1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
4 @c Free Software Foundation, Inc.
5 @c UPDATE!! On future updates--
6 @c (1) check for new machine-dep cmdline options in
7 @c md_parse_option definitions in config/tc-*.c
8 @c (2) for platform-specific directives, examine md_pseudo_op
10 @c (3) for object-format specific directives, examine obj_pseudo_op
12 @c (4) portable directives in potable[] in read.c
16 @macro gcctabopt{body}
19 @c defaults, config file may override:
22 @include asconfig.texi
27 @c Configure for the generation of man pages
63 @c common OR combinations of conditions
83 @set abnormal-separator
87 @settitle Using @value{AS}
90 @settitle Using @value{AS} (@value{TARGET})
92 @setchapternewpage odd
97 @c WARE! Some of the machine-dependent sections contain tables of machine
98 @c instructions. Except in multi-column format, these tables look silly.
99 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
100 @c the multi-col format is faked within @example sections.
102 @c Again unfortunately, the natural size that fits on a page, for these tables,
103 @c is different depending on whether or not smallbook is turned on.
104 @c This matters, because of order: text flow switches columns at each page
107 @c The format faked in this source works reasonably well for smallbook,
108 @c not well for the default large-page format. This manual expects that if you
109 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
110 @c tables in question. You can turn on one without the other at your
111 @c discretion, of course.
114 @c the insn tables look just as silly in info files regardless of smallbook,
115 @c might as well show 'em anyways.
121 * As: (as). The GNU assembler.
122 * Gas: (as). The GNU assembler.
131 This file documents the GNU Assembler "@value{AS}".
133 @c man begin COPYRIGHT
134 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
136 Permission is granted to copy, distribute and/or modify this document
137 under the terms of the GNU Free Documentation License, Version 1.1
138 or any later version published by the Free Software Foundation;
139 with no Invariant Sections, with no Front-Cover Texts, and with no
140 Back-Cover Texts. A copy of the license is included in the
141 section entitled "GNU Free Documentation License".
146 Permission is granted to process this file through Tex and print the
147 results, provided the printed document carries copying permission
148 notice identical to this one except for the removal of this paragraph
149 (this paragraph not being relevant to the printed manual).
155 @title Using @value{AS}
156 @subtitle The @sc{gnu} Assembler
158 @subtitle for the @value{TARGET} family
161 @subtitle Version @value{VERSION}
164 The Free Software Foundation Inc. thanks The Nice Computer
165 Company of Australia for loaning Dean Elsner to write the
166 first (Vax) version of @command{as} for Project @sc{gnu}.
167 The proprietors, management and staff of TNCCA thank FSF for
168 distracting the boss while they got some work
171 @author Dean Elsner, Jay Fenlason & friends
175 \hfill {\it Using {\tt @value{AS}}}\par
176 \hfill Edited by Cygnus Support\par
178 %"boxit" macro for figures:
179 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
180 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
181 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
182 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
183 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
186 @vskip 0pt plus 1filll
187 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
189 Permission is granted to copy, distribute and/or modify this document
190 under the terms of the GNU Free Documentation License, Version 1.1
191 or any later version published by the Free Software Foundation;
192 with no Invariant Sections, with no Front-Cover Texts, and with no
193 Back-Cover Texts. A copy of the license is included in the
194 section entitled "GNU Free Documentation License".
200 @top Using @value{AS}
202 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
205 This version of the file describes @command{@value{AS}} configured to generate
206 code for @value{TARGET} architectures.
209 This document is distributed under the terms of the GNU Free
210 Documentation License. A copy of the license is included in the
211 section entitled "GNU Free Documentation License".
214 * Overview:: Overview
215 * Invoking:: Command-Line Options
217 * Sections:: Sections and Relocation
219 * Expressions:: Expressions
220 * Pseudo Ops:: Assembler Directives
221 * Machine Dependencies:: Machine Dependent Features
222 * Reporting Bugs:: Reporting Bugs
223 * Acknowledgements:: Who Did What
224 * GNU Free Documentation License:: GNU Free Documentation License
232 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
234 This version of the manual describes @command{@value{AS}} configured to generate
235 code for @value{TARGET} architectures.
239 @cindex invocation summary
240 @cindex option summary
241 @cindex summary of options
242 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
243 @pxref{Invoking,,Comand-Line Options}.
245 @c man title AS the portable GNU assembler.
249 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
253 @c We don't use deffn and friends for the following because they seem
254 @c to be limited to one line for the header.
256 @c man begin SYNOPSIS
257 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
258 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
259 [@b{-J}] [@b{-K}] [@b{-L}]
260 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
261 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
262 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
263 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
264 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
265 [@b{--}|@var{files} @dots{}]
267 @c Target dependent options are listed below. Keep the list sorted.
268 @c Add an empty line for separation.
270 @c am29k has no machine-dependent assembler options
274 @emph{Target Alpha options:}
276 [@b{-mdebug} | @b{-no-mdebug}]
277 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
278 [@b{-F}] [@b{-32addr}]
282 @emph{Target ARC options:}
288 @emph{Target ARM options:}
289 @c Don't document the deprecated options
290 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
291 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
292 [@b{-mfpu}=@var{floating-point-fromat}]
295 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
296 @b{-mapcs-reentrant}]
297 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
301 @emph{Target CRIS options:}
302 [@b{--underscore} | @b{--no-underscore}]
304 [@b{--emulation=criself} | @b{--emulation=crisaout}]
305 @c Deprecated -- deliberately not documented.
310 @emph{Target D10V options:}
315 @emph{Target D30V options:}
316 [@b{-O}|@b{-n}|@b{-N}]
319 @c Hitachi family chips have no machine-dependent assembler options
322 @c HPPA has no machine-dependent assembler options (yet).
326 @emph{Target i386 options:}
331 @emph{Target i960 options:}
332 @c see md_parse_option in tc-i960.c
333 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
335 [@b{-b}] [@b{-no-relax}]
339 @emph{Target IA-64 options:}
340 [@b{-mconstant-gp}|@b{-mauto-pic}]
341 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
343 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
346 @emph{Target M32R options:}
347 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
352 @emph{Target M680X0 options:}
353 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
357 @emph{Target M68HC11 options:}
358 [@b{-m68hc11}|@b{-m68hc12}]
359 [@b{--force-long-branchs}] [@b{--short-branchs}]
360 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
361 [@b{--print-opcodes}] [@b{--generate-example}]
365 @emph{Target MCORE options:}
366 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
367 [@b{-mcpu=[210|340]}]
371 @emph{Target MIPS options:}
372 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
373 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
374 [@b{-mips32}] [@b{-mips64}]
375 [@b{-m4650}] [@b{-no-m4650}]
376 [@b{--trap}] [@b{--break}] [@b{-n}]
377 [@b{--emulation}=@var{name} ]
381 @emph{Target MMIX options:}
382 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
383 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
384 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
385 [@b{--linker-allocated-gregs}]
389 @emph{Target PDP11 options:}
390 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
391 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
392 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
396 @emph{Target picoJava options:}
401 @emph{Target PowerPC options:}
402 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
403 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
404 @b{-mbooke32}|@b{-mbooke64}]
405 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
406 [@b{-mregnames}|@b{-mno-regnames}]
407 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
408 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
409 [@b{-msolaris}|@b{-mno-solaris}]
413 @emph{Target SPARC options:}
414 @c The order here is important. See c-sparc.texi.
415 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
416 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
417 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
422 @emph{Target TIC54X options:}
423 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
424 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
427 @c Z8000 has no machine-dependent assembler options
436 Turn on listings, in any of a variety of ways:
440 omit false conditionals
443 omit debugging directives
446 include high-level source
452 include macro expansions
455 omit forms processing
461 set the name of the listing file
464 You may combine these options; for example, use @samp{-aln} for assembly
465 listing without forms processing. The @samp{=file} option, if used, must be
466 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
469 Ignored. This option is accepted for script compatibility with calls to
472 @item --defsym @var{sym}=@var{value}
473 Define the symbol @var{sym} to be @var{value} before assembling the input file.
474 @var{value} must be an integer constant. As in C, a leading @samp{0x}
475 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
478 ``fast''---skip whitespace and comment preprocessing (assume source is
482 Generate stabs debugging information for each assembler line. This
483 may help debugging assembler code, if the debugger can handle it.
486 Generate DWARF2 debugging information for each assembler line. This
487 may help debugging assembler code, if the debugger can handle it. Note - this
488 option is only supported by some targets, not all of them.
491 Print a summary of the command line options and exit.
494 Print a summary of all target specific options and exit.
497 Add directory @var{dir} to the search list for @code{.include} directives.
500 Don't warn about signed overflow.
503 @ifclear DIFF-TBL-KLUGE
504 This option is accepted but has no effect on the @value{TARGET} family.
506 @ifset DIFF-TBL-KLUGE
507 Issue warnings when difference tables altered for long displacements.
512 Keep (in the symbol table) local symbols. On traditional a.out systems
513 these start with @samp{L}, but different systems have different local
516 @item --listing-lhs-width=@var{number}
517 Set the maximum width, in words, of the output data column for an assembler
518 listing to @var{number}.
520 @item --listing-lhs-width2=@var{number}
521 Set the maximum width, in words, of the output data column for continuation
522 lines in an assembler listing to @var{number}.
524 @item --listing-rhs-width=@var{number}
525 Set the maximum width of an input source line, as displayed in a listing, to
528 @item --listing-cont-lines=@var{number}
529 Set the maximum number of lines printed in a listing for a single line of input
532 @item -o @var{objfile}
533 Name the object-file output from @command{@value{AS}} @var{objfile}.
536 Fold the data section into the text section.
539 Print the maximum space (in bytes) and total time (in seconds) used by
542 @item --strip-local-absolute
543 Remove local absolute symbols from the outgoing symbol table.
547 Print the @command{as} version.
550 Print the @command{as} version and exit.
554 Suppress warning messages.
556 @item --fatal-warnings
557 Treat warnings as errors.
560 Don't suppress warning messages or treat them as errors.
569 Generate an object file even after errors.
571 @item -- | @var{files} @dots{}
572 Standard input, or source files to assemble.
577 The following options are available when @value{AS} is configured for
582 This option selects the core processor variant.
584 Select either big-endian (-EB) or little-endian (-EL) output.
589 The following options are available when @value{AS} is configured for the ARM
593 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
594 Specify which ARM processor variant is the target.
595 @item -march=@var{architecture}[+@var{extension}@dots{}]
596 Specify which ARM architecture variant is used by the target.
597 @item -mfpu=@var{floating-point-format}
598 Select which Floating Point architecture is the target.
600 Enable Thumb only instruction decoding.
601 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
602 Select which procedure calling convention is in use.
604 Select either big-endian (-EB) or little-endian (-EL) output.
605 @item -mthumb-interwork
606 Specify that the code has been generated with interworking between Thumb and
609 Specify that PIC code has been generated.
614 See the info pages for documentation of the CRIS-specific options.
618 The following options are available when @value{AS} is configured for
621 @cindex D10V optimization
622 @cindex optimization, D10V
624 Optimize output by parallelizing instructions.
629 The following options are available when @value{AS} is configured for a D30V
632 @cindex D30V optimization
633 @cindex optimization, D30V
635 Optimize output by parallelizing instructions.
639 Warn when nops are generated.
641 @cindex D30V nops after 32-bit multiply
643 Warn when a nop after a 32-bit multiply instruction is generated.
648 The following options are available when @value{AS} is configured for the
649 Intel 80960 processor.
652 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
653 Specify which variant of the 960 architecture is the target.
656 Add code to collect statistics about branches taken.
659 Do not alter compare-and-branch instructions for long displacements;
666 The following options are available when @value{AS} is configured for the
667 Mitsubishi M32R series.
672 Specify which processor in the M32R family is the target. The default
673 is normally the M32R, but this option changes it to the M32RX.
675 @item --warn-explicit-parallel-conflicts or --Wp
676 Produce warning messages when questionable parallel constructs are
679 @item --no-warn-explicit-parallel-conflicts or --Wnp
680 Do not produce warning messages when questionable parallel constructs are
687 The following options are available when @value{AS} is configured for the
688 Motorola 68000 series.
693 Shorten references to undefined symbols, to one word instead of two.
695 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
696 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
697 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
698 Specify what processor in the 68000 family is the target. The default
699 is normally the 68020, but this can be changed at configuration time.
701 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
702 The target machine does (or does not) have a floating-point coprocessor.
703 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
704 the basic 68000 is not compatible with the 68881, a combination of the
705 two can be specified, since it's possible to do emulation of the
706 coprocessor instructions with the main processor.
708 @item -m68851 | -mno-68851
709 The target machine does (or does not) have a memory-management
710 unit coprocessor. The default is to assume an MMU for 68020 and up.
717 For details about the PDP-11 machine dependent features options,
718 see @ref{PDP-11-Options}.
721 @item -mpic | -mno-pic
722 Generate position-independent (or position-dependent) code. The
723 default is @option{-mpic}.
726 @itemx -mall-extensions
727 Enable all instruction set extensions. This is the default.
729 @item -mno-extensions
730 Disable all instruction set extensions.
732 @item -m@var{extension} | -mno-@var{extension}
733 Enable (or disable) a particular instruction set extension.
736 Enable the instruction set extensions supported by a particular CPU, and
737 disable all other extensions.
739 @item -m@var{machine}
740 Enable the instruction set extensions supported by a particular machine
741 model, and disable all other extensions.
747 The following options are available when @value{AS} is configured for
748 a picoJava processor.
752 @cindex PJ endianness
753 @cindex endianness, PJ
754 @cindex big endian output, PJ
756 Generate ``big endian'' format output.
758 @cindex little endian output, PJ
760 Generate ``little endian'' format output.
766 The following options are available when @value{AS} is configured for the
767 Motorola 68HC11 or 68HC12 series.
771 @item -m68hc11 | -m68hc12
772 Specify what processor is the target. The default is
773 defined by the configuration option when building the assembler.
775 @item --force-long-branchs
776 Relative branches are turned into absolute ones. This concerns
777 conditional branches, unconditional branches and branches to a
780 @item -S | --short-branchs
781 Do not turn relative branchs into absolute ones
782 when the offset is out of range.
784 @item --strict-direct-mode
785 Do not turn the direct addressing mode into extended addressing mode
786 when the instruction does not support direct addressing mode.
788 @item --print-insn-syntax
789 Print the syntax of instruction in case of error.
791 @item --print-opcodes
792 print the list of instructions with syntax and then exit.
794 @item --generate-example
795 print an example of instruction for each possible instruction and then exit.
796 This option is only useful for testing @command{@value{AS}}.
802 The following options are available when @command{@value{AS}} is configured
803 for the SPARC architecture:
806 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
807 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
808 Explicitly select a variant of the SPARC architecture.
810 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
811 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
813 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
814 UltraSPARC extensions.
816 @item -xarch=v8plus | -xarch=v8plusa
817 For compatibility with the Solaris v9 assembler. These options are
818 equivalent to -Av8plus and -Av8plusa, respectively.
821 Warn when the assembler switches to another architecture.
826 The following options are available when @value{AS} is configured for the 'c54x
831 Enable extended addressing mode. All addresses and relocations will assume
832 extended addressing (usually 23 bits).
833 @item -mcpu=@var{CPU_VERSION}
834 Sets the CPU version being compiled for.
835 @item -merrors-to-file @var{FILENAME}
836 Redirect error output to a file, for broken systems which don't support such
837 behaviour in the shell.
842 The following options are available when @value{AS} is configured for
847 This option sets the largest size of an object that can be referenced
848 implicitly with the @code{gp} register. It is only accepted for targets that
849 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
851 @cindex MIPS endianness
852 @cindex endianness, MIPS
853 @cindex big endian output, MIPS
855 Generate ``big endian'' format output.
857 @cindex little endian output, MIPS
859 Generate ``little endian'' format output.
868 Generate code for a particular MIPS Instruction Set Architecture level.
869 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
870 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
872 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
873 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
874 processors, respectively.
878 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
879 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
880 instructions around accesses to the @samp{HI} and @samp{LO} registers.
881 @samp{-no-m4650} turns off this option.
883 @item -mcpu=@var{CPU}
884 Generate code for a particular MIPS cpu. It is exactly equivalent to
885 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
889 @item --emulation=@var{name}
890 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
891 for some other target, in all respects, including output format (choosing
892 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
893 debugging information or store symbol table information, and default
894 endianness. The available configuration names are: @samp{mipsecoff},
895 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
896 @samp{mipsbelf}. The first two do not alter the default endianness from that
897 of the primary target for which the assembler was configured; the others change
898 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
899 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
900 selection in any case.
902 This option is currently supported only when the primary target
903 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
904 Furthermore, the primary target or others specified with
905 @samp{--enable-targets=@dots{}} at configuration time must include support for
906 the other format, if both are to be available. For example, the Irix 5
907 configuration includes support for both.
909 Eventually, this option will support more configurations, with more
910 fine-grained control over the assembler's behavior, and will be supported for
914 @command{@value{AS}} ignores this option. It is accepted for compatibility with
922 Control how to deal with multiplication overflow and division by zero.
923 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
924 (and only work for Instruction Set Architecture level 2 and higher);
925 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
929 When this option is used, @command{@value{AS}} will issue a warning every
930 time it generates a nop instruction from a macro.
935 The following options are available when @value{AS} is configured for
941 Enable or disable the JSRI to BSR transformation. By default this is enabled.
942 The command line option @samp{-nojsri2bsr} can be used to disable it.
946 Enable or disable the silicon filter behaviour. By default this is disabled.
947 The default can be overridden by the @samp{-sifilter} command line option.
950 Alter jump instructions for long displacements.
952 @item -mcpu=[210|340]
953 Select the cpu type on the target hardware. This controls which instructions
957 Assemble for a big endian target.
960 Assemble for a little endian target.
966 See the info pages for documentation of the MMIX-specific options.
972 * Manual:: Structure of this Manual
973 * GNU Assembler:: The GNU Assembler
974 * Object Formats:: Object File Formats
975 * Command Line:: Command Line
976 * Input Files:: Input Files
977 * Object:: Output (Object) File
978 * Errors:: Error and Warning Messages
982 @section Structure of this Manual
984 @cindex manual, structure and purpose
985 This manual is intended to describe what you need to know to use
986 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
987 notation for symbols, constants, and expressions; the directives that
988 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
991 We also cover special features in the @value{TARGET}
992 configuration of @command{@value{AS}}, including assembler directives.
995 This manual also describes some of the machine-dependent features of
996 various flavors of the assembler.
999 @cindex machine instructions (not covered)
1000 On the other hand, this manual is @emph{not} intended as an introduction
1001 to programming in assembly language---let alone programming in general!
1002 In a similar vein, we make no attempt to introduce the machine
1003 architecture; we do @emph{not} describe the instruction set, standard
1004 mnemonics, registers or addressing modes that are standard to a
1005 particular architecture.
1007 You may want to consult the manufacturer's
1008 machine architecture manual for this information.
1012 For information on the H8/300 machine instruction set, see @cite{H8/300
1013 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1014 see @cite{H8/300H Series Programming Manual} (Hitachi).
1017 For information on the H8/500 machine instruction set, see @cite{H8/500
1018 Series Programming Manual} (Hitachi M21T001).
1021 For information on the Hitachi SH machine instruction set, see
1022 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1025 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1029 @c I think this is premature---doc@cygnus.com, 17jan1991
1031 Throughout this manual, we assume that you are running @dfn{GNU},
1032 the portable operating system from the @dfn{Free Software
1033 Foundation, Inc.}. This restricts our attention to certain kinds of
1034 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1035 once this assumption is granted examples and definitions need less
1038 @command{@value{AS}} is part of a team of programs that turn a high-level
1039 human-readable series of instructions into a low-level
1040 computer-readable series of instructions. Different versions of
1041 @command{@value{AS}} are used for different kinds of computer.
1044 @c There used to be a section "Terminology" here, which defined
1045 @c "contents", "byte", "word", and "long". Defining "word" to any
1046 @c particular size is confusing when the .word directive may generate 16
1047 @c bits on one machine and 32 bits on another; in general, for the user
1048 @c version of this manual, none of these terms seem essential to define.
1049 @c They were used very little even in the former draft of the manual;
1050 @c this draft makes an effort to avoid them (except in names of
1054 @section The GNU Assembler
1056 @c man begin DESCRIPTION
1058 @sc{gnu} @command{as} is really a family of assemblers.
1060 This manual describes @command{@value{AS}}, a member of that family which is
1061 configured for the @value{TARGET} architectures.
