediately
3021 transformed into more conventional symbol names before the assembler uses them.
3022 The symbol names stored in the symbol table, appearing in error messages and
3023 optionally emitted to the object file. The names are constructed using these
3028 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3029 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3030 used for symbols you are never intended to see. If you use the
3031 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3032 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3033 you may use them in debugging.
3036 This is the number that was used in the local label definition. So if the
3037 label is written @samp{55:} then the number is @samp{55}.
3040 This unusual character is included so you do not accidentally invent a symbol
3041 of the same name. The character has ASCII value of @samp{\002} (control-B).
3043 @item @emph{ordinal number}
3044 This is a serial number to keep the labels distinct. The first definition of
3045 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3046 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3047 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3050 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3051 @code{3:} is named @code{L3@kbd{C-B}44}.
3053 @subheading Dollar Local Labels
3054 @cindex dollar local symbols
3056 @code{@value{AS}} also supports an even more local form of local labels called
3057 dollar labels. These labels go out of scope (ie they become undefined) as soon
3058 as a non-local label is defined. Thus they remain valid for only a small
3059 region of the input source code. Normal local labels, by contrast, remain in
3060 scope for the entire file, or until they are redefined by another occurrence of
3061 the same local label.
3063 Dollar labels are defined in exactly the same way as ordinary local labels,
3064 except that instead of being terminated by a colon, they are terminated by a
3065 dollar sign. eg @samp{@b{55$}}.
3067 They can also be distinguished from ordinary local labels by their transformed
3068 name which uses ASCII character @samp{\001} (control-A) as the magic character
3069 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3070 is named @samp{L6@kbd{C-A}5}.
3073 @section The Special Dot Symbol
3075 @cindex dot (symbol)
3076 @cindex @code{.} (symbol)
3077 @cindex current address
3078 @cindex location counter
3079 The special symbol @samp{.} refers to the current address that
3080 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3081 .long .} defines @code{melvin} to contain its own address.
3082 Assigning a value to @code{.} is treated the same as a @code{.org}
3083 directive. Thus, the expression @samp{.=.+4} is the same as saying
3084 @ifclear no-space-dir
3093 @node Symbol Attributes
3094 @section Symbol Attributes
3096 @cindex symbol attributes
3097 @cindex attributes, symbol
3098 Every symbol has, as well as its name, the attributes ``Value'' and
3099 ``Type''. Depending on output format, symbols can also have auxiliary
3102 The detailed definitions are in @file{a.out.h}.
3105 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3106 all these attributes, and probably won't warn you. This makes the
3107 symbol an externally defined symbol, which is generally what you
3111 * Symbol Value:: Value
3112 * Symbol Type:: Type
3115 * a.out Symbols:: Symbol Attributes: @code{a.out}
3119 * a.out Symbols:: Symbol Attributes: @code{a.out}
3122 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3127 * COFF Symbols:: Symbol Attributes for COFF
3130 * SOM Symbols:: Symbol Attributes for SOM
3137 @cindex value of a symbol
3138 @cindex symbol value
3139 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3140 location in the text, data, bss or absolute sections the value is the
3141 number of addresses from the start of that section to the label.
3142 Naturally for text, data and bss sections the value of a symbol changes
3143 as @code{@value{LD}} changes section base addresses during linking. Absolute
3144 symbols' values do not change during linking: that is why they are
3147 The value of an undefined symbol is treated in a special way. If it is
3148 0 then the symbol is not defined in this assembler source file, and
3149 @code{@value{LD}} tries to determine its value from other files linked into the
3150 same program. You make this kind of symbol simply by mentioning a symbol
3151 name without defining it. A non-zero value represents a @code{.comm}
3152 common declaration. The value is how much common storage to reserve, in
3153 bytes (addresses). The symbol refers to the first address of the
3159 @cindex type of a symbol
3161 The type attribute of a symbol contains relocation (section)
3162 information, any flag settings indicating that a symbol is external, and
3163 (optionally), other information for linkers and debuggers. The exact
3164 format depends on the object-code output format in use.
3169 @c The following avoids a "widow" subsection title. @group would be
3170 @c better if it were available outside examples.
3173 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3175 @cindex @code{b.out} symbol attributes
3176 @cindex symbol attributes, @code{b.out}
3177 These symbol attributes appear only when @command{@value{AS}} is configured for
3178 one of the Berkeley-descended object output formats---@code{a.out} or
3184 @subsection Symbol Attributes: @code{a.out}
3186 @cindex @code{a.out} symbol attributes
3187 @cindex symbol attributes, @code{a.out}
3193 @subsection Symbol Attributes: @code{a.out}
3195 @cindex @code{a.out} symbol attributes
3196 @cindex symbol attributes, @code{a.out}
3200 * Symbol Desc:: Descriptor
3201 * Symbol Other:: Other
3205 @subsubsection Descriptor
3207 @cindex descriptor, of @code{a.out} symbol
3208 This is an arbitrary 16-bit value. You may establish a symbol's
3209 descriptor value by using a @code{.desc} statement
3210 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3211 @command{@value{AS}}.
3214 @subsubsection Other
3216 @cindex other attribute, of @code{a.out} symbol
3217 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3222 @subsection Symbol Attributes for COFF
3224 @cindex COFF symbol attributes
3225 @cindex symbol attributes, COFF
3227 The COFF format supports a multitude of auxiliary symbol attributes;
3228 like the primary symbol attributes, they are set between @code{.def} and
3229 @code{.endef} directives.
3231 @subsubsection Primary Attributes
3233 @cindex primary attributes, COFF symbols
3234 The symbol name is set with @code{.def}; the value and type,
3235 respectively, with @code{.val} and @code{.type}.
3237 @subsubsection Auxiliary Attributes
3239 @cindex auxiliary attributes, COFF symbols
3240 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3241 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3242 information for COFF.
3247 @subsection Symbol Attributes for SOM
3249 @cindex SOM symbol attributes
3250 @cindex symbol attributes, SOM
3252 The SOM format for the HPPA supports a multitude of symbol attributes set with
3253 the @code{.EXPORT} and @code{.IMPORT} directives.
3255 The attributes are described in @cite{HP9000 Series 800 Assembly
3256 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3257 @code{EXPORT} assembler directive documentation.
3261 @chapter Expressions
3265 @cindex numeric values
3266 An @dfn{expression} specifies an address or numeric value.
3267 Whitespace may precede and/or follow an expression.
3269 The result of an expression must be an absolute number, or else an offset into
3270 a particular section. If an expression is not absolute, and there is not
3271 enough information when @command{@value{AS}} sees the expression to know its
3272 section, a second pass over the source program might be necessary to interpret
3273 the expression---but the second pass is currently not implemented.
3274 @command{@value{AS}} aborts with an error message in this situation.
3277 * Empty Exprs:: Empty Expressions
3278 * Integer Exprs:: Integer Expressions
3282 @section Empty Expressions
3284 @cindex empty expressions
3285 @cindex expressions, empty
3286 An empty expression has no value: it is just whitespace or null.
3287 Wherever an absolute expression is required, you may omit the
3288 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3289 is compatible with other assemblers.
3292 @section Integer Expressions
3294 @cindex integer expressions
3295 @cindex expressions, integer
3296 An @dfn{integer expression} is one or more @emph{arguments} delimited
3297 by @emph{operators}.
3300 * Arguments:: Arguments
3301 * Operators:: Operators
3302 * Prefix Ops:: Prefix Operators
3303 * Infix Ops:: Infix Operators
3307 @subsection Arguments
3309 @cindex expression arguments
3310 @cindex arguments in expressions
3311 @cindex operands in expressions
3312 @cindex arithmetic operands
3313 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3314 contexts arguments are sometimes called ``arithmetic operands''. In
3315 this manual, to avoid confusing them with the ``instruction operands'' of
3316 the machine language, we use the term ``argument'' to refer to parts of
3317 expressions only, reserving the word ``operand'' to refer only to machine
3318 instruction operands.
3320 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3321 @var{section} is one of text, data, bss, absolute,
3322 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3325 Numbers are usually integers.
3327 A number can be a flonum or bignum. In this case, you are warned
3328 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3329 these 32 bits are an integer. You may write integer-manipulating
3330 instructions that act on exotic constants, compatible with other
3333 @cindex subexpressions
3334 Subexpressions are a left parenthesis @samp{(} followed by an integer
3335 expression, followed by a right parenthesis @samp{)}; or a prefix
3336 operator followed by an argument.
3339 @subsection Operators
3341 @cindex operators, in expressions
3342 @cindex arithmetic functions
3343 @cindex functions, in expressions
3344 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3345 operators are followed by an argument. Infix operators appear
3346 between their arguments. Operators may be preceded and/or followed by
3350 @subsection Prefix Operator
3352 @cindex prefix operators
3353 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3354 one argument, which must be absolute.
3356 @c the tex/end tex stuff surrounding this small table is meant to make
3357 @c it align, on the printed page, with the similar table in the next
3358 @c section (which is inside an enumerate).
3360 \global\advance\leftskip by \itemindent
3365 @dfn{Negation}. Two's complement negation.
3367 @dfn{Complementation}. Bitwise not.
3371 \global\advance\leftskip by -\itemindent
3375 @subsection Infix Operators
3377 @cindex infix operators
3378 @cindex operators, permitted arguments
3379 @dfn{Infix operators} take two arguments, one on either side. Operators
3380 have precedence, but operations with equal precedence are performed left
3381 to right. Apart from @code{+} or @option{-}, both arguments must be
3382 absolute, and the result is absolute.
3385 @cindex operator precedence
3386 @cindex precedence of operators
3393 @dfn{Multiplication}.
3396 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3403 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3407 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3411 Intermediate precedence
3416 @dfn{Bitwise Inclusive Or}.
3422 @dfn{Bitwise Exclusive Or}.
3425 @dfn{Bitwise Or Not}.
3432 @cindex addition, permitted arguments
3433 @cindex plus, permitted arguments
3434 @cindex arguments for addition
3436 @dfn{Addition}. If either argument is absolute, the result has the section of
3437 the other argument. You may not add together arguments from different
3440 @cindex subtraction, permitted arguments
3441 @cindex minus, permitted arguments
3442 @cindex arguments for subtraction
3444 @dfn{Subtraction}. If the right argument is absolute, the
3445 result has the section of the left argument.
3446 If both arguments are in the same section, the result is absolute.
3447 You may not subtract arguments from different sections.
3448 @c FIXME is there still something useful to say about undefined - undefined ?
3450 @cindex comparison expressions
3451 @cindex expressions, comparison
3455 @dfn{Is Not Equal To}
3459 @dfn{Is Greater Than}
3461 @dfn{Is Greater Than Or Equal To}
3463 @dfn{Is Less Than Or Equal To}
3465 The comparison operators can be used as infix operators. A true results has a
3466 value of -1 whereas a false result has a value of 0. Note, these operators
3467 perform signed comparisons.
3470 @item Lowest Precedence
3479 These two logical operations can be used to combine the results of sub
3480 expressions. Note, unlike the comparison operators a true result returns a
3481 value of 1 but a false results does still return 0. Also note that the logical
3482 or operator has a slightly lower precedence than logical and.
3487 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3488 address; you can only have a defined section in one of the two arguments.
3491 @chapter Assembler Directives
3493 @cindex directives, machine independent
3494 @cindex pseudo-ops, machine independent
3495 @cindex machine independent directives
3496 All assembler directives have names that begin with a period (@samp{.}).
3497 The rest of the name is letters, usually in lower case.
3499 This chapter discusses directives that are available regardless of the
3500 target machine configuration for the @sc{gnu} assembler.
3502 Some machine configurations provide additional directives.
3503 @xref{Machine Dependencies}.
