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
61 @c common OR combinations of conditions
81 @set abnormal-separator
85 @settitle Using @value{AS}
88 @settitle Using @value{AS} (@value{TARGET})
90 @setchapternewpage odd
95 @c WARE! Some of the machine-dependent sections contain tables of machine
96 @c instructions. Except in multi-column format, these tables look silly.
97 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
98 @c the multi-col format is faked within @example sections.
100 @c Again unfortunately, the natural size that fits on a page, for these tables,
101 @c is different depending on whether or not smallbook is turned on.
102 @c This matters, because of order: text flow switches columns at each page
105 @c The format faked in this source works reasonably well for smallbook,
106 @c not well for the default large-page format. This manual expects that if you
107 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
108 @c tables in question. You can turn on one without the other at your
109 @c discretion, of course.
112 @c the insn tables look just as silly in info files regardless of smallbook,
113 @c might as well show 'em anyways.
119 * As: (as). The GNU assembler.
128 This file documents the GNU Assembler "@value{AS}".
130 @c man begin COPYRIGHT
131 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
133 Permission is granted to copy, distribute and/or modify this document
134 under the terms of the GNU Free Documentation License, Version 1.1
135 or any later version published by the Free Software Foundation;
136 with no Invariant Sections, with no Front-Cover Texts, and with no
137 Back-Cover Texts. A copy of the license is included in the
138 section entitled "GNU Free Documentation License".
143 Permission is granted to process this file through Tex and print the
144 results, provided the printed document carries copying permission
145 notice identical to this one except for the removal of this paragraph
146 (this paragraph not being relevant to the printed manual).
152 @title Using @value{AS}
153 @subtitle The @sc{gnu} Assembler
155 @subtitle for the @value{TARGET} family
158 @subtitle Version @value{VERSION}
161 The Free Software Foundation Inc. thanks The Nice Computer
162 Company of Australia for loaning Dean Elsner to write the
163 first (Vax) version of @command{as} for Project @sc{gnu}.
164 The proprietors, management and staff of TNCCA thank FSF for
165 distracting the boss while they got some work
168 @author Dean Elsner, Jay Fenlason & friends
172 \hfill {\it Using {\tt @value{AS}}}\par
173 \hfill Edited by Cygnus Support\par
175 %"boxit" macro for figures:
176 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
177 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
178 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
179 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
180 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
183 @vskip 0pt plus 1filll
184 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
186 Permission is granted to copy, distribute and/or modify this document
187 under the terms of the GNU Free Documentation License, Version 1.1
188 or any later version published by the Free Software Foundation;
189 with no Invariant Sections, with no Front-Cover Texts, and with no
190 Back-Cover Texts. A copy of the license is included in the
191 section entitled "GNU Free Documentation License".
197 @top Using @value{AS}
199 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
202 This version of the file describes @command{@value{AS}} configured to generate
203 code for @value{TARGET} architectures.
206 This document is distributed under the terms of the GNU Free
207 Documentation License. A copy of the license is included in the
208 section entitled "GNU Free Documentation License".
211 * Overview:: Overview
212 * Invoking:: Command-Line Options
214 * Sections:: Sections and Relocation
216 * Expressions:: Expressions
217 * Pseudo Ops:: Assembler Directives
218 * Machine Dependencies:: Machine Dependent Features
219 * Reporting Bugs:: Reporting Bugs
220 * Acknowledgements:: Who Did What
221 * GNU Free Documentation License:: GNU Free Documentation License
229 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
231 This version of the manual describes @command{@value{AS}} configured to generate
232 code for @value{TARGET} architectures.
236 @cindex invocation summary
237 @cindex option summary
238 @cindex summary of options
239 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
240 @pxref{Invoking,,Comand-Line Options}.
242 @c man title AS the portable GNU assembler.
246 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
250 @c We don't use deffn and friends for the following because they seem
251 @c to be limited to one line for the header.
253 @c man begin SYNOPSIS
254 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
255 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
256 [@b{-J}] [@b{-K}] [@b{-L}]
257 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
258 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
259 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
260 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
261 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
262 [@b{--}|@var{files} @dots{}]
264 @c Target dependent options are listed below. Keep the list sorted.
265 @c Add an empty line for separation.
267 @c am29k has no machine-dependent assembler options
271 @emph{Target ARC options:}
277 @emph{Target ARM options:}
278 @c Don't document the deprecated options
279 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
280 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
281 [@b{-mfpu}=@var{floating-point-fromat}]
284 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
285 @b{-mapcs-reentrant}]
286 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
290 @emph{Target CRIS options:}
291 [@b{--underscore} | @b{--no-underscore}]
293 [@b{--emulation=criself} | @b{--emulation=crisaout}]
294 @c Deprecated -- deliberately not documented.
299 @emph{Target D10V options:}
304 @emph{Target D30V options:}
305 [@b{-O}|@b{-n}|@b{-N}]
308 @c Hitachi family chips have no machine-dependent assembler options
311 @c HPPA has no machine-dependent assembler options (yet).
315 @emph{Target i386 options:}
320 @emph{Target i960 options:}
321 @c see md_parse_option in tc-i960.c
322 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
324 [@b{-b}] [@b{-no-relax}]
328 @emph{Target M32R options:}
329 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
334 @emph{Target M680X0 options:}
335 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
339 @emph{Target M68HC11 options:}
340 [@b{-m68hc11}|@b{-m68hc12}]
341 [@b{--force-long-branchs}] [@b{--short-branchs}]
342 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
343 [@b{--print-opcodes}] [@b{--generate-example}]
347 @emph{Target MCORE options:}
348 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
349 [@b{-mcpu=[210|340]}]
353 @emph{Target MIPS options:}
354 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
355 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
356 [@b{-mips32}] [@b{-mips64}]
357 [@b{-m4650}] [@b{-no-m4650}]
358 [@b{--trap}] [@b{--break}] [@b{-n}]
359 [@b{--emulation}=@var{name} ]
363 @emph{Target MMIX options:}
364 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
365 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
366 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
367 [@b{--linker-allocated-gregs}]
371 @emph{Target PDP11 options:}
372 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
373 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
374 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
378 @emph{Target picoJava options:}
383 @emph{Target PowerPC options:}
384 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
385 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
386 @b{-mbooke32}|@b{-mbooke64}]
387 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
388 [@b{-mregnames}|@b{-mno-regnames}]
389 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
390 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
391 [@b{-msolaris}|@b{-mno-solaris}]
395 @emph{Target SPARC options:}
396 @c The order here is important. See c-sparc.texi.
397 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
398 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
399 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
404 @emph{Target TIC54X options:}
405 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
406 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
409 @c Z8000 has no machine-dependent assembler options
418 Turn on listings, in any of a variety of ways:
422 omit false conditionals
425 omit debugging directives
428 include high-level source
434 include macro expansions
437 omit forms processing
443 set the name of the listing file
446 You may combine these options; for example, use @samp{-aln} for assembly
447 listing without forms processing. The @samp{=file} option, if used, must be
448 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
451 Ignored. This option is accepted for script compatibility with calls to
454 @item --defsym @var{sym}=@var{value}
455 Define the symbol @var{sym} to be @var{value} before assembling the input file.
456 @var{value} must be an integer constant. As in C, a leading @samp{0x}
457 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
460 ``fast''---skip whitespace and comment preprocessing (assume source is
464 Generate stabs debugging information for each assembler line. This
465 may help debugging assembler code, if the debugger can handle it.
468 Generate DWARF2 debugging information for each assembler line. This
469 may help debugging assembler code, if the debugger can handle it. Note - this
470 option is only supported by some targets, not all of them.
473 Print a summary of the command line options and exit.
476 Print a summary of all target specific options and exit.
479 Add directory @var{dir} to the search list for @code{.include} directives.
482 Don't warn about signed overflow.
485 @ifclear DIFF-TBL-KLUGE
486 This option is accepted but has no effect on the @value{TARGET} family.
488 @ifset DIFF-TBL-KLUGE
489 Issue warnings when difference tables altered for long displacements.
494 Keep (in the symbol table) local symbols. On traditional a.out systems
495 these start with @samp{L}, but different systems have different local
498 @item --listing-lhs-width=@var{number}
499 Set the maximum width, in words, of the output data column for an assembler
500 listing to @var{number}.
502 @item --listing-lhs-width2=@var{number}
503 Set the maximum width, in words, of the output data column for continuation
504 lines in an assembler listing to @var{number}.
506 @item --listing-rhs-width=@var{number}
507 Set the maximum width of an input source line, as displayed in a listing, to
510 @item --listing-cont-lines=@var{number}
511 Set the maximum number of lines printed in a listing for a single line of input
514 @item -o @var{objfile}
515 Name the object-file output from @command{@value{AS}} @var{objfile}.
518 Fold the data section into the text section.
521 Print the maximum space (in bytes) and total time (in seconds) used by
524 @item --strip-local-absolute
525 Remove local absolute symbols from the outgoing symbol table.
529 Print the @command{as} version.
532 Print the @command{as} version and exit.
536 Suppress warning messages.
538 @item --fatal-warnings
539 Treat warnings as errors.
542 Don't suppress warning messages or treat them as errors.
551 Generate an object file even after errors.
553 @item -- | @var{files} @dots{}
554 Standard input, or source files to assemble.
559 The following options are available when @value{AS} is configured for
564 This option selects the core processor variant.
566 Select either big-endian (-EB) or little-endian (-EL) output.
571 The following options are available when @value{AS} is configured for the ARM
575 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
576 Specify which ARM processor variant is the target.
577 @item -march=@var{architecture}[+@var{extension}@dots{}]
578 Specify which ARM architecture variant is used by the target.
579 @item -mfpu=@var{floating-point-format}
580 Select which Floating Point architecture is the target.
582 Enable Thumb only instruction decoding.
583 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
584 Select which procedure calling convention is in use.
586 Select either big-endian (-EB) or little-endian (-EL) output.
587 @item -mthumb-interwork
588 Specify that the code has been generated with interworking between Thumb and
591 Specify that PIC code has been generated.
596 See the info pages for documentation of the CRIS-specific options.
600 The following options are available when @value{AS} is configured for
603 @cindex D10V optimization
604 @cindex optimization, D10V
606 Optimize output by parallelizing instructions.
611 The following options are available when @value{AS} is configured for a D30V
614 @cindex D30V optimization
615 @cindex optimization, D30V
617 Optimize output by parallelizing instructions.
621 Warn when nops are generated.
623 @cindex D30V nops after 32-bit multiply
625 Warn when a nop after a 32-bit multiply instruction is generated.
630 The following options are available when @value{AS} is configured for the
631 Intel 80960 processor.
634 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
635 Specify which variant of the 960 architecture is the target.
638 Add code to collect statistics about branches taken.
641 Do not alter compare-and-branch instructions for long displacements;
648 The following options are available when @value{AS} is configured for the
649 Mitsubishi M32R series.
654 Specify which processor in the M32R family is the target. The default
655 is normally the M32R, but this option changes it to the M32RX.
657 @item --warn-explicit-parallel-conflicts or --Wp
658 Produce warning messages when questionable parallel constructs are
661 @item --no-warn-explicit-parallel-conflicts or --Wnp
662 Do not produce warning messages when questionable parallel constructs are
669 The following options are available when @value{AS} is configured for the
670 Motorola 68000 series.
675 Shorten references to undefined symbols, to one word instead of two.
677 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
678 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
679 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
680 Specify what processor in the 68000 family is the target. The default
681 is normally the 68020, but this can be changed at configuration time.
683 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
684 The target machine does (or does not) have a floating-point coprocessor.
685 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
686 the basic 68000 is not compatible with the 68881, a combination of the
687 two can be specified, since it's possible to do emulation of the
688 coprocessor instructions with the main processor.
690 @item -m68851 | -mno-68851
691 The target machine does (or does not) have a memory-management
692 unit coprocessor. The default is to assume an MMU for 68020 and up.
699 For details about the PDP-11 machine dependent features options,
700 see @ref{PDP-11-Options}.
703 @item -mpic | -mno-pic
704 Generate position-independent (or position-dependent) code. The
705 default is @option{-mpic}.
708 @itemx -mall-extensions
709 Enable all instruction set extensions. This is the default.
711 @item -mno-extensions
712 Disable all instruction set extensions.
714 @item -m@var{extension} | -mno-@var{extension}
715 Enable (or disable) a particular instruction set extension.
718 Enable the instruction set extensions supported by a particular CPU, and
719 disable all other extensions.
721 @item -m@var{machine}
722 Enable the instruction set extensions supported by a particular machine
723 model, and disable all other extensions.
729 The following options are available when @value{AS} is configured for
730 a picoJava processor.
734 @cindex PJ endianness
735 @cindex endianness, PJ
736 @cindex big endian output, PJ
738 Generate ``big endian'' format output.
740 @cindex little endian output, PJ
742 Generate ``little endian'' format output.
748 The following options are available when @value{AS} is configured for the
749 Motorola 68HC11 or 68HC12 series.
753 @item -m68hc11 | -m68hc12
754 Specify what processor is the target. The default is
755 defined by the configuration option when building the assembler.
757 @item --force-long-branchs
758 Relative branches are turned into absolute ones. This concerns
759 conditional branches, unconditional branches and branches to a
762 @item -S | --short-branchs
763 Do not turn relative branchs into absolute ones
764 when the offset is out of range.
766 @item --strict-direct-mode
767 Do not turn the direct addressing mode into extended addressing mode
768 when the instruction does not support direct addressing mode.
770 @item --print-insn-syntax
771 Print the syntax of instruction in case of error.
773 @item --print-opcodes
774 print the list of instructions with syntax and then exit.
776 @item --generate-example
777 print an example of instruction for each possible instruction and then exit.
778 This option is only useful for testing @command{@value{AS}}.
784 The following options are available when @command{@value{AS}} is configured
785 for the SPARC architecture:
788 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
789 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
790 Explicitly select a variant of the SPARC architecture.
792 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
793 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
795 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
796 UltraSPARC extensions.
798 @item -xarch=v8plus | -xarch=v8plusa
799 For compatibility with the Solaris v9 assembler. These options are
800 equivalent to -Av8plus and -Av8plusa, respectively.
803 Warn when the assembler switches to another architecture.
808 The following options are available when @value{AS} is configured for the 'c54x
813 Enable extended addressing mode. All addresses and relocations will assume
814 extended addressing (usually 23 bits).
815 @item -mcpu=@var{CPU_VERSION}
816 Sets the CPU version being compiled for.
817 @item -merrors-to-file @var{FILENAME}
818 Redirect error output to a file, for broken systems which don't support such
819 behaviour in the shell.
824 The following options are available when @value{AS} is configured for
829 This option sets the largest size of an object that can be referenced
830 implicitly with the @code{gp} register. It is only accepted for targets that
831 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
833 @cindex MIPS endianness
834 @cindex endianness, MIPS
835 @cindex big endian output, MIPS
837 Generate ``big endian'' format output.
839 @cindex little endian output, MIPS
841 Generate ``little endian'' format output.
850 Generate code for a particular MIPS Instruction Set Architecture level.
851 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
852 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
854 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
855 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
856 processors, respectively.
860 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
861 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
862 instructions around accesses to the @samp{HI} and @samp{LO} registers.
863 @samp{-no-m4650} turns off this option.
865 @item -mcpu=@var{CPU}
866 Generate code for a particular MIPS cpu. It is exactly equivalent to
867 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
871 @item --emulation=@var{name}
872 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
873 for some other target, in all respects, including output format (choosing
874 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
875 debugging information or store symbol table information, and default
876 endianness. The available configuration names are: @samp{mipsecoff},
877 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
878 @samp{mipsbelf}. The first two do not alter the default endianness from that
879 of the primary target for which the assembler was configured; the others change
880 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
881 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
882 selection in any case.
884 This option is currently supported only when the primary target
885 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
886 Furthermore, the primary target or others specified with
887 @samp{--enable-targets=@dots{}} at configuration time must include support for
888 the other format, if both are to be available. For example, the Irix 5
889 configuration includes support for both.
891 Eventually, this option will support more configurations, with more
892 fine-grained control over the assembler's behavior, and will be supported for
896 @command{@value{AS}} ignores this option. It is accepted for compatibility with
904 Control how to deal with multiplication overflow and division by zero.
905 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
906 (and only work for Instruction Set Architecture level 2 and higher);
907 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
911 When this option is used, @command{@value{AS}} will issue a warning every
912 time it generates a nop instruction from a macro.
917 The following options are available when @value{AS} is configured for
923 Enable or disable the JSRI to BSR transformation. By default this is enabled.
924 The command line option @samp{-nojsri2bsr} can be used to disable it.
928 Enable or disable the silicon filter behaviour. By default this is disabled.
929 The default can be overridden by the @samp{-sifilter} command line option.
932 Alter jump instructions for long displacements.
934 @item -mcpu=[210|340]
935 Select the cpu type on the target hardware. This controls which instructions
939 Assemble for a big endian target.
942 Assemble for a little endian target.
948 See the info pages for documentation of the MMIX-specific options.
954 * Manual:: Structure of this Manual
955 * GNU Assembler:: The GNU Assembler
956 * Object Formats:: Object File Formats
957 * Command Line:: Command Line
958 * Input Files:: Input Files
959 * Object:: Output (Object) File
960 * Errors:: Error and Warning Messages
964 @section Structure of this Manual
966 @cindex manual, structure and purpose
967 This manual is intended to describe what you need to know to use
968 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
969 notation for symbols, constants, and expressions; the directives that
970 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
973 We also cover special features in the @value{TARGET}
974 configuration of @command{@value{AS}}, including assembler directives.
977 This manual also describes some of the machine-dependent features of
978 various flavors of the assembler.
981 @cindex machine instructions (not covered)
982 On the other hand, this manual is @emph{not} intended as an introduction
983 to programming in assembly language---let alone programming in general!
984 In a similar vein, we make no attempt to introduce the machine
985 architecture; we do @emph{not} describe the instruction set, standard
986 mnemonics, registers or addressing modes that are standard to a
987 particular architecture.
989 You may want to consult the manufacturer's
990 machine architecture manual for this information.
994 For information on the H8/300 machine instruction set, see @cite{H8/300
995 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
996 see @cite{H8/300H Series Programming Manual} (Hitachi).
999 For information on the H8/500 machine instruction set, see @cite{H8/500
1000 Series Programming Manual} (Hitachi M21T001).
1003 For information on the Hitachi SH machine instruction set, see
1004 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1007 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1011 @c I think this is premature---doc@cygnus.com, 17jan1991
1013 Throughout this manual, we assume that you are running @dfn{GNU},
1014 the portable operating system from the @dfn{Free Software
1015 Foundation, Inc.}. This restricts our attention to certain kinds of
1016 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1017 once this assumption is granted examples and definitions need less
1020 @command{@value{AS}} is part of a team of programs that turn a high-level
1021 human-readable series of instructions into a low-level
1022 computer-readable series of instructions. Different versions of
1023 @command{@value{AS}} are used for different kinds of computer.
1026 @c There used to be a section "Terminology" here, which defined
1027 @c "contents", "byte", "word", and "long". Defining "word" to any
1028 @c particular size is confusing when the .word directive may generate 16
1029 @c bits on one machine and 32 bits on another; in general, for the user
1030 @c version of this manual, none of these terms seem essential to define.
1031 @c They were used very little even in the former draft of the manual;
1032 @c this draft makes an effort to avoid them (except in names of
1036 @section The GNU Assembler
1038 @c man begin DESCRIPTION
1040 @sc{gnu} @command{as} is really a family of assemblers.
1042 This manual describes @command{@value{AS}}, a member of that family which is
1043 configured for the @value{TARGET} architectures.
1045 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1046 should find a fairly similar environment when you use it on another
1047 architecture. Each version has much in common with the others,
1048 including object file formats, most assembler directives (often called
1049 @dfn{pseudo-ops}) and assembler syntax.@refill
1051 @cindex purpose of @sc{gnu} assembler
1052 @command{@value{AS}} is primarily intended to assemble the output of the
1053 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1054 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1055 assemble correctly everything that other assemblers for the same
1056 machine would assemble.
1058 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1061 @c This remark should appear in generic version of manual; assumption
1062 @c here is that generic version sets M680x0.
1063 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1064 assembler for the same architecture; for example, we know of several
1065 incompatible versions of 680x0 assembly language syntax.