1063 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1064 should find a fairly similar environment when you use it on another
1065 architecture. Each version has much in common with the others,
1066 including object file formats, most assembler directives (often called
1067 @dfn{pseudo-ops}) and assembler syntax.@refill
1069 @cindex purpose of @sc{gnu} assembler
1070 @command{@value{AS}} is primarily intended to assemble the output of the
1071 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1072 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1073 assemble correctly everything that other assemblers for the same
1074 machine would assemble.
1076 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1079 @c This remark should appear in generic version of manual; assumption
1080 @c here is that generic version sets M680x0.
1081 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1082 assembler for the same architecture; for example, we know of several
1083 incompatible versions of 680x0 assembly language syntax.
1088 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1089 program in one pass of the source file. This has a subtle impact on the
1090 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1092 @node Object Formats
1093 @section Object File Formats
1095 @cindex object file format
1096 The @sc{gnu} assembler can be configured to produce several alternative
1097 object file formats. For the most part, this does not affect how you
1098 write assembly language programs; but directives for debugging symbols
1099 are typically different in different file formats. @xref{Symbol
1100 Attributes,,Symbol Attributes}.
1103 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1104 @value{OBJ-NAME} format object files.
1106 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1108 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1109 @code{a.out} or COFF format object files.
1112 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1113 @code{b.out} or COFF format object files.
1116 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1117 SOM or ELF format object files.
1122 @section Command Line
1124 @cindex command line conventions
1126 After the program name @command{@value{AS}}, the command line may contain
1127 options and file names. Options may appear in any order, and may be
1128 before, after, or between file names. The order of file names is
1131 @cindex standard input, as input file
1133 @file{--} (two hyphens) by itself names the standard input file
1134 explicitly, as one of the files for @command{@value{AS}} to assemble.
1136 @cindex options, command line
1137 Except for @samp{--} any command line argument that begins with a
1138 hyphen (@samp{-}) is an option. Each option changes the behavior of
1139 @command{@value{AS}}. No option changes the way another option works. An
1140 option is a @samp{-} followed by one or more letters; the case of
1141 the letter is important. All options are optional.
1143 Some options expect exactly one file name to follow them. The file
1144 name may either immediately follow the option's letter (compatible
1145 with older assemblers) or it may be the next command argument (@sc{gnu}
1146 standard). These two command lines are equivalent:
1149 @value{AS} -o my-object-file.o mumble.s
1150 @value{AS} -omy-object-file.o mumble.s
1154 @section Input Files
1157 @cindex source program
1158 @cindex files, input
1159 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1160 describe the program input to one run of @command{@value{AS}}. The program may
1161 be in one or more files; how the source is partitioned into files
1162 doesn't change the meaning of the source.
1164 @c I added "con" prefix to "catenation" just to prove I can overcome my
1165 @c APL training... doc@cygnus.com
1166 The source program is a concatenation of the text in all the files, in the
1169 @c man begin DESCRIPTION
1170 Each time you run @command{@value{AS}} it assembles exactly one source
1171 program. The source program is made up of one or more files.
1172 (The standard input is also a file.)
1174 You give @command{@value{AS}} a command line that has zero or more input file
1175 names. The input files are read (from left file name to right). A
1176 command line argument (in any position) that has no special meaning
1177 is taken to be an input file name.
1179 If you give @command{@value{AS}} no file names it attempts to read one input file
1180 from the @command{@value{AS}} standard input, which is normally your terminal. You
1181 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1184 Use @samp{--} if you need to explicitly name the standard input file
1185 in your command line.
1187 If the source is empty, @command{@value{AS}} produces a small, empty object
1192 @subheading Filenames and Line-numbers
1194 @cindex input file linenumbers
1195 @cindex line numbers, in input files
1196 There are two ways of locating a line in the input file (or files) and
1197 either may be used in reporting error messages. One way refers to a line
1198 number in a physical file; the other refers to a line number in a
1199 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1201 @dfn{Physical files} are those files named in the command line given
1202 to @command{@value{AS}}.
1204 @dfn{Logical files} are simply names declared explicitly by assembler
1205 directives; they bear no relation to physical files. Logical file names help
1206 error messages reflect the original source file, when @command{@value{AS}} source
1207 is itself synthesized from other files. @command{@value{AS}} understands the
1208 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1209 @ref{File,,@code{.file}}.
1212 @section Output (Object) File
1218 Every time you run @command{@value{AS}} it produces an output file, which is
1219 your assembly language program translated into numbers. This file
1220 is the object file. Its default name is
1228 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1230 You can give it another name by using the @option{-o} option. Conventionally,
1231 object file names end with @file{.o}. The default name is used for historical
1232 reasons: older assemblers were capable of assembling self-contained programs
1233 directly into a runnable program. (For some formats, this isn't currently
1234 possible, but it can be done for the @code{a.out} format.)
1238 The object file is meant for input to the linker @code{@value{LD}}. It contains
1239 assembled program code, information to help @code{@value{LD}} integrate
1240 the assembled program into a runnable file, and (optionally) symbolic
1241 information for the debugger.
1243 @c link above to some info file(s) like the description of a.out.
1244 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1247 @section Error and Warning Messages
1249 @c man begin DESCRIPTION
1251 @cindex error messages
1252 @cindex warning messages
1253 @cindex messages from assembler
1254 @command{@value{AS}} may write warnings and error messages to the standard error
1255 file (usually your terminal). This should not happen when a compiler
1256 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1257 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1258 grave problem that stops the assembly.
1262 @cindex format of warning messages
1263 Warning messages have the format
1266 file_name:@b{NNN}:Warning Message Text
1270 @cindex line numbers, in warnings/errors
1271 (where @b{NNN} is a line number). If a logical file name has been given
1272 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1273 the current input file is used. If a logical line number was given
1275 (@pxref{Line,,@code{.line}})
1279 (@pxref{Line,,@code{.line}})
1282 (@pxref{Ln,,@code{.ln}})
1285 then it is used to calculate the number printed,
1286 otherwise the actual line in the current source file is printed. The
1287 message text is intended to be self explanatory (in the grand Unix
1290 @cindex format of error messages
1291 Error messages have the format
1293 file_name:@b{NNN}:FATAL:Error Message Text
1295 The file name and line number are derived as for warning
1296 messages. The actual message text may be rather less explanatory
1297 because many of them aren't supposed to happen.
1300 @chapter Command-Line Options
1302 @cindex options, all versions of assembler
1303 This chapter describes command-line options available in @emph{all}
1304 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1306 to the @value{TARGET}.
1309 to particular machine architectures.
1312 @c man begin DESCRIPTION
1314 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1315 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1316 The assembler arguments must be separated from each other (and the @samp{-Wa})
1317 by commas. For example:
1320 gcc -c -g -O -Wa,-alh,-L file.c
1324 This passes two options to the assembler: @samp{-alh} (emit a listing to
1325 standard output with with high-level and assembly source) and @samp{-L} (retain
1326 local symbols in the symbol table).
1328 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1329 command-line options are automatically passed to the assembler by the compiler.
1330 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1331 precisely what options it passes to each compilation pass, including the
1337 * a:: -a[cdhlns] enable listings
1338 * D:: -D for compatibility
1339 * f:: -f to work faster
1340 * I:: -I for .include search path
1341 @ifclear DIFF-TBL-KLUGE
1342 * K:: -K for compatibility
1344 @ifset DIFF-TBL-KLUGE
1345 * K:: -K for difference tables
1348 * L:: -L to retain local labels
1349 * listing:: --listing-XXX to configure listing output
1350 * M:: -M or --mri to assemble in MRI compatibility mode
1351 * MD:: --MD for dependency tracking
1352 * o:: -o to name the object file
1353 * R:: -R to join data and text sections
1354 * statistics:: --statistics to see statistics about assembly
1355 * traditional-format:: --traditional-format for compatible output
1356 * v:: -v to announce version
1357 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1358 * Z:: -Z to make object file even after errors
1362 @section Enable Listings: @option{-a[cdhlns]}
1371 @cindex listings, enabling
1372 @cindex assembly listings, enabling
1374 These options enable listing output from the assembler. By itself,
1375 @samp{-a} requests high-level, assembly, and symbols listing.
1376 You can use other letters to select specific options for the list:
1377 @samp{-ah} requests a high-level language listing,
1378 @samp{-al} requests an output-program assembly listing, and
1379 @samp{-as} requests a symbol table listing.
1380 High-level listings require that a compiler debugging option like
1381 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1384 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1385 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1386 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1387 omitted from the listing.
1389 Use the @samp{-ad} option to omit debugging directives from the
1392 Once you have specified one of these options, you can further control
1393 listing output and its appearance using the directives @code{.list},
1394 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1396 The @samp{-an} option turns off all forms processing.
1397 If you do not request listing output with one of the @samp{-a} options, the
1398 listing-control directives have no effect.
1400 The letters after @samp{-a} may be combined into one option,
1401 @emph{e.g.}, @samp{-aln}.
1403 Note if the assembler source is coming from the standard input (eg because it
1404 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1405 is being used) then the listing will not contain any comments or preprocessor
1406 directives. This is because the listing code buffers input source lines from
1407 stdin only after they have been preprocessed by the assembler. This reduces
1408 memory usage and makes the code more efficient.
1411 @section @option{-D}
1414 This option has no effect whatsoever, but it is accepted to make it more
1415 likely that scripts written for other assemblers also work with
1416 @command{@value{AS}}.
1419 @section Work Faster: @option{-f}
1422 @cindex trusted compiler
1423 @cindex faster processing (@option{-f})
1424 @samp{-f} should only be used when assembling programs written by a
1425 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1426 and comment preprocessing on
1427 the input file(s) before assembling them. @xref{Preprocessing,
1431 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1432 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1437 @section @code{.include} search path: @option{-I} @var{path}
1439 @kindex -I @var{path}
1440 @cindex paths for @code{.include}
1441 @cindex search path for @code{.include}
1442 @cindex @code{include} directive search path
1443 Use this option to add a @var{path} to the list of directories
1444 @command{@value{AS}} searches for files specified in @code{.include}
1445 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1446 many times as necessary to include a variety of paths. The current
1447 working directory is always searched first; after that, @command{@value{AS}}
1448 searches any @samp{-I} directories in the same order as they were
1449 specified (left to right) on the command line.
1452 @section Difference Tables: @option{-K}
1455 @ifclear DIFF-TBL-KLUGE
1456 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1457 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1458 where it can be used to warn when the assembler alters the machine code
1459 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1460 family does not have the addressing limitations that sometimes lead to this
1461 alteration on other platforms.
1464 @ifset DIFF-TBL-KLUGE
1465 @cindex difference tables, warning
1466 @cindex warning for altered difference tables
1467 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1468 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1469 You can use the @samp{-K} option if you want a warning issued when this
1474 @section Include Local Labels: @option{-L}
1477 @cindex local labels, retaining in output
1478 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1479 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1480 debugging, because they are intended for the use of programs (like
1481 compilers) that compose assembler programs, not for your notice.
1482 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1483 normally debug with them.
1485 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1486 in the object file. Usually if you do this you also tell the linker
1487 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1489 By default, a local label is any label beginning with @samp{L}, but each
1490 target is allowed to redefine the local label prefix.
1492 On the HPPA local labels begin with @samp{L$}.
1496 @section Configuring listing output: @option{--listing}
1498 The listing feature of the assembler can be enabled via the command line switch
1499 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1500 hex dump of the corresponding locations in the output object file, and displays
1501 them as a listing file. The format of this listing can be controlled by pseudo
1502 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1503 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1506 @item --listing-lhs-width=@samp{number}
1507 @kindex --listing-lhs-width
1508 @cindex Width of first line disassembly output
1509 Sets the maximum width, in words, of the first line of the hex byte dump. This
1510 dump appears on the left hand side of the listing output.
1512 @item --listing-lhs-width2=@samp{number}
1513 @kindex --listing-lhs-width2
1514 @cindex Width of continuation lines of disassembly output
1515 Sets the maximum width, in words, of any further lines of the hex byte dump for
1516 a given inut source line. If this value is not specified, it defaults to being
1517 the same as the value specified for @samp{--listing-lhs-width}. If neither
1518 switch is used the default is to one.
1520 @item --listing-rhs-width=@samp{number}
1521 @kindex --listing-rhs-width
1522 @cindex Width of source line output
1523 Sets the maximum width, in characters, of the source line that is displayed
1524 alongside the hex dump. The default value for this parameter is 100. The
1525 source line is displayed on the right hand side of the listing output.
1527 @item --listing-cont-lines=@samp{number}
1528 @kindex --listing-cont-lines
1529 @cindex Maximum number of continuation lines
1530 Sets the maximum number of continuation lines of hex dump that will be
1531 displayed for a given single line of source input. The default value is 4.
1535 @section Assemble in MRI Compatibility Mode: @option{-M}
1538 @cindex MRI compatibility mode
1539 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1540 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1541 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1542 configured target) assembler from Microtec Research. The exact nature of the
1543 MRI syntax will not be documented here; see the MRI manuals for more
1544 information. Note in particular that the handling of macros and macro
1545 arguments is somewhat different. The purpose of this option is to permit
1546 assembling existing MRI assembler code using @command{@value{AS}}.
1548 The MRI compatibility is not complete. Certain operations of the MRI assembler
1549 depend upon its object file format, and can not be supported using other object
1550 file formats. Supporting these would require enhancing each object file format
1551 individually. These are:
1554 @item global symbols in common section
1556 The m68k MRI assembler supports common sections which are merged by the linker.
1557 Other object file formats do not support this. @command{@value{AS}} handles
1558 common sections by treating them as a single common symbol. It permits local
1559 symbols to be defined within a common section, but it can not support global
1560 symbols, since it has no way to describe them.
1562 @item complex relocations
1564 The MRI assemblers support relocations against a negated section address, and
1565 relocations which combine the start addresses of two or more sections. These
1566 are not support by other object file formats.
1568 @item @code{END} pseudo-op specifying start address
1570 The MRI @code{END} pseudo-op permits the specification of a start address.
1571 This is not supported by other object file formats. The start address may
1572 instead be specified using the @option{-e} option to the linker, or in a linker
1575 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1577 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1578 name to the output file. This is not supported by other object file formats.
1580 @item @code{ORG} pseudo-op
1582 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1583 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1584 which changes the location within the current section. Absolute sections are
1585 not supported by other object file formats. The address of a section may be
1586 assigned within a linker script.
1589 There are some other features of the MRI assembler which are not supported by
1590 @command{@value{AS}}, typically either because they are difficult or because they
1591 seem of little consequence. Some of these may be supported in future releases.
1595 @item EBCDIC strings
1597 EBCDIC strings are not supported.
1599 @item packed binary coded decimal
1601 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1602 and @code{DCB.P} pseudo-ops are not supported.
1604 @item @code{FEQU} pseudo-op
1606 The m68k @code{FEQU} pseudo-op is not supported.
1608 @item @code{NOOBJ} pseudo-op
1610 The m68k @code{NOOBJ} pseudo-op is not supported.
1612 @item @code{OPT} branch control options
1614 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1615 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1616 relaxes all branches, whether forward or backward, to an appropriate size, so
1617 these options serve no purpose.
1619 @item @code{OPT} list control options
1621 The following m68k @code{OPT} list control options are ignored: @code{C},
1622 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1623 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1625 @item other @code{OPT} options
1627 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1628 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1630 @item @code{OPT} @code{D} option is default
1632 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1633 @code{OPT NOD} may be used to turn it off.
1635 @item @code{XREF} pseudo-op.
1637 The m68k @code{XREF} pseudo-op is ignored.
1639 @item @code{.debug} pseudo-op
1641 The i960 @code{.debug} pseudo-op is not supported.
1643 @item @code{.extended} pseudo-op
1645 The i960 @code{.extended} pseudo-op is not supported.
1647 @item @code{.list} pseudo-op.
1649 The various options of the i960 @code{.list} pseudo-op are not supported.
1651 @item @code{.optimize} pseudo-op
1653 The i960 @code{.optimize} pseudo-op is not supported.
1655 @item @code{.output} pseudo-op
1657 The i960 @code{.output} pseudo-op is not supported.
1659 @item @code{.setreal} pseudo-op
1661 The i960 @code{.setreal} pseudo-op is not supported.
1666 @section Dependency tracking: @option{--MD}
1669 @cindex dependency tracking
1672 @command{@value{AS}} can generate a dependency file for the file it creates. This
1673 file consists of a single rule suitable for @code{make} describing the
1674 dependencies of the main source file.
1676 The rule is written to the file named in its argument.
1678 This feature is used in the automatic updating of makefiles.
1681 @section Name the Object File: @option{-o}
1684 @cindex naming object file
1685 @cindex object file name
1686 There is always one object file output when you run @command{@value{AS}}. By
1687 default it has the name
1690 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1704 You use this option (which takes exactly one filename) to give the
1705 object file a different name.
1707 Whatever the object file is called, @command{@value{AS}} overwrites any
1708 existing file of the same name.
1711 @section Join Data and Text Sections: @option{-R}
1714 @cindex data and text sections, joining
1715 @cindex text and data sections, joining
1716 @cindex joining text and data sections
1717 @cindex merging text and data sections
1718 @option{-R} tells @command{@value{AS}} to write the object file as if all
1719 data-section data lives in the text section. This is only done at
1720 the very last moment: your binary data are the same, but data
1721 section parts are relocated differently. The data section part of
1722 your object file is zero bytes long because all its bytes are
1723 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1725 When you specify @option{-R} it would be possible to generate shorter
1726 address displacements (because we do not have to cross between text and
1727 data section). We refrain from doing this simply for compatibility with
1728 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1731 When @command{@value{AS}} is configured for COFF output,
1732 this option is only useful if you use sections named @samp{.text} and
1737 @option{-R} is not supported for any of the HPPA targets. Using
1738 @option{-R} generates a warning from @command{@value{AS}}.
1742 @section Display Assembly Statistics: @option{--statistics}
1744 @kindex --statistics
1745 @cindex statistics, about assembly
1746 @cindex time, total for assembly
1747 @cindex space used, maximum for assembly
1748 Use @samp{--statistics} to display two statistics about the resources used by
1749 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1750 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1753 @node traditional-format
1754 @section Compatible output: @option{--traditional-format}
1756 @kindex --traditional-format
1757 For some targets, the output of @command{@value{AS}} is different in some ways
1758 from the output of some existing assembler. This switch requests
1759 @command{@value{AS}} to use the traditional format instead.
1761 For example, it disables the exception frame optimizations which
1762 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1765 @section Announce Version: @option{-v}
1769 @cindex assembler version
1770 @cindex version of assembler
1771 You can find out what version of as is running by including the
1772 option @samp{-v} (which you can also spell as @samp{-version}) on the
1776 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1778 @command{@value{AS}} should never give a warning or error message when
1779 assembling compiler output. But programs written by people often
1780 cause @command{@value{AS}} to give a warning that a particular assumption was
1781 made. All such warnings are directed to the standard error file.
1784 @kindex @samp{--no-warn}
1785 @cindex suppressing warnings
1786 @cindex warnings, suppressing
1787 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1788 This only affects the warning messages: it does not change any particular of
1789 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1792 @kindex @samp{--fatal-warnings}
1793 @cindex errors, caused by warnings
1794 @cindex warnings, causing error
1795 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1796 files that generate warnings to be in error.
1798 @kindex @samp{--warn}
1799 @cindex warnings, switching on
1800 You can switch these options off again by specifying @option{--warn}, which
1801 causes warnings to be output as usual.
1804 @section Generate Object File in Spite of Errors: @option{-Z}
1805 @cindex object file, after errors
1806 @cindex errors, continuing after
1807 After an error message, @command{@value{AS}} normally produces no output. If for
1808 some reason you are interested in object file output even after
1809 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1810 option. If there are any errors, @command{@value{AS}} continues anyways, and
1811 writes an object file after a final warning message of the form @samp{@var{n}
1812 errors, @var{m} warnings, generating bad object file.}
1817 @cindex machine-independent syntax
1818 @cindex syntax, machine-independent
1819 This chapter describes the machine-independent syntax allowed in a
1820 source file. @command{@value{AS}} syntax is similar to what many other
1821 assemblers use; it is inspired by the BSD 4.2
1826 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1830 * Preprocessing:: Preprocessing
1831 * Whitespace:: Whitespace
1832 * Comments:: Comments
1833 * Symbol Intro:: Symbols
1834 * Statements:: Statements
1835 * Constants:: Constants
1839 @section Preprocessing
1841 @cindex preprocessing
1842 The @command{@value{AS}} internal preprocessor:
1844 @cindex whitespace, removed by preprocessor
1846 adjusts and removes extra whitespace. It leaves one space or tab before
1847 the keywords on a line, and turns any other whitespace on the line into
1850 @cindex comments, removed by preprocessor
1852 removes all comments, replacing them with a single space, or an
1853 appropriate number of newlines.