3506 @ifset machine-directives
3507 @xref{Machine Dependencies} for additional directives.
3512 * Abort:: @code{.abort}
3514 * ABORT:: @code{.ABORT}
3517 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3518 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3519 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3520 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3521 * Byte:: @code{.byte @var{expressions}}
3522 * Comm:: @code{.comm @var{symbol} , @var{length} }
3523 * Data:: @code{.data @var{subsection}}
3525 * Def:: @code{.def @var{name}}
3528 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3534 * Double:: @code{.double @var{flonums}}
3535 * Eject:: @code{.eject}
3536 * Else:: @code{.else}
3537 * Elseif:: @code{.elseif}
3540 * Endef:: @code{.endef}
3543 * Endfunc:: @code{.endfunc}
3544 * Endif:: @code{.endif}
3545 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3546 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3548 * Exitm:: @code{.exitm}
3549 * Extern:: @code{.extern}
3550 * Fail:: @code{.fail}
3551 @ifclear no-file-dir
3552 * File:: @code{.file @var{string}}
3555 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3556 * Float:: @code{.float @var{flonums}}
3557 * Func:: @code{.func}
3558 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3560 * Hidden:: @code{.hidden @var{names}}
3563 * hword:: @code{.hword @var{expressions}}
3564 * Ident:: @code{.ident}
3565 * If:: @code{.if @var{absolute expression}}
3566 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3567 * Include:: @code{.include "@var{file}"}
3568 * Int:: @code{.int @var{expressions}}
3570 * Internal:: @code{.internal @var{names}}
3573 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3574 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3575 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3576 * Lflags:: @code{.lflags}
3577 @ifclear no-line-dir
3578 * Line:: @code{.line @var{line-number}}
3581 * Ln:: @code{.ln @var{line-number}}
3582 * Linkonce:: @code{.linkonce [@var{type}]}
3583 * List:: @code{.list}
3584 * Long:: @code{.long @var{expressions}}
3586 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3589 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3590 * MRI:: @code{.mri @var{val}}
3591 * Nolist:: @code{.nolist}
3592 * Octa:: @code{.octa @var{bignums}}
3593 * Org:: @code{.org @var{new-lc} , @var{fill}}
3594 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3596 * PopSection:: @code{.popsection}
3597 * Previous:: @code{.previous}
3600 * Print:: @code{.print @var{string}}
3602 * Protected:: @code{.protected @var{names}}
3605 * Psize:: @code{.psize @var{lines}, @var{columns}}
3606 * Purgem:: @code{.purgem @var{name}}
3608 * PushSection:: @code{.pushsection @var{name}}
3611 * Quad:: @code{.quad @var{bignums}}
3612 * Rept:: @code{.rept @var{count}}
3613 * Sbttl:: @code{.sbttl "@var{subheading}"}
3615 * Scl:: @code{.scl @var{class}}
3616 * Section:: @code{.section @var{name}, @var{subsection}}
3619 * Set:: @code{.set @var{symbol}, @var{expression}}
3620 * Short:: @code{.short @var{expressions}}
3621 * Single:: @code{.single @var{flonums}}
3622 * Size:: @code{.size [@var{name} , @var{expression}]}
3623 * Skip:: @code{.skip @var{size} , @var{fill}}
3624 * Sleb128:: @code{.sleb128 @var{expressions}}
3625 * Space:: @code{.space @var{size} , @var{fill}}
3627 * Stab:: @code{.stabd, .stabn, .stabs}
3630 * String:: @code{.string "@var{str}"}
3631 * Struct:: @code{.struct @var{expression}}
3633 * SubSection:: @code{.subsection}
3634 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3638 * Tag:: @code{.tag @var{structname}}
3641 * Text:: @code{.text @var{subsection}}
3642 * Title:: @code{.title "@var{heading}"}
3643 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3644 * Uleb128:: @code{.uleb128 @var{expressions}}
3646 * Val:: @code{.val @var{addr}}
3650 * Version:: @code{.version "@var{string}"}
3651 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3652 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3653 * Weak:: @code{.weak @var{names}}
3656 * Word:: @code{.word @var{expressions}}
3657 * Deprecated:: Deprecated Directives
3661 @section @code{.abort}
3663 @cindex @code{abort} directive
3664 @cindex stopping the assembly
3665 This directive stops the assembly immediately. It is for
3666 compatibility with other assemblers. The original idea was that the
3667 assembly language source would be piped into the assembler. If the sender
3668 of the source quit, it could use this directive tells @command{@value{AS}} to
3669 quit also. One day @code{.abort} will not be supported.
3673 @section @code{.ABORT}
3675 @cindex @code{ABORT} directive
3676 When producing COFF output, @command{@value{AS}} accepts this directive as a
3677 synonym for @samp{.abort}.
3680 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3686 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3688 @cindex padding the location counter
3689 @cindex @code{align} directive
3690 Pad the location counter (in the current subsection) to a particular storage
3691 boundary. The first expression (which must be absolute) is the alignment
3692 required, as described below.
3694 The second expression (also absolute) gives the fill value to be stored in the
3695 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3696 padding bytes are normally zero. However, on some systems, if the section is
3697 marked as containing code and the fill value is omitted, the space is filled
3698 with no-op instructions.
3700 The third expression is also absolute, and is also optional. If it is present,
3701 it is the maximum number of bytes that should be skipped by this alignment
3702 directive. If doing the alignment would require skipping more bytes than the
3703 specified maximum, then the alignment is not done at all. You can omit the
3704 fill value (the second argument) entirely by simply using two commas after the
3705 required alignment; this can be useful if you want the alignment to be filled
3706 with no-op instructions when appropriate.
3708 The way the required alignment is specified varies from system to system.
3709 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3711 the first expression is the
3712 alignment request in bytes. For example @samp{.align 8} advances
3713 the location counter until it is a multiple of 8. If the location counter
3714 is already a multiple of 8, no change is needed.
3716 For other systems, including the i386 using a.out format, and the arm and
3717 strongarm, it is the
3718 number of low-order zero bits the location counter must have after
3719 advancement. For example @samp{.align 3} advances the location
3720 counter until it a multiple of 8. If the location counter is already a
3721 multiple of 8, no change is needed.
3723 This inconsistency is due to the different behaviors of the various
3724 native assemblers for these systems which GAS must emulate.
3725 GAS also provides @code{.balign} and @code{.p2align} directives,
3726 described later, which have a consistent behavior across all
3727 architectures (but are specific to GAS).
3730 @section @code{.ascii "@var{string}"}@dots{}
3732 @cindex @code{ascii} directive
3733 @cindex string literals
3734 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3735 separated by commas. It assembles each string (with no automatic
3736 trailing zero byte) into consecutive addresses.
3739 @section @code{.asciz "@var{string}"}@dots{}
3741 @cindex @code{asciz} directive
3742 @cindex zero-terminated strings
3743 @cindex null-terminated strings
3744 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3745 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3748 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3750 @cindex padding the location counter given number of bytes
3751 @cindex @code{balign} directive
3752 Pad the location counter (in the current subsection) to a particular
3753 storage boundary. The first expression (which must be absolute) is the
3754 alignment request in bytes. For example @samp{.balign 8} advances
3755 the location counter until it is a multiple of 8. If the location counter
3756 is already a multiple of 8, no change is needed.
3758 The second expression (also absolute) gives the fill value to be stored in the
3759 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3760 padding bytes are normally zero. However, on some systems, if the section is
3761 marked as containing code and the fill value is omitted, the space is filled
3762 with no-op instructions.
3764 The third expression is also absolute, and is also optional. If it is present,
3765 it is the maximum number of bytes that should be skipped by this alignment
3766 directive. If doing the alignment would require skipping more bytes than the
3767 specified maximum, then the alignment is not done at all. You can omit the
3768 fill value (the second argument) entirely by simply using two commas after the
3769 required alignment; this can be useful if you want the alignment to be filled
3770 with no-op instructions when appropriate.
3772 @cindex @code{balignw} directive
3773 @cindex @code{balignl} directive
3774 The @code{.balignw} and @code{.balignl} directives are variants of the
3775 @code{.balign} directive. The @code{.balignw} directive treats the fill
3776 pattern as a two byte word value. The @code{.balignl} directives treats the
3777 fill pattern as a four byte longword value. For example, @code{.balignw
3778 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3779 filled in with the value 0x368d (the exact placement of the bytes depends upon
3780 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3784 @section @code{.byte @var{expressions}}
3786 @cindex @code{byte} directive
3787 @cindex integers, one byte
3788 @code{.byte} expects zero or more expressions, separated by commas.
3789 Each expression is assembled into the next byte.
3792 @section @code{.comm @var{symbol} , @var{length} }
3794 @cindex @code{comm} directive
3795 @cindex symbol, common
3796 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3797 common symbol in one object file may be merged with a defined or common symbol
3798 of the same name in another object file. If @code{@value{LD}} does not see a
3799 definition for the symbol--just one or more common symbols--then it will
3800 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3801 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3802 the same name, and they do not all have the same size, it will allocate space
3803 using the largest size.
3806 When using ELF, the @code{.comm} directive takes an optional third argument.
3807 This is the desired alignment of the symbol, specified as a byte boundary (for
3808 example, an alignment of 16 means that the least significant 4 bits of the
3809 address should be zero). The alignment must be an absolute expression, and it
3810 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3811 for the common symbol, it will use the alignment when placing the symbol. If
3812 no alignment is specified, @command{@value{AS}} will set the alignment to the
3813 largest power of two less than or equal to the size of the symbol, up to a
3818 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3819 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3823 @section @code{.data @var{subsection}}
3825 @cindex @code{data} directive
3826 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3827 end of the data subsection numbered @var{subsection} (which is an
3828 absolute expression). If @var{subsection} is omitted, it defaults
3833 @section @code{.def @var{name}}
3835 @cindex @code{def} directive
3836 @cindex COFF symbols, debugging
3837 @cindex debugging COFF symbols
3838 Begin defining debugging information for a symbol @var{name}; the
3839 definition extends until the @code{.endef} directive is encountered.
3842 This directive is only observed when @command{@value{AS}} is configured for COFF
3843 format output; when producing @code{b.out}, @samp{.def} is recognized,
3850 @section @code{.desc @var{symbol}, @var{abs-expression}}
3852 @cindex @code{desc} directive
3853 @cindex COFF symbol descriptor
3854 @cindex symbol descriptor, COFF
3855 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3856 to the low 16 bits of an absolute expression.
3859 The @samp{.desc} directive is not available when @command{@value{AS}} is
3860 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3861 object format. For the sake of compatibility, @command{@value{AS}} accepts
3862 it, but produces no output, when configured for COFF.
3868 @section @code{.dim}
3870 @cindex @code{dim} directive
3871 @cindex COFF auxiliary symbol information
3872 @cindex auxiliary symbol information, COFF
3873 This directive is generated by compilers to include auxiliary debugging
3874 information in the symbol table. It is only permitted inside
3875 @code{.def}/@code{.endef} pairs.
3878 @samp{.dim} is only meaningful when generating COFF format output; when
3879 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3885 @section @code{.double @var{flonums}}
3887 @cindex @code{double} directive
3888 @cindex floating point numbers (double)
3889 @code{.double} expects zero or more flonums, separated by commas. It
3890 assembles floating point numbers.
3892 The exact kind of floating point numbers emitted depends on how
3893 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3897 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3898 in @sc{ieee} format.
