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
62 @c common OR combinations of conditions
82 @set abnormal-separator
86 @settitle Using @value{AS}
89 @settitle Using @value{AS} (@value{TARGET})
91 @setchapternewpage odd
96 @c WARE! Some of the machine-dependent sections contain tables of machine
97 @c instructions. Except in multi-column format, these tables look silly.
98 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
99 @c the multi-col format is faked within @example sections.
101 @c Again unfortunately, the natural size that fits on a page, for these tables,
102 @c is different depending on whether or not smallbook is turned on.
103 @c This matters, because of order: text flow switches columns at each page
106 @c The format faked in this source works reasonably well for smallbook,
107 @c not well for the default large-page format. This manual expects that if you
108 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
109 @c tables in question. You can turn on one without the other at your
110 @c discretion, of course.
113 @c the insn tables look just as silly in info files regardless of smallbook,
114 @c might as well show 'em anyways.
120 * As: (as). The GNU assembler.
129 This file documents the GNU Assembler "@value{AS}".
131 @c man begin COPYRIGHT
132 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
134 Permission is granted to copy, distribute and/or modify this document
135 under the terms of the GNU Free Documentation License, Version 1.1
136 or any later version published by the Free Software Foundation;
137 with no Invariant Sections, with no Front-Cover Texts, and with no
138 Back-Cover Texts. A copy of the license is included in the
139 section entitled "GNU Free Documentation License".
144 Permission is granted to process this file through Tex and print the
145 results, provided the printed document carries copying permission
146 notice identical to this one except for the removal of this paragraph
147 (this paragraph not being relevant to the printed manual).
153 @title Using @value{AS}
154 @subtitle The @sc{gnu} Assembler
156 @subtitle for the @value{TARGET} family
159 @subtitle Version @value{VERSION}
162 The Free Software Foundation Inc. thanks The Nice Computer
163 Company of Australia for loaning Dean Elsner to write the
164 first (Vax) version of @command{as} for Project @sc{gnu}.
165 The proprietors, management and staff of TNCCA thank FSF for
166 distracting the boss while they got some work
169 @author Dean Elsner, Jay Fenlason & friends
173 \hfill {\it Using {\tt @value{AS}}}\par
174 \hfill Edited by Cygnus Support\par
176 %"boxit" macro for figures:
177 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
178 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
179 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
180 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
181 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
184 @vskip 0pt plus 1filll
185 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
187 Permission is granted to copy, distribute and/or modify this document
188 under the terms of the GNU Free Documentation License, Version 1.1
189 or any later version published by the Free Software Foundation;
190 with no Invariant Sections, with no Front-Cover Texts, and with no
191 Back-Cover Texts. A copy of the license is included in the
192 section entitled "GNU Free Documentation License".
198 @top Using @value{AS}
200 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
203 This version of the file describes @command{@value{AS}} configured to generate
204 code for @value{TARGET} architectures.
207 This document is distributed under the terms of the GNU Free
208 Documentation License. A copy of the license is included in the
209 section entitled "GNU Free Documentation License".
212 * Overview:: Overview
213 * Invoking:: Command-Line Options
215 * Sections:: Sections and Relocation
217 * Expressions:: Expressions
218 * Pseudo Ops:: Assembler Directives
219 * Machine Dependencies:: Machine Dependent Features
220 * Reporting Bugs:: Reporting Bugs
221 * Acknowledgements:: Who Did What
222 * GNU Free Documentation License:: GNU Free Documentation License
230 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
232 This version of the manual describes @command{@value{AS}} configured to generate
233 code for @value{TARGET} architectures.
237 @cindex invocation summary
238 @cindex option summary
239 @cindex summary of options
240 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
241 @pxref{Invoking,,Comand-Line Options}.
243 @c man title AS the portable GNU assembler.
247 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
251 @c We don't use deffn and friends for the following because they seem
252 @c to be limited to one line for the header.
254 @c man begin SYNOPSIS
255 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
256 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
257 [@b{-J}] [@b{-K}] [@b{-L}]
258 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
259 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
260 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
261 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
262 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
263 [@b{--}|@var{files} @dots{}]
265 @c Target dependent options are listed below. Keep the list sorted.
266 @c Add an empty line for separation.
268 @c am29k has no machine-dependent assembler options
272 @emph{Target Alpha options:}
274 [@b{-mdebug} | @b{-no-mdebug}]
275 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
276 [@b{-F}] [@b{-32addr}]
280 @emph{Target ARC options:}
286 @emph{Target ARM options:}
287 @c Don't document the deprecated options
288 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
289 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
290 [@b{-mfpu}=@var{floating-point-fromat}]
293 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
294 @b{-mapcs-reentrant}]
295 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
299 @emph{Target CRIS options:}
300 [@b{--underscore} | @b{--no-underscore}]
302 [@b{--emulation=criself} | @b{--emulation=crisaout}]
303 @c Deprecated -- deliberately not documented.
308 @emph{Target D10V options:}
313 @emph{Target D30V options:}
314 [@b{-O}|@b{-n}|@b{-N}]
317 @c Hitachi family chips have no machine-dependent assembler options
320 @c HPPA has no machine-dependent assembler options (yet).
324 @emph{Target i386 options:}
329 @emph{Target i960 options:}
330 @c see md_parse_option in tc-i960.c
331 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
333 [@b{-b}] [@b{-no-relax}]
337 @emph{Target M32R options:}
338 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
343 @emph{Target M680X0 options:}
344 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
348 @emph{Target M68HC11 options:}
349 [@b{-m68hc11}|@b{-m68hc12}]
350 [@b{--force-long-branchs}] [@b{--short-branchs}]
351 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
352 [@b{--print-opcodes}] [@b{--generate-example}]
356 @emph{Target MCORE options:}
357 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
358 [@b{-mcpu=[210|340]}]
362 @emph{Target MIPS options:}
363 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
364 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
365 [@b{-mips32}] [@b{-mips64}]
366 [@b{-m4650}] [@b{-no-m4650}]
367 [@b{--trap}] [@b{--break}] [@b{-n}]
368 [@b{--emulation}=@var{name} ]
372 @emph{Target MMIX options:}
373 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
374 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
375 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
376 [@b{--linker-allocated-gregs}]
380 @emph{Target PDP11 options:}
381 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
382 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
383 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
387 @emph{Target picoJava options:}
392 @emph{Target PowerPC options:}
393 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
394 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
395 @b{-mbooke32}|@b{-mbooke64}]
396 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
397 [@b{-mregnames}|@b{-mno-regnames}]
398 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
399 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
400 [@b{-msolaris}|@b{-mno-solaris}]
404 @emph{Target SPARC options:}
405 @c The order here is important. See c-sparc.texi.
406 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
407 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
408 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
413 @emph{Target TIC54X options:}
414 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
415 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
418 @c Z8000 has no machine-dependent assembler options
427 Turn on listings, in any of a variety of ways:
431 omit false conditionals
434 omit debugging directives
437 include high-level source
443 include macro expansions
446 omit forms processing
452 set the name of the listing file
455 You may combine these options; for example, use @samp{-aln} for assembly
456 listing without forms processing. The @samp{=file} option, if used, must be
457 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
460 Ignored. This option is accepted for script compatibility with calls to
463 @item --defsym @var{sym}=@var{value}
464 Define the symbol @var{sym} to be @var{value} before assembling the input file.
465 @var{value} must be an integer constant. As in C, a leading @samp{0x}
466 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
469 ``fast''---skip whitespace and comment preprocessing (assume source is
473 Generate stabs debugging information for each assembler line. This
474 may help debugging assembler code, if the debugger can handle it.
477 Generate DWARF2 debugging information for each assembler line. This
478 may help debugging assembler code, if the debugger can handle it. Note - this
479 option is only supported by some targets, not all of them.
482 Print a summary of the command line options and exit.
485 Print a summary of all target specific options and exit.
488 Add directory @var{dir} to the search list for @code{.include} directives.
491 Don't warn about signed overflow.
494 @ifclear DIFF-TBL-KLUGE
495 This option is accepted but has no effect on the @value{TARGET} family.
497 @ifset DIFF-TBL-KLUGE
498 Issue warnings when difference tables altered for long displacements.
503 Keep (in the symbol table) local symbols. On traditional a.out systems
504 these start with @samp{L}, but different systems have different local
507 @item --listing-lhs-width=@var{number}
508 Set the maximum width, in words, of the output data column for an assembler
509 listing to @var{number}.
511 @item --listing-lhs-width2=@var{number}
512 Set the maximum width, in words, of the output data column for continuation
513 lines in an assembler listing to @var{number}.
515 @item --listing-rhs-width=@var{number}
516 Set the maximum width of an input source line, as displayed in a listing, to
519 @item --listing-cont-lines=@var{number}
520 Set the maximum number of lines printed in a listing for a single line of input
523 @item -o @var{objfile}
524 Name the object-file output from @command{@value{AS}} @var{objfile}.
527 Fold the data section into the text section.
530 Print the maximum space (in bytes) and total time (in seconds) used by
533 @item --strip-local-absolute
534 Remove local absolute symbols from the outgoing symbol table.
538 Print the @command{as} version.
541 Print the @command{as} version and exit.
545 Suppress warning messages.
547 @item --fatal-warnings
548 Treat warnings as errors.
551 Don't suppress warning messages or treat them as errors.
560 Generate an object file even after errors.
562 @item -- | @var{files} @dots{}
563 Standard input, or source files to assemble.
568 The following options are available when @value{AS} is configured for
573 This option selects the core processor variant.
575 Select either big-endian (-EB) or little-endian (-EL) output.
580 The following options are available when @value{AS} is configured for the ARM
584 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
585 Specify which ARM processor variant is the target.
586 @item -march=@var{architecture}[+@var{extension}@dots{}]
587 Specify which ARM architecture variant is used by the target.
588 @item -mfpu=@var{floating-point-format}
589 Select which Floating Point architecture is the target.
591 Enable Thumb only instruction decoding.
592 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
593 Select which procedure calling convention is in use.
595 Select either big-endian (-EB) or little-endian (-EL) output.
596 @item -mthumb-interwork
597 Specify that the code has been generated with interworking between Thumb and
600 Specify that PIC code has been generated.
605 See the info pages for documentation of the CRIS-specific options.
609 The following options are available when @value{AS} is configured for
612 @cindex D10V optimization
613 @cindex optimization, D10V
615 Optimize output by parallelizing instructions.
620 The following options are available when @value{AS} is configured for a D30V
623 @cindex D30V optimization
624 @cindex optimization, D30V
626 Optimize output by parallelizing instructions.
630 Warn when nops are generated.
632 @cindex D30V nops after 32-bit multiply
634 Warn when a nop after a 32-bit multiply instruction is generated.
639 The following options are available when @value{AS} is configured for the
640 Intel 80960 processor.
643 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
644 Specify which variant of the 960 architecture is the target.
647 Add code to collect statistics about branches taken.
650 Do not alter compare-and-branch instructions for long displacements;
657 The following options are available when @value{AS} is configured for the
658 Mitsubishi M32R series.
663 Specify which processor in the M32R family is the target. The default
664 is normally the M32R, but this option changes it to the M32RX.
666 @item --warn-explicit-parallel-conflicts or --Wp
667 Produce warning messages when questionable parallel constructs are
670 @item --no-warn-explicit-parallel-conflicts or --Wnp
671 Do not produce warning messages when questionable parallel constructs are
678 The following options are available when @value{AS} is configured for the
679 Motorola 68000 series.
684 Shorten references to undefined symbols, to one word instead of two.
686 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
687 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
688 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
689 Specify what processor in the 68000 family is the target. The default
690 is normally the 68020, but this can be changed at configuration time.
692 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
693 The target machine does (or does not) have a floating-point coprocessor.
694 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
695 the basic 68000 is not compatible with the 68881, a combination of the
696 two can be specified, since it's possible to do emulation of the
697 coprocessor instructions with the main processor.
699 @item -m68851 | -mno-68851
700 The target machine does (or does not) have a memory-management
701 unit coprocessor. The default is to assume an MMU for 68020 and up.
708 For details about the PDP-11 machine dependent features options,
709 see @ref{PDP-11-Options}.
712 @item -mpic | -mno-pic
713 Generate position-independent (or position-dependent) code. The
714 default is @option{-mpic}.
717 @itemx -mall-extensions
718 Enable all instruction set extensions. This is the default.
720 @item -mno-extensions
721 Disable all instruction set extensions.
723 @item -m@var{extension} | -mno-@var{extension}
724 Enable (or disable) a particular instruction set extension.
727 Enable the instruction set extensions supported by a particular CPU, and
728 disable all other extensions.
730 @item -m@var{machine}
731 Enable the instruction set extensions supported by a particular machine
732 model, and disable all other extensions.
738 The following options are available when @value{AS} is configured for
739 a picoJava processor.
743 @cindex PJ endianness
744 @cindex endianness, PJ
745 @cindex big endian output, PJ
747 Generate ``big endian'' format output.
749 @cindex little endian output, PJ
751 Generate ``little endian'' format output.
757 The following options are available when @value{AS} is configured for the
758 Motorola 68HC11 or 68HC12 series.
762 @item -m68hc11 | -m68hc12
763 Specify what processor is the target. The default is
764 defined by the configuration option when building the assembler.
766 @item --force-long-branchs
767 Relative branches are turned into absolute ones. This concerns
768 conditional branches, unconditional branches and branches to a
771 @item -S | --short-branchs
772 Do not turn relative branchs into absolute ones
773 when the offset is out of range.
775 @item --strict-direct-mode
776 Do not turn the direct addressing mode into extended addressing mode
777 when the instruction does not support direct addressing mode.
779 @item --print-insn-syntax
780 Print the syntax of instruction in case of error.
782 @item --print-opcodes
783 print the list of instructions with syntax and then exit.
785 @item --generate-example
786 print an example of instruction for each possible instruction and then exit.
787 This option is only useful for testing @command{@value{AS}}.
793 The following options are available when @command{@value{AS}} is configured
794 for the SPARC architecture:
797 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
798 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
799 Explicitly select a variant of the SPARC architecture.
801 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
802 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
804 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
805 UltraSPARC extensions.
807 @item -xarch=v8plus | -xarch=v8plusa
808 For compatibility with the Solaris v9 assembler. These options are
809 equivalent to -Av8plus and -Av8plusa, respectively.
812 Warn when the assembler switches to another architecture.
817 The following options are available when @value{AS} is configured for the 'c54x
822 Enable extended addressing mode. All addresses and relocations will assume
823 extended addressing (usually 23 bits).
824 @item -mcpu=@var{CPU_VERSION}
825 Sets the CPU version being compiled for.
826 @item -merrors-to-file @var{FILENAME}
827 Redirect error output to a file, for broken systems which don't support such
828 behaviour in the shell.
833 The following options are available when @value{AS} is configured for
838 This option sets the largest size of an object that can be referenced
839 implicitly with the @code{gp} register. It is only accepted for targets that
840 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
842 @cindex MIPS endianness
843 @cindex endianness, MIPS
844 @cindex big endian output, MIPS
846 Generate ``big endian'' format output.
848 @cindex little endian output, MIPS
850 Generate ``little endian'' format output.
859 Generate code for a particular MIPS Instruction Set Architecture level.
860 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
861 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
863 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
864 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
865 processors, respectively.
869 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
870 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
871 instructions around accesses to the @samp{HI} and @samp{LO} registers.
872 @samp{-no-m4650} turns off this option.
874 @item -mcpu=@var{CPU}
875 Generate code for a particular MIPS cpu. It is exactly equivalent to
876 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
880 @item --emulation=@var{name}
881 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
882 for some other target, in all respects, including output format (choosing
883 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
884 debugging information or store symbol table information, and default
885 endianness. The available configuration names are: @samp{mipsecoff},
886 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
887 @samp{mipsbelf}. The first two do not alter the default endianness from that
888 of the primary target for which the assembler was configured; the others change
889 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
890 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
891 selection in any case.
893 This option is currently supported only when the primary target
894 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
895 Furthermore, the primary target or others specified with
896 @samp{--enable-targets=@dots{}} at configuration time must include support for
897 the other format, if both are to be available. For example, the Irix 5
898 configuration includes support for both.
900 Eventually, this option will support more configurations, with more
901 fine-grained control over the assembler's behavior, and will be supported for
905 @command{@value{AS}} ignores this option. It is accepted for compatibility with
913 Control how to deal with multiplication overflow and division by zero.
914 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
915 (and only work for Instruction Set Architecture level 2 and higher);
916 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
920 When this option is used, @command{@value{AS}} will issue a warning every
921 time it generates a nop instruction from a macro.
926 The following options are available when @value{AS} is configured for
932 Enable or disable the JSRI to BSR transformation. By default this is enabled.
933 The command line option @samp{-nojsri2bsr} can be used to disable it.
937 Enable or disable the silicon filter behaviour. By default this is disabled.
938 The default can be overridden by the @samp{-sifilter} command line option.
941 Alter jump instructions for long displacements.
943 @item -mcpu=[210|340]
944 Select the cpu type on the target hardware. This controls which instructions
948 Assemble for a big endian target.
951 Assemble for a little endian target.
957 See the info pages for documentation of the MMIX-specific options.
963 * Manual:: Structure of this Manual
964 * GNU Assembler:: The GNU Assembler
965 * Object Formats:: Object File Formats
966 * Command Line:: Command Line
967 * Input Files:: Input Files
968 * Object:: Output (Object) File
969 * Errors:: Error and Warning Messages
973 @section Structure of this Manual
975 @cindex manual, structure and purpose
976 This manual is intended to describe what you need to know to use
977 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
978 notation for symbols, constants, and expressions; the directives that
979 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
982 We also cover special features in the @value{TARGET}
983 configuration of @command{@value{AS}}, including assembler directives.
986 This manual also describes some of the machine-dependent features of
987 various flavors of the assembler.
990 @cindex machine instructions (not covered)
991 On the other hand, this manual is @emph{not} intended as an introduction
992 to programming in assembly language---let alone programming in general!
993 In a similar vein, we make no attempt to introduce the machine
994 architecture; we do @emph{not} describe the instruction set, standard
995 mnemonics, registers or addressing modes that are standard to a
996 particular architecture.
998 You may want to consult the manufacturer's
999 machine architecture manual for this information.
1003 For information on the H8/300 machine instruction set, see @cite{H8/300
1004 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1005 see @cite{H8/300H Series Programming Manual} (Hitachi).
1008 For information on the H8/500 machine instruction set, see @cite{H8/500
1009 Series Programming Manual} (Hitachi M21T001).
1012 For information on the Hitachi SH machine instruction set, see
1013 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1016 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1020 @c I think this is premature---doc@cygnus.com, 17jan1991
1022 Throughout this manual, we assume that you are running @dfn{GNU},
1023 the portable operating system from the @dfn{Free Software
1024 Foundation, Inc.}. This restricts our attention to certain kinds of
1025 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1026 once this assumption is granted examples and definitions need less
1029 @command{@value{AS}} is part of a team of programs that turn a high-level
1030 human-readable series of instructions into a low-level
1031 computer-readable series of instructions. Different versions of
1032 @command{@value{AS}} are used for different kinds of computer.
1035 @c There used to be a section "Terminology" here, which defined
1036 @c "contents", "byte", "word", and "long". Defining "word" to any
1037 @c particular size is confusing when the .word directive may generate 16
1038 @c bits on one machine and 32 bits on another; in general, for the user
1039 @c version of this manual, none of these terms seem essential to define.
1040 @c They were used very little even in the former draft of the manual;
1041 @c this draft makes an effort to avoid them (except in names of
1045 @section The GNU Assembler
1047 @c man begin DESCRIPTION
1049 @sc{gnu} @command{as} is really a family of assemblers.
1051 This manual describes @command{@value{AS}}, a member of that family which is
1052 configured for the @value{TARGET} architectures.
1054 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1055 should find a fairly similar environment when you use it on another
1056 architecture. Each version has much in common with the others,
1057 including object file formats, most assembler directives (often called
1058 @dfn{pseudo-ops}) and assembler syntax.@refill
1060 @cindex purpose of @sc{gnu} assembler
1061 @command{@value{AS}} is primarily intended to assemble the output of the
1062 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1063 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1064 assemble correctly everything that other assemblers for the same
1065 machine would assemble.
1067 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1070 @c This remark should appear in generic version of manual; assumption
1071 @c here is that generic version sets M680x0.
1072 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1073 assembler for the same architecture; for example, we know of several
1074 incompatible versions of 680x0 assembly language syntax.
