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.
121 * Gas: (as). The GNU assembler.
130 This file documents the GNU Assembler "@value{AS}".
132 @c man begin COPYRIGHT
133 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
135 Permission is granted to copy, distribute and/or modify this document
136 under the terms of the GNU Free Documentation License, Version 1.1
137 or any later version published by the Free Software Foundation;
138 with no Invariant Sections, with no Front-Cover Texts, and with no
139 Back-Cover Texts. A copy of the license is included in the
140 section entitled "GNU Free Documentation License".
145 Permission is granted to process this file through Tex and print the
146 results, provided the printed document carries copying permission
147 notice identical to this one except for the removal of this paragraph
148 (this paragraph not being relevant to the printed manual).
154 @title Using @value{AS}
155 @subtitle The @sc{gnu} Assembler
157 @subtitle for the @value{TARGET} family
160 @subtitle Version @value{VERSION}
163 The Free Software Foundation Inc. thanks The Nice Computer
164 Company of Australia for loaning Dean Elsner to write the
165 first (Vax) version of @command{as} for Project @sc{gnu}.
166 The proprietors, management and staff of TNCCA thank FSF for
167 distracting the boss while they got some work
170 @author Dean Elsner, Jay Fenlason & friends
174 \hfill {\it Using {\tt @value{AS}}}\par
175 \hfill Edited by Cygnus Support\par
177 %"boxit" macro for figures:
178 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
179 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
180 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
181 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
182 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
185 @vskip 0pt plus 1filll
186 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
188 Permission is granted to copy, distribute and/or modify this document
189 under the terms of the GNU Free Documentation License, Version 1.1
190 or any later version published by the Free Software Foundation;
191 with no Invariant Sections, with no Front-Cover Texts, and with no
192 Back-Cover Texts. A copy of the license is included in the
193 section entitled "GNU Free Documentation License".
199 @top Using @value{AS}
201 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
204 This version of the file describes @command{@value{AS}} configured to generate
205 code for @value{TARGET} architectures.
208 This document is distributed under the terms of the GNU Free
209 Documentation License. A copy of the license is included in the
210 section entitled "GNU Free Documentation License".
213 * Overview:: Overview
214 * Invoking:: Command-Line Options
216 * Sections:: Sections and Relocation
218 * Expressions:: Expressions
219 * Pseudo Ops:: Assembler Directives
220 * Machine Dependencies:: Machine Dependent Features
221 * Reporting Bugs:: Reporting Bugs
222 * Acknowledgements:: Who Did What
223 * GNU Free Documentation License:: GNU Free Documentation License
231 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
233 This version of the manual describes @command{@value{AS}} configured to generate
234 code for @value{TARGET} architectures.
238 @cindex invocation summary
239 @cindex option summary
240 @cindex summary of options
241 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
242 @pxref{Invoking,,Comand-Line Options}.
244 @c man title AS the portable GNU assembler.
248 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
252 @c We don't use deffn and friends for the following because they seem
253 @c to be limited to one line for the header.
255 @c man begin SYNOPSIS
256 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
257 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
258 [@b{-J}] [@b{-K}] [@b{-L}]
259 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
260 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
261 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
262 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
263 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
264 [@b{--}|@var{files} @dots{}]
266 @c Target dependent options are listed below. Keep the list sorted.
267 @c Add an empty line for separation.
269 @c am29k has no machine-dependent assembler options
273 @emph{Target Alpha options:}
275 [@b{-mdebug} | @b{-no-mdebug}]
276 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
277 [@b{-F}] [@b{-32addr}]
281 @emph{Target ARC options:}
287 @emph{Target ARM options:}
288 @c Don't document the deprecated options
289 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
290 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
291 [@b{-mfpu}=@var{floating-point-fromat}]
294 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
295 @b{-mapcs-reentrant}]
296 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
300 @emph{Target CRIS options:}
301 [@b{--underscore} | @b{--no-underscore}]
303 [@b{--emulation=criself} | @b{--emulation=crisaout}]
304 @c Deprecated -- deliberately not documented.
309 @emph{Target D10V options:}
314 @emph{Target D30V options:}
315 [@b{-O}|@b{-n}|@b{-N}]
318 @c Hitachi family chips have no machine-dependent assembler options
321 @c HPPA has no machine-dependent assembler options (yet).
325 @emph{Target i386 options:}
330 @emph{Target i960 options:}
331 @c see md_parse_option in tc-i960.c
332 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
334 [@b{-b}] [@b{-no-relax}]
338 @emph{Target M32R options:}
339 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
344 @emph{Target M680X0 options:}
345 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
349 @emph{Target M68HC11 options:}
350 [@b{-m68hc11}|@b{-m68hc12}]
351 [@b{--force-long-branchs}] [@b{--short-branchs}]
352 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
353 [@b{--print-opcodes}] [@b{--generate-example}]
357 @emph{Target MCORE options:}
358 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
359 [@b{-mcpu=[210|340]}]
363 @emph{Target MIPS options:}
364 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
365 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
366 [@b{-mips32}] [@b{-mips64}]
367 [@b{-m4650}] [@b{-no-m4650}]
368 [@b{--trap}] [@b{--break}] [@b{-n}]
369 [@b{--emulation}=@var{name} ]
373 @emph{Target MMIX options:}
374 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
375 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
376 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
377 [@b{--linker-allocated-gregs}]
381 @emph{Target PDP11 options:}
382 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
383 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
384 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
388 @emph{Target picoJava options:}
393 @emph{Target PowerPC options:}
394 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
395 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
396 @b{-mbooke32}|@b{-mbooke64}]
397 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
398 [@b{-mregnames}|@b{-mno-regnames}]
399 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
400 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
401 [@b{-msolaris}|@b{-mno-solaris}]
405 @emph{Target SPARC options:}
406 @c The order here is important. See c-sparc.texi.
407 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
408 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
409 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
414 @emph{Target TIC54X options:}
415 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
416 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
419 @c Z8000 has no machine-dependent assembler options
428 Turn on listings, in any of a variety of ways:
432 omit false conditionals
435 omit debugging directives
438 include high-level source
444 include macro expansions
447 omit forms processing
453 set the name of the listing file
456 You may combine these options; for example, use @samp{-aln} for assembly
457 listing without forms processing. The @samp{=file} option, if used, must be
458 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
461 Ignored. This option is accepted for script compatibility with calls to
464 @item --defsym @var{sym}=@var{value}
465 Define the symbol @var{sym} to be @var{value} before assembling the input file.
466 @var{value} must be an integer constant. As in C, a leading @samp{0x}
467 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
470 ``fast''---skip whitespace and comment preprocessing (assume source is
474 Generate stabs debugging information for each assembler line. This
475 may help debugging assembler code, if the debugger can handle it.
478 Generate DWARF2 debugging information for each assembler line. This
479 may help debugging assembler code, if the debugger can handle it. Note - this
480 option is only supported by some targets, not all of them.