3903 @section @code{.eject}
3905 @cindex @code{eject} directive
3906 @cindex new page, in listings
3907 @cindex page, in listings
3908 @cindex listing control: new page
3909 Force a page break at this point, when generating assembly listings.
3912 @section @code{.else}
3914 @cindex @code{else} directive
3915 @code{.else} is part of the @command{@value{AS}} support for conditional
3916 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3917 of code to be assembled if the condition for the preceding @code{.if}
3921 @section @code{.elseif}
3923 @cindex @code{elseif} directive
3924 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3925 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3926 @code{.if} block that would otherwise fill the entire @code{.else} section.
3929 @section @code{.end}
3931 @cindex @code{end} directive
3932 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3933 process anything in the file past the @code{.end} directive.
3937 @section @code{.endef}
3939 @cindex @code{endef} directive
3940 This directive flags the end of a symbol definition begun with
3944 @samp{.endef} is only meaningful when generating COFF format output; if
3945 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3946 directive but ignores it.
3951 @section @code{.endfunc}
3952 @cindex @code{endfunc} directive
3953 @code{.endfunc} marks the end of a function specified with @code{.func}.
3956 @section @code{.endif}
3958 @cindex @code{endif} directive
3959 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3960 it marks the end of a block of code that is only assembled
3961 conditionally. @xref{If,,@code{.if}}.
3964 @section @code{.equ @var{symbol}, @var{expression}}
3966 @cindex @code{equ} directive
3967 @cindex assigning values to symbols
3968 @cindex symbols, assigning values to
3969 This directive sets the value of @var{symbol} to @var{expression}.
3970 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3973 The syntax for @code{equ} on the HPPA is
3974 @samp{@var{symbol} .equ @var{expression}}.
3978 @section @code{.equiv @var{symbol}, @var{expression}}
3979 @cindex @code{equiv} directive
3980 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3981 the assembler will signal an error if @var{symbol} is already defined.
3983 Except for the contents of the error message, this is roughly equivalent to
3992 @section @code{.err}
3993 @cindex @code{err} directive
3994 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
3995 message and, unless the @option{-Z} option was used, it will not generate an
3996 object file. This can be used to signal error an conditionally compiled code.
3999 @section @code{.exitm}
4000 Exit early from the current macro definition. @xref{Macro}.
4003 @section @code{.extern}
4005 @cindex @code{extern} directive
4006 @code{.extern} is accepted in the source program---for compatibility
4007 with other assemblers---but it is ignored. @command{@value{AS}} treats
4008 all undefined symbols as external.
4011 @section @code{.fail @var{expression}}
4013 @cindex @code{fail} directive
4014 Generates an error or a warning. If the value of the @var{expression} is 500
4015 or more, @command{@value{AS}} will print a warning message. If the value is less
4016 than 500, @command{@value{AS}} will print an error message. The message will
4017 include the value of @var{expression}. This can occasionally be useful inside
4018 complex nested macros or conditional assembly.
4020 @ifclear no-file-dir
4022 @section @code{.file @var{string}}
4024 @cindex @code{file} directive
4025 @cindex logical file name
4026 @cindex file name, logical
4027 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4028 file. @var{string} is the new file name. In general, the filename is
4029 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4030 to specify an empty file name, you must give the quotes--@code{""}. This
4031 statement may go away in future: it is only recognized to be compatible with
4032 old @command{@value{AS}} programs.
4034 In some configurations of @command{@value{AS}}, @code{.file} has already been
4035 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4040 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4042 @cindex @code{fill} directive
4043 @cindex writing patterns in memory
4044 @cindex patterns, writing in memory
4045 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4046 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4047 may be zero or more. @var{Size} may be zero or more, but if it is
4048 more than 8, then it is deemed to have the value 8, compatible with
4049 other people's assemblers. The contents of each @var{repeat} bytes
4050 is taken from an 8-byte number. The highest order 4 bytes are
4051 zero. The lowest order 4 bytes are @var{value} rendered in the
4052 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4053 Each @var{size} bytes in a repetition is taken from the lowest order
4054 @var{size} bytes of this number. Again, this bizarre behavior is
4055 compatible with other people's assemblers.
4057 @var{size} and @var{value} are optional.
4058 If the second comma and @var{value} are absent, @var{value} is
4059 assumed zero. If the first comma and following tokens are absent,
4060 @var{size} is assumed to be 1.
4063 @section @code{.float @var{flonums}}
4065 @cindex floating point numbers (single)
4066 @cindex @code{float} directive
4067 This directive assembles zero or more flonums, separated by commas. It
4068 has the same effect as @code{.single}.
4070 The exact kind of floating point numbers emitted depends on how
4071 @command{@value{AS}} is configured.
4072 @xref{Machine Dependencies}.
4076 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4077 in @sc{ieee} format.
4082 @section @code{.func @var{name}[,@var{label}]}
4083 @cindex @code{func} directive
4084 @code{.func} emits debugging information to denote function @var{name}, and
4085 is ignored unless the file is assembled with debugging enabled.
4086 Only @samp{--gstabs} is currently supported.
4087 @var{label} is the entry point of the function and if omitted @var{name}
4088 prepended with the @samp{leading char} is used.
4089 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4090 All functions are currently defined to have @code{void} return type.
4091 The function must be terminated with @code{.endfunc}.
4094 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4096 @cindex @code{global} directive
4097 @cindex symbol, making visible to linker
4098 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4099 @var{symbol} in your partial program, its value is made available to
4100 other partial programs that are linked with it. Otherwise,
4101 @var{symbol} takes its attributes from a symbol of the same name
4102 from another file linked into the same program.
4104 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4105 compatibility with other assemblers.
4108 On the HPPA, @code{.global} is not always enough to make it accessible to other
4109 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4110 @xref{HPPA Directives,, HPPA Assembler Directives}.
4115 @section @code{.hidden @var{names}}
4117 @cindex @code{.hidden} directive
4119 This one of the ELF visibility directives. The other two are
4120 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4121 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4123 This directive overrides the named symbols default visibility (which is set by
4124 their binding: local, global or weak). The directive sets the visibility to
4125 @code{hidden} which means that the symbols are not visible to other components.
4126 Such symbols are always considered to be @code{protected} as well.
4130 @section @code{.hword @var{expressions}}
4132 @cindex @code{hword} directive
4133 @cindex integers, 16-bit
4134 @cindex numbers, 16-bit
4135 @cindex sixteen bit integers
4136 This expects zero or more @var{expressions}, and emits
4137 a 16 bit number for each.
4140 This directive is a synonym for @samp{.short}; depending on the target
4141 architecture, it may also be a synonym for @samp{.word}.
4145 This directive is a synonym for @samp{.short}.
4148 This directive is a synonym for both @samp{.short} and @samp{.word}.
4153 @section @code{.ident}
4155 @cindex @code{ident} directive
4156 This directive is used by some assemblers to place tags in object files.
4157 @command{@value{AS}} simply accepts the directive for source-file
4158 compatibility with such assemblers, but does not actually emit anything
4162 @section @code{.if @var{absolute expression}}
4164 @cindex conditional assembly
4165 @cindex @code{if} directive
4166 @code{.if} marks the beginning of a section of code which is only
4167 considered part of the source program being assembled if the argument
4168 (which must be an @var{absolute expression}) is non-zero. The end of
4169 the conditional section of code must be marked by @code{.endif}
4170 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4171 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4172 If you have several conditions to check, @code{.elseif} may be used to avoid
4173 nesting blocks if/else within each subsequent @code{.else} block.
4175 The following variants of @code{.if} are also supported:
4177 @cindex @code{ifdef} directive
4178 @item .ifdef @var{symbol}
4179 Assembles the following section of code if the specified @var{symbol}
4182 @cindex @code{ifc} directive
4183 @item .ifc @var{string1},@var{string2}
4184 Assembles the following section of code if the two strings are the same. The
4185 strings may be optionally quoted with single quotes. If they are not quoted,
4186 the first string stops at the first comma, and the second string stops at the
4187 end of the line. Strings which contain whitespace should be quoted. The
4188 string comparison is case sensitive.
4190 @cindex @code{ifeq} directive
4191 @item .ifeq @var{absolute expression}
4192 Assembles the following section of code if the argument is zero.
4194 @cindex @code{ifeqs} directive
4195 @item .ifeqs @var{string1},@var{string2}
4196 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4198 @cindex @code{ifge} directive
4199 @item .ifge @var{absolute expression}
4200 Assembles the following section of code if the argument is greater than or
4203 @cindex @code{ifgt} directive
4204 @item .ifgt @var{absolute expression}
4205 Assembles the following section of code if the argument is greater than zero.
4207 @cindex @code{ifle} directive
4208 @item .ifle @var{absolute expression}
4209 Assembles the following section of code if the argument is less than or equal
4212 @cindex @code{iflt} directive
4213 @item .iflt @var{absolute expression}
4214 Assembles the following section of code if the argument is less than zero.
4216 @cindex @code{ifnc} directive
4217 @item .ifnc @var{string1},@var{string2}.
4218 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4219 following section of code if the two strings are not the same.
4221 @cindex @code{ifndef} directive
4222 @cindex @code{ifnotdef} directive
4223 @item .ifndef @var{symbol}
4224 @itemx .ifnotdef @var{symbol}
4225 Assembles the following section of code if the specified @var{symbol}
4226 has not been defined. Both spelling variants are equivalent.
4228 @cindex @code{ifne} directive
4229 @item .ifne @var{absolute expression}
4230 Assembles the following section of code if the argument is not equal to zero
4231 (in other words, this is equivalent to @code{.if}).
4233 @cindex @code{ifnes} directive
4234 @item .ifnes @var{string1},@var{string2}
4235 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4236 following section of code if the two strings are not the same.
4240 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4242 @cindex @code{incbin} directive
4243 @cindex binary files, including
4244 The @code{incbin} directive includes @var{file} verbatim at the current
4245 location. You can control the search paths used with the @samp{-I} command-line
4246 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4249 The @var{skip} argument skips a number of bytes from the start of the
4250 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4251 read. Note that the data is not aligned in any way, so it is the user's
4252 responsibility to make sure that proper alignment is provided both before and
4253 after the @code{incbin} directive.
4256 @section @code{.include "@var{file}"}
4258 @cindex @code{include} directive
4259 @cindex supporting files, including
4260 @cindex files, including
4261 This directive provides a way to include supporting files at specified
4262 points in your source program. The code from @var{file} is assembled as
4263 if it followed the point of the @code{.include}; when the end of the
4264 included file is reached, assembly of the original file continues. You
4265 can control the search paths used with the @samp{-I} command-line option
4266 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4270 @section @code{.int @var{expressions}}
4272 @cindex @code{int} directive
4273 @cindex integers, 32-bit
4274 Expect zero or more @var{expressions}, of any section, separated by commas.
4275 For each expression, emit a number that, at run time, is the value of that
4276 expression. The byte order and bit size of the number depends on what kind
4277 of target the assembly is for.
4281 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4282 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4289 @section @code{.internal @var{names}}
4291 @cindex @code{.internal} directive
4293 This one of the ELF visibility directives. The other two are
4294 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4295 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4297 This directive overrides the named symbols default visibility (which is set by
4298 their binding: local, global or weak). The directive sets the visibility to
4299 @code{internal} which means that the symbols are considered to be @code{hidden}
4300 (ie not visible to other components), and that some extra, processor specific
4301 processing must also be performed upon the symbols as well.
4305 @section @code{.irp @var{symbol},@var{values}}@dots{}
4307 @cindex @code{irp} directive
4308 Evaluate a sequence of statements assigning different values to @var{symbol}.
4309 The sequence of statements starts at the @code{.irp} directive, and is
4310 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4311 set to @var{value}, and the sequence of statements is assembled. If no
4312 @var{value} is listed, the sequence of statements is assembled once, with
4313 @var{symbol} set to the null string. To refer to @var{symbol} within the
4314 sequence of statements, use @var{\symbol}.