1070 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1071 program in one pass of the source file. This has a subtle impact on the
1072 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1074 @node Object Formats
1075 @section Object File Formats
1077 @cindex object file format
1078 The @sc{gnu} assembler can be configured to produce several alternative
1079 object file formats. For the most part, this does not affect how you
1080 write assembly language programs; but directives for debugging symbols
1081 are typically different in different file formats. @xref{Symbol
1082 Attributes,,Symbol Attributes}.
1085 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1086 @value{OBJ-NAME} format object files.
1088 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1090 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1091 @code{a.out} or COFF format object files.
1094 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1095 @code{b.out} or COFF format object files.
1098 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1099 SOM or ELF format object files.
1104 @section Command Line
1106 @cindex command line conventions
1108 After the program name @command{@value{AS}}, the command line may contain
1109 options and file names. Options may appear in any order, and may be
1110 before, after, or between file names. The order of file names is
1113 @cindex standard input, as input file
1115 @file{--} (two hyphens) by itself names the standard input file
1116 explicitly, as one of the files for @command{@value{AS}} to assemble.
1118 @cindex options, command line
1119 Except for @samp{--} any command line argument that begins with a
1120 hyphen (@samp{-}) is an option. Each option changes the behavior of
1121 @command{@value{AS}}. No option changes the way another option works. An
1122 option is a @samp{-} followed by one or more letters; the case of
1123 the letter is important. All options are optional.
1125 Some options expect exactly one file name to follow them. The file
1126 name may either immediately follow the option's letter (compatible
1127 with older assemblers) or it may be the next command argument (@sc{gnu}
1128 standard). These two command lines are equivalent:
1131 @value{AS} -o my-object-file.o mumble.s
1132 @value{AS} -omy-object-file.o mumble.s
1136 @section Input Files
1139 @cindex source program
1140 @cindex files, input
1141 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1142 describe the program input to one run of @command{@value{AS}}. The program may
1143 be in one or more files; how the source is partitioned into files
1144 doesn't change the meaning of the source.
1146 @c I added "con" prefix to "catenation" just to prove I can overcome my
1147 @c APL training... doc@cygnus.com
1148 The source program is a concatenation of the text in all the files, in the
1151 @c man begin DESCRIPTION
1152 Each time you run @command{@value{AS}} it assembles exactly one source
1153 program. The source program is made up of one or more files.
1154 (The standard input is also a file.)
1156 You give @command{@value{AS}} a command line that has zero or more input file
1157 names. The input files are read (from left file name to right). A
1158 command line argument (in any position) that has no special meaning
1159 is taken to be an input file name.
1161 If you give @command{@value{AS}} no file names it attempts to read one input file
1162 from the @command{@value{AS}} standard input, which is normally your terminal. You
1163 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1166 Use @samp{--} if you need to explicitly name the standard input file
1167 in your command line.
1169 If the source is empty, @command{@value{AS}} produces a small, empty object
1174 @subheading Filenames and Line-numbers
1176 @cindex input file linenumbers
1177 @cindex line numbers, in input files
1178 There are two ways of locating a line in the input file (or files) and
1179 either may be used in reporting error messages. One way refers to a line
1180 number in a physical file; the other refers to a line number in a
1181 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1183 @dfn{Physical files} are those files named in the command line given
1184 to @command{@value{AS}}.
1186 @dfn{Logical files} are simply names declared explicitly by assembler
1187 directives; they bear no relation to physical files. Logical file names help
1188 error messages reflect the original source file, when @command{@value{AS}} source
1189 is itself synthesized from other files. @command{@value{AS}} understands the
1190 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1191 @ref{File,,@code{.file}}.
1194 @section Output (Object) File
1200 Every time you run @command{@value{AS}} it produces an output file, which is
1201 your assembly language program translated into numbers. This file
1202 is the object file. Its default name is
1210 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1212 You can give it another name by using the @option{-o} option. Conventionally,
1213 object file names end with @file{.o}. The default name is used for historical
1214 reasons: older assemblers were capable of assembling self-contained programs
1215 directly into a runnable program. (For some formats, this isn't currently
1216 possible, but it can be done for the @code{a.out} format.)
1220 The object file is meant for input to the linker @code{@value{LD}}. It contains
1221 assembled program code, information to help @code{@value{LD}} integrate
1222 the assembled program into a runnable file, and (optionally) symbolic
1223 information for the debugger.
1225 @c link above to some info file(s) like the description of a.out.
1226 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1229 @section Error and Warning Messages
1231 @c man begin DESCRIPTION
1233 @cindex error messages
1234 @cindex warning messages
1235 @cindex messages from assembler
1236 @command{@value{AS}} may write warnings and error messages to the standard error
1237 file (usually your terminal). This should not happen when a compiler
1238 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1239 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1240 grave problem that stops the assembly.
1244 @cindex format of warning messages
1245 Warning messages have the format
1248 file_name:@b{NNN}:Warning Message Text
1252 @cindex line numbers, in warnings/errors
1253 (where @b{NNN} is a line number). If a logical file name has been given
1254 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1255 the current input file is used. If a logical line number was given
1257 (@pxref{Line,,@code{.line}})
1261 (@pxref{Line,,@code{.line}})
1264 (@pxref{Ln,,@code{.ln}})
1267 then it is used to calculate the number printed,
1268 otherwise the actual line in the current source file is printed. The
1269 message text is intended to be self explanatory (in the grand Unix
1272 @cindex format of error messages
1273 Error messages have the format
1275 file_name:@b{NNN}:FATAL:Error Message Text
1277 The file name and line number are derived as for warning
1278 messages. The actual message text may be rather less explanatory
1279 because many of them aren't supposed to happen.
1282 @chapter Command-Line Options
1284 @cindex options, all versions of assembler
1285 This chapter describes command-line options available in @emph{all}
1286 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1288 to the @value{TARGET}.
1291 to particular machine architectures.
1294 @c man begin DESCRIPTION
1296 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1297 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1298 The assembler arguments must be separated from each other (and the @samp{-Wa})
1299 by commas. For example:
1302 gcc -c -g -O -Wa,-alh,-L file.c
1306 This passes two options to the assembler: @samp{-alh} (emit a listing to
1307 standard output with with high-level and assembly source) and @samp{-L} (retain
1308 local symbols in the symbol table).
1310 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1311 command-line options are automatically passed to the assembler by the compiler.
1312 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1313 precisely what options it passes to each compilation pass, including the
1319 * a:: -a[cdhlns] enable listings
1320 * D:: -D for compatibility
1321 * f:: -f to work faster
1322 * I:: -I for .include search path
1323 @ifclear DIFF-TBL-KLUGE
1324 * K:: -K for compatibility
1326 @ifset DIFF-TBL-KLUGE
1327 * K:: -K for difference tables
1330 * L:: -L to retain local labels
1331 * listing:: --listing-XXX to configure listing output
1332 * M:: -M or --mri to assemble in MRI compatibility mode
1333 * MD:: --MD for dependency tracking
1334 * o:: -o to name the object file
1335 * R:: -R to join data and text sections
1336 * statistics:: --statistics to see statistics about assembly
1337 * traditional-format:: --traditional-format for compatible output
1338 * v:: -v to announce version
1339 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1340 * Z:: -Z to make object file even after errors
1344 @section Enable Listings: @option{-a[cdhlns]}
1353 @cindex listings, enabling
1354 @cindex assembly listings, enabling
1356 These options enable listing output from the assembler. By itself,
1357 @samp{-a} requests high-level, assembly, and symbols listing.
1358 You can use other letters to select specific options for the list:
1359 @samp{-ah} requests a high-level language listing,
1360 @samp{-al} requests an output-program assembly listing, and
1361 @samp{-as} requests a symbol table listing.
1362 High-level listings require that a compiler debugging option like
1363 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1366 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1367 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1368 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1369 omitted from the listing.
1371 Use the @samp{-ad} option to omit debugging directives from the
1374 Once you have specified one of these options, you can further control
1375 listing output and its appearance using the directives @code{.list},
1376 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1378 The @samp{-an} option turns off all forms processing.
1379 If you do not request listing output with one of the @samp{-a} options, the
1380 listing-control directives have no effect.
1382 The letters after @samp{-a} may be combined into one option,
1383 @emph{e.g.}, @samp{-aln}.
1385 Note if the assembler source is coming from the standard input (eg because it
1386 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1387 is being used) then the listing will not contain any comments or preprocessor
1388 directives. This is because the listing code buffers input source lines from
1389 stdin only after they have been preprocessed by the assembler. This reduces
1390 memory usage and makes the code more efficient.
1393 @section @option{-D}
1396 This option has no effect whatsoever, but it is accepted to make it more
1397 likely that scripts written for other assemblers also work with
1398 @command{@value{AS}}.
1401 @section Work Faster: @option{-f}
1404 @cindex trusted compiler
1405 @cindex faster processing (@option{-f})
1406 @samp{-f} should only be used when assembling programs written by a
1407 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1408 and comment preprocessing on
1409 the input file(s) before assembling them. @xref{Preprocessing,
1413 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1414 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1419 @section @code{.include} search path: @option{-I} @var{path}
1421 @kindex -I @var{path}
1422 @cindex paths for @code{.include}
1423 @cindex search path for @code{.include}
1424 @cindex @code{include} directive search path
1425 Use this option to add a @var{path} to the list of directories
1426 @command{@value{AS}} searches for files specified in @code{.include}
1427 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1428 many times as necessary to include a variety of paths. The current
1429 working directory is always searched first; after that, @command{@value{AS}}
1430 searches any @samp{-I} directories in the same order as they were
1431 specified (left to right) on the command line.
1434 @section Difference Tables: @option{-K}
1437 @ifclear DIFF-TBL-KLUGE
1438 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1439 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1440 where it can be used to warn when the assembler alters the machine code
1441 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1442 family does not have the addressing limitations that sometimes lead to this
1443 alteration on other platforms.
1446 @ifset DIFF-TBL-KLUGE
1447 @cindex difference tables, warning
1448 @cindex warning for altered difference tables
1449 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1450 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1451 You can use the @samp{-K} option if you want a warning issued when this
1456 @section Include Local Labels: @option{-L}
1459 @cindex local labels, retaining in output
1460 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1461 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1462 debugging, because they are intended for the use of programs (like
1463 compilers) that compose assembler programs, not for your notice.
1464 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1465 normally debug with them.
1467 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1468 in the object file. Usually if you do this you also tell the linker
1469 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1471 By default, a local label is any label beginning with @samp{L}, but each
1472 target is allowed to redefine the local label prefix.
1474 On the HPPA local labels begin with @samp{L$}.
1478 @section Configuring listing output: @option{--listing}
1480 The listing feature of the assembler can be enabled via the command line switch
1481 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1482 hex dump of the corresponding locations in the output object file, and displays
1483 them as a listing file. The format of this listing can be controlled by pseudo
1484 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1485 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1488 @item --listing-lhs-width=@samp{number}
1489 @kindex --listing-lhs-width
1490 @cindex Width of first line disassembly output
1491 Sets the maximum width, in words, of the first line of the hex byte dump. This
1492 dump appears on the left hand side of the listing output.
1494 @item --listing-lhs-width2=@samp{number}
1495 @kindex --listing-lhs-width2
1496 @cindex Width of continuation lines of disassembly output
1497 Sets the maximum width, in words, of any further lines of the hex byte dump for
1498 a given inut source line. If this value is not specified, it defaults to being
1499 the same as the value specified for @samp{--listing-lhs-width}. If neither
1500 switch is used the default is to one.
1502 @item --listing-rhs-width=@samp{number}
1503 @kindex --listing-rhs-width
1504 @cindex Width of source line output
1505 Sets the maximum width, in characters, of the source line that is displayed
1506 alongside the hex dump. The default value for this parameter is 100. The
1507 source line is displayed on the right hand side of the listing output.
1509 @item --listing-cont-lines=@samp{number}
1510 @kindex --listing-cont-lines
1511 @cindex Maximum number of continuation lines
1512 Sets the maximum number of continuation lines of hex dump that will be
1513 displayed for a given single line of source input. The default value is 4.
1517 @section Assemble in MRI Compatibility Mode: @option{-M}
1520 @cindex MRI compatibility mode
1521 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1522 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1523 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1524 configured target) assembler from Microtec Research. The exact nature of the
1525 MRI syntax will not be documented here; see the MRI manuals for more
1526 information. Note in particular that the handling of macros and macro
1527 arguments is somewhat different. The purpose of this option is to permit
1528 assembling existing MRI assembler code using @command{@value{AS}}.
1530 The MRI compatibility is not complete. Certain operations of the MRI assembler
1531 depend upon its object file format, and can not be supported using other object
1532 file formats. Supporting these would require enhancing each object file format
1533 individually. These are:
1536 @item global symbols in common section
1538 The m68k MRI assembler supports common sections which are merged by the linker.
1539 Other object file formats do not support this. @command{@value{AS}} handles
1540 common sections by treating them as a single common symbol. It permits local
1541 symbols to be defined within a common section, but it can not support global
1542 symbols, since it has no way to describe them.
1544 @item complex relocations
1546 The MRI assemblers support relocations against a negated section address, and
1547 relocations which combine the start addresses of two or more sections. These
1548 are not support by other object file formats.
1550 @item @code{END} pseudo-op specifying start address
1552 The MRI @code{END} pseudo-op permits the specification of a start address.
1553 This is not supported by other object file formats. The start address may
1554 instead be specified using the @option{-e} option to the linker, or in a linker
1557 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1559 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1560 name to the output file. This is not supported by other object file formats.
1562 @item @code{ORG} pseudo-op
1564 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1565 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1566 which changes the location within the current section. Absolute sections are
1567 not supported by other object file formats. The address of a section may be
1568 assigned within a linker script.
1571 There are some other features of the MRI assembler which are not supported by
1572 @command{@value{AS}}, typically either because they are difficult or because they
1573 seem of little consequence. Some of these may be supported in future releases.
1577 @item EBCDIC strings
1579 EBCDIC strings are not supported.
1581 @item packed binary coded decimal
1583 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1584 and @code{DCB.P} pseudo-ops are not supported.
1586 @item @code{FEQU} pseudo-op
1588 The m68k @code{FEQU} pseudo-op is not supported.
1590 @item @code{NOOBJ} pseudo-op
1592 The m68k @code{NOOBJ} pseudo-op is not supported.
1594 @item @code{OPT} branch control options
1596 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1597 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1598 relaxes all branches, whether forward or backward, to an appropriate size, so
1599 these options serve no purpose.
1601 @item @code{OPT} list control options
1603 The following m68k @code{OPT} list control options are ignored: @code{C},
1604 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1605 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1607 @item other @code{OPT} options
1609 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1610 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1612 @item @code{OPT} @code{D} option is default
1614 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1615 @code{OPT NOD} may be used to turn it off.
1617 @item @code{XREF} pseudo-op.
1619 The m68k @code{XREF} pseudo-op is ignored.
1621 @item @code{.debug} pseudo-op
1623 The i960 @code{.debug} pseudo-op is not supported.
1625 @item @code{.extended} pseudo-op
1627 The i960 @code{.extended} pseudo-op is not supported.
1629 @item @code{.list} pseudo-op.
1631 The various options of the i960 @code{.list} pseudo-op are not supported.
1633 @item @code{.optimize} pseudo-op
1635 The i960 @code{.optimize} pseudo-op is not supported.
1637 @item @code{.output} pseudo-op
1639 The i960 @code{.output} pseudo-op is not supported.
1641 @item @code{.setreal} pseudo-op
1643 The i960 @code{.setreal} pseudo-op is not supported.
1648 @section Dependency tracking: @option{--MD}
1651 @cindex dependency tracking
1654 @command{@value{AS}} can generate a dependency file for the file it creates. This
1655 file consists of a single rule suitable for @code{make} describing the
1656 dependencies of the main source file.
1658 The rule is written to the file named in its argument.
1660 This feature is used in the automatic updating of makefiles.
1663 @section Name the Object File: @option{-o}
1666 @cindex naming object file
1667 @cindex object file name
1668 There is always one object file output when you run @command{@value{AS}}. By
1669 default it has the name
1672 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1686 You use this option (which takes exactly one filename) to give the
1687 object file a different name.
1689 Whatever the object file is called, @command{@value{AS}} overwrites any
1690 existing file of the same name.
1693 @section Join Data and Text Sections: @option{-R}
1696 @cindex data and text sections, joining
1697 @cindex text and data sections, joining
1698 @cindex joining text and data sections
1699 @cindex merging text and data sections
1700 @option{-R} tells @command{@value{AS}} to write the object file as if all
1701 data-section data lives in the text section. This is only done at
1702 the very last moment: your binary data are the same, but data
1703 section parts are relocated differently. The data section part of
1704 your object file is zero bytes long because all its bytes are
1705 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1707 When you specify @option{-R} it would be possible to generate shorter
1708 address displacements (because we do not have to cross between text and
1709 data section). We refrain from doing this simply for compatibility with
1710 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1713 When @command{@value{AS}} is configured for COFF output,
1714 this option is only useful if you use sections named @samp{.text} and
1719 @option{-R} is not supported for any of the HPPA targets. Using
1720 @option{-R} generates a warning from @command{@value{AS}}.
1724 @section Display Assembly Statistics: @option{--statistics}
1726 @kindex --statistics
1727 @cindex statistics, about assembly
1728 @cindex time, total for assembly
1729 @cindex space used, maximum for assembly
1730 Use @samp{--statistics} to display two statistics about the resources used by
1731 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1732 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1735 @node traditional-format
1736 @section Compatible output: @option{--traditional-format}
1738 @kindex --traditional-format
1739 For some targets, the output of @command{@value{AS}} is different in some ways
1740 from the output of some existing assembler. This switch requests
1741 @command{@value{AS}} to use the traditional format instead.
1743 For example, it disables the exception frame optimizations which
1744 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1747 @section Announce Version: @option{-v}
1751 @cindex assembler version
1752 @cindex version of assembler
1753 You can find out what version of as is running by including the
1754 option @samp{-v} (which you can also spell as @samp{-version}) on the
1758 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1760 @command{@value{AS}} should never give a warning or error message when
1761 assembling compiler output. But programs written by people often
1762 cause @command{@value{AS}} to give a warning that a particular assumption was
1763 made. All such warnings are directed to the standard error file.
1766 @kindex @samp{--no-warn}
1767 @cindex suppressing warnings
1768 @cindex warnings, suppressing
1769 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1770 This only affects the warning messages: it does not change any particular of
1771 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1774 @kindex @samp{--fatal-warnings}
1775 @cindex errors, caused by warnings
1776 @cindex warnings, causing error
1777 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1778 files that generate warnings to be in error.
1780 @kindex @samp{--warn}
1781 @cindex warnings, switching on
1782 You can switch these options off again by specifying @option{--warn}, which
1783 causes warnings to be output as usual.
1786 @section Generate Object File in Spite of Errors: @option{-Z}
1787 @cindex object file, after errors
1788 @cindex errors, continuing after
1789 After an error message, @command{@value{AS}} normally produces no output. If for
1790 some reason you are interested in object file output even after
1791 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1792 option. If there are any errors, @command{@value{AS}} continues anyways, and
1793 writes an object file after a final warning message of the form @samp{@var{n}
1794 errors, @var{m} warnings, generating bad object file.}
1799 @cindex machine-independent syntax
1800 @cindex syntax, machine-independent
1801 This chapter describes the machine-independent syntax allowed in a
1802 source file. @command{@value{AS}} syntax is similar to what many other
1803 assemblers use; it is inspired by the BSD 4.2
1808 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1812 * Preprocessing:: Preprocessing
1813 * Whitespace:: Whitespace
1814 * Comments:: Comments
1815 * Symbol Intro:: Symbols
1816 * Statements:: Statements
1817 * Constants:: Constants
1821 @section Preprocessing
1823 @cindex preprocessing
1824 The @command{@value{AS}} internal preprocessor:
1826 @cindex whitespace, removed by preprocessor
1828 adjusts and removes extra whitespace. It leaves one space or tab before
1829 the keywords on a line, and turns any other whitespace on the line into
1832 @cindex comments, removed by preprocessor
1834 removes all comments, replacing them with a single space, or an
1835 appropriate number of newlines.
1837 @cindex constants, converted by preprocessor
1839 converts character constants into the appropriate numeric values.
1842 It does not do macro processing, include file handling, or
1843 anything else you may get from your C compiler's preprocessor. You can
1844 do include file processing with the @code{.include} directive
1845 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1846 to get other ``CPP'' style preprocessing, by giving the input file a
1847 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1848 Output, gcc.info, Using GNU CC}.