483 Print a summary of the command line options and exit.
486 Print a summary of all target specific options and exit.
489 Add directory @var{dir} to the search list for @code{.include} directives.
492 Don't warn about signed overflow.
495 @ifclear DIFF-TBL-KLUGE
496 This option is accepted but has no effect on the @value{TARGET} family.
498 @ifset DIFF-TBL-KLUGE
499 Issue warnings when difference tables altered for long displacements.
504 Keep (in the symbol table) local symbols. On traditional a.out systems
505 these start with @samp{L}, but different systems have different local
508 @item --listing-lhs-width=@var{number}
509 Set the maximum width, in words, of the output data column for an assembler
510 listing to @var{number}.
512 @item --listing-lhs-width2=@var{number}
513 Set the maximum width, in words, of the output data column for continuation
514 lines in an assembler listing to @var{number}.
516 @item --listing-rhs-width=@var{number}
517 Set the maximum width of an input source line, as displayed in a listing, to
520 @item --listing-cont-lines=@var{number}
521 Set the maximum number of lines printed in a listing for a single line of input
524 @item -o @var{objfile}
525 Name the object-file output from @command{@value{AS}} @var{objfile}.
528 Fold the data section into the text section.
531 Print the maximum space (in bytes) and total time (in seconds) used by
534 @item --strip-local-absolute
535 Remove local absolute symbols from the outgoing symbol table.
539 Print the @command{as} version.
542 Print the @command{as} version and exit.
546 Suppress warning messages.
548 @item --fatal-warnings
549 Treat warnings as errors.
552 Don't suppress warning messages or treat them as errors.
561 Generate an object file even after errors.
563 @item -- | @var{files} @dots{}
564 Standard input, or source files to assemble.
569 The following options are available when @value{AS} is configured for
574 This option selects the core processor variant.
576 Select either big-endian (-EB) or little-endian (-EL) output.
581 The following options are available when @value{AS} is configured for the ARM
585 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
586 Specify which ARM processor variant is the target.
587 @item -march=@var{architecture}[+@var{extension}@dots{}]
588 Specify which ARM architecture variant is used by the target.
589 @item -mfpu=@var{floating-point-format}
590 Select which Floating Point architecture is the target.
592 Enable Thumb only instruction decoding.
593 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
594 Select which procedure calling convention is in use.
596 Select either big-endian (-EB) or little-endian (-EL) output.
597 @item -mthumb-interwork
598 Specify that the code has been generated with interworking between Thumb and
601 Specify that PIC code has been generated.
606 See the info pages for documentation of the CRIS-specific options.
610 The following options are available when @value{AS} is configured for
613 @cindex D10V optimization
614 @cindex optimization, D10V
616 Optimize output by parallelizing instructions.
621 The following options are available when @value{AS} is configured for a D30V
624 @cindex D30V optimization
625 @cindex optimization, D30V
627 Optimize output by parallelizing instructions.
631 Warn when nops are generated.
633 @cindex D30V nops after 32-bit multiply
635 Warn when a nop after a 32-bit multiply instruction is generated.
640 The following options are available when @value{AS} is configured for the
641 Intel 80960 processor.
644 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
645 Specify which variant of the 960 architecture is the target.
648 Add code to collect statistics about branches taken.
651 Do not alter compare-and-branch instructions for long displacements;
658 The following options are available when @value{AS} is configured for the
659 Mitsubishi M32R series.
664 Specify which processor in the M32R family is the target. The default
665 is normally the M32R, but this option changes it to the M32RX.
667 @item --warn-explicit-parallel-conflicts or --Wp
668 Produce warning messages when questionable parallel constructs are
671 @item --no-warn-explicit-parallel-conflicts or --Wnp
672 Do not produce warning messages when questionable parallel constructs are
679 The following options are available when @value{AS} is configured for the
680 Motorola 68000 series.
685 Shorten references to undefined symbols, to one word instead of two.
687 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
688 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
689 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
690 Specify what processor in the 68000 family is the target. The default
691 is normally the 68020, but this can be changed at configuration time.
693 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
694 The target machine does (or does not) have a floating-point coprocessor.
695 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
696 the basic 68000 is not compatible with the 68881, a combination of the
697 two can be specified, since it's possible to do emulation of the
698 coprocessor instructions with the main processor.
700 @item -m68851 | -mno-68851
701 The target machine does (or does not) have a memory-management
702 unit coprocessor. The default is to assume an MMU for 68020 and up.
709 For details about the PDP-11 machine dependent features options,
710 see @ref{PDP-11-Options}.
713 @item -mpic | -mno-pic
714 Generate position-independent (or position-dependent) code. The
715 default is @option{-mpic}.
718 @itemx -mall-extensions
719 Enable all instruction set extensions. This is the default.
721 @item -mno-extensions
722 Disable all instruction set extensions.
724 @item -m@var{extension} | -mno-@var{extension}
725 Enable (or disable) a particular instruction set extension.
728 Enable the instruction set extensions supported by a particular CPU, and
729 disable all other extensions.
731 @item -m@var{machine}
732 Enable the instruction set extensions supported by a particular machine
733 model, and disable all other extensions.
739 The following options are available when @value{AS} is configured for
740 a picoJava processor.
744 @cindex PJ endianness
745 @cindex endianness, PJ
746 @cindex big endian output, PJ
748 Generate ``big endian'' format output.
750 @cindex little endian output, PJ
752 Generate ``little endian'' format output.
758 The following options are available when @value{AS} is configured for the
759 Motorola 68HC11 or 68HC12 series.
763 @item -m68hc11 | -m68hc12
764 Specify what processor is the target. The default is
765 defined by the configuration option when building the assembler.
767 @item --force-long-branchs
768 Relative branches are turned into absolute ones. This concerns
769 conditional branches, unconditional branches and branches to a
772 @item -S | --short-branchs
773 Do not turn relative branchs into absolute ones
774 when the offset is out of range.
776 @item --strict-direct-mode
777 Do not turn the direct addressing mode into extended addressing mode
778 when the instruction does not support direct addressing mode.
780 @item --print-insn-syntax
781 Print the syntax of instruction in case of error.
783 @item --print-opcodes
784 print the list of instructions with syntax and then exit.
786 @item --generate-example
787 print an example of instruction for each possible instruction and then exit.
788 This option is only useful for testing @command{@value{AS}}.
794 The following options are available when @command{@value{AS}} is configured
795 for the SPARC architecture:
798 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
799 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
800 Explicitly select a variant of the SPARC architecture.
802 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
803 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
805 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
806 UltraSPARC extensions.
808 @item -xarch=v8plus | -xarch=v8plusa
809 For compatibility with the Solaris v9 assembler. These options are
810 equivalent to -Av8plus and -Av8plusa, respectively.
813 Warn when the assembler switches to another architecture.
818 The following options are available when @value{AS} is configured for the 'c54x
823 Enable extended addressing mode. All addresses and relocations will assume
824 extended addressing (usually 23 bits).