4316 For example, assembling
4324 is equivalent to assembling
4333 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4335 @cindex @code{irpc} directive
4336 Evaluate a sequence of statements assigning different values to @var{symbol}.
4337 The sequence of statements starts at the @code{.irpc} directive, and is
4338 terminated by an @code{.endr} directive. For each character in @var{value},
4339 @var{symbol} is set to the character, and the sequence of statements is
4340 assembled. If no @var{value} is listed, the sequence of statements is
4341 assembled once, with @var{symbol} set to the null string. To refer to
4342 @var{symbol} within the sequence of statements, use @var{\symbol}.
4344 For example, assembling
4352 is equivalent to assembling
4361 @section @code{.lcomm @var{symbol} , @var{length}}
4363 @cindex @code{lcomm} directive
4364 @cindex local common symbols
4365 @cindex symbols, local common
4366 Reserve @var{length} (an absolute expression) bytes for a local common
4367 denoted by @var{symbol}. The section and value of @var{symbol} are
4368 those of the new local common. The addresses are allocated in the bss
4369 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4370 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4371 not visible to @code{@value{LD}}.
4374 Some targets permit a third argument to be used with @code{.lcomm}. This
4375 argument specifies the desired alignment of the symbol in the bss section.
4379 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4380 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4384 @section @code{.lflags}
4386 @cindex @code{lflags} directive (ignored)
4387 @command{@value{AS}} accepts this directive, for compatibility with other
4388 assemblers, but ignores it.
4390 @ifclear no-line-dir
4392 @section @code{.line @var{line-number}}
4394 @cindex @code{line} directive
4398 @section @code{.ln @var{line-number}}
4400 @cindex @code{ln} directive
4402 @cindex logical line number
4404 Change the logical line number. @var{line-number} must be an absolute
4405 expression. The next line has that logical line number. Therefore any other
4406 statements on the current line (after a statement separator character) are
4407 reported as on logical line number @var{line-number} @minus{} 1. One day
4408 @command{@value{AS}} will no longer support this directive: it is recognized only
4409 for compatibility with existing assembler programs.
4413 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4414 not available; use the synonym @code{.ln} in that context.
4419 @ifclear no-line-dir
4420 Even though this is a directive associated with the @code{a.out} or
4421 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4422 when producing COFF output, and treats @samp{.line} as though it
4423 were the COFF @samp{.ln} @emph{if} it is found outside a
4424 @code{.def}/@code{.endef} pair.
4426 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4427 used by compilers to generate auxiliary symbol information for
4432 @section @code{.linkonce [@var{type}]}
4434 @cindex @code{linkonce} directive
4435 @cindex common sections
4436 Mark the current section so that the linker only includes a single copy of it.
4437 This may be used to include the same section in several different object files,
4438 but ensure that the linker will only include it once in the final output file.
4439 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4440 Duplicate sections are detected based on the section name, so it should be
4443 This directive is only supported by a few object file formats; as of this
4444 writing, the only object file format which supports it is the Portable
4445 Executable format used on Windows NT.
4447 The @var{type} argument is optional. If specified, it must be one of the
4448 following strings. For example:
4452 Not all types may be supported on all object file formats.
4456 Silently discard duplicate sections. This is the default.
4459 Warn if there are duplicate sections, but still keep only one copy.
4462 Warn if any of the duplicates have different sizes.
4465 Warn if any of the duplicates do not have exactly the same contents.
4469 @section @code{.ln @var{line-number}}
4471 @cindex @code{ln} directive
4472 @ifclear no-line-dir
4473 @samp{.ln} is a synonym for @samp{.line}.
4476 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4477 must be an absolute expression. The next line has that logical
4478 line number, so any other statements on the current line (after a
4479 statement separator character @code{;}) are reported as on logical
4480 line number @var{line-number} @minus{} 1.
4483 This directive is accepted, but ignored, when @command{@value{AS}} is
4484 configured for @code{b.out}; its effect is only associated with COFF
4490 @section @code{.mri @var{val}}
4492 @cindex @code{mri} directive
4493 @cindex MRI mode, temporarily
4494 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4495 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4496 affects code assembled until the next @code{.mri} directive, or until the end
4497 of the file. @xref{M, MRI mode, MRI mode}.
4500 @section @code{.list}
4502 @cindex @code{list} directive
4503 @cindex listing control, turning on
4504 Control (in conjunction with the @code{.nolist} directive) whether or
4505 not assembly listings are generated. These two directives maintain an
4506 internal counter (which is zero initially). @code{.list} increments the
4507 counter, and @code{.nolist} decrements it. Assembly listings are
4508 generated whenever the counter is greater than zero.
4510 By default, listings are disabled. When you enable them (with the
4511 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4512 the initial value of the listing counter is one.
4515 @section @code{.long @var{expressions}}
4517 @cindex @code{long} directive
4518 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4521 @c no one seems to know what this is for or whether this description is
4522 @c what it really ought to do
4524 @section @code{.lsym @var{symbol}, @var{expression}}
4526 @cindex @code{lsym} directive
4527 @cindex symbol, not referenced in assembly
4528 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4529 the hash table, ensuring it cannot be referenced by name during the
4530 rest of the assembly. This sets the attributes of the symbol to be
4531 the same as the expression value:
4533 @var{other} = @var{descriptor} = 0
4534 @var{type} = @r{(section of @var{expression})}
4535 @var{value} = @var{expression}
4538 The new symbol is not flagged as external.
4542 @section @code{.macro}
4545 The commands @code{.macro} and @code{.endm} allow you to define macros that
4546 generate assembly output. For example, this definition specifies a macro
4547 @code{sum} that puts a sequence of numbers into memory:
4550 .macro sum from=0, to=5
4559 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4571 @item .macro @var{macname}
4572 @itemx .macro @var{macname} @var{macargs} @dots{}
4573 @cindex @code{macro} directive
4574 Begin the definition of a macro called @var{macname}. If your macro
4575 definition requires arguments, specify their names after the macro name,
4576 separated by commas or spaces. You can supply a default value for any
4577 macro argument by following the name with @samp{=@var{deflt}}. For
4578 example, these are all valid @code{.macro} statements:
4582 Begin the definition of a macro called @code{comm}, which takes no
4585 @item .macro plus1 p, p1
4586 @itemx .macro plus1 p p1
4587 Either statement begins the definition of a macro called @code{plus1},
4588 which takes two arguments; within the macro definition, write
4589 @samp{\p} or @samp{\p1} to evaluate the arguments.
4591 @item .macro reserve_str p1=0 p2
4592 Begin the definition of a macro called @code{reserve_str}, with two
4593 arguments. The first argument has a default value, but not the second.
4594 After the definition is complete, you can call the macro either as
4595 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4596 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4597 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4598 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4601 When you call a macro, you can specify the argument values either by
4602 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4603 @samp{sum to=17, from=9}.
4606 @cindex @code{endm} directive
4607 Mark the end of a macro definition.
4610 @cindex @code{exitm} directive
4611 Exit early from the current macro definition.
4613 @cindex number of macros executed
4614 @cindex macros, count executed
4616 @command{@value{AS}} maintains a counter of how many macros it has
4617 executed in this pseudo-variable; you can copy that number to your
4618 output with @samp{\@@}, but @emph{only within a macro definition}.
4621 @item LOCAL @var{name} [ , @dots{} ]
4622 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4623 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4624 Alternate macro syntax}.
4626 Generate a string replacement for each of the @var{name} arguments, and
4627 replace any instances of @var{name} in each macro expansion. The
4628 replacement string is unique in the assembly, and different for each
4629 separate macro expansion. @code{LOCAL} allows you to write macros that
4630 define symbols, without fear of conflict between separate macro expansions.
4635 @section @code{.nolist}
4637 @cindex @code{nolist} directive
4638 @cindex listing control, turning off
4639 Control (in conjunction with the @code{.list} directive) whether or
4640 not assembly listings are generated. These two directives maintain an
4641 internal counter (which is zero initially). @code{.list} increments the
4642 counter, and @code{.nolist} decrements it. Assembly listings are
4643 generated whenever the counter is greater than zero.
4646 @section @code{.octa @var{bignums}}
4648 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4649 @cindex @code{octa} directive
4650 @cindex integer, 16-byte
4651 @cindex sixteen byte integer
4652 This directive expects zero or more bignums, separated by commas. For each
4653 bignum, it emits a 16-byte integer.
4655 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4656 hence @emph{octa}-word for 16 bytes.
4659 @section @code{.org @var{new-lc} , @var{fill}}
4661 @cindex @code{org} directive
4662 @cindex location counter, advancing
4663 @cindex advancing location counter
4664 @cindex current address, advancing
4665 Advance the location counter of the current section to
4666 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4667 expression with the same section as the current subsection. That is,
4668 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4669 wrong section, the @code{.org} directive is ignored. To be compatible
4670 with former assemblers, if the section of @var{new-lc} is absolute,
4671 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4672 is the same as the current subsection.
4674 @code{.org} may only increase the location counter, or leave it
4675 unchanged; you cannot use @code{.org} to move the location counter
4678 @c double negative used below "not undefined" because this is a specific
4679 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4680 @c section. doc@cygnus.com 18feb91
4681 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4682 may not be undefined. If you really detest this restriction we eagerly await
4683 a chance to share your improved assembler.
4685 Beware that the origin is relative to the start of the section, not
4686 to the start of the subsection. This is compatible with other
4687 people's assemblers.
4689 When the location counter (of the current subsection) is advanced, the
4690 intervening bytes are filled with @var{fill} which should be an
4691 absolute expression. If the comma and @var{fill} are omitted,
4692 @var{fill} defaults to zero.
4695 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4697 @cindex padding the location counter given a power of two
4698 @cindex @code{p2align} directive
4699 Pad the location counter (in the current subsection) to a particular
4700 storage boundary. The first expression (which must be absolute) is the
4701 number of low-order zero bits the location counter must have after
4702 advancement. For example @samp{.p2align 3} advances the location
4703 counter until it a multiple of 8. If the location counter is already a
4704 multiple of 8, no change is needed.
4706 The second expression (also absolute) gives the fill value to be stored in the
4707 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4708 padding bytes are normally zero. However, on some systems, if the section is
4709 marked as containing code and the fill value is omitted, the space is filled
4710 with no-op instructions.
4712 The third expression is also absolute, and is also optional. If it is present,
4713 it is the maximum number of bytes that should be skipped by this alignment
4714 directive. If doing the alignment would require skipping more bytes than the
4715 specified maximum, then the alignment is not done at all. You can omit the
4716 fill value (the second argument) entirely by simply using two commas after the
4717 required alignment; this can be useful if you want the alignment to be filled
4718 with no-op instructions when appropriate.
4720 @cindex @code{p2alignw} directive
4721 @cindex @code{p2alignl} directive
4722 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4723 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4724 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4725 fill pattern as a four byte longword value. For example, @code{.p2alignw
4726 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4727 filled in with the value 0x368d (the exact placement of the bytes depends upon
4728 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4733 @section @code{.previous}
4735 @cindex @code{.previous} directive
4736 @cindex Section Stack
4737 This is one of the ELF section stack manipulation directives. The others are
4738 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4739 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4740 (@pxref{PopSection}).
4742 This directive swaps the current section (and subsection) with most recently
4743 referenced section (and subsection) prior to this one. Multiple
4744 @code{.previous} directives in a row will flip between two sections (and their
4747 In terms of the section stack, this directive swaps the current section with
4748 the top section on the section stack.