1850 Excess whitespace, comments, and character constants
1851 cannot be used in the portions of the input text that are not
1854 @cindex turning preprocessing on and off
1855 @cindex preprocessing, turning on and off
1858 If the first line of an input file is @code{#NO_APP} or if you use the
1859 @samp{-f} option, whitespace and comments are not removed from the input file.
1860 Within an input file, you can ask for whitespace and comment removal in
1861 specific portions of the by putting a line that says @code{#APP} before the
1862 text that may contain whitespace or comments, and putting a line that says
1863 @code{#NO_APP} after this text. This feature is mainly intend to support
1864 @code{asm} statements in compilers whose output is otherwise free of comments
1871 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1872 Whitespace is used to separate symbols, and to make programs neater for
1873 people to read. Unless within character constants
1874 (@pxref{Characters,,Character Constants}), any whitespace means the same
1875 as exactly one space.
1881 There are two ways of rendering comments to @command{@value{AS}}. In both
1882 cases the comment is equivalent to one space.
1884 Anything from @samp{/*} through the next @samp{*/} is a comment.
1885 This means you may not nest these comments.
1889 The only way to include a newline ('\n') in a comment
1890 is to use this sort of comment.
1893 /* This sort of comment does not nest. */
1896 @cindex line comment character
1897 Anything from the @dfn{line comment} character to the next newline
1898 is considered a comment and is ignored. The line comment character is
1900 @samp{;} for the AMD 29K family;
1903 @samp{;} on the ARC;
1906 @samp{@@} on the ARM;
1909 @samp{;} for the H8/300 family;
1912 @samp{!} for the H8/500 family;
1915 @samp{;} for the HPPA;
1918 @samp{#} on the i386 and x86-64;
1921 @samp{#} on the i960;
1924 @samp{;} for the PDP-11;
1927 @samp{;} for picoJava;
1930 @samp{;} for Motorola PowerPC;
1933 @samp{!} for the Hitachi SH;
1936 @samp{!} on the SPARC;
1939 @samp{#} on the m32r;
1942 @samp{|} on the 680x0;
1945 @samp{#} on the 68HC11 and 68HC12;
1948 @samp{;} on the M880x0;
1951 @samp{#} on the Vax;
1954 @samp{!} for the Z8000;
1957 @samp{#} on the V850;
1959 see @ref{Machine Dependencies}. @refill
1960 @c FIXME What about i860?
1963 On some machines there are two different line comment characters. One
1964 character only begins a comment if it is the first non-whitespace character on
1965 a line, while the other always begins a comment.
1969 The V850 assembler also supports a double dash as starting a comment that
1970 extends to the end of the line.
1976 @cindex lines starting with @code{#}
1977 @cindex logical line numbers
1978 To be compatible with past assemblers, lines that begin with @samp{#} have a
1979 special interpretation. Following the @samp{#} should be an absolute
1980 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1981 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1982 new logical file name. The rest of the line, if any, should be whitespace.
1984 If the first non-whitespace characters on the line are not numeric,
1985 the line is ignored. (Just like a comment.)
1988 # This is an ordinary comment.
1989 # 42-6 "new_file_name" # New logical file name
1990 # This is logical line # 36.
1992 This feature is deprecated, and may disappear from future versions
1993 of @command{@value{AS}}.
1998 @cindex characters used in symbols
1999 @ifclear SPECIAL-SYMS
2000 A @dfn{symbol} is one or more characters chosen from the set of all
2001 letters (both upper and lower case), digits and the three characters
2007 A @dfn{symbol} is one or more characters chosen from the set of all
2008 letters (both upper and lower case), digits and the three characters
2009 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2015 On most machines, you can also use @code{$} in symbol names; exceptions
2016 are noted in @ref{Machine Dependencies}.
2018 No symbol may begin with a digit. Case is significant.
2019 There is no length limit: all characters are significant. Symbols are
2020 delimited by characters not in that set, or by the beginning of a file
2021 (since the source program must end with a newline, the end of a file is
2022 not a possible symbol delimiter). @xref{Symbols}.
2023 @cindex length of symbols
2028 @cindex statements, structure of
2029 @cindex line separator character
2030 @cindex statement separator character
2032 @ifclear abnormal-separator
2033 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2034 semicolon (@samp{;}). The newline or semicolon is considered part of
2035 the preceding statement. Newlines and semicolons within character
2036 constants are an exception: they do not end statements.
2038 @ifset abnormal-separator
2040 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2041 sign (@samp{@@}). The newline or at sign is considered part of the
2042 preceding statement. Newlines and at signs within character constants
2043 are an exception: they do not end statements.
2046 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2047 point (@samp{!}). The newline or exclamation point is considered part of the
2048 preceding statement. Newlines and exclamation points within character
2049 constants are an exception: they do not end statements.
2052 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2053 H8/300) a dollar sign (@samp{$}); or (for the
2056 (@samp{;}). The newline or separator character is considered part of
2057 the preceding statement. Newlines and separators within character
2058 constants are an exception: they do not end statements.
2063 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2064 separator character. (The line separator is usually @samp{;}, unless
2065 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2066 newline or separator character is considered part of the preceding
2067 statement. Newlines and separators within character constants are an
2068 exception: they do not end statements.
2071 @cindex newline, required at file end
2072 @cindex EOF, newline must precede
2073 It is an error to end any statement with end-of-file: the last
2074 character of any input file should be a newline.@refill
2076 An empty statement is allowed, and may include whitespace. It is ignored.
2078 @cindex instructions and directives
2079 @cindex directives and instructions
2080 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2081 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2083 A statement begins with zero or more labels, optionally followed by a
2084 key symbol which determines what kind of statement it is. The key
2085 symbol determines the syntax of the rest of the statement. If the
2086 symbol begins with a dot @samp{.} then the statement is an assembler
2087 directive: typically valid for any computer. If the symbol begins with
2088 a letter the statement is an assembly language @dfn{instruction}: it
2089 assembles into a machine language instruction.
2091 Different versions of @command{@value{AS}} for different computers
2092 recognize different instructions. In fact, the same symbol may
2093 represent a different instruction in a different computer's assembly
2097 @cindex @code{:} (label)
2098 @cindex label (@code{:})
2099 A label is a symbol immediately followed by a colon (@code{:}).
2100 Whitespace before a label or after a colon is permitted, but you may not
2101 have whitespace between a label's symbol and its colon. @xref{Labels}.
2104 For HPPA targets, labels need not be immediately followed by a colon, but
2105 the definition of a label must begin in column zero. This also implies that
2106 only one label may be defined on each line.
2110 label: .directive followed by something
2111 another_label: # This is an empty statement.
2112 instruction operand_1, operand_2, @dots{}
2119 A constant is a number, written so that its value is known by
2120 inspection, without knowing any context. Like this:
2123 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2124 .ascii "Ring the bell\7" # A string constant.
2125 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2126 .float 0f-314159265358979323846264338327\
2127 95028841971.693993751E-40 # - pi, a flonum.
2132 * Characters:: Character Constants
2133 * Numbers:: Number Constants
2137 @subsection Character Constants
2139 @cindex character constants
2140 @cindex constants, character
2141 There are two kinds of character constants. A @dfn{character} stands
2142 for one character in one byte and its value may be used in
2143 numeric expressions. String constants (properly called string
2144 @emph{literals}) are potentially many bytes and their values may not be
2145 used in arithmetic expressions.
2149 * Chars:: Characters
2153 @subsubsection Strings
2155 @cindex string constants
2156 @cindex constants, string
2157 A @dfn{string} is written between double-quotes. It may contain
2158 double-quotes or null characters. The way to get special characters
2159 into a string is to @dfn{escape} these characters: precede them with
2160 a backslash @samp{\} character. For example @samp{\\} represents
2161 one backslash: the first @code{\} is an escape which tells
2162 @command{@value{AS}} to interpret the second character literally as a backslash
2163 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2164 escape character). The complete list of escapes follows.
2166 @cindex escape codes, character
2167 @cindex character escape codes
2170 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2172 @cindex @code{\b} (backspace character)
2173 @cindex backspace (@code{\b})
2175 Mnemonic for backspace; for ASCII this is octal code 010.
2178 @c Mnemonic for EOText; for ASCII this is octal code 004.
2180 @cindex @code{\f} (formfeed character)
2181 @cindex formfeed (@code{\f})
2183 Mnemonic for FormFeed; for ASCII this is octal code 014.
2185 @cindex @code{\n} (newline character)
2186 @cindex newline (@code{\n})
2188 Mnemonic for newline; for ASCII this is octal code 012.
2191 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2193 @cindex @code{\r} (carriage return character)
2194 @cindex carriage return (@code{\r})
2196 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2199 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2200 @c other assemblers.
2202 @cindex @code{\t} (tab)
2203 @cindex tab (@code{\t})
2205 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2208 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2209 @c @item \x @var{digit} @var{digit} @var{digit}
2210 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2212 @cindex @code{\@var{ddd}} (octal character code)
2213 @cindex octal character code (@code{\@var{ddd}})
2214 @item \ @var{digit} @var{digit} @var{digit}
2215 An octal character code. The numeric code is 3 octal digits.
2216 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2217 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2219 @cindex @code{\@var{xd...}} (hex character code)
2220 @cindex hex character code (@code{\@var{xd...}})
2221 @item \@code{x} @var{hex-digits...}
2222 A hex character code. All trailing hex digits are combined. Either upper or
2223 lower case @code{x} works.
2225 @cindex @code{\\} (@samp{\} character)
2226 @cindex backslash (@code{\\})
2228 Represents one @samp{\} character.
2231 @c Represents one @samp{'} (accent acute) character.
2232 @c This is needed in single character literals
2233 @c (@xref{Characters,,Character Constants}.) to represent
2236 @cindex @code{\"} (doublequote character)
2237 @cindex doublequote (@code{\"})
2239 Represents one @samp{"} character. Needed in strings to represent
2240 this character, because an unescaped @samp{"} would end the string.
2242 @item \ @var{anything-else}
2243 Any other character when escaped by @kbd{\} gives a warning, but
2244 assembles as if the @samp{\} was not present. The idea is that if
2245 you used an escape sequence you clearly didn't want the literal
2246 interpretation of the following character. However @command{@value{AS}} has no
2247 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2248 code and warns you of the fact.
2251 Which characters are escapable, and what those escapes represent,
2252 varies widely among assemblers. The current set is what we think
2253 the BSD 4.2 assembler recognizes, and is a subset of what most C
2254 compilers recognize. If you are in doubt, do not use an escape
2258 @subsubsection Characters
2260 @cindex single character constant
2261 @cindex character, single
2262 @cindex constant, single character
2263 A single character may be written as a single quote immediately
2264 followed by that character. The same escapes apply to characters as
2265 to strings. So if you want to write the character backslash, you
2266 must write @kbd{'\\} where the first @code{\} escapes the second
2267 @code{\}. As you can see, the quote is an acute accent, not a
2268 grave accent. A newline
2270 @ifclear abnormal-separator
2271 (or semicolon @samp{;})
2273 @ifset abnormal-separator
2275 (or at sign @samp{@@})
2278 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2284 immediately following an acute accent is taken as a literal character
2285 and does not count as the end of a statement. The value of a character
2286 constant in a numeric expression is the machine's byte-wide code for
2287 that character. @command{@value{AS}} assumes your character code is ASCII:
2288 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2291 @subsection Number Constants
2293 @cindex constants, number
2294 @cindex number constants
2295 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2296 are stored in the target machine. @emph{Integers} are numbers that
2297 would fit into an @code{int} in the C language. @emph{Bignums} are
2298 integers, but they are stored in more than 32 bits. @emph{Flonums}
2299 are floating point numbers, described below.
2302 * Integers:: Integers
2307 * Bit Fields:: Bit Fields
2313 @subsubsection Integers
2315 @cindex constants, integer
2317 @cindex binary integers
2318 @cindex integers, binary
2319 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2320 the binary digits @samp{01}.
2322 @cindex octal integers
2323 @cindex integers, octal
2324 An octal integer is @samp{0} followed by zero or more of the octal
2325 digits (@samp{01234567}).
2327 @cindex decimal integers
2328 @cindex integers, decimal
2329 A decimal integer starts with a non-zero digit followed by zero or
2330 more digits (@samp{0123456789}).
2332 @cindex hexadecimal integers
2333 @cindex integers, hexadecimal
2334 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2335 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2337 Integers have the usual values. To denote a negative integer, use
2338 the prefix operator @samp{-} discussed under expressions
2339 (@pxref{Prefix Ops,,Prefix Operators}).
2342 @subsubsection Bignums
2345 @cindex constants, bignum
2346 A @dfn{bignum} has the same syntax and semantics as an integer
2347 except that the number (or its negative) takes more than 32 bits to
2348 represent in binary. The distinction is made because in some places
2349 integers are permitted while bignums are not.
2352 @subsubsection Flonums
2354 @cindex floating point numbers
2355 @cindex constants, floating point
2357 @cindex precision, floating point
2358 A @dfn{flonum} represents a floating point number. The translation is
2359 indirect: a decimal floating point number from the text is converted by
2360 @command{@value{AS}} to a generic binary floating point number of more than
2361 sufficient precision. This generic floating point number is converted
2362 to a particular computer's floating point format (or formats) by a
2363 portion of @command{@value{AS}} specialized to that computer.
2365 A flonum is written by writing (in order)
2370 (@samp{0} is optional on the HPPA.)
2374 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2376 @kbd{e} is recommended. Case is not important.
2378 @c FIXME: verify if flonum syntax really this vague for most cases
2379 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2380 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2383 On the H8/300, H8/500,
2385 and AMD 29K architectures, the letter must be
2386 one of the letters @samp{DFPRSX} (in upper or lower case).
2388 On the ARC, the letter must be one of the letters @samp{DFRS}
2389 (in upper or lower case).
2391 On the Intel 960 architecture, the letter must be
2392 one of the letters @samp{DFT} (in upper or lower case).
2394 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2398 One of the letters @samp{DFPRSX} (in upper or lower case).
2401 One of the letters @samp{DFRS} (in upper or lower case).
2404 One of the letters @samp{DFPRSX} (in upper or lower case).
2407 The letter @samp{E} (upper case only).
2410 One of the letters @samp{DFT} (in upper or lower case).
2415 An optional sign: either @samp{+} or @samp{-}.
2418 An optional @dfn{integer part}: zero or more decimal digits.
2421 An optional @dfn{fractional part}: @samp{.} followed by zero
2422 or more decimal digits.
2425 An optional exponent, consisting of:
2429 An @samp{E} or @samp{e}.
2430 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2431 @c principle this can perfectly well be different on different targets.
2433 Optional sign: either @samp{+} or @samp{-}.
2435 One or more decimal digits.
2440 At least one of the integer part or the fractional part must be
2441 present. The floating point number has the usual base-10 value.
2443 @command{@value{AS}} does all processing using integers. Flonums are computed
2444 independently of any floating point hardware in the computer running
2445 @command{@value{AS}}.
2449 @c Bit fields are written as a general facility but are also controlled
2450 @c by a conditional-compilation flag---which is as of now (21mar91)
2451 @c turned on only by the i960 config of GAS.
2453 @subsubsection Bit Fields
2456 @cindex constants, bit field
2457 You can also define numeric constants as @dfn{bit fields}.
2458 specify two numbers separated by a colon---
2460 @var{mask}:@var{value}
2463 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2466 The resulting number is then packed
2468 @c this conditional paren in case bit fields turned on elsewhere than 960
2469 (in host-dependent byte order)
2471 into a field whose width depends on which assembler directive has the
2472 bit-field as its argument. Overflow (a result from the bitwise and
2473 requiring more binary digits to represent) is not an error; instead,
2474 more constants are generated, of the specified width, beginning with the
2475 least significant digits.@refill
2477 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2478 @code{.short}, and @code{.word} accept bit-field arguments.
2483 @chapter Sections and Relocation
2488 * Secs Background:: Background
2489 * Ld Sections:: Linker Sections
2490 * As Sections:: Assembler Internal Sections
2491 * Sub-Sections:: Sub-Sections
2495 @node Secs Background
2498 Roughly, a section is a range of addresses, with no gaps; all data
2499 ``in'' those addresses is treated the same for some particular purpose.
2500 For example there may be a ``read only'' section.
2502 @cindex linker, and assembler
2503 @cindex assembler, and linker
2504 The linker @code{@value{LD}} reads many object files (partial programs) and
2505 combines their contents to form a runnable program. When @command{@value{AS}}
2506 emits an object file, the partial program is assumed to start at address 0.
2507 @code{@value{LD}} assigns the final addresses for the partial program, so that
2508 different partial programs do not overlap. This is actually an
2509 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2512 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2513 addresses. These blocks slide to their run-time addresses as rigid
2514 units; their length does not change and neither does the order of bytes
2515 within them. Such a rigid unit is called a @emph{section}. Assigning
2516 run-time addresses to sections is called @dfn{relocation}. It includes
2517 the task of adjusting mentions of object-file addresses so they refer to
2518 the proper run-time addresses.
2520 For the H8/300 and H8/500,
2521 and for the Hitachi SH,
2522 @command{@value{AS}} pads sections if needed to
2523 ensure they end on a word (sixteen bit) boundary.
2526 @cindex standard assembler sections
2527 An object file written by @command{@value{AS}} has at least three sections, any
2528 of which may be empty. These are named @dfn{text}, @dfn{data} and
2533 When it generates COFF output,
2535 @command{@value{AS}} can also generate whatever other named sections you specify
2536 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2537 If you do not use any directives that place output in the @samp{.text}
2538 or @samp{.data} sections, these sections still exist, but are empty.
2543 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2545 @command{@value{AS}} can also generate whatever other named sections you
2546 specify using the @samp{.space} and @samp{.subspace} directives. See
2547 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2548 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2549 assembler directives.
2552 Additionally, @command{@value{AS}} uses different names for the standard
2553 text, data, and bss sections when generating SOM output. Program text
2554 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2555 BSS into @samp{$BSS$}.
2559 Within the object file, the text section starts at address @code{0}, the
2560 data section follows, and the bss section follows the data section.
2563 When generating either SOM or ELF output files on the HPPA, the text
2564 section starts at address @code{0}, the data section at address
2565 @code{0x4000000}, and the bss section follows the data section.
2568 To let @code{@value{LD}} know which data changes when the sections are
2569 relocated, and how to change that data, @command{@value{AS}} also writes to the
2570 object file details of the relocation needed. To perform relocation
2571 @code{@value{LD}} must know, each time an address in the object
2575 Where in the object file is the beginning of this reference to
2578 How long (in bytes) is this reference?
2580 Which section does the address refer to? What is the numeric value of
2582 (@var{address}) @minus{} (@var{start-address of section})?
2585 Is the reference to an address ``Program-Counter relative''?
2588 @cindex addresses, format of
2589 @cindex section-relative addressing
2590 In fact, every address @command{@value{AS}} ever uses is expressed as
2592 (@var{section}) + (@var{offset into section})
2595 Further, most expressions @command{@value{AS}} computes have this section-relative
2598 (For some object formats, such as SOM for the HPPA, some expressions are
2599 symbol-relative instead.)
2602 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2603 @var{N} into section @var{secname}.''
2605 Apart from text, data and bss sections you need to know about the
2606 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2607 addresses in the absolute section remain unchanged. For example, address
2608 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2609 @code{@value{LD}}. Although the linker never arranges two partial programs'
2610 data sections with overlapping addresses after linking, @emph{by definition}
2611 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2612 part of a program is always the same address when the program is running as
2613 address @code{@{absolute@ 239@}} in any other part of the program.
2615 The idea of sections is extended to the @dfn{undefined} section. Any
2616 address whose section is unknown at assembly time is by definition
2617 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2618 Since numbers are always defined, the only way to generate an undefined
2619 address is to mention an undefined symbol. A reference to a named
2620 common block would be such a symbol: its value is unknown at assembly
2621 time so it has section @emph{undefined}.
2623 By analogy the word @emph{section} is used to describe groups of sections in
2624 the linked program. @code{@value{LD}} puts all partial programs' text
2625 sections in contiguous addresses in the linked program. It is
2626 customary to refer to the @emph{text section} of a program, meaning all
2627 the addresses of all partial programs' text sections. Likewise for
2628 data and bss sections.
2630 Some sections are manipulated by @code{@value{LD}}; others are invented for
2631 use of @command{@value{AS}} and have no meaning except during assembly.