825 @item -mcpu=@var{CPU_VERSION}
826 Sets the CPU version being compiled for.
827 @item -merrors-to-file @var{FILENAME}
828 Redirect error output to a file, for broken systems which don't support such
829 behaviour in the shell.
834 The following options are available when @value{AS} is configured for
839 This option sets the largest size of an object that can be referenced
840 implicitly with the @code{gp} register. It is only accepted for targets that
841 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
843 @cindex MIPS endianness
844 @cindex endianness, MIPS
845 @cindex big endian output, MIPS
847 Generate ``big endian'' format output.
849 @cindex little endian output, MIPS
851 Generate ``little endian'' format output.
860 Generate code for a particular MIPS Instruction Set Architecture level.
861 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
862 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
864 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
865 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
866 processors, respectively.
870 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
871 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
872 instructions around accesses to the @samp{HI} and @samp{LO} registers.
873 @samp{-no-m4650} turns off this option.
875 @item -mcpu=@var{CPU}
876 Generate code for a particular MIPS cpu. It is exactly equivalent to
877 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
881 @item --emulation=@var{name}
882 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
883 for some other target, in all respects, including output format (choosing
884 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
885 debugging information or store symbol table information, and default
886 endianness. The available configuration names are: @samp{mipsecoff},
887 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
888 @samp{mipsbelf}. The first two do not alter the default endianness from that
889 of the primary target for which the assembler was configured; the others change
890 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
891 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
892 selection in any case.
894 This option is currently supported only when the primary target
895 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
896 Furthermore, the primary target or others specified with
897 @samp{--enable-targets=@dots{}} at configuration time must include support for
898 the other format, if both are to be available. For example, the Irix 5
899 configuration includes support for both.
901 Eventually, this option will support more configurations, with more
902 fine-grained control over the assembler's behavior, and will be supported for
906 @command{@value{AS}} ignores this option. It is accepted for compatibility with
914 Control how to deal with multiplication overflow and division by zero.
915 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
916 (and only work for Instruction Set Architecture level 2 and higher);
917 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
921 When this option is used, @command{@value{AS}} will issue a warning every
922 time it generates a nop instruction from a macro.
927 The following options are available when @value{AS} is configured for
933 Enable or disable the JSRI to BSR transformation. By default this is enabled.
934 The command line option @samp{-nojsri2bsr} can be used to disable it.
938 Enable or disable the silicon filter behaviour. By default this is disabled.
939 The default can be overridden by the @samp{-sifilter} command line option.
942 Alter jump instructions for long displacements.
944 @item -mcpu=[210|340]
945 Select the cpu type on the target hardware. This controls which instructions
949 Assemble for a big endian target.
952 Assemble for a little endian target.
958 See the info pages for documentation of the MMIX-specific options.
964 * Manual:: Structure of this Manual
965 * GNU Assembler:: The GNU Assembler
966 * Object Formats:: Object File Formats
967 * Command Line:: Command Line
968 * Input Files:: Input Files
969 * Object:: Output (Object) File
970 * Errors:: Error and Warning Messages
974 @section Structure of this Manual
976 @cindex manual, structure and purpose
977 This manual is intended to describe what you need to know to use
978 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
979 notation for symbols, constants, and expressions; the directives that
980 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
983 We also cover special features in the @value{TARGET}
984 configuration of @command{@value{AS}}, including assembler directives.
987 This manual also describes some of the machine-dependent features of
988 various flavors of the assembler.
991 @cindex machine instructions (not covered)
992 On the other hand, this manual is @emph{not} intended as an introduction
993 to programming in assembly language---let alone programming in general!
994 In a similar vein, we make no attempt to introduce the machine
995 architecture; we do @emph{not} describe the instruction set, standard
996 mnemonics, registers or addressing modes that are standard to a
997 particular architecture.
999 You may want to consult the manufacturer's
1000 machine architecture manual for this information.
1004 For information on the H8/300 machine instruction set, see @cite{H8/300
1005 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1006 see @cite{H8/300H Series Programming Manual} (Hitachi).
1009 For information on the H8/500 machine instruction set, see @cite{H8/500
1010 Series Programming Manual} (Hitachi M21T001).
1013 For information on the Hitachi SH machine instruction set, see
1014 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1017 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1021 @c I think this is premature---doc@cygnus.com, 17jan1991
1023 Throughout this manual, we assume that you are running @dfn{GNU},
1024 the portable operating system from the @dfn{Free Software
1025 Foundation, Inc.}. This restricts our attention to certain kinds of
1026 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1027 once this assumption is granted examples and definitions need less
1030 @command{@value{AS}} is part of a team of programs that turn a high-level
1031 human-readable series of instructions into a low-level
1032 computer-readable series of instructions. Different versions of
1033 @command{@value{AS}} are used for different kinds of computer.
1036 @c There used to be a section "Terminology" here, which defined
1037 @c "contents", "byte", "word", and "long". Defining "word" to any
1038 @c particular size is confusing when the .word directive may generate 16
1039 @c bits on one machine and 32 bits on another; in general, for the user
1040 @c version of this manual, none of these terms seem essential to define.
1041 @c They were used very little even in the former draft of the manual;
1042 @c this draft makes an effort to avoid them (except in names of
1046 @section The GNU Assembler
1048 @c man begin DESCRIPTION
1050 @sc{gnu} @command{as} is really a family of assemblers.
1052 This manual describes @command{@value{AS}}, a member of that family which is
1053 configured for the @value{TARGET} architectures.
1055 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1056 should find a fairly similar environment when you use it on another
1057 architecture. Each version has much in common with the others,
1058 including object file formats, most assembler directives (often called
1059 @dfn{pseudo-ops}) and assembler syntax.@refill
1061 @cindex purpose of @sc{gnu} assembler
1062 @command{@value{AS}} is primarily intended to assemble the output of the
1063 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1064 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1065 assemble correctly everything that other assemblers for the same
1066 machine would assemble.
1068 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1071 @c This remark should appear in generic version of manual; assumption
1072 @c here is that generic version sets M680x0.
1073 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1074 assembler for the same architecture; for example, we know of several
1075 incompatible versions of 680x0 assembly language syntax.
1080 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1081 program in one pass of the source file. This has a subtle impact on the
1082 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1084 @node Object Formats
1085 @section Object File Formats
1087 @cindex object file format
1088 The @sc{gnu} assembler can be configured to produce several alternative
1089 object file formats. For the most part, this does not affect how you
1090 write assembly language programs; but directives for debugging symbols
1091 are typically different in different file formats. @xref{Symbol
1092 Attributes,,Symbol Attributes}.
1095 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1096 @value{OBJ-NAME} format object files.
1098 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1100 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1101 @code{a.out} or COFF format object files.
1104 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1105 @code{b.out} or COFF format object files.
1108 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1109 SOM or ELF format object files.