1079 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1080 program in one pass of the source file. This has a subtle impact on the
1081 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1083 @node Object Formats
1084 @section Object File Formats
1086 @cindex object file format
1087 The @sc{gnu} assembler can be configured to produce several alternative
1088 object file formats. For the most part, this does not affect how you
1089 write assembly language programs; but directives for debugging symbols
1090 are typically different in different file formats. @xref{Symbol
1091 Attributes,,Symbol Attributes}.
1094 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1095 @value{OBJ-NAME} format object files.
1097 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1099 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1100 @code{a.out} or COFF format object files.
1103 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1104 @code{b.out} or COFF format object files.
1107 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1108 SOM or ELF format object files.
1113 @section Command Line
1115 @cindex command line conventions
1117 After the program name @command{@value{AS}}, the command line may contain
1118 options and file names. Options may appear in any order, and may be
1119 before, after, or between file names. The order of file names is
1122 @cindex standard input, as input file
1124 @file{--} (two hyphens) by itself names the standard input file
1125 explicitly, as one of the files for @command{@value{AS}} to assemble.
1127 @cindex options, command line
1128 Except for @samp{--} any command line argument that begins with a
1129 hyphen (@samp{-}) is an option. Each option changes the behavior of
1130 @command{@value{AS}}. No option changes the way another option works. An
1131 option is a @samp{-} followed by one or more letters; the case of
1132 the letter is important. All options are optional.
1134 Some options expect exactly one file name to follow them. The file
1135 name may either immediately follow the option's letter (compatible
1136 with older assemblers) or it may be the next command argument (@sc{gnu}
1137 standard). These two command lines are equivalent:
1140 @value{AS} -o my-object-file.o mumble.s
1141 @value{AS} -omy-object-file.o mumble.s
1145 @section Input Files
1148 @cindex source program
1149 @cindex files, input
1150 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1151 describe the program input to one run of @command{@value{AS}}. The program may
1152 be in one or more files; how the source is partitioned into files
1153 doesn't change the meaning of the source.
1155 @c I added "con" prefix to "catenation" just to prove I can overcome my
1156 @c APL training... doc@cygnus.com
1157 The source program is a concatenation of the text in all the files, in the
1160 @c man begin DESCRIPTION
1161 Each time you run @command{@value{AS}} it assembles exactly one source
1162 program. The source program is made up of one or more files.
1163 (The standard input is also a file.)
1165 You give @command{@value{AS}} a command line that has zero or more input file
1166 names. The input files are read (from left file name to right). A
1167 command line argument (in any position) that has no special meaning
1168 is taken to be an input file name.
1170 If you give @command{@value{AS}} no file names it attempts to read one input file
1171 from the @command{@value{AS}} standard input, which is normally your terminal. You
1172 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1175 Use @samp{--} if you need to explicitly name the standard input file
1176 in your command line.
1178 If the source is empty, @command{@value{AS}} produces a small, empty object
1183 @subheading Filenames and Line-numbers
1185 @cindex input file linenumbers
1186 @cindex line numbers, in input files
1187 There are two ways of locating a line in the input file (or files) and
1188 either may be used in reporting error messages. One way refers to a line
1189 number in a physical file; the other refers to a line number in a
1190 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1192 @dfn{Physical files} are those files named in the command line given
1193 to @command{@value{AS}}.
1195 @dfn{Logical files} are simply names declared explicitly by assembler
1196 directives; they bear no relation to physical files. Logical file names help
1197 error messages reflect the original source file, when @command{@value{AS}} source
1198 is itself synthesized from other files. @command{@value{AS}} understands the
1199 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1200 @ref{File,,@code{.file}}.
1203 @section Output (Object) File
1209 Every time you run @command{@value{AS}} it produces an output file, which is
1210 your assembly language program translated into numbers. This file
1211 is the object file. Its default name is
1219 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1221 You can give it another name by using the @option{-o} option. Conventionally,
1222 object file names end with @file{.o}. The default name is used for historical
1223 reasons: older assemblers were capable of assembling self-contained programs
1224 directly into a runnable program. (For some formats, this isn't currently
1225 possible, but it can be done for the @code{a.out} format.)
1229 The object file is meant for input to the linker @code{@value{LD}}. It contains
1230 assembled program code, information to help @code{@value{LD}} integrate
1231 the assembled program into a runnable file, and (optionally) symbolic
1232 information for the debugger.
1234 @c link above to some info file(s) like the description of a.out.
1235 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1238 @section Error and Warning Messages
1240 @c man begin DESCRIPTION
1242 @cindex error messages
1243 @cindex warning messages
1244 @cindex messages from assembler
1245 @command{@value{AS}} may write warnings and error messages to the standard error
1246 file (usually your terminal). This should not happen when a compiler
1247 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1248 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1249 grave problem that stops the assembly.
1253 @cindex format of warning messages
1254 Warning messages have the format
1257 file_name:@b{NNN}:Warning Message Text
1261 @cindex line numbers, in warnings/errors
1262 (where @b{NNN} is a line number). If a logical file name has been given
1263 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1264 the current input file is used. If a logical line number was given
1266 (@pxref{Line,,@code{.line}})
1270 (@pxref{Line,,@code{.line}})
1273 (@pxref{Ln,,@code{.ln}})
1276 then it is used to calculate the number printed,
1277 otherwise the actual line in the current source file is printed. The
1278 message text is intended to be self explanatory (in the grand Unix
1281 @cindex format of error messages
1282 Error messages have the format
1284 file_name:@b{NNN}:FATAL:Error Message Text
1286 The file name and line number are derived as for warning
1287 messages. The actual message text may be rather less explanatory
1288 because many of them aren't supposed to happen.
1291 @chapter Command-Line Options
1293 @cindex options, all versions of assembler
1294 This chapter describes command-line options available in @emph{all}
1295 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1297 to the @value{TARGET}.
1300 to particular machine architectures.
1303 @c man begin DESCRIPTION
1305 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1306 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1307 The assembler arguments must be separated from each other (and the @samp{-Wa})
1308 by commas. For example:
1311 gcc -c -g -O -Wa,-alh,-L file.c
1315 This passes two options to the assembler: @samp{-alh} (emit a listing to
1316 standard output with with high-level and assembly source) and @samp{-L} (retain
1317 local symbols in the symbol table).
1319 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1320 command-line options are automatically passed to the assembler by the compiler.
1321 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1322 precisely what options it passes to each compilation pass, including the
1328 * a:: -a[cdhlns] enable listings
1329 * D:: -D for compatibility
1330 * f:: -f to work faster
1331 * I:: -I for .include search path
1332 @ifclear DIFF-TBL-KLUGE
1333 * K:: -K for compatibility
1335 @ifset DIFF-TBL-KLUGE
1336 * K:: -K for difference tables
1339 * L:: -L to retain local labels
1340 * listing:: --listing-XXX to configure listing output
1341 * M:: -M or --mri to assemble in MRI compatibility mode
1342 * MD:: --MD for dependency tracking
1343 * o:: -o to name the object file
1344 * R:: -R to join data and text sections
1345 * statistics:: --statistics to see statistics about assembly
1346 * traditional-format:: --traditional-format for compatible output
1347 * v:: -v to announce version
1348 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1349 * Z:: -Z to make object file even after errors
1353 @section Enable Listings: @option{-a[cdhlns]}
1362 @cindex listings, enabling
1363 @cindex assembly listings, enabling
1365 These options enable listing output from the assembler. By itself,
1366 @samp{-a} requests high-level, assembly, and symbols listing.
1367 You can use other letters to select specific options for the list:
1368 @samp{-ah} requests a high-level language listing,
1369 @samp{-al} requests an output-program assembly listing, and
1370 @samp{-as} requests a symbol table listing.
1371 High-level listings require that a compiler debugging option like
1372 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1375 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1376 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1377 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1378 omitted from the listing.
1380 Use the @samp{-ad} option to omit debugging directives from the
1383 Once you have specified one of these options, you can further control
1384 listing output and its appearance using the directives @code{.list},
1385 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1387 The @samp{-an} option turns off all forms processing.
1388 If you do not request listing output with one of the @samp{-a} options, the
1389 listing-control directives have no effect.
1391 The letters after @samp{-a} may be combined into one option,
1392 @emph{e.g.}, @samp{-aln}.
1394 Note if the assembler source is coming from the standard input (eg because it
1395 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1396 is being used) then the listing will not contain any comments or preprocessor
1397 directives. This is because the listing code buffers input source lines from
1398 stdin only after they have been preprocessed by the assembler. This reduces
1399 memory usage and makes the code more efficient.
1402 @section @option{-D}
1405 This option has no effect whatsoever, but it is accepted to make it more
1406 likely that scripts written for other assemblers also work with
1407 @command{@value{AS}}.
1410 @section Work Faster: @option{-f}
1413 @cindex trusted compiler
1414 @cindex faster processing (@option{-f})
1415 @samp{-f} should only be used when assembling programs written by a
1416 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1417 and comment preprocessing on
1418 the input file(s) before assembling them. @xref{Preprocessing,
1422 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1423 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1428 @section @code{.include} search path: @option{-I} @var{path}
1430 @kindex -I @var{path}
1431 @cindex paths for @code{.include}
1432 @cindex search path for @code{.include}
1433 @cindex @code{include} directive search path
1434 Use this option to add a @var{path} to the list of directories
1435 @command{@value{AS}} searches for files specified in @code{.include}
1436 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1437 many times as necessary to include a variety of paths. The current
1438 working directory is always searched first; after that, @command{@value{AS}}
1439 searches any @samp{-I} directories in the same order as they were
1440 specified (left to right) on the command line.
1443 @section Difference Tables: @option{-K}
1446 @ifclear DIFF-TBL-KLUGE
1447 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1448 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1449 where it can be used to warn when the assembler alters the machine code
1450 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1451 family does not have the addressing limitations that sometimes lead to this
1452 alteration on other platforms.
1455 @ifset DIFF-TBL-KLUGE
1456 @cindex difference tables, warning
1457 @cindex warning for altered difference tables
1458 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1459 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1460 You can use the @samp{-K} option if you want a warning issued when this
1465 @section Include Local Labels: @option{-L}
1468 @cindex local labels, retaining in output
1469 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1470 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1471 debugging, because they are intended for the use of programs (like
1472 compilers) that compose assembler programs, not for your notice.
1473 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1474 normally debug with them.
1476 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1477 in the object file. Usually if you do this you also tell the linker
1478 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1480 By default, a local label is any label beginning with @samp{L}, but each
1481 target is allowed to redefine the local label prefix.
1483 On the HPPA local labels begin with @samp{L$}.
1487 @section Configuring listing output: @option{--listing}
1489 The listing feature of the assembler can be enabled via the command line switch
1490 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1491 hex dump of the corresponding locations in the output object file, and displays
1492 them as a listing file. The format of this listing can be controlled by pseudo
1493 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1494 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1497 @item --listing-lhs-width=@samp{number}
1498 @kindex --listing-lhs-width
1499 @cindex Width of first line disassembly output
1500 Sets the maximum width, in words, of the first line of the hex byte dump. This
1501 dump appears on the left hand side of the listing output.
1503 @item --listing-lhs-width2=@samp{number}
1504 @kindex --listing-lhs-width2
1505 @cindex Width of continuation lines of disassembly output
1506 Sets the maximum width, in words, of any further lines of the hex byte dump for
1507 a given inut source line. If this value is not specified, it defaults to being
1508 the same as the value specified for @samp{--listing-lhs-width}. If neither
1509 switch is used the default is to one.
1511 @item --listing-rhs-width=@samp{number}
1512 @kindex --listing-rhs-width
1513 @cindex Width of source line output
1514 Sets the maximum width, in characters, of the source line that is displayed
1515 alongside the hex dump. The default value for this parameter is 100. The
1516 source line is displayed on the right hand side of the listing output.
1518 @item --listing-cont-lines=@samp{number}
1519 @kindex --listing-cont-lines
1520 @cindex Maximum number of continuation lines
1521 Sets the maximum number of continuation lines of hex dump that will be
1522 displayed for a given single line of source input. The default value is 4.
1526 @section Assemble in MRI Compatibility Mode: @option{-M}
1529 @cindex MRI compatibility mode
1530 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1531 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1532 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1533 configured target) assembler from Microtec Research. The exact nature of the
1534 MRI syntax will not be documented here; see the MRI manuals for more
1535 information. Note in particular that the handling of macros and macro
1536 arguments is somewhat different. The purpose of this option is to permit
1537 assembling existing MRI assembler code using @command{@value{AS}}.
1539 The MRI compatibility is not complete. Certain operations of the MRI assembler
1540 depend upon its object file format, and can not be supported using other object
1541 file formats. Supporting these would require enhancing each object file format
1542 individually. These are:
1545 @item global symbols in common section
1547 The m68k MRI assembler supports common sections which are merged by the linker.
1548 Other object file formats do not support this. @command{@value{AS}} handles
1549 common sections by treating them as a single common symbol. It permits local
1550 symbols to be defined within a common section, but it can not support global
1551 symbols, since it has no way to describe them.
1553 @item complex relocations
1555 The MRI assemblers support relocations against a negated section address, and
1556 relocations which combine the start addresses of two or more sections. These
1557 are not support by other object file formats.
1559 @item @code{END} pseudo-op specifying start address
1561 The MRI @code{END} pseudo-op permits the specification of a start address.
1562 This is not supported by other object file formats. The start address may
1563 instead be specified using the @option{-e} option to the linker, or in a linker
1566 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1568 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1569 name to the output file. This is not supported by other object file formats.
1571 @item @code{ORG} pseudo-op
1573 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1574 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1575 which changes the location within the current section. Absolute sections are
1576 not supported by other object file formats. The address of a section may be
1577 assigned within a linker script.
1580 There are some other features of the MRI assembler which are not supported by
1581 @command{@value{AS}}, typically either because they are difficult or because they
1582 seem of little consequence. Some of these may be supported in future releases.
1586 @item EBCDIC strings
1588 EBCDIC strings are not supported.
1590 @item packed binary coded decimal
1592 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1593 and @code{DCB.P} pseudo-ops are not supported.
1595 @item @code{FEQU} pseudo-op
1597 The m68k @code{FEQU} pseudo-op is not supported.
1599 @item @code{NOOBJ} pseudo-op
1601 The m68k @code{NOOBJ} pseudo-op is not supported.
1603 @item @code{OPT} branch control options
1605 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1606 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1607 relaxes all branches, whether forward or backward, to an appropriate size, so
1608 these options serve no purpose.
1610 @item @code{OPT} list control options
1612 The following m68k @code{OPT} list control options are ignored: @code{C},
1613 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1614 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1616 @item other @code{OPT} options
1618 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1619 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1621 @item @code{OPT} @code{D} option is default
1623 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1624 @code{OPT NOD} may be used to turn it off.
1626 @item @code{XREF} pseudo-op.
1628 The m68k @code{XREF} pseudo-op is ignored.
1630 @item @code{.debug} pseudo-op
1632 The i960 @code{.debug} pseudo-op is not supported.
1634 @item @code{.extended} pseudo-op
1636 The i960 @code{.extended} pseudo-op is not supported.
1638 @item @code{.list} pseudo-op.
1640 The various options of the i960 @code{.list} pseudo-op are not supported.
1642 @item @code{.optimize} pseudo-op
1644 The i960 @code{.optimize} pseudo-op is not supported.
1646 @item @code{.output} pseudo-op
1648 The i960 @code{.output} pseudo-op is not supported.
1650 @item @code{.setreal} pseudo-op
1652 The i960 @code{.setreal} pseudo-op is not supported.
1657 @section Dependency tracking: @option{--MD}
1660 @cindex dependency tracking
1663 @command{@value{AS}} can generate a dependency file for the file it creates. This
1664 file consists of a single rule suitable for @code{make} describing the
1665 dependencies of the main source file.
1667 The rule is written to the file named in its argument.
1669 This feature is used in the automatic updating of makefiles.
1672 @section Name the Object File: @option{-o}
1675 @cindex naming object file
1676 @cindex object file name
1677 There is always one object file output when you run @command{@value{AS}}. By
1678 default it has the name
1681 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1695 You use this option (which takes exactly one filename) to give the
1696 object file a different name.
1698 Whatever the object file is called, @command{@value{AS}} overwrites any
1699 existing file of the same name.
1702 @section Join Data and Text Sections: @option{-R}
1705 @cindex data and text sections, joining
1706 @cindex text and data sections, joining
1707 @cindex joining text and data sections
1708 @cindex merging text and data sections
1709 @option{-R} tells @command{@value{AS}} to write the object file as if all
1710 data-section data lives in the text section. This is only done at
1711 the very last moment: your binary data are the same, but data
1712 section parts are relocated differently. The data section part of
1713 your object file is zero bytes long because all its bytes are
1714 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1716 When you specify @option{-R} it would be possible to generate shorter
1717 address displacements (because we do not have to cross between text and
1718 data section). We refrain from doing this simply for compatibility with
1719 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1722 When @command{@value{AS}} is configured for COFF output,
1723 this option is only useful if you use sections named @samp{.text} and
1728 @option{-R} is not supported for any of the HPPA targets. Using
1729 @option{-R} generates a warning from @command{@value{AS}}.
1733 @section Display Assembly Statistics: @option{--statistics}
1735 @kindex --statistics
1736 @cindex statistics, about assembly
1737 @cindex time, total for assembly
1738 @cindex space used, maximum for assembly
1739 Use @samp{--statistics} to display two statistics about the resources used by
1740 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1741 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1744 @node traditional-format
1745 @section Compatible output: @option{--traditional-format}
1747 @kindex --traditional-format
1748 For some targets, the output of @command{@value{AS}} is different in some ways
1749 from the output of some existing assembler. This switch requests
1750 @command{@value{AS}} to use the traditional format instead.
1752 For example, it disables the exception frame optimizations which
1753 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1756 @section Announce Version: @option{-v}
1760 @cindex assembler version
1761 @cindex version of assembler
1762 You can find out what version of as is running by including the
1763 option @samp{-v} (which you can also spell as @samp{-version}) on the
1767 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1769 @command{@value{AS}} should never give a warning or error message when
1770 assembling compiler output. But programs written by people often
1771 cause @command{@value{AS}} to give a warning that a particular assumption was
1772 made. All such warnings are directed to the standard error file.
1775 @kindex @samp{--no-warn}
1776 @cindex suppressing warnings
1777 @cindex warnings, suppressing
1778 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1779 This only affects the warning messages: it does not change any particular of
1780 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1783 @kindex @samp{--fatal-warnings}
1784 @cindex errors, caused by warnings
1785 @cindex warnings, causing error
1786 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1787 files that generate warnings to be in error.
1789 @kindex @samp{--warn}
1790 @cindex warnings, switching on
1791 You can switch these options off again by specifying @option{--warn}, which
1792 causes warnings to be output as usual.
1795 @section Generate Object File in Spite of Errors: @option{-Z}
1796 @cindex object file, after errors
1797 @cindex errors, continuing after
1798 After an error message, @command{@value{AS}} normally produces no output. If for
1799 some reason you are interested in object file output even after
1800 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1801 option. If there are any errors, @command{@value{AS}} continues anyways, and
1802 writes an object file after a final warning message of the form @samp{@var{n}
1803 errors, @var{m} warnings, generating bad object file.}
1808 @cindex machine-independent syntax
1809 @cindex syntax, machine-independent
1810 This chapter describes the machine-independent syntax allowed in a
1811 source file. @command{@value{AS}} syntax is similar to what many other
1812 assemblers use; it is inspired by the BSD 4.2
1817 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1821 * Preprocessing:: Preprocessing
1822 * Whitespace:: Whitespace
1823 * Comments:: Comments
1824 * Symbol Intro:: Symbols
1825 * Statements:: Statements
1826 * Constants:: Constants
1830 @section Preprocessing
1832 @cindex preprocessing
1833 The @command{@value{AS}} internal preprocessor:
1835 @cindex whitespace, removed by preprocessor
1837 adjusts and removes extra whitespace. It leaves one space or tab before
1838 the keywords on a line, and turns any other whitespace on the line into
1841 @cindex comments, removed by preprocessor
1843 removes all comments, replacing them with a single space, or an
1844 appropriate number of newlines.
1846 @cindex constants, converted by preprocessor
1848 converts character constants into the appropriate numeric values.
1851 It does not do macro processing, include file handling, or
1852 anything else you may get from your C compiler's preprocessor. You can
1853 do include file processing with the @code{.include} directive
1854 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1855 to get other ``CPP'' style preprocessing, by giving the input file a
1856 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1857 Output, gcc.info, Using GNU CC}.