2634 @section Linker Sections
2635 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2640 @cindex named sections
2641 @cindex sections, named
2642 @item named sections
2645 @cindex text section
2646 @cindex data section
2650 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2651 separate but equal sections. Anything you can say of one section is
2654 When the program is running, however, it is
2655 customary for the text section to be unalterable. The
2656 text section is often shared among processes: it contains
2657 instructions, constants and the like. The data section of a running
2658 program is usually alterable: for example, C variables would be stored
2659 in the data section.
2664 This section contains zeroed bytes when your program begins running. It
2665 is used to hold uninitialized variables or common storage. The length of
2666 each partial program's bss section is important, but because it starts
2667 out containing zeroed bytes there is no need to store explicit zero
2668 bytes in the object file. The bss section was invented to eliminate
2669 those explicit zeros from object files.
2671 @cindex absolute section
2672 @item absolute section
2673 Address 0 of this section is always ``relocated'' to runtime address 0.
2674 This is useful if you want to refer to an address that @code{@value{LD}} must
2675 not change when relocating. In this sense we speak of absolute
2676 addresses being ``unrelocatable'': they do not change during relocation.
2678 @cindex undefined section
2679 @item undefined section
2680 This ``section'' is a catch-all for address references to objects not in
2681 the preceding sections.
2682 @c FIXME: ref to some other doc on obj-file formats could go here.
2685 @cindex relocation example
2686 An idealized example of three relocatable sections follows.
2688 The example uses the traditional section names @samp{.text} and @samp{.data}.
2690 Memory addresses are on the horizontal axis.
2694 @c END TEXI2ROFF-KILL
2697 partial program # 1: |ttttt|dddd|00|
2704 partial program # 2: |TTT|DDD|000|
2707 +--+---+-----+--+----+---+-----+~~
2708 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2709 +--+---+-----+--+----+---+-----+~~
2711 addresses: 0 @dots{}
2718 \line{\it Partial program \#1: \hfil}
2719 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2720 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2722 \line{\it Partial program \#2: \hfil}
2723 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2724 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2726 \line{\it linked program: \hfil}
2727 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2728 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2729 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2730 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2732 \line{\it addresses: \hfil}
2736 @c END TEXI2ROFF-KILL
2739 @section Assembler Internal Sections
2741 @cindex internal assembler sections
2742 @cindex sections in messages, internal
2743 These sections are meant only for the internal use of @command{@value{AS}}. They
2744 have no meaning at run-time. You do not really need to know about these
2745 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2746 warning messages, so it might be helpful to have an idea of their
2747 meanings to @command{@value{AS}}. These sections are used to permit the
2748 value of every expression in your assembly language program to be a
2749 section-relative address.
2752 @cindex assembler internal logic error
2753 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2754 An internal assembler logic error has been found. This means there is a
2755 bug in the assembler.
2757 @cindex expr (internal section)
2759 The assembler stores complex expression internally as combinations of
2760 symbols. When it needs to represent an expression as a symbol, it puts
2761 it in the expr section.
2763 @c FIXME item transfer[t] vector preload
2764 @c FIXME item transfer[t] vector postload
2765 @c FIXME item register
2769 @section Sub-Sections
2771 @cindex numbered subsections
2772 @cindex grouping data
2778 fall into two sections: text and data.
2780 You may have separate groups of
2782 data in named sections
2786 data in named sections
2792 that you want to end up near to each other in the object file, even though they
2793 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2794 use @dfn{subsections} for this purpose. Within each section, there can be
2795 numbered subsections with values from 0 to 8192. Objects assembled into the
2796 same subsection go into the object file together with other objects in the same
2797 subsection. For example, a compiler might want to store constants in the text
2798 section, but might not want to have them interspersed with the program being
2799 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2800 section of code being output, and a @samp{.text 1} before each group of
2801 constants being output.
2803 Subsections are optional. If you do not use subsections, everything
2804 goes in subsection number zero.
2807 Each subsection is zero-padded up to a multiple of four bytes.
2808 (Subsections may be padded a different amount on different flavors
2809 of @command{@value{AS}}.)
2813 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2814 boundary (two bytes).
2815 The same is true on the Hitachi SH.
2818 @c FIXME section padding (alignment)?
2819 @c Rich Pixley says padding here depends on target obj code format; that
2820 @c doesn't seem particularly useful to say without further elaboration,
2821 @c so for now I say nothing about it. If this is a generic BFD issue,
2822 @c these paragraphs might need to vanish from this manual, and be
2823 @c discussed in BFD chapter of binutils (or some such).
2826 On the AMD 29K family, no particular padding is added to section or
2827 subsection sizes; @value{AS} forces no alignment on this platform.
2831 Subsections appear in your object file in numeric order, lowest numbered
2832 to highest. (All this to be compatible with other people's assemblers.)
2833 The object file contains no representation of subsections; @code{@value{LD}} and
2834 other programs that manipulate object files see no trace of them.
2835 They just see all your text subsections as a text section, and all your
2836 data subsections as a data section.
2838 To specify which subsection you want subsequent statements assembled
2839 into, use a numeric argument to specify it, in a @samp{.text
2840 @var{expression}} or a @samp{.data @var{expression}} statement.
2843 When generating COFF output, you
2848 can also use an extra subsection
2849 argument with arbitrary named sections: @samp{.section @var{name},
2852 @var{Expression} should be an absolute expression.
2853 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2854 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2855 begins in @code{text 0}. For instance:
2857 .text 0 # The default subsection is text 0 anyway.
2858 .ascii "This lives in the first text subsection. *"
2860 .ascii "But this lives in the second text subsection."
2862 .ascii "This lives in the data section,"
2863 .ascii "in the first data subsection."
2865 .ascii "This lives in the first text section,"
2866 .ascii "immediately following the asterisk (*)."
2869 Each section has a @dfn{location counter} incremented by one for every byte
2870 assembled into that section. Because subsections are merely a convenience
2871 restricted to @command{@value{AS}} there is no concept of a subsection location
2872 counter. There is no way to directly manipulate a location counter---but the
2873 @code{.align} directive changes it, and any label definition captures its
2874 current value. The location counter of the section where statements are being
2875 assembled is said to be the @dfn{active} location counter.
2878 @section bss Section
2881 @cindex common variable storage
2882 The bss section is used for local common variable storage.
2883 You may allocate address space in the bss section, but you may
2884 not dictate data to load into it before your program executes. When
2885 your program starts running, all the contents of the bss
2886 section are zeroed bytes.
2888 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2889 @ref{Lcomm,,@code{.lcomm}}.
2891 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2892 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2895 When assembling for a target which supports multiple sections, such as ELF or
2896 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2897 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2898 section. Typically the section will only contain symbol definitions and
2899 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2906 Symbols are a central concept: the programmer uses symbols to name
2907 things, the linker uses symbols to link, and the debugger uses symbols
2911 @cindex debuggers, and symbol order
2912 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2913 the same order they were declared. This may break some debuggers.
2918 * Setting Symbols:: Giving Symbols Other Values
2919 * Symbol Names:: Symbol Names
2920 * Dot:: The Special Dot Symbol
2921 * Symbol Attributes:: Symbol Attributes
2928 A @dfn{label} is written as a symbol immediately followed by a colon
2929 @samp{:}. The symbol then represents the current value of the
2930 active location counter, and is, for example, a suitable instruction
2931 operand. You are warned if you use the same symbol to represent two
2932 different locations: the first definition overrides any other
2936 On the HPPA, the usual form for a label need not be immediately followed by a
2937 colon, but instead must start in column zero. Only one label may be defined on
2938 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2939 provides a special directive @code{.label} for defining labels more flexibly.
2942 @node Setting Symbols
2943 @section Giving Symbols Other Values
2945 @cindex assigning values to symbols
2946 @cindex symbol values, assigning
2947 A symbol can be given an arbitrary value by writing a symbol, followed
2948 by an equals sign @samp{=}, followed by an expression
2949 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2950 directive. @xref{Set,,@code{.set}}.
2953 @section Symbol Names
2955 @cindex symbol names
2956 @cindex names, symbol
2957 @ifclear SPECIAL-SYMS
2958 Symbol names begin with a letter or with one of @samp{._}. On most
2959 machines, you can also use @code{$} in symbol names; exceptions are
2960 noted in @ref{Machine Dependencies}. That character may be followed by any
2961 string of digits, letters, dollar signs (unless otherwise noted in
2962 @ref{Machine Dependencies}), and underscores.
2965 For the AMD 29K family, @samp{?} is also allowed in the
2966 body of a symbol name, though not at its beginning.
2971 Symbol names begin with a letter or with one of @samp{._}. On the
2973 H8/500, you can also use @code{$} in symbol names. That character may
2974 be followed by any string of digits, letters, dollar signs (save on the
2975 H8/300), and underscores.
2979 Case of letters is significant: @code{foo} is a different symbol name
2982 Each symbol has exactly one name. Each name in an assembly language program
2983 refers to exactly one symbol. You may use that symbol name any number of times
2986 @subheading Local Symbol Names
2988 @cindex local symbol names
2989 @cindex symbol names, local
2990 @cindex temporary symbol names
2991 @cindex symbol names, temporary
2992 Local symbols help compilers and programmers use names temporarily.
2993 They create symbols which are guaranteed to be unique over the entire scope of
2994 the input source code and which can be referred to by a simple notation.
2995 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
2996 represents any positive integer). To refer to the most recent previous
2997 definition of that symbol write @samp{@b{N}b}, using the same number as when
2998 you defined the label. To refer to the next definition of a local label, write
2999 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3002 There is no restriction on how you can use these labels, and you can reuse them
3003 too. So that it is possible to repeatedly define the same local label (using
3004 the same number @samp{@b{N}}), although you can only refer to the most recently
3005 defined local label of that number (for a backwards reference) or the next
3006 definition of a specific local label for a forward reference. It is also worth
3007 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3008 implemented in a slightly more efficient manner than the others.
3019 Which is the equivalent of:
3022 label_1: branch label_3
3023 label_2: branch label_1
3024 label_3: branch label_4
3025 label_4: branch label_3
3028 Local symbol names are only a notational device. They are immediately
3029 transformed into more conventional symbol names before the assembler uses them.
3030 The symbol names stored in the symbol table, appearing in error messages and
3031 optionally emitted to the object file. The names are constructed using these
3036 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3037 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3038 used for symbols you are never intended to see. If you use the
3039 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3040 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3041 you may use them in debugging.
3044 This is the number that was used in the local label definition. So if the
3045 label is written @samp{55:} then the number is @samp{55}.
3048 This unusual character is included so you do not accidentally invent a symbol
3049 of the same name. The character has ASCII value of @samp{\002} (control-B).
3051 @item @emph{ordinal number}
3052 This is a serial number to keep the labels distinct. The first definition of
3053 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3054 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3055 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3058 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3059 @code{3:} is named @code{L3@kbd{C-B}44}.
3061 @subheading Dollar Local Labels
3062 @cindex dollar local symbols
3064 @code{@value{AS}} also supports an even more local form of local labels called
3065 dollar labels. These labels go out of scope (ie they become undefined) as soon
3066 as a non-local label is defined. Thus they remain valid for only a small
3067 region of the input source code. Normal local labels, by contrast, remain in
3068 scope for the entire file, or until they are redefined by another occurrence of
3069 the same local label.
3071 Dollar labels are defined in exactly the same way as ordinary local labels,
3072 except that instead of being terminated by a colon, they are terminated by a
3073 dollar sign. eg @samp{@b{55$}}.
3075 They can also be distinguished from ordinary local labels by their transformed
3076 name which uses ASCII character @samp{\001} (control-A) as the magic character
3077 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3078 is named @samp{L6@kbd{C-A}5}.
3081 @section The Special Dot Symbol
3083 @cindex dot (symbol)
3084 @cindex @code{.} (symbol)
3085 @cindex current address
3086 @cindex location counter
3087 The special symbol @samp{.} refers to the current address that
3088 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3089 .long .} defines @code{melvin} to contain its own address.
3090 Assigning a value to @code{.} is treated the same as a @code{.org}
3091 directive. Thus, the expression @samp{.=.+4} is the same as saying
3092 @ifclear no-space-dir
3101 @node Symbol Attributes
3102 @section Symbol Attributes
3104 @cindex symbol attributes
3105 @cindex attributes, symbol
3106 Every symbol has, as well as its name, the attributes ``Value'' and
3107 ``Type''. Depending on output format, symbols can also have auxiliary
3110 The detailed definitions are in @file{a.out.h}.
3113 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3114 all these attributes, and probably won't warn you. This makes the
3115 symbol an externally defined symbol, which is generally what you
3119 * Symbol Value:: Value
3120 * Symbol Type:: Type
3123 * a.out Symbols:: Symbol Attributes: @code{a.out}
3127 * a.out Symbols:: Symbol Attributes: @code{a.out}
3130 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3135 * COFF Symbols:: Symbol Attributes for COFF
3138 * SOM Symbols:: Symbol Attributes for SOM
3145 @cindex value of a symbol
3146 @cindex symbol value
3147 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3148 location in the text, data, bss or absolute sections the value is the
3149 number of addresses from the start of that section to the label.
3150 Naturally for text, data and bss sections the value of a symbol changes
3151 as @code{@value{LD}} changes section base addresses during linking. Absolute
3152 symbols' values do not change during linking: that is why they are
3155 The value of an undefined symbol is treated in a special way. If it is
3156 0 then the symbol is not defined in this assembler source file, and
3157 @code{@value{LD}} tries to determine its value from other files linked into the
3158 same program. You make this kind of symbol simply by mentioning a symbol
3159 name without defining it. A non-zero value represents a @code{.comm}
3160 common declaration. The value is how much common storage to reserve, in
3161 bytes (addresses). The symbol refers to the first address of the
3167 @cindex type of a symbol
3169 The type attribute of a symbol contains relocation (section)
3170 information, any flag settings indicating that a symbol is external, and
3171 (optionally), other information for linkers and debuggers. The exact
3172 format depends on the object-code output format in use.
3177 @c The following avoids a "widow" subsection title. @group would be
3178 @c better if it were available outside examples.
3181 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3183 @cindex @code{b.out} symbol attributes
3184 @cindex symbol attributes, @code{b.out}
3185 These symbol attributes appear only when @command{@value{AS}} is configured for
3186 one of the Berkeley-descended object output formats---@code{a.out} or
3192 @subsection Symbol Attributes: @code{a.out}
3194 @cindex @code{a.out} symbol attributes
3195 @cindex symbol attributes, @code{a.out}
3201 @subsection Symbol Attributes: @code{a.out}
3203 @cindex @code{a.out} symbol attributes
3204 @cindex symbol attributes, @code{a.out}
3208 * Symbol Desc:: Descriptor
3209 * Symbol Other:: Other
3213 @subsubsection Descriptor
3215 @cindex descriptor, of @code{a.out} symbol
3216 This is an arbitrary 16-bit value. You may establish a symbol's
3217 descriptor value by using a @code{.desc} statement
3218 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3219 @command{@value{AS}}.
3222 @subsubsection Other
3224 @cindex other attribute, of @code{a.out} symbol
3225 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3230 @subsection Symbol Attributes for COFF
3232 @cindex COFF symbol attributes
3233 @cindex symbol attributes, COFF
3235 The COFF format supports a multitude of auxiliary symbol attributes;
3236 like the primary symbol attributes, they are set between @code{.def} and
3237 @code{.endef} directives.
3239 @subsubsection Primary Attributes
3241 @cindex primary attributes, COFF symbols
3242 The symbol name is set with @code{.def}; the value and type,
3243 respectively, with @code{.val} and @code{.type}.
3245 @subsubsection Auxiliary Attributes
3247 @cindex auxiliary attributes, COFF symbols
3248 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3249 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3250 information for COFF.
3255 @subsection Symbol Attributes for SOM
3257 @cindex SOM symbol attributes
3258 @cindex symbol attributes, SOM
3260 The SOM format for the HPPA supports a multitude of symbol attributes set with
3261 the @code{.EXPORT} and @code{.IMPORT} directives.
3263 The attributes are described in @cite{HP9000 Series 800 Assembly
3264 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3265 @code{EXPORT} assembler directive documentation.
3269 @chapter Expressions
3273 @cindex numeric values
3274 An @dfn{expression} specifies an address or numeric value.
3275 Whitespace may precede and/or follow an expression.
3277 The result of an expression must be an absolute number, or else an offset into
3278 a particular section. If an expression is not absolute, and there is not
3279 enough information when @command{@value{AS}} sees the expression to know its
3280 section, a second pass over the source program might be necessary to interpret
3281 the expression---but the second pass is currently not implemented.
3282 @command{@value{AS}} aborts with an error message in this situation.
3285 * Empty Exprs:: Empty Expressions
3286 * Integer Exprs:: Integer Expressions
3290 @section Empty Expressions
3292 @cindex empty expressions
3293 @cindex expressions, empty
3294 An empty expression has no value: it is just whitespace or null.
3295 Wherever an absolute expression is required, you may omit the
3296 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3297 is compatible with other assemblers.
3300 @section Integer Expressions
3302 @cindex integer expressions
3303 @cindex expressions, integer
3304 An @dfn{integer expression} is one or more @emph{arguments} delimited
3305 by @emph{operators}.
3308 * Arguments:: Arguments
3309 * Operators:: Operators
3310 * Prefix Ops:: Prefix Operators
3311 * Infix Ops:: Infix Operators
3315 @subsection Arguments
3317 @cindex expression arguments
3318 @cindex arguments in expressions
3319 @cindex operands in expressions
3320 @cindex arithmetic operands
3321 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3322 contexts arguments are sometimes called ``arithmetic operands''. In
3323 this manual, to avoid confusing them with the ``instruction operands'' of
3324 the machine language, we use the term ``argument'' to refer to parts of
3325 expressions only, reserving the word ``operand'' to refer only to machine
3326 instruction operands.
3328 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3329 @var{section} is one of text, data, bss, absolute,
3330 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3333 Numbers are usually integers.
3335 A number can be a flonum or bignum. In this case, you are warned
3336 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3337 these 32 bits are an integer. You may write integer-manipulating
3338 instructions that act on exotic constants, compatible with other
3341 @cindex subexpressions
3342 Subexpressions are a left parenthesis @samp{(} followed by an integer
3343 expression, followed by a right parenthesis @samp{)}; or a prefix
3344 operator followed by an argument.
3347 @subsection Operators
3349 @cindex operators, in expressions
3350 @cindex arithmetic functions
3351 @cindex functions, in expressions
3352 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3353 operators are followed by an argument. Infix operators appear
3354 between their arguments. Operators may be preceded and/or followed by
3358 @subsection Prefix Operator
3360 @cindex prefix operators
3361 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3362 one argument, which must be absolute.
3364 @c the tex/end tex stuff surrounding this small table is meant to make
3365 @c it align, on the printed page, with the similar table in the next
3366 @c section (which is inside an enumerate).
3368 \global\advance\leftskip by \itemindent
3373 @dfn{Negation}. Two's complement negation.
3375 @dfn{Complementation}. Bitwise not.
3379 \global\advance\leftskip by -\itemindent
3383 @subsection Infix Operators
3385 @cindex infix operators
3386 @cindex operators, permitted arguments
3387 @dfn{Infix operators} take two arguments, one on either side. Operators
3388 have precedence, but operations with equal precedence are performed left
3389 to right. Apart from @code{+} or @option{-}, both arguments must be
3390 absolute, and the result is absolute.
3393 @cindex operator precedence
3394 @cindex precedence of operators
3401 @dfn{Multiplication}.
3404 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3411 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3415 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3419 Intermediate precedence
3424 @dfn{Bitwise Inclusive Or}.
3430 @dfn{Bitwise Exclusive Or}.
3433 @dfn{Bitwise Or Not}.
3440 @cindex addition, permitted arguments
3441 @cindex plus, permitted arguments
3442 @cindex arguments for addition
3444 @dfn{Addition}. If either argument is absolute, the result has the section of
3445 the other argument. You may not add together arguments from different
3448 @cindex subtraction, permitted arguments
3449 @cindex minus, permitted arguments
3450 @cindex arguments for subtraction
3452 @dfn{Subtraction}. If the right argument is absolute, the
3453 result has the section of the left argument.
3454 If both arguments are in the same section, the result is absolute.
3455 You may not subtract arguments from different sections.
3456 @c FIXME is there still something useful to say about undefined - undefined ?
3458 @cindex comparison expressions
3459 @cindex expressions, comparison
3463 @dfn{Is Not Equal To}
3467 @dfn{Is Greater Than}
3469 @dfn{Is Greater Than Or Equal To}
3471 @dfn{Is Less Than Or Equal To}
3473 The comparison operators can be used as infix operators. A true results has a
3474 value of -1 whereas a false result has a value of 0. Note, these operators
3475 perform signed comparisons.