1855 @cindex constants, converted by preprocessor
1857 converts character constants into the appropriate numeric values.
1860 It does not do macro processing, include file handling, or
1861 anything else you may get from your C compiler's preprocessor. You can
1862 do include file processing with the @code{.include} directive
1863 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1864 to get other ``CPP'' style preprocessing, by giving the input file a
1865 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1866 Output, gcc.info, Using GNU CC}.
1868 Excess whitespace, comments, and character constants
1869 cannot be used in the portions of the input text that are not
1872 @cindex turning preprocessing on and off
1873 @cindex preprocessing, turning on and off
1876 If the first line of an input file is @code{#NO_APP} or if you use the
1877 @samp{-f} option, whitespace and comments are not removed from the input file.
1878 Within an input file, you can ask for whitespace and comment removal in
1879 specific portions of the by putting a line that says @code{#APP} before the
1880 text that may contain whitespace or comments, and putting a line that says
1881 @code{#NO_APP} after this text. This feature is mainly intend to support
1882 @code{asm} statements in compilers whose output is otherwise free of comments
1889 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1890 Whitespace is used to separate symbols, and to make programs neater for
1891 people to read. Unless within character constants
1892 (@pxref{Characters,,Character Constants}), any whitespace means the same
1893 as exactly one space.
1899 There are two ways of rendering comments to @command{@value{AS}}. In both
1900 cases the comment is equivalent to one space.
1902 Anything from @samp{/*} through the next @samp{*/} is a comment.
1903 This means you may not nest these comments.
1907 The only way to include a newline ('\n') in a comment
1908 is to use this sort of comment.
1911 /* This sort of comment does not nest. */
1914 @cindex line comment character
1915 Anything from the @dfn{line comment} character to the next newline
1916 is considered a comment and is ignored. The line comment character is
1918 @samp{;} for the AMD 29K family;
1921 @samp{;} on the ARC;
1924 @samp{@@} on the ARM;
1927 @samp{;} for the H8/300 family;
1930 @samp{!} for the H8/500 family;
1933 @samp{;} for the HPPA;
1936 @samp{#} on the i386 and x86-64;
1939 @samp{#} on the i960;
1942 @samp{;} for the PDP-11;
1945 @samp{;} for picoJava;
1948 @samp{;} for Motorola PowerPC;
1951 @samp{!} for the Hitachi SH;
1954 @samp{!} on the SPARC;
1957 @samp{#} on the m32r;
1960 @samp{|} on the 680x0;
1963 @samp{#} on the 68HC11 and 68HC12;
1966 @samp{;} on the M880x0;
1969 @samp{#} on the Vax;
1972 @samp{!} for the Z8000;
1975 @samp{#} on the V850;
1977 see @ref{Machine Dependencies}. @refill
1978 @c FIXME What about i860?
1981 On some machines there are two different line comment characters. One
1982 character only begins a comment if it is the first non-whitespace character on
1983 a line, while the other always begins a comment.
1987 The V850 assembler also supports a double dash as starting a comment that
1988 extends to the end of the line.
1994 @cindex lines starting with @code{#}
1995 @cindex logical line numbers
1996 To be compatible with past assemblers, lines that begin with @samp{#} have a
1997 special interpretation. Following the @samp{#} should be an absolute
1998 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1999 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2000 new logical file name. The rest of the line, if any, should be whitespace.
2002 If the first non-whitespace characters on the line are not numeric,
2003 the line is ignored. (Just like a comment.)
2006 # This is an ordinary comment.
2007 # 42-6 "new_file_name" # New logical file name
2008 # This is logical line # 36.
2010 This feature is deprecated, and may disappear from future versions
2011 of @command{@value{AS}}.
2016 @cindex characters used in symbols
2017 @ifclear SPECIAL-SYMS
2018 A @dfn{symbol} is one or more characters chosen from the set of all
2019 letters (both upper and lower case), digits and the three characters
2025 A @dfn{symbol} is one or more characters chosen from the set of all
2026 letters (both upper and lower case), digits and the three characters
2027 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2033 On most machines, you can also use @code{$} in symbol names; exceptions
2034 are noted in @ref{Machine Dependencies}.
2036 No symbol may begin with a digit. Case is significant.
2037 There is no length limit: all characters are significant. Symbols are
2038 delimited by characters not in that set, or by the beginning of a file
2039 (since the source program must end with a newline, the end of a file is
2040 not a possible symbol delimiter). @xref{Symbols}.
2041 @cindex length of symbols
2046 @cindex statements, structure of
2047 @cindex line separator character
2048 @cindex statement separator character
2050 @ifclear abnormal-separator
2051 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2052 semicolon (@samp{;}). The newline or semicolon is considered part of
2053 the preceding statement. Newlines and semicolons within character
2054 constants are an exception: they do not end statements.
2056 @ifset abnormal-separator
2058 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2059 sign (@samp{@@}). The newline or at sign is considered part of the
2060 preceding statement. Newlines and at signs within character constants
2061 are an exception: they do not end statements.
2064 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2065 point (@samp{!}). The newline or exclamation point is considered part of the
2066 preceding statement. Newlines and exclamation points within character
2067 constants are an exception: they do not end statements.
2070 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2071 H8/300) a dollar sign (@samp{$}); or (for the
2074 (@samp{;}). The newline or separator character is considered part of
2075 the preceding statement. Newlines and separators within character
2076 constants are an exception: they do not end statements.
2081 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2082 separator character. (The line separator is usually @samp{;}, unless
2083 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2084 newline or separator character is considered part of the preceding
2085 statement. Newlines and separators within character constants are an
2086 exception: they do not end statements.
2089 @cindex newline, required at file end
2090 @cindex EOF, newline must precede
2091 It is an error to end any statement with end-of-file: the last
2092 character of any input file should be a newline.@refill
2094 An empty statement is allowed, and may include whitespace. It is ignored.
2096 @cindex instructions and directives
2097 @cindex directives and instructions
2098 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2099 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2101 A statement begins with zero or more labels, optionally followed by a
2102 key symbol which determines what kind of statement it is. The key
2103 symbol determines the syntax of the rest of the statement. If the
2104 symbol begins with a dot @samp{.} then the statement is an assembler
2105 directive: typically valid for any computer. If the symbol begins with
2106 a letter the statement is an assembly language @dfn{instruction}: it
2107 assembles into a machine language instruction.
2109 Different versions of @command{@value{AS}} for different computers
2110 recognize different instructions. In fact, the same symbol may
2111 represent a different instruction in a different computer's assembly
2115 @cindex @code{:} (label)
2116 @cindex label (@code{:})
2117 A label is a symbol immediately followed by a colon (@code{:}).
2118 Whitespace before a label or after a colon is permitted, but you may not
2119 have whitespace between a label's symbol and its colon. @xref{Labels}.
2122 For HPPA targets, labels need not be immediately followed by a colon, but
2123 the definition of a label must begin in column zero. This also implies that
2124 only one label may be defined on each line.
2128 label: .directive followed by something
2129 another_label: # This is an empty statement.
2130 instruction operand_1, operand_2, @dots{}
2137 A constant is a number, written so that its value is known by
2138 inspection, without knowing any context. Like this:
2141 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2142 .ascii "Ring the bell\7" # A string constant.
2143 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2144 .float 0f-314159265358979323846264338327\
2145 95028841971.693993751E-40 # - pi, a flonum.
2150 * Characters:: Character Constants
2151 * Numbers:: Number Constants
2155 @subsection Character Constants
2157 @cindex character constants
2158 @cindex constants, character
2159 There are two kinds of character constants. A @dfn{character} stands
2160 for one character in one byte and its value may be used in
2161 numeric expressions. String constants (properly called string
2162 @emph{literals}) are potentially many bytes and their values may not be
2163 used in arithmetic expressions.
2167 * Chars:: Characters
2171 @subsubsection Strings
2173 @cindex string constants
2174 @cindex constants, string
2175 A @dfn{string} is written between double-quotes. It may contain
2176 double-quotes or null characters. The way to get special characters
2177 into a string is to @dfn{escape} these characters: precede them with
2178 a backslash @samp{\} character. For example @samp{\\} represents
2179 one backslash: the first @code{\} is an escape which tells
2180 @command{@value{AS}} to interpret the second character literally as a backslash
2181 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2182 escape character). The complete list of escapes follows.
2184 @cindex escape codes, character
2185 @cindex character escape codes
2188 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2190 @cindex @code{\b} (backspace character)
2191 @cindex backspace (@code{\b})
2193 Mnemonic for backspace; for ASCII this is octal code 010.
2196 @c Mnemonic for EOText; for ASCII this is octal code 004.
2198 @cindex @code{\f} (formfeed character)
2199 @cindex formfeed (@code{\f})
2201 Mnemonic for FormFeed; for ASCII this is octal code 014.
2203 @cindex @code{\n} (newline character)
2204 @cindex newline (@code{\n})
2206 Mnemonic for newline; for ASCII this is octal code 012.
2209 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2211 @cindex @code{\r} (carriage return character)
2212 @cindex carriage return (@code{\r})
2214 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2217 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2218 @c other assemblers.
2220 @cindex @code{\t} (tab)
2221 @cindex tab (@code{\t})
2223 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2226 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2227 @c @item \x @var{digit} @var{digit} @var{digit}
2228 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2230 @cindex @code{\@var{ddd}} (octal character code)
2231 @cindex octal character code (@code{\@var{ddd}})
2232 @item \ @var{digit} @var{digit} @var{digit}
2233 An octal character code. The numeric code is 3 octal digits.
2234 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2235 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2237 @cindex @code{\@var{xd...}} (hex character code)
2238 @cindex hex character code (@code{\@var{xd...}})
2239 @item \@code{x} @var{hex-digits...}
2240 A hex character code. All trailing hex digits are combined. Either upper or
2241 lower case @code{x} works.
2243 @cindex @code{\\} (@samp{\} character)
2244 @cindex backslash (@code{\\})
2246 Represents one @samp{\} character.
2249 @c Represents one @samp{'} (accent acute) character.
2250 @c This is needed in single character literals
2251 @c (@xref{Characters,,Character Constants}.) to represent
2254 @cindex @code{\"} (doublequote character)
2255 @cindex doublequote (@code{\"})
2257 Represents one @samp{"} character. Needed in strings to represent
2258 this character, because an unescaped @samp{"} would end the string.
2260 @item \ @var{anything-else}
2261 Any other character when escaped by @kbd{\} gives a warning, but
2262 assembles as if the @samp{\} was not present. The idea is that if
2263 you used an escape sequence you clearly didn't want the literal
2264 interpretation of the following character. However @command{@value{AS}} has no
2265 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2266 code and warns you of the fact.
2269 Which characters are escapable, and what those escapes represent,
2270 varies widely among assemblers. The current set is what we think
2271 the BSD 4.2 assembler recognizes, and is a subset of what most C
2272 compilers recognize. If you are in doubt, do not use an escape
2276 @subsubsection Characters
2278 @cindex single character constant
2279 @cindex character, single
2280 @cindex constant, single character
2281 A single character may be written as a single quote immediately
2282 followed by that character. The same escapes apply to characters as
2283 to strings. So if you want to write the character backslash, you
2284 must write @kbd{'\\} where the first @code{\} escapes the second
2285 @code{\}. As you can see, the quote is an acute accent, not a
2286 grave accent. A newline
2288 @ifclear abnormal-separator
2289 (or semicolon @samp{;})
2291 @ifset abnormal-separator
2293 (or at sign @samp{@@})
2296 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2302 immediately following an acute accent is taken as a literal character
2303 and does not count as the end of a statement. The value of a character
2304 constant in a numeric expression is the machine's byte-wide code for
2305 that character. @command{@value{AS}} assumes your character code is ASCII:
2306 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2309 @subsection Number Constants
2311 @cindex constants, number
2312 @cindex number constants
2313 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2314 are stored in the target machine. @emph{Integers} are numbers that
2315 would fit into an @code{int} in the C language. @emph{Bignums} are
2316 integers, but they are stored in more than 32 bits. @emph{Flonums}
2317 are floating point numbers, described below.
2320 * Integers:: Integers
2325 * Bit Fields:: Bit Fields
2331 @subsubsection Integers
2333 @cindex constants, integer
2335 @cindex binary integers
2336 @cindex integers, binary
2337 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2338 the binary digits @samp{01}.
2340 @cindex octal integers
2341 @cindex integers, octal
2342 An octal integer is @samp{0} followed by zero or more of the octal
2343 digits (@samp{01234567}).
2345 @cindex decimal integers
2346 @cindex integers, decimal
2347 A decimal integer starts with a non-zero digit followed by zero or
2348 more digits (@samp{0123456789}).
2350 @cindex hexadecimal integers
2351 @cindex integers, hexadecimal
2352 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2353 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2355 Integers have the usual values. To denote a negative integer, use
2356 the prefix operator @samp{-} discussed under expressions
2357 (@pxref{Prefix Ops,,Prefix Operators}).
2360 @subsubsection Bignums
2363 @cindex constants, bignum
2364 A @dfn{bignum} has the same syntax and semantics as an integer
2365 except that the number (or its negative) takes more than 32 bits to
2366 represent in binary. The distinction is made because in some places
2367 integers are permitted while bignums are not.
2370 @subsubsection Flonums
2372 @cindex floating point numbers
2373 @cindex constants, floating point
2375 @cindex precision, floating point
2376 A @dfn{flonum} represents a floating point number. The translation is
2377 indirect: a decimal floating point number from the text is converted by
2378 @command{@value{AS}} to a generic binary floating point number of more than
2379 sufficient precision. This generic floating point number is converted
2380 to a particular computer's floating point format (or formats) by a
2381 portion of @command{@value{AS}} specialized to that computer.
2383 A flonum is written by writing (in order)
2388 (@samp{0} is optional on the HPPA.)
2392 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2394 @kbd{e} is recommended. Case is not important.
2396 @c FIXME: verify if flonum syntax really this vague for most cases
2397 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2398 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2401 On the H8/300, H8/500,
2403 and AMD 29K architectures, the letter must be
2404 one of the letters @samp{DFPRSX} (in upper or lower case).
2406 On the ARC, the letter must be one of the letters @samp{DFRS}
2407 (in upper or lower case).
2409 On the Intel 960 architecture, the letter must be
2410 one of the letters @samp{DFT} (in upper or lower case).
2412 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2416 One of the letters @samp{DFPRSX} (in upper or lower case).
2419 One of the letters @samp{DFRS} (in upper or lower case).
2422 One of the letters @samp{DFPRSX} (in upper or lower case).
2425 The letter @samp{E} (upper case only).
2428 One of the letters @samp{DFT} (in upper or lower case).
2433 An optional sign: either @samp{+} or @samp{-}.
2436 An optional @dfn{integer part}: zero or more decimal digits.
2439 An optional @dfn{fractional part}: @samp{.} followed by zero
2440 or more decimal digits.
2443 An optional exponent, consisting of:
2447 An @samp{E} or @samp{e}.
2448 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2449 @c principle this can perfectly well be different on different targets.
2451 Optional sign: either @samp{+} or @samp{-}.
2453 One or more decimal digits.
2458 At least one of the integer part or the fractional part must be
2459 present. The floating point number has the usual base-10 value.
2461 @command{@value{AS}} does all processing using integers. Flonums are computed
2462 independently of any floating point hardware in the computer running
2463 @command{@value{AS}}.
2467 @c Bit fields are written as a general facility but are also controlled
2468 @c by a conditional-compilation flag---which is as of now (21mar91)
2469 @c turned on only by the i960 config of GAS.
2471 @subsubsection Bit Fields
2474 @cindex constants, bit field
2475 You can also define numeric constants as @dfn{bit fields}.
2476 specify two numbers separated by a colon---
2478 @var{mask}:@var{value}
2481 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2484 The resulting number is then packed
2486 @c this conditional paren in case bit fields turned on elsewhere than 960
2487 (in host-dependent byte order)
2489 into a field whose width depends on which assembler directive has the
2490 bit-field as its argument. Overflow (a result from the bitwise and
2491 requiring more binary digits to represent) is not an error; instead,
2492 more constants are generated, of the specified width, beginning with the
2493 least significant digits.@refill
2495 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2496 @code{.short}, and @code{.word} accept bit-field arguments.
2501 @chapter Sections and Relocation
2506 * Secs Background:: Background
2507 * Ld Sections:: Linker Sections
2508 * As Sections:: Assembler Internal Sections
2509 * Sub-Sections:: Sub-Sections
2513 @node Secs Background
2516 Roughly, a section is a range of addresses, with no gaps; all data
2517 ``in'' those addresses is treated the same for some particular purpose.
2518 For example there may be a ``read only'' section.
2520 @cindex linker, and assembler
2521 @cindex assembler, and linker
2522 The linker @code{@value{LD}} reads many object files (partial programs) and
2523 combines their contents to form a runnable program. When @command{@value{AS}}
2524 emits an object file, the partial program is assumed to start at address 0.
2525 @code{@value{LD}} assigns the final addresses for the partial program, so that
2526 different partial programs do not overlap. This is actually an
2527 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2530 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2531 addresses. These blocks slide to their run-time addresses as rigid
2532 units; their length does not change and neither does the order of bytes
2533 within them. Such a rigid unit is called a @emph{section}. Assigning
2534 run-time addresses to sections is called @dfn{relocation}. It includes
2535 the task of adjusting mentions of object-file addresses so they refer to
2536 the proper run-time addresses.
2538 For the H8/300 and H8/500,
2539 and for the Hitachi SH,
2540 @command{@value{AS}} pads sections if needed to
2541 ensure they end on a word (sixteen bit) boundary.
2544 @cindex standard assembler sections
2545 An object file written by @command{@value{AS}} has at least three sections, any
2546 of which may be empty. These are named @dfn{text}, @dfn{data} and
2551 When it generates COFF output,
2553 @command{@value{AS}} can also generate whatever other named sections you specify
2554 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2555 If you do not use any directives that place output in the @samp{.text}
2556 or @samp{.data} sections, these sections still exist, but are empty.
2561 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2563 @command{@value{AS}} can also generate whatever other named sections you
2564 specify using the @samp{.space} and @samp{.subspace} directives. See
2565 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2566 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2567 assembler directives.
2570 Additionally, @command{@value{AS}} uses different names for the standard
2571 text, data, and bss sections when generating SOM output. Program text
2572 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2573 BSS into @samp{$BSS$}.
2577 Within the object file, the text section starts at address @code{0}, the
2578 data section follows, and the bss section follows the data section.
2581 When generating either SOM or ELF output files on the HPPA, the text
2582 section starts at address @code{0}, the data section at address
2583 @code{0x4000000}, and the bss section follows the data section.
2586 To let @code{@value{LD}} know which data changes when the sections are
2587 relocated, and how to change that data, @command{@value{AS}} also writes to the
2588 object file details of the relocation needed. To perform relocation
2589 @code{@value{LD}} must know, each time an address in the object
2593 Where in the object file is the beginning of this reference to
2596 How long (in bytes) is this reference?
2598 Which section does the address refer to? What is the numeric value of
2600 (@var{address}) @minus{} (@var{start-address of section})?
2603 Is the reference to an address ``Program-Counter relative''?
2606 @cindex addresses, format of
2607 @cindex section-relative addressing
2608 In fact, every address @command{@value{AS}} ever uses is expressed as
2610 (@var{section}) + (@var{offset into section})
2613 Further, most expressions @command{@value{AS}} computes have this section-relative
2616 (For some object formats, such as SOM for the HPPA, some expressions are
2617 symbol-relative instead.)
2620 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2621 @var{N} into section @var{secname}.''
2623 Apart from text, data and bss sections you need to know about the
2624 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2625 addresses in the absolute section remain unchanged. For example, address
2626 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2627 @code{@value{LD}}. Although the linker never arranges two partial programs'
2628 data sections with overlapping addresses after linking, @emph{by definition}
2629 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2630 part of a program is always the same address when the program is running as
2631 address @code{@{absolute@ 239@}} in any other part of the program.
2633 The idea of sections is extended to the @dfn{undefined} section. Any
2634 address whose section is unknown at assembly time is by definition
2635 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2636 Since numbers are always defined, the only way to generate an undefined
2637 address is to mention an undefined symbol. A reference to a named
2638 common block would be such a symbol: its value is unknown at assembly
2639 time so it has section @emph{undefined}.
2641 By analogy the word @emph{section} is used to describe groups of sections in
2642 the linked program. @code{@value{LD}} puts all partial programs' text
2643 sections in contiguous addresses in the linked program. It is
2644 customary to refer to the @emph{text section} of a program, meaning all
2645 the addresses of all partial programs' text sections. Likewise for
2646 data and bss sections.