1859 Excess whitespace, comments, and character constants
1860 cannot be used in the portions of the input text that are not
1863 @cindex turning preprocessing on and off
1864 @cindex preprocessing, turning on and off
1867 If the first line of an input file is @code{#NO_APP} or if you use the
1868 @samp{-f} option, whitespace and comments are not removed from the input file.
1869 Within an input file, you can ask for whitespace and comment removal in
1870 specific portions of the by putting a line that says @code{#APP} before the
1871 text that may contain whitespace or comments, and putting a line that says
1872 @code{#NO_APP} after this text. This feature is mainly intend to support
1873 @code{asm} statements in compilers whose output is otherwise free of comments
1880 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1881 Whitespace is used to separate symbols, and to make programs neater for
1882 people to read. Unless within character constants
1883 (@pxref{Characters,,Character Constants}), any whitespace means the same
1884 as exactly one space.
1890 There are two ways of rendering comments to @command{@value{AS}}. In both
1891 cases the comment is equivalent to one space.
1893 Anything from @samp{/*} through the next @samp{*/} is a comment.
1894 This means you may not nest these comments.
1898 The only way to include a newline ('\n') in a comment
1899 is to use this sort of comment.
1902 /* This sort of comment does not nest. */
1905 @cindex line comment character
1906 Anything from the @dfn{line comment} character to the next newline
1907 is considered a comment and is ignored. The line comment character is
1909 @samp{;} for the AMD 29K family;
1912 @samp{;} on the ARC;
1915 @samp{@@} on the ARM;
1918 @samp{;} for the H8/300 family;
1921 @samp{!} for the H8/500 family;
1924 @samp{;} for the HPPA;
1927 @samp{#} on the i386 and x86-64;
1930 @samp{#} on the i960;
1933 @samp{;} for the PDP-11;
1936 @samp{;} for picoJava;
1939 @samp{;} for Motorola PowerPC;
1942 @samp{!} for the Hitachi SH;
1945 @samp{!} on the SPARC;
1948 @samp{#} on the m32r;
1951 @samp{|} on the 680x0;
1954 @samp{#} on the 68HC11 and 68HC12;
1957 @samp{;} on the M880x0;
1960 @samp{#} on the Vax;
1963 @samp{!} for the Z8000;
1966 @samp{#} on the V850;
1968 see @ref{Machine Dependencies}. @refill
1969 @c FIXME What about i860?
1972 On some machines there are two different line comment characters. One
1973 character only begins a comment if it is the first non-whitespace character on
1974 a line, while the other always begins a comment.
1978 The V850 assembler also supports a double dash as starting a comment that
1979 extends to the end of the line.
1985 @cindex lines starting with @code{#}
1986 @cindex logical line numbers
1987 To be compatible with past assemblers, lines that begin with @samp{#} have a
1988 special interpretation. Following the @samp{#} should be an absolute
1989 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1990 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1991 new logical file name. The rest of the line, if any, should be whitespace.
1993 If the first non-whitespace characters on the line are not numeric,
1994 the line is ignored. (Just like a comment.)
1997 # This is an ordinary comment.
1998 # 42-6 "new_file_name" # New logical file name
1999 # This is logical line # 36.
2001 This feature is deprecated, and may disappear from future versions
2002 of @command{@value{AS}}.
2007 @cindex characters used in symbols
2008 @ifclear SPECIAL-SYMS
2009 A @dfn{symbol} is one or more characters chosen from the set of all
2010 letters (both upper and lower case), digits and the three characters
2016 A @dfn{symbol} is one or more characters chosen from the set of all
2017 letters (both upper and lower case), digits and the three characters
2018 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2024 On most machines, you can also use @code{$} in symbol names; exceptions
2025 are noted in @ref{Machine Dependencies}.
2027 No symbol may begin with a digit. Case is significant.
2028 There is no length limit: all characters are significant. Symbols are
2029 delimited by characters not in that set, or by the beginning of a file
2030 (since the source program must end with a newline, the end of a file is
2031 not a possible symbol delimiter). @xref{Symbols}.
2032 @cindex length of symbols
2037 @cindex statements, structure of
2038 @cindex line separator character
2039 @cindex statement separator character
2041 @ifclear abnormal-separator
2042 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2043 semicolon (@samp{;}). The newline or semicolon is considered part of
2044 the preceding statement. Newlines and semicolons within character
2045 constants are an exception: they do not end statements.
2047 @ifset abnormal-separator
2049 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2050 sign (@samp{@@}). The newline or at sign is considered part of the
2051 preceding statement. Newlines and at signs within character constants
2052 are an exception: they do not end statements.
2055 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2056 point (@samp{!}). The newline or exclamation point is considered part of the
2057 preceding statement. Newlines and exclamation points within character
2058 constants are an exception: they do not end statements.
2061 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2062 H8/300) a dollar sign (@samp{$}); or (for the
2065 (@samp{;}). The newline or separator character is considered part of
2066 the preceding statement. Newlines and separators within character
2067 constants are an exception: they do not end statements.
2072 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2073 separator character. (The line separator is usually @samp{;}, unless
2074 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2075 newline or separator character is considered part of the preceding
2076 statement. Newlines and separators within character constants are an
2077 exception: they do not end statements.
2080 @cindex newline, required at file end
2081 @cindex EOF, newline must precede
2082 It is an error to end any statement with end-of-file: the last
2083 character of any input file should be a newline.@refill
2085 An empty statement is allowed, and may include whitespace. It is ignored.
2087 @cindex instructions and directives
2088 @cindex directives and instructions
2089 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2090 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2092 A statement begins with zero or more labels, optionally followed by a
2093 key symbol which determines what kind of statement it is. The key
2094 symbol determines the syntax of the rest of the statement. If the
2095 symbol begins with a dot @samp{.} then the statement is an assembler
2096 directive: typically valid for any computer. If the symbol begins with
2097 a letter the statement is an assembly language @dfn{instruction}: it
2098 assembles into a machine language instruction.
2100 Different versions of @command{@value{AS}} for different computers
2101 recognize different instructions. In fact, the same symbol may
2102 represent a different instruction in a different computer's assembly
2106 @cindex @code{:} (label)
2107 @cindex label (@code{:})
2108 A label is a symbol immediately followed by a colon (@code{:}).
2109 Whitespace before a label or after a colon is permitted, but you may not
2110 have whitespace between a label's symbol and its colon. @xref{Labels}.
2113 For HPPA targets, labels need not be immediately followed by a colon, but
2114 the definition of a label must begin in column zero. This also implies that
2115 only one label may be defined on each line.
2119 label: .directive followed by something
2120 another_label: # This is an empty statement.
2121 instruction operand_1, operand_2, @dots{}
2128 A constant is a number, written so that its value is known by
2129 inspection, without knowing any context. Like this:
2132 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2133 .ascii "Ring the bell\7" # A string constant.
2134 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2135 .float 0f-314159265358979323846264338327\
2136 95028841971.693993751E-40 # - pi, a flonum.
2141 * Characters:: Character Constants
2142 * Numbers:: Number Constants
2146 @subsection Character Constants
2148 @cindex character constants
2149 @cindex constants, character
2150 There are two kinds of character constants. A @dfn{character} stands
2151 for one character in one byte and its value may be used in
2152 numeric expressions. String constants (properly called string
2153 @emph{literals}) are potentially many bytes and their values may not be
2154 used in arithmetic expressions.
2158 * Chars:: Characters
2162 @subsubsection Strings
2164 @cindex string constants
2165 @cindex constants, string
2166 A @dfn{string} is written between double-quotes. It may contain
2167 double-quotes or null characters. The way to get special characters
2168 into a string is to @dfn{escape} these characters: precede them with
2169 a backslash @samp{\} character. For example @samp{\\} represents
2170 one backslash: the first @code{\} is an escape which tells
2171 @command{@value{AS}} to interpret the second character literally as a backslash
2172 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2173 escape character). The complete list of escapes follows.
2175 @cindex escape codes, character
2176 @cindex character escape codes
2179 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2181 @cindex @code{\b} (backspace character)
2182 @cindex backspace (@code{\b})
2184 Mnemonic for backspace; for ASCII this is octal code 010.
2187 @c Mnemonic for EOText; for ASCII this is octal code 004.
2189 @cindex @code{\f} (formfeed character)
2190 @cindex formfeed (@code{\f})
2192 Mnemonic for FormFeed; for ASCII this is octal code 014.
2194 @cindex @code{\n} (newline character)
2195 @cindex newline (@code{\n})
2197 Mnemonic for newline; for ASCII this is octal code 012.
2200 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2202 @cindex @code{\r} (carriage return character)
2203 @cindex carriage return (@code{\r})
2205 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2208 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2209 @c other assemblers.
2211 @cindex @code{\t} (tab)
2212 @cindex tab (@code{\t})
2214 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2217 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2218 @c @item \x @var{digit} @var{digit} @var{digit}
2219 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2221 @cindex @code{\@var{ddd}} (octal character code)
2222 @cindex octal character code (@code{\@var{ddd}})
2223 @item \ @var{digit} @var{digit} @var{digit}
2224 An octal character code. The numeric code is 3 octal digits.
2225 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2226 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2228 @cindex @code{\@var{xd...}} (hex character code)
2229 @cindex hex character code (@code{\@var{xd...}})
2230 @item \@code{x} @var{hex-digits...}
2231 A hex character code. All trailing hex digits are combined. Either upper or
2232 lower case @code{x} works.
2234 @cindex @code{\\} (@samp{\} character)
2235 @cindex backslash (@code{\\})
2237 Represents one @samp{\} character.
2240 @c Represents one @samp{'} (accent acute) character.
2241 @c This is needed in single character literals
2242 @c (@xref{Characters,,Character Constants}.) to represent
2245 @cindex @code{\"} (doublequote character)
2246 @cindex doublequote (@code{\"})
2248 Represents one @samp{"} character. Needed in strings to represent
2249 this character, because an unescaped @samp{"} would end the string.
2251 @item \ @var{anything-else}
2252 Any other character when escaped by @kbd{\} gives a warning, but
2253 assembles as if the @samp{\} was not present. The idea is that if
2254 you used an escape sequence you clearly didn't want the literal
2255 interpretation of the following character. However @command{@value{AS}} has no
2256 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2257 code and warns you of the fact.
2260 Which characters are escapable, and what those escapes represent,
2261 varies widely among assemblers. The current set is what we think
2262 the BSD 4.2 assembler recognizes, and is a subset of what most C
2263 compilers recognize. If you are in doubt, do not use an escape
2267 @subsubsection Characters
2269 @cindex single character constant
2270 @cindex character, single
2271 @cindex constant, single character
2272 A single character may be written as a single quote immediately
2273 followed by that character. The same escapes apply to characters as
2274 to strings. So if you want to write the character backslash, you
2275 must write @kbd{'\\} where the first @code{\} escapes the second
2276 @code{\}. As you can see, the quote is an acute accent, not a
2277 grave accent. A newline
2279 @ifclear abnormal-separator
2280 (or semicolon @samp{;})
2282 @ifset abnormal-separator
2284 (or at sign @samp{@@})
2287 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2293 immediately following an acute accent is taken as a literal character
2294 and does not count as the end of a statement. The value of a character
2295 constant in a numeric expression is the machine's byte-wide code for
2296 that character. @command{@value{AS}} assumes your character code is ASCII:
2297 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2300 @subsection Number Constants
2302 @cindex constants, number
2303 @cindex number constants
2304 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2305 are stored in the target machine. @emph{Integers} are numbers that
2306 would fit into an @code{int} in the C language. @emph{Bignums} are
2307 integers, but they are stored in more than 32 bits. @emph{Flonums}
2308 are floating point numbers, described below.
2311 * Integers:: Integers
2316 * Bit Fields:: Bit Fields
2322 @subsubsection Integers
2324 @cindex constants, integer
2326 @cindex binary integers
2327 @cindex integers, binary
2328 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2329 the binary digits @samp{01}.
2331 @cindex octal integers
2332 @cindex integers, octal
2333 An octal integer is @samp{0} followed by zero or more of the octal
2334 digits (@samp{01234567}).
2336 @cindex decimal integers
2337 @cindex integers, decimal
2338 A decimal integer starts with a non-zero digit followed by zero or
2339 more digits (@samp{0123456789}).
2341 @cindex hexadecimal integers
2342 @cindex integers, hexadecimal
2343 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2344 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2346 Integers have the usual values. To denote a negative integer, use
2347 the prefix operator @samp{-} discussed under expressions
2348 (@pxref{Prefix Ops,,Prefix Operators}).
2351 @subsubsection Bignums
2354 @cindex constants, bignum
2355 A @dfn{bignum} has the same syntax and semantics as an integer
2356 except that the number (or its negative) takes more than 32 bits to
2357 represent in binary. The distinction is made because in some places
2358 integers are permitted while bignums are not.
2361 @subsubsection Flonums
2363 @cindex floating point numbers
2364 @cindex constants, floating point
2366 @cindex precision, floating point
2367 A @dfn{flonum} represents a floating point number. The translation is
2368 indirect: a decimal floating point number from the text is converted by
2369 @command{@value{AS}} to a generic binary floating point number of more than
2370 sufficient precision. This generic floating point number is converted
2371 to a particular computer's floating point format (or formats) by a
2372 portion of @command{@value{AS}} specialized to that computer.
2374 A flonum is written by writing (in order)
2379 (@samp{0} is optional on the HPPA.)
2383 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2385 @kbd{e} is recommended. Case is not important.
2387 @c FIXME: verify if flonum syntax really this vague for most cases
2388 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2389 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2392 On the H8/300, H8/500,
2394 and AMD 29K architectures, the letter must be
2395 one of the letters @samp{DFPRSX} (in upper or lower case).
2397 On the ARC, the letter must be one of the letters @samp{DFRS}
2398 (in upper or lower case).
2400 On the Intel 960 architecture, the letter must be
2401 one of the letters @samp{DFT} (in upper or lower case).
2403 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2407 One of the letters @samp{DFPRSX} (in upper or lower case).
2410 One of the letters @samp{DFRS} (in upper or lower case).
2413 One of the letters @samp{DFPRSX} (in upper or lower case).
2416 The letter @samp{E} (upper case only).
2419 One of the letters @samp{DFT} (in upper or lower case).
2424 An optional sign: either @samp{+} or @samp{-}.
2427 An optional @dfn{integer part}: zero or more decimal digits.
2430 An optional @dfn{fractional part}: @samp{.} followed by zero
2431 or more decimal digits.
2434 An optional exponent, consisting of:
2438 An @samp{E} or @samp{e}.
2439 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2440 @c principle this can perfectly well be different on different targets.
2442 Optional sign: either @samp{+} or @samp{-}.
2444 One or more decimal digits.
2449 At least one of the integer part or the fractional part must be
2450 present. The floating point number has the usual base-10 value.
2452 @command{@value{AS}} does all processing using integers. Flonums are computed
2453 independently of any floating point hardware in the computer running
2454 @command{@value{AS}}.
2458 @c Bit fields are written as a general facility but are also controlled
2459 @c by a conditional-compilation flag---which is as of now (21mar91)
2460 @c turned on only by the i960 config of GAS.
2462 @subsubsection Bit Fields
2465 @cindex constants, bit field
2466 You can also define numeric constants as @dfn{bit fields}.
2467 specify two numbers separated by a colon---
2469 @var{mask}:@var{value}
2472 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2475 The resulting number is then packed
2477 @c this conditional paren in case bit fields turned on elsewhere than 960
2478 (in host-dependent byte order)
2480 into a field whose width depends on which assembler directive has the
2481 bit-field as its argument. Overflow (a result from the bitwise and
2482 requiring more binary digits to represent) is not an error; instead,
2483 more constants are generated, of the specified width, beginning with the
2484 least significant digits.@refill
2486 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2487 @code{.short}, and @code{.word} accept bit-field arguments.
2492 @chapter Sections and Relocation
2497 * Secs Background:: Background
2498 * Ld Sections:: Linker Sections
2499 * As Sections:: Assembler Internal Sections
2500 * Sub-Sections:: Sub-Sections
2504 @node Secs Background
2507 Roughly, a section is a range of addresses, with no gaps; all data
2508 ``in'' those addresses is treated the same for some particular purpose.
2509 For example there may be a ``read only'' section.
2511 @cindex linker, and assembler
2512 @cindex assembler, and linker
2513 The linker @code{@value{LD}} reads many object files (partial programs) and
2514 combines their contents to form a runnable program. When @command{@value{AS}}
2515 emits an object file, the partial program is assumed to start at address 0.
2516 @code{@value{LD}} assigns the final addresses for the partial program, so that
2517 different partial programs do not overlap. This is actually an
2518 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2521 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2522 addresses. These blocks slide to their run-time addresses as rigid
2523 units; their length does not change and neither does the order of bytes
2524 within them. Such a rigid unit is called a @emph{section}. Assigning
2525 run-time addresses to sections is called @dfn{relocation}. It includes
2526 the task of adjusting mentions of object-file addresses so they refer to
2527 the proper run-time addresses.
2529 For the H8/300 and H8/500,
2530 and for the Hitachi SH,
2531 @command{@value{AS}} pads sections if needed to
2532 ensure they end on a word (sixteen bit) boundary.
2535 @cindex standard assembler sections
2536 An object file written by @command{@value{AS}} has at least three sections, any
2537 of which may be empty. These are named @dfn{text}, @dfn{data} and
2542 When it generates COFF output,
2544 @command{@value{AS}} can also generate whatever other named sections you specify
2545 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2546 If you do not use any directives that place output in the @samp{.text}
2547 or @samp{.data} sections, these sections still exist, but are empty.
2552 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2554 @command{@value{AS}} can also generate whatever other named sections you
2555 specify using the @samp{.space} and @samp{.subspace} directives. See
2556 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2557 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2558 assembler directives.
2561 Additionally, @command{@value{AS}} uses different names for the standard
2562 text, data, and bss sections when generating SOM output. Program text
2563 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2564 BSS into @samp{$BSS$}.
2568 Within the object file, the text section starts at address @code{0}, the
2569 data section follows, and the bss section follows the data section.
2572 When generating either SOM or ELF output files on the HPPA, the text
2573 section starts at address @code{0}, the data section at address
2574 @code{0x4000000}, and the bss section follows the data section.
2577 To let @code{@value{LD}} know which data changes when the sections are
2578 relocated, and how to change that data, @command{@value{AS}} also writes to the
2579 object file details of the relocation needed. To perform relocation
2580 @code{@value{LD}} must know, each time an address in the object
2584 Where in the object file is the beginning of this reference to
2587 How long (in bytes) is this reference?
2589 Which section does the address refer to? What is the numeric value of
2591 (@var{address}) @minus{} (@var{start-address of section})?
2594 Is the reference to an address ``Program-Counter relative''?
2597 @cindex addresses, format of
2598 @cindex section-relative addressing
2599 In fact, every address @command{@value{AS}} ever uses is expressed as
2601 (@var{section}) + (@var{offset into section})
2604 Further, most expressions @command{@value{AS}} computes have this section-relative
2607 (For some object formats, such as SOM for the HPPA, some expressions are
2608 symbol-relative instead.)
2611 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2612 @var{N} into section @var{secname}.''
2614 Apart from text, data and bss sections you need to know about the
2615 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2616 addresses in the absolute section remain unchanged. For example, address
2617 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2618 @code{@value{LD}}. Although the linker never arranges two partial programs'
2619 data sections with overlapping addresses after linking, @emph{by definition}
2620 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2621 part of a program is always the same address when the program is running as
2622 address @code{@{absolute@ 239@}} in any other part of the program.
2624 The idea of sections is extended to the @dfn{undefined} section. Any
2625 address whose section is unknown at assembly time is by definition
2626 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2627 Since numbers are always defined, the only way to generate an undefined
2628 address is to mention an undefined symbol. A reference to a named
2629 common block would be such a symbol: its value is unknown at assembly
2630 time so it has section @emph{undefined}.
2632 By analogy the word @emph{section} is used to describe groups of sections in
2633 the linked program. @code{@value{LD}} puts all partial programs' text
2634 sections in contiguous addresses in the linked program. It is
2635 customary to refer to the @emph{text section} of a program, meaning all
2636 the addresses of all partial programs' text sections. Likewise for
2637 data and bss sections.
2639 Some sections are manipulated by @code{@value{LD}}; others are invented for
2640 use of @command{@value{AS}} and have no meaning except during assembly.