1114 @section Command Line
1116 @cindex command line conventions
1118 After the program name @command{@value{AS}}, the command line may contain
1119 options and file names. Options may appear in any order, and may be
1120 before, after, or between file names. The order of file names is
1123 @cindex standard input, as input file
1125 @file{--} (two hyphens) by itself names the standard input file
1126 explicitly, as one of the files for @command{@value{AS}} to assemble.
1128 @cindex options, command line
1129 Except for @samp{--} any command line argument that begins with a
1130 hyphen (@samp{-}) is an option. Each option changes the behavior of
1131 @command{@value{AS}}. No option changes the way another option works. An
1132 option is a @samp{-} followed by one or more letters; the case of
1133 the letter is important. All options are optional.
1135 Some options expect exactly one file name to follow them. The file
1136 name may either immediately follow the option's letter (compatible
1137 with older assemblers) or it may be the next command argument (@sc{gnu}
1138 standard). These two command lines are equivalent:
1141 @value{AS} -o my-object-file.o mumble.s
1142 @value{AS} -omy-object-file.o mumble.s
1146 @section Input Files
1149 @cindex source program
1150 @cindex files, input
1151 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1152 describe the program input to one run of @command{@value{AS}}. The program may
1153 be in one or more files; how the source is partitioned into files
1154 doesn't change the meaning of the source.
1156 @c I added "con" prefix to "catenation" just to prove I can overcome my
1157 @c APL training... doc@cygnus.com
1158 The source program is a concatenation of the text in all the files, in the
1161 @c man begin DESCRIPTION
1162 Each time you run @command{@value{AS}} it assembles exactly one source
1163 program. The source program is made up of one or more files.
1164 (The standard input is also a file.)
1166 You give @command{@value{AS}} a command line that has zero or more input file
1167 names. The input files are read (from left file name to right). A
1168 command line argument (in any position) that has no special meaning
1169 is taken to be an input file name.
1171 If you give @command{@value{AS}} no file names it attempts to read one input file
1172 from the @command{@value{AS}} standard input, which is normally your terminal. You
1173 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1176 Use @samp{--} if you need to explicitly name the standard input file
1177 in your command line.
1179 If the source is empty, @command{@value{AS}} produces a small, empty object
1184 @subheading Filenames and Line-numbers
1186 @cindex input file linenumbers
1187 @cindex line numbers, in input files
1188 There are two ways of locating a line in the input file (or files) and
1189 either may be used in reporting error messages. One way refers to a line
1190 number in a physical file; the other refers to a line number in a
1191 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1193 @dfn{Physical files} are those files named in the command line given
1194 to @command{@value{AS}}.
1196 @dfn{Logical files} are simply names declared explicitly by assembler
1197 directives; they bear no relation to physical files. Logical file names help
1198 error messages reflect the original source file, when @command{@value{AS}} source
1199 is itself synthesized from other files. @command{@value{AS}} understands the
1200 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1201 @ref{File,,@code{.file}}.
1204 @section Output (Object) File
1210 Every time you run @command{@value{AS}} it produces an output file, which is
1211 your assembly language program translated into numbers. This file
1212 is the object file. Its default name is
1220 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1222 You can give it another name by using the @option{-o} option. Conventionally,
1223 object file names end with @file{.o}. The default name is used for historical
1224 reasons: older assemblers were capable of assembling self-contained programs
1225 directly into a runnable program. (For some formats, this isn't currently
1226 possible, but it can be done for the @code{a.out} format.)
1230 The object file is meant for input to the linker @code{@value{LD}}. It contains
1231 assembled program code, information to help @code{@value{LD}} integrate
1232 the assembled program into a runnable file, and (optionally) symbolic
1233 information for the debugger.
1235 @c link above to some info file(s) like the description of a.out.
1236 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1239 @section Error and Warning Messages
1241 @c man begin DESCRIPTION
1243 @cindex error messages
1244 @cindex warning messages
1245 @cindex messages from assembler
1246 @command{@value{AS}} may write warnings and error messages to the standard error
1247 file (usually your terminal). This should not happen when a compiler
1248 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1249 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1250 grave problem that stops the assembly.
1254 @cindex format of warning messages
1255 Warning messages have the format
1258 file_name:@b{NNN}:Warning Message Text
1262 @cindex line numbers, in warnings/errors
1263 (where @b{NNN} is a line number). If a logical file name has been given
1264 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1265 the current input file is used. If a logical line number was given
1267 (@pxref{Line,,@code{.line}})
1271 (@pxref{Line,,@code{.line}})
1274 (@pxref{Ln,,@code{.ln}})
1277 then it is used to calculate the number printed,
1278 otherwise the actual line in the current source file is printed. The
1279 message text is intended to be self explanatory (in the grand Unix
1282 @cindex format of error messages
1283 Error messages have the format
1285 file_name:@b{NNN}:FATAL:Error Message Text
1287 The file name and line number are derived as for warning
1288 messages. The actual message text may be rather less explanatory
1289 because many of them aren't supposed to happen.
1292 @chapter Command-Line Options
1294 @cindex options, all versions of assembler
1295 This chapter describes command-line options available in @emph{all}
1296 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1298 to the @value{TARGET}.
1301 to particular machine architectures.
1304 @c man begin DESCRIPTION
1306 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1307 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1308 The assembler arguments must be separated from each other (and the @samp{-Wa})
1309 by commas. For example:
1312 gcc -c -g -O -Wa,-alh,-L file.c
1316 This passes two options to the assembler: @samp{-alh} (emit a listing to
1317 standard output with with high-level and assembly source) and @samp{-L} (retain
1318 local symbols in the symbol table).
1320 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1321 command-line options are automatically passed to the assembler by the compiler.
1322 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1323 precisely what options it passes to each compilation pass, including the
1329 * a:: -a[cdhlns] enable listings
1330 * D:: -D for compatibility
1331 * f:: -f to work faster
1332 * I:: -I for .include search path
1333 @ifclear DIFF-TBL-KLUGE
1334 * K:: -K for compatibility
1336 @ifset DIFF-TBL-KLUGE
1337 * K:: -K for difference tables
1340 * L:: -L to retain local labels
1341 * listing:: --listing-XXX to configure listing output
1342 * M:: -M or --mri to assemble in MRI compatibility mode
1343 * MD:: --MD for dependency tracking
1344 * o:: -o to name the object file
1345 * R:: -R to join data and text sections
1346 * statistics:: --statistics to see statistics about assembly
1347 * traditional-format:: --traditional-format for compatible output
1348 * v:: -v to announce version
1349 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1350 * Z:: -Z to make object file even after errors
1354 @section Enable Listings: @option{-a[cdhlns]}
1363 @cindex listings, enabling
1364 @cindex assembly listings, enabling
1366 These options enable listing output from the assembler. By itself,
1367 @samp{-a} requests high-level, assembly, and symbols listing.
1368 You can use other letters to select specific options for the list:
1369 @samp{-ah} requests a high-level language listing,
1370 @samp{-al} requests an output-program assembly listing, and
1371 @samp{-as} requests a symbol table listing.