2648 Some sections are manipulated by @code{@value{LD}}; others are invented for
2649 use of @command{@value{AS}} and have no meaning except during assembly.
2652 @section Linker Sections
2653 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2658 @cindex named sections
2659 @cindex sections, named
2660 @item named sections
2663 @cindex text section
2664 @cindex data section
2668 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2669 separate but equal sections. Anything you can say of one section is
2672 When the program is running, however, it is
2673 customary for the text section to be unalterable. The
2674 text section is often shared among processes: it contains
2675 instructions, constants and the like. The data section of a running
2676 program is usually alterable: for example, C variables would be stored
2677 in the data section.
2682 This section contains zeroed bytes when your program begins running. It
2683 is used to hold uninitialized variables or common storage. The length of
2684 each partial program's bss section is important, but because it starts
2685 out containing zeroed bytes there is no need to store explicit zero
2686 bytes in the object file. The bss section was invented to eliminate
2687 those explicit zeros from object files.
2689 @cindex absolute section
2690 @item absolute section
2691 Address 0 of this section is always ``relocated'' to runtime address 0.
2692 This is useful if you want to refer to an address that @code{@value{LD}} must
2693 not change when relocating. In this sense we speak of absolute
2694 addresses being ``unrelocatable'': they do not change during relocation.
2696 @cindex undefined section
2697 @item undefined section
2698 This ``section'' is a catch-all for address references to objects not in
2699 the preceding sections.
2700 @c FIXME: ref to some other doc on obj-file formats could go here.
2703 @cindex relocation example
2704 An idealized example of three relocatable sections follows.
2706 The example uses the traditional section names @samp{.text} and @samp{.data}.
2708 Memory addresses are on the horizontal axis.
2712 @c END TEXI2ROFF-KILL
2715 partial program # 1: |ttttt|dddd|00|
2722 partial program # 2: |TTT|DDD|000|
2725 +--+---+-----+--+----+---+-----+~~
2726 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2727 +--+---+-----+--+----+---+-----+~~
2729 addresses: 0 @dots{}
2736 \line{\it Partial program \#1: \hfil}
2737 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2738 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2740 \line{\it Partial program \#2: \hfil}
2741 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2742 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2744 \line{\it linked program: \hfil}
2745 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2746 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2747 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2748 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2750 \line{\it addresses: \hfil}
2754 @c END TEXI2ROFF-KILL
2757 @section Assembler Internal Sections
2759 @cindex internal assembler sections
2760 @cindex sections in messages, internal
2761 These sections are meant only for the internal use of @command{@value{AS}}. They
2762 have no meaning at run-time. You do not really need to know about these
2763 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2764 warning messages, so it might be helpful to have an idea of their
2765 meanings to @command{@value{AS}}. These sections are used to permit the
2766 value of every expression in your assembly language program to be a
2767 section-relative address.
2770 @cindex assembler internal logic error
2771 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2772 An internal assembler logic error has been found. This means there is a
2773 bug in the assembler.
2775 @cindex expr (internal section)
2777 The assembler stores complex expression internally as combinations of
2778 symbols. When it needs to represent an expression as a symbol, it puts
2779 it in the expr section.
2781 @c FIXME item transfer[t] vector preload
2782 @c FIXME item transfer[t] vector postload
2783 @c FIXME item register
2787 @section Sub-Sections
2789 @cindex numbered subsections
2790 @cindex grouping data
2796 fall into two sections: text and data.
2798 You may have separate groups of
2800 data in named sections
2804 data in named sections
2810 that you want to end up near to each other in the object file, even though they
2811 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2812 use @dfn{subsections} for this purpose. Within each section, there can be
2813 numbered subsections with values from 0 to 8192. Objects assembled into the
2814 same subsection go into the object file together with other objects in the same
2815 subsection. For example, a compiler might want to store constants in the text
2816 section, but might not want to have them interspersed with the program being
2817 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2818 section of code being output, and a @samp{.text 1} before each group of
2819 constants being output.
2821 Subsections are optional. If you do not use subsections, everything
2822 goes in subsection number zero.
2825 Each subsection is zero-padded up to a multiple of four bytes.
2826 (Subsections may be padded a different amount on different flavors
2827 of @command{@value{AS}}.)
2831 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2832 boundary (two bytes).
2833 The same is true on the Hitachi SH.
2836 @c FIXME section padding (alignment)?
2837 @c Rich Pixley says padding here depends on target obj code format; that
2838 @c doesn't seem particularly useful to say without further elaboration,
2839 @c so for now I say nothing about it. If this is a generic BFD issue,
2840 @c these paragraphs might need to vanish from this manual, and be
2841 @c discussed in BFD chapter of binutils (or some such).
2844 On the AMD 29K family, no particular padding is added to section or
2845 subsection sizes; @value{AS} forces no alignment on this platform.
2849 Subsections appear in your object file in numeric order, lowest numbered
2850 to highest. (All this to be compatible with other people's assemblers.)
2851 The object file contains no representation of subsections; @code{@value{LD}} and
2852 other programs that manipulate object files see no trace of them.
2853 They just see all your text subsections as a text section, and all your
2854 data subsections as a data section.
2856 To specify which subsection you want subsequent statements assembled
2857 into, use a numeric argument to specify it, in a @samp{.text
2858 @var{expression}} or a @samp{.data @var{expression}} statement.
2861 When generating COFF output, you
2866 can also use an extra subsection
2867 argument with arbitrary named sections: @samp{.section @var{name},
2870 @var{Expression} should be an absolute expression.
2871 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2872 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2873 begins in @code{text 0}. For instance:
2875 .text 0 # The default subsection is text 0 anyway.
2876 .ascii "This lives in the first text subsection. *"
2878 .ascii "But this lives in the second text subsection."
2880 .ascii "This lives in the data section,"
2881 .ascii "in the first data subsection."
2883 .ascii "This lives in the first text section,"
2884 .ascii "immediately following the asterisk (*)."
2887 Each section has a @dfn{location counter} incremented by one for every byte
2888 assembled into that section. Because subsections are merely a convenience
2889 restricted to @command{@value{AS}} there is no concept of a subsection location
2890 counter. There is no way to directly manipulate a location counter---but the
2891 @code{.align} directive changes it, and any label definition captures its
2892 current value. The location counter of the section where statements are being
2893 assembled is said to be the @dfn{active} location counter.
2896 @section bss Section
2899 @cindex common variable storage
2900 The bss section is used for local common variable storage.
2901 You may allocate address space in the bss section, but you may
2902 not dictate data to load into it before your program executes. When
2903 your program starts running, all the contents of the bss
2904 section are zeroed bytes.
2906 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2907 @ref{Lcomm,,@code{.lcomm}}.
2909 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2910 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2913 When assembling for a target which supports multiple sections, such as ELF or
2914 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2915 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2916 section. Typically the section will only contain symbol definitions and
2917 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2924 Symbols are a central concept: the programmer uses symbols to name
2925 things, the linker uses symbols to link, and the debugger uses symbols
2929 @cindex debuggers, and symbol order
2930 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2931 the same order they were declared. This may break some debuggers.
2936 * Setting Symbols:: Giving Symbols Other Values
2937 * Symbol Names:: Symbol Names
2938 * Dot:: The Special Dot Symbol
2939 * Symbol Attributes:: Symbol Attributes
2946 A @dfn{label} is written as a symbol immediately followed by a colon
2947 @samp{:}. The symbol then represents the current value of the
2948 active location counter, and is, for example, a suitable instruction
2949 operand. You are warned if you use the same symbol to represent two
2950 different locations: the first definition overrides any other
2954 On the HPPA, the usual form for a label need not be immediately followed by a
2955 colon, but instead must start in column zero. Only one label may be defined on
2956 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2957 provides a special directive @code{.label} for defining labels more flexibly.
2960 @node Setting Symbols
2961 @section Giving Symbols Other Values
2963 @cindex assigning values to symbols
2964 @cindex symbol values, assigning
2965 A symbol can be given an arbitrary value by writing a symbol, followed
2966 by an equals sign @samp{=}, followed by an expression
2967 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2968 directive. @xref{Set,,@code{.set}}.
2971 @section Symbol Names
2973 @cindex symbol names
2974 @cindex names, symbol
2975 @ifclear SPECIAL-SYMS
2976 Symbol names begin with a letter or with one of @samp{._}. On most
2977 machines, you can also use @code{$} in symbol names; exceptions are
2978 noted in @ref{Machine Dependencies}. That character may be followed by any
2979 string of digits, letters, dollar signs (unless otherwise noted in
2980 @ref{Machine Dependencies}), and underscores.
2983 For the AMD 29K family, @samp{?} is also allowed in the
2984 body of a symbol name, though not at its beginning.
2989 Symbol names begin with a letter or with one of @samp{._}. On the
2991 H8/500, you can also use @code{$} in symbol names. That character may
2992 be followed by any string of digits, letters, dollar signs (save on the
2993 H8/300), and underscores.
2997 Case of letters is significant: @code{foo} is a different symbol name
3000 Each symbol has exactly one name. Each name in an assembly language program
3001 refers to exactly one symbol. You may use that symbol name any number of times
3004 @subheading Local Symbol Names
3006 @cindex local symbol names
3007 @cindex symbol names, local
3008 @cindex temporary symbol names
3009 @cindex symbol names, temporary
3010 Local symbols help compilers and programmers use names temporarily.
3011 They create symbols which are guaranteed to be unique over the entire scope of
3012 the input source code and which can be referred to by a simple notation.
3013 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3014 represents any positive integer). To refer to the most recent previous
3015 definition of that symbol write @samp{@b{N}b}, using the same number as when
3016 you defined the label. To refer to the next definition of a local label, write
3017 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3020 There is no restriction on how you can use these labels, and you can reuse them
3021 too. So that it is possible to repeatedly define the same local label (using
3022 the same number @samp{@b{N}}), although you can only refer to the most recently
3023 defined local label of that number (for a backwards reference) or the next
3024 definition of a specific local label for a forward reference. It is also worth
3025 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3026 implemented in a slightly more efficient manner than the others.
3037 Which is the equivalent of:
3040 label_1: branch label_3
3041 label_2: branch label_1
3042 label_3: branch label_4
3043 label_4: branch label_3
3046 Local symbol names are only a notational device. They are immediately
3047 transformed into more conventional symbol names before the assembler uses them.
3048 The symbol names stored in the symbol table, appearing in error messages and
3049 optionally emitted to the object file. The names are constructed using these
3054 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3055 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3056 used for symbols you are never intended to see. If you use the
3057 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3058 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3059 you may use them in debugging.
3062 This is the number that was used in the local label definition. So if the
3063 label is written @samp{55:} then the number is @samp{55}.
3066 This unusual character is included so you do not accidentally invent a symbol
3067 of the same name. The character has ASCII value of @samp{\002} (control-B).
3069 @item @emph{ordinal number}
3070 This is a serial number to keep the labels distinct. The first definition of
3071 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3072 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3073 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3076 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3077 @code{3:} is named @code{L3@kbd{C-B}44}.
3079 @subheading Dollar Local Labels
3080 @cindex dollar local symbols
3082 @code{@value{AS}} also supports an even more local form of local labels called
3083 dollar labels. These labels go out of scope (ie they become undefined) as soon
3084 as a non-local label is defined. Thus they remain valid for only a small
3085 region of the input source code. Normal local labels, by contrast, remain in
3086 scope for the entire file, or until they are redefined by another occurrence of
3087 the same local label.
3089 Dollar labels are defined in exactly the same way as ordinary local labels,
3090 except that instead of being terminated by a colon, they are terminated by a
3091 dollar sign. eg @samp{@b{55$}}.
3093 They can also be distinguished from ordinary local labels by their transformed
3094 name which uses ASCII character @samp{\001} (control-A) as the magic character
3095 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3096 is named @samp{L6@kbd{C-A}5}.
3099 @section The Special Dot Symbol
3101 @cindex dot (symbol)
3102 @cindex @code{.} (symbol)
3103 @cindex current address
3104 @cindex location counter
3105 The special symbol @samp{.} refers to the current address that
3106 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3107 .long .} defines @code{melvin} to contain its own address.
3108 Assigning a value to @code{.} is treated the same as a @code{.org}
3109 directive. Thus, the expression @samp{.=.+4} is the same as saying
3110 @ifclear no-space-dir
3119 @node Symbol Attributes
3120 @section Symbol Attributes
3122 @cindex symbol attributes
3123 @cindex attributes, symbol
3124 Every symbol has, as well as its name, the attributes ``Value'' and
3125 ``Type''. Depending on output format, symbols can also have auxiliary
3128 The detailed definitions are in @file{a.out.h}.
3131 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3132 all these attributes, and probably won't warn you. This makes the
3133 symbol an externally defined symbol, which is generally what you
3137 * Symbol Value:: Value
3138 * Symbol Type:: Type
3141 * a.out Symbols:: Symbol Attributes: @code{a.out}
3145 * a.out Symbols:: Symbol Attributes: @code{a.out}
3148 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3153 * COFF Symbols:: Symbol Attributes for COFF
3156 * SOM Symbols:: Symbol Attributes for SOM
3163 @cindex value of a symbol
3164 @cindex symbol value
3165 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3166 location in the text, data, bss or absolute sections the value is the
3167 number of addresses from the start of that section to the label.
3168 Naturally for text, data and bss sections the value of a symbol changes
3169 as @code{@value{LD}} changes section base addresses during linking. Absolute
3170 symbols' values do not change during linking: that is why they are
3173 The value of an undefined symbol is treated in a special way. If it is
3174 0 then the symbol is not defined in this assembler source file, and
3175 @code{@value{LD}} tries to determine its value from other files linked into the
3176 same program. You make this kind of symbol simply by mentioning a symbol
3177 name without defining it. A non-zero value represents a @code{.comm}
3178 common declaration. The value is how much common storage to reserve, in
3179 bytes (addresses). The symbol refers to the first address of the
3185 @cindex type of a symbol
3187 The type attribute of a symbol contains relocation (section)
3188 information, any flag settings indicating that a symbol is external, and
3189 (optionally), other information for linkers and debuggers. The exact
3190 format depends on the object-code output format in use.
3195 @c The following avoids a "widow" subsection title. @group would be
3196 @c better if it were available outside examples.
3199 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3201 @cindex @code{b.out} symbol attributes
3202 @cindex symbol attributes, @code{b.out}
3203 These symbol attributes appear only when @command{@value{AS}} is configured for
3204 one of the Berkeley-descended object output formats---@code{a.out} or
3210 @subsection Symbol Attributes: @code{a.out}
3212 @cindex @code{a.out} symbol attributes
3213 @cindex symbol attributes, @code{a.out}
3219 @subsection Symbol Attributes: @code{a.out}
3221 @cindex @code{a.out} symbol attributes
3222 @cindex symbol attributes, @code{a.out}
3226 * Symbol Desc:: Descriptor
3227 * Symbol Other:: Other
3231 @subsubsection Descriptor
3233 @cindex descriptor, of @code{a.out} symbol
3234 This is an arbitrary 16-bit value. You may establish a symbol's
3235 descriptor value by using a @code{.desc} statement
3236 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3237 @command{@value{AS}}.
3240 @subsubsection Other
3242 @cindex other attribute, of @code{a.out} symbol
3243 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3248 @subsection Symbol Attributes for COFF
3250 @cindex COFF symbol attributes
3251 @cindex symbol attributes, COFF
3253 The COFF format supports a multitude of auxiliary symbol attributes;
3254 like the primary symbol attributes, they are set between @code{.def} and
3255 @code{.endef} directives.
3257 @subsubsection Primary Attributes
3259 @cindex primary attributes, COFF symbols
3260 The symbol name is set with @code{.def}; the value and type,
3261 respectively, with @code{.val} and @code{.type}.
3263 @subsubsection Auxiliary Attributes
3265 @cindex auxiliary attributes, COFF symbols
3266 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3267 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3268 information for COFF.
3273 @subsection Symbol Attributes for SOM
3275 @cindex SOM symbol attributes
3276 @cindex symbol attributes, SOM
3278 The SOM format for the HPPA supports a multitude of symbol attributes set with
3279 the @code{.EXPORT} and @code{.IMPORT} directives.
3281 The attributes are described in @cite{HP9000 Series 800 Assembly
3282 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3283 @code{EXPORT} assembler directive documentation.
3287 @chapter Expressions
3291 @cindex numeric values
3292 An @dfn{expression} specifies an address or numeric value.
3293 Whitespace may precede and/or follow an expression.
3295 The result of an expression must be an absolute number, or else an offset into
3296 a particular section. If an expression is not absolute, and there is not
3297 enough information when @command{@value{AS}} sees the expression to know its
3298 section, a second pass over the source program might be necessary to interpret
3299 the expression---but the second pass is currently not implemented.
3300 @command{@value{AS}} aborts with an error message in this situation.
3303 * Empty Exprs:: Empty Expressions
3304 * Integer Exprs:: Integer Expressions
3308 @section Empty Expressions
3310 @cindex empty expressions
3311 @cindex expressions, empty
3312 An empty expression has no value: it is just whitespace or null.
3313 Wherever an absolute expression is required, you may omit the
3314 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3315 is compatible with other assemblers.
3318 @section Integer Expressions
3320 @cindex integer expressions
3321 @cindex expressions, integer
3322 An @dfn{integer expression} is one or more @emph{arguments} delimited
3323 by @emph{operators}.
3326 * Arguments:: Arguments
3327 * Operators:: Operators
3328 * Prefix Ops:: Prefix Operators
3329 * Infix Ops:: Infix Operators
3333 @subsection Arguments
3335 @cindex expression arguments
3336 @cindex arguments in expressions
3337 @cindex operands in expressions
3338 @cindex arithmetic operands
3339 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3340 contexts arguments are sometimes called ``arithmetic operands''. In
3341 this manual, to avoid confusing them with the ``instruction operands'' of
3342 the machine language, we use the term ``argument'' to refer to parts of
3343 expressions only, reserving the word ``operand'' to refer only to machine
3344 instruction operands.
3346 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3347 @var{section} is one of text, data, bss, absolute,
3348 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3351 Numbers are usually integers.
3353 A number can be a flonum or bignum. In this case, you are warned
3354 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3355 these 32 bits are an integer. You may write integer-manipulating
3356 instructions that act on exotic constants, compatible with other
3359 @cindex subexpressions
3360 Subexpressions are a left parenthesis @samp{(} followed by an integer
3361 expression, followed by a right parenthesis @samp{)}; or a prefix
3362 operator followed by an argument.
3365 @subsection Operators
3367 @cindex operators, in expressions
3368 @cindex arithmetic functions
3369 @cindex functions, in expressions
3370 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3371 operators are followed by an argument. Infix operators appear
3372 between their arguments. Operators may be preceded and/or followed by
3376 @subsection Prefix Operator
3378 @cindex prefix operators
3379 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3380 one argument, which must be absolute.
3382 @c the tex/end tex stuff surrounding this small table is meant to make
3383 @c it align, on the printed page, with the similar table in the next
3384 @c section (which is inside an enumerate).
3386 \global\advance\leftskip by \itemindent
3391 @dfn{Negation}. Two's complement negation.
3393 @dfn{Complementation}. Bitwise not.
3397 \global\advance\leftskip by -\itemindent
3401 @subsection Infix Operators
3403 @cindex infix operators
3404 @cindex operators, permitted arguments
3405 @dfn{Infix operators} take two arguments, one on either side. Operators
3406 have precedence, but operations with equal precedence are performed left
3407 to right. Apart from @code{+} or @option{-}, both arguments must be
3408 absolute, and the result is absolute.
3411 @cindex operator precedence
3412 @cindex precedence of operators
3419 @dfn{Multiplication}.
3422 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3429 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3433 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3437 Intermediate precedence
3442 @dfn{Bitwise Inclusive Or}.
3448 @dfn{Bitwise Exclusive Or}.
3451 @dfn{Bitwise Or Not}.
3458 @cindex addition, permitted arguments
3459 @cindex plus, permitted arguments
3460 @cindex arguments for addition
3462 @dfn{Addition}. If either argument is absolute, the result has the section of
3463 the other argument. You may not add together arguments from different
3466 @cindex subtraction, permitted arguments
3467 @cindex minus, permitted arguments
3468 @cindex arguments for subtraction
3470 @dfn{Subtraction}. If the right argument is absolute, the
3471 result has the section of the left argument.
3472 If both arguments are in the same section, the result is absolute.
3473 You may not subtract arguments from different sections.
3474 @c FIXME is there still something useful to say about undefined - undefined ?