2643 @section Linker Sections
2644 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2649 @cindex named sections
2650 @cindex sections, named
2651 @item named sections
2654 @cindex text section
2655 @cindex data section
2659 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2660 separate but equal sections. Anything you can say of one section is
2663 When the program is running, however, it is
2664 customary for the text section to be unalterable. The
2665 text section is often shared among processes: it contains
2666 instructions, constants and the like. The data section of a running
2667 program is usually alterable: for example, C variables would be stored
2668 in the data section.
2673 This section contains zeroed bytes when your program begins running. It
2674 is used to hold uninitialized variables or common storage. The length of
2675 each partial program's bss section is important, but because it starts
2676 out containing zeroed bytes there is no need to store explicit zero
2677 bytes in the object file. The bss section was invented to eliminate
2678 those explicit zeros from object files.
2680 @cindex absolute section
2681 @item absolute section
2682 Address 0 of this section is always ``relocated'' to runtime address 0.
2683 This is useful if you want to refer to an address that @code{@value{LD}} must
2684 not change when relocating. In this sense we speak of absolute
2685 addresses being ``unrelocatable'': they do not change during relocation.
2687 @cindex undefined section
2688 @item undefined section
2689 This ``section'' is a catch-all for address references to objects not in
2690 the preceding sections.
2691 @c FIXME: ref to some other doc on obj-file formats could go here.
2694 @cindex relocation example
2695 An idealized example of three relocatable sections follows.
2697 The example uses the traditional section names @samp{.text} and @samp{.data}.
2699 Memory addresses are on the horizontal axis.
2703 @c END TEXI2ROFF-KILL
2706 partial program # 1: |ttttt|dddd|00|
2713 partial program # 2: |TTT|DDD|000|
2716 +--+---+-----+--+----+---+-----+~~
2717 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2718 +--+---+-----+--+----+---+-----+~~
2720 addresses: 0 @dots{}
2727 \line{\it Partial program \#1: \hfil}
2728 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2729 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2731 \line{\it Partial program \#2: \hfil}
2732 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2733 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2735 \line{\it linked program: \hfil}
2736 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2737 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2738 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2739 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2741 \line{\it addresses: \hfil}
2745 @c END TEXI2ROFF-KILL
2748 @section Assembler Internal Sections
2750 @cindex internal assembler sections
2751 @cindex sections in messages, internal
2752 These sections are meant only for the internal use of @command{@value{AS}}. They
2753 have no meaning at run-time. You do not really need to know about these
2754 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2755 warning messages, so it might be helpful to have an idea of their
2756 meanings to @command{@value{AS}}. These sections are used to permit the
2757 value of every expression in your assembly language program to be a
2758 section-relative address.
2761 @cindex assembler internal logic error
2762 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2763 An internal assembler logic error has been found. This means there is a
2764 bug in the assembler.
2766 @cindex expr (internal section)
2768 The assembler stores complex expression internally as combinations of
2769 symbols. When it needs to represent an expression as a symbol, it puts
2770 it in the expr section.
2772 @c FIXME item transfer[t] vector preload
2773 @c FIXME item transfer[t] vector postload
2774 @c FIXME item register
2778 @section Sub-Sections
2780 @cindex numbered subsections
2781 @cindex grouping data
2787 fall into two sections: text and data.
2789 You may have separate groups of
2791 data in named sections
2795 data in named sections
2801 that you want to end up near to each other in the object file, even though they
2802 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2803 use @dfn{subsections} for this purpose. Within each section, there can be
2804 numbered subsections with values from 0 to 8192. Objects assembled into the
2805 same subsection go into the object file together with other objects in the same
2806 subsection. For example, a compiler might want to store constants in the text
2807 section, but might not want to have them interspersed with the program being
2808 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2809 section of code being output, and a @samp{.text 1} before each group of
2810 constants being output.
2812 Subsections are optional. If you do not use subsections, everything
2813 goes in subsection number zero.
2816 Each subsection is zero-padded up to a multiple of four bytes.
2817 (Subsections may be padded a different amount on different flavors
2818 of @command{@value{AS}}.)
2822 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2823 boundary (two bytes).
2824 The same is true on the Hitachi SH.
2827 @c FIXME section padding (alignment)?
2828 @c Rich Pixley says padding here depends on target obj code format; that
2829 @c doesn't seem particularly useful to say without further elaboration,
2830 @c so for now I say nothing about it. If this is a generic BFD issue,
2831 @c these paragraphs might need to vanish from this manual, and be
2832 @c discussed in BFD chapter of binutils (or some such).
2835 On the AMD 29K family, no particular padding is added to section or
2836 subsection sizes; @value{AS} forces no alignment on this platform.
2840 Subsections appear in your object file in numeric order, lowest numbered
2841 to highest. (All this to be compatible with other people's assemblers.)
2842 The object file contains no representation of subsections; @code{@value{LD}} and
2843 other programs that manipulate object files see no trace of them.
2844 They just see all your text subsections as a text section, and all your
2845 data subsections as a data section.
2847 To specify which subsection you want subsequent statements assembled
2848 into, use a numeric argument to specify it, in a @samp{.text
2849 @var{expression}} or a @samp{.data @var{expression}} statement.
2852 When generating COFF output, you
2857 can also use an extra subsection
2858 argument with arbitrary named sections: @samp{.section @var{name},
2861 @var{Expression} should be an absolute expression.
2862 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2863 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2864 begins in @code{text 0}. For instance:
2866 .text 0 # The default subsection is text 0 anyway.
2867 .ascii "This lives in the first text subsection. *"
2869 .ascii "But this lives in the second text subsection."
2871 .ascii "This lives in the data section,"
2872 .ascii "in the first data subsection."
2874 .ascii "This lives in the first text section,"
2875 .ascii "immediately following the asterisk (*)."
2878 Each section has a @dfn{location counter} incremented by one for every byte
2879 assembled into that section. Because subsections are merely a convenience
2880 restricted to @command{@value{AS}} there is no concept of a subsection location
2881 counter. There is no way to directly manipulate a location counter---but the
2882 @code{.align} directive changes it, and any label definition captures its
2883 current value. The location counter of the section where statements are being
2884 assembled is said to be the @dfn{active} location counter.
2887 @section bss Section
2890 @cindex common variable storage
2891 The bss section is used for local common variable storage.
2892 You may allocate address space in the bss section, but you may
2893 not dictate data to load into it before your program executes. When
2894 your program starts running, all the contents of the bss
2895 section are zeroed bytes.
2897 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2898 @ref{Lcomm,,@code{.lcomm}}.
2900 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2901 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2904 When assembling for a target which supports multiple sections, such as ELF or
2905 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2906 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2907 section. Typically the section will only contain symbol definitions and
2908 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2915 Symbols are a central concept: the programmer uses symbols to name
2916 things, the linker uses symbols to link, and the debugger uses symbols
2920 @cindex debuggers, and symbol order
2921 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2922 the same order they were declared. This may break some debuggers.
2927 * Setting Symbols:: Giving Symbols Other Values
2928 * Symbol Names:: Symbol Names
2929 * Dot:: The Special Dot Symbol
2930 * Symbol Attributes:: Symbol Attributes
2937 A @dfn{label} is written as a symbol immediately followed by a colon
2938 @samp{:}. The symbol then represents the current value of the
2939 active location counter, and is, for example, a suitable instruction
2940 operand. You are warned if you use the same symbol to represent two
2941 different locations: the first definition overrides any other
2945 On the HPPA, the usual form for a label need not be immediately followed by a
2946 colon, but instead must start in column zero. Only one label may be defined on
2947 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2948 provides a special directive @code{.label} for defining labels more flexibly.
2951 @node Setting Symbols
2952 @section Giving Symbols Other Values
2954 @cindex assigning values to symbols
2955 @cindex symbol values, assigning
2956 A symbol can be given an arbitrary value by writing a symbol, followed
2957 by an equals sign @samp{=}, followed by an expression
2958 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2959 directive. @xref{Set,,@code{.set}}.
2962 @section Symbol Names
2964 @cindex symbol names
2965 @cindex names, symbol
2966 @ifclear SPECIAL-SYMS
2967 Symbol names begin with a letter or with one of @samp{._}. On most
2968 machines, you can also use @code{$} in symbol names; exceptions are
2969 noted in @ref{Machine Dependencies}. That character may be followed by any
2970 string of digits, letters, dollar signs (unless otherwise noted in
2971 @ref{Machine Dependencies}), and underscores.
2974 For the AMD 29K family, @samp{?} is also allowed in the
2975 body of a symbol name, though not at its beginning.
2980 Symbol names begin with a letter or with one of @samp{._}. On the
2982 H8/500, you can also use @code{$} in symbol names. That character may
2983 be followed by any string of digits, letters, dollar signs (save on the
2984 H8/300), and underscores.
2988 Case of letters is significant: @code{foo} is a different symbol name
2991 Each symbol has exactly one name. Each name in an assembly language program
2992 refers to exactly one symbol. You may use that symbol name any number of times
2995 @subheading Local Symbol Names
2997 @cindex local symbol names
2998 @cindex symbol names, local
2999 @cindex temporary symbol names
3000 @cindex symbol names, temporary
3001 Local symbols help compilers and programmers use names temporarily.
3002 They create symbols which are guaranteed to be unique over the entire scope of
3003 the input source code and which can be referred to by a simple notation.
3004 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3005 represents any positive integer). To refer to the most recent previous
3006 definition of that symbol write @samp{@b{N}b}, using the same number as when
3007 you defined the label. To refer to the next definition of a local label, write
3008 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3011 There is no restriction on how you can use these labels, and you can reuse them
3012 too. So that it is possible to repeatedly define the same local label (using
3013 the same number @samp{@b{N}}), although you can only refer to the most recently
3014 defined local label of that number (for a backwards reference) or the next
3015 definition of a specific local label for a forward reference. It is also worth
3016 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3017 implemented in a slightly more efficient manner than the others.
3028 Which is the equivalent of:
3031 label_1: branch label_3
3032 label_2: branch label_1
3033 label_3: branch label_4
3034 label_4: branch label_3
3037 Local symbol names are only a notational device. They are immediately
3038 transformed into more conventional symbol names before the assembler uses them.
3039 The symbol names stored in the symbol table, appearing in error messages and
3040 optionally emitted to the object file. The names are constructed using these
3045 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3046 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3047 used for symbols you are never intended to see. If you use the
3048 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3049 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3050 you may use them in debugging.
3053 This is the number that was used in the local label definition. So if the
3054 label is written @samp{55:} then the number is @samp{55}.
3057 This unusual character is included so you do not accidentally invent a symbol
3058 of the same name. The character has ASCII value of @samp{\002} (control-B).
3060 @item @emph{ordinal number}
3061 This is a serial number to keep the labels distinct. The first definition of
3062 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3063 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3064 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3067 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3068 @code{3:} is named @code{L3@kbd{C-B}44}.
3070 @subheading Dollar Local Labels
3071 @cindex dollar local symbols
3073 @code{@value{AS}} also supports an even more local form of local labels called
3074 dollar labels. These labels go out of scope (ie they become undefined) as soon
3075 as a non-local label is defined. Thus they remain valid for only a small
3076 region of the input source code. Normal local labels, by contrast, remain in
3077 scope for the entire file, or until they are redefined by another occurrence of
3078 the same local label.
3080 Dollar labels are defined in exactly the same way as ordinary local labels,
3081 except that instead of being terminated by a colon, they are terminated by a
3082 dollar sign. eg @samp{@b{55$}}.
3084 They can also be distinguished from ordinary local labels by their transformed
3085 name which uses ASCII character @samp{\001} (control-A) as the magic character
3086 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3087 is named @samp{L6@kbd{C-A}5}.
3090 @section The Special Dot Symbol
3092 @cindex dot (symbol)
3093 @cindex @code{.} (symbol)
3094 @cindex current address
3095 @cindex location counter
3096 The special symbol @samp{.} refers to the current address that
3097 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3098 .long .} defines @code{melvin} to contain its own address.
3099 Assigning a value to @code{.} is treated the same as a @code{.org}
3100 directive. Thus, the expression @samp{.=.+4} is the same as saying
3101 @ifclear no-space-dir
3110 @node Symbol Attributes
3111 @section Symbol Attributes
3113 @cindex symbol attributes
3114 @cindex attributes, symbol
3115 Every symbol has, as well as its name, the attributes ``Value'' and
3116 ``Type''. Depending on output format, symbols can also have auxiliary
3119 The detailed definitions are in @file{a.out.h}.
3122 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3123 all these attributes, and probably won't warn you. This makes the
3124 symbol an externally defined symbol, which is generally what you
3128 * Symbol Value:: Value
3129 * Symbol Type:: Type
3132 * a.out Symbols:: Symbol Attributes: @code{a.out}
3136 * a.out Symbols:: Symbol Attributes: @code{a.out}
3139 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3144 * COFF Symbols:: Symbol Attributes for COFF
3147 * SOM Symbols:: Symbol Attributes for SOM
3154 @cindex value of a symbol
3155 @cindex symbol value
3156 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3157 location in the text, data, bss or absolute sections the value is the
3158 number of addresses from the start of that section to the label.
3159 Naturally for text, data and bss sections the value of a symbol changes
3160 as @code{@value{LD}} changes section base addresses during linking. Absolute
3161 symbols' values do not change during linking: that is why they are
3164 The value of an undefined symbol is treated in a special way. If it is
3165 0 then the symbol is not defined in this assembler source file, and
3166 @code{@value{LD}} tries to determine its value from other files linked into the
3167 same program. You make this kind of symbol simply by mentioning a symbol
3168 name without defining it. A non-zero value represents a @code{.comm}
3169 common declaration. The value is how much common storage to reserve, in
3170 bytes (addresses). The symbol refers to the first address of the
3176 @cindex type of a symbol
3178 The type attribute of a symbol contains relocation (section)
3179 information, any flag settings indicating that a symbol is external, and
3180 (optionally), other information for linkers and debuggers. The exact
3181 format depends on the object-code output format in use.
3186 @c The following avoids a "widow" subsection title. @group would be
3187 @c better if it were available outside examples.
3190 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3192 @cindex @code{b.out} symbol attributes
3193 @cindex symbol attributes, @code{b.out}
3194 These symbol attributes appear only when @command{@value{AS}} is configured for
3195 one of the Berkeley-descended object output formats---@code{a.out} or
3201 @subsection Symbol Attributes: @code{a.out}
3203 @cindex @code{a.out} symbol attributes
3204 @cindex symbol attributes, @code{a.out}
3210 @subsection Symbol Attributes: @code{a.out}
3212 @cindex @code{a.out} symbol attributes
3213 @cindex symbol attributes, @code{a.out}
3217 * Symbol Desc:: Descriptor
3218 * Symbol Other:: Other
3222 @subsubsection Descriptor
3224 @cindex descriptor, of @code{a.out} symbol
3225 This is an arbitrary 16-bit value. You may establish a symbol's
3226 descriptor value by using a @code{.desc} statement
3227 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3228 @command{@value{AS}}.
3231 @subsubsection Other
3233 @cindex other attribute, of @code{a.out} symbol
3234 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3239 @subsection Symbol Attributes for COFF
3241 @cindex COFF symbol attributes
3242 @cindex symbol attributes, COFF
3244 The COFF format supports a multitude of auxiliary symbol attributes;
3245 like the primary symbol attributes, they are set between @code{.def} and
3246 @code{.endef} directives.
3248 @subsubsection Primary Attributes
3250 @cindex primary attributes, COFF symbols
3251 The symbol name is set with @code{.def}; the value and type,
3252 respectively, with @code{.val} and @code{.type}.
3254 @subsubsection Auxiliary Attributes
3256 @cindex auxiliary attributes, COFF symbols
3257 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3258 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3259 information for COFF.
3264 @subsection Symbol Attributes for SOM
3266 @cindex SOM symbol attributes
3267 @cindex symbol attributes, SOM
3269 The SOM format for the HPPA supports a multitude of symbol attributes set with
3270 the @code{.EXPORT} and @code{.IMPORT} directives.
3272 The attributes are described in @cite{HP9000 Series 800 Assembly
3273 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3274 @code{EXPORT} assembler directive documentation.
3278 @chapter Expressions
3282 @cindex numeric values
3283 An @dfn{expression} specifies an address or numeric value.
3284 Whitespace may precede and/or follow an expression.
3286 The result of an expression must be an absolute number, or else an offset into
3287 a particular section. If an expression is not absolute, and there is not
3288 enough information when @command{@value{AS}} sees the expression to know its
3289 section, a second pass over the source program might be necessary to interpret
3290 the expression---but the second pass is currently not implemented.
3291 @command{@value{AS}} aborts with an error message in this situation.
3294 * Empty Exprs:: Empty Expressions
3295 * Integer Exprs:: Integer Expressions
3299 @section Empty Expressions
3301 @cindex empty expressions
3302 @cindex expressions, empty
3303 An empty expression has no value: it is just whitespace or null.
3304 Wherever an absolute expression is required, you may omit the
3305 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3306 is compatible with other assemblers.
3309 @section Integer Expressions
3311 @cindex integer expressions
3312 @cindex expressions, integer
3313 An @dfn{integer expression} is one or more @emph{arguments} delimited
3314 by @emph{operators}.
3317 * Arguments:: Arguments
3318 * Operators:: Operators
3319 * Prefix Ops:: Prefix Operators
3320 * Infix Ops:: Infix Operators
3324 @subsection Arguments
3326 @cindex expression arguments
3327 @cindex arguments in expressions
3328 @cindex operands in expressions
3329 @cindex arithmetic operands
3330 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3331 contexts arguments are sometimes called ``arithmetic operands''. In
3332 this manual, to avoid confusing them with the ``instruction operands'' of
3333 the machine language, we use the term ``argument'' to refer to parts of
3334 expressions only, reserving the word ``operand'' to refer only to machine
3335 instruction operands.
3337 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3338 @var{section} is one of text, data, bss, absolute,
3339 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3342 Numbers are usually integers.
3344 A number can be a flonum or bignum. In this case, you are warned
3345 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3346 these 32 bits are an integer. You may write integer-manipulating
3347 instructions that act on exotic constants, compatible with other
3350 @cindex subexpressions
3351 Subexpressions are a left parenthesis @samp{(} followed by an integer
3352 expression, followed by a right parenthesis @samp{)}; or a prefix
3353 operator followed by an argument.
3356 @subsection Operators
3358 @cindex operators, in expressions
3359 @cindex arithmetic functions
3360 @cindex functions, in expressions
3361 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3362 operators are followed by an argument. Infix operators appear
3363 between their arguments. Operators may be preceded and/or followed by
3367 @subsection Prefix Operator
3369 @cindex prefix operators
3370 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3371 one argument, which must be absolute.
3373 @c the tex/end tex stuff surrounding this small table is meant to make
3374 @c it align, on the printed page, with the similar table in the next
3375 @c section (which is inside an enumerate).
3377 \global\advance\leftskip by \itemindent
3382 @dfn{Negation}. Two's complement negation.
3384 @dfn{Complementation}. Bitwise not.
3388 \global\advance\leftskip by -\itemindent
3392 @subsection Infix Operators
3394 @cindex infix operators
3395 @cindex operators, permitted arguments
3396 @dfn{Infix operators} take two arguments, one on either side. Operators
3397 have precedence, but operations with equal precedence are performed left
3398 to right. Apart from @code{+} or @option{-}, both arguments must be
3399 absolute, and the result is absolute.
3402 @cindex operator precedence
3403 @cindex precedence of operators
3410 @dfn{Multiplication}.
3413 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3420 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3424 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3428 Intermediate precedence
3433 @dfn{Bitwise Inclusive Or}.
3439 @dfn{Bitwise Exclusive Or}.
3442 @dfn{Bitwise Or Not}.
3449 @cindex addition, permitted arguments
3450 @cindex plus, permitted arguments
3451 @cindex arguments for addition
3453 @dfn{Addition}. If either argument is absolute, the result has the section of
3454 the other argument. You may not add together arguments from different
3457 @cindex subtraction, permitted arguments
3458 @cindex minus, permitted arguments
3459 @cindex arguments for subtraction
3461 @dfn{Subtraction}. If the right argument is absolute, the
3462 result has the section of the left argument.
3463 If both arguments are in the same section, the result is absolute.
3464 You may not subtract arguments from different sections.
3465 @c FIXME is there still something useful to say about undefined - undefined ?
3467 @cindex comparison expressions
3468 @cindex expressions, comparison
3472 @dfn{Is Not Equal To}
3476 @dfn{Is Greater Than}
3478 @dfn{Is Greater Than Or Equal To}
3480 @dfn{Is Less Than Or Equal To}
3482 The comparison operators can be used as infix operators. A true results has a
3483 value of -1 whereas a false result has a value of 0. Note, these operators
3484 perform signed comparisons.