1372 High-level listings require that a compiler debugging option like
1373 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1376 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1377 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1378 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1379 omitted from the listing.
1381 Use the @samp{-ad} option to omit debugging directives from the
1384 Once you have specified one of these options, you can further control
1385 listing output and its appearance using the directives @code{.list},
1386 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1388 The @samp{-an} option turns off all forms processing.
1389 If you do not request listing output with one of the @samp{-a} options, the
1390 listing-control directives have no effect.
1392 The letters after @samp{-a} may be combined into one option,
1393 @emph{e.g.}, @samp{-aln}.
1395 Note if the assembler source is coming from the standard input (eg because it
1396 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1397 is being used) then the listing will not contain any comments or preprocessor
1398 directives. This is because the listing code buffers input source lines from
1399 stdin only after they have been preprocessed by the assembler. This reduces
1400 memory usage and makes the code more efficient.
1403 @section @option{-D}
1406 This option has no effect whatsoever, but it is accepted to make it more
1407 likely that scripts written for other assemblers also work with
1408 @command{@value{AS}}.
1411 @section Work Faster: @option{-f}
1414 @cindex trusted compiler
1415 @cindex faster processing (@option{-f})
1416 @samp{-f} should only be used when assembling programs written by a
1417 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1418 and comment preprocessing on
1419 the input file(s) before assembling them. @xref{Preprocessing,
1423 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1424 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1429 @section @code{.include} search path: @option{-I} @var{path}
1431 @kindex -I @var{path}
1432 @cindex paths for @code{.include}
1433 @cindex search path for @code{.include}
1434 @cindex @code{include} directive search path
1435 Use this option to add a @var{path} to the list of directories
1436 @command{@value{AS}} searches for files specified in @code{.include}
1437 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1438 many times as necessary to include a variety of paths. The current
1439 working directory is always searched first; after that, @command{@value{AS}}
1440 searches any @samp{-I} directories in the same order as they were
1441 specified (left to right) on the command line.
1444 @section Difference Tables: @option{-K}
1447 @ifclear DIFF-TBL-KLUGE
1448 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1449 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1450 where it can be used to warn when the assembler alters the machine code
1451 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1452 family does not have the addressing limitations that sometimes lead to this
1453 alteration on other platforms.
1456 @ifset DIFF-TBL-KLUGE
1457 @cindex difference tables, warning
1458 @cindex warning for altered difference tables
1459 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1460 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1461 You can use the @samp{-K} option if you want a warning issued when this
1466 @section Include Local Labels: @option{-L}
1469 @cindex local labels, retaining in output
1470 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1471 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1472 debugging, because they are intended for the use of programs (like
1473 compilers) that compose assembler programs, not for your notice.
1474 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1475 normally debug with them.
1477 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1478 in the object file. Usually if you do this you also tell the linker
1479 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1481 By default, a local label is any label beginning with @samp{L}, but each
1482 target is allowed to redefine the local label prefix.
1484 On the HPPA local labels begin with @samp{L$}.
1488 @section Configuring listing output: @option{--listing}
1490 The listing feature of the assembler can be enabled via the command line switch
1491 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1492 hex dump of the corresponding locations in the output object file, and displays
1493 them as a listing file. The format of this listing can be controlled by pseudo
1494 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1495 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1498 @item --listing-lhs-width=@samp{number}
1499 @kindex --listing-lhs-width
1500 @cindex Width of first line disassembly output
1501 Sets the maximum width, in words, of the first line of the hex byte dump. This
1502 dump appears on the left hand side of the listing output.
1504 @item --listing-lhs-width2=@samp{number}
1505 @kindex --listing-lhs-width2
1506 @cindex Width of continuation lines of disassembly output
1507 Sets the maximum width, in words, of any further lines of the hex byte dump for
1508 a given inut source line. If this value is not specified, it defaults to being
1509 the same as the value specified for @samp{--listing-lhs-width}. If neither
1510 switch is used the default is to one.
1512 @item --listing-rhs-width=@samp{number}
1513 @kindex --listing-rhs-width
1514 @cindex Width of source line output
1515 Sets the maximum width, in characters, of the source line that is displayed
1516 alongside the hex dump. The default value for this parameter is 100. The
1517 source line is displayed on the right hand side of the listing output.
1519 @item --listing-cont-lines=@samp{number}
1520 @kindex --listing-cont-lines
1521 @cindex Maximum number of continuation lines
1522 Sets the maximum number of continuation lines of hex dump that will be
1523 displayed for a given single line of source input. The default value is 4.
1527 @section Assemble in MRI Compatibility Mode: @option{-M}
1530 @cindex MRI compatibility mode
1531 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1532 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1533 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1534 configured target) assembler from Microtec Research. The exact nature of the
1535 MRI syntax will not be documented here; see the MRI manuals for more
1536 information. Note in particular that the handling of macros and macro
1537 arguments is somewhat different. The purpose of this option is to permit
1538 assembling existing MRI assembler code using @command{@value{AS}}.
1540 The MRI compatibility is not complete. Certain operations of the MRI assembler
1541 depend upon its object file format, and can not be supported using other object
1542 file formats. Supporting these would require enhancing each object file format
1543 individually. These are:
1546 @item global symbols in common section
1548 The m68k MRI assembler supports common sections which are merged by the linker.
1549 Other object file formats do not support this. @command{@value{AS}} handles
1550 common sections by treating them as a single common symbol. It permits local
1551 symbols to be defined within a common section, but it can not support global
1552 symbols, since it has no way to describe them.
1554 @item complex relocations
1556 The MRI assemblers support relocations against a negated section address, and
1557 relocations which combine the start addresses of two or more sections. These
1558 are not support by other object file formats.
1560 @item @code{END} pseudo-op specifying start address
1562 The MRI @code{END} pseudo-op permits the specification of a start address.
1563 This is not supported by other object file formats. The start address may
1564 instead be specified using the @option{-e} option to the linker, or in a linker
1567 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1569 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1570 name to the output file. This is not supported by other object file formats.
1572 @item @code{ORG} pseudo-op
1574 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1575 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1576 which changes the location within the current section. Absolute sections are
1577 not supported by other object file formats. The address of a section may be
1578 assigned within a linker script.
1581 There are some other features of the MRI assembler which are not supported by
1582 @command{@value{AS}}, typically either because they are difficult or because they
1583 seem of little consequence. Some of these may be supported in future releases.
1587 @item EBCDIC strings
1589 EBCDIC strings are not supported.
1591 @item packed binary coded decimal
1593 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1594 and @code{DCB.P} pseudo-ops are not supported.
1596 @item @code{FEQU} pseudo-op
1598 The m68k @code{FEQU} pseudo-op is not supported.
1600 @item @code{NOOBJ} pseudo-op
1602 The m68k @code{NOOBJ} pseudo-op is not supported.
1604 @item @code{OPT} branch control options
1606 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1607 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1608 relaxes all branches, whether forward or backward, to an appropriate size, so
1609 these options serve no purpose.