3476 @cindex comparison expressions
3477 @cindex expressions, comparison
3481 @dfn{Is Not Equal To}
3485 @dfn{Is Greater Than}
3487 @dfn{Is Greater Than Or Equal To}
3489 @dfn{Is Less Than Or Equal To}
3491 The comparison operators can be used as infix operators. A true results has a
3492 value of -1 whereas a false result has a value of 0. Note, these operators
3493 perform signed comparisons.
3496 @item Lowest Precedence
3505 These two logical operations can be used to combine the results of sub
3506 expressions. Note, unlike the comparison operators a true result returns a
3507 value of 1 but a false results does still return 0. Also note that the logical
3508 or operator has a slightly lower precedence than logical and.
3513 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3514 address; you can only have a defined section in one of the two arguments.
3517 @chapter Assembler Directives
3519 @cindex directives, machine independent
3520 @cindex pseudo-ops, machine independent
3521 @cindex machine independent directives
3522 All assembler directives have names that begin with a period (@samp{.}).
3523 The rest of the name is letters, usually in lower case.
3525 This chapter discusses directives that are available regardless of the
3526 target machine configuration for the @sc{gnu} assembler.
3528 Some machine configurations provide additional directives.
3529 @xref{Machine Dependencies}.
3532 @ifset machine-directives
3533 @xref{Machine Dependencies} for additional directives.
3538 * Abort:: @code{.abort}
3540 * ABORT:: @code{.ABORT}
3543 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3544 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3545 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3546 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3547 * Byte:: @code{.byte @var{expressions}}
3548 * Comm:: @code{.comm @var{symbol} , @var{length} }
3549 * Data:: @code{.data @var{subsection}}
3551 * Def:: @code{.def @var{name}}
3554 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3560 * Double:: @code{.double @var{flonums}}
3561 * Eject:: @code{.eject}
3562 * Else:: @code{.else}
3563 * Elseif:: @code{.elseif}
3566 * Endef:: @code{.endef}
3569 * Endfunc:: @code{.endfunc}
3570 * Endif:: @code{.endif}
3571 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3572 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3574 * Exitm:: @code{.exitm}
3575 * Extern:: @code{.extern}
3576 * Fail:: @code{.fail}
3577 @ifclear no-file-dir
3578 * File:: @code{.file @var{string}}
3581 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3582 * Float:: @code{.float @var{flonums}}
3583 * Func:: @code{.func}
3584 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3586 * Hidden:: @code{.hidden @var{names}}
3589 * hword:: @code{.hword @var{expressions}}
3590 * Ident:: @code{.ident}
3591 * If:: @code{.if @var{absolute expression}}
3592 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3593 * Include:: @code{.include "@var{file}"}
3594 * Int:: @code{.int @var{expressions}}
3596 * Internal:: @code{.internal @var{names}}
3599 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3600 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3601 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3602 * Lflags:: @code{.lflags}
3603 @ifclear no-line-dir
3604 * Line:: @code{.line @var{line-number}}
3607 * Ln:: @code{.ln @var{line-number}}
3608 * Linkonce:: @code{.linkonce [@var{type}]}
3609 * List:: @code{.list}
3610 * Long:: @code{.long @var{expressions}}
3612 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3615 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3616 * MRI:: @code{.mri @var{val}}
3617 * Nolist:: @code{.nolist}
3618 * Octa:: @code{.octa @var{bignums}}
3619 * Org:: @code{.org @var{new-lc} , @var{fill}}
3620 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3622 * PopSection:: @code{.popsection}
3623 * Previous:: @code{.previous}
3626 * Print:: @code{.print @var{string}}
3628 * Protected:: @code{.protected @var{names}}
3631 * Psize:: @code{.psize @var{lines}, @var{columns}}
3632 * Purgem:: @code{.purgem @var{name}}
3634 * PushSection:: @code{.pushsection @var{name}}
3637 * Quad:: @code{.quad @var{bignums}}
3638 * Rept:: @code{.rept @var{count}}
3639 * Sbttl:: @code{.sbttl "@var{subheading}"}
3641 * Scl:: @code{.scl @var{class}}
3642 * Section:: @code{.section @var{name}, @var{subsection}}
3645 * Set:: @code{.set @var{symbol}, @var{expression}}
3646 * Short:: @code{.short @var{expressions}}
3647 * Single:: @code{.single @var{flonums}}
3648 * Size:: @code{.size [@var{name} , @var{expression}]}
3649 * Skip:: @code{.skip @var{size} , @var{fill}}
3650 * Sleb128:: @code{.sleb128 @var{expressions}}
3651 * Space:: @code{.space @var{size} , @var{fill}}
3653 * Stab:: @code{.stabd, .stabn, .stabs}
3656 * String:: @code{.string "@var{str}"}
3657 * Struct:: @code{.struct @var{expression}}
3659 * SubSection:: @code{.subsection}
3660 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3664 * Tag:: @code{.tag @var{structname}}
3667 * Text:: @code{.text @var{subsection}}
3668 * Title:: @code{.title "@var{heading}"}
3669 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3670 * Uleb128:: @code{.uleb128 @var{expressions}}
3672 * Val:: @code{.val @var{addr}}
3676 * Version:: @code{.version "@var{string}"}
3677 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3678 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3679 * Weak:: @code{.weak @var{names}}
3682 * Word:: @code{.word @var{expressions}}
3683 * Deprecated:: Deprecated Directives
3687 @section @code{.abort}
3689 @cindex @code{abort} directive
3690 @cindex stopping the assembly
3691 This directive stops the assembly immediately. It is for
3692 compatibility with other assemblers. The original idea was that the
3693 assembly language source would be piped into the assembler. If the sender
3694 of the source quit, it could use this directive tells @command{@value{AS}} to
3695 quit also. One day @code{.abort} will not be supported.
3699 @section @code{.ABORT}
3701 @cindex @code{ABORT} directive
3702 When producing COFF output, @command{@value{AS}} accepts this directive as a
3703 synonym for @samp{.abort}.
3706 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3712 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3714 @cindex padding the location counter
3715 @cindex @code{align} directive
3716 Pad the location counter (in the current subsection) to a particular storage
3717 boundary. The first expression (which must be absolute) is the alignment
3718 required, as described below.
3720 The second expression (also absolute) gives the fill value to be stored in the
3721 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3722 padding bytes are normally zero. However, on some systems, if the section is
3723 marked as containing code and the fill value is omitted, the space is filled
3724 with no-op instructions.
3726 The third expression is also absolute, and is also optional. If it is present,
3727 it is the maximum number of bytes that should be skipped by this alignment
3728 directive. If doing the alignment would require skipping more bytes than the
3729 specified maximum, then the alignment is not done at all. You can omit the
3730 fill value (the second argument) entirely by simply using two commas after the
3731 required alignment; this can be useful if you want the alignment to be filled
3732 with no-op instructions when appropriate.
3734 The way the required alignment is specified varies from system to system.
3735 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3737 the first expression is the
3738 alignment request in bytes. For example @samp{.align 8} advances
3739 the location counter until it is a multiple of 8. If the location counter
3740 is already a multiple of 8, no change is needed.
3742 For other systems, including the i386 using a.out format, and the arm and
3743 strongarm, it is the
3744 number of low-order zero bits the location counter must have after
3745 advancement. For example @samp{.align 3} advances the location
3746 counter until it a multiple of 8. If the location counter is already a
3747 multiple of 8, no change is needed.
3749 This inconsistency is due to the different behaviors of the various
3750 native assemblers for these systems which GAS must emulate.
3751 GAS also provides @code{.balign} and @code{.p2align} directives,
3752 described later, which have a consistent behavior across all
3753 architectures (but are specific to GAS).
3756 @section @code{.ascii "@var{string}"}@dots{}
3758 @cindex @code{ascii} directive
3759 @cindex string literals
3760 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3761 separated by commas. It assembles each string (with no automatic
3762 trailing zero byte) into consecutive addresses.
3765 @section @code{.asciz "@var{string}"}@dots{}
3767 @cindex @code{asciz} directive
3768 @cindex zero-terminated strings
3769 @cindex null-terminated strings
3770 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3771 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3774 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3776 @cindex padding the location counter given number of bytes
3777 @cindex @code{balign} directive
3778 Pad the location counter (in the current subsection) to a particular
3779 storage boundary. The first expression (which must be absolute) is the
3780 alignment request in bytes. For example @samp{.balign 8} advances
3781 the location counter until it is a multiple of 8. If the location counter
3782 is already a multiple of 8, no change is needed.
3784 The second expression (also absolute) gives the fill value to be stored in the
3785 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3786 padding bytes are normally zero. However, on some systems, if the section is
3787 marked as containing code and the fill value is omitted, the space is filled
3788 with no-op instructions.
3790 The third expression is also absolute, and is also optional. If it is present,
3791 it is the maximum number of bytes that should be skipped by this alignment
3792 directive. If doing the alignment would require skipping more bytes than the
3793 specified maximum, then the alignment is not done at all. You can omit the
3794 fill value (the second argument) entirely by simply using two commas after the
3795 required alignment; this can be useful if you want the alignment to be filled
3796 with no-op instructions when appropriate.
3798 @cindex @code{balignw} directive
3799 @cindex @code{balignl} directive
3800 The @code{.balignw} and @code{.balignl} directives are variants of the
3801 @code{.balign} directive. The @code{.balignw} directive treats the fill
3802 pattern as a two byte word value. The @code{.balignl} directives treats the
3803 fill pattern as a four byte longword value. For example, @code{.balignw
3804 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3805 filled in with the value 0x368d (the exact placement of the bytes depends upon
3806 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3810 @section @code{.byte @var{expressions}}
3812 @cindex @code{byte} directive
3813 @cindex integers, one byte
3814 @code{.byte} expects zero or more expressions, separated by commas.
3815 Each expression is assembled into the next byte.
3818 @section @code{.comm @var{symbol} , @var{length} }
3820 @cindex @code{comm} directive
3821 @cindex symbol, common
3822 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3823 common symbol in one object file may be merged with a defined or common symbol
3824 of the same name in another object file. If @code{@value{LD}} does not see a
3825 definition for the symbol--just one or more common symbols--then it will
3826 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3827 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3828 the same name, and they do not all have the same size, it will allocate space
3829 using the largest size.
3832 When using ELF, the @code{.comm} directive takes an optional third argument.
3833 This is the desired alignment of the symbol, specified as a byte boundary (for
3834 example, an alignment of 16 means that the least significant 4 bits of the
3835 address should be zero). The alignment must be an absolute expression, and it
3836 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3837 for the common symbol, it will use the alignment when placing the symbol. If
3838 no alignment is specified, @command{@value{AS}} will set the alignment to the
3839 largest power of two less than or equal to the size of the symbol, up to a
3844 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3845 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3849 @section @code{.data @var{subsection}}
3851 @cindex @code{data} directive
3852 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3853 end of the data subsection numbered @var{subsection} (which is an
3854 absolute expression). If @var{subsection} is omitted, it defaults
3859 @section @code{.def @var{name}}
3861 @cindex @code{def} directive
3862 @cindex COFF symbols, debugging
3863 @cindex debugging COFF symbols
3864 Begin defining debugging information for a symbol @var{name}; the
3865 definition extends until the @code{.endef} directive is encountered.
3868 This directive is only observed when @command{@value{AS}} is configured for COFF
3869 format output; when producing @code{b.out}, @samp{.def} is recognized,
3876 @section @code{.desc @var{symbol}, @var{abs-expression}}
3878 @cindex @code{desc} directive
3879 @cindex COFF symbol descriptor
3880 @cindex symbol descriptor, COFF
3881 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3882 to the low 16 bits of an absolute expression.
3885 The @samp{.desc} directive is not available when @command{@value{AS}} is
3886 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3887 object format. For the sake of compatibility, @command{@value{AS}} accepts
3888 it, but produces no output, when configured for COFF.
3894 @section @code{.dim}
3896 @cindex @code{dim} directive
3897 @cindex COFF auxiliary symbol information
3898 @cindex auxiliary symbol information, COFF
3899 This directive is generated by compilers to include auxiliary debugging
3900 information in the symbol table. It is only permitted inside
3901 @code{.def}/@code{.endef} pairs.
3904 @samp{.dim} is only meaningful when generating COFF format output; when
3905 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3911 @section @code{.double @var{flonums}}
3913 @cindex @code{double} directive
3914 @cindex floating point numbers (double)
3915 @code{.double} expects zero or more flonums, separated by commas. It
3916 assembles floating point numbers.
3918 The exact kind of floating point numbers emitted depends on how
3919 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3923 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3924 in @sc{ieee} format.
3929 @section @code{.eject}
3931 @cindex @code{eject} directive
3932 @cindex new page, in listings
3933 @cindex page, in listings
3934 @cindex listing control: new page
3935 Force a page break at this point, when generating assembly listings.
3938 @section @code{.else}
3940 @cindex @code{else} directive
3941 @code{.else} is part of the @command{@value{AS}} support for conditional
3942 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3943 of code to be assembled if the condition for the preceding @code{.if}
3947 @section @code{.elseif}
3949 @cindex @code{elseif} directive
3950 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3951 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3952 @code{.if} block that would otherwise fill the entire @code{.else} section.
3955 @section @code{.end}
3957 @cindex @code{end} directive
3958 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3959 process anything in the file past the @code{.end} directive.
3963 @section @code{.endef}
3965 @cindex @code{endef} directive
3966 This directive flags the end of a symbol definition begun with
3970 @samp{.endef} is only meaningful when generating COFF format output; if
3971 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3972 directive but ignores it.
3977 @section @code{.endfunc}
3978 @cindex @code{endfunc} directive
3979 @code{.endfunc} marks the end of a function specified with @code{.func}.
3982 @section @code{.endif}
3984 @cindex @code{endif} directive
3985 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3986 it marks the end of a block of code that is only assembled
3987 conditionally. @xref{If,,@code{.if}}.
3990 @section @code{.equ @var{symbol}, @var{expression}}
3992 @cindex @code{equ} directive
3993 @cindex assigning values to symbols
3994 @cindex symbols, assigning values to
3995 This directive sets the value of @var{symbol} to @var{expression}.
3996 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3999 The syntax for @code{equ} on the HPPA is
4000 @samp{@var{symbol} .equ @var{expression}}.
4004 @section @code{.equiv @var{symbol}, @var{expression}}
4005 @cindex @code{equiv} directive
4006 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4007 the assembler will signal an error if @var{symbol} is already defined.
4009 Except for the contents of the error message, this is roughly equivalent to
4018 @section @code{.err}
4019 @cindex @code{err} directive
4020 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4021 message and, unless the @option{-Z} option was used, it will not generate an
4022 object file. This can be used to signal error an conditionally compiled code.
4025 @section @code{.exitm}
4026 Exit early from the current macro definition. @xref{Macro}.
4029 @section @code{.extern}
4031 @cindex @code{extern} directive
4032 @code{.extern} is accepted in the source program---for compatibility
4033 with other assemblers---but it is ignored. @command{@value{AS}} treats
4034 all undefined symbols as external.
4037 @section @code{.fail @var{expression}}
4039 @cindex @code{fail} directive
4040 Generates an error or a warning. If the value of the @var{expression} is 500
4041 or more, @command{@value{AS}} will print a warning message. If the value is less
4042 than 500, @command{@value{AS}} will print an error message. The message will
4043 include the value of @var{expression}. This can occasionally be useful inside
4044 complex nested macros or conditional assembly.
4046 @ifclear no-file-dir
4048 @section @code{.file @var{string}}
4050 @cindex @code{file} directive
4051 @cindex logical file name
4052 @cindex file name, logical
4053 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4054 file. @var{string} is the new file name. In general, the filename is
4055 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4056 to specify an empty file name, you must give the quotes--@code{""}. This
4057 statement may go away in future: it is only recognized to be compatible with
4058 old @command{@value{AS}} programs.
4060 In some configurations of @command{@value{AS}}, @code{.file} has already been
4061 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4066 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4068 @cindex @code{fill} directive
4069 @cindex writing patterns in memory
4070 @cindex patterns, writing in memory
4071 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4072 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4073 may be zero or more. @var{Size} may be zero or more, but if it is
4074 more than 8, then it is deemed to have the value 8, compatible with
4075 other people's assemblers. The contents of each @var{repeat} bytes
4076 is taken from an 8-byte number. The highest order 4 bytes are
4077 zero. The lowest order 4 bytes are @var{value} rendered in the
4078 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4079 Each @var{size} bytes in a repetition is taken from the lowest order
4080 @var{size} bytes of this number. Again, this bizarre behavior is
4081 compatible with other people's assemblers.
4083 @var{size} and @var{value} are optional.
4084 If the second comma and @var{value} are absent, @var{value} is
4085 assumed zero. If the first comma and following tokens are absent,
4086 @var{size} is assumed to be 1.
4089 @section @code{.float @var{flonums}}
4091 @cindex floating point numbers (single)
4092 @cindex @code{float} directive
4093 This directive assembles zero or more flonums, separated by commas. It
4094 has the same effect as @code{.single}.
4096 The exact kind of floating point numbers emitted depends on how
4097 @command{@value{AS}} is configured.
4098 @xref{Machine Dependencies}.
4102 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4103 in @sc{ieee} format.
4108 @section @code{.func @var{name}[,@var{label}]}
4109 @cindex @code{func} directive
4110 @code{.func} emits debugging information to denote function @var{name}, and
4111 is ignored unless the file is assembled with debugging enabled.
4112 Only @samp{--gstabs} is currently supported.
4113 @var{label} is the entry point of the function and if omitted @var{name}
4114 prepended with the @samp{leading char} is used.
4115 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4116 All functions are currently defined to have @code{void} return type.
4117 The function must be terminated with @code{.endfunc}.
4120 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4122 @cindex @code{global} directive
4123 @cindex symbol, making visible to linker
4124 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4125 @var{symbol} in your partial program, its value is made available to
4126 other partial programs that are linked with it. Otherwise,
4127 @var{symbol} takes its attributes from a symbol of the same name
4128 from another file linked into the same program.
4130 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4131 compatibility with other assemblers.
4134 On the HPPA, @code{.global} is not always enough to make it accessible to other
4135 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4136 @xref{HPPA Directives,, HPPA Assembler Directives}.
4141 @section @code{.hidden @var{names}}
4143 @cindex @code{.hidden} directive
4145 This one of the ELF visibility directives. The other two are
4146 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4147 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4149 This directive overrides the named symbols default visibility (which is set by
4150 their binding: local, global or weak). The directive sets the visibility to
4151 @code{hidden} which means that the symbols are not visible to other components.
4152 Such symbols are always considered to be @code{protected} as well.
4156 @section @code{.hword @var{expressions}}
4158 @cindex @code{hword} directive
4159 @cindex integers, 16-bit
4160 @cindex numbers, 16-bit
4161 @cindex sixteen bit integers
4162 This expects zero or more @var{expressions}, and emits
4163 a 16 bit number for each.
4166 This directive is a synonym for @samp{.short}; depending on the target
4167 architecture, it may also be a synonym for @samp{.word}.
4171 This directive is a synonym for @samp{.short}.
4174 This directive is a synonym for both @samp{.short} and @samp{.word}.
4179 @section @code{.ident}
4181 @cindex @code{ident} directive
4182 This directive is used by some assemblers to place tags in object files.
4183 @command{@value{AS}} simply accepts the directive for source-file
4184 compatibility with such assemblers, but does not actually emit anything
4188 @section @code{.if @var{absolute expression}}
4190 @cindex conditional assembly
4191 @cindex @code{if} directive
4192 @code{.if} marks the beginning of a section of code which is only
4193 considered part of the source program being assembled if the argument
4194 (which must be an @var{absolute expression}) is non-zero. The end of
4195 the conditional section of code must be marked by @code{.endif}
4196 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4197 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4198 If you have several conditions to check, @code{.elseif} may be used to avoid
4199 nesting blocks if/else within each subsequent @code{.else} block.
4201 The following variants of @code{.if} are also supported:
4203 @cindex @code{ifdef} directive
4204 @item .ifdef @var{symbol}
4205 Assembles the following section of code if the specified @var{symbol}
4208 @cindex @code{ifc} directive
4209 @item .ifc @var{string1},@var{string2}
4210 Assembles the following section of code if the two strings are the same. The
4211 strings may be optionally quoted with single quotes. If they are not quoted,
4212 the first string stops at the first comma, and the second string stops at the
4213 end of the line. Strings which contain whitespace should be quoted. The
4214 string comparison is case sensitive.