3487 @item Lowest Precedence
3496 These two logical operations can be used to combine the results of sub
3497 expressions. Note, unlike the comparison operators a true result returns a
3498 value of 1 but a false results does still return 0. Also note that the logical
3499 or operator has a slightly lower precedence than logical and.
3504 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3505 address; you can only have a defined section in one of the two arguments.
3508 @chapter Assembler Directives
3510 @cindex directives, machine independent
3511 @cindex pseudo-ops, machine independent
3512 @cindex machine independent directives
3513 All assembler directives have names that begin with a period (@samp{.}).
3514 The rest of the name is letters, usually in lower case.
3516 This chapter discusses directives that are available regardless of the
3517 target machine configuration for the @sc{gnu} assembler.
3519 Some machine configurations provide additional directives.
3520 @xref{Machine Dependencies}.
3523 @ifset machine-directives
3524 @xref{Machine Dependencies} for additional directives.
3529 * Abort:: @code{.abort}
3531 * ABORT:: @code{.ABORT}
3534 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3535 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3536 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3537 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3538 * Byte:: @code{.byte @var{expressions}}
3539 * Comm:: @code{.comm @var{symbol} , @var{length} }
3540 * Data:: @code{.data @var{subsection}}
3542 * Def:: @code{.def @var{name}}
3545 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3551 * Double:: @code{.double @var{flonums}}
3552 * Eject:: @code{.eject}
3553 * Else:: @code{.else}
3554 * Elseif:: @code{.elseif}
3557 * Endef:: @code{.endef}
3560 * Endfunc:: @code{.endfunc}
3561 * Endif:: @code{.endif}
3562 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3563 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3565 * Exitm:: @code{.exitm}
3566 * Extern:: @code{.extern}
3567 * Fail:: @code{.fail}
3568 @ifclear no-file-dir
3569 * File:: @code{.file @var{string}}
3572 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3573 * Float:: @code{.float @var{flonums}}
3574 * Func:: @code{.func}
3575 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3577 * Hidden:: @code{.hidden @var{names}}
3580 * hword:: @code{.hword @var{expressions}}
3581 * Ident:: @code{.ident}
3582 * If:: @code{.if @var{absolute expression}}
3583 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3584 * Include:: @code{.include "@var{file}"}
3585 * Int:: @code{.int @var{expressions}}
3587 * Internal:: @code{.internal @var{names}}
3590 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3591 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3592 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3593 * Lflags:: @code{.lflags}
3594 @ifclear no-line-dir
3595 * Line:: @code{.line @var{line-number}}
3598 * Ln:: @code{.ln @var{line-number}}
3599 * Linkonce:: @code{.linkonce [@var{type}]}
3600 * List:: @code{.list}
3601 * Long:: @code{.long @var{expressions}}
3603 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3606 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3607 * MRI:: @code{.mri @var{val}}
3608 * Nolist:: @code{.nolist}
3609 * Octa:: @code{.octa @var{bignums}}
3610 * Org:: @code{.org @var{new-lc} , @var{fill}}
3611 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3613 * PopSection:: @code{.popsection}
3614 * Previous:: @code{.previous}
3617 * Print:: @code{.print @var{string}}
3619 * Protected:: @code{.protected @var{names}}
3622 * Psize:: @code{.psize @var{lines}, @var{columns}}
3623 * Purgem:: @code{.purgem @var{name}}
3625 * PushSection:: @code{.pushsection @var{name}}
3628 * Quad:: @code{.quad @var{bignums}}
3629 * Rept:: @code{.rept @var{count}}
3630 * Sbttl:: @code{.sbttl "@var{subheading}"}
3632 * Scl:: @code{.scl @var{class}}
3633 * Section:: @code{.section @var{name}, @var{subsection}}
3636 * Set:: @code{.set @var{symbol}, @var{expression}}
3637 * Short:: @code{.short @var{expressions}}
3638 * Single:: @code{.single @var{flonums}}
3639 * Size:: @code{.size [@var{name} , @var{expression}]}
3640 * Skip:: @code{.skip @var{size} , @var{fill}}
3641 * Sleb128:: @code{.sleb128 @var{expressions}}
3642 * Space:: @code{.space @var{size} , @var{fill}}
3644 * Stab:: @code{.stabd, .stabn, .stabs}
3647 * String:: @code{.string "@var{str}"}
3648 * Struct:: @code{.struct @var{expression}}
3650 * SubSection:: @code{.subsection}
3651 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3655 * Tag:: @code{.tag @var{structname}}
3658 * Text:: @code{.text @var{subsection}}
3659 * Title:: @code{.title "@var{heading}"}
3660 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3661 * Uleb128:: @code{.uleb128 @var{expressions}}
3663 * Val:: @code{.val @var{addr}}
3667 * Version:: @code{.version "@var{string}"}
3668 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3669 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3670 * Weak:: @code{.weak @var{names}}
3673 * Word:: @code{.word @var{expressions}}
3674 * Deprecated:: Deprecated Directives
3678 @section @code{.abort}
3680 @cindex @code{abort} directive
3681 @cindex stopping the assembly
3682 This directive stops the assembly immediately. It is for
3683 compatibility with other assemblers. The original idea was that the
3684 assembly language source would be piped into the assembler. If the sender
3685 of the source quit, it could use this directive tells @command{@value{AS}} to
3686 quit also. One day @code{.abort} will not be supported.
3690 @section @code{.ABORT}
3692 @cindex @code{ABORT} directive
3693 When producing COFF output, @command{@value{AS}} accepts this directive as a
3694 synonym for @samp{.abort}.
3697 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3703 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3705 @cindex padding the location counter
3706 @cindex @code{align} directive
3707 Pad the location counter (in the current subsection) to a particular storage
3708 boundary. The first expression (which must be absolute) is the alignment
3709 required, as described below.
3711 The second expression (also absolute) gives the fill value to be stored in the
3712 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3713 padding bytes are normally zero. However, on some systems, if the section is
3714 marked as containing code and the fill value is omitted, the space is filled
3715 with no-op instructions.
3717 The third expression is also absolute, and is also optional. If it is present,
3718 it is the maximum number of bytes that should be skipped by this alignment
3719 directive. If doing the alignment would require skipping more bytes than the
3720 specified maximum, then the alignment is not done at all. You can omit the
3721 fill value (the second argument) entirely by simply using two commas after the
3722 required alignment; this can be useful if you want the alignment to be filled
3723 with no-op instructions when appropriate.
3725 The way the required alignment is specified varies from system to system.
3726 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3728 the first expression is the
3729 alignment request in bytes. For example @samp{.align 8} advances
3730 the location counter until it is a multiple of 8. If the location counter
3731 is already a multiple of 8, no change is needed.
3733 For other systems, including the i386 using a.out format, and the arm and
3734 strongarm, it is the
3735 number of low-order zero bits the location counter must have after
3736 advancement. For example @samp{.align 3} advances the location
3737 counter until it a multiple of 8. If the location counter is already a
3738 multiple of 8, no change is needed.
3740 This inconsistency is due to the different behaviors of the various
3741 native assemblers for these systems which GAS must emulate.
3742 GAS also provides @code{.balign} and @code{.p2align} directives,
3743 described later, which have a consistent behavior across all
3744 architectures (but are specific to GAS).
3747 @section @code{.ascii "@var{string}"}@dots{}
3749 @cindex @code{ascii} directive
3750 @cindex string literals
3751 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3752 separated by commas. It assembles each string (with no automatic
3753 trailing zero byte) into consecutive addresses.
3756 @section @code{.asciz "@var{string}"}@dots{}
3758 @cindex @code{asciz} directive
3759 @cindex zero-terminated strings
3760 @cindex null-terminated strings
3761 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3762 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3765 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3767 @cindex padding the location counter given number of bytes
3768 @cindex @code{balign} directive
3769 Pad the location counter (in the current subsection) to a particular
3770 storage boundary. The first expression (which must be absolute) is the
3771 alignment request in bytes. For example @samp{.balign 8} advances
3772 the location counter until it is a multiple of 8. If the location counter
3773 is already a multiple of 8, no change is needed.
3775 The second expression (also absolute) gives the fill value to be stored in the
3776 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3777 padding bytes are normally zero. However, on some systems, if the section is
3778 marked as containing code and the fill value is omitted, the space is filled
3779 with no-op instructions.
3781 The third expression is also absolute, and is also optional. If it is present,
3782 it is the maximum number of bytes that should be skipped by this alignment
3783 directive. If doing the alignment would require skipping more bytes than the
3784 specified maximum, then the alignment is not done at all. You can omit the
3785 fill value (the second argument) entirely by simply using two commas after the
3786 required alignment; this can be useful if you want the alignment to be filled
3787 with no-op instructions when appropriate.
3789 @cindex @code{balignw} directive
3790 @cindex @code{balignl} directive
3791 The @code{.balignw} and @code{.balignl} directives are variants of the
3792 @code{.balign} directive. The @code{.balignw} directive treats the fill
3793 pattern as a two byte word value. The @code{.balignl} directives treats the
3794 fill pattern as a four byte longword value. For example, @code{.balignw
3795 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3796 filled in with the value 0x368d (the exact placement of the bytes depends upon
3797 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3801 @section @code{.byte @var{expressions}}
3803 @cindex @code{byte} directive
3804 @cindex integers, one byte
3805 @code{.byte} expects zero or more expressions, separated by commas.
3806 Each expression is assembled into the next byte.
3809 @section @code{.comm @var{symbol} , @var{length} }
3811 @cindex @code{comm} directive
3812 @cindex symbol, common
3813 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3814 common symbol in one object file may be merged with a defined or common symbol
3815 of the same name in another object file. If @code{@value{LD}} does not see a
3816 definition for the symbol--just one or more common symbols--then it will
3817 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3818 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3819 the same name, and they do not all have the same size, it will allocate space
3820 using the largest size.
3823 When using ELF, the @code{.comm} directive takes an optional third argument.
3824 This is the desired alignment of the symbol, specified as a byte boundary (for
3825 example, an alignment of 16 means that the least significant 4 bits of the
3826 address should be zero). The alignment must be an absolute expression, and it
3827 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3828 for the common symbol, it will use the alignment when placing the symbol. If
3829 no alignment is specified, @command{@value{AS}} will set the alignment to the
3830 largest power of two less than or equal to the size of the symbol, up to a
3835 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3836 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3840 @section @code{.data @var{subsection}}
3842 @cindex @code{data} directive
3843 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3844 end of the data subsection numbered @var{subsection} (which is an
3845 absolute expression). If @var{subsection} is omitted, it defaults
3850 @section @code{.def @var{name}}
3852 @cindex @code{def} directive
3853 @cindex COFF symbols, debugging
3854 @cindex debugging COFF symbols
3855 Begin defining debugging information for a symbol @var{name}; the
3856 definition extends until the @code{.endef} directive is encountered.
3859 This directive is only observed when @command{@value{AS}} is configured for COFF
3860 format output; when producing @code{b.out}, @samp{.def} is recognized,
3867 @section @code{.desc @var{symbol}, @var{abs-expression}}
3869 @cindex @code{desc} directive
3870 @cindex COFF symbol descriptor
3871 @cindex symbol descriptor, COFF
3872 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3873 to the low 16 bits of an absolute expression.
3876 The @samp{.desc} directive is not available when @command{@value{AS}} is
3877 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3878 object format. For the sake of compatibility, @command{@value{AS}} accepts
3879 it, but produces no output, when configured for COFF.
3885 @section @code{.dim}
3887 @cindex @code{dim} directive
3888 @cindex COFF auxiliary symbol information
3889 @cindex auxiliary symbol information, COFF
3890 This directive is generated by compilers to include auxiliary debugging
3891 information in the symbol table. It is only permitted inside
3892 @code{.def}/@code{.endef} pairs.
3895 @samp{.dim} is only meaningful when generating COFF format output; when
3896 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3902 @section @code{.double @var{flonums}}
3904 @cindex @code{double} directive
3905 @cindex floating point numbers (double)
3906 @code{.double} expects zero or more flonums, separated by commas. It
3907 assembles floating point numbers.
3909 The exact kind of floating point numbers emitted depends on how
3910 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3914 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3915 in @sc{ieee} format.
3920 @section @code{.eject}
3922 @cindex @code{eject} directive
3923 @cindex new page, in listings
3924 @cindex page, in listings
3925 @cindex listing control: new page
3926 Force a page break at this point, when generating assembly listings.
3929 @section @code{.else}
3931 @cindex @code{else} directive
3932 @code{.else} is part of the @command{@value{AS}} support for conditional
3933 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3934 of code to be assembled if the condition for the preceding @code{.if}
3938 @section @code{.elseif}
3940 @cindex @code{elseif} directive
3941 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3942 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3943 @code{.if} block that would otherwise fill the entire @code{.else} section.
3946 @section @code{.end}
3948 @cindex @code{end} directive
3949 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3950 process anything in the file past the @code{.end} directive.
3954 @section @code{.endef}
3956 @cindex @code{endef} directive
3957 This directive flags the end of a symbol definition begun with
3961 @samp{.endef} is only meaningful when generating COFF format output; if
3962 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3963 directive but ignores it.
3968 @section @code{.endfunc}
3969 @cindex @code{endfunc} directive
3970 @code{.endfunc} marks the end of a function specified with @code{.func}.
3973 @section @code{.endif}
3975 @cindex @code{endif} directive
3976 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3977 it marks the end of a block of code that is only assembled
3978 conditionally. @xref{If,,@code{.if}}.
3981 @section @code{.equ @var{symbol}, @var{expression}}
3983 @cindex @code{equ} directive
3984 @cindex assigning values to symbols
3985 @cindex symbols, assigning values to
3986 This directive sets the value of @var{symbol} to @var{expression}.
3987 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3990 The syntax for @code{equ} on the HPPA is
3991 @samp{@var{symbol} .equ @var{expression}}.
3995 @section @code{.equiv @var{symbol}, @var{expression}}
3996 @cindex @code{equiv} directive
3997 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3998 the assembler will signal an error if @var{symbol} is already defined.
4000 Except for the contents of the error message, this is roughly equivalent to
4009 @section @code{.err}
4010 @cindex @code{err} directive
4011 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4012 message and, unless the @option{-Z} option was used, it will not generate an
4013 object file. This can be used to signal error an conditionally compiled code.
4016 @section @code{.exitm}
4017 Exit early from the current macro definition. @xref{Macro}.
4020 @section @code{.extern}
4022 @cindex @code{extern} directive
4023 @code{.extern} is accepted in the source program---for compatibility
4024 with other assemblers---but it is ignored. @command{@value{AS}} treats
4025 all undefined symbols as external.
4028 @section @code{.fail @var{expression}}
4030 @cindex @code{fail} directive
4031 Generates an error or a warning. If the value of the @var{expression} is 500
4032 or more, @command{@value{AS}} will print a warning message. If the value is less
4033 than 500, @command{@value{AS}} will print an error message. The message will
4034 include the value of @var{expression}. This can occasionally be useful inside
4035 complex nested macros or conditional assembly.
4037 @ifclear no-file-dir
4039 @section @code{.file @var{string}}
4041 @cindex @code{file} directive
4042 @cindex logical file name
4043 @cindex file name, logical
4044 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4045 file. @var{string} is the new file name. In general, the filename is
4046 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4047 to specify an empty file name, you must give the quotes--@code{""}. This
4048 statement may go away in future: it is only recognized to be compatible with
4049 old @command{@value{AS}} programs.
4051 In some configurations of @command{@value{AS}}, @code{.file} has already been
4052 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4057 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4059 @cindex @code{fill} directive
4060 @cindex writing patterns in memory
4061 @cindex patterns, writing in memory
4062 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4063 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4064 may be zero or more. @var{Size} may be zero or more, but if it is
4065 more than 8, then it is deemed to have the value 8, compatible with
4066 other people's assemblers. The contents of each @var{repeat} bytes
4067 is taken from an 8-byte number. The highest order 4 bytes are
4068 zero. The lowest order 4 bytes are @var{value} rendered in the
4069 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4070 Each @var{size} bytes in a repetition is taken from the lowest order
4071 @var{size} bytes of this number. Again, this bizarre behavior is
4072 compatible with other people's assemblers.
4074 @var{size} and @var{value} are optional.
4075 If the second comma and @var{value} are absent, @var{value} is
4076 assumed zero. If the first comma and following tokens are absent,
4077 @var{size} is assumed to be 1.
4080 @section @code{.float @var{flonums}}
4082 @cindex floating point numbers (single)
4083 @cindex @code{float} directive
4084 This directive assembles zero or more flonums, separated by commas. It
4085 has the same effect as @code{.single}.
4087 The exact kind of floating point numbers emitted depends on how
4088 @command{@value{AS}} is configured.
4089 @xref{Machine Dependencies}.
4093 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4094 in @sc{ieee} format.
4099 @section @code{.func @var{name}[,@var{label}]}
4100 @cindex @code{func} directive
4101 @code{.func} emits debugging information to denote function @var{name}, and
4102 is ignored unless the file is assembled with debugging enabled.
4103 Only @samp{--gstabs} is currently supported.
4104 @var{label} is the entry point of the function and if omitted @var{name}
4105 prepended with the @samp{leading char} is used.
4106 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4107 All functions are currently defined to have @code{void} return type.
4108 The function must be terminated with @code{.endfunc}.
4111 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4113 @cindex @code{global} directive
4114 @cindex symbol, making visible to linker
4115 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4116 @var{symbol} in your partial program, its value is made available to
4117 other partial programs that are linked with it. Otherwise,
4118 @var{symbol} takes its attributes from a symbol of the same name
4119 from another file linked into the same program.
4121 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4122 compatibility with other assemblers.
4125 On the HPPA, @code{.global} is not always enough to make it accessible to other
4126 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4127 @xref{HPPA Directives,, HPPA Assembler Directives}.
4132 @section @code{.hidden @var{names}}
4134 @cindex @code{.hidden} directive
4136 This one of the ELF visibility directives. The other two are
4137 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4138 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4140 This directive overrides the named symbols default visibility (which is set by
4141 their binding: local, global or weak). The directive sets the visibility to
4142 @code{hidden} which means that the symbols are not visible to other components.
4143 Such symbols are always considered to be @code{protected} as well.
4147 @section @code{.hword @var{expressions}}
4149 @cindex @code{hword} directive
4150 @cindex integers, 16-bit
4151 @cindex numbers, 16-bit
4152 @cindex sixteen bit integers
4153 This expects zero or more @var{expressions}, and emits
4154 a 16 bit number for each.
4157 This directive is a synonym for @samp{.short}; depending on the target
4158 architecture, it may also be a synonym for @samp{.word}.
4162 This directive is a synonym for @samp{.short}.
4165 This directive is a synonym for both @samp{.short} and @samp{.word}.
4170 @section @code{.ident}
4172 @cindex @code{ident} directive
4173 This directive is used by some assemblers to place tags in object files.
4174 @command{@value{AS}} simply accepts the directive for source-file
4175 compatibility with such assemblers, but does not actually emit anything
4179 @section @code{.if @var{absolute expression}}
4181 @cindex conditional assembly
4182 @cindex @code{if} directive
4183 @code{.if} marks the beginning of a section of code which is only
4184 considered part of the source program being assembled if the argument
4185 (which must be an @var{absolute expression}) is non-zero. The end of
4186 the conditional section of code must be marked by @code{.endif}
4187 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4188 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4189 If you have several conditions to check, @code{.elseif} may be used to avoid
4190 nesting blocks if/else within each subsequent @code{.else} block.
4192 The following variants of @code{.if} are also supported:
4194 @cindex @code{ifdef} directive
4195 @item .ifdef @var{symbol}
4196 Assembles the following section of code if the specified @var{symbol}
4199 @cindex @code{ifc} directive
4200 @item .ifc @var{string1},@var{string2}
4201 Assembles the following section of code if the two strings are the same. The
4202 strings may be optionally quoted with single quotes. If they are not quoted,
4203 the first string stops at the first comma, and the second string stops at the
4204 end of the line. Strings which contain whitespace should be quoted. The
4205 string comparison is case sensitive.