3478 @item Lowest Precedence
3487 These two logical operations can be used to combine the results of sub
3488 expressions. Note, unlike the comparison operators a true result returns a
3489 value of 1 but a false results does still return 0. Also note that the logical
3490 or operator has a slightly lower precedence than logical and.
3495 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3496 address; you can only have a defined section in one of the two arguments.
3499 @chapter Assembler Directives
3501 @cindex directives, machine independent
3502 @cindex pseudo-ops, machine independent
3503 @cindex machine independent directives
3504 All assembler directives have names that begin with a period (@samp{.}).
3505 The rest of the name is letters, usually in lower case.
3507 This chapter discusses directives that are available regardless of the
3508 target machine configuration for the @sc{gnu} assembler.
3510 Some machine configurations provide additional directives.
3511 @xref{Machine Dependencies}.
3514 @ifset machine-directives
3515 @xref{Machine Dependencies} for additional directives.
3520 * Abort:: @code{.abort}
3522 * ABORT:: @code{.ABORT}
3525 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3526 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3527 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3528 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3529 * Byte:: @code{.byte @var{expressions}}
3530 * Comm:: @code{.comm @var{symbol} , @var{length} }
3531 * Data:: @code{.data @var{subsection}}
3533 * Def:: @code{.def @var{name}}
3536 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3542 * Double:: @code{.double @var{flonums}}
3543 * Eject:: @code{.eject}
3544 * Else:: @code{.else}
3545 * Elseif:: @code{.elseif}
3548 * Endef:: @code{.endef}
3551 * Endfunc:: @code{.endfunc}
3552 * Endif:: @code{.endif}
3553 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3554 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3556 * Exitm:: @code{.exitm}
3557 * Extern:: @code{.extern}
3558 * Fail:: @code{.fail}
3559 @ifclear no-file-dir
3560 * File:: @code{.file @var{string}}
3563 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3564 * Float:: @code{.float @var{flonums}}
3565 * Func:: @code{.func}
3566 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3568 * Hidden:: @code{.hidden @var{names}}
3571 * hword:: @code{.hword @var{expressions}}
3572 * Ident:: @code{.ident}
3573 * If:: @code{.if @var{absolute expression}}
3574 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3575 * Include:: @code{.include "@var{file}"}
3576 * Int:: @code{.int @var{expressions}}
3578 * Internal:: @code{.internal @var{names}}
3581 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3582 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3583 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3584 * Lflags:: @code{.lflags}
3585 @ifclear no-line-dir
3586 * Line:: @code{.line @var{line-number}}
3589 * Ln:: @code{.ln @var{line-number}}
3590 * Linkonce:: @code{.linkonce [@var{type}]}
3591 * List:: @code{.list}
3592 * Long:: @code{.long @var{expressions}}
3594 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3597 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3598 * MRI:: @code{.mri @var{val}}
3599 * Nolist:: @code{.nolist}
3600 * Octa:: @code{.octa @var{bignums}}
3601 * Org:: @code{.org @var{new-lc} , @var{fill}}
3602 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3604 * PopSection:: @code{.popsection}
3605 * Previous:: @code{.previous}
3608 * Print:: @code{.print @var{string}}
3610 * Protected:: @code{.protected @var{names}}
3613 * Psize:: @code{.psize @var{lines}, @var{columns}}
3614 * Purgem:: @code{.purgem @var{name}}
3616 * PushSection:: @code{.pushsection @var{name}}
3619 * Quad:: @code{.quad @var{bignums}}
3620 * Rept:: @code{.rept @var{count}}
3621 * Sbttl:: @code{.sbttl "@var{subheading}"}
3623 * Scl:: @code{.scl @var{class}}
3624 * Section:: @code{.section @var{name}, @var{subsection}}
3627 * Set:: @code{.set @var{symbol}, @var{expression}}
3628 * Short:: @code{.short @var{expressions}}
3629 * Single:: @code{.single @var{flonums}}
3630 * Size:: @code{.size [@var{name} , @var{expression}]}
3631 * Skip:: @code{.skip @var{size} , @var{fill}}
3632 * Sleb128:: @code{.sleb128 @var{expressions}}
3633 * Space:: @code{.space @var{size} , @var{fill}}
3635 * Stab:: @code{.stabd, .stabn, .stabs}
3638 * String:: @code{.string "@var{str}"}
3639 * Struct:: @code{.struct @var{expression}}
3641 * SubSection:: @code{.subsection}
3642 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3646 * Tag:: @code{.tag @var{structname}}
3649 * Text:: @code{.text @var{subsection}}
3650 * Title:: @code{.title "@var{heading}"}
3651 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3652 * Uleb128:: @code{.uleb128 @var{expressions}}
3654 * Val:: @code{.val @var{addr}}
3658 * Version:: @code{.version "@var{string}"}
3659 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3660 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3661 * Weak:: @code{.weak @var{names}}
3664 * Word:: @code{.word @var{expressions}}
3665 * Deprecated:: Deprecated Directives
3669 @section @code{.abort}
3671 @cindex @code{abort} directive
3672 @cindex stopping the assembly
3673 This directive stops the assembly immediately. It is for
3674 compatibility with other assemblers. The original idea was that the
3675 assembly language source would be piped into the assembler. If the sender
3676 of the source quit, it could use this directive tells @command{@value{AS}} to
3677 quit also. One day @code{.abort} will not be supported.
3681 @section @code{.ABORT}
3683 @cindex @code{ABORT} directive
3684 When producing COFF output, @command{@value{AS}} accepts this directive as a
3685 synonym for @samp{.abort}.
3688 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3694 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3696 @cindex padding the location counter
3697 @cindex @code{align} directive
3698 Pad the location counter (in the current subsection) to a particular storage
3699 boundary. The first expression (which must be absolute) is the alignment
3700 required, as described below.
3702 The second expression (also absolute) gives the fill value to be stored in the
3703 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3704 padding bytes are normally zero. However, on some systems, if the section is
3705 marked as containing code and the fill value is omitted, the space is filled
3706 with no-op instructions.
3708 The third expression is also absolute, and is also optional. If it is present,
3709 it is the maximum number of bytes that should be skipped by this alignment
3710 directive. If doing the alignment would require skipping more bytes than the
3711 specified maximum, then the alignment is not done at all. You can omit the
3712 fill value (the second argument) entirely by simply using two commas after the
3713 required alignment; this can be useful if you want the alignment to be filled
3714 with no-op instructions when appropriate.
3716 The way the required alignment is specified varies from system to system.
3717 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3719 the first expression is the
3720 alignment request in bytes. For example @samp{.align 8} advances
3721 the location counter until it is a multiple of 8. If the location counter
3722 is already a multiple of 8, no change is needed.
3724 For other systems, including the i386 using a.out format, and the arm and
3725 strongarm, it is the
3726 number of low-order zero bits the location counter must have after
3727 advancement. For example @samp{.align 3} advances the location
3728 counter until it a multiple of 8. If the location counter is already a
3729 multiple of 8, no change is needed.
3731 This inconsistency is due to the different behaviors of the various
3732 native assemblers for these systems which GAS must emulate.
3733 GAS also provides @code{.balign} and @code{.p2align} directives,
3734 described later, which have a consistent behavior across all
3735 architectures (but are specific to GAS).
3738 @section @code{.ascii "@var{string}"}@dots{}
3740 @cindex @code{ascii} directive
3741 @cindex string literals
3742 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3743 separated by commas. It assembles each string (with no automatic
3744 trailing zero byte) into consecutive addresses.
3747 @section @code{.asciz "@var{string}"}@dots{}
3749 @cindex @code{asciz} directive
3750 @cindex zero-terminated strings
3751 @cindex null-terminated strings
3752 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3753 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3756 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3758 @cindex padding the location counter given number of bytes
3759 @cindex @code{balign} directive
3760 Pad the location counter (in the current subsection) to a particular
3761 storage boundary. The first expression (which must be absolute) is the
3762 alignment request in bytes. For example @samp{.balign 8} advances
3763 the location counter until it is a multiple of 8. If the location counter
3764 is already a multiple of 8, no change is needed.
3766 The second expression (also absolute) gives the fill value to be stored in the
3767 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3768 padding bytes are normally zero. However, on some systems, if the section is
3769 marked as containing code and the fill value is omitted, the space is filled
3770 with no-op instructions.
3772 The third expression is also absolute, and is also optional. If it is present,
3773 it is the maximum number of bytes that should be skipped by this alignment
3774 directive. If doing the alignment would require skipping more bytes than the
3775 specified maximum, then the alignment is not done at all. You can omit the
3776 fill value (the second argument) entirely by simply using two commas after the
3777 required alignment; this can be useful if you want the alignment to be filled
3778 with no-op instructions when appropriate.
3780 @cindex @code{balignw} directive
3781 @cindex @code{balignl} directive
3782 The @code{.balignw} and @code{.balignl} directives are variants of the
3783 @code{.balign} directive. The @code{.balignw} directive treats the fill
3784 pattern as a two byte word value. The @code{.balignl} directives treats the
3785 fill pattern as a four byte longword value. For example, @code{.balignw
3786 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3787 filled in with the value 0x368d (the exact placement of the bytes depends upon
3788 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3792 @section @code{.byte @var{expressions}}
3794 @cindex @code{byte} directive
3795 @cindex integers, one byte
3796 @code{.byte} expects zero or more expressions, separated by commas.
3797 Each expression is assembled into the next byte.
3800 @section @code{.comm @var{symbol} , @var{length} }
3802 @cindex @code{comm} directive
3803 @cindex symbol, common
3804 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3805 common symbol in one object file may be merged with a defined or common symbol
3806 of the same name in another object file. If @code{@value{LD}} does not see a
3807 definition for the symbol--just one or more common symbols--then it will
3808 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3809 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3810 the same name, and they do not all have the same size, it will allocate space
3811 using the largest size.
3814 When using ELF, the @code{.comm} directive takes an optional third argument.
3815 This is the desired alignment of the symbol, specified as a byte boundary (for
3816 example, an alignment of 16 means that the least significant 4 bits of the
3817 address should be zero). The alignment must be an absolute expression, and it
3818 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3819 for the common symbol, it will use the alignment when placing the symbol. If
3820 no alignment is specified, @command{@value{AS}} will set the alignment to the
3821 largest power of two less than or equal to the size of the symbol, up to a
3826 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3827 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3831 @section @code{.data @var{subsection}}
3833 @cindex @code{data} directive
3834 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3835 end of the data subsection numbered @var{subsection} (which is an
3836 absolute expression). If @var{subsection} is omitted, it defaults
3841 @section @code{.def @var{name}}
3843 @cindex @code{def} directive
3844 @cindex COFF symbols, debugging
3845 @cindex debugging COFF symbols
3846 Begin defining debugging information for a symbol @var{name}; the
3847 definition extends until the @code{.endef} directive is encountered.
3850 This directive is only observed when @command{@value{AS}} is configured for COFF
3851 format output; when producing @code{b.out}, @samp{.def} is recognized,
3858 @section @code{.desc @var{symbol}, @var{abs-expression}}
3860 @cindex @code{desc} directive
3861 @cindex COFF symbol descriptor
3862 @cindex symbol descriptor, COFF
3863 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3864 to the low 16 bits of an absolute expression.
3867 The @samp{.desc} directive is not available when @command{@value{AS}} is
3868 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3869 object format. For the sake of compatibility, @command{@value{AS}} accepts
3870 it, but produces no output, when configured for COFF.
3876 @section @code{.dim}
3878 @cindex @code{dim} directive
3879 @cindex COFF auxiliary symbol information
3880 @cindex auxiliary symbol information, COFF
3881 This directive is generated by compilers to include auxiliary debugging
3882 information in the symbol table. It is only permitted inside
3883 @code{.def}/@code{.endef} pairs.
3886 @samp{.dim} is only meaningful when generating COFF format output; when
3887 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3893 @section @code{.double @var{flonums}}
3895 @cindex @code{double} directive
3896 @cindex floating point numbers (double)
3897 @code{.double} expects zero or more flonums, separated by commas. It
3898 assembles floating point numbers.
3900 The exact kind of floating point numbers emitted depends on how
3901 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3905 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3906 in @sc{ieee} format.
3911 @section @code{.eject}
3913 @cindex @code{eject} directive
3914 @cindex new page, in listings
3915 @cindex page, in listings
3916 @cindex listing control: new page
3917 Force a page break at this point, when generating assembly listings.
3920 @section @code{.else}
3922 @cindex @code{else} directive
3923 @code{.else} is part of the @command{@value{AS}} support for conditional
3924 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3925 of code to be assembled if the condition for the preceding @code{.if}
3929 @section @code{.elseif}
3931 @cindex @code{elseif} directive
3932 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3933 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3934 @code{.if} block that would otherwise fill the entire @code{.else} section.
3937 @section @code{.end}
3939 @cindex @code{end} directive
3940 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3941 process anything in the file past the @code{.end} directive.
3945 @section @code{.endef}
3947 @cindex @code{endef} directive
3948 This directive flags the end of a symbol definition begun with
3952 @samp{.endef} is only meaningful when generating COFF format output; if
3953 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3954 directive but ignores it.
3959 @section @code{.endfunc}
3960 @cindex @code{endfunc} directive
3961 @code{.endfunc} marks the end of a function specified with @code{.func}.
3964 @section @code{.endif}
3966 @cindex @code{endif} directive
3967 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3968 it marks the end of a block of code that is only assembled
3969 conditionally. @xref{If,,@code{.if}}.
3972 @section @code{.equ @var{symbol}, @var{expression}}
3974 @cindex @code{equ} directive
3975 @cindex assigning values to symbols
3976 @cindex symbols, assigning values to
3977 This directive sets the value of @var{symbol} to @var{expression}.
3978 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3981 The syntax for @code{equ} on the HPPA is
3982 @samp{@var{symbol} .equ @var{expression}}.
3986 @section @code{.equiv @var{symbol}, @var{expression}}
3987 @cindex @code{equiv} directive
3988 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3989 the assembler will signal an error if @var{symbol} is already defined.
3991 Except for the contents of the error message, this is roughly equivalent to
4000 @section @code{.err}
4001 @cindex @code{err} directive
4002 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4003 message and, unless the @option{-Z} option was used, it will not generate an
4004 object file. This can be used to signal error an conditionally compiled code.
4007 @section @code{.exitm}
4008 Exit early from the current macro definition. @xref{Macro}.
4011 @section @code{.extern}
4013 @cindex @code{extern} directive
4014 @code{.extern} is accepted in the source program---for compatibility
4015 with other assemblers---but it is ignored. @command{@value{AS}} treats
4016 all undefined symbols as external.
4019 @section @code{.fail @var{expression}}
4021 @cindex @code{fail} directive
4022 Generates an error or a warning. If the value of the @var{expression} is 500
4023 or more, @command{@value{AS}} will print a warning message. If the value is less
4024 than 500, @command{@value{AS}} will print an error message. The message will
4025 include the value of @var{expression}. This can occasionally be useful inside
4026 complex nested macros or conditional assembly.
4028 @ifclear no-file-dir
4030 @section @code{.file @var{string}}
4032 @cindex @code{file} directive
4033 @cindex logical file name
4034 @cindex file name, logical
4035 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4036 file. @var{string} is the new file name. In general, the filename is
4037 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4038 to specify an empty file name, you must give the quotes--@code{""}. This
4039 statement may go away in future: it is only recognized to be compatible with
4040 old @command{@value{AS}} programs.
4042 In some configurations of @command{@value{AS}}, @code{.file} has already been
4043 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4048 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4050 @cindex @code{fill} directive
4051 @cindex writing patterns in memory
4052 @cindex patterns, writing in memory
4053 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4054 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4055 may be zero or more. @var{Size} may be zero or more, but if it is
4056 more than 8, then it is deemed to have the value 8, compatible with
4057 other people's assemblers. The contents of each @var{repeat} bytes
4058 is taken from an 8-byte number. The highest order 4 bytes are
4059 zero. The lowest order 4 bytes are @var{value} rendered in the
4060 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4061 Each @var{size} bytes in a repetition is taken from the lowest order
4062 @var{size} bytes of this number. Again, this bizarre behavior is
4063 compatible with other people's assemblers.
4065 @var{size} and @var{value} are optional.
4066 If the second comma and @var{value} are absent, @var{value} is
4067 assumed zero. If the first comma and following tokens are absent,
4068 @var{size} is assumed to be 1.
4071 @section @code{.float @var{flonums}}
4073 @cindex floating point numbers (single)
4074 @cindex @code{float} directive
4075 This directive assembles zero or more flonums, separated by commas. It
4076 has the same effect as @code{.single}.
4078 The exact kind of floating point numbers emitted depends on how
4079 @command{@value{AS}} is configured.
4080 @xref{Machine Dependencies}.
4084 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4085 in @sc{ieee} format.
4090 @section @code{.func @var{name}[,@var{label}]}
4091 @cindex @code{func} directive
4092 @code{.func} emits debugging information to denote function @var{name}, and
4093 is ignored unless the file is assembled with debugging enabled.
4094 Only @samp{--gstabs} is currently supported.
4095 @var{label} is the entry point of the function and if omitted @var{name}
4096 prepended with the @samp{leading char} is used.
4097 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4098 All functions are currently defined to have @code{void} return type.
4099 The function must be terminated with @code{.endfunc}.
4102 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4104 @cindex @code{global} directive
4105 @cindex symbol, making visible to linker
4106 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4107 @var{symbol} in your partial program, its value is made available to
4108 other partial programs that are linked with it. Otherwise,
4109 @var{symbol} takes its attributes from a symbol of the same name
4110 from another file linked into the same program.
4112 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4113 compatibility with other assemblers.
4116 On the HPPA, @code{.global} is not always enough to make it accessible to other
4117 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4118 @xref{HPPA Directives,, HPPA Assembler Directives}.
4123 @section @code{.hidden @var{names}}
4125 @cindex @code{.hidden} directive
4127 This one of the ELF visibility directives. The other two are
4128 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4129 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4131 This directive overrides the named symbols default visibility (which is set by
4132 their binding: local, global or weak). The directive sets the visibility to
4133 @code{hidden} which means that the symbols are not visible to other components.
4134 Such symbols are always considered to be @code{protected} as well.
4138 @section @code{.hword @var{expressions}}
4140 @cindex @code{hword} directive
4141 @cindex integers, 16-bit
4142 @cindex numbers, 16-bit
4143 @cindex sixteen bit integers
4144 This expects zero or more @var{expressions}, and emits
4145 a 16 bit number for each.
4148 This directive is a synonym for @samp{.short}; depending on the target
4149 architecture, it may also be a synonym for @samp{.word}.
4153 This directive is a synonym for @samp{.short}.
4156 This directive is a synonym for both @samp{.short} and @samp{.word}.
4161 @section @code{.ident}
4163 @cindex @code{ident} directive
4164 This directive is used by some assemblers to place tags in object files.
4165 @command{@value{AS}} simply accepts the directive for source-file
4166 compatibility with such assemblers, but does not actually emit anything
4170 @section @code{.if @var{absolute expression}}
4172 @cindex conditional assembly
4173 @cindex @code{if} directive
4174 @code{.if} marks the beginning of a section of code which is only
4175 considered part of the source program being assembled if the argument
4176 (which must be an @var{absolute expression}) is non-zero. The end of
4177 the conditional section of code must be marked by @code{.endif}
4178 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4179 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4180 If you have several conditions to check, @code{.elseif} may be used to avoid
4181 nesting blocks if/else within each subsequent @code{.else} block.
4183 The following variants of @code{.if} are also supported:
4185 @cindex @code{ifdef} directive
4186 @item .ifdef @var{symbol}
4187 Assembles the following section of code if the specified @var{symbol}
4190 @cindex @code{ifc} directive
4191 @item .ifc @var{string1},@var{string2}
4192 Assembles the following section of code if the two strings are the same. The
4193 strings may be optionally quoted with single quotes. If they are not quoted,
4194 the first string stops at the first comma, and the second string stops at the
4195 end of the line. Strings which contain whitespace should be quoted. The
4196 string comparison is case sensitive.