4753 @section @code{.popsection}
4755 @cindex @code{.popsection} directive
4756 @cindex Section Stack
4757 This is one of the ELF section stack manipulation directives. The others are
4758 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4759 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4762 This directive replaces the current section (and subsection) with the top
4763 section (and subsection) on the section stack. This section is popped off the
4768 @section @code{.print @var{string}}
4770 @cindex @code{print} directive
4771 @command{@value{AS}} will print @var{string} on the standard output during
4772 assembly. You must put @var{string} in double quotes.
4776 @section @code{.protected @var{names}}
4778 @cindex @code{.protected} directive
4780 This one of the ELF visibility directives. The other two are
4781 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4783 This directive overrides the named symbols default visibility (which is set by
4784 their binding: local, global or weak). The directive sets the visibility to
4785 @code{protected} which means that any references to the symbols from within the
4786 components that defines them must be resolved to the definition in that
4787 component, even if a definition in another component would normally preempt
4792 @section @code{.psize @var{lines} , @var{columns}}
4794 @cindex @code{psize} directive
4795 @cindex listing control: paper size
4796 @cindex paper size, for listings
4797 Use this directive to declare the number of lines---and, optionally, the
4798 number of columns---to use for each page, when generating listings.
4800 If you do not use @code{.psize}, listings use a default line-count
4801 of 60. You may omit the comma and @var{columns} specification; the
4802 default width is 200 columns.
4804 @command{@value{AS}} generates formfeeds whenever the specified number of
4805 lines is exceeded (or whenever you explicitly request one, using
4808 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4809 those explicitly specified with @code{.eject}.
4812 @section @code{.purgem @var{name}}
4814 @cindex @code{purgem} directive
4815 Undefine the macro @var{name}, so that later uses of the string will not be
4816 expanded. @xref{Macro}.
4820 @section @code{.pushsection @var{name} , @var{subsection}}
4822 @cindex @code{.pushsection} directive
4823 @cindex Section Stack
4824 This is one of the ELF section stack manipulation directives. The others are
4825 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4826 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4829 This directive is a synonym for @code{.section}. It pushes the current section
4830 (and subsection) onto the top of the section stack, and then replaces the
4831 current section and subsection with @code{name} and @code{subsection}.
4835 @section @code{.quad @var{bignums}}
4837 @cindex @code{quad} directive
4838 @code{.quad} expects zero or more bignums, separated by commas. For
4839 each bignum, it emits
4841 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4842 warning message; and just takes the lowest order 8 bytes of the bignum.
4843 @cindex eight-byte integer
4844 @cindex integer, 8-byte
4846 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4847 hence @emph{quad}-word for 8 bytes.
4850 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4851 warning message; and just takes the lowest order 16 bytes of the bignum.
4852 @cindex sixteen-byte integer
4853 @cindex integer, 16-byte
4857 @section @code{.rept @var{count}}
4859 @cindex @code{rept} directive
4860 Repeat the sequence of lines between the @code{.rept} directive and the next
4861 @code{.endr} directive @var{count} times.
4863 For example, assembling
4871 is equivalent to assembling
4880 @section @code{.sbttl "@var{subheading}"}
4882 @cindex @code{sbttl} directive
4883 @cindex subtitles for listings
4884 @cindex listing control: subtitle
4885 Use @var{subheading} as the title (third line, immediately after the
4886 title line) when generating assembly listings.
4888 This directive affects subsequent pages, as well as the current page if
4889 it appears within ten lines of the top of a page.
4893 @section @code{.scl @var{class}}
4895 @cindex @code{scl} directive
4896 @cindex symbol storage class (COFF)
4897 @cindex COFF symbol storage class
4898 Set the storage-class value for a symbol. This directive may only be
4899 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4900 whether a symbol is static or external, or it may record further
4901 symbolic debugging information.
4904 The @samp{.scl} directive is primarily associated with COFF output; when
4905 configured to generate @code{b.out} output format, @command{@value{AS}}
4906 accepts this directive but ignores it.
4911 @section @code{.section @var{name}} (COFF version)
4913 @cindex @code{section} directive
4914 @cindex named section
4915 Use the @code{.section} directive to assemble the following code into a section
4918 This directive is only supported for targets that actually support arbitrarily
4919 named sections; on @code{a.out} targets, for example, it is not accepted, even
4920 with a standard @code{a.out} section name.
4922 For COFF targets, the @code{.section} directive is used in one of the following
4926 .section @var{name}[, "@var{flags}"]
4927 .section @var{name}[, @var{subsegment}]
4930 If the optional argument is quoted, it is taken as flags to use for the
4931 section. Each flag is a single character. The following flags are recognized:
4934 bss section (uninitialized data)
4936 section is not loaded
4946 shared section (meaningful for PE targets)
4949 If no flags are specified, the default flags depend upon the section name. If
4950 the section name is not recognized, the default will be for the section to be
4951 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4952 from the section, rather than adding them, so if they are used on their own it
4953 will be as if no flags had been specified at all.
4955 If the optional argument to the @code{.section} directive is not quoted, it is
4956 taken as a subsegment number (@pxref{Sub-Sections}).
4959 @section @code{.section @var{name}} (ELF version)
4961 @cindex @code{section} directive
4962 @cindex named section
4964 @cindex Section Stack
4965 This is one of the ELF section stack manipulation directives. The others are
4966 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4967 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4968 @code{.previous} (@pxref{Previous}).
4971 For ELF targets, the @code{.section} directive is used like this:
4974 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
4977 The optional @var{flags} argument is a quoted string which may contain any
4978 combination of the following characters:
4981 section is allocatable
4985 section is executable
4987 section is mergeable
4989 section contains zero terminated strings
4992 The optional @var{type} argument may contain one of the following constants:
4995 section contains data
4997 section does not contain data (i.e., section only occupies space)
5000 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5001 as well as @var{entsize} argument. Sections with @code{M} flag but not
5002 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5003 long. Sections with both @code{M} and @code{S} must contain zero terminated
5004 strings where each character is @var{entsize} bytes long. The linker may remove
5005 duplicates within sections with the same name, same entity size and same flags.
5007 If no flags are specified, the default flags depend upon the section name. If
5008 the section name is not recognized, the default will be for the section to have
5009 none of the above flags: it will not be allocated in memory, nor writable, nor
5010 executable. The section will contain data.
5012 For ELF targets, the assembler supports another type of @code{.section}
5013 directive for compatibility with the Solaris assembler:
5016 .section "@var{name}"[, @var{flags}...]
5019 Note that the section name is quoted. There may be a sequence of comma
5023 section is allocatable
5027 section is executable
5030 This directive replaces the current section and subsection. The replaced
5031 section and subsection are pushed onto the section stack. See the contents of
5032 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5033 how this directive and the other section stack directives work.
5036 @section @code{.set @var{symbol}, @var{expression}}
5038 @cindex @code{set} directive
5039 @cindex symbol value, setting
5040 Set the value of @var{symbol} to @var{expression}. This
5041 changes @var{symbol}'s value and type to conform to
5042 @var{expression}. If @var{symbol} was flagged as external, it remains
5043 flagged (@pxref{Symbol Attributes}).
5045 You may @code{.set} a symbol many times in the same assembly.
5047 If you @code{.set} a global symbol, the value stored in the object
5048 file is the last value stored into it.
5051 The syntax for @code{set} on the HPPA is
5052 @samp{@var{symbol} .set @var{expression}}.
5056 @section @code{.short @var{expressions}}
5058 @cindex @code{short} directive
5060 @code{.short} is normally the same as @samp{.word}.
5061 @xref{Word,,@code{.word}}.
5063 In some configurations, however, @code{.short} and @code{.word} generate
5064 numbers of different lengths; @pxref{Machine Dependencies}.
5068 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5071 This expects zero or more @var{expressions}, and emits
5072 a 16 bit number for each.
5077 @section @code{.single @var{flonums}}
5079 @cindex @code{single} directive
5080 @cindex floating point numbers (single)
5081 This directive assembles zero or more flonums, separated by commas. It
5082 has the same effect as @code{.float}.
5084 The exact kind of floating point numbers emitted depends on how
5085 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5089 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5090 numbers in @sc{ieee} format.
5095 @section @code{.size} (COFF version)
5097 @cindex @code{size} directive
5098 This directive is generated by compilers to include auxiliary debugging
5099 information in the symbol table. It is only permitted inside
5100 @code{.def}/@code{.endef} pairs.
5103 @samp{.size} is only meaningful when generating COFF format output; when
5104 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5108 @section @code{.size @var{name} , @var{expression}} (ELF version)
5109 @cindex @code{size} directive
5111 This directive is used to set the size associated with a symbol @var{name}.
5112 The size in bytes is computed from @var{expression} which can make use of label
5113 arithmetic. This directive is typically used to set the size of function
5117 @section @code{.sleb128 @var{expressions}}
5119 @cindex @code{sleb128} directive
5120 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5121 compact, variable length representation of numbers used by the DWARF
5122 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5124 @ifclear no-space-dir
5126 @section @code{.skip @var{size} , @var{fill}}
5128 @cindex @code{skip} directive
5129 @cindex filling memory
5130 This directive emits @var{size} bytes, each of value @var{fill}. Both
5131 @var{size} and @var{fill} are absolute expressions. If the comma and
5132 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5136 @section @code{.space @var{size} , @var{fill}}
5138 @cindex @code{space} directive
5139 @cindex filling memory
5140 This directive emits @var{size} bytes, each of value @var{fill}. Both
5141 @var{size} and @var{fill} are absolute expressions. If the comma
5142 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5147 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5148 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5149 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5150 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5159 @section @code{.space}
5160 @cindex @code{space} directive
5162 On the AMD 29K, this directive is ignored; it is accepted for
5163 compatibility with other AMD 29K assemblers.
5166 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5167 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5173 @section @code{.stabd, .stabn, .stabs}
5175 @cindex symbolic debuggers, information for
5176 @cindex @code{stab@var{x}} directives
5177 There are three directives that begin @samp{.stab}.
5178 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5179 The symbols are not entered in the @command{@value{AS}} hash table: they
5180 cannot be referenced elsewhere in the source file.
5181 Up to five fields are required:
5185 This is the symbol's name. It may contain any character except
5186 @samp{\000}, so is more general than ordinary symbol names. Some
5187 debuggers used to code arbitrarily complex structures into symbol names
5191 An absolute expression. The symbol's type is set to the low 8 bits of
5192 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5193 and debuggers choke on silly bit patterns.
5196 An absolute expression. The symbol's ``other'' attribute is set to the
5197 low 8 bits of this expression.
5200 An absolute expression. The symbol's descriptor is set to the low 16
5201 bits of this expression.
5204 An absolute expression which becomes the symbol's value.
5207 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5208 or @code{.stabs} statement, the symbol has probably already been created;
5209 you get a half-formed symbol in your object file. This is
5210 compatible with earlier assemblers!
5213 @cindex @code{stabd} directive
5214 @item .stabd @var{type} , @var{other} , @var{desc}
5216 The ``name'' of the symbol generated is not even an empty string.
5217 It is a null pointer, for compatibility. Older assemblers used a
5218 null pointer so they didn't waste space in object files with empty
5221 The symbol's value is set to the location counter,
5222 relocatably. When your program is linked, the value of this symbol
5223 is the address of the location counter when the @code{.stabd} was
5226 @cindex @code{stabn} directive
5227 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5228 The name of the symbol is set to the empty string @code{""}.
5230 @cindex @code{stabs} directive
5231 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5232 All five fields are specified.
5238 @section @code{.string} "@var{str}"
5240 @cindex string, copying to object file
5241 @cindex @code{string} directive
5243 Copy the characters in @var{str} to the object file. You may specify more than
5244 one string to copy, separated by commas. Unless otherwise specified for a
5245 particular machine, the assembler marks the end of each string with a 0 byte.