4207 @cindex @code{ifeq} directive
4208 @item .ifeq @var{absolute expression}
4209 Assembles the following section of code if the argument is zero.
4211 @cindex @code{ifeqs} directive
4212 @item .ifeqs @var{string1},@var{string2}
4213 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4215 @cindex @code{ifge} directive
4216 @item .ifge @var{absolute expression}
4217 Assembles the following section of code if the argument is greater than or
4220 @cindex @code{ifgt} directive
4221 @item .ifgt @var{absolute expression}
4222 Assembles the following section of code if the argument is greater than zero.
4224 @cindex @code{ifle} directive
4225 @item .ifle @var{absolute expression}
4226 Assembles the following section of code if the argument is less than or equal
4229 @cindex @code{iflt} directive
4230 @item .iflt @var{absolute expression}
4231 Assembles the following section of code if the argument is less than zero.
4233 @cindex @code{ifnc} directive
4234 @item .ifnc @var{string1},@var{string2}.
4235 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4236 following section of code if the two strings are not the same.
4238 @cindex @code{ifndef} directive
4239 @cindex @code{ifnotdef} directive
4240 @item .ifndef @var{symbol}
4241 @itemx .ifnotdef @var{symbol}
4242 Assembles the following section of code if the specified @var{symbol}
4243 has not been defined. Both spelling variants are equivalent.
4245 @cindex @code{ifne} directive
4246 @item .ifne @var{absolute expression}
4247 Assembles the following section of code if the argument is not equal to zero
4248 (in other words, this is equivalent to @code{.if}).
4250 @cindex @code{ifnes} directive
4251 @item .ifnes @var{string1},@var{string2}
4252 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4253 following section of code if the two strings are not the same.
4257 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4259 @cindex @code{incbin} directive
4260 @cindex binary files, including
4261 The @code{incbin} directive includes @var{file} verbatim at the current
4262 location. You can control the search paths used with the @samp{-I} command-line
4263 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4266 The @var{skip} argument skips a number of bytes from the start of the
4267 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4268 read. Note that the data is not aligned in any way, so it is the user's
4269 responsibility to make sure that proper alignment is provided both before and
4270 after the @code{incbin} directive.
4273 @section @code{.include "@var{file}"}
4275 @cindex @code{include} directive
4276 @cindex supporting files, including
4277 @cindex files, including
4278 This directive provides a way to include supporting files at specified
4279 points in your source program. The code from @var{file} is assembled as
4280 if it followed the point of the @code{.include}; when the end of the
4281 included file is reached, assembly of the original file continues. You
4282 can control the search paths used with the @samp{-I} command-line option
4283 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4287 @section @code{.int @var{expressions}}
4289 @cindex @code{int} directive
4290 @cindex integers, 32-bit
4291 Expect zero or more @var{expressions}, of any section, separated by commas.
4292 For each expression, emit a number that, at run time, is the value of that
4293 expression. The byte order and bit size of the number depends on what kind
4294 of target the assembly is for.
4298 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4299 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4306 @section @code{.internal @var{names}}
4308 @cindex @code{.internal} directive
4310 This one of the ELF visibility directives. The other two are
4311 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4312 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4314 This directive overrides the named symbols default visibility (which is set by
4315 their binding: local, global or weak). The directive sets the visibility to
4316 @code{internal} which means that the symbols are considered to be @code{hidden}
4317 (ie not visible to other components), and that some extra, processor specific
4318 processing must also be performed upon the symbols as well.
4322 @section @code{.irp @var{symbol},@var{values}}@dots{}
4324 @cindex @code{irp} directive
4325 Evaluate a sequence of statements assigning different values to @var{symbol}.
4326 The sequence of statements starts at the @code{.irp} directive, and is
4327 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4328 set to @var{value}, and the sequence of statements is assembled. If no
4329 @var{value} is listed, the sequence of statements is assembled once, with
4330 @var{symbol} set to the null string. To refer to @var{symbol} within the
4331 sequence of statements, use @var{\symbol}.
4333 For example, assembling
4341 is equivalent to assembling
4350 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4352 @cindex @code{irpc} directive
4353 Evaluate a sequence of statements assigning different values to @var{symbol}.
4354 The sequence of statements starts at the @code{.irpc} directive, and is
4355 terminated by an @code{.endr} directive. For each character in @var{value},
4356 @var{symbol} is set to the character, and the sequence of statements is
4357 assembled. If no @var{value} is listed, the sequence of statements is
4358 assembled once, with @var{symbol} set to the null string. To refer to
4359 @var{symbol} within the sequence of statements, use @var{\symbol}.
4361 For example, assembling
4369 is equivalent to assembling
4378 @section @code{.lcomm @var{symbol} , @var{length}}
4380 @cindex @code{lcomm} directive
4381 @cindex local common symbols
4382 @cindex symbols, local common
4383 Reserve @var{length} (an absolute expression) bytes for a local common
4384 denoted by @var{symbol}. The section and value of @var{symbol} are
4385 those of the new local common. The addresses are allocated in the bss
4386 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4387 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4388 not visible to @code{@value{LD}}.
4391 Some targets permit a third argument to be used with @code{.lcomm}. This
4392 argument specifies the desired alignment of the symbol in the bss section.
4396 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4397 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4401 @section @code{.lflags}
4403 @cindex @code{lflags} directive (ignored)
4404 @command{@value{AS}} accepts this directive, for compatibility with other
4405 assemblers, but ignores it.
4407 @ifclear no-line-dir
4409 @section @code{.line @var{line-number}}
4411 @cindex @code{line} directive
4415 @section @code{.ln @var{line-number}}
4417 @cindex @code{ln} directive
4419 @cindex logical line number
4421 Change the logical line number. @var{line-number} must be an absolute
4422 expression. The next line has that logical line number. Therefore any other
4423 statements on the current line (after a statement separator character) are
4424 reported as on logical line number @var{line-number} @minus{} 1. One day
4425 @command{@value{AS}} will no longer support this directive: it is recognized only
4426 for compatibility with existing assembler programs.
4430 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4431 not available; use the synonym @code{.ln} in that context.
4436 @ifclear no-line-dir
4437 Even though this is a directive associated with the @code{a.out} or
4438 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4439 when producing COFF output, and treats @samp{.line} as though it
4440 were the COFF @samp{.ln} @emph{if} it is found outside a
4441 @code{.def}/@code{.endef} pair.
4443 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4444 used by compilers to generate auxiliary symbol information for
4449 @section @code{.linkonce [@var{type}]}
4451 @cindex @code{linkonce} directive
4452 @cindex common sections
4453 Mark the current section so that the linker only includes a single copy of it.
4454 This may be used to include the same section in several different object files,
4455 but ensure that the linker will only include it once in the final output file.
4456 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4457 Duplicate sections are detected based on the section name, so it should be
4460 This directive is only supported by a few object file formats; as of this
4461 writing, the only object file format which supports it is the Portable
4462 Executable format used on Windows NT.
4464 The @var{type} argument is optional. If specified, it must be one of the
4465 following strings. For example:
4469 Not all types may be supported on all object file formats.
4473 Silently discard duplicate sections. This is the default.
4476 Warn if there are duplicate sections, but still keep only one copy.
4479 Warn if any of the duplicates have different sizes.
4482 Warn if any of the duplicates do not have exactly the same contents.
4486 @section @code{.ln @var{line-number}}
4488 @cindex @code{ln} directive
4489 @ifclear no-line-dir
4490 @samp{.ln} is a synonym for @samp{.line}.
4493 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4494 must be an absolute expression. The next line has that logical
4495 line number, so any other statements on the current line (after a
4496 statement separator character @code{;}) are reported as on logical
4497 line number @var{line-number} @minus{} 1.
4500 This directive is accepted, but ignored, when @command{@value{AS}} is
4501 configured for @code{b.out}; its effect is only associated with COFF
4507 @section @code{.mri @var{val}}
4509 @cindex @code{mri} directive
4510 @cindex MRI mode, temporarily
4511 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4512 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4513 affects code assembled until the next @code{.mri} directive, or until the end
4514 of the file. @xref{M, MRI mode, MRI mode}.
4517 @section @code{.list}
4519 @cindex @code{list} directive
4520 @cindex listing control, turning on
4521 Control (in conjunction with the @code{.nolist} directive) whether or
4522 not assembly listings are generated. These two directives maintain an
4523 internal counter (which is zero initially). @code{.list} increments the
4524 counter, and @code{.nolist} decrements it. Assembly listings are
4525 generated whenever the counter is greater than zero.
4527 By default, listings are disabled. When you enable them (with the
4528 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4529 the initial value of the listing counter is one.
4532 @section @code{.long @var{expressions}}
4534 @cindex @code{long} directive
4535 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4538 @c no one seems to know what this is for or whether this description is
4539 @c what it really ought to do
4541 @section @code{.lsym @var{symbol}, @var{expression}}
4543 @cindex @code{lsym} directive
4544 @cindex symbol, not referenced in assembly
4545 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4546 the hash table, ensuring it cannot be referenced by name during the
4547 rest of the assembly. This sets the attributes of the symbol to be
4548 the same as the expression value:
4550 @var{other} = @var{descriptor} = 0
4551 @var{type} = @r{(section of @var{expression})}
4552 @var{value} = @var{expression}
4555 The new symbol is not flagged as external.
4559 @section @code{.macro}
4562 The commands @code{.macro} and @code{.endm} allow you to define macros that
4563 generate assembly output. For example, this definition specifies a macro
4564 @code{sum} that puts a sequence of numbers into memory:
4567 .macro sum from=0, to=5
4576 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4588 @item .macro @var{macname}
4589 @itemx .macro @var{macname} @var{macargs} @dots{}
4590 @cindex @code{macro} directive
4591 Begin the definition of a macro called @var{macname}. If your macro
4592 definition requires arguments, specify their names after the macro name,
4593 separated by commas or spaces. You can supply a default value for any
4594 macro argument by following the name with @samp{=@var{deflt}}. For
4595 example, these are all valid @code{.macro} statements:
4599 Begin the definition of a macro called @code{comm}, which takes no
4602 @item .macro plus1 p, p1
4603 @itemx .macro plus1 p p1
4604 Either statement begins the definition of a macro called @code{plus1},
4605 which takes two arguments; within the macro definition, write
4606 @samp{\p} or @samp{\p1} to evaluate the arguments.
4608 @item .macro reserve_str p1=0 p2
4609 Begin the definition of a macro called @code{reserve_str}, with two
4610 arguments. The first argument has a default value, but not the second.
4611 After the definition is complete, you can call the macro either as
4612 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4613 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4614 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4615 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4618 When you call a macro, you can specify the argument values either by
4619 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4620 @samp{sum to=17, from=9}.
4623 @cindex @code{endm} directive
4624 Mark the end of a macro definition.
4627 @cindex @code{exitm} directive
4628 Exit early from the current macro definition.
4630 @cindex number of macros executed
4631 @cindex macros, count executed
4633 @command{@value{AS}} maintains a counter of how many macros it has
4634 executed in this pseudo-variable; you can copy that number to your
4635 output with @samp{\@@}, but @emph{only within a macro definition}.
4638 @item LOCAL @var{name} [ , @dots{} ]
4639 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4640 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4641 Alternate macro syntax}.
4643 Generate a string replacement for each of the @var{name} arguments, and
4644 replace any instances of @var{name} in each macro expansion. The
4645 replacement string is unique in the assembly, and different for each
4646 separate macro expansion. @code{LOCAL} allows you to write macros that
4647 define symbols, without fear of conflict between separate macro expansions.
4652 @section @code{.nolist}
4654 @cindex @code{nolist} directive
4655 @cindex listing control, turning off
4656 Control (in conjunction with the @code{.list} directive) whether or
4657 not assembly listings are generated. These two directives maintain an
4658 internal counter (which is zero initially). @code{.list} increments the
4659 counter, and @code{.nolist} decrements it. Assembly listings are
4660 generated whenever the counter is greater than zero.
4663 @section @code{.octa @var{bignums}}
4665 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4666 @cindex @code{octa} directive
4667 @cindex integer, 16-byte
4668 @cindex sixteen byte integer
4669 This directive expects zero or more bignums, separated by commas. For each
4670 bignum, it emits a 16-byte integer.
4672 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4673 hence @emph{octa}-word for 16 bytes.
4676 @section @code{.org @var{new-lc} , @var{fill}}
4678 @cindex @code{org} directive
4679 @cindex location counter, advancing
4680 @cindex advancing location counter
4681 @cindex current address, advancing
4682 Advance the location counter of the current section to
4683 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4684 expression with the same section as the current subsection. That is,
4685 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4686 wrong section, the @code{.org} directive is ignored. To be compatible
4687 with former assemblers, if the section of @var{new-lc} is absolute,
4688 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4689 is the same as the current subsection.
4691 @code{.org} may only increase the location counter, or leave it
4692 unchanged; you cannot use @code{.org} to move the location counter
4695 @c double negative used below "not undefined" because this is a specific
4696 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4697 @c section. doc@cygnus.com 18feb91
4698 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4699 may not be undefined. If you really detest this restriction we eagerly await
4700 a chance to share your improved assembler.
4702 Beware that the origin is relative to the start of the section, not
4703 to the start of the subsection. This is compatible with other
4704 people's assemblers.
4706 When the location counter (of the current subsection) is advanced, the
4707 intervening bytes are filled with @var{fill} which should be an
4708 absolute expression. If the comma and @var{fill} are omitted,
4709 @var{fill} defaults to zero.
4712 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4714 @cindex padding the location counter given a power of two
4715 @cindex @code{p2align} directive
4716 Pad the location counter (in the current subsection) to a particular
4717 storage boundary. The first expression (which must be absolute) is the
4718 number of low-order zero bits the location counter must have after
4719 advancement. For example @samp{.p2align 3} advances the location
4720 counter until it a multiple of 8. If the location counter is already a
4721 multiple of 8, no change is needed.
4723 The second expression (also absolute) gives the fill value to be stored in the
4724 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4725 padding bytes are normally zero. However, on some systems, if the section is
4726 marked as containing code and the fill value is omitted, the space is filled
4727 with no-op instructions.
4729 The third expression is also absolute, and is also optional. If it is present,
4730 it is the maximum number of bytes that should be skipped by this alignment
4731 directive. If doing the alignment would require skipping more bytes than the
4732 specified maximum, then the alignment is not done at all. You can omit the
4733 fill value (the second argument) entirely by simply using two commas after the
4734 required alignment; this can be useful if you want the alignment to be filled
4735 with no-op instructions when appropriate.
4737 @cindex @code{p2alignw} directive
4738 @cindex @code{p2alignl} directive
4739 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4740 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4741 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4742 fill pattern as a four byte longword value. For example, @code{.p2alignw
4743 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4744 filled in with the value 0x368d (the exact placement of the bytes depends upon
4745 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4750 @section @code{.previous}
4752 @cindex @code{.previous} directive
4753 @cindex Section Stack
4754 This is one of the ELF section stack manipulation directives. The others are
4755 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4756 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4757 (@pxref{PopSection}).
4759 This directive swaps the current section (and subsection) with most recently
4760 referenced section (and subsection) prior to this one. Multiple
4761 @code{.previous} directives in a row will flip between two sections (and their
4764 In terms of the section stack, this directive swaps the current section with
4765 the top section on the section stack.
4770 @section @code{.popsection}
4772 @cindex @code{.popsection} directive
4773 @cindex Section Stack
4774 This is one of the ELF section stack manipulation directives. The others are
4775 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4776 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4779 This directive replaces the current section (and subsection) with the top
4780 section (and subsection) on the section stack. This section is popped off the
4785 @section @code{.print @var{string}}
4787 @cindex @code{print} directive
4788 @command{@value{AS}} will print @var{string} on the standard output during
4789 assembly. You must put @var{string} in double quotes.
4793 @section @code{.protected @var{names}}
4795 @cindex @code{.protected} directive
4797 This one of the ELF visibility directives. The other two are
4798 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4800 This directive overrides the named symbols default visibility (which is set by
4801 their binding: local, global or weak). The directive sets the visibility to
4802 @code{protected} which means that any references to the symbols from within the
4803 components that defines them must be resolved to the definition in that
4804 component, even if a definition in another component would normally preempt
4809 @section @code{.psize @var{lines} , @var{columns}}
4811 @cindex @code{psize} directive
4812 @cindex listing control: paper size
4813 @cindex paper size, for listings
4814 Use this directive to declare the number of lines---and, optionally, the
4815 number of columns---to use for each page, when generating listings.
4817 If you do not use @code{.psize}, listings use a default line-count
4818 of 60. You may omit the comma and @var{columns} specification; the
4819 default width is 200 columns.
4821 @command{@value{AS}} generates formfeeds whenever the specified number of
4822 lines is exceeded (or whenever you explicitly request one, using
4825 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4826 those explicitly specified with @code{.eject}.
4829 @section @code{.purgem @var{name}}
4831 @cindex @code{purgem} directive
4832 Undefine the macro @var{name}, so that later uses of the string will not be
4833 expanded. @xref{Macro}.
4837 @section @code{.pushsection @var{name} , @var{subsection}}
4839 @cindex @code{.pushsection} directive
4840 @cindex Section Stack
4841 This is one of the ELF section stack manipulation directives. The others are
4842 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4843 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4846 This directive is a synonym for @code{.section}. It pushes the current section
4847 (and subsection) onto the top of the section stack, and then replaces the
4848 current section and subsection with @code{name} and @code{subsection}.
4852 @section @code{.quad @var{bignums}}
4854 @cindex @code{quad} directive
4855 @code{.quad} expects zero or more bignums, separated by commas. For
4856 each bignum, it emits
4858 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4859 warning message; and just takes the lowest order 8 bytes of the bignum.
4860 @cindex eight-byte integer
4861 @cindex integer, 8-byte
4863 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4864 hence @emph{quad}-word for 8 bytes.
4867 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4868 warning message; and just takes the lowest order 16 bytes of the bignum.
4869 @cindex sixteen-byte integer
4870 @cindex integer, 16-byte
4874 @section @code{.rept @var{count}}
4876 @cindex @code{rept} directive
4877 Repeat the sequence of lines between the @code{.rept} directive and the next
4878 @code{.endr} directive @var{count} times.
4880 For example, assembling
4888 is equivalent to assembling
4897 @section @code{.sbttl "@var{subheading}"}
4899 @cindex @code{sbttl} directive
4900 @cindex subtitles for listings
4901 @cindex listing control: subtitle
4902 Use @var{subheading} as the title (third line, immediately after the
4903 title line) when generating assembly listings.
4905 This directive affects subsequent pages, as well as the current page if
4906 it appears within ten lines of the top of a page.
4910 @section @code{.scl @var{class}}
4912 @cindex @code{scl} directive
4913 @cindex symbol storage class (COFF)
4914 @cindex COFF symbol storage class
4915 Set the storage-class value for a symbol. This directive may only be
4916 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4917 whether a symbol is static or external, or it may record further
4918 symbolic debugging information.
4921 The @samp{.scl} directive is primarily associated with COFF output; when
4922 configured to generate @code{b.out} output format, @command{@value{AS}}
4923 accepts this directive but ignores it.
4928 @section @code{.section @var{name}} (COFF version)
4930 @cindex @code{section} directive
4931 @cindex named section
4932 Use the @code{.section} directive to assemble the following code into a section
4935 This directive is only supported for targets that actually support arbitrarily
4936 named sections; on @code{a.out} targets, for example, it is not accepted, even
4937 with a standard @code{a.out} section name.
4939 For COFF targets, the @code{.section} directive is used in one of the following
4943 .section @var{name}[, "@var{flags}"]
4944 .section @var{name}[, @var{subsegment}]
4947 If the optional argument is quoted, it is taken as flags to use for the
4948 section. Each flag is a single character. The following flags are recognized:
4951 bss section (uninitialized data)
4953 section is not loaded
4963 shared section (meaningful for PE targets)
4966 If no flags are specified, the default flags depend upon the section name. If
4967 the section name is not recognized, the default will be for the section to be
4968 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4969 from the section, rather than adding them, so if they are used on their own it
4970 will be as if no flags had been specified at all.
4972 If the optional argument to the @code{.section} directive is not quoted, it is
4973 taken as a subsegment number (@pxref{Sub-Sections}).
4976 @section @code{.section @var{name}} (ELF version)
4978 @cindex @code{section} directive
4979 @cindex named section
4981 @cindex Section Stack
4982 This is one of the ELF section stack manipulation directives. The others are
4983 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4984 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4985 @code{.previous} (@pxref{Previous}).
4988 For ELF targets, the @code{.section} directive is used like this:
4991 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
4994 The optional @var{flags} argument is a quoted string which may contain any
4995 combination of the following characters:
4998 section is allocatable
5002 section is executable
5004 section is mergeable
5006 section contains zero terminated strings
5009 The optional @var{type} argument may contain one of the following constants:
5012 section contains data
5014 section does not contain data (i.e., section only occupies space)
5017 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5018 as well as @var{entsize} argument. Sections with @code{M} flag but not
5019 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5020 long. Sections with both @code{M} and @code{S} must contain zero terminated
5021 strings where each character is @var{entsize} bytes long. The linker may remove
5022 duplicates within sections with the same name, same entity size and same flags.