4216 @cindex @code{ifeq} directive
4217 @item .ifeq @var{absolute expression}
4218 Assembles the following section of code if the argument is zero.
4220 @cindex @code{ifeqs} directive
4221 @item .ifeqs @var{string1},@var{string2}
4222 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4224 @cindex @code{ifge} directive
4225 @item .ifge @var{absolute expression}
4226 Assembles the following section of code if the argument is greater than or
4229 @cindex @code{ifgt} directive
4230 @item .ifgt @var{absolute expression}
4231 Assembles the following section of code if the argument is greater than zero.
4233 @cindex @code{ifle} directive
4234 @item .ifle @var{absolute expression}
4235 Assembles the following section of code if the argument is less than or equal
4238 @cindex @code{iflt} directive
4239 @item .iflt @var{absolute expression}
4240 Assembles the following section of code if the argument is less than zero.
4242 @cindex @code{ifnc} directive
4243 @item .ifnc @var{string1},@var{string2}.
4244 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4245 following section of code if the two strings are not the same.
4247 @cindex @code{ifndef} directive
4248 @cindex @code{ifnotdef} directive
4249 @item .ifndef @var{symbol}
4250 @itemx .ifnotdef @var{symbol}
4251 Assembles the following section of code if the specified @var{symbol}
4252 has not been defined. Both spelling variants are equivalent.
4254 @cindex @code{ifne} directive
4255 @item .ifne @var{absolute expression}
4256 Assembles the following section of code if the argument is not equal to zero
4257 (in other words, this is equivalent to @code{.if}).
4259 @cindex @code{ifnes} directive
4260 @item .ifnes @var{string1},@var{string2}
4261 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4262 following section of code if the two strings are not the same.
4266 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4268 @cindex @code{incbin} directive
4269 @cindex binary files, including
4270 The @code{incbin} directive includes @var{file} verbatim at the current
4271 location. You can control the search paths used with the @samp{-I} command-line
4272 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4275 The @var{skip} argument skips a number of bytes from the start of the
4276 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4277 read. Note that the data is not aligned in any way, so it is the user's
4278 responsibility to make sure that proper alignment is provided both before and
4279 after the @code{incbin} directive.
4282 @section @code{.include "@var{file}"}
4284 @cindex @code{include} directive
4285 @cindex supporting files, including
4286 @cindex files, including
4287 This directive provides a way to include supporting files at specified
4288 points in your source program. The code from @var{file} is assembled as
4289 if it followed the point of the @code{.include}; when the end of the
4290 included file is reached, assembly of the original file continues. You
4291 can control the search paths used with the @samp{-I} command-line option
4292 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4296 @section @code{.int @var{expressions}}
4298 @cindex @code{int} directive
4299 @cindex integers, 32-bit
4300 Expect zero or more @var{expressions}, of any section, separated by commas.
4301 For each expression, emit a number that, at run time, is the value of that
4302 expression. The byte order and bit size of the number depends on what kind
4303 of target the assembly is for.
4307 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4308 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4315 @section @code{.internal @var{names}}
4317 @cindex @code{.internal} directive
4319 This one of the ELF visibility directives. The other two are
4320 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4321 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4323 This directive overrides the named symbols default visibility (which is set by
4324 their binding: local, global or weak). The directive sets the visibility to
4325 @code{internal} which means that the symbols are considered to be @code{hidden}
4326 (ie not visible to other components), and that some extra, processor specific
4327 processing must also be performed upon the symbols as well.
4331 @section @code{.irp @var{symbol},@var{values}}@dots{}
4333 @cindex @code{irp} directive
4334 Evaluate a sequence of statements assigning different values to @var{symbol}.
4335 The sequence of statements starts at the @code{.irp} directive, and is
4336 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4337 set to @var{value}, and the sequence of statements is assembled. If no
4338 @var{value} is listed, the sequence of statements is assembled once, with
4339 @var{symbol} set to the null string. To refer to @var{symbol} within the
4340 sequence of statements, use @var{\symbol}.
4342 For example, assembling
4350 is equivalent to assembling
4359 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4361 @cindex @code{irpc} directive
4362 Evaluate a sequence of statements assigning different values to @var{symbol}.
4363 The sequence of statements starts at the @code{.irpc} directive, and is
4364 terminated by an @code{.endr} directive. For each character in @var{value},
4365 @var{symbol} is set to the character, and the sequence of statements is
4366 assembled. If no @var{value} is listed, the sequence of statements is
4367 assembled once, with @var{symbol} set to the null string. To refer to
4368 @var{symbol} within the sequence of statements, use @var{\symbol}.
4370 For example, assembling
4378 is equivalent to assembling
4387 @section @code{.lcomm @var{symbol} , @var{length}}
4389 @cindex @code{lcomm} directive
4390 @cindex local common symbols
4391 @cindex symbols, local common
4392 Reserve @var{length} (an absolute expression) bytes for a local common
4393 denoted by @var{symbol}. The section and value of @var{symbol} are
4394 those of the new local common. The addresses are allocated in the bss
4395 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4396 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4397 not visible to @code{@value{LD}}.
4400 Some targets permit a third argument to be used with @code{.lcomm}. This
4401 argument specifies the desired alignment of the symbol in the bss section.
4405 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4406 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4410 @section @code{.lflags}
4412 @cindex @code{lflags} directive (ignored)
4413 @command{@value{AS}} accepts this directive, for compatibility with other
4414 assemblers, but ignores it.
4416 @ifclear no-line-dir
4418 @section @code{.line @var{line-number}}
4420 @cindex @code{line} directive
4424 @section @code{.ln @var{line-number}}
4426 @cindex @code{ln} directive
4428 @cindex logical line number
4430 Change the logical line number. @var{line-number} must be an absolute
4431 expression. The next line has that logical line number. Therefore any other
4432 statements on the current line (after a statement separator character) are
4433 reported as on logical line number @var{line-number} @minus{} 1. One day
4434 @command{@value{AS}} will no longer support this directive: it is recognized only
4435 for compatibility with existing assembler programs.
4439 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4440 not available; use the synonym @code{.ln} in that context.
4445 @ifclear no-line-dir
4446 Even though this is a directive associated with the @code{a.out} or
4447 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4448 when producing COFF output, and treats @samp{.line} as though it
4449 were the COFF @samp{.ln} @emph{if} it is found outside a
4450 @code{.def}/@code{.endef} pair.
4452 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4453 used by compilers to generate auxiliary symbol information for
4458 @section @code{.linkonce [@var{type}]}
4460 @cindex @code{linkonce} directive
4461 @cindex common sections
4462 Mark the current section so that the linker only includes a single copy of it.
4463 This may be used to include the same section in several different object files,
4464 but ensure that the linker will only include it once in the final output file.
4465 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4466 Duplicate sections are detected based on the section name, so it should be
4469 This directive is only supported by a few object file formats; as of this
4470 writing, the only object file format which supports it is the Portable
4471 Executable format used on Windows NT.
4473 The @var{type} argument is optional. If specified, it must be one of the
4474 following strings. For example:
4478 Not all types may be supported on all object file formats.
4482 Silently discard duplicate sections. This is the default.
4485 Warn if there are duplicate sections, but still keep only one copy.
4488 Warn if any of the duplicates have different sizes.
4491 Warn if any of the duplicates do not have exactly the same contents.
4495 @section @code{.ln @var{line-number}}
4497 @cindex @code{ln} directive
4498 @ifclear no-line-dir
4499 @samp{.ln} is a synonym for @samp{.line}.
4502 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4503 must be an absolute expression. The next line has that logical
4504 line number, so any other statements on the current line (after a
4505 statement separator character @code{;}) are reported as on logical
4506 line number @var{line-number} @minus{} 1.
4509 This directive is accepted, but ignored, when @command{@value{AS}} is
4510 configured for @code{b.out}; its effect is only associated with COFF
4516 @section @code{.mri @var{val}}
4518 @cindex @code{mri} directive
4519 @cindex MRI mode, temporarily
4520 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4521 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4522 affects code assembled until the next @code{.mri} directive, or until the end
4523 of the file. @xref{M, MRI mode, MRI mode}.
4526 @section @code{.list}
4528 @cindex @code{list} directive
4529 @cindex listing control, turning on
4530 Control (in conjunction with the @code{.nolist} directive) whether or
4531 not assembly listings are generated. These two directives maintain an
4532 internal counter (which is zero initially). @code{.list} increments the
4533 counter, and @code{.nolist} decrements it. Assembly listings are
4534 generated whenever the counter is greater than zero.
4536 By default, listings are disabled. When you enable them (with the
4537 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4538 the initial value of the listing counter is one.
4541 @section @code{.long @var{expressions}}
4543 @cindex @code{long} directive
4544 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4547 @c no one seems to know what this is for or whether this description is
4548 @c what it really ought to do
4550 @section @code{.lsym @var{symbol}, @var{expression}}
4552 @cindex @code{lsym} directive
4553 @cindex symbol, not referenced in assembly
4554 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4555 the hash table, ensuring it cannot be referenced by name during the
4556 rest of the assembly. This sets the attributes of the symbol to be
4557 the same as the expression value:
4559 @var{other} = @var{descriptor} = 0
4560 @var{type} = @r{(section of @var{expression})}
4561 @var{value} = @var{expression}
4564 The new symbol is not flagged as external.
4568 @section @code{.macro}
4571 The commands @code{.macro} and @code{.endm} allow you to define macros that
4572 generate assembly output. For example, this definition specifies a macro
4573 @code{sum} that puts a sequence of numbers into memory:
4576 .macro sum from=0, to=5
4585 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4597 @item .macro @var{macname}
4598 @itemx .macro @var{macname} @var{macargs} @dots{}
4599 @cindex @code{macro} directive
4600 Begin the definition of a macro called @var{macname}. If your macro
4601 definition requires arguments, specify their names after the macro name,
4602 separated by commas or spaces. You can supply a default value for any
4603 macro argument by following the name with @samp{=@var{deflt}}. For
4604 example, these are all valid @code{.macro} statements:
4608 Begin the definition of a macro called @code{comm}, which takes no
4611 @item .macro plus1 p, p1
4612 @itemx .macro plus1 p p1
4613 Either statement begins the definition of a macro called @code{plus1},
4614 which takes two arguments; within the macro definition, write
4615 @samp{\p} or @samp{\p1} to evaluate the arguments.
4617 @item .macro reserve_str p1=0 p2
4618 Begin the definition of a macro called @code{reserve_str}, with two
4619 arguments. The first argument has a default value, but not the second.
4620 After the definition is complete, you can call the macro either as
4621 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4622 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4623 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4624 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4627 When you call a macro, you can specify the argument values either by
4628 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4629 @samp{sum to=17, from=9}.
4632 @cindex @code{endm} directive
4633 Mark the end of a macro definition.
4636 @cindex @code{exitm} directive
4637 Exit early from the current macro definition.
4639 @cindex number of macros executed
4640 @cindex macros, count executed
4642 @command{@value{AS}} maintains a counter of how many macros it has
4643 executed in this pseudo-variable; you can copy that number to your
4644 output with @samp{\@@}, but @emph{only within a macro definition}.
4647 @item LOCAL @var{name} [ , @dots{} ]
4648 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4649 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4650 Alternate macro syntax}.
4652 Generate a string replacement for each of the @var{name} arguments, and
4653 replace any instances of @var{name} in each macro expansion. The
4654 replacement string is unique in the assembly, and different for each
4655 separate macro expansion. @code{LOCAL} allows you to write macros that
4656 define symbols, without fear of conflict between separate macro expansions.
4661 @section @code{.nolist}
4663 @cindex @code{nolist} directive
4664 @cindex listing control, turning off
4665 Control (in conjunction with the @code{.list} directive) whether or
4666 not assembly listings are generated. These two directives maintain an
4667 internal counter (which is zero initially). @code{.list} increments the
4668 counter, and @code{.nolist} decrements it. Assembly listings are
4669 generated whenever the counter is greater than zero.
4672 @section @code{.octa @var{bignums}}
4674 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4675 @cindex @code{octa} directive
4676 @cindex integer, 16-byte
4677 @cindex sixteen byte integer
4678 This directive expects zero or more bignums, separated by commas. For each
4679 bignum, it emits a 16-byte integer.
4681 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4682 hence @emph{octa}-word for 16 bytes.
4685 @section @code{.org @var{new-lc} , @var{fill}}
4687 @cindex @code{org} directive
4688 @cindex location counter, advancing
4689 @cindex advancing location counter
4690 @cindex current address, advancing
4691 Advance the location counter of the current section to
4692 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4693 expression with the same section as the current subsection. That is,
4694 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4695 wrong section, the @code{.org} directive is ignored. To be compatible
4696 with former assemblers, if the section of @var{new-lc} is absolute,
4697 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4698 is the same as the current subsection.
4700 @code{.org} may only increase the location counter, or leave it
4701 unchanged; you cannot use @code{.org} to move the location counter
4704 @c double negative used below "not undefined" because this is a specific
4705 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4706 @c section. doc@cygnus.com 18feb91
4707 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4708 may not be undefined. If you really detest this restriction we eagerly await
4709 a chance to share your improved assembler.
4711 Beware that the origin is relative to the start of the section, not
4712 to the start of the subsection. This is compatible with other
4713 people's assemblers.
4715 When the location counter (of the current subsection) is advanced, the
4716 intervening bytes are filled with @var{fill} which should be an
4717 absolute expression. If the comma and @var{fill} are omitted,
4718 @var{fill} defaults to zero.
4721 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4723 @cindex padding the location counter given a power of two
4724 @cindex @code{p2align} directive
4725 Pad the location counter (in the current subsection) to a particular
4726 storage boundary. The first expression (which must be absolute) is the
4727 number of low-order zero bits the location counter must have after
4728 advancement. For example @samp{.p2align 3} advances the location
4729 counter until it a multiple of 8. If the location counter is already a
4730 multiple of 8, no change is needed.
4732 The second expression (also absolute) gives the fill value to be stored in the
4733 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4734 padding bytes are normally zero. However, on some systems, if the section is
4735 marked as containing code and the fill value is omitted, the space is filled
4736 with no-op instructions.
4738 The third expression is also absolute, and is also optional. If it is present,
4739 it is the maximum number of bytes that should be skipped by this alignment
4740 directive. If doing the alignment would require skipping more bytes than the
4741 specified maximum, then the alignment is not done at all. You can omit the
4742 fill value (the second argument) entirely by simply using two commas after the
4743 required alignment; this can be useful if you want the alignment to be filled
4744 with no-op instructions when appropriate.
4746 @cindex @code{p2alignw} directive
4747 @cindex @code{p2alignl} directive
4748 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4749 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4750 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4751 fill pattern as a four byte longword value. For example, @code{.p2alignw
4752 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4753 filled in with the value 0x368d (the exact placement of the bytes depends upon
4754 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4759 @section @code{.previous}
4761 @cindex @code{.previous} directive
4762 @cindex Section Stack
4763 This is one of the ELF section stack manipulation directives. The others are
4764 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4765 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4766 (@pxref{PopSection}).
4768 This directive swaps the current section (and subsection) with most recently
4769 referenced section (and subsection) prior to this one. Multiple
4770 @code{.previous} directives in a row will flip between two sections (and their
4773 In terms of the section stack, this directive swaps the current section with
4774 the top section on the section stack.
4779 @section @code{.popsection}
4781 @cindex @code{.popsection} directive
4782 @cindex Section Stack
4783 This is one of the ELF section stack manipulation directives. The others are
4784 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4785 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4788 This directive replaces the current section (and subsection) with the top
4789 section (and subsection) on the section stack. This section is popped off the
4794 @section @code{.print @var{string}}
4796 @cindex @code{print} directive
4797 @command{@value{AS}} will print @var{string} on the standard output during
4798 assembly. You must put @var{string} in double quotes.
4802 @section @code{.protected @var{names}}
4804 @cindex @code{.protected} directive
4806 This one of the ELF visibility directives. The other two are
4807 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4809 This directive overrides the named symbols default visibility (which is set by
4810 their binding: local, global or weak). The directive sets the visibility to
4811 @code{protected} which means that any references to the symbols from within the
4812 components that defines them must be resolved to the definition in that
4813 component, even if a definition in another component would normally preempt
4818 @section @code{.psize @var{lines} , @var{columns}}
4820 @cindex @code{psize} directive
4821 @cindex listing control: paper size
4822 @cindex paper size, for listings
4823 Use this directive to declare the number of lines---and, optionally, the
4824 number of columns---to use for each page, when generating listings.
4826 If you do not use @code{.psize}, listings use a default line-count
4827 of 60. You may omit the comma and @var{columns} specification; the
4828 default width is 200 columns.
4830 @command{@value{AS}} generates formfeeds whenever the specified number of
4831 lines is exceeded (or whenever you explicitly request one, using
4834 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4835 those explicitly specified with @code{.eject}.
4838 @section @code{.purgem @var{name}}
4840 @cindex @code{purgem} directive
4841 Undefine the macro @var{name}, so that later uses of the string will not be
4842 expanded. @xref{Macro}.
4846 @section @code{.pushsection @var{name} , @var{subsection}}
4848 @cindex @code{.pushsection} directive
4849 @cindex Section Stack
4850 This is one of the ELF section stack manipulation directives. The others are
4851 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4852 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4855 This directive is a synonym for @code{.section}. It pushes the current section
4856 (and subsection) onto the top of the section stack, and then replaces the
4857 current section and subsection with @code{name} and @code{subsection}.
4861 @section @code{.quad @var{bignums}}
4863 @cindex @code{quad} directive
4864 @code{.quad} expects zero or more bignums, separated by commas. For
4865 each bignum, it emits
4867 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4868 warning message; and just takes the lowest order 8 bytes of the bignum.
4869 @cindex eight-byte integer
4870 @cindex integer, 8-byte
4872 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4873 hence @emph{quad}-word for 8 bytes.
4876 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4877 warning message; and just takes the lowest order 16 bytes of the bignum.
4878 @cindex sixteen-byte integer
4879 @cindex integer, 16-byte
4883 @section @code{.rept @var{count}}
4885 @cindex @code{rept} directive
4886 Repeat the sequence of lines between the @code{.rept} directive and the next
4887 @code{.endr} directive @var{count} times.
4889 For example, assembling
4897 is equivalent to assembling
4906 @section @code{.sbttl "@var{subheading}"}
4908 @cindex @code{sbttl} directive
4909 @cindex subtitles for listings
4910 @cindex listing control: subtitle
4911 Use @var{subheading} as the title (third line, immediately after the
4912 title line) when generating assembly listings.
4914 This directive affects subsequent pages, as well as the current page if
4915 it appears within ten lines of the top of a page.
4919 @section @code{.scl @var{class}}
4921 @cindex @code{scl} directive
4922 @cindex symbol storage class (COFF)
4923 @cindex COFF symbol storage class
4924 Set the storage-class value for a symbol. This directive may only be
4925 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4926 whether a symbol is static or external, or it may record further
4927 symbolic debugging information.
4930 The @samp{.scl} directive is primarily associated with COFF output; when
4931 configured to generate @code{b.out} output format, @command{@value{AS}}
4932 accepts this directive but ignores it.
4937 @section @code{.section @var{name}} (COFF version)
4939 @cindex @code{section} directive
4940 @cindex named section
4941 Use the @code{.section} directive to assemble the following code into a section
4944 This directive is only supported for targets that actually support arbitrarily
4945 named sections; on @code{a.out} targets, for example, it is not accepted, even
4946 with a standard @code{a.out} section name.
4948 For COFF targets, the @code{.section} directive is used in one of the following
4952 .section @var{name}[, "@var{flags}"]
4953 .section @var{name}[, @var{subsegment}]
4956 If the optional argument is quoted, it is taken as flags to use for the
4957 section. Each flag is a single character. The following flags are recognized:
4960 bss section (uninitialized data)
4962 section is not loaded
4972 shared section (meaningful for PE targets)
4975 If no flags are specified, the default flags depend upon the section name. If
4976 the section name is not recognized, the default will be for the section to be
4977 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4978 from the section, rather than adding them, so if they are used on their own it
4979 will be as if no flags had been specified at all.
4981 If the optional argument to the @code{.section} directive is not quoted, it is
4982 taken as a subsegment number (@pxref{Sub-Sections}).
4985 @section @code{.section @var{name}} (ELF version)
4987 @cindex @code{section} directive
4988 @cindex named section
4990 @cindex Section Stack
4991 This is one of the ELF section stack manipulation directives. The others are
4992 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4993 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4994 @code{.previous} (@pxref{Previous}).