1611 @item @code{OPT} list control options
1613 The following m68k @code{OPT} list control options are ignored: @code{C},
1614 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1615 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1617 @item other @code{OPT} options
1619 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1620 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1622 @item @code{OPT} @code{D} option is default
1624 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1625 @code{OPT NOD} may be used to turn it off.
1627 @item @code{XREF} pseudo-op.
1629 The m68k @code{XREF} pseudo-op is ignored.
1631 @item @code{.debug} pseudo-op
1633 The i960 @code{.debug} pseudo-op is not supported.
1635 @item @code{.extended} pseudo-op
1637 The i960 @code{.extended} pseudo-op is not supported.
1639 @item @code{.list} pseudo-op.
1641 The various options of the i960 @code{.list} pseudo-op are not supported.
1643 @item @code{.optimize} pseudo-op
1645 The i960 @code{.optimize} pseudo-op is not supported.
1647 @item @code{.output} pseudo-op
1649 The i960 @code{.output} pseudo-op is not supported.
1651 @item @code{.setreal} pseudo-op
1653 The i960 @code{.setreal} pseudo-op is not supported.
1658 @section Dependency tracking: @option{--MD}
1661 @cindex dependency tracking
1664 @command{@value{AS}} can generate a dependency file for the file it creates. This
1665 file consists of a single rule suitable for @code{make} describing the
1666 dependencies of the main source file.
1668 The rule is written to the file named in its argument.
1670 This feature is used in the automatic updating of makefiles.
1673 @section Name the Object File: @option{-o}
1676 @cindex naming object file
1677 @cindex object file name
1678 There is always one object file output when you run @command{@value{AS}}. By
1679 default it has the name
1682 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1696 You use this option (which takes exactly one filename) to give the
1697 object file a different name.
1699 Whatever the object file is called, @command{@value{AS}} overwrites any
1700 existing file of the same name.
1703 @section Join Data and Text Sections: @option{-R}
1706 @cindex data and text sections, joining
1707 @cindex text and data sections, joining
1708 @cindex joining text and data sections
1709 @cindex merging text and data sections
1710 @option{-R} tells @command{@value{AS}} to write the object file as if all
1711 data-section data lives in the text section. This is only done at
1712 the very last moment: your binary data are the same, but data
1713 section parts are relocated differently. The data section part of
1714 your object file is zero bytes long because all its bytes are
1715 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1717 When you specify @option{-R} it would be possible to generate shorter
1718 address displacements (because we do not have to cross between text and
1719 data section). We refrain from doing this simply for compatibility with
1720 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1723 When @command{@value{AS}} is configured for COFF output,
1724 this option is only useful if you use sections named @samp{.text} and
1729 @option{-R} is not supported for any of the HPPA targets. Using
1730 @option{-R} generates a warning from @command{@value{AS}}.
1734 @section Display Assembly Statistics: @option{--statistics}
1736 @kindex --statistics
1737 @cindex statistics, about assembly
1738 @cindex time, total for assembly
1739 @cindex space used, maximum for assembly
1740 Use @samp{--statistics} to display two statistics about the resources used by
1741 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1742 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1745 @node traditional-format
1746 @section Compatible output: @option{--traditional-format}
1748 @kindex --traditional-format
1749 For some targets, the output of @command{@value{AS}} is different in some ways
1750 from the output of some existing assembler. This switch requests
1751 @command{@value{AS}} to use the traditional format instead.
1753 For example, it disables the exception frame optimizations which
1754 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1757 @section Announce Version: @option{-v}
1761 @cindex assembler version
1762 @cindex version of assembler
1763 You can find out what version of as is running by including the
1764 option @samp{-v} (which you can also spell as @samp{-version}) on the
1768 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1770 @command{@value{AS}} should never give a warning or error message when
1771 assembling compiler output. But programs written by people often
1772 cause @command{@value{AS}} to give a warning that a particular assumption was
1773 made. All such warnings are directed to the standard error file.
1776 @kindex @samp{--no-warn}
1777 @cindex suppressing warnings
1778 @cindex warnings, suppressing
1779 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1780 This only affects the warning messages: it does not change any particular of
1781 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1784 @kindex @samp{--fatal-warnings}
1785 @cindex errors, caused by warnings
1786 @cindex warnings, causing error
1787 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1788 files that generate warnings to be in error.
1790 @kindex @samp{--warn}
1791 @cindex warnings, switching on
1792 You can switch these options off again by specifying @option{--warn}, which
1793 causes warnings to be output as usual.
1796 @section Generate Object File in Spite of Errors: @option{-Z}
1797 @cindex object file, after errors
1798 @cindex errors, continuing after
1799 After an error message, @command{@value{AS}} normally produces no output. If for
1800 some reason you are interested in object file output even after
1801 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1802 option. If there are any errors, @command{@value{AS}} continues anyways, and
1803 writes an object file after a final warning message of the form @samp{@var{n}
1804 errors, @var{m} warnings, generating bad object file.}
1809 @cindex machine-independent syntax
1810 @cindex syntax, machine-independent
1811 This chapter describes the machine-independent syntax allowed in a
1812 source file. @command{@value{AS}} syntax is similar to what many other
1813 assemblers use; it is inspired by the BSD 4.2
1818 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1822 * Preprocessing:: Preprocessing
1823 * Whitespace:: Whitespace
1824 * Comments:: Comments
1825 * Symbol Intro:: Symbols
1826 * Statements:: Statements
1827 * Constants:: Constants
1831 @section Preprocessing
1833 @cindex preprocessing
1834 The @command{@value{AS}} internal preprocessor:
1836 @cindex whitespace, removed by preprocessor
1838 adjusts and removes extra whitespace. It leaves one space or tab before
1839 the keywords on a line, and turns any other whitespace on the line into
1842 @cindex comments, removed by preprocessor
1844 removes all comments, replacing them with a single space, or an
1845 appropriate number of newlines.
1847 @cindex constants, converted by preprocessor
1849 converts character constants into the appropriate numeric values.
1852 It does not do macro processing, include file handling, or
1853 anything else you may get from your C compiler's preprocessor. You can
1854 do include file processing with the @code{.include} directive
1855 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1856 to get other ``CPP'' style preprocessing, by giving the input file a
1857 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1858 Output, gcc.info, Using GNU CC}.
1860 Excess whitespace, comments, and character constants
1861 cannot be used in the portions of the input text that are not
1864 @cindex turning preprocessing on and off
1865 @cindex preprocessing, turning on and off
1868 If the first line of an input file is @code{#NO_APP} or if you use the
1869 @samp{-f} option, whitespace and comments are not removed from the input file.