5024 If no flags are specified, the default flags depend upon the section name. If
5025 the section name is not recognized, the default will be for the section to have
5026 none of the above flags: it will not be allocated in memory, nor writable, nor
5027 executable. The section will contain data.
5029 For ELF targets, the assembler supports another type of @code{.section}
5030 directive for compatibility with the Solaris assembler:
5033 .section "@var{name}"[, @var{flags}...]
5036 Note that the section name is quoted. There may be a sequence of comma
5040 section is allocatable
5044 section is executable
5047 This directive replaces the current section and subsection. The replaced
5048 section and subsection are pushed onto the section stack. See the contents of
5049 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5050 how this directive and the other section stack directives work.
5053 @section @code{.set @var{symbol}, @var{expression}}
5055 @cindex @code{set} directive
5056 @cindex symbol value, setting
5057 Set the value of @var{symbol} to @var{expression}. This
5058 changes @var{symbol}'s value and type to conform to
5059 @var{expression}. If @var{symbol} was flagged as external, it remains
5060 flagged (@pxref{Symbol Attributes}).
5062 You may @code{.set} a symbol many times in the same assembly.
5064 If you @code{.set} a global symbol, the value stored in the object
5065 file is the last value stored into it.
5068 The syntax for @code{set} on the HPPA is
5069 @samp{@var{symbol} .set @var{expression}}.
5073 @section @code{.short @var{expressions}}
5075 @cindex @code{short} directive
5077 @code{.short} is normally the same as @samp{.word}.
5078 @xref{Word,,@code{.word}}.
5080 In some configurations, however, @code{.short} and @code{.word} generate
5081 numbers of different lengths; @pxref{Machine Dependencies}.
5085 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5088 This expects zero or more @var{expressions}, and emits
5089 a 16 bit number for each.
5094 @section @code{.single @var{flonums}}
5096 @cindex @code{single} directive
5097 @cindex floating point numbers (single)
5098 This directive assembles zero or more flonums, separated by commas. It
5099 has the same effect as @code{.float}.
5101 The exact kind of floating point numbers emitted depends on how
5102 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5106 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5107 numbers in @sc{ieee} format.
5112 @section @code{.size} (COFF version)
5114 @cindex @code{size} directive
5115 This directive is generated by compilers to include auxiliary debugging
5116 information in the symbol table. It is only permitted inside
5117 @code{.def}/@code{.endef} pairs.
5120 @samp{.size} is only meaningful when generating COFF format output; when
5121 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5125 @section @code{.size @var{name} , @var{expression}} (ELF version)
5126 @cindex @code{size} directive
5128 This directive is used to set the size associated with a symbol @var{name}.
5129 The size in bytes is computed from @var{expression} which can make use of label
5130 arithmetic. This directive is typically used to set the size of function
5134 @section @code{.sleb128 @var{expressions}}
5136 @cindex @code{sleb128} directive
5137 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5138 compact, variable length representation of numbers used by the DWARF
5139 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5141 @ifclear no-space-dir
5143 @section @code{.skip @var{size} , @var{fill}}
5145 @cindex @code{skip} directive
5146 @cindex filling memory
5147 This directive emits @var{size} bytes, each of value @var{fill}. Both
5148 @var{size} and @var{fill} are absolute expressions. If the comma and
5149 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5153 @section @code{.space @var{size} , @var{fill}}
5155 @cindex @code{space} directive
5156 @cindex filling memory
5157 This directive emits @var{size} bytes, each of value @var{fill}. Both
5158 @var{size} and @var{fill} are absolute expressions. If the comma
5159 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5164 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5165 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5166 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5167 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5176 @section @code{.space}
5177 @cindex @code{space} directive
5179 On the AMD 29K, this directive is ignored; it is accepted for
5180 compatibility with other AMD 29K assemblers.
5183 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5184 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5190 @section @code{.stabd, .stabn, .stabs}
5192 @cindex symbolic debuggers, information for
5193 @cindex @code{stab@var{x}} directives
5194 There are three directives that begin @samp{.stab}.
5195 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5196 The symbols are not entered in the @command{@value{AS}} hash table: they
5197 cannot be referenced elsewhere in the source file.
5198 Up to five fields are required:
5202 This is the symbol's name. It may contain any character except
5203 @samp{\000}, so is more general than ordinary symbol names. Some
5204 debuggers used to code arbitrarily complex structures into symbol names
5208 An absolute expression. The symbol's type is set to the low 8 bits of
5209 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5210 and debuggers choke on silly bit patterns.
5213 An absolute expression. The symbol's ``other'' attribute is set to the
5214 low 8 bits of this expression.
5217 An absolute expression. The symbol's descriptor is set to the low 16
5218 bits of this expression.
5221 An absolute expression which becomes the symbol's value.
5224 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5225 or @code{.stabs} statement, the symbol has probably already been created;
5226 you get a half-formed symbol in your object file. This is
5227 compatible with earlier assemblers!
5230 @cindex @code{stabd} directive
5231 @item .stabd @var{type} , @var{other} , @var{desc}
5233 The ``name'' of the symbol generated is not even an empty string.
5234 It is a null pointer, for compatibility. Older assemblers used a
5235 null pointer so they didn't waste space in object files with empty
5238 The symbol's value is set to the location counter,
5239 relocatably. When your program is linked, the value of this symbol
5240 is the address of the location counter when the @code{.stabd} was
5243 @cindex @code{stabn} directive
5244 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5245 The name of the symbol is set to the empty string @code{""}.
5247 @cindex @code{stabs} directive
5248 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5249 All five fields are specified.
5255 @section @code{.string} "@var{str}"
5257 @cindex string, copying to object file
5258 @cindex @code{string} directive
5260 Copy the characters in @var{str} to the object file. You may specify more than
5261 one string to copy, separated by commas. Unless otherwise specified for a
5262 particular machine, the assembler marks the end of each string with a 0 byte.
5263 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5266 @section @code{.struct @var{expression}}
5268 @cindex @code{struct} directive
5269 Switch to the absolute section, and set the section offset to @var{expression},
5270 which must be an absolute expression. You might use this as follows:
5279 This would define the symbol @code{field1} to have the value 0, the symbol
5280 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5281 value 8. Assembly would be left in the absolute section, and you would need to
5282 use a @code{.section} directive of some sort to change to some other section
5283 before further assembly.
5287 @section @code{.subsection @var{name}}
5289 @cindex @code{.subsection} directive
5290 @cindex Section Stack
5291 This is one of the ELF section stack manipulation directives. The others are
5292 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5293 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5296 This directive replaces the current subsection with @code{name}. The current
5297 section is not changed. The replaced subsection is put onto the section stack
5298 in place of the then current top of stack subsection.
5303 @section @code{.symver}
5304 @cindex @code{symver} directive
5305 @cindex symbol versioning
5306 @cindex versions of symbols
5307 Use the @code{.symver} directive to bind symbols to specific version nodes
5308 within a source file. This is only supported on ELF platforms, and is
5309 typically used when assembling files to be linked into a shared library.
5310 There are cases where it may make sense to use this in objects to be bound
5311 into an application itself so as to override a versioned symbol from a
5314 For ELF targets, the @code{.symver} directive can be used like this:
5316 .symver @var{name}, @var{name2@@nodename}
5318 If the symbol @var{name} is defined within the file
5319 being assembled, the @code{.symver} directive effectively creates a symbol
5320 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5321 just don't try and create a regular alias is that the @var{@@} character isn't
5322 permitted in symbol names. The @var{name2} part of the name is the actual name
5323 of the symbol by which it will be externally referenced. The name @var{name}
5324 itself is merely a name of convenience that is used so that it is possible to
5325 have definitions for multiple versions of a function within a single source
5326 file, and so that the compiler can unambiguously know which version of a
5327 function is being mentioned. The @var{nodename} portion of the alias should be
5328 the name of a node specified in the version script supplied to the linker when
5329 building a shared library. If you are attempting to override a versioned
5330 symbol from a shared library, then @var{nodename} should correspond to the
5331 nodename of the symbol you are trying to override.
5333 If the symbol @var{name} is not defined within the file being assembled, all
5334 references to @var{name} will be changed to @var{name2@@nodename}. If no
5335 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5338 Another usage of the @code{.symver} directive is:
5340 .symver @var{name}, @var{name2@@@@nodename}
5342 In this case, the symbol @var{name} must exist and be defined within
5343 the file being assembled. It is similar to @var{name2@@nodename}. The
5344 difference is @var{name2@@@@nodename} will also be used to resolve
5345 references to @var{name2} by the linker.
5347 The third usage of the @code{.symver} directive is:
5349 .symver @var{name}, @var{name2@@@@@@nodename}
5351 When @var{name} is not defined within the
5352 file being assembled, it is treated as @var{name2@@nodename}. When
5353 @var{name} is defined within the file being assembled, the symbol
5354 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5359 @section @code{.tag @var{structname}}
5361 @cindex COFF structure debugging
5362 @cindex structure debugging, COFF
5363 @cindex @code{tag} directive
5364 This directive is generated by compilers to include auxiliary debugging
5365 information in the symbol table. It is only permitted inside
5366 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5367 definitions in the symbol table with instances of those structures.
5370 @samp{.tag} is only used when generating COFF format output; when
5371 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5377 @section @code{.text @var{subsection}}
5379 @cindex @code{text} directive
5380 Tells @command{@value{AS}} to assemble the following statements onto the end of
5381 the text subsection numbered @var{subsection}, which is an absolute
5382 expression. If @var{subsection} is omitted, subsection number zero
5386 @section @code{.title "@var{heading}"}
5388 @cindex @code{title} directive
5389 @cindex listing control: title line
5390 Use @var{heading} as the title (second line, immediately after the
5391 source file name and pagenumber) when generating assembly listings.
5393 This directive affects subsequent pages, as well as the current page if
5394 it appears within ten lines of the top of a page.
5397 @section @code{.type @var{int}} (COFF version)
5399 @cindex COFF symbol type
5400 @cindex symbol type, COFF
5401 @cindex @code{type} directive
5402 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5403 records the integer @var{int} as the type attribute of a symbol table entry.
5406 @samp{.type} is associated only with COFF format output; when
5407 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5408 directive but ignores it.
5411 @section @code{.type @var{name} , @var{type description}} (ELF version)
5413 @cindex ELF symbol type
5414 @cindex symbol type, ELF
5415 @cindex @code{type} directive
5416 This directive is used to set the type of symbol @var{name} to be either a
5417 function symbol or an object symbol. There are five different syntaxes
5418 supported for the @var{type description} field, in order to provide
5419 compatibility with various other assemblers. The syntaxes supported are:
5422 .type <name>,#function
5423 .type <name>,#object
5425 .type <name>,@@function
5426 .type <name>,@@object
5428 .type <name>,%function
5429 .type <name>,%object
5431 .type <name>,"function"
5432 .type <name>,"object"
5434 .type <name> STT_FUNCTION
5435 .type <name> STT_OBJECT
5439 @section @code{.uleb128 @var{expressions}}
5441 @cindex @code{uleb128} directive
5442 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5443 compact, variable length representation of numbers used by the DWARF
5444 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5448 @section @code{.val @var{addr}}
5450 @cindex @code{val} directive
5451 @cindex COFF value attribute
5452 @cindex value attribute, COFF
5453 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5454 records the address @var{addr} as the value attribute of a symbol table
5458 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5459 configured for @code{b.out}, it accepts this directive but ignores it.
5465 @section @code{.version "@var{string}"}
5467 @cindex @code{.version}
5468 This directive creates a @code{.note} section and places into it an ELF
5469 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5474 @section @code{.vtable_entry @var{table}, @var{offset}}
5476 @cindex @code{.vtable_entry}
5477 This directive finds or creates a symbol @code{table} and creates a
5478 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5481 @section @code{.vtable_inherit @var{child}, @var{parent}}
5483 @cindex @code{.vtable_inherit}
5484 This directive finds the symbol @code{child} and finds or creates the symbol
5485 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5486 parent whose addend is the value of the child symbol. As a special case the
5487 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5492 @section @code{.weak @var{names}}
5494 @cindex @code{.weak}
5495 This directive sets the weak attribute on the comma separated list of symbol
5496 @code{names}. If the symbols do not already exist, they will be created.
5500 @section @code{.word @var{expressions}}
5502 @cindex @code{word} directive
5503 This directive expects zero or more @var{expressions}, of any section,
5504 separated by commas.
5507 For each expression, @command{@value{AS}} emits a 32-bit number.
5510 For each expression, @command{@value{AS}} emits a 16-bit number.
5515 The size of the number emitted, and its byte order,
5516 depend on what target computer the assembly is for.
5519 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5520 @c happen---32-bit addressability, period; no long/short jumps.
5521 @ifset DIFF-TBL-KLUGE
5522 @cindex difference tables altered
5523 @cindex altered difference tables
5525 @emph{Warning: Special Treatment to support Compilers}
5529 Machines with a 32-bit address space, but that do less than 32-bit
5530 addressing, require the following special treatment. If the machine of
5531 interest to you does 32-bit addressing (or doesn't require it;
5532 @pxref{Machine Dependencies}), you can ignore this issue.
5535 In order to assemble compiler output into something that works,
5536 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5537 Directives of the form @samp{.word sym1-sym2} are often emitted by
5538 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5539 directive of the form @samp{.word sym1-sym2}, and the difference between
5540 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5541 creates a @dfn{secondary jump table}, immediately before the next label.
5542 This secondary jump table is preceded by a short-jump to the
5543 first byte after the secondary table. This short-jump prevents the flow
5544 of control from accidentally falling into the new table. Inside the
5545 table is a long-jump to @code{sym2}. The original @samp{.word}
5546 contains @code{sym1} minus the address of the long-jump to
5549 If there were several occurrences of @samp{.word sym1-sym2} before the
5550 secondary jump table, all of them are adjusted. If there was a
5551 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5552 long-jump to @code{sym4} is included in the secondary jump table,
5553 and the @code{.word} directives are adjusted to contain @code{sym3}
5554 minus the address of the long-jump to @code{sym4}; and so on, for as many
5555 entries in the original jump table as necessary.
5558 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5559 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5560 assembly language programmers.
5563 @c end DIFF-TBL-KLUGE
5566 @section Deprecated Directives
5568 @cindex deprecated directives
5569 @cindex obsolescent directives
5570 One day these directives won't work.
5571 They are included for compatibility with older assemblers.
5578 @node Machine Dependencies
5579 @chapter Machine Dependent Features
5581 @cindex machine dependencies
5582 The machine instruction sets are (almost by definition) different on
5583 each machine where @command{@value{AS}} runs. Floating point representations
5584 vary as well, and @command{@value{AS}} often supports a few additional
5585 directives or command-line options for compatibility with other
5586 assemblers on a particular platform. Finally, some versions of
5587 @command{@value{AS}} support special pseudo-instructions for branch
5590 This chapter discusses most of these differences, though it does not
5591 include details on any machine's instruction set. For details on that
5592 subject, see the hardware manufacturer's manual.
5596 * AMD29K-Dependent:: AMD 29K Dependent Features
5599 * Alpha-Dependent:: Alpha Dependent Features
5602 * ARC-Dependent:: ARC Dependent Features
5605 * ARM-Dependent:: ARM Dependent Features
5608 * CRIS-Dependent:: CRIS Dependent Features
5611 * D10V-Dependent:: D10V Dependent Features
5614 * D30V-Dependent:: D30V Dependent Features
5617 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5620 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5623 * HPPA-Dependent:: HPPA Dependent Features
5626 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5629 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5632 * i860-Dependent:: Intel 80860 Dependent Features
5635 * i960-Dependent:: Intel 80960 Dependent Features
5638 * M32R-Dependent:: M32R Dependent Features
5641 * M68K-Dependent:: M680x0 Dependent Features
5644 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5647 * M88K-Dependent:: M880x0 Dependent Features
5650 * MIPS-Dependent:: MIPS Dependent Features
5653 * MMIX-Dependent:: MMIX Dependent Features
5656 * SH-Dependent:: Hitachi SH Dependent Features
5657 * SH64-Dependent:: Hitachi SH64 Dependent Features
5660 * PDP-11-Dependent:: PDP-11 Dependent Features
5663 * PJ-Dependent:: picoJava Dependent Features
5666 * PPC-Dependent:: PowerPC Dependent Features
5669 * Sparc-Dependent:: SPARC Dependent Features
5672 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5675 * V850-Dependent:: V850 Dependent Features
5678 * Z8000-Dependent:: Z8000 Dependent Features
5681 * Vax-Dependent:: VAX Dependent Features
5688 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5689 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5690 @c peculiarity: to preserve cross-references, there must be a node called
5691 @c "Machine Dependencies". Hence the conditional nodenames in each
5692 @c major node below. Node defaulting in makeinfo requires adjacency of
5693 @c node and sectioning commands; hence the repetition of @chapter BLAH
5694 @c in both conditional blocks.
5697 @include c-a29k.texi
5701 @include c-alpha.texi
5713 @include c-cris.texi
5718 @node Machine Dependencies
5719 @chapter Machine Dependent Features
5721 The machine instruction sets are different on each Hitachi chip family,
5722 and there are also some syntax differences among the families. This
5723 chapter describes the specific @command{@value{AS}} features for each
5727 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5728 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5729 * SH-Dependent:: Hitachi SH Dependent Features
5736 @include c-d10v.texi
5740 @include c-d30v.texi
5744 @include c-h8300.texi
5748 @include c-h8500.texi
5752 @include c-hppa.texi
5756 @include c-i370.texi
5760 @include c-i386.texi
5764 @include c-i860.texi
5768 @include c-i960.texi
5772 @include c-m32r.texi
5776 @include c-m68k.texi
5780 @include c-m68hc11.texi
5784 @include c-m88k.texi
5788 @include c-mips.texi
5792 @include c-mmix.texi
5796 @include c-ns32k.texi
5800 @include c-pdp11.texi
5813 @include c-sh64.texi
5817 @include c-sparc.texi
5821 @include c-tic54x.texi
5833 @include c-v850.texi
5837 @c reverse effect of @down at top of generic Machine-Dep chapter
5841 @node Reporting Bugs
5842 @chapter Reporting Bugs
5843 @cindex bugs in assembler
5844 @cindex reporting bugs in assembler
5846 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5848 Reporting a bug may help you by bringing a solution to your problem, or it may
5849 not. But in any case the principal function of a bug report is to help the
5850 entire community by making the next version of @command{@value{AS}} work better.
5851 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5853 In order for a bug report to serve its purpose, you must include the
5854 information that enables us to fix the bug.
5857 * Bug Criteria:: Have you found a bug?
5858 * Bug Reporting:: How to report bugs
5862 @section Have you found a bug?
5863 @cindex bug criteria
5865 If you are not sure whether you have found a bug, here are some guidelines:
5868 @cindex fatal signal
5869 @cindex assembler crash
5870 @cindex crash of assembler
5872 If the assembler gets a fatal signal, for any input whatever, that is a
5873 @command{@value{AS}} bug. Reliable assemblers never crash.
5875 @cindex error on valid input
5877 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5879 @cindex invalid input
5881 If @command{@value{AS}} does not produce an error message for invalid input, that
5882 is a bug. However, you should note that your idea of ``invalid input'' might
5883 be our idea of ``an extension'' or ``support for traditional practice''.
5886 If you are an experienced user of assemblers, your suggestions for improvement
5887 of @command{@value{AS}} are welcome in any case.
5891 @section How to report bugs
5893 @cindex assembler bugs, reporting
5895 A number of companies and individuals offer support for @sc{gnu} products. If
5896 you obtained @command{@value{AS}} from a support organization, we recommend you
5897 contact that organization first.
5899 You can find contact information for many support companies and
5900 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5903 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5904 to @samp{bug-binutils@@gnu.org}.
5906 The fundamental principle of reporting bugs usefully is this:
5907 @strong{report all the facts}. If you are not sure whether to state a
5908 fact or leave it out, state it!
5910 Often people omit facts because they think they know what causes the problem
5911 and assume that some details do not matter. Thus, you might assume that the
5912 name of a symbol you use in an example does not matter. Well, probably it does
5913 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5914 happens to fetch from the location where that name is stored in memory;
5915 perhaps, if the name were different, the contents of that location would fool
5916 the assembler into doing the right thing despite the bug. Play it safe and
5917 give a specific, complete example. That is the easiest thing for you to do,
5918 and the most helpful.