5246 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5249 @section @code{.struct @var{expression}}
5251 @cindex @code{struct} directive
5252 Switch to the absolute section, and set the section offset to @var{expression},
5253 which must be an absolute expression. You might use this as follows:
5262 This would define the symbol @code{field1} to have the value 0, the symbol
5263 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5264 value 8. Assembly would be left in the absolute section, and you would need to
5265 use a @code{.section} directive of some sort to change to some other section
5266 before further assembly.
5270 @section @code{.subsection @var{name}}
5272 @cindex @code{.subsection} directive
5273 @cindex Section Stack
5274 This is one of the ELF section stack manipulation directives. The others are
5275 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5276 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5279 This directive replaces the current subsection with @code{name}. The current
5280 section is not changed. The replaced subsection is put onto the section stack
5281 in place of the then current top of stack subsection.
5286 @section @code{.symver}
5287 @cindex @code{symver} directive
5288 @cindex symbol versioning
5289 @cindex versions of symbols
5290 Use the @code{.symver} directive to bind symbols to specific version nodes
5291 within a source file. This is only supported on ELF platforms, and is
5292 typically used when assembling files to be linked into a shared library.
5293 There are cases where it may make sense to use this in objects to be bound
5294 into an application itself so as to override a versioned symbol from a
5297 For ELF targets, the @code{.symver} directive can be used like this:
5299 .symver @var{name}, @var{name2@@nodename}
5301 If the symbol @var{name} is defined within the file
5302 being assembled, the @code{.symver} directive effectively creates a symbol
5303 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5304 just don't try and create a regular alias is that the @var{@@} character isn't
5305 permitted in symbol names. The @var{name2} part of the name is the actual name
5306 of the symbol by which it will be externally referenced. The name @var{name}
5307 itself is merely a name of convenience that is used so that it is possible to
5308 have definitions for multiple versions of a function within a single source
5309 file, and so that the compiler can unambiguously know which version of a
5310 function is being mentioned. The @var{nodename} portion of the alias should be
5311 the name of a node specified in the version script supplied to the linker when
5312 building a shared library. If you are attempting to override a versioned
5313 symbol from a shared library, then @var{nodename} should correspond to the
5314 nodename of the symbol you are trying to override.
5316 If the symbol @var{name} is not defined within the file being assembled, all
5317 references to @var{name} will be changed to @var{name2@@nodename}. If no
5318 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5321 Another usage of the @code{.symver} directive is:
5323 .symver @var{name}, @var{name2@@@@nodename}
5325 In this case, the symbol @var{name} must exist and be defined within
5326 the file being assembled. It is similar to @var{name2@@nodename}. The
5327 difference is @var{name2@@@@nodename} will also be used to resolve
5328 references to @var{name2} by the linker.
5330 The third usage of the @code{.symver} directive is:
5332 .symver @var{name}, @var{name2@@@@@@nodename}
5334 When @var{name} is not defined within the
5335 file being assembled, it is treated as @var{name2@@nodename}. When
5336 @var{name} is defined within the file being assembled, the symbol
5337 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5342 @section @code{.tag @var{structname}}
5344 @cindex COFF structure debugging
5345 @cindex structure debugging, COFF
5346 @cindex @code{tag} directive
5347 This directive is generated by compilers to include auxiliary debugging
5348 information in the symbol table. It is only permitted inside
5349 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5350 definitions in the symbol table with instances of those structures.
5353 @samp{.tag} is only used when generating COFF format output; when
5354 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5360 @section @code{.text @var{subsection}}
5362 @cindex @code{text} directive
5363 Tells @command{@value{AS}} to assemble the following statements onto the end of
5364 the text subsection numbered @var{subsection}, which is an absolute
5365 expression. If @var{subsection} is omitted, subsection number zero
5369 @section @code{.title "@var{heading}"}
5371 @cindex @code{title} directive
5372 @cindex listing control: title line
5373 Use @var{heading} as the title (second line, immediately after the
5374 source file name and pagenumber) when generating assembly listings.
5376 This directive affects subsequent pages, as well as the current page if
5377 it appears within ten lines of the top of a page.
5380 @section @code{.type @var{int}} (COFF version)
5382 @cindex COFF symbol type
5383 @cindex symbol type, COFF
5384 @cindex @code{type} directive
5385 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5386 records the integer @var{int} as the type attribute of a symbol table entry.
5389 @samp{.type} is associated only with COFF format output; when
5390 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5391 directive but ignores it.
5394 @section @code{.type @var{name} , @var{type description}} (ELF version)
5396 @cindex ELF symbol type
5397 @cindex symbol type, ELF
5398 @cindex @code{type} directive
5399 This directive is used to set the type of symbol @var{name} to be either a
5400 function symbol or an object symbol. There are five different syntaxes
5401 supported for the @var{type description} field, in order to provide
5402 compatibility with various other assemblers. The syntaxes supported are:
5405 .type <name>,#function
5406 .type <name>,#object
5408 .type <name>,@@function
5409 .type <name>,@@object
5411 .type <name>,%function
5412 .type <name>,%object
5414 .type <name>,"function"
5415 .type <name>,"object"
5417 .type <name> STT_FUNCTION
5418 .type <name> STT_OBJECT
5422 @section @code{.uleb128 @var{expressions}}
5424 @cindex @code{uleb128} directive
5425 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5426 compact, variable length representation of numbers used by the DWARF
5427 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5431 @section @code{.val @var{addr}}
5433 @cindex @code{val} directive
5434 @cindex COFF value attribute
5435 @cindex value attribute, COFF
5436 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5437 records the address @var{addr} as the value attribute of a symbol table
5441 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5442 configured for @code{b.out}, it accepts this directive but ignores it.
5448 @section @code{.version "@var{string}"}
5450 @cindex @code{.version}
5451 This directive creates a @code{.note} section and places into it an ELF
5452 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5457 @section @code{.vtable_entry @var{table}, @var{offset}}
5459 @cindex @code{.vtable_entry}
5460 This directive finds or creates a symbol @code{table} and creates a
5461 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5464 @section @code{.vtable_inherit @var{child}, @var{parent}}
5466 @cindex @code{.vtable_inherit}
5467 This directive finds the symbol @code{child} and finds or creates the symbol
5468 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5469 parent whose addend is the value of the child symbol. As a special case the
5470 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5475 @section @code{.weak @var{names}}
5477 @cindex @code{.weak}
5478 This directive sets the weak attribute on the comma separated list of symbol
5479 @code{names}. If the symbols do not already exist, they will be created.
5483 @section @code{.word @var{expressions}}
5485 @cindex @code{word} directive
5486 This directive expects zero or more @var{expressions}, of any section,
5487 separated by commas.
5490 For each expression, @command{@value{AS}} emits a 32-bit number.
5493 For each expression, @command{@value{AS}} emits a 16-bit number.
5498 The size of the number emitted, and its byte order,
5499 depend on what target computer the assembly is for.
5502 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5503 @c happen---32-bit addressability, period; no long/short jumps.
5504 @ifset DIFF-TBL-KLUGE
5505 @cindex difference tables altered
5506 @cindex altered difference tables
5508 @emph{Warning: Special Treatment to support Compilers}
5512 Machines with a 32-bit address space, but that do less than 32-bit
5513 addressing, require the following special treatment. If the machine of
5514 interest to you does 32-bit addressing (or doesn't require it;
5515 @pxref{Machine Dependencies}), you can ignore this issue.
5518 In order to assemble compiler output into something that works,
5519 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5520 Directives of the form @samp{.word sym1-sym2} are often emitted by
5521 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5522 directive of the form @samp{.word sym1-sym2}, and the difference between
5523 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5524 creates a @dfn{secondary jump table}, immediately before the next label.
5525 This secondary jump table is preceded by a short-jump to the
5526 first byte after the secondary table. This short-jump prevents the flow
5527 of control from accidentally falling into the new table. Inside the
5528 table is a long-jump to @code{sym2}. The original @samp{.word}
5529 contains @code{sym1} minus the address of the long-jump to
5532 If there were several occurrences of @samp{.word sym1-sym2} before the
5533 secondary jump table, all of them are adjusted. If there was a
5534 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5535 long-jump to @code{sym4} is included in the secondary jump table,
5536 and the @code{.word} directives are adjusted to contain @code{sym3}
5537 minus the address of the long-jump to @code{sym4}; and so on, for as many
5538 entries in the original jump table as necessary.
5541 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5542 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5543 assembly language programmers.
5546 @c end DIFF-TBL-KLUGE
5549 @section Deprecated Directives
5551 @cindex deprecated directives
5552 @cindex obsolescent directives
5553 One day these directives won't work.
5554 They are included for compatibility with older assemblers.
5561 @node Machine Dependencies
5562 @chapter Machine Dependent Features
5564 @cindex machine dependencies
5565 The machine instruction sets are (almost by definition) different on
5566 each machine where @command{@value{AS}} runs. Floating point representations
5567 vary as well, and @command{@value{AS}} often supports a few additional
5568 directives or command-line options for compatibility with other
5569 assemblers on a particular platform. Finally, some versions of
5570 @command{@value{AS}} support special pseudo-instructions for branch
5573 This chapter discusses most of these differences, though it does not
5574 include details on any machine's instruction set. For details on that
5575 subject, see the hardware manufacturer's manual.
5579 * AMD29K-Dependent:: AMD 29K Dependent Features
5582 * ARC-Dependent:: ARC Dependent Features
5585 * ARM-Dependent:: ARM Dependent Features
5588 * D10V-Dependent:: D10V Dependent Features
5591 * D30V-Dependent:: D30V Dependent Features
5594 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5597 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5600 * HPPA-Dependent:: HPPA Dependent Features
5603 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5606 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5609 * i860-Dependent:: Intel 80860 Dependent Features
5612 * i960-Dependent:: Intel 80960 Dependent Features
5615 * M32R-Dependent:: M32R Dependent Features
5618 * M68K-Dependent:: M680x0 Dependent Features
5621 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5624 * M88K-Dependent:: M880x0 Dependent Features
5627 * MIPS-Dependent:: MIPS Dependent Features
5630 * MMIX-Dependent:: MMIX Dependent Features
5633 * SH-Dependent:: Hitachi SH Dependent Features
5636 * PDP-11-Dependent:: PDP-11 Dependent Features
5639 * PJ-Dependent:: picoJava Dependent Features
5642 * PPC-Dependent:: PowerPC Dependent Features
5645 * Sparc-Dependent:: SPARC Dependent Features
5648 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5651 * V850-Dependent:: V850 Dependent Features
5654 * Z8000-Dependent:: Z8000 Dependent Features
5657 * Vax-Dependent:: VAX Dependent Features
5664 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5665 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5666 @c peculiarity: to preserve cross-references, there must be a node called
5667 @c "Machine Dependencies". Hence the conditional nodenames in each
5668 @c major node below. Node defaulting in makeinfo requires adjacency of
5669 @c node and sectioning commands; hence the repetition of @chapter BLAH
5670 @c in both conditional blocks.