4198 @cindex @code{ifeq} directive
4199 @item .ifeq @var{absolute expression}
4200 Assembles the following section of code if the argument is zero.
4202 @cindex @code{ifeqs} directive
4203 @item .ifeqs @var{string1},@var{string2}
4204 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4206 @cindex @code{ifge} directive
4207 @item .ifge @var{absolute expression}
4208 Assembles the following section of code if the argument is greater than or
4211 @cindex @code{ifgt} directive
4212 @item .ifgt @var{absolute expression}
4213 Assembles the following section of code if the argument is greater than zero.
4215 @cindex @code{ifle} directive
4216 @item .ifle @var{absolute expression}
4217 Assembles the following section of code if the argument is less than or equal
4220 @cindex @code{iflt} directive
4221 @item .iflt @var{absolute expression}
4222 Assembles the following section of code if the argument is less than zero.
4224 @cindex @code{ifnc} directive
4225 @item .ifnc @var{string1},@var{string2}.
4226 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4227 following section of code if the two strings are not the same.
4229 @cindex @code{ifndef} directive
4230 @cindex @code{ifnotdef} directive
4231 @item .ifndef @var{symbol}
4232 @itemx .ifnotdef @var{symbol}
4233 Assembles the following section of code if the specified @var{symbol}
4234 has not been defined. Both spelling variants are equivalent.
4236 @cindex @code{ifne} directive
4237 @item .ifne @var{absolute expression}
4238 Assembles the following section of code if the argument is not equal to zero
4239 (in other words, this is equivalent to @code{.if}).
4241 @cindex @code{ifnes} directive
4242 @item .ifnes @var{string1},@var{string2}
4243 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4244 following section of code if the two strings are not the same.
4248 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4250 @cindex @code{incbin} directive
4251 @cindex binary files, including
4252 The @code{incbin} directive includes @var{file} verbatim at the current
4253 location. You can control the search paths used with the @samp{-I} command-line
4254 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4257 The @var{skip} argument skips a number of bytes from the start of the
4258 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4259 read. Note that the data is not aligned in any way, so it is the user's
4260 responsibility to make sure that proper alignment is provided both before and
4261 after the @code{incbin} directive.
4264 @section @code{.include "@var{file}"}
4266 @cindex @code{include} directive
4267 @cindex supporting files, including
4268 @cindex files, including
4269 This directive provides a way to include supporting files at specified
4270 points in your source program. The code from @var{file} is assembled as
4271 if it followed the point of the @code{.include}; when the end of the
4272 included file is reached, assembly of the original file continues. You
4273 can control the search paths used with the @samp{-I} command-line option
4274 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4278 @section @code{.int @var{expressions}}
4280 @cindex @code{int} directive
4281 @cindex integers, 32-bit
4282 Expect zero or more @var{expressions}, of any section, separated by commas.
4283 For each expression, emit a number that, at run time, is the value of that
4284 expression. The byte order and bit size of the number depends on what kind
4285 of target the assembly is for.
4289 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4290 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4297 @section @code{.internal @var{names}}
4299 @cindex @code{.internal} directive
4301 This one of the ELF visibility directives. The other two are
4302 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4303 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4305 This directive overrides the named symbols default visibility (which is set by
4306 their binding: local, global or weak). The directive sets the visibility to
4307 @code{internal} which means that the symbols are considered to be @code{hidden}
4308 (ie not visible to other components), and that some extra, processor specific
4309 processing must also be performed upon the symbols as well.
4313 @section @code{.irp @var{symbol},@var{values}}@dots{}
4315 @cindex @code{irp} directive
4316 Evaluate a sequence of statements assigning different values to @var{symbol}.
4317 The sequence of statements starts at the @code{.irp} directive, and is
4318 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4319 set to @var{value}, and the sequence of statements is assembled. If no
4320 @var{value} is listed, the sequence of statements is assembled once, with
4321 @var{symbol} set to the null string. To refer to @var{symbol} within the
4322 sequence of statements, use @var{\symbol}.
4324 For example, assembling
4332 is equivalent to assembling
4341 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4343 @cindex @code{irpc} directive
4344 Evaluate a sequence of statements assigning different values to @var{symbol}.
4345 The sequence of statements starts at the @code{.irpc} directive, and is
4346 terminated by an @code{.endr} directive. For each character in @var{value},
4347 @var{symbol} is set to the character, and the sequence of statements is
4348 assembled. If no @var{value} is listed, the sequence of statements is
4349 assembled once, with @var{symbol} set to the null string. To refer to
4350 @var{symbol} within the sequence of statements, use @var{\symbol}.
4352 For example, assembling
4360 is equivalent to assembling
4369 @section @code{.lcomm @var{symbol} , @var{length}}
4371 @cindex @code{lcomm} directive
4372 @cindex local common symbols
4373 @cindex symbols, local common
4374 Reserve @var{length} (an absolute expression) bytes for a local common
4375 denoted by @var{symbol}. The section and value of @var{symbol} are
4376 those of the new local common. The addresses are allocated in the bss
4377 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4378 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4379 not visible to @code{@value{LD}}.
4382 Some targets permit a third argument to be used with @code{.lcomm}. This
4383 argument specifies the desired alignment of the symbol in the bss section.
4387 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4388 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4392 @section @code{.lflags}
4394 @cindex @code{lflags} directive (ignored)
4395 @command{@value{AS}} accepts this directive, for compatibility with other
4396 assemblers, but ignores it.
4398 @ifclear no-line-dir
4400 @section @code{.line @var{line-number}}
4402 @cindex @code{line} directive
4406 @section @code{.ln @var{line-number}}
4408 @cindex @code{ln} directive
4410 @cindex logical line number
4412 Change the logical line number. @var{line-number} must be an absolute
4413 expression. The next line has that logical line number. Therefore any other
4414 statements on the current line (after a statement separator character) are
4415 reported as on logical line number @var{line-number} @minus{} 1. One day
4416 @command{@value{AS}} will no longer support this directive: it is recognized only
4417 for compatibility with existing assembler programs.
4421 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4422 not available; use the synonym @code{.ln} in that context.
4427 @ifclear no-line-dir
4428 Even though this is a directive associated with the @code{a.out} or
4429 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4430 when producing COFF output, and treats @samp{.line} as though it
4431 were the COFF @samp{.ln} @emph{if} it is found outside a
4432 @code{.def}/@code{.endef} pair.
4434 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4435 used by compilers to generate auxiliary symbol information for
4440 @section @code{.linkonce [@var{type}]}
4442 @cindex @code{linkonce} directive
4443 @cindex common sections
4444 Mark the current section so that the linker only includes a single copy of it.
4445 This may be used to include the same section in several different object files,
4446 but ensure that the linker will only include it once in the final output file.
4447 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4448 Duplicate sections are detected based on the section name, so it should be
4451 This directive is only supported by a few object file formats; as of this
4452 writing, the only object file format which supports it is the Portable
4453 Executable format used on Windows NT.
4455 The @var{type} argument is optional. If specified, it must be one of the
4456 following strings. For example:
4460 Not all types may be supported on all object file formats.
4464 Silently discard duplicate sections. This is the default.
4467 Warn if there are duplicate sections, but still keep only one copy.
4470 Warn if any of the duplicates have different sizes.
4473 Warn if any of the duplicates do not have exactly the same contents.
4477 @section @code{.ln @var{line-number}}
4479 @cindex @code{ln} directive
4480 @ifclear no-line-dir
4481 @samp{.ln} is a synonym for @samp{.line}.
4484 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4485 must be an absolute expression. The next line has that logical
4486 line number, so any other statements on the current line (after a
4487 statement separator character @code{;}) are reported as on logical
4488 line number @var{line-number} @minus{} 1.
4491 This directive is accepted, but ignored, when @command{@value{AS}} is
4492 configured for @code{b.out}; its effect is only associated with COFF
4498 @section @code{.mri @var{val}}
4500 @cindex @code{mri} directive
4501 @cindex MRI mode, temporarily
4502 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4503 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4504 affects code assembled until the next @code{.mri} directive, or until the end
4505 of the file. @xref{M, MRI mode, MRI mode}.
4508 @section @code{.list}
4510 @cindex @code{list} directive
4511 @cindex listing control, turning on
4512 Control (in conjunction with the @code{.nolist} directive) whether or
4513 not assembly listings are generated. These two directives maintain an
4514 internal counter (which is zero initially). @code{.list} increments the
4515 counter, and @code{.nolist} decrements it. Assembly listings are
4516 generated whenever the counter is greater than zero.
4518 By default, listings are disabled. When you enable them (with the
4519 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4520 the initial value of the listing counter is one.
4523 @section @code{.long @var{expressions}}
4525 @cindex @code{long} directive
4526 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4529 @c no one seems to know what this is for or whether this description is
4530 @c what it really ought to do
4532 @section @code{.lsym @var{symbol}, @var{expression}}
4534 @cindex @code{lsym} directive
4535 @cindex symbol, not referenced in assembly
4536 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4537 the hash table, ensuring it cannot be referenced by name during the
4538 rest of the assembly. This sets the attributes of the symbol to be
4539 the same as the expression value:
4541 @var{other} = @var{descriptor} = 0
4542 @var{type} = @r{(section of @var{expression})}
4543 @var{value} = @var{expression}
4546 The new symbol is not flagged as external.
4550 @section @code{.macro}
4553 The commands @code{.macro} and @code{.endm} allow you to define macros that
4554 generate assembly output. For example, this definition specifies a macro
4555 @code{sum} that puts a sequence of numbers into memory:
4558 .macro sum from=0, to=5
4567 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4579 @item .macro @var{macname}
4580 @itemx .macro @var{macname} @var{macargs} @dots{}
4581 @cindex @code{macro} directive
4582 Begin the definition of a macro called @var{macname}. If your macro
4583 definition requires arguments, specify their names after the macro name,
4584 separated by commas or spaces. You can supply a default value for any
4585 macro argument by following the name with @samp{=@var{deflt}}. For
4586 example, these are all valid @code{.macro} statements:
4590 Begin the definition of a macro called @code{comm}, which takes no
4593 @item .macro plus1 p, p1
4594 @itemx .macro plus1 p p1
4595 Either statement begins the definition of a macro called @code{plus1},
4596 which takes two arguments; within the macro definition, write
4597 @samp{\p} or @samp{\p1} to evaluate the arguments.
4599 @item .macro reserve_str p1=0 p2
4600 Begin the definition of a macro called @code{reserve_str}, with two
4601 arguments. The first argument has a default value, but not the second.
4602 After the definition is complete, you can call the macro either as
4603 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4604 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4605 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4606 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4609 When you call a macro, you can specify the argument values either by
4610 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4611 @samp{sum to=17, from=9}.
4614 @cindex @code{endm} directive
4615 Mark the end of a macro definition.
4618 @cindex @code{exitm} directive
4619 Exit early from the current macro definition.
4621 @cindex number of macros executed
4622 @cindex macros, count executed
4624 @command{@value{AS}} maintains a counter of how many macros it has
4625 executed in this pseudo-variable; you can copy that number to your
4626 output with @samp{\@@}, but @emph{only within a macro definition}.
4629 @item LOCAL @var{name} [ , @dots{} ]
4630 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4631 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4632 Alternate macro syntax}.
4634 Generate a string replacement for each of the @var{name} arguments, and
4635 replace any instances of @var{name} in each macro expansion. The
4636 replacement string is unique in the assembly, and different for each
4637 separate macro expansion. @code{LOCAL} allows you to write macros that
4638 define symbols, without fear of conflict between separate macro expansions.
4643 @section @code{.nolist}
4645 @cindex @code{nolist} directive
4646 @cindex listing control, turning off
4647 Control (in conjunction with the @code{.list} directive) whether or
4648 not assembly listings are generated. These two directives maintain an
4649 internal counter (which is zero initially). @code{.list} increments the
4650 counter, and @code{.nolist} decrements it. Assembly listings are
4651 generated whenever the counter is greater than zero.
4654 @section @code{.octa @var{bignums}}
4656 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4657 @cindex @code{octa} directive
4658 @cindex integer, 16-byte
4659 @cindex sixteen byte integer
4660 This directive expects zero or more bignums, separated by commas. For each
4661 bignum, it emits a 16-byte integer.
4663 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4664 hence @emph{octa}-word for 16 bytes.
4667 @section @code{.org @var{new-lc} , @var{fill}}
4669 @cindex @code{org} directive
4670 @cindex location counter, advancing
4671 @cindex advancing location counter
4672 @cindex current address, advancing
4673 Advance the location counter of the current section to
4674 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4675 expression with the same section as the current subsection. That is,
4676 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4677 wrong section, the @code{.org} directive is ignored. To be compatible
4678 with former assemblers, if the section of @var{new-lc} is absolute,
4679 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4680 is the same as the current subsection.
4682 @code{.org} may only increase the location counter, or leave it
4683 unchanged; you cannot use @code{.org} to move the location counter
4686 @c double negative used below "not undefined" because this is a specific
4687 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4688 @c section. doc@cygnus.com 18feb91
4689 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4690 may not be undefined. If you really detest this restriction we eagerly await
4691 a chance to share your improved assembler.
4693 Beware that the origin is relative to the start of the section, not
4694 to the start of the subsection. This is compatible with other
4695 people's assemblers.
4697 When the location counter (of the current subsection) is advanced, the
4698 intervening bytes are filled with @var{fill} which should be an
4699 absolute expression. If the comma and @var{fill} are omitted,
4700 @var{fill} defaults to zero.
4703 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4705 @cindex padding the location counter given a power of two
4706 @cindex @code{p2align} directive
4707 Pad the location counter (in the current subsection) to a particular
4708 storage boundary. The first expression (which must be absolute) is the
4709 number of low-order zero bits the location counter must have after
4710 advancement. For example @samp{.p2align 3} advances the location
4711 counter until it a multiple of 8. If the location counter is already a
4712 multiple of 8, no change is needed.
4714 The second expression (also absolute) gives the fill value to be stored in the
4715 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4716 padding bytes are normally zero. However, on some systems, if the section is
4717 marked as containing code and the fill value is omitted, the space is filled
4718 with no-op instructions.
4720 The third expression is also absolute, and is also optional. If it is present,
4721 it is the maximum number of bytes that should be skipped by this alignment
4722 directive. If doing the alignment would require skipping more bytes than the
4723 specified maximum, then the alignment is not done at all. You can omit the
4724 fill value (the second argument) entirely by simply using two commas after the
4725 required alignment; this can be useful if you want the alignment to be filled
4726 with no-op instructions when appropriate.
4728 @cindex @code{p2alignw} directive
4729 @cindex @code{p2alignl} directive
4730 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4731 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4732 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4733 fill pattern as a four byte longword value. For example, @code{.p2alignw
4734 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4735 filled in with the value 0x368d (the exact placement of the bytes depends upon
4736 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4741 @section @code{.previous}
4743 @cindex @code{.previous} directive
4744 @cindex Section Stack
4745 This is one of the ELF section stack manipulation directives. The others are
4746 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4747 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4748 (@pxref{PopSection}).
4750 This directive swaps the current section (and subsection) with most recently
4751 referenced section (and subsection) prior to this one. Multiple
4752 @code{.previous} directives in a row will flip between two sections (and their
4755 In terms of the section stack, this directive swaps the current section with
4756 the top section on the section stack.
4761 @section @code{.popsection}
4763 @cindex @code{.popsection} directive
4764 @cindex Section Stack
4765 This is one of the ELF section stack manipulation directives. The others are
4766 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4767 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4770 This directive replaces the current section (and subsection) with the top
4771 section (and subsection) on the section stack. This section is popped off the
4776 @section @code{.print @var{string}}
4778 @cindex @code{print} directive
4779 @command{@value{AS}} will print @var{string} on the standard output during
4780 assembly. You must put @var{string} in double quotes.
4784 @section @code{.protected @var{names}}
4786 @cindex @code{.protected} directive
4788 This one of the ELF visibility directives. The other two are
4789 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4791 This directive overrides the named symbols default visibility (which is set by
4792 their binding: local, global or weak). The directive sets the visibility to
4793 @code{protected} which means that any references to the symbols from within the
4794 components that defines them must be resolved to the definition in that
4795 component, even if a definition in another component would normally preempt
4800 @section @code{.psize @var{lines} , @var{columns}}
4802 @cindex @code{psize} directive
4803 @cindex listing control: paper size
4804 @cindex paper size, for listings
4805 Use this directive to declare the number of lines---and, optionally, the
4806 number of columns---to use for each page, when generating listings.
4808 If you do not use @code{.psize}, listings use a default line-count
4809 of 60. You may omit the comma and @var{columns} specification; the
4810 default width is 200 columns.
4812 @command{@value{AS}} generates formfeeds whenever the specified number of
4813 lines is exceeded (or whenever you explicitly request one, using
4816 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4817 those explicitly specified with @code{.eject}.
4820 @section @code{.purgem @var{name}}
4822 @cindex @code{purgem} directive
4823 Undefine the macro @var{name}, so that later uses of the string will not be
4824 expanded. @xref{Macro}.
4828 @section @code{.pushsection @var{name} , @var{subsection}}
4830 @cindex @code{.pushsection} directive
4831 @cindex Section Stack
4832 This is one of the ELF section stack manipulation directives. The others are
4833 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4834 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4837 This directive is a synonym for @code{.section}. It pushes the current section
4838 (and subsection) onto the top of the section stack, and then replaces the
4839 current section and subsection with @code{name} and @code{subsection}.
4843 @section @code{.quad @var{bignums}}
4845 @cindex @code{quad} directive
4846 @code{.quad} expects zero or more bignums, separated by commas. For
4847 each bignum, it emits
4849 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4850 warning message; and just takes the lowest order 8 bytes of the bignum.
4851 @cindex eight-byte integer
4852 @cindex integer, 8-byte
4854 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4855 hence @emph{quad}-word for 8 bytes.
4858 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4859 warning message; and just takes the lowest order 16 bytes of the bignum.
4860 @cindex sixteen-byte integer
4861 @cindex integer, 16-byte
4865 @section @code{.rept @var{count}}
4867 @cindex @code{rept} directive
4868 Repeat the sequence of lines between the @code{.rept} directive and the next
4869 @code{.endr} directive @var{count} times.
4871 For example, assembling
4879 is equivalent to assembling
4888 @section @code{.sbttl "@var{subheading}"}
4890 @cindex @code{sbttl} directive
4891 @cindex subtitles for listings
4892 @cindex listing control: subtitle
4893 Use @var{subheading} as the title (third line, immediately after the
4894 title line) when generating assembly listings.
4896 This directive affects subsequent pages, as well as the current page if
4897 it appears within ten lines of the top of a page.
4901 @section @code{.scl @var{class}}
4903 @cindex @code{scl} directive
4904 @cindex symbol storage class (COFF)
4905 @cindex COFF symbol storage class
4906 Set the storage-class value for a symbol. This directive may only be
4907 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4908 whether a symbol is static or external, or it may record further
4909 symbolic debugging information.
4912 The @samp{.scl} directive is primarily associated with COFF output; when
4913 configured to generate @code{b.out} output format, @command{@value{AS}}
4914 accepts this directive but ignores it.
4919 @section @code{.section @var{name}} (COFF version)
4921 @cindex @code{section} directive
4922 @cindex named section
4923 Use the @code{.section} directive to assemble the following code into a section
4926 This directive is only supported for targets that actually support arbitrarily
4927 named sections; on @code{a.out} targets, for example, it is not accepted, even
4928 with a standard @code{a.out} section name.
4930 For COFF targets, the @code{.section} directive is used in one of the following
4934 .section @var{name}[, "@var{flags}"]
4935 .section @var{name}[, @var{subsegment}]
4938 If the optional argument is quoted, it is taken as flags to use for the
4939 section. Each flag is a single character. The following flags are recognized:
4942 bss section (uninitialized data)
4944 section is not loaded
4954 shared section (meaningful for PE targets)
4957 If no flags are specified, the default flags depend upon the section name. If
4958 the section name is not recognized, the default will be for the section to be
4959 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4960 from the section, rather than adding them, so if they are used on their own it
4961 will be as if no flags had been specified at all.
4963 If the optional argument to the @code{.section} directive is not quoted, it is
4964 taken as a subsegment number (@pxref{Sub-Sections}).
4967 @section @code{.section @var{name}} (ELF version)
4969 @cindex @code{section} directive
4970 @cindex named section
4972 @cindex Section Stack
4973 This is one of the ELF section stack manipulation directives. The others are
4974 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4975 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4976 @code{.previous} (@pxref{Previous}).
4979 For ELF targets, the @code{.section} directive is used like this:
4982 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
4985 The optional @var{flags} argument is a quoted string which may contain any
4986 combination of the following characters:
4989 section is allocatable
4993 section is executable
4995 section is mergeable
4997 section contains zero terminated strings
5000 The optional @var{type} argument may contain one of the following constants:
5003 section contains data
5005 section does not contain data (i.e., section only occupies space)
5008 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5009 as well as @var{entsize} argument. Sections with @code{M} flag but not
5010 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5011 long. Sections with both @code{M} and @code{S} must contain zero terminated
5012 strings where each character is @var{entsize} bytes long. The linker may remove
5013 duplicates within sections with the same name, same entity size and same flags.