1870 Within an input file, you can ask for whitespace and comment removal in
1871 specific portions of the by putting a line that says @code{#APP} before the
1872 text that may contain whitespace or comments, and putting a line that says
1873 @code{#NO_APP} after this text. This feature is mainly intend to support
1874 @code{asm} statements in compilers whose output is otherwise free of comments
1881 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1882 Whitespace is used to separate symbols, and to make programs neater for
1883 people to read. Unless within character constants
1884 (@pxref{Characters,,Character Constants}), any whitespace means the same
1885 as exactly one space.
1891 There are two ways of rendering comments to @command{@value{AS}}. In both
1892 cases the comment is equivalent to one space.
1894 Anything from @samp{/*} through the next @samp{*/} is a comment.
1895 This means you may not nest these comments.
1899 The only way to include a newline ('\n') in a comment
1900 is to use this sort of comment.
1903 /* This sort of comment does not nest. */
1906 @cindex line comment character
1907 Anything from the @dfn{line comment} character to the next newline
1908 is considered a comment and is ignored. The line comment character is
1910 @samp{;} for the AMD 29K family;
1913 @samp{;} on the ARC;
1916 @samp{@@} on the ARM;
1919 @samp{;} for the H8/300 family;
1922 @samp{!} for the H8/500 family;
1925 @samp{;} for the HPPA;
1928 @samp{#} on the i386 and x86-64;
1931 @samp{#} on the i960;
1934 @samp{;} for the PDP-11;
1937 @samp{;} for picoJava;
1940 @samp{;} for Motorola PowerPC;
1943 @samp{!} for the Hitachi SH;
1946 @samp{!} on the SPARC;
1949 @samp{#} on the m32r;
1952 @samp{|} on the 680x0;
1955 @samp{#} on the 68HC11 and 68HC12;
1958 @samp{;} on the M880x0;
1961 @samp{#} on the Vax;
1964 @samp{!} for the Z8000;
1967 @samp{#} on the V850;
1969 see @ref{Machine Dependencies}. @refill
1970 @c FIXME What about i860?
1973 On some machines there are two different line comment characters. One
1974 character only begins a comment if it is the first non-whitespace character on
1975 a line, while the other always begins a comment.
1979 The V850 assembler also supports a double dash as starting a comment that
1980 extends to the end of the line.
1986 @cindex lines starting with @code{#}
1987 @cindex logical line numbers
1988 To be compatible with past assemblers, lines that begin with @samp{#} have a
1989 special interpretation. Following the @samp{#} should be an absolute
1990 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1991 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1992 new logical file name. The rest of the line, if any, should be whitespace.
1994 If the first non-whitespace characters on the line are not numeric,
1995 the line is ignored. (Just like a comment.)
1998 # This is an ordinary comment.
1999 # 42-6 "new_file_name" # New logical file name
2000 # This is logical line # 36.
2002 This feature is deprecated, and may disappear from future versions
2003 of @command{@value{AS}}.
2008 @cindex characters used in symbols
2009 @ifclear SPECIAL-SYMS
2010 A @dfn{symbol} is one or more characters chosen from the set of all
2011 letters (both upper and lower case), digits and the three characters
2017 A @dfn{symbol} is one or more characters chosen from the set of all
2018 letters (both upper and lower case), digits and the three characters
2019 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2025 On most machines, you can also use @code{$} in symbol names; exceptions
2026 are noted in @ref{Machine Dependencies}.
2028 No symbol may begin with a digit. Case is significant.
2029 There is no length limit: all characters are significant. Symbols are
2030 delimited by characters not in that set, or by the beginning of a file
2031 (since the source program must end with a newline, the end of a file is
2032 not a possible symbol delimiter). @xref{Symbols}.
2033 @cindex length of symbols
2038 @cindex statements, structure of
2039 @cindex line separator character
2040 @cindex statement separator character
2042 @ifclear abnormal-separator
2043 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2044 semicolon (@samp{;}). The newline or semicolon is considered part of
2045 the preceding statement. Newlines and semicolons within character
2046 constants are an exception: they do not end statements.
2048 @ifset abnormal-separator
2050 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2051 sign (@samp{@@}). The newline or at sign is considered part of the
2052 preceding statement. Newlines and at signs within character constants
2053 are an exception: they do not end statements.
2056 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2057 point (@samp{!}). The newline or exclamation point is considered part of the
2058 preceding statement. Newlines and exclamation points within character
2059 constants are an exception: they do not end statements.
2062 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2063 H8/300) a dollar sign (@samp{$}); or (for the
2066 (@samp{;}). The newline or separator character is considered part of
2067 the preceding statement. Newlines and separators within character
2068 constants are an exception: they do not end statements.
2073 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2074 separator character. (The line separator is usually @samp{;}, unless
2075 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2076 newline or separator character is considered part of the preceding
2077 statement. Newlines and separators within character constants are an
2078 exception: they do not end statements.
2081 @cindex newline, required at file end
2082 @cindex EOF, newline must precede
2083 It is an error to end any statement with end-of-file: the last
2084 character of any input file should be a newline.@refill
2086 An empty statement is allowed, and may include whitespace. It is ignored.
2088 @cindex instructions and directives
2089 @cindex directives and instructions
2090 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2091 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2093 A statement begins with zero or more labels, optionally followed by a
2094 key symbol which determines what kind of statement it is. The key
2095 symbol determines the syntax of the rest of the statement. If the
2096 symbol begins with a dot @samp{.} then the statement is an assembler
2097 directive: typically valid for any computer. If the symbol begins with
2098 a letter the statement is an assembly language @dfn{instruction}: it
2099 assembles into a machine language instruction.
2101 Different versions of @command{@value{AS}} for different computers
2102 recognize different instructions. In fact, the same symbol may
2103 represent a different instruction in a different computer's assembly
2107 @cindex @code{:} (label)
2108 @cindex label (@code{:})
2109 A label is a symbol immediately followed by a colon (@code{:}).
2110 Whitespace before a label or after a colon is permitted, but you may not
2111 have whitespace between a label's symbol and its colon. @xref{Labels}.
2114 For HPPA targets, labels need not be immediately followed by a colon, but
2115 the definition of a label must begin in column zero. This also implies that
2116 only one label may be defined on each line.
2120 label: .directive followed by something
2121 another_label: # This is an empty statement.
2122 instruction operand_1, operand_2, @dots{}
2129 A constant is a number, written so that its value is known by
2130 inspection, without knowing any context. Like this:
2133 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2134 .ascii "Ring the bell\7" # A string constant.
2135 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2136 .float 0f-314159265358979323846264338327\
2137 95028841971.693993751E-40 # - pi, a flonum.
2142 * Characters:: Character Constants
2143 * Numbers:: Number Constants
2147 @subsection Character Constants
2149 @cindex character constants
2150 @cindex constants, character
2151 There are two kinds of character constants. A @dfn{character} stands
2152 for one character in one byte and its value may be used in
2153 numeric expressions. String constants (properly called string
2154 @emph{literals}) are potentially many bytes and their values may not be
2155 used in arithmetic expressions.