4997 For ELF targets, the @code{.section} directive is used like this:
5000 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
5003 The optional @var{flags} argument is a quoted string which may contain any
5004 combination of the following characters:
5007 section is allocatable
5011 section is executable
5013 section is mergeable
5015 section contains zero terminated strings
5018 The optional @var{type} argument may contain one of the following constants:
5021 section contains data
5023 section does not contain data (i.e., section only occupies space)
5026 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5027 as well as @var{entsize} argument. Sections with @code{M} flag but not
5028 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5029 long. Sections with both @code{M} and @code{S} must contain zero terminated
5030 strings where each character is @var{entsize} bytes long. The linker may remove
5031 duplicates within sections with the same name, same entity size and same flags.
5033 If no flags are specified, the default flags depend upon the section name. If
5034 the section name is not recognized, the default will be for the section to have
5035 none of the above flags: it will not be allocated in memory, nor writable, nor
5036 executable. The section will contain data.
5038 For ELF targets, the assembler supports another type of @code{.section}
5039 directive for compatibility with the Solaris assembler:
5042 .section "@var{name}"[, @var{flags}...]
5045 Note that the section name is quoted. There may be a sequence of comma
5049 section is allocatable
5053 section is executable
5056 This directive replaces the current section and subsection. The replaced
5057 section and subsection are pushed onto the section stack. See the contents of
5058 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5059 how this directive and the other section stack directives work.
5062 @section @code{.set @var{symbol}, @var{expression}}
5064 @cindex @code{set} directive
5065 @cindex symbol value, setting
5066 Set the value of @var{symbol} to @var{expression}. This
5067 changes @var{symbol}'s value and type to conform to
5068 @var{expression}. If @var{symbol} was flagged as external, it remains
5069 flagged (@pxref{Symbol Attributes}).
5071 You may @code{.set} a symbol many times in the same assembly.
5073 If you @code{.set} a global symbol, the value stored in the object
5074 file is the last value stored into it.
5077 The syntax for @code{set} on the HPPA is
5078 @samp{@var{symbol} .set @var{expression}}.
5082 @section @code{.short @var{expressions}}
5084 @cindex @code{short} directive
5086 @code{.short} is normally the same as @samp{.word}.
5087 @xref{Word,,@code{.word}}.
5089 In some configurations, however, @code{.short} and @code{.word} generate
5090 numbers of different lengths; @pxref{Machine Dependencies}.
5094 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5097 This expects zero or more @var{expressions}, and emits
5098 a 16 bit number for each.
5103 @section @code{.single @var{flonums}}
5105 @cindex @code{single} directive
5106 @cindex floating point numbers (single)
5107 This directive assembles zero or more flonums, separated by commas. It
5108 has the same effect as @code{.float}.
5110 The exact kind of floating point numbers emitted depends on how
5111 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5115 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5116 numbers in @sc{ieee} format.
5121 @section @code{.size} (COFF version)
5123 @cindex @code{size} directive
5124 This directive is generated by compilers to include auxiliary debugging
5125 information in the symbol table. It is only permitted inside
5126 @code{.def}/@code{.endef} pairs.
5129 @samp{.size} is only meaningful when generating COFF format output; when
5130 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5134 @section @code{.size @var{name} , @var{expression}} (ELF version)
5135 @cindex @code{size} directive
5137 This directive is used to set the size associated with a symbol @var{name}.
5138 The size in bytes is computed from @var{expression} which can make use of label
5139 arithmetic. This directive is typically used to set the size of function
5143 @section @code{.sleb128 @var{expressions}}
5145 @cindex @code{sleb128} directive
5146 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5147 compact, variable length representation of numbers used by the DWARF
5148 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5150 @ifclear no-space-dir
5152 @section @code{.skip @var{size} , @var{fill}}
5154 @cindex @code{skip} directive
5155 @cindex filling memory
5156 This directive emits @var{size} bytes, each of value @var{fill}. Both
5157 @var{size} and @var{fill} are absolute expressions. If the comma and
5158 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5162 @section @code{.space @var{size} , @var{fill}}
5164 @cindex @code{space} directive
5165 @cindex filling memory
5166 This directive emits @var{size} bytes, each of value @var{fill}. Both
5167 @var{size} and @var{fill} are absolute expressions. If the comma
5168 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5173 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5174 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5175 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5176 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5185 @section @code{.space}
5186 @cindex @code{space} directive
5188 On the AMD 29K, this directive is ignored; it is accepted for
5189 compatibility with other AMD 29K assemblers.
5192 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5193 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5199 @section @code{.stabd, .stabn, .stabs}
5201 @cindex symbolic debuggers, information for
5202 @cindex @code{stab@var{x}} directives
5203 There are three directives that begin @samp{.stab}.
5204 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5205 The symbols are not entered in the @command{@value{AS}} hash table: they
5206 cannot be referenced elsewhere in the source file.
5207 Up to five fields are required:
5211 This is the symbol's name. It may contain any character except
5212 @samp{\000}, so is more general than ordinary symbol names. Some
5213 debuggers used to code arbitrarily complex structures into symbol names
5217 An absolute expression. The symbol's type is set to the low 8 bits of
5218 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5219 and debuggers choke on silly bit patterns.
5222 An absolute expression. The symbol's ``other'' attribute is set to the
5223 low 8 bits of this expression.
5226 An absolute expression. The symbol's descriptor is set to the low 16
5227 bits of this expression.
5230 An absolute expression which becomes the symbol's value.
5233 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5234 or @code{.stabs} statement, the symbol has probably already been created;
5235 you get a half-formed symbol in your object file. This is
5236 compatible with earlier assemblers!
5239 @cindex @code{stabd} directive
5240 @item .stabd @var{type} , @var{other} , @var{desc}
5242 The ``name'' of the symbol generated is not even an empty string.
5243 It is a null pointer, for compatibility. Older assemblers used a
5244 null pointer so they didn't waste space in object files with empty
5247 The symbol's value is set to the location counter,
5248 relocatably. When your program is linked, the value of this symbol
5249 is the address of the location counter when the @code{.stabd} was
5252 @cindex @code{stabn} directive
5253 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5254 The name of the symbol is set to the empty string @code{""}.
5256 @cindex @code{stabs} directive
5257 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5258 All five fields are specified.
5264 @section @code{.string} "@var{str}"
5266 @cindex string, copying to object file
5267 @cindex @code{string} directive
5269 Copy the characters in @var{str} to the object file. You may specify more than
5270 one string to copy, separated by commas. Unless otherwise specified for a
5271 particular machine, the assembler marks the end of each string with a 0 byte.
5272 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5275 @section @code{.struct @var{expression}}
5277 @cindex @code{struct} directive
5278 Switch to the absolute section, and set the section offset to @var{expression},
5279 which must be an absolute expression. You might use this as follows:
5288 This would define the symbol @code{field1} to have the value 0, the symbol
5289 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5290 value 8. Assembly would be left in the absolute section, and you would need to
5291 use a @code{.section} directive of some sort to change to some other section
5292 before further assembly.
5296 @section @code{.subsection @var{name}}
5298 @cindex @code{.subsection} directive
5299 @cindex Section Stack
5300 This is one of the ELF section stack manipulation directives. The others are
5301 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5302 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5305 This directive replaces the current subsection with @code{name}. The current
5306 section is not changed. The replaced subsection is put onto the section stack
5307 in place of the then current top of stack subsection.
5312 @section @code{.symver}
5313 @cindex @code{symver} directive
5314 @cindex symbol versioning
5315 @cindex versions of symbols
5316 Use the @code{.symver} directive to bind symbols to specific version nodes
5317 within a source file. This is only supported on ELF platforms, and is
5318 typically used when assembling files to be linked into a shared library.
5319 There are cases where it may make sense to use this in objects to be bound
5320 into an application itself so as to override a versioned symbol from a
5323 For ELF targets, the @code{.symver} directive can be used like this:
5325 .symver @var{name}, @var{name2@@nodename}
5327 If the symbol @var{name} is defined within the file
5328 being assembled, the @code{.symver} directive effectively creates a symbol
5329 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5330 just don't try and create a regular alias is that the @var{@@} character isn't
5331 permitted in symbol names. The @var{name2} part of the name is the actual name
5332 of the symbol by which it will be externally referenced. The name @var{name}
5333 itself is merely a name of convenience that is used so that it is possible to
5334 have definitions for multiple versions of a function within a single source
5335 file, and so that the compiler can unambiguously know which version of a
5336 function is being mentioned. The @var{nodename} portion of the alias should be
5337 the name of a node specified in the version script supplied to the linker when
5338 building a shared library. If you are attempting to override a versioned
5339 symbol from a shared library, then @var{nodename} should correspond to the
5340 nodename of the symbol you are trying to override.
5342 If the symbol @var{name} is not defined within the file being assembled, all
5343 references to @var{name} will be changed to @var{name2@@nodename}. If no
5344 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5347 Another usage of the @code{.symver} directive is:
5349 .symver @var{name}, @var{name2@@@@nodename}
5351 In this case, the symbol @var{name} must exist and be defined within
5352 the file being assembled. It is similar to @var{name2@@nodename}. The
5353 difference is @var{name2@@@@nodename} will also be used to resolve
5354 references to @var{name2} by the linker.
5356 The third usage of the @code{.symver} directive is:
5358 .symver @var{name}, @var{name2@@@@@@nodename}
5360 When @var{name} is not defined within the
5361 file being assembled, it is treated as @var{name2@@nodename}. When
5362 @var{name} is defined within the file being assembled, the symbol
5363 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5368 @section @code{.tag @var{structname}}
5370 @cindex COFF structure debugging
5371 @cindex structure debugging, COFF
5372 @cindex @code{tag} directive
5373 This directive is generated by compilers to include auxiliary debugging
5374 information in the symbol table. It is only permitted inside
5375 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5376 definitions in the symbol table with instances of those structures.
5379 @samp{.tag} is only used when generating COFF format output; when
5380 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5386 @section @code{.text @var{subsection}}
5388 @cindex @code{text} directive
5389 Tells @command{@value{AS}} to assemble the following statements onto the end of
5390 the text subsection numbered @var{subsection}, which is an absolute
5391 expression. If @var{subsection} is omitted, subsection number zero
5395 @section @code{.title "@var{heading}"}
5397 @cindex @code{title} directive
5398 @cindex listing control: title line
5399 Use @var{heading} as the title (second line, immediately after the
5400 source file name and pagenumber) when generating assembly listings.
5402 This directive affects subsequent pages, as well as the current page if
5403 it appears within ten lines of the top of a page.
5406 @section @code{.type @var{int}} (COFF version)
5408 @cindex COFF symbol type
5409 @cindex symbol type, COFF
5410 @cindex @code{type} directive
5411 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5412 records the integer @var{int} as the type attribute of a symbol table entry.
5415 @samp{.type} is associated only with COFF format output; when
5416 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5417 directive but ignores it.
5420 @section @code{.type @var{name} , @var{type description}} (ELF version)
5422 @cindex ELF symbol type
5423 @cindex symbol type, ELF
5424 @cindex @code{type} directive
5425 This directive is used to set the type of symbol @var{name} to be either a
5426 function symbol or an object symbol. There are five different syntaxes
5427 supported for the @var{type description} field, in order to provide
5428 compatibility with various other assemblers. The syntaxes supported are:
5431 .type <name>,#function
5432 .type <name>,#object
5434 .type <name>,@@function
5435 .type <name>,@@object
5437 .type <name>,%function
5438 .type <name>,%object
5440 .type <name>,"function"
5441 .type <name>,"object"
5443 .type <name> STT_FUNCTION
5444 .type <name> STT_OBJECT
5448 @section @code{.uleb128 @var{expressions}}
5450 @cindex @code{uleb128} directive
5451 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5452 compact, variable length representation of numbers used by the DWARF
5453 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5457 @section @code{.val @var{addr}}
5459 @cindex @code{val} directive
5460 @cindex COFF value attribute
5461 @cindex value attribute, COFF
5462 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5463 records the address @var{addr} as the value attribute of a symbol table
5467 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5468 configured for @code{b.out}, it accepts this directive but ignores it.
5474 @section @code{.version "@var{string}"}
5476 @cindex @code{.version}
5477 This directive creates a @code{.note} section and places into it an ELF
5478 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5483 @section @code{.vtable_entry @var{table}, @var{offset}}
5485 @cindex @code{.vtable_entry}
5486 This directive finds or creates a symbol @code{table} and creates a
5487 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5490 @section @code{.vtable_inherit @var{child}, @var{parent}}
5492 @cindex @code{.vtable_inherit}
5493 This directive finds the symbol @code{child} and finds or creates the symbol
5494 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5495 parent whose addend is the value of the child symbol. As a special case the
5496 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5501 @section @code{.weak @var{names}}
5503 @cindex @code{.weak}
5504 This directive sets the weak attribute on the comma separated list of symbol
5505 @code{names}. If the symbols do not already exist, they will be created.
5509 @section @code{.word @var{expressions}}
5511 @cindex @code{word} directive
5512 This directive expects zero or more @var{expressions}, of any section,
5513 separated by commas.
5516 For each expression, @command{@value{AS}} emits a 32-bit number.
5519 For each expression, @command{@value{AS}} emits a 16-bit number.
5524 The size of the number emitted, and its byte order,
5525 depend on what target computer the assembly is for.
5528 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5529 @c happen---32-bit addressability, period; no long/short jumps.
5530 @ifset DIFF-TBL-KLUGE
5531 @cindex difference tables altered
5532 @cindex altered difference tables
5534 @emph{Warning: Special Treatment to support Compilers}
5538 Machines with a 32-bit address space, but that do less than 32-bit
5539 addressing, require the following special treatment. If the machine of
5540 interest to you does 32-bit addressing (or doesn't require it;
5541 @pxref{Machine Dependencies}), you can ignore this issue.
5544 In order to assemble compiler output into something that works,
5545 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5546 Directives of the form @samp{.word sym1-sym2} are often emitted by
5547 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5548 directive of the form @samp{.word sym1-sym2}, and the difference between
5549 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5550 creates a @dfn{secondary jump table}, immediately before the next label.
5551 This secondary jump table is preceded by a short-jump to the
5552 first byte after the secondary table. This short-jump prevents the flow
5553 of control from accidentally falling into the new table. Inside the
5554 table is a long-jump to @code{sym2}. The original @samp{.word}
5555 contains @code{sym1} minus the address of the long-jump to
5558 If there were several occurrences of @samp{.word sym1-sym2} before the
5559 secondary jump table, all of them are adjusted. If there was a
5560 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5561 long-jump to @code{sym4} is included in the secondary jump table,
5562 and the @code{.word} directives are adjusted to contain @code{sym3}
5563 minus the address of the long-jump to @code{sym4}; and so on, for as many
5564 entries in the original jump table as necessary.
5567 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5568 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5569 assembly language programmers.
5572 @c end DIFF-TBL-KLUGE
5575 @section Deprecated Directives
5577 @cindex deprecated directives
5578 @cindex obsolescent directives
5579 One day these directives won't work.
5580 They are included for compatibility with older assemblers.
5587 @node Machine Dependencies
5588 @chapter Machine Dependent Features
5590 @cindex machine dependencies
5591 The machine instruction sets are (almost by definition) different on
5592 each machine where @command{@value{AS}} runs. Floating point representations
5593 vary as well, and @command{@value{AS}} often supports a few additional
5594 directives or command-line options for compatibility with other
5595 assemblers on a particular platform. Finally, some versions of
5596 @command{@value{AS}} support special pseudo-instructions for branch
5599 This chapter discusses most of these differences, though it does not
5600 include details on any machine's instruction set. For details on that
5601 subject, see the hardware manufacturer's manual.
5605 * AMD29K-Dependent:: AMD 29K Dependent Features
5608 * Alpha-Dependent:: Alpha Dependent Features
5611 * ARC-Dependent:: ARC Dependent Features
5614 * ARM-Dependent:: ARM Dependent Features
5617 * CRIS-Dependent:: CRIS Dependent Features
5620 * D10V-Dependent:: D10V Dependent Features
5623 * D30V-Dependent:: D30V Dependent Features
5626 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5629 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5632 * HPPA-Dependent:: HPPA Dependent Features
5635 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5638 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5641 * i860-Dependent:: Intel 80860 Dependent Features
5644 * i960-Dependent:: Intel 80960 Dependent Features
5647 * M32R-Dependent:: M32R Dependent Features
5650 * M68K-Dependent:: M680x0 Dependent Features
5653 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5656 * M88K-Dependent:: M880x0 Dependent Features
5659 * MIPS-Dependent:: MIPS Dependent Features
5662 * MMIX-Dependent:: MMIX Dependent Features
5665 * SH-Dependent:: Hitachi SH Dependent Features
5666 * SH64-Dependent:: Hitachi SH64 Dependent Features
5669 * PDP-11-Dependent:: PDP-11 Dependent Features
5672 * PJ-Dependent:: picoJava Dependent Features
5675 * PPC-Dependent:: PowerPC Dependent Features
5678 * Sparc-Dependent:: SPARC Dependent Features
5681 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5684 * V850-Dependent:: V850 Dependent Features
5687 * Z8000-Dependent:: Z8000 Dependent Features
5690 * Vax-Dependent:: VAX Dependent Features
5697 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5698 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5699 @c peculiarity: to preserve cross-references, there must be a node called
5700 @c "Machine Dependencies". Hence the conditional nodenames in each
5701 @c major node below. Node defaulting in makeinfo requires adjacency of
5702 @c node and sectioning commands; hence the repetition of @chapter BLAH
5703 @c in both conditional blocks.
5706 @include c-a29k.texi
5710 @include c-alpha.texi
5722 @include c-cris.texi
5727 @node Machine Dependencies
5728 @chapter Machine Dependent Features
5730 The machine instruction sets are different on each Hitachi chip family,
5731 and there are also some syntax differences among the families. This
5732 chapter describes the specific @command{@value{AS}} features for each
5736 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5737 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5738 * SH-Dependent:: Hitachi SH Dependent Features
5745 @include c-d10v.texi
5749 @include c-d30v.texi
5753 @include c-h8300.texi
5757 @include c-h8500.texi
5761 @include c-hppa.texi
5765 @include c-i370.texi
5769 @include c-i386.texi
5773 @include c-i860.texi
5777 @include c-i960.texi
5781 @include c-ia64.texi
5785 @include c-m32r.texi
5789 @include c-m68k.texi
5793 @include c-m68hc11.texi
5797 @include c-m88k.texi
5801 @include c-mips.texi
5805 @include c-mmix.texi
5809 @include c-ns32k.texi
5813 @include c-pdp11.texi
5826 @include c-sh64.texi
5830 @include c-sparc.texi
5834 @include c-tic54x.texi
5846 @include c-v850.texi
5850 @c reverse effect of @down at top of generic Machine-Dep chapter
5854 @node Reporting Bugs
5855 @chapter Reporting Bugs
5856 @cindex bugs in assembler
5857 @cindex reporting bugs in assembler
5859 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5861 Reporting a bug may help you by bringing a solution to your problem, or it may
5862 not. But in any case the principal function of a bug report is to help the
5863 entire community by making the next version of @command{@value{AS}} work better.
5864 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5866 In order for a bug report to serve its purpose, you must include the
5867 information that enables us to fix the bug.
5870 * Bug Criteria:: Have you found a bug?
5871 * Bug Reporting:: How to report bugs
5875 @section Have you found a bug?
5876 @cindex bug criteria
5878 If you are not sure whether you have found a bug, here are some guidelines:
5881 @cindex fatal signal
5882 @cindex assembler crash
5883 @cindex crash of assembler
5885 If the assembler gets a fatal signal, for any input whatever, that is a
5886 @command{@value{AS}} bug. Reliable assemblers never crash.
5888 @cindex error on valid input
5890 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5892 @cindex invalid input
5894 If @command{@value{AS}} does not produce an error message for invalid input, that
5895 is a bug. However, you should note that your idea of ``invalid input'' might
5896 be our idea of ``an extension'' or ``support for traditional practice''.
5899 If you are an experienced user of assemblers, your suggestions for improvement
5900 of @command{@value{AS}} are welcome in any case.
5904 @section How to report bugs
5906 @cindex assembler bugs, reporting
5908 A number of companies and individuals offer support for @sc{gnu} products. If
5909 you obtained @command{@value{AS}} from a support organization, we recommend you
5910 contact that organization first.
5912 You can find contact information for many support companies and
5913 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5916 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5917 to @samp{bug-binutils@@gnu.org}.
5919 The fundamental principle of reporting bugs usefully is this:
5920 @strong{report all the facts}. If you are not sure whether to state a
5921 fact or leave it out, state it!