5015 If no flags are specified, the default flags depend upon the section name. If
5016 the section name is not recognized, the default will be for the section to have
5017 none of the above flags: it will not be allocated in memory, nor writable, nor
5018 executable. The section will contain data.
5020 For ELF targets, the assembler supports another type of @code{.section}
5021 directive for compatibility with the Solaris assembler:
5024 .section "@var{name}"[, @var{flags}...]
5027 Note that the section name is quoted. There may be a sequence of comma
5031 section is allocatable
5035 section is executable
5038 This directive replaces the current section and subsection. The replaced
5039 section and subsection are pushed onto the section stack. See the contents of
5040 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5041 how this directive and the other section stack directives work.
5044 @section @code{.set @var{symbol}, @var{expression}}
5046 @cindex @code{set} directive
5047 @cindex symbol value, setting
5048 Set the value of @var{symbol} to @var{expression}. This
5049 changes @var{symbol}'s value and type to conform to
5050 @var{expression}. If @var{symbol} was flagged as external, it remains
5051 flagged (@pxref{Symbol Attributes}).
5053 You may @code{.set} a symbol many times in the same assembly.
5055 If you @code{.set} a global symbol, the value stored in the object
5056 file is the last value stored into it.
5059 The syntax for @code{set} on the HPPA is
5060 @samp{@var{symbol} .set @var{expression}}.
5064 @section @code{.short @var{expressions}}
5066 @cindex @code{short} directive
5068 @code{.short} is normally the same as @samp{.word}.
5069 @xref{Word,,@code{.word}}.
5071 In some configurations, however, @code{.short} and @code{.word} generate
5072 numbers of different lengths; @pxref{Machine Dependencies}.
5076 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5079 This expects zero or more @var{expressions}, and emits
5080 a 16 bit number for each.
5085 @section @code{.single @var{flonums}}
5087 @cindex @code{single} directive
5088 @cindex floating point numbers (single)
5089 This directive assembles zero or more flonums, separated by commas. It
5090 has the same effect as @code{.float}.
5092 The exact kind of floating point numbers emitted depends on how
5093 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5097 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5098 numbers in @sc{ieee} format.
5103 @section @code{.size} (COFF version)
5105 @cindex @code{size} directive
5106 This directive is generated by compilers to include auxiliary debugging
5107 information in the symbol table. It is only permitted inside
5108 @code{.def}/@code{.endef} pairs.
5111 @samp{.size} is only meaningful when generating COFF format output; when
5112 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5116 @section @code{.size @var{name} , @var{expression}} (ELF version)
5117 @cindex @code{size} directive
5119 This directive is used to set the size associated with a symbol @var{name}.
5120 The size in bytes is computed from @var{expression} which can make use of label
5121 arithmetic. This directive is typically used to set the size of function
5125 @section @code{.sleb128 @var{expressions}}
5127 @cindex @code{sleb128} directive
5128 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5129 compact, variable length representation of numbers used by the DWARF
5130 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5132 @ifclear no-space-dir
5134 @section @code{.skip @var{size} , @var{fill}}
5136 @cindex @code{skip} directive
5137 @cindex filling memory
5138 This directive emits @var{size} bytes, each of value @var{fill}. Both
5139 @var{size} and @var{fill} are absolute expressions. If the comma and
5140 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5144 @section @code{.space @var{size} , @var{fill}}
5146 @cindex @code{space} directive
5147 @cindex filling memory
5148 This directive emits @var{size} bytes, each of value @var{fill}. Both
5149 @var{size} and @var{fill} are absolute expressions. If the comma
5150 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5155 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5156 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5157 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5158 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5167 @section @code{.space}
5168 @cindex @code{space} directive
5170 On the AMD 29K, this directive is ignored; it is accepted for
5171 compatibility with other AMD 29K assemblers.
5174 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5175 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5181 @section @code{.stabd, .stabn, .stabs}
5183 @cindex symbolic debuggers, information for
5184 @cindex @code{stab@var{x}} directives
5185 There are three directives that begin @samp{.stab}.
5186 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5187 The symbols are not entered in the @command{@value{AS}} hash table: they
5188 cannot be referenced elsewhere in the source file.
5189 Up to five fields are required:
5193 This is the symbol's name. It may contain any character except
5194 @samp{\000}, so is more general than ordinary symbol names. Some
5195 debuggers used to code arbitrarily complex structures into symbol names
5199 An absolute expression. The symbol's type is set to the low 8 bits of
5200 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5201 and debuggers choke on silly bit patterns.
5204 An absolute expression. The symbol's ``other'' attribute is set to the
5205 low 8 bits of this expression.
5208 An absolute expression. The symbol's descriptor is set to the low 16
5209 bits of this expression.
5212 An absolute expression which becomes the symbol's value.
5215 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5216 or @code{.stabs} statement, the symbol has probably already been created;
5217 you get a half-formed symbol in your object file. This is
5218 compatible with earlier assemblers!
5221 @cindex @code{stabd} directive
5222 @item .stabd @var{type} , @var{other} , @var{desc}
5224 The ``name'' of the symbol generated is not even an empty string.
5225 It is a null pointer, for compatibility. Older assemblers used a
5226 null pointer so they didn't waste space in object files with empty
5229 The symbol's value is set to the location counter,
5230 relocatably. When your program is linked, the value of this symbol
5231 is the address of the location counter when the @code{.stabd} was
5234 @cindex @code{stabn} directive
5235 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5236 The name of the symbol is set to the empty string @code{""}.
5238 @cindex @code{stabs} directive
5239 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5240 All five fields are specified.
5246 @section @code{.string} "@var{str}"
5248 @cindex string, copying to object file
5249 @cindex @code{string} directive
5251 Copy the characters in @var{str} to the object file. You may specify more than
5252 one string to copy, separated by commas. Unless otherwise specified for a
5253 particular machine, the assembler marks the end of each string with a 0 byte.
5254 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5257 @section @code{.struct @var{expression}}
5259 @cindex @code{struct} directive
5260 Switch to the absolute section, and set the section offset to @var{expression},
5261 which must be an absolute expression. You might use this as follows:
5270 This would define the symbol @code{field1} to have the value 0, the symbol
5271 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5272 value 8. Assembly would be left in the absolute section, and you would need to
5273 use a @code{.section} directive of some sort to change to some other section
5274 before further assembly.
5278 @section @code{.subsection @var{name}}
5280 @cindex @code{.subsection} directive
5281 @cindex Section Stack
5282 This is one of the ELF section stack manipulation directives. The others are
5283 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5284 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5287 This directive replaces the current subsection with @code{name}. The current
5288 section is not changed. The replaced subsection is put onto the section stack
5289 in place of the then current top of stack subsection.
5294 @section @code{.symver}
5295 @cindex @code{symver} directive
5296 @cindex symbol versioning
5297 @cindex versions of symbols
5298 Use the @code{.symver} directive to bind symbols to specific version nodes
5299 within a source file. This is only supported on ELF platforms, and is
5300 typically used when assembling files to be linked into a shared library.
5301 There are cases where it may make sense to use this in objects to be bound
5302 into an application itself so as to override a versioned symbol from a
5305 For ELF targets, the @code{.symver} directive can be used like this:
5307 .symver @var{name}, @var{name2@@nodename}
5309 If the symbol @var{name} is defined within the file
5310 being assembled, the @code{.symver} directive effectively creates a symbol
5311 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5312 just don't try and create a regular alias is that the @var{@@} character isn't
5313 permitted in symbol names. The @var{name2} part of the name is the actual name
5314 of the symbol by which it will be externally referenced. The name @var{name}
5315 itself is merely a name of convenience that is used so that it is possible to
5316 have definitions for multiple versions of a function within a single source
5317 file, and so that the compiler can unambiguously know which version of a
5318 function is being mentioned. The @var{nodename} portion of the alias should be
5319 the name of a node specified in the version script supplied to the linker when
5320 building a shared library. If you are attempting to override a versioned
5321 symbol from a shared library, then @var{nodename} should correspond to the
5322 nodename of the symbol you are trying to override.
5324 If the symbol @var{name} is not defined within the file being assembled, all
5325 references to @var{name} will be changed to @var{name2@@nodename}. If no
5326 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5329 Another usage of the @code{.symver} directive is:
5331 .symver @var{name}, @var{name2@@@@nodename}
5333 In this case, the symbol @var{name} must exist and be defined within
5334 the file being assembled. It is similar to @var{name2@@nodename}. The
5335 difference is @var{name2@@@@nodename} will also be used to resolve
5336 references to @var{name2} by the linker.
5338 The third usage of the @code{.symver} directive is:
5340 .symver @var{name}, @var{name2@@@@@@nodename}
5342 When @var{name} is not defined within the
5343 file being assembled, it is treated as @var{name2@@nodename}. When
5344 @var{name} is defined within the file being assembled, the symbol
5345 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5350 @section @code{.tag @var{structname}}
5352 @cindex COFF structure debugging
5353 @cindex structure debugging, COFF
5354 @cindex @code{tag} directive
5355 This directive is generated by compilers to include auxiliary debugging
5356 information in the symbol table. It is only permitted inside
5357 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5358 definitions in the symbol table with instances of those structures.
5361 @samp{.tag} is only used when generating COFF format output; when
5362 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5368 @section @code{.text @var{subsection}}
5370 @cindex @code{text} directive
5371 Tells @command{@value{AS}} to assemble the following statements onto the end of
5372 the text subsection numbered @var{subsection}, which is an absolute
5373 expression. If @var{subsection} is omitted, subsection number zero
5377 @section @code{.title "@var{heading}"}
5379 @cindex @code{title} directive
5380 @cindex listing control: title line
5381 Use @var{heading} as the title (second line, immediately after the
5382 source file name and pagenumber) when generating assembly listings.
5384 This directive affects subsequent pages, as well as the current page if
5385 it appears within ten lines of the top of a page.
5388 @section @code{.type @var{int}} (COFF version)
5390 @cindex COFF symbol type
5391 @cindex symbol type, COFF
5392 @cindex @code{type} directive
5393 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5394 records the integer @var{int} as the type attribute of a symbol table entry.
5397 @samp{.type} is associated only with COFF format output; when
5398 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5399 directive but ignores it.
5402 @section @code{.type @var{name} , @var{type description}} (ELF version)
5404 @cindex ELF symbol type
5405 @cindex symbol type, ELF
5406 @cindex @code{type} directive
5407 This directive is used to set the type of symbol @var{name} to be either a
5408 function symbol or an object symbol. There are five different syntaxes
5409 supported for the @var{type description} field, in order to provide
5410 compatibility with various other assemblers. The syntaxes supported are:
5413 .type <name>,#function
5414 .type <name>,#object
5416 .type <name>,@@function
5417 .type <name>,@@object
5419 .type <name>,%function
5420 .type <name>,%object
5422 .type <name>,"function"
5423 .type <name>,"object"
5425 .type <name> STT_FUNCTION
5426 .type <name> STT_OBJECT
5430 @section @code{.uleb128 @var{expressions}}
5432 @cindex @code{uleb128} directive
5433 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5434 compact, variable length representation of numbers used by the DWARF
5435 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5439 @section @code{.val @var{addr}}
5441 @cindex @code{val} directive
5442 @cindex COFF value attribute
5443 @cindex value attribute, COFF
5444 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5445 records the address @var{addr} as the value attribute of a symbol table
5449 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5450 configured for @code{b.out}, it accepts this directive but ignores it.
5456 @section @code{.version "@var{string}"}
5458 @cindex @code{.version}
5459 This directive creates a @code{.note} section and places into it an ELF
5460 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5465 @section @code{.vtable_entry @var{table}, @var{offset}}
5467 @cindex @code{.vtable_entry}
5468 This directive finds or creates a symbol @code{table} and creates a
5469 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5472 @section @code{.vtable_inherit @var{child}, @var{parent}}
5474 @cindex @code{.vtable_inherit}
5475 This directive finds the symbol @code{child} and finds or creates the symbol
5476 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5477 parent whose addend is the value of the child symbol. As a special case the
5478 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5483 @section @code{.weak @var{names}}
5485 @cindex @code{.weak}
5486 This directive sets the weak attribute on the comma separated list of symbol
5487 @code{names}. If the symbols do not already exist, they will be created.
5491 @section @code{.word @var{expressions}}
5493 @cindex @code{word} directive
5494 This directive expects zero or more @var{expressions}, of any section,
5495 separated by commas.
5498 For each expression, @command{@value{AS}} emits a 32-bit number.
5501 For each expression, @command{@value{AS}} emits a 16-bit number.
5506 The size of the number emitted, and its byte order,
5507 depend on what target computer the assembly is for.
5510 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5511 @c happen---32-bit addressability, period; no long/short jumps.
5512 @ifset DIFF-TBL-KLUGE
5513 @cindex difference tables altered
5514 @cindex altered difference tables
5516 @emph{Warning: Special Treatment to support Compilers}
5520 Machines with a 32-bit address space, but that do less than 32-bit
5521 addressing, require the following special treatment. If the machine of
5522 interest to you does 32-bit addressing (or doesn't require it;
5523 @pxref{Machine Dependencies}), you can ignore this issue.
5526 In order to assemble compiler output into something that works,
5527 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5528 Directives of the form @samp{.word sym1-sym2} are often emitted by
5529 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5530 directive of the form @samp{.word sym1-sym2}, and the difference between
5531 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5532 creates a @dfn{secondary jump table}, immediately before the next label.
5533 This secondary jump table is preceded by a short-jump to the
5534 first byte after the secondary table. This short-jump prevents the flow
5535 of control from accidentally falling into the new table. Inside the
5536 table is a long-jump to @code{sym2}. The original @samp{.word}
5537 contains @code{sym1} minus the address of the long-jump to
5540 If there were several occurrences of @samp{.word sym1-sym2} before the
5541 secondary jump table, all of them are adjusted. If there was a
5542 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5543 long-jump to @code{sym4} is included in the secondary jump table,
5544 and the @code{.word} directives are adjusted to contain @code{sym3}
5545 minus the address of the long-jump to @code{sym4}; and so on, for as many
5546 entries in the original jump table as necessary.
5549 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5550 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5551 assembly language programmers.
5554 @c end DIFF-TBL-KLUGE
5557 @section Deprecated Directives
5559 @cindex deprecated directives
5560 @cindex obsolescent directives
5561 One day these directives won't work.
5562 They are included for compatibility with older assemblers.
5569 @node Machine Dependencies
5570 @chapter Machine Dependent Features
5572 @cindex machine dependencies
5573 The machine instruction sets are (almost by definition) different on
5574 each machine where @command{@value{AS}} runs. Floating point representations
5575 vary as well, and @command{@value{AS}} often supports a few additional
5576 directives or command-line options for compatibility with other
5577 assemblers on a particular platform. Finally, some versions of
5578 @command{@value{AS}} support special pseudo-instructions for branch
5581 This chapter discusses most of these differences, though it does not
5582 include details on any machine's instruction set. For details on that
5583 subject, see the hardware manufacturer's manual.
5587 * AMD29K-Dependent:: AMD 29K Dependent Features
5590 * ARC-Dependent:: ARC Dependent Features
5593 * ARM-Dependent:: ARM Dependent Features
5596 * CRIS-Dependent:: CRIS Dependent Features
5599 * D10V-Dependent:: D10V Dependent Features
5602 * D30V-Dependent:: D30V Dependent Features
5605 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5608 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5611 * HPPA-Dependent:: HPPA Dependent Features
5614 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5617 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5620 * i860-Dependent:: Intel 80860 Dependent Features
5623 * i960-Dependent:: Intel 80960 Dependent Features
5626 * M32R-Dependent:: M32R Dependent Features
5629 * M68K-Dependent:: M680x0 Dependent Features
5632 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5635 * M88K-Dependent:: M880x0 Dependent Features
5638 * MIPS-Dependent:: MIPS Dependent Features
5641 * MMIX-Dependent:: MMIX Dependent Features
5644 * SH-Dependent:: Hitachi SH Dependent Features
5645 * SH64-Dependent:: Hitachi SH64 Dependent Features
5648 * PDP-11-Dependent:: PDP-11 Dependent Features
5651 * PJ-Dependent:: picoJava Dependent Features
5654 * PPC-Dependent:: PowerPC Dependent Features
5657 * Sparc-Dependent:: SPARC Dependent Features
5660 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5663 * V850-Dependent:: V850 Dependent Features
5666 * Z8000-Dependent:: Z8000 Dependent Features
5669 * Vax-Dependent:: VAX Dependent Features
5676 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5677 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5678 @c peculiarity: to preserve cross-references, there must be a node called
5679 @c "Machine Dependencies". Hence the conditional nodenames in each
5680 @c major node below. Node defaulting in makeinfo requires adjacency of
5681 @c node and sectioning commands; hence the repetition of @chapter BLAH
5682 @c in both conditional blocks.
5689 @include c-a29k.texi
5697 @include c-cris.texi
5702 @node Machine Dependencies
5703 @chapter Machine Dependent Features
5705 The machine instruction sets are different on each Hitachi chip family,
5706 and there are also some syntax differences among the families. This
5707 chapter describes the specific @command{@value{AS}} features for each
5711 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5712 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5713 * SH-Dependent:: Hitachi SH Dependent Features
5720 @include c-d10v.texi
5724 @include c-d30v.texi
5728 @include c-h8300.texi
5732 @include c-h8500.texi
5736 @include c-hppa.texi
5740 @include c-i370.texi
5744 @include c-i386.texi
5748 @include c-i860.texi
5752 @include c-i960.texi
5756 @include c-m32r.texi
5760 @include c-m68k.texi
5764 @include c-m68hc11.texi
5768 @include c-m88k.texi
5772 @include c-mips.texi
5776 @include c-mmix.texi
5780 @include c-ns32k.texi
5784 @include c-pdp11.texi
5797 @include c-sh64.texi
5801 @include c-sparc.texi
5805 @include c-tic54x.texi
5817 @include c-v850.texi
5821 @c reverse effect of @down at top of generic Machine-Dep chapter
5825 @node Reporting Bugs
5826 @chapter Reporting Bugs
5827 @cindex bugs in assembler
5828 @cindex reporting bugs in assembler
5830 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5832 Reporting a bug may help you by bringing a solution to your problem, or it may
5833 not. But in any case the principal function of a bug report is to help the
5834 entire community by making the next version of @command{@value{AS}} work better.
5835 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5837 In order for a bug report to serve its purpose, you must include the
5838 information that enables us to fix the bug.
5841 * Bug Criteria:: Have you found a bug?
5842 * Bug Reporting:: How to report bugs
5846 @section Have you found a bug?
5847 @cindex bug criteria
5849 If you are not sure whether you have found a bug, here are some guidelines:
5852 @cindex fatal signal
5853 @cindex assembler crash
5854 @cindex crash of assembler
5856 If the assembler gets a fatal signal, for any input whatever, that is a
5857 @command{@value{AS}} bug. Reliable assemblers never crash.
5859 @cindex error on valid input
5861 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5863 @cindex invalid input
5865 If @command{@value{AS}} does not produce an error message for invalid input, that
5866 is a bug. However, you should note that your idea of ``invalid input'' might
5867 be our idea of ``an extension'' or ``support for traditional practice''.
5870 If you are an experienced user of assemblers, your suggestions for improvement
5871 of @command{@value{AS}} are welcome in any case.
5875 @section How to report bugs
5877 @cindex assembler bugs, reporting
5879 A number of companies and individuals offer support for @sc{gnu} products. If
5880 you obtained @command{@value{AS}} from a support organization, we recommend you
5881 contact that organization first.
5883 You can find contact information for many support companies and
5884 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5887 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5888 to @samp{bug-binutils@@gnu.org}.
5890 The fundamental principle of reporting bugs usefully is this:
5891 @strong{report all the facts}. If you are not sure whether to state a
5892 fact or leave it out, state it!
5894 Often people omit facts because they think they know what causes the problem
5895 and assume that some details do not matter. Thus, you might assume that the
5896 name of a symbol you use in an example does not matter. Well, probably it does
5897 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5898 happens to fetch from the location where that name is stored in memory;
5899 perhaps, if the name were different, the contents of that location would fool
5900 the assembler into doing the right thing despite the bug. Play it safe and
5901 give a specific, complete example. That is the easiest thing for you to do,
5902 and the most helpful.