2159 * Chars:: Characters
2163 @subsubsection Strings
2165 @cindex string constants
2166 @cindex constants, string
2167 A @dfn{string} is written between double-quotes. It may contain
2168 double-quotes or null characters. The way to get special characters
2169 into a string is to @dfn{escape} these characters: precede them with
2170 a backslash @samp{\} character. For example @samp{\\} represents
2171 one backslash: the first @code{\} is an escape which tells
2172 @command{@value{AS}} to interpret the second character literally as a backslash
2173 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2174 escape character). The complete list of escapes follows.
2176 @cindex escape codes, character
2177 @cindex character escape codes
2180 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2182 @cindex @code{\b} (backspace character)
2183 @cindex backspace (@code{\b})
2185 Mnemonic for backspace; for ASCII this is octal code 010.
2188 @c Mnemonic for EOText; for ASCII this is octal code 004.
2190 @cindex @code{\f} (formfeed character)
2191 @cindex formfeed (@code{\f})
2193 Mnemonic for FormFeed; for ASCII this is octal code 014.
2195 @cindex @code{\n} (newline character)
2196 @cindex newline (@code{\n})
2198 Mnemonic for newline; for ASCII this is octal code 012.
2201 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2203 @cindex @code{\r} (carriage return character)
2204 @cindex carriage return (@code{\r})
2206 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2209 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2210 @c other assemblers.
2212 @cindex @code{\t} (tab)
2213 @cindex tab (@code{\t})
2215 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2218 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2219 @c @item \x @var{digit} @var{digit} @var{digit}
2220 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2222 @cindex @code{\@var{ddd}} (octal character code)
2223 @cindex octal character code (@code{\@var{ddd}})
2224 @item \ @var{digit} @var{digit} @var{digit}
2225 An octal character code. The numeric code is 3 octal digits.
2226 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2227 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2229 @cindex @code{\@var{xd...}} (hex character code)
2230 @cindex hex character code (@code{\@var{xd...}})
2231 @item \@code{x} @var{hex-digits...}
2232 A hex character code. All trailing hex digits are combined. Either upper or
2233 lower case @code{x} works.
2235 @cindex @code{\\} (@samp{\} character)
2236 @cindex backslash (@code{\\})
2238 Represents one @samp{\} character.
2241 @c Represents one @samp{'} (accent acute) character.
2242 @c This is needed in single character literals
2243 @c (@xref{Characters,,Character Constants}.) to represent
2246 @cindex @code{\"} (doublequote character)
2247 @cindex doublequote (@code{\"})
2249 Represents one @samp{"} character. Needed in strings to represent
2250 this character, because an unescaped @samp{"} would end the string.
2252 @item \ @var{anything-else}
2253 Any other character when escaped by @kbd{\} gives a warning, but
2254 assembles as if the @samp{\} was not present. The idea is that if
2255 you used an escape sequence you clearly didn't want the literal
2256 interpretation of the following character. However @command{@value{AS}} has no
2257 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2258 code and warns you of the fact.
2261 Which characters are escapable, and what those escapes represent,
2262 varies widely among assemblers. The current set is what we think
2263 the BSD 4.2 assembler recognizes, and is a subset of what most C
2264 compilers recognize. If you are in doubt, do not use an escape
2268 @subsubsection Characters
2270 @cindex single character constant
2271 @cindex character, single
2272 @cindex constant, single character
2273 A single character may be written as a single quote immediately
2274 followed by that character. The same escapes apply to characters as
2275 to strings. So if you want to write the character backslash, you
2276 must write @kbd{'\\} where the first @code{\} escapes the second
2277 @code{\}. As you can see, the quote is an acute accent, not a
2278 grave accent. A newline
2280 @ifclear abnormal-separator
2281 (or semicolon @samp{;})
2283 @ifset abnormal-separator
2285 (or at sign @samp{@@})
2288 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2294 immediately following an acute accent is taken as a literal character
2295 and does not count as the end of a statement. The value of a character
2296 constant in a numeric expression is the machine's byte-wide code for
2297 that character. @command{@value{AS}} assumes your character code is ASCII:
2298 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2301 @subsection Number Constants
2303 @cindex constants, number
2304 @cindex number constants
2305 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2306 are stored in the target machine. @emph{Integers} are numbers that
2307 would fit into an @code{int} in the C language. @emph{Bignums} are
2308 integers, but they are stored in more than 32 bits. @emph{Flonums}
2309 are floating point numbers, described below.
2312 * Integers:: Integers
2317 * Bit Fields:: Bit Fields
2323 @subsubsection Integers
2325 @cindex constants, integer
2327 @cindex binary integers
2328 @cindex integers, binary
2329 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2330 the binary digits @samp{01}.
2332 @cindex octal integers
2333 @cindex integers, octal
2334 An octal integer is @samp{0} followed by zero or more of the octal
2335 digits (@samp{01234567}).
2337 @cindex decimal integers
2338 @cindex integers, decimal
2339 A decimal integer starts with a non-zero digit followed by zero or
2340 more digits (@samp{0123456789}).
2342 @cindex hexadecimal integers
2343 @cindex integers, hexadecimal
2344 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2345 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2347 Integers have the usual values. To denote a negative integer, use
2348 the prefix operator @samp{-} discussed under expressions
2349 (@pxref{Prefix Ops,,Prefix Operators}).
2352 @subsubsection Bignums
2355 @cindex constants, bignum
2356 A @dfn{bignum} has the same syntax and semantics as an integer
2357 except that the number (or its negative) takes more than 32 bits to
2358 represent in binary. The distinction is made because in some places
2359 integers are permitted while bignums are not.
2362 @subsubsection Flonums
2364 @cindex floating point numbers
2365 @cindex constants, floating point
2367 @cindex precision, floating point
2368 A @dfn{flonum} represents a floating point number. The translation is
2369 indirect: a decimal floating point number from the text is converted by
2370 @command{@value{AS}} to a generic binary floating point number of more than
2371 sufficient precision. This generic floating point number is converted
2372 to a particular computer's floating point format (or formats) by a
2373 portion of @command{@value{AS}} specialized to that computer.
2375 A flonum is written by writing (in order)
2380 (@samp{0} is optional on the HPPA.)
2384 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2386 @kbd{e} is recommended. Case is not important.
2388 @c FIXME: verify if flonum syntax really this vague for most cases
2389 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2390 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2393 On the H8/300, H8/500,
2395 and AMD 29K architectures, the letter must be
2396 one of the letters @samp{DFPRSX} (in upper or lower case).
2398 On the ARC, the letter must be one of the letters @samp{DFRS}
2399 (in upper or lower case).
2401 On the Intel 960 architecture, the letter must be
2402 one of the letters @samp{DFT} (in upper or lower case).
2404 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2408 One of the letters @samp{DFPRSX} (in upper or lower case).
2411 One of the letters @samp{DFRS} (in upper or lower case).
2414 One of the letters @samp{DFPRSX} (in upper or lower case).
2417 The letter @samp{E} (upper case only).
2420 One of the letters @samp