5923 Often people omit facts because they think they know what causes the problem
5924 and assume that some details do not matter. Thus, you might assume that the
5925 name of a symbol you use in an example does not matter. Well, probably it does
5926 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5927 happens to fetch from the location where that name is stored in memory;
5928 perhaps, if the name were different, the contents of that location would fool
5929 the assembler into doing the right thing despite the bug. Play it safe and
5930 give a specific, complete example. That is the easiest thing for you to do,
5931 and the most helpful.
5933 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5934 it is new to us. Therefore, always write your bug reports on the assumption
5935 that the bug has not been reported previously.
5937 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5938 bell?'' Those bug reports are useless, and we urge everyone to
5939 @emph{refuse to respond to them} except to chide the sender to report
5942 To enable us to fix the bug, you should include all these things:
5946 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5947 it with the @samp{--version} argument.
5949 Without this, we will not know whether there is any point in looking for
5950 the bug in the current version of @command{@value{AS}}.
5953 Any patches you may have applied to the @command{@value{AS}} source.
5956 The type of machine you are using, and the operating system name and
5960 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5964 The command arguments you gave the assembler to assemble your example and
5965 observe the bug. To guarantee you will not omit something important, list them
5966 all. A copy of the Makefile (or the output from make) is sufficient.
5968 If we were to try to guess the arguments, we would probably guess wrong
5969 and then we might not encounter the bug.
5972 A complete input file that will reproduce the bug. If the bug is observed when
5973 the assembler is invoked via a compiler, send the assembler source, not the
5974 high level language source. Most compilers will produce the assembler source
5975 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5976 the options @samp{-v --save-temps}; this will save the assembler source in a
5977 file with an extension of @file{.s}, and also show you exactly how
5978 @command{@value{AS}} is being run.
5981 A description of what behavior you observe that you believe is
5982 incorrect. For example, ``It gets a fatal signal.''
5984 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5985 will certainly notice it. But if the bug is incorrect output, we might not
5986 notice unless it is glaringly wrong. You might as well not give us a chance to
5989 Even if the problem you experience is a fatal signal, you should still say so
5990 explicitly. Suppose something strange is going on, such as, your copy of
5991 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5992 library on your system. (This has happened!) Your copy might crash and ours
5993 would not. If you told us to expect a crash, then when ours fails to crash, we
5994 would know that the bug was not happening for us. If you had not told us to
5995 expect a crash, then we would not be able to draw any conclusion from our
5999 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6000 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6001 option. Always send diffs from the old file to the new file. If you even
6002 discuss something in the @command{@value{AS}} source, refer to it by context, not
6005 The line numbers in our development sources will not match those in your
6006 sources. Your line numbers would convey no useful information to us.
6009 Here are some things that are not necessary:
6013 A description of the envelope of the bug.
6015 Often people who encounter a bug spend a lot of time investigating
6016 which changes to the input file will make the bug go away and which
6017 changes will not affect it.
6019 This is often time consuming and not very useful, because the way we
6020 will find the bug is by running a single example under the debugger
6021 with breakpoints, not by pure deduction from a series of examples.
6022 We recommend that you save your time for something else.
6024 Of course, if you can find a simpler example to report @emph{instead}
6025 of the original one, that is a convenience for us. Errors in the
6026 output will be easier to spot, running under the debugger will take
6027 less time, and so on.
6029 However, simplification is not vital; if you do not want to do this,
6030 report the bug anyway and send us the entire test case you used.
6033 A patch for the bug.
6035 A patch for the bug does help us if it is a good one. But do not omit
6036 the necessary information, such as the test case, on the assumption that
6037 a patch is all we need. We might see problems with your patch and decide
6038 to fix the problem another way, or we might not understand it at all.
6040 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6041 construct an example that will make the program follow a certain path through
6042 the code. If you do not send us the example, we will not be able to construct
6043 one, so we will not be able to verify that the bug is fixed.
6045 And if we cannot understand what bug you are trying to fix, or why your
6046 patch should be an improvement, we will not install it. A test case will
6047 help us to understand.
6050 A guess about what the bug is or what it depends on.
6052 Such guesses are usually wrong. Even we cannot guess right about such
6053 things without first using the debugger to find the facts.
6056 @node Acknowledgements
6057 @chapter Acknowledgements
6059 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6060 it is not meant as a slight. We just don't know about it. Send mail to the
6061 maintainer, and we'll correct the situation. Currently
6063 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6065 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6068 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6069 information and the 68k series machines, most of the preprocessing pass, and
6070 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6072 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6073 many bug fixes, including merging support for several processors, breaking GAS
6074 up to handle multiple object file format back ends (including heavy rewrite,
6075 testing, an integration of the coff and b.out back ends), adding configuration
6076 including heavy testing and verification of cross assemblers and file splits
6077 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6078 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6079 port (including considerable amounts of reverse engineering), a SPARC opcode
6080 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6081 assertions and made them work, much other reorganization, cleanup, and lint.
6083 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6084 in format-specific I/O modules.
6086 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6087 has done much work with it since.
6089 The Intel 80386 machine description was written by Eliot Dresselhaus.
6091 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6093 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6094 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6096 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6097 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6098 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6099 support a.out format.
6101 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6102 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6103 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6104 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6107 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6108 simplified the configuration of which versions accept which directives. He
6109 updated the 68k machine description so that Motorola's opcodes always produced
6110 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6111 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6112 cross-compilation support, and one bug in relaxation that took a week and
6113 required the proverbial one-bit fix.
6115 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6116 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6117 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6118 PowerPC assembler, and made a few other minor patches.
6120 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6122 Hewlett-Packard contributed support for the HP9000/300.
6124 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6125 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6126 formats). This work was supported by both the Center for Software Science at
6127 the University of Utah and Cygnus Support.
6129 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6130 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6131 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6132 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6133 and some initial 64-bit support).
6135 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6137 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6138 support for openVMS/Alpha.
6140 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6143 Several engineers at Cygnus Support have also provided many small bug fixes and
6144 configuration enhancements.
6146 Many others have contributed large or small bugfixes and enhancements. If
6147 you have contributed significant work and are not mentioned on this list, and
6148 want to be, let us know. Some of the history has been lost; we are not
6149 intentionally leaving anyone out.
6151 @node GNU Free Documentation License
6152 @chapter GNU Free Documentation License
6154 GNU Free Documentation License
6156 Version 1.1, March 2000
6158 Copyright (C) 2000 Free Software Foundation, Inc.
6159 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6161 Everyone is permitted to copy and distribute verbatim copies
6162 of this license document, but changing it is not allowed.
6167 The purpose of this License is to make a manual, textbook, or other
6168 written document "free" in the sense of freedom: to assure everyone
6169 the effective freedom to copy and redistribute it, with or without
6170 modifying it, either commercially or noncommercially. Secondarily,
6171 this License preserves for the author and publisher a way to get
6172 credit for their work, while not being considered responsible for
6173 modifications made by others.
6175 This License is a kind of "copyleft", which means that derivative
6176 works of the document must themselves be free in the same sense. It
6177 complements the GNU General Public License, which is a copyleft
6178 license designed for free software.
6180 We have designed this License in order to use it for manuals for free
6181 software, because free software needs free documentation: a free
6182 program should come with manuals providing the same freedoms that the
6183 software does. But this License is not limited to software manuals;
6184 it can be used for any textual work, regardless of subject matter or
6185 whether it is published as a printed book. We recommend this License
6186 principally for works whose purpose is instruction or reference.
6189 1. APPLICABILITY AND DEFINITIONS
6191 This License applies to any manual or other work that contains a
6192 notice placed by the copyright holder saying it can be distributed
6193 under the terms of this License. The "Document", below, refers to any
6194 such manual or work. Any member of the public is a licensee, and is
6197 A "Modified Version" of the Document means any work containing the
6198 Document or a portion of it, either copied verbatim, or with
6199 modifications and/or translated into another language.
6201 A "Secondary Section" is a named appendix or a front-matter section of
6202 the Document that deals exclusively with the relationship of the
6203 publishers or authors of the Document to the Document's overall subject
6204 (or to related matters) and contains nothing that could fall directly
6205 within that overall subject. (For example, if the Document is in part a
6206 textbook of mathematics, a Secondary Section may not explain any
6207 mathematics.) The relationship could be a matter of historical
6208 connection with the subject or with related matters, or of legal,
6209 commercial, philosophical, ethical or political position regarding
6212 The "Invariant Sections" are certain Secondary Sections whose titles
6213 are designated, as being those of Invariant Sections, in the notice
6214 that says that the Document is released under this License.
6216 The "Cover Texts" are certain short passages of text that are listed,
6217 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6218 the Document is released under this License.
6220 A "Transparent" copy of the Document means a machine-readable copy,
6221 represented in a format whose specification is available to the
6222 general public, whose contents can be viewed and edited directly and
6223 straightforwardly with generic text editors or (for images composed of
6224 pixels) generic paint programs or (for drawings) some widely available
6225 drawing editor, and that is suitable for input to text formatters or
6226 for automatic translation to a variety of formats suitable for input
6227 to text formatters. A copy made in an otherwise Transparent file
6228 format whose markup has been designed to thwart or discourage
6229 subsequent modification by readers is not Transparent. A copy that is
6230 not "Transparent" is called "Opaque".
6232 Examples of suitable formats for Transparent copies include plain
6233 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6234 or XML using a publicly available DTD, and standard-conforming simple
6235 HTML designed for human modification. Opaque formats include
6236 PostScript, PDF, proprietary formats that can be read and edited only
6237 by proprietary word processors, SGML or XML for which the DTD and/or
6238 processing tools are not generally available, and the
6239 machine-generated HTML produced by some word processors for output
6242 The "Title Page" means, for a printed book, the title page itself,
6243 plus such following pages as are needed to hold, legibly, the material
6244 this License requires to appear in the title page. For works in
6245 formats which do not have any title page as such, "Title Page" means
6246 the text near the most prominent appearance of the work's title,
6247 preceding the beginning of the body of the text.
6252 You may copy and distribute the Document in any medium, either
6253 commercially or noncommercially, provided that this License, the
6254 copyright notices, and the license notice saying this License applies
6255 to the Document are reproduced in all copies, and that you add no other
6256 conditions whatsoever to those of this License. You may not use
6257 technical measures to obstruct or control the reading or further
6258 copying of the copies you make or distribute. However, you may accept
6259 compensation in exchange for copies. If you distribute a large enough
6260 number of copies you must also follow the conditions in section 3.
6262 You may also lend copies, under the same conditions stated above, and
6263 you may publicly display copies.
6266 3. COPYING IN QUANTITY
6268 If you publish printed copies of the Document numbering more than 100,
6269 and the Document's license notice requires Cover Texts, you must enclose
6270 the copies in covers that carry, clearly and legibly, all these Cover
6271 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6272 the back cover. Both covers must also clearly and legibly identify
6273 you as the publisher of these copies. The front cover must present
6274 the full title with all words of the title equally prominent and
6275 visible. You may add other material on the covers in addition.
6276 Copying with changes limited to the covers, as long as they preserve
6277 the title of the Document and satisfy these conditions, can be treated
6278 as verbatim copying in other respects.
6280 If the required texts for either cover are too voluminous to fit
6281 legibly, you should put the first ones listed (as many as fit
6282 reasonably) on the actual cover, and continue the rest onto adjacent
6285 If you publish or distribute Opaque copies of the Document numbering
6286 more than 100, you must either include a machine-readable Transparent
6287 copy along with each Opaque copy, or state in or with each Opaque copy
6288 a publicly-accessible computer-network location containing a complete
6289 Transparent copy of the Document, free of added material, which the
6290 general network-using public has access to download anonymously at no
6291 charge using public-standard network protocols. If you use the latter
6292 option, you must take reasonably prudent steps, when you begin
6293 distribution of Opaque copies in quantity, to ensure that this
6294 Transparent copy will remain thus accessible at the stated location
6295 until at least one year after the last time you distribute an Opaque
6296 copy (directly or through your agents or retailers) of that edition to
6299 It is requested, but not required, that you contact the authors of the
6300 Document well before redistributing any large number of copies, to give
6301 them a chance to provide you with an updated version of the Document.
6306 You may copy and distribute a Modified Version of the Document under
6307 the conditions of sections 2 and 3 above, provided that you release
6308 the Modified Version under precisely this License, with the Modified
6309 Version filling the role of the Document, thus licensing distribution
6310 and modification of the Modified Version to whoever possesses a copy
6311 of it. In addition, you must do these things in the Modified Version:
6313 A. Use in the Title Page (and on the covers, if any) a title distinct
6314 from that of the Document, and from those of previous versions
6315 (which should, if there were any, be listed in the History section
6316 of the Document). You may use the same title as a previous version
6317 if the original publisher of that version gives permission.
6318 B. List on the Title Page, as authors, one or more persons or entities
6319 responsible for authorship of the modifications in the Modified
6320 Version, together with at least five of the principal authors of the
6321 Document (all of its principal authors, if it has less than five).
6322 C. State on the Title page the name of the publisher of the
6323 Modified Version, as the publisher.
6324 D. Preserve all the copyright notices of the Document.
6325 E. Add an appropriate copyright notice for your modifications
6326 adjacent to the other copyright notices.
6327 F. Include, immediately after the copyright notices, a license notice
6328 giving the public permission to use the Modified Version under the
6329 terms of this License, in the form shown in the Addendum below.
6330 G. Preserve in that license notice the full lists of Invariant Sections
6331 and required Cover Texts given in the Document's license notice.
6332 H. Include an unaltered copy of this License.
6333 I. Preserve the section entitled "History", and its title, and add to
6334 it an item stating at least the title, year, new authors, and
6335 publisher of the Modified Version as given on the Title Page. If
6336 there is no section entitled "History" in the Document, create one
6337 stating the title, year, authors, and publisher of the Document as
6338 given on its Title Page, then add an item describing the Modified
6339 Version as stated in the previous sentence.
6340 J. Preserve the network location, if any, given in the Document for
6341 public access to a Transparent copy of the Document, and likewise
6342 the network locations given in the Document for previous versions
6343 it was based on. These may be placed in the "History" section.
6344 You may omit a network location for a work that was published at
6345 least four years before the Document itself, or if the original
6346 publisher of the version it refers to gives permission.
6347 K. In any section entitled "Acknowledgements" or "Dedications",
6348 preserve the section's title, and preserve in the section all the
6349 substance and tone of each of the contributor acknowledgements
6350 and/or dedications given therein.
6351 L. Preserve all the Invariant Sections of the Document,
6352 unaltered in their text and in their titles. Section numbers
6353 or the equivalent are not considered part of the section titles.
6354 M. Delete any section entitled "Endorsements". Such a section
6355 may not be included in the Modified Version.
6356 N. Do not retitle any existing section as "Endorsements"
6357 or to conflict in title with any Invariant Section.
6359 If the Modified Version includes new front-matter sections or
6360 appendices that qualify as Secondary Sections and contain no material
6361 copied from the Document, you may at your option designate some or all
6362 of these sections as invariant. To do this, add their titles to the
6363 list of Invariant Sections in the Modified Version's license notice.
6364 These titles must be distinct from any other section titles.
6366 You may add a section entitled "Endorsements", provided it contains
6367 nothing but endorsements of your Modified Version by various
6368 parties--for example, statements of peer review or that the text has
6369 been approved by an organization as the authoritative definition of a
6372 You may add a passage of up to five words as a Front-Cover Text, and a
6373 passage of up to 25 words as a Back-Cover Text, to the end of the list
6374 of Cover Texts in the Modified Version. Only one passage of
6375 Front-Cover Text and one of Back-Cover Text may be added by (or
6376 through arrangements made by) any one entity. If the Document already
6377 includes a cover text for the same cover, previously added by you or
6378 by arrangement made by the same entity you are acting on behalf of,
6379 you may not add another; but you may replace the old one, on explicit
6380 permission from the previous publisher that added the old one.
6382 The author(s) and publisher(s) of the Document do not by this License
6383 give permission to use their names for publicity for or to assert or
6384 imply endorsement of any Modified Version.
6387 5. COMBINING DOCUMENTS
6389 You may combine the Document with other documents released under this
6390 License, under the terms defined in section 4 above for modified
6391 versions, provided that you include in the combination all of the
6392 Invariant Sections of all of the original documents, unmodified, and
6393 list them all as Invariant Sections of your combined work in its
6396 The combined work need only contain one copy of this License, and
6397 multiple identical Invariant Sections may be replaced with a single
6398 copy. If there are multiple Invariant Sections with the same name but
6399 different contents, make the title of each such section unique by
6400 adding at the end of it, in parentheses, the name of the original
6401 author or publisher of that section if known, or else a unique number.
6402 Make the same adjustment to the section titles in the list of
6403 Invariant Sections in the license notice of the combined work.
6405 In the combination, you must combine any sections entitled "History"
6406 in the various original documents, forming one section entitled
6407 "History"; likewise combine any sections entitled "Acknowledgements",
6408 and any sections entitled "Dedications". You must delete all sections
6409 entitled "Endorsements."
6412 6. COLLECTIONS OF DOCUMENTS
6414 You may make a collection consisting of the Document and other documents
6415 released under this License, and replace the individual copies of this
6416 License in the various documents with a single copy that is included in
6417 the collection, provided that you follow the rules of this License for
6418 verbatim copying of each of the documents in all other respects.
6420 You may extract a single document from such a collection, and distribute
6421 it individually under this License, provided you insert a copy of this
6422 License into the extracted document, and follow this License in all
6423 other respects regarding verbatim copying of that document.
6426 7. AGGREGATION WITH INDEPENDENT WORKS
6428 A compilation of the Document or its derivatives with other separate
6429 and independent documents or works, in or on a volume of a storage or
6430 distribution medium, does not as a whole count as a Modified Version
6431 of the Document, provided no compilation copyright is claimed for the
6432 compilation. Such a compilation is called an "aggregate", and this
6433 License does not apply to the other self-contained works thus compiled
6434 with the Document, on account of their being thus compiled, if they
6435 are not themselves derivative works of the Document.
6437 If the Cover Text requirement of section 3 is applicable to these
6438 copies of the Document, then if the Document is less than one quarter
6439 of the entire aggregate, the Document's Cover Texts may be placed on
6440 covers that surround only the Document within the aggregate.
6441 Otherwise they must appear on covers around the whole aggregate.
6446 Translation is considered a kind of modification, so you may
6447 distribute translations of the Document under the terms of section 4.
6448 Replacing Invariant Sections with translations requires special
6449 permission from their copyright holders, but you may include
6450 translations of some or all Invariant Sections in addition to the
6451 original versions of these Invariant Sections. You may include a
6452 translation of this License provided that you also include the
6453 original English version of this License. In case of a disagreement
6454 between the translation and the original English version of this
6455 License, the original English version will prevail.
6460 You may not copy, modify, sublicense, or distribute the Document except
6461 as expressly provided for under this License. Any other attempt to
6462 copy, modify, sublicense or distribute the Document is void, and will
6463 automatically terminate your rights under this License. However,
6464 parties who have received copies, or rights, from you under this
6465 License will not have their licenses terminated so long as such
6466 parties remain in full compliance.
6469 10. FUTURE REVISIONS OF THIS LICENSE
6471 The Free Software Foundation may publish new, revised versions
6472 of the GNU Free Documentation License from time to time. Such new
6473 versions will be similar in spirit to the present version, but may
6474 differ in detail to address new problems or concerns. See
6475 http://www.gnu.org/copyleft/.
6477 Each version of the License is given a distinguishing version number.
6478 If the Document specifies that a particular numbered version of this
6479 License "or any later version" applies to it, you have the option of
6480 following the terms and conditions either of that specified version or
6481 of any later version that has been published (not as a draft) by the
6482 Free Software Foundation. If the Document does not specify a version
6483 number of this License, you may choose any version ever published (not
6484 as a draft) by the Free Software Foundation.
6487 ADDENDUM: How to use this License for your documents
6489 To use this License in a document you have written, include a copy of
6490 the License in the document and put the following copyright and
6491 license notices just after the title page:
6494 Copyright (c) YEAR YOUR NAME.
6495 Permission is granted to copy, distribute and/or modify this document
6496 under the terms of the GNU Free Documentation License, Version 1.1
6497 or any later version published by the Free Software Foundation;
6498 with the Invariant Sections being LIST THEIR TITLES, with the
6499 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6500 A copy of the license is included in the section entitled "GNU
6501 Free Documentation License".
6504 If you have no Invariant Sections, write "with no Invariant Sections"
6505 instead of saying which ones are invariant. If you have no
6506 Front-Cover Texts, write "no Front-Cover Texts" instead of
6507 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6509 If your document contains nontrivial examples of program code, we
6510 recommend releasing these examples in parallel under your choice of
6511 free software license, such as the GNU General Public License,
6512 to permit their use in free software.
projects / external / binutils.git / blob