5677 @include c-a29k.texi
5686 @node Machine Dependencies
5687 @chapter Machine Dependent Features
5689 The machine instruction sets are different on each Hitachi chip family,
5690 and there are also some syntax differences among the families. This
5691 chapter describes the specific @command{@value{AS}} features for each
5695 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5696 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5697 * SH-Dependent:: Hitachi SH Dependent Features
5704 @include c-d10v.texi
5708 @include c-d30v.texi
5712 @include c-h8300.texi
5716 @include c-h8500.texi
5720 @include c-hppa.texi
5724 @include c-i370.texi
5728 @include c-i386.texi
5732 @include c-i860.texi
5736 @include c-i960.texi
5740 @include c-m32r.texi
5744 @include c-m68k.texi
5748 @include c-m68hc11.texi
5752 @include c-m88k.texi
5756 @include c-mips.texi
5760 @include c-mmix.texi
5764 @include c-ns32k.texi
5768 @include c-pdp11.texi
5784 @include c-sparc.texi
5788 @include c-tic54x.texi
5800 @include c-v850.texi
5804 @c reverse effect of @down at top of generic Machine-Dep chapter
5808 @node Reporting Bugs
5809 @chapter Reporting Bugs
5810 @cindex bugs in assembler
5811 @cindex reporting bugs in assembler
5813 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5815 Reporting a bug may help you by bringing a solution to your problem, or it may
5816 not. But in any case the principal function of a bug report is to help the
5817 entire community by making the next version of @command{@value{AS}} work better.
5818 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5820 In order for a bug report to serve its purpose, you must include the
5821 information that enables us to fix the bug.
5824 * Bug Criteria:: Have you found a bug?
5825 * Bug Reporting:: How to report bugs
5829 @section Have you found a bug?
5830 @cindex bug criteria
5832 If you are not sure whether you have found a bug, here are some guidelines:
5835 @cindex fatal signal
5836 @cindex assembler crash
5837 @cindex crash of assembler
5839 If the assembler gets a fatal signal, for any input whatever, that is a
5840 @command{@value{AS}} bug. Reliable assemblers never crash.
5842 @cindex error on valid input
5844 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5846 @cindex invalid input
5848 If @command{@value{AS}} does not produce an error message for invalid input, that
5849 is a bug. However, you should note that your idea of ``invalid input'' might
5850 be our idea of ``an extension'' or ``support for traditional practice''.
5853 If you are an experienced user of assemblers, your suggestions for improvement
5854 of @command{@value{AS}} are welcome in any case.
5858 @section How to report bugs
5860 @cindex assembler bugs, reporting
5862 A number of companies and individuals offer support for @sc{gnu} products. If
5863 you obtained @command{@value{AS}} from a support organization, we recommend you
5864 contact that organization first.
5866 You can find contact information for many support companies and
5867 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5870 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5871 to @samp{bug-binutils@@gnu.org}.
5873 The fundamental principle of reporting bugs usefully is this:
5874 @strong{report all the facts}. If you are not sure whether to state a
5875 fact or leave it out, state it!
5877 Often people omit facts because they think they know what causes the problem
5878 and assume that some details do not matter. Thus, you might assume that the
5879 name of a symbol you use in an example does not matter. Well, probably it does
5880 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5881 happens to fetch from the location where that name is stored in memory;
5882 perhaps, if the name were different, the contents of that location would fool
5883 the assembler into doing the right thing despite the bug. Play it safe and
5884 give a specific, complete example. That is the easiest thing for you to do,
5885 and the most helpful.
5887 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5888 it is new to us. Therefore, always write your bug reports on the assumption
5889 that the bug has not been reported previously.
5891 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5892 bell?'' Those bug reports are useless, and we urge everyone to
5893 @emph{refuse to respond to them} except to chide the sender to report
5896 To enable us to fix the bug, you should include all these things:
5900 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5901 it with the @samp{--version} argument.
5903 Without this, we will not know whether there is any point in looking for
5904 the bug in the current version of @command{@value{AS}}.
5907 Any patches you may have applied to the @command{@value{AS}} source.
5910 The type of machine you are using, and the operating system name and
5914 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5918 The command arguments you gave the assembler to assemble your example and
5919 observe the bug. To guarantee you will not omit something important, list them
5920 all. A copy of the Makefile (or the output from make) is sufficient.
5922 If we were to try to guess the arguments, we would probably guess wrong
5923 and then we might not encounter the bug.
5926 A complete input file that will reproduce the bug. If the bug is observed when
5927 the assembler is invoked via a compiler, send the assembler source, not the
5928 high level language source. Most compilers will produce the assembler source
5929 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5930 the options @samp{-v --save-temps}; this will save the assembler source in a
5931 file with an extension of @file{.s}, and also show you exactly how
5932 @command{@value{AS}} is being run.
5935 A description of what behavior you observe that you believe is
5936 incorrect. For example, ``It gets a fatal signal.''
5938 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5939 will certainly notice it. But if the bug is incorrect output, we might not
5940 notice unless it is glaringly wrong. You might as well not give us a chance to
5943 Even if the problem you experience is a fatal signal, you should still say so
5944 explicitly. Suppose something strange is going on, such as, your copy of
5945 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5946 library on your system. (This has happened!) Your copy might crash and ours
5947 would not. If you told us to expect a crash, then when ours fails to crash, we
5948 would know that the bug was not happening for us. If you had not told us to
5949 expect a crash, then we would not be able to draw any conclusion from our
5953 If you wish to suggest changes to the @command{@value{AS}} source, send us context
5954 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5955 option. Always send diffs from the old file to the new file. If you even
5956 discuss something in the @command{@value{AS}} source, refer to it by context, not
5959 The line numbers in our development sources will not match those in your
5960 sources. Your line numbers would convey no useful information to us.
5963 Here are some things that are not necessary:
5967 A description of the envelope of the bug.
5969 Often people who encounter a bug spend a lot of time investigating
5970 which changes to the input file will make the bug go away and which
5971 changes will not affect it.
5973 This is often time consuming and not very useful, because the way we
5974 will find the bug is by running a single example under the debugger
5975 with breakpoints, not by pure deduction from a series of examples.
5976 We recommend that you save your time for something else.
5978 Of course, if you can find a simpler example to report @emph{instead}
5979 of the original one, that is a convenience for us. Errors in the
5980 output will be easier to spot, running under the debugger will take
5981 less time, and so on.
5983 However, simplification is not vital; if you do not want to do this,
5984 report the bug anyway and send us the entire test case you used.
5987 A patch for the bug.
5989 A patch for the bug does help us if it is a good one. But do not omit
5990 the necessary information, such as the test case, on the assumption that
5991 a patch is all we need. We might see problems with your patch and decide
5992 to fix the problem another way, or we might not understand it at all.
5994 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
5995 construct an example that will make the program follow a certain path through
5996 the code. If you do not send us the example, we will not be able to construct
5997 one, so we will not be able to verify that the bug is fixed.
5999 And if we cannot understand what bug you are trying to fix, or why your
6000 patch should be an improvement, we will not install it. A test case will
6001 help us to understand.
6004 A guess about what the bug is or what it depends on.
6006 Such guesses are usually wrong. Even we cannot guess right about such
6007 things without first using the debugger to find the facts.
6010 @node Acknowledgements
6011 @chapter Acknowledgements
6013 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6014 it is not meant as a slight. We just don't know about it. Send mail to the
6015 maintainer, and we'll correct the situation. Currently
6017 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6019 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6022 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6023 information and the 68k series machines, most of the preprocessing pass, and
6024 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6026 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6027 many bug fixes, including merging support for several processors, breaking GAS
6028 up to handle multiple object file format back ends (including heavy rewrite,
6029 testing, an integration of the coff and b.out back ends), adding configuration
6030 including heavy testing and verification of cross assemblers and file splits
6031 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6032 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6033 port (including considerable amounts of reverse engineering), a SPARC opcode
6034 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6035 assertions and made them work, much other reorganization, cleanup, and lint.
6037 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6038 in format-specific I/O modules.
6040 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6041 has done much work with it since.
6043 The Intel 80386 machine description was written by Eliot Dresselhaus.
6045 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6047 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6048 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6050 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6051 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6052 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6053 support a.out format.
6055 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6056 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6057 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6058 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6061 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6062 simplified the configuration of which versions accept which directives. He
6063 updated the 68k machine description so that Motorola's opcodes always produced
6064 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6065 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6066 cross-compilation support, and one bug in relaxation that took a week and
6067 required the proverbial one-bit fix.
6069 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6070 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6071 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6072 PowerPC assembler, and made a few other minor patches.
6074 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6076 Hewlett-Packard contributed support for the HP9000/300.
6078 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6079 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6080 formats). This work was supported by both the Center for Software Science at
6081 the University of Utah and Cygnus Support.
6083 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6084 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6085 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6086 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6087 and some initial 64-bit support).
6089 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6091 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6092 support for openVMS/Alpha.
6094 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6097 Several engineers at Cygnus Support have also provided many small bug fixes and
6098 configuration enhancements.
6100 Many others have contributed large or small bugfixes and enhancements. If
6101 you have contributed significant work and are not mentioned on this list, and
6102 want to be, let us know. Some of the history has been lost; we are not
6103 intentionally leaving anyone out.
6105 @node GNU Free Documentation License
6106 @chapter GNU Free Documentation License
6108 GNU Free Documentation License
6110 Version 1.1, March 2000
6112 Copyright (C) 2000 Free Software Foundation, Inc.
6113 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6115 Everyone is permitted to copy and distribute verbatim copies
6116 of this license document, but changing it is not allowed.
6121 The purpose of this License is to make a manual, textbook, or other
6122 written document "free" in the sense of freedom: to assure everyone
6123 the effective freedom to copy and redistribute it, with or without
6124 modifying it, either commercially or noncommercially. Secondarily,
6125 this License preserves for the author and publisher a way to get
6126 credit for their work, while not being considered responsible for
6127 modifications made by others.
6129 This License is a kind of "copyleft", which means that derivative
6130 works of the document must themselves be free in the same sense. It
6131 complements the GNU General Public License, which is a copyleft
6132 license designed for free software.
6134 We have designed this License in order to use it for manuals for free
6135 software, because free software needs free documentation: a free
6136 program should come with manuals providing the same freedoms that the
6137 software does. But this License is not limited to software manuals;
6138 it can be used for any textual work, regardless of subject matter or
6139 whether it is published as a printed book. We recommend this License
6140 principally for works whose purpose is instruction or reference.
6143 1. APPLICABILITY AND DEFINITIONS
6145 This License applies to any manual or other work that contains a
6146 notice placed by the copyright holder saying it can be distributed
6147 under the terms of this License. The "Document", below, refers to any
6148 such manual or work. Any member of the public is a licensee, and is
6151 A "Modified Version" of the Document means any work containing the
6152 Document or a portion of it, either copied verbatim, or with
6153 modifications and/or translated into another language.
6155 A "Secondary Section" is a named appendix or a front-matter section of
6156 the Document that deals exclusively with the relationship of the
6157 publishers or authors of the Document to the Document's overall subject
6158 (or to related matters) and contains nothing that could fall directly
6159 within that overall subject. (For example, if the Document is in part a
6160 textbook of mathematics, a Secondary Section may not explain any
6161 mathematics.) The relationship could be a matter of historical
6162 connection with the subject or with related matters, or of legal,
6163 commercial, philosophical, ethical or political position regarding
6166 The "Invariant Sections" are certain Secondary Sections whose titles
6167 are designated, as being those of Invariant Sections, in the notice
6168 that says that the Document is released under this License.
6170 The "Cover Texts" are certain short passages of text that are listed,
6171 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6172 the Document is released under this License.
6174 A "Transparent" copy of the Document means a machine-readable copy,
6175 represented in a format whose specification is available to the
6176 general public, whose contents can be viewed and edited directly and
6177 straightforwardly with generic text editors or (for images composed of
6178 pixels) generic paint programs or (for drawings) some widely available
6179 drawing editor, and that is suitable for input to text formatters or
6180 for automatic translation to a variety of formats suitable for input
6181 to text formatters. A copy made in an otherwise Transparent file
6182 format whose markup has been designed to thwart or discourage
6183 subsequent modification by readers is not Transparent. A copy that is
6184 not "Transparent" is called "Opaque".