5904 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5905 it is new to us. Therefore, always write your bug reports on the assumption
5906 that the bug has not been reported previously.
5908 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5909 bell?'' Those bug reports are useless, and we urge everyone to
5910 @emph{refuse to respond to them} except to chide the sender to report
5913 To enable us to fix the bug, you should include all these things:
5917 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5918 it with the @samp{--version} argument.
5920 Without this, we will not know whether there is any point in looking for
5921 the bug in the current version of @command{@value{AS}}.
5924 Any patches you may have applied to the @command{@value{AS}} source.
5927 The type of machine you are using, and the operating system name and
5931 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5935 The command arguments you gave the assembler to assemble your example and
5936 observe the bug. To guarantee you will not omit something important, list them
5937 all. A copy of the Makefile (or the output from make) is sufficient.
5939 If we were to try to guess the arguments, we would probably guess wrong
5940 and then we might not encounter the bug.
5943 A complete input file that will reproduce the bug. If the bug is observed when
5944 the assembler is invoked via a compiler, send the assembler source, not the
5945 high level language source. Most compilers will produce the assembler source
5946 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5947 the options @samp{-v --save-temps}; this will save the assembler source in a
5948 file with an extension of @file{.s}, and also show you exactly how
5949 @command{@value{AS}} is being run.
5952 A description of what behavior you observe that you believe is
5953 incorrect. For example, ``It gets a fatal signal.''
5955 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5956 will certainly notice it. But if the bug is incorrect output, we might not
5957 notice unless it is glaringly wrong. You might as well not give us a chance to
5960 Even if the problem you experience is a fatal signal, you should still say so
5961 explicitly. Suppose something strange is going on, such as, your copy of
5962 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5963 library on your system. (This has happened!) Your copy might crash and ours
5964 would not. If you told us to expect a crash, then when ours fails to crash, we
5965 would know that the bug was not happening for us. If you had not told us to
5966 expect a crash, then we would not be able to draw any conclusion from our
5970 If you wish to suggest changes to the @command{@value{AS}} source, send us context
5971 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5972 option. Always send diffs from the old file to the new file. If you even
5973 discuss something in the @command{@value{AS}} source, refer to it by context, not
5976 The line numbers in our development sources will not match those in your
5977 sources. Your line numbers would convey no useful information to us.
5980 Here are some things that are not necessary:
5984 A description of the envelope of the bug.
5986 Often people who encounter a bug spend a lot of time investigating
5987 which changes to the input file will make the bug go away and which
5988 changes will not affect it.
5990 This is often time consuming and not very useful, because the way we
5991 will find the bug is by running a single example under the debugger
5992 with breakpoints, not by pure deduction from a series of examples.
5993 We recommend that you save your time for something else.
5995 Of course, if you can find a simpler example to report @emph{instead}
5996 of the original one, that is a convenience for us. Errors in the
5997 output will be easier to spot, running under the debugger will take
5998 less time, and so on.
6000 However, simplification is not vital; if you do not want to do this,
6001 report the bug anyway and send us the entire test case you used.
6004 A patch for the bug.
6006 A patch for the bug does help us if it is a good one. But do not omit
6007 the necessary information, such as the test case, on the assumption that
6008 a patch is all we need. We might see problems with your patch and decide
6009 to fix the problem another way, or we might not understand it at all.
6011 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6012 construct an example that will make the program follow a certain path through
6013 the code. If you do not send us the example, we will not be able to construct
6014 one, so we will not be able to verify that the bug is fixed.
6016 And if we cannot understand what bug you are trying to fix, or why your
6017 patch should be an improvement, we will not install it. A test case will
6018 help us to understand.
6021 A guess about what the bug is or what it depends on.
6023 Such guesses are usually wrong. Even we cannot guess right about such
6024 things without first using the debugger to find the facts.
6027 @node Acknowledgements
6028 @chapter Acknowledgements
6030 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6031 it is not meant as a slight. We just don't know about it. Send mail to the
6032 maintainer, and we'll correct the situation. Currently
6034 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6036 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6039 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6040 information and the 68k series machines, most of the preprocessing pass, and
6041 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6043 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6044 many bug fixes, including merging support for several processors, breaking GAS
6045 up to handle multiple object file format back ends (including heavy rewrite,
6046 testing, an integration of the coff and b.out back ends), adding configuration
6047 including heavy testing and verification of cross assemblers and file splits
6048 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6049 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6050 port (including considerable amounts of reverse engineering), a SPARC opcode
6051 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6052 assertions and made them work, much other reorganization, cleanup, and lint.
6054 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6055 in format-specific I/O modules.
6057 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6058 has done much work with it since.
6060 The Intel 80386 machine description was written by Eliot Dresselhaus.
6062 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6064 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6065 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6067 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6068 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6069 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6070 support a.out format.
6072 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6073 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6074 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6075 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6078 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6079 simplified the configuration of which versions accept which directives. He
6080 updated the 68k machine description so that Motorola's opcodes always produced
6081 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6082 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6083 cross-compilation support, and one bug in relaxation that took a week and
6084 required the proverbial one-bit fix.
6086 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6087 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6088 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6089 PowerPC assembler, and made a few other minor patches.
6091 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6093 Hewlett-Packard contributed support for the HP9000/300.
6095 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6096 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6097 formats). This work was supported by both the Center for Software Science at
6098 the University of Utah and Cygnus Support.
6100 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6101 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6102 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6103 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6104 and some initial 64-bit support).
6106 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6108 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6109 support for openVMS/Alpha.
6111 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6114 Several engineers at Cygnus Support have also provided many small bug fixes and
6115 configuration enhancements.
6117 Many others have contributed large or small bugfixes and enhancements. If
6118 you have contributed significant work and are not mentioned on this list, and
6119 want to be, let us know. Some of the history has been lost; we are not
6120 intentionally leaving anyone out.
6122 @node GNU Free Documentation License
6123 @chapter GNU Free Documentation License
6125 GNU Free Documentation License
6127 Version 1.1, March 2000
6129 Copyright (C) 2000 Free Software Foundation, Inc.
6130 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6132 Everyone is permitted to copy and distribute verbatim copies
6133 of this license document, but changing it is not allowed.
6138 The purpose of this License is to make a manual, textbook, or other
6139 written document "free" in the sense of freedom: to assure everyone
6140 the effective freedom to copy and redistribute it, with or without
6141 modifying it, either commercially or noncommercially. Secondarily,
6142 this License preserves for the author and publisher a way to get
6143 credit for their work, while not being considered responsible for
6144 modifications made by others.
6146 This License is a kind of "copyleft", which means that derivative
6147 works of the document must themselves be free in the same sense. It
6148 complements the GNU General Public License, which is a copyleft
6149 license designed for free software.
6151 We have designed this License in order to use it for manuals for free
6152 software, because free software needs free documentation: a free
6153 program should come with manuals providing the same freedoms that the
6154 software does. But this License is not limited to software manuals;
6155 it can be used for any textual work, regardless of subject matter or
6156 whether it is published as a printed book. We recommend this License
6157 principally for works whose purpose is instruction or reference.
6160 1. APPLICABILITY AND DEFINITIONS
6162 This License applies to any manual or other work that contains a
6163 notice placed by the copyright holder saying it can be distributed
6164 under the terms of this License. The "Document", below, refers to any
6165 such manual or work. Any member of the public is a licensee, and is
6168 A "Modified Version" of the Document means any work containing the
6169 Document or a portion of it, either copied verbatim, or with
6170 modifications and/or translated into another language.
6172 A "Secondary Section" is a named appendix or a front-matter section of
6173 the Document that deals exclusively with the relationship of the
6174 publishers or authors of the Document to the Document's overall subject
6175 (or to related matters) and contains nothing that could fall directly
6176 within that overall subject. (For example, if the Document is in part a
6177 textbook of mathematics, a Secondary Section may not explain any
6178 mathematics.) The relationship could be a matter of historical
6179 connection with the subject or with related matters, or of legal,
6180 commercial, philosophical, ethical or political position regarding
6183 The "Invariant Sections" are certain Secondary Sections whose titles
6184 are designated, as being those of Invariant Sections, in the notice
6185 that says that the Document is released under this License.
6187 The "Cover Texts" are certain short passages of text that are listed,
6188 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6189 the Document is released under this License.
6191 A "Transparent" copy of the Document means a machine-readable copy,
6192 represented in a format whose specification is available to the
6193 general public, whose contents can be viewed and edited directly and
6194 straightforwardly with generic text editors or (for images composed of
6195 pixels) generic paint programs or (for drawings) some widely available
6196 drawing editor, and that is suitable for input to text formatters or
6197 for automatic translation to a variety of formats suitable for input
6198 to text formatters. A copy made in an otherwise Transparent file
6199 format whose markup has been designed to thwart or discourage
6200 subsequent modification by readers is not Transparent. A copy that is
6201 not "Transparent" is called "Opaque".
6203 Examples of suitable formats for Transparent copies include plain
6204 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6205 or XML using a publicly available DTD, and standard-conforming simple
6206 HTML designed for human modification. Opaque formats include
6207 PostScript, PDF, proprietary formats that can be read and edited only
6208 by proprietary word processors, SGML or XML for which the DTD and/or
6209 processing tools are not generally available, and the
6210 machine-generated HTML produced by some word processors for output
6213 The "Title Page" means, for a printed book, the title page itself,
6214 plus such following pages as are needed to hold, legibly, the material
6215 this License requires to appear in the title page. For works in
6216 formats which do not have any title page as such, "Title Page" means
6217 the text near the most prominent appearance of the work's title,
6218 preceding the beginning of the body of the text.
6223 You may copy and distribute the Document in any medium, either
6224 commercially or noncommercially, provided that this License, the
6225 copyright notices, and the license notice saying this License applies
6226 to the Document are reproduced in all copies, and that you add no other
6227 conditions whatsoever to those of this License. You may not use
6228 technical measures to obstruct or control the reading or further
6229 copying of the copies you make or distribute. However, you may accept
6230 compensation in exchange for copies. If you distribute a large enough
6231 number of copies you must also follow the conditions in section 3.
6233 You may also lend copies, under the same conditions stated above, and
6234 you may publicly display copies.
6237 3. COPYING IN QUANTITY
6239 If you publish printed copies of the Document numbering more than 100,
6240 and the Document's license notice requires Cover Texts, you must enclose
6241 the copies in covers that carry, clearly and legibly, all these Cover
6242 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6243 the back cover. Both covers must also clearly and legibly identify
6244 you as the publisher of these copies. The front cover must present
6245 the full title with all words of the title equally prominent and
6246 visible. You may add other material on the covers in addition.
6247 Copying with changes limited to the covers, as long as they preserve
6248 the title of the Document and satisfy these conditions, can be treated
6249 as verbatim copying in other respects.
6251 If the required texts for either cover are too voluminous to fit
6252 legibly, you should put the first ones listed (as many as fit
6253 reasonably) on the actual cover, and continue the rest onto adjacent
6256 If you publish or distribute Opaque copies of the Document numbering
6257 more than 100, you must either include a machine-readable Transparent
6258 copy along with each Opaque copy, or state in or with each Opaque copy
6259 a publicly-accessible computer-network location containing a complete
6260 Transparent copy of the Document, free of added material, which the
6261 general network-using public has access to download anonymously at no
6262 charge using public-standard network protocols. If you use the latter
6263 option, you must take reasonably prudent steps, when you begin
6264 distribution of Opaque copies in quantity, to ensure that this
6265 Transparent copy will remain thus accessible at the stated location
6266 until at least one year after the last time you distribute an Opaque
6267 copy (directly or through your agents or retailers) of that edition to
6270 It is requested, but not required, that you contact the authors of the
6271 Document well before redistributing any large number of copies, to give
6272 them a chance to provide you with an updated version of the Document.
6277 You may copy and distribute a Modified Version of the Document under
6278 the conditions of sections 2 and 3 above, provided that you release
6279 the Modified Version under precisely this License, with the Modified
6280 Version filling the role of the Document, thus licensing distribution
6281 and modification of the Modified Version to whoever possesses a copy
6282 of it. In addition, you must do these things in the Modified Version:
6284 A. Use in the Title Page (and on the covers, if any) a title distinct
6285 from that of the Document, and from those of previous versions
6286 (which should, if there were any, be listed in the History section
6287 of the Document). You may use the same title as a previous version
6288 if the original publisher of that version gives permission.
6289 B. List on the Title Page, as authors, one or more persons or entities
6290 responsible for authorship of the modifications in the Modified
6291 Version, together with at least five of the principal authors of the
6292 Document (all of its principal authors, if it has less than five).
6293 C. State on the Title page the name of the publisher of the
6294 Modified Version, as the publisher.
6295 D. Preserve all the copyright notices of the Document.
6296 E. Add an appropriate copyright notice for your modifications
6297 adjacent to the other copyright notices.
6298 F. Include, immediately after the copyright notices, a license notice
6299 giving the public permission to use the Modified Version under the
6300 terms of this License, in the form shown in the Addendum below.
6301 G. Preserve in that license notice the full lists of Invariant Sections
6302 and required Cover Texts given in the Document's license notice.
6303 H. Include an unaltered copy of this License.
6304 I. Preserve the section entitled "History", and its title, and add to
6305 it an item stating at least the title, year, new authors, and
6306 publisher of the Modified Version as given on the Title Page. If
6307 there is no section entitled "History" in the Document, create one
6308 stating the title, year, authors, and publisher of the Document as
6309 given on its Title Page, then add an item describing the Modified
6310 Version as stated in the previous sentence.
6311 J. Preserve the network location, if any, given in the Document for
6312 public access to a Transparent copy of the Document, and likewise
6313 the network locations given in the Document for previous versions
6314 it was based on. These may be placed in the "History" section.
6315 You may omit a network location for a work that was published at
6316 least four years before the Document itself, or if the original
6317 publisher of the version it refers to gives permission.
6318 K. In any section entitled "Acknowledgements" or "Dedications",
6319 preserve the section's title, and preserve in the section all the
6320 substance and tone of each of the contributor acknowledgements
6321 and/or dedications given therein.
6322 L. Preserve all the Invariant Sections of the Document,
6323 unaltered in their text and in their titles. Section numbers
6324 or the equivalent are not considered part of the section titles.
6325 M. Delete any section entitled "Endorsements". Such a section
6326 may not be included in the Modified Version.
6327 N. Do not retitle any existing section as "Endorsements"
6328 or to conflict in title with any Invariant Section.
6330 If the Modified Version includes new front-matter sections or
6331 appendices that qualify as Secondary Sections and contain no material
6332 copied from the Document, you may at your option designate some or all
6333 of these sections as invariant. To do this, add their titles to the
6334 list of Invariant Sections in the Modified Version's license notice.
6335 These titles must be distinct from any other section titles.
6337 You may add a section entitled "Endorsements", provided it contains
6338 nothing but endorsements of your Modified Version by various
6339 parties--for example, statements of peer review or that the text has
6340 been approved by an organization as the authoritative definition of a
6343 You may add a passage of up to five words as a Front-Cover Text, and a
6344 passage of up to 25 words as a Back-Cover Text, to the end of the list
6345 of Cover Texts in the Modified Version. Only one passage of
6346 Front-Cover Text and one of Back-Cover Text may be added by (or
6347 through arrangements made by) any one entity. If the Document already
6348 includes a cover text for the same cover, previously added by you or
6349 by arrangement made by the same entity you are acting on behalf of,
6350 you may not add another; but you may replace the old one, on explicit
6351 permission from the previous publisher that added the old one.
6353 The author(s) and publisher(s) of the Document do not by this License
6354 give permission to use their names for publicity for or to assert or
6355 imply endorsement of any Modified Version.
6358 5. COMBINING DOCUMENTS
6360 You may combine the Document with other documents released under this
6361 License, under the terms defined in section 4 above for modified
6362 versions, provided that you include in the combination all of the
6363 Invariant Sections of all of the original documents, unmodified, and
6364 list them all as Invariant Sections of your combined work in its
6367 The combined work need only contain one copy of this License, and
6368 multiple identical Invariant Sections may be replaced with a single
6369 copy. If there are multiple Invariant Sections with the same name but
6370 different contents, make the title of each such section unique by
6371 adding at the end of it, in parentheses, the name of the original
6372 author or publisher of that section if known, or else a unique number.
6373 Make the same adjustment to the section titles in the list of
6374 Invariant Sections in the license notice of the combined work.
6376 In the combination, you must combine any sections entitled "History"
6377 in the various original documents, forming one section entitled
6378 "History"; likewise combine any sections entitled "Acknowledgements",
6379 and any sections entitled "Dedications". You must delete all sections
6380 entitled "Endorsements."
6383 6. COLLECTIONS OF DOCUMENTS
6385 You may make a collection consisting of the Document and other documents
6386 released under this License, and replace the individual copies of this
6387 License in the various documents with a single copy that is included in
6388 the collection, provided that you follow the rules of this License for
6389 verbatim copying of each of the documents in all other respects.
6391 You may extract a single document from such a collection, and distribute
6392 it individually under this License, provided you insert a copy of this
6393 License into the extracted document, and follow this License in all
6394 other respects regarding verbatim copying of that document.
6397 7. AGGREGATION WITH INDEPENDENT WORKS
6399 A compilation of the Document or its derivatives with other separate
6400 and independent documents or works, in or on a volume of a storage or
6401 distribution medium, does not as a whole count as a Modified Version
6402 of the Document, provided no compilation copyright is claimed for the
6403 compilation. Such a compilation is called an "aggregate", and this
6404 License does not apply to the other self-contained works thus compiled
6405 with the Document, on account of their being thus compiled, if they
6406 are not themselves derivative works of the Document.
6408 If the Cover Text requirement of section 3 is applicable to these
6409 copies of the Document, then if the Document is less than one quarter
6410 of the entire aggregate, the Document's Cover Texts may be placed on
6411 covers that surround only the Document within the aggregate.
6412 Otherwise they must appear on covers around the whole aggregate.
6417 Translation is considered a kind of modification, so you may
6418 distribute translations of the Document under the terms of section 4.
6419 Replacing Invariant Sections with translations requires special
6420 permission from their copyright holders, but you may include
6421 translations of some or all Invariant Sections in addition to the
6422 original versions of these Invariant Sections. You may include a
6423 translation of this License provided that you also include the
6424 original English version of this License. In case of a disagreement
6425 between the translation and the original English version of this
6426 License, the original English version will prevail.
6431 You may not copy, modify, sublicense, or distribute the Document except
6432 as expressly provided for under this License. Any other attempt to
6433 copy, modify, sublicense or distribute the Document is void, and will
6434 automatically terminate your rights under this License. However,
6435 parties who have received copies, or rights, from you under this
6436 License will not have their licenses terminated so long as such
6437 parties remain in full compliance.
6440 10. FUTURE REVISIONS OF THIS LICENSE
6442 The Free Software Foundation may publish new, revised versions
6443 of the GNU Free Documentation License from time to time. Such new
6444 versions will be similar in spirit to the present version, but may
6445 differ in detail to address new problems or concerns. See
6446 http://www.gnu.org/copyleft/.
6448 Each version of the License is given a distinguishing version number.
6449 If the Document specifies that a particular numbered version of this
6450 License "or any later version" applies to it, you have the option of
6451 following the terms and conditions either of that specified version or
6452 of any later version that has been published (not as a draft) by the
6453 Free Software Foundation. If the Document does not specify a version
6454 number of this License, you may choose any version ever published (not
6455 as a draft) by the Free Software Foundation.
6458 ADDENDUM: How to use this License for your documents
6460 To use this License in a document you have written, include a copy of
6461 the License in the document and put the following copyright and
6462 license notices just after the title page:
6465 Copyright (c) YEAR YOUR NAME.
6466 Permission is granted to copy, distribute and/or modify this document
6467 under the terms of the GNU Free Documentation License, Version 1.1
6468 or any later version published by the Free Software Foundation;
6469 with the Invariant Sections being LIST THEIR TITLES, with the
6470 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6471 A copy of the license is included in the section entitled "GNU
6472 Free Documentation License".
6475 If you have no Invariant Sections, write "with no Invariant Sections"
6476 instead of saying which ones are invariant. If you have no
6477 Front-Cover Texts, write "no Front-Cover Texts" instead of
6478 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6480 If your document contains nontrivial examples of program code, we
6481 recommend releasing these examples in parallel under your choice of
6482 free software license, such as the GNU General Public License,
6483 to permit their use in free software.
projects / deliverable / binutils-gdb.git / blob