5920 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5921 it is new to us. Therefore, always write your bug reports on the assumption
5922 that the bug has not been reported previously.
5924 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5925 bell?'' Those bug reports are useless, and we urge everyone to
5926 @emph{refuse to respond to them} except to chide the sender to report
5929 To enable us to fix the bug, you should include all these things:
5933 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5934 it with the @samp{--version} argument.
5936 Without this, we will not know whether there is any point in looking for
5937 the bug in the current version of @command{@value{AS}}.
5940 Any patches you may have applied to the @command{@value{AS}} source.
5943 The type of machine you are using, and the operating system name and
5947 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5951 The command arguments you gave the assembler to assemble your example and
5952 observe the bug. To guarantee you will not omit something important, list them
5953 all. A copy of the Makefile (or the output from make) is sufficient.
5955 If we were to try to guess the arguments, we would probably guess wrong
5956 and then we might not encounter the bug.
5959 A complete input file that will reproduce the bug. If the bug is observed when
5960 the assembler is invoked via a compiler, send the assembler source, not the
5961 high level language source. Most compilers will produce the assembler source
5962 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5963 the options @samp{-v --save-temps}; this will save the assembler source in a
5964 file with an extension of @file{.s}, and also show you exactly how
5965 @command{@value{AS}} is being run.
5968 A description of what behavior you observe that you believe is
5969 incorrect. For example, ``It gets a fatal signal.''
5971 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5972 will certainly notice it. But if the bug is incorrect output, we might not
5973 notice unless it is glaringly wrong. You might as well not give us a chance to
5976 Even if the problem you experience is a fatal signal, you should still say so
5977 explicitly. Suppose something strange is going on, such as, your copy of
5978 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5979 library on your system. (This has happened!) Your copy might crash and ours
5980 would not. If you told us to expect a crash, then when ours fails to crash, we
5981 would know that the bug was not happening for us. If you had not told us to
5982 expect a crash, then we would not be able to draw any conclusion from our
5986 If you wish to suggest changes to the @command{@value{AS}} source, send us context
5987 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5988 option. Always send diffs from the old file to the new file. If you even
5989 discuss something in the @command{@value{AS}} source, refer to it by context, not
5992 The line numbers in our development sources will not match those in your
5993 sources. Your line numbers would convey no useful information to us.
5996 Here are some things that are not necessary:
6000 A description of the envelope of the bug.
6002 Often people who encounter a bug spend a lot of time investigating
6003 which changes to the input file will make the bug go away and which
6004 changes will not affect it.
6006 This is often time consuming and not very useful, because the way we
6007 will find the bug is by running a single example under the debugger
6008 with breakpoints, not by pure deduction from a series of examples.
6009 We recommend that you save your time for something else.
6011 Of course, if you can find a simpler example to report @emph{instead}
6012 of the original one, that is a convenience for us. Errors in the
6013 output will be easier to spot, running under the debugger will take
6014 less time, and so on.
6016 However, simplification is not vital; if you do not want to do this,
6017 report the bug anyway and send us the entire test case you used.
6020 A patch for the bug.
6022 A patch for the bug does help us if it is a good one. But do not omit
6023 the necessary information, such as the test case, on the assumption that
6024 a patch is all we need. We might see problems with your patch and decide
6025 to fix the problem another way, or we might not understand it at all.
6027 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6028 construct an example that will make the program follow a certain path through
6029 the code. If you do not send us the example, we will not be able to construct
6030 one, so we will not be able to verify that the bug is fixed.
6032 And if we cannot understand what bug you are trying to fix, or why your
6033 patch should be an improvement, we will not install it. A test case will
6034 help us to understand.
6037 A guess about what the bug is or what it depends on.
6039 Such guesses are usually wrong. Even we cannot guess right about such
6040 things without first using the debugger to find the facts.
6043 @node Acknowledgements
6044 @chapter Acknowledgements
6046 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6047 it is not meant as a slight. We just don't know about it. Send mail to the
6048 maintainer, and we'll correct the situation. Currently
6050 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6052 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6055 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6056 information and the 68k series machines, most of the preprocessing pass, and
6057 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6059 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6060 many bug fixes, including merging support for several processors, breaking GAS
6061 up to handle multiple object file format back ends (including heavy rewrite,
6062 testing, an integration of the coff and b.out back ends), adding configuration
6063 including heavy testing and verification of cross assemblers and file splits
6064 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6065 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6066 port (including considerable amounts of reverse engineering), a SPARC opcode
6067 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6068 assertions and made them work, much other reorganization, cleanup, and lint.
6070 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6071 in format-specific I/O modules.
6073 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6074 has done much work with it since.
6076 The Intel 80386 machine description was written by Eliot Dresselhaus.
6078 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6080 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6081 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6083 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6084 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6085 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6086 support a.out format.
6088 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6089 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6090 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6091 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6094 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6095 simplified the configuration of which versions accept which directives. He
6096 updated the 68k machine description so that Motorola's opcodes always produced
6097 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6098 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6099 cross-compilation support, and one bug in relaxation that took a week and
6100 required the proverbial one-bit fix.
6102 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6103 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6104 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6105 PowerPC assembler, and made a few other minor patches.
6107 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6109 Hewlett-Packard contributed support for the HP9000/300.
6111 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6112 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6113 formats). This work was supported by both the Center for Software Science at
6114 the University of Utah and Cygnus Support.
6116 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6117 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6118 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6119 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6120 and some initial 64-bit support).
6122 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6124 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6125 support for openVMS/Alpha.
6127 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6130 Several engineers at Cygnus Support have also provided many small bug fixes and
6131 configuration enhancements.
6133 Many others have contributed large or small bugfixes and enhancements. If
6134 you have contributed significant work and are not mentioned on this list, and
6135 want to be, let us know. Some of the history has been lost; we are not
6136 intentionally leaving anyone out.
6138 @node GNU Free Documentation License
6139 @chapter GNU Free Documentation License
6141 GNU Free Documentation License
6143 Version 1.1, March 2000
6145 Copyright (C) 2000 Free Software Foundation, Inc.
6146 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6148 Everyone is permitted to copy and distribute verbatim copies
6149 of this license document, but changing it is not allowed.
6154 The purpose of this License is to make a manual, textbook, or other
6155 written document "free" in the sense of freedom: to assure everyone
6156 the effective freedom to copy and redistribute it, with or without
6157 modifying it, either commercially or noncommercially. Secondarily,
6158 this License preserves for the author and publisher a way to get
6159 credit for their work, while not being considered responsible for
6160 modifications made by others.
6162 This License is a kind of "copyleft", which means that derivative
6163 works of the document must themselves be free in the same sense. It
6164 complements the GNU General Public License, which is a copyleft
6165 license designed for free software.
6167 We have designed this License in order to use it for manuals for free
6168 software, because free software needs free documentation: a free
6169 program should come with manuals providing the same freedoms that the
6170 software does. But this License is not limited to software manuals;
6171 it can be used for any textual work, regardless of subject matter or
6172 whether it is published as a printed book. We recommend this License
6173 principally for works whose purpose is instruction or reference.
6176 1. APPLICABILITY AND DEFINITIONS
6178 This License applies to any manual or other work that contains a
6179 notice placed by the copyright holder saying it can be distributed
6180 under the terms of this License. The "Document", below, refers to any
6181 such manual or work. Any member of the public is a licensee, and is
6184 A "Modified Version" of the Document means any work containing the
6185 Document or a portion of it, either copied verbatim, or with
6186 modifications and/or translated into another language.
6188 A "Secondary Section" is a named appendix or a front-matter section of
6189 the Document that deals exclusively with the relationship of the
6190 publishers or authors of the Document to the Document's overall subject
6191 (or to related matters) and contains nothing that could fall directly
6192 within that overall subject. (For example, if the Document is in part a
6193 textbook of mathematics, a Secondary Section may not explain any
6194 mathematics.) The relationship could be a matter of historical
6195 connection with the subject or with related matters, or of legal,
6196 commercial, philosophical, ethical or political position regarding
6199 The "Invariant Sections" are certain Secondary Sections whose titles
6200 are designated, as being those of Invariant Sections, in the notice
6201 that says that the Document is released under this License.
6203 The "Cover Texts" are certain short passages of text that are listed,
6204 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6205 the Document is released under this License.
6207 A "Transparent" copy of the Document means a machine-readable copy,
6208 represented in a format whose specification is available to the
6209 general public, whose contents can be viewed and edited directly and
6210 straightforwardly with generic text editors or (for images composed of
6211 pixels) generic paint programs or (for drawings) some widely available
6212 drawing editor, and that is suitable for input to text formatters or
6213 for automatic translation to a variety of formats suitable for input
6214 to text formatters. A copy made in an otherwise Transparent file
6215 format whose markup has been designed to thwart or discourage
6216 subsequent modification by readers is not Transparent. A copy that is
6217 not "Transparent" is called "Opaque".
6219 Examples of suitable formats for Transparent copies include plain
6220 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6221 or XML using a publicly available DTD, and standard-conforming simple
6222 HTML designed for human modification. Opaque formats include
6223 PostScript, PDF, proprietary formats that can be read and edited only
6224 by proprietary word processors, SGML or XML for which the DTD and/or
6225 processing tools are not generally available, and the
6226 machine-generated HTML produced by some word processors for output
6229 The "Title Page" means, for a printed book, the title page itself,
6230 plus such following pages as are needed to hold, legibly, the material
6231 this License requires to appear in the title page. For works in
6232 formats which do not have any title page as such, "Title Page" means
6233 the text near the most prominent appearance of the work's title,
6234 preceding the beginning of the body of the text.
6239 You may copy and distribute the Document in any medium, either
6240 commercially or noncommercially, provided that this License, the
6241 copyright notices, and the license notice saying this License applies
6242 to the Document are reproduced in all copies, and that you add no other
6243 conditions whatsoever to those of this License. You may not use
6244 technical measures to obstruct or control the reading or further
6245 copying of the copies you make or distribute. However, you may accept
6246 compensation in exchange for copies. If you distribute a large enough
6247 number of copies you must also follow the conditions in section 3.
6249 You may also lend copies, under the same conditions stated above, and
6250 you may publicly display copies.
6253 3. COPYING IN QUANTITY
6255 If you publish printed copies of the Document numbering more than 100,
6256 and the Document's license notice requires Cover Texts, you must enclose
6257 the copies in covers that carry, clearly and legibly, all these Cover
6258 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6259 the back cover. Both covers must also clearly and legibly identify
6260 you as the publisher of these copies. The front cover must present
6261 the full title with all words of the title equally prominent and
6262 visible. You may add other material on the covers in addition.
6263 Copying with changes limited to the covers, as long as they preserve
6264 the title of the Document and satisfy these conditions, can be treated
6265 as verbatim copying in other respects.
6267 If the required texts for either cover are too voluminous to fit
6268 legibly, you should put the first ones listed (as many as fit
6269 reasonably) on the actual cover, and continue the rest onto adjacent
6272 If you publish or distribute Opaque copies of the Document numbering
6273 more than 100, you must either include a machine-readable Transparent
6274 copy along with each Opaque copy, or state in or with each Opaque copy
6275 a publicly-accessible computer-network location containing a complete
6276 Transparent copy of the Document, free of added material, which the
6277 general network-using public has access to download anonymously at no
6278 charge using public-standard network protocols. If you use the latter
6279 option, you must take reasonably prudent steps, when you begin
6280 distribution of Opaque copies in quantity, to ensure that this
6281 Transparent copy will remain thus accessible at the stated location
6282 until at least one year after the last time you distribute an Opaque
6283 copy (directly or through your agents or retailers) of that edition to
6286 It is requested, but not required, that you contact the authors of the
6287 Document well before redistributing any large number of copies, to give
6288 them a chance to provide you with an updated version of the Document.
6293 You may copy and distribute a Modified Version of the Document under
6294 the conditions of sections 2 and 3 above, provided that you release
6295 the Modified Version under precisely this License, with the Modified
6296 Version filling the role of the Document, thus licensing distribution
6297 and modification of the Modified Version to whoever possesses a copy
6298 of it. In addition, you must do these things in the Modified Version:
6300 A. Use in the Title Page (and on the covers, if any) a title distinct
6301 from that of the Document, and from those of previous versions
6302 (which should, if there were any, be listed in the History section
6303 of the Document). You may use the same title as a previous version
6304 if the original publisher of that version gives permission.
6305 B. List on the Title Page, as authors, one or more persons or entities
6306 responsible for authorship of the modifications in the Modified
6307 Version, together with at least five of the principal authors of the
6308 Document (all of its principal authors, if it has less than five).
6309 C. State on the Title page the name of the publisher of the
6310 Modified Version, as the publisher.
6311 D. Preserve all the copyright notices of the Document.
6312 E. Add an appropriate copyright notice for your modifications
6313 adjacent to the other copyright notices.
6314 F. Include, immediately after the copyright notices, a license notice
6315 giving the public permission to use the Modified Version under the
6316 terms of this License, in the form shown in the Addendum below.
6317 G. Preserve in that license notice the full lists of Invariant Sections
6318 and required Cover Texts given in the Document's license notice.
6319 H. Include an unaltered copy of this License.
6320 I. Preserve the section entitled "History", and its title, and add to
6321 it an item stating at least the title, year, new authors, and
6322 publisher of the Modified Version as given on the Title Page. If
6323 there is no section entitled "History" in the Document, create one
6324 stating the title, year, authors, and publisher of the Document as
6325 given on its Title Page, then add an item describing the Modified
6326 Version as stated in the previous sentence.
6327 J. Preserve the network location, if any, given in the Document for
6328 public access to a Transparent copy of the Document, and likewise
6329 the network locations given in the Document for previous versions
6330 it was based on. These may be placed in the "History" section.
6331 You may omit a network location for a work that was published at
6332 least four years before the Document itself, or if the original
6333 publisher of the version it refers to gives permission.
6334 K. In any section entitled "Acknowledgements" or "Dedications",
6335 preserve the section's title, and preserve in the section all the
6336 substance and tone of each of the contributor acknowledgements
6337 and/or dedications given therein.
6338 L. Preserve all the Invariant Sections of the Document,
6339 unaltered in their text and in their titles. Section numbers
6340 or the equivalent are not considered part of the section titles.
6341 M. Delete any section entitled "Endorsements". Such a section
6342 may not be included in the Modified Version.
6343 N. Do not retitle any existing section as "Endorsements"
6344 or to conflict in title with any Invariant Section.
6346 If the Modified Version includes new front-matter sections or
6347 appendices that qualify as Secondary Sections and contain no material
6348 copied from the Document, you may at your option designate some or all
6349 of these sections as invariant. To do this, add their titles to the
6350 list of Invariant Sections in the Modified Version's license notice.
6351 These titles must be distinct from any other section titles.
6353 You may add a section entitled "Endorsements", provided it contains
6354 nothing but endorsements of your Modified Version by various
6355 parties--for example, statements of peer review or that the text has
6356 been approved by an organization as the authoritative definition of a
6359 You may add a passage of up to five words as a Front-Cover Text, and a
6360 passage of up to 25 words as a Back-Cover Text, to the end of the list
6361 of Cover Texts in the Modified Version. Only one passage of
6362 Front-Cover Text and one of Back-Cover Text may be added by (or
6363 through arrangements made by) any one entity. If the Document already
6364 includes a cover text for the same cover, previously added by you or
6365 by arrangement made by the same entity you are acting on behalf of,
6366 you may not add another; but you may replace the old one, on explicit
6367 permission from the previous publisher that added the old one.
6369 The author(s) and publisher(s) of the Document do not by this License
6370 give permission to use their names for publicity for or to assert or
6371 imply endorsement of any Modified Version.
6374 5. COMBINING DOCUMENTS
6376 You may combine the Document with other documents released under this
6377 License, under the terms defined in section 4 above for modified
6378 versions, provided that you include in the combination all of the
6379 Invariant Sections of all of the original documents, unmodified, and
6380 list them all as Invariant Sections of your combined work in its
6383 The combined work need only contain one copy of this License, and
6384 multiple identical Invariant Sections may be replaced with a single
6385 copy. If there are multiple Invariant Sections with the same name but
6386 different contents, make the title of each such section unique by
6387 adding at the end of it, in parentheses, the name of the original
6388 author or publisher of that section if known, or else a unique number.
6389 Make the same adjustment to the section titles in the list of
6390 Invariant Sections in the license notice of the combined work.
6392 In the combination, you must combine any sections entitled "History"
6393 in the various original documents, forming one section entitled
6394 "History"; likewise combine any sections entitled "Acknowledgements",
6395 and any sections entitled "Dedications". You must delete all sections
6396 entitled "Endorsements."
6399 6. COLLECTIONS OF DOCUMENTS
6401 You may make a collection consisting of the Document and other documents
6402 released under this License, and replace the individual copies of this
6403 License in the various documents with a single copy that is included in
6404 the collection, provided that you follow the rules of this License for
6405 verbatim copying of each of the documents in all other respects.
6407 You may extract a single document from such a collection, and distribute
6408 it individually under this License, provided you insert a copy of this
6409 License into the extracted document, and follow this License in all
6410 other respects regarding verbatim copying of that document.
6413 7. AGGREGATION WITH INDEPENDENT WORKS
6415 A compilation of the Document or its derivatives with other separate
6416 and independent documents or works, in or on a volume of a storage or
6417 distribution medium, does not as a whole count as a Modified Version
6418 of the Document, provided no compilation copyright is claimed for the
6419 compilation. Such a compilation is called an "aggregate", and this
6420 License does not apply to the other self-contained works thus compiled
6421 with the Document, on account of their being thus compiled, if they
6422 are not themselves derivative works of the Document.
6424 If the Cover Text requirement of section 3 is applicable to these
6425 copies of the Document, then if the Document is less than one quarter
6426 of the entire aggregate, the Document's Cover Texts may be placed on
6427 covers that surround only the Document within the aggregate.
6428 Otherwise they must appear on covers around the whole aggregate.
6433 Translation is considered a kind of modification, so you may
6434 distribute translations of the Document under the terms of section 4.
6435 Replacing Invariant Sections with translations requires special
6436 permission from their copyright holders, but you may include
6437 translations of some or all Invariant Sections in addition to the
6438 original versions of these Invariant Sections. You may include a
6439 translation of this License provided that you also include the
6440 original English version of this License. In case of a disagreement
6441 between the translation and the original English version of this
6442 License, the original English version will prevail.
6447 You may not copy, modify, sublicense, or distribute the Document except
6448 as expressly provided for under this License. Any other attempt to
6449 copy, modify, sublicense or distribute the Document is void, and will
6450 automatically terminate your rights under this License. However,
6451 parties who have received copies, or rights, from you under this
6452 License will not have their licenses terminated so long as such
6453 parties remain in full compliance.
6456 10. FUTURE REVISIONS OF THIS LICENSE
6458 The Free Software Foundation may publish new, revised versions
6459 of the GNU Free Documentation License from time to time. Such new
6460 versions will be similar in spirit to the present version, but may
6461 differ in detail to address new problems or concerns. See
6462 http://www.gnu.org/copyleft/.
6464 Each version of the License is given a distinguishing version number.
6465 If the Document specifies that a particular numbered version of this
6466 License "or any later version" applies to it, you have the option of
6467 following the terms and conditions either of that specified version or
6468 of any later version that has been published (not as a draft) by the
6469 Free Software Foundation. If the Document does not specify a version
6470 number of this License, you may choose any version ever published (not
6471 as a draft) by the Free Software Foundation.
6474 ADDENDUM: How to use this License for your documents
6476 To use this License in a document you have written, include a copy of
6477 the License in the document and put the following copyright and
6478 license notices just after the title page:
6481 Copyright (c) YEAR YOUR NAME.
6482 Permission is granted to copy, distribute and/or modify this document
6483 under the terms of the GNU Free Documentation License, Version 1.1
6484 or any later version published by the Free Software Foundation;
6485 with the Invariant Sections being LIST THEIR TITLES, with the
6486 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6487 A copy of the license is included in the section entitled "GNU
6488 Free Documentation License".
6491 If you have no Invariant Sections, write "with no Invariant Sections"
6492 instead of saying which ones are invariant. If you have no
6493 Front-Cover Texts, write "no Front-Cover Texts" instead of
6494 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6496 If your document contains nontrivial examples of program code, we
6497 recommend releasing these examples in parallel under your choice of
6498 free software license, such as the GNU General Public License,
6499 to permit their use in free software.
projects / external / binutils.git / blob