6186 Examples of suitable formats for Transparent copies include plain
6187 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6188 or XML using a publicly available DTD, and standard-conforming simple
6189 HTML designed for human modification. Opaque formats include
6190 PostScript, PDF, proprietary formats that can be read and edited only
6191 by proprietary word processors, SGML or XML for which the DTD and/or
6192 processing tools are not generally available, and the
6193 machine-generated HTML produced by some word processors for output
6196 The "Title Page" means, for a printed book, the title page itself,
6197 plus such following pages as are needed to hold, legibly, the material
6198 this License requires to appear in the title page. For works in
6199 formats which do not have any title page as such, "Title Page" means
6200 the text near the most prominent appearance of the work's title,
6201 preceding the beginning of the body of the text.
6206 You may copy and distribute the Document in any medium, either
6207 commercially or noncommercially, provided that this License, the
6208 copyright notices, and the license notice saying this License applies
6209 to the Document are reproduced in all copies, and that you add no other
6210 conditions whatsoever to those of this License. You may not use
6211 technical measures to obstruct or control the reading or further
6212 copying of the copies you make or distribute. However, you may accept
6213 compensation in exchange for copies. If you distribute a large enough
6214 number of copies you must also follow the conditions in section 3.
6216 You may also lend copies, under the same conditions stated above, and
6217 you may publicly display copies.
6220 3. COPYING IN QUANTITY
6222 If you publish printed copies of the Document numbering more than 100,
6223 and the Document's license notice requires Cover Texts, you must enclose
6224 the copies in covers that carry, clearly and legibly, all these Cover
6225 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6226 the back cover. Both covers must also clearly and legibly identify
6227 you as the publisher of these copies. The front cover must present
6228 the full title with all words of the title equally prominent and
6229 visible. You may add other material on the covers in addition.
6230 Copying with changes limited to the covers, as long as they preserve
6231 the title of the Document and satisfy these conditions, can be treated
6232 as verbatim copying in other respects.
6234 If the required texts for either cover are too voluminous to fit
6235 legibly, you should put the first ones listed (as many as fit
6236 reasonably) on the actual cover, and continue the rest onto adjacent
6239 If you publish or distribute Opaque copies of the Document numbering
6240 more than 100, you must either include a machine-readable Transparent
6241 copy along with each Opaque copy, or state in or with each Opaque copy
6242 a publicly-accessible computer-network location containing a complete
6243 Transparent copy of the Document, free of added material, which the
6244 general network-using public has access to download anonymously at no
6245 charge using public-standard network protocols. If you use the latter
6246 option, you must take reasonably prudent steps, when you begin
6247 distribution of Opaque copies in quantity, to ensure that this
6248 Transparent copy will remain thus accessible at the stated location
6249 until at least one year after the last time you distribute an Opaque
6250 copy (directly or through your agents or retailers) of that edition to
6253 It is requested, but not required, that you contact the authors of the
6254 Document well before redistributing any large number of copies, to give
6255 them a chance to provide you with an updated version of the Document.
6260 You may copy and distribute a Modified Version of the Document under
6261 the conditions of sections 2 and 3 above, provided that you release
6262 the Modified Version under precisely this License, with the Modified
6263 Version filling the role of the Document, thus licensing distribution
6264 and modification of the Modified Version to whoever possesses a copy
6265 of it. In addition, you must do these things in the Modified Version:
6267 A. Use in the Title Page (and on the covers, if any) a title distinct
6268 from that of the Document, and from those of previous versions
6269 (which should, if there were any, be listed in the History section
6270 of the Document). You may use the same title as a previous version
6271 if the original publisher of that version gives permission.
6272 B. List on the Title Page, as authors, one or more persons or entities
6273 responsible for authorship of the modifications in the Modified
6274 Version, together with at least five of the principal authors of the
6275 Document (all of its principal authors, if it has less than five).
6276 C. State on the Title page the name of the publisher of the
6277 Modified Version, as the publisher.
6278 D. Preserve all the copyright notices of the Document.
6279 E. Add an appropriate copyright notice for your modifications
6280 adjacent to the other copyright notices.
6281 F. Include, immediately after the copyright notices, a license notice
6282 giving the public permission to use the Modified Version under the
6283 terms of this License, in the form shown in the Addendum below.
6284 G. Preserve in that license notice the full lists of Invariant Sections
6285 and required Cover Texts given in the Document's license notice.
6286 H. Include an unaltered copy of this License.
6287 I. Preserve the section entitled "History", and its title, and add to
6288 it an item stating at least the title, year, new authors, and
6289 publisher of the Modified Version as given on the Title Page. If
6290 there is no section entitled "History" in the Document, create one
6291 stating the title, year, authors, and publisher of the Document as
6292 given on its Title Page, then add an item describing the Modified
6293 Version as stated in the previous sentence.
6294 J. Preserve the network location, if any, given in the Document for
6295 public access to a Transparent copy of the Document, and likewise
6296 the network locations given in the Document for previous versions
6297 it was based on. These may be placed in the "History" section.
6298 You may omit a network location for a work that was published at
6299 least four years before the Document itself, or if the original
6300 publisher of the version it refers to gives permission.
6301 K. In any section entitled "Acknowledgements" or "Dedications",
6302 preserve the section's title, and preserve in the section all the
6303 substance and tone of each of the contributor acknowledgements
6304 and/or dedications given therein.
6305 L. Preserve all the Invariant Sections of the Document,
6306 unaltered in their text and in their titles. Section numbers
6307 or the equivalent are not considered part of the section titles.
6308 M. Delete any section entitled "Endorsements". Such a section
6309 may not be included in the Modified Version.
6310 N. Do not retitle any existing section as "Endorsements"
6311 or to conflict in title with any Invariant Section.
6313 If the Modified Version includes new front-matter sections or
6314 appendices that qualify as Secondary Sections and contain no material
6315 copied from the Document, you may at your option designate some or all
6316 of these sections as invariant. To do this, add their titles to the
6317 list of Invariant Sections in the Modified Version's license notice.
6318 These titles must be distinct from any other section titles.
6320 You may add a section entitled "Endorsements", provided it contains
6321 nothing but endorsements of your Modified Version by various
6322 parties--for example, statements of peer review or that the text has
6323 been approved by an organization as the authoritative definition of a
6326 You may add a passage of up to five words as a Front-Cover Text, and a
6327 passage of up to 25 words as a Back-Cover Text, to the end of the list
6328 of Cover Texts in the Modified Version. Only one passage of
6329 Front-Cover Text and one of Back-Cover Text may be added by (or
6330 through arrangements made by) any one entity. If the Document already
6331 includes a cover text for the same cover, previously added by you or
6332 by arrangement made by the same entity you are acting on behalf of,
6333 you may not add another; but you may replace the old one, on explicit
6334 permission from the previous publisher that added the old one.
6336 The author(s) and publisher(s) of the Document do not by this License
6337 give permission to use their names for publicity for or to assert or
6338 imply endorsement of any Modified Version.
6341 5. COMBINING DOCUMENTS
6343 You may combine the Document with other documents released under this
6344 License, under the terms defined in section 4 above for modified
6345 versions, provided that you include in the combination all of the
6346 Invariant Sections of all of the original documents, unmodified, and
6347 list them all as Invariant Sections of your combined work in its
6350 The combined work need only contain one copy of this License, and
6351 multiple identical Invariant Sections may be replaced with a single
6352 copy. If there are multiple Invariant Sections with the same name but
6353 different contents, make the title of each such section unique by
6354 adding at the end of it, in parentheses, the name of the original
6355 author or publisher of that section if known, or else a unique number.
6356 Make the same adjustment to the section titles in the list of
6357 Invariant Sections in the license notice of the combined work.
6359 In the combination, you must combine any sections entitled "History"
6360 in the various original documents, forming one section entitled
6361 "History"; likewise combine any sections entitled "Acknowledgements",
6362 and any sections entitled "Dedications". You must delete all sections
6363 entitled "Endorsements."
6366 6. COLLECTIONS OF DOCUMENTS
6368 You may make a collection consisting of the Document and other documents
6369 released under this License, and replace the individual copies of this
6370 License in the various documents with a single copy that is included in
6371 the collection, provided that you follow the rules of this License for
6372 verbatim copying of each of the documents in all other respects.
6374 You may extract a single document from such a collection, and distribute
6375 it individually under this License, provided you insert a copy of this
6376 License into the extracted document, and follow this License in all
6377 other respects regarding verbatim copying of that document.
6380 7. AGGREGATION WITH INDEPENDENT WORKS
6382 A compilation of the Document or its derivatives with other separate
6383 and independent documents or works, in or on a volume of a storage or
6384 distribution medium, does not as a whole count as a Modified Version
6385 of the Document, provided no compilation copyright is claimed for the
6386 compilation. Such a compilation is called an "aggregate", and this
6387 License does not apply to the other self-contained works thus compiled
6388 with the Document, on account of their being thus compiled, if they
6389 are not themselves derivative works of the Document.
6391 If the Cover Text requirement of section 3 is applicable to these
6392 copies of the Document, then if the Document is less than one quarter
6393 of the entire aggregate, the Document's Cover Texts may be placed on
6394 covers that surround only the Document within the aggregate.
6395 Otherwise they must appear on covers around the whole aggregate.
6400 Translation is considered a kind of modification, so you may
6401 distribute translations of the Document under the terms of section 4.
6402 Replacing Invariant Sections with translations requires special
6403 permission from their copyright holders, but you may include
6404 translations of some or all Invariant Sections in addition to the
6405 original versions of these Invariant Sections. You may include a
6406 translation of this License provided that you also include the
6407 original English version of this License. In case of a disagreement
6408 between the translation and the original English version of this
6409 License, the original English version will prevail.
6414 You may not copy, modify, sublicense, or distribute the Document except
6415 as expressly provided for under this License. Any other attempt to
6416 copy, modify, sublicense or distribute the Document is void, and will
6417 automatically terminate your rights under this License. However,
6418 parties who have received copies, or rights, from you under this
6419 License will not have their licenses terminated so long as such
6420 parties remain in full compliance.
6423 10. FUTURE REVISIONS OF THIS LICENSE
6425 The Free Software Foundation may publish new, revised versions
6426 of the GNU Free Documentation License from time to time. Such new
6427 versions will be similar in spirit to the present version, but may
6428 differ in detail to address new problems or concerns. See
6429 http://www.gnu.org/copyleft/.
6431 Each version of the License is given a distinguishing version number.
6432 If the Document specifies that a particular numbered version of this
6433 License "or any later version" applies to it, you have the option of
6434 following the terms and conditions either of that specified version or
6435 of any later version that has been published (not as a draft) by the
6436 Free Software Foundation. If the Document does not specify a version
6437 number of this License, you may choose any version ever published (not
6438 as a draft) by the Free Software Foundation.
6441 ADDENDUM: How to use this License for your documents
6443 To use this License in a document you have written, include a copy of
6444 the License in the document and put the following copyright and
6445 license notices just after the title page:
6448 Copyright (c) YEAR YOUR NAME.
6449 Permission is granted to copy, distribute and/or modify this document
6450 under the terms of the GNU Free Documentation License, Version 1.1
6451 or any later version published by the Free Software Foundation;
6452 with the Invariant Sections being LIST THEIR TITLES, with the
6453 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6454 A copy of the license is included in the section entitled "GNU
6455 Free Documentation License".
6458 If you have no Invariant Sections, write "with no Invariant Sections"
6459 instead of saying which ones are invariant. If you have no
6460 Front-Cover Texts, write "no Front-Cover Texts" instead of
6461 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6463 If your document contains nontrivial examples of program code, we
6464 recommend releasing these examples in parallel under your choice of
6465 free software license, such as the GNU General Public License,
6466 to permit their use in free software.
projects / binutils-gdb.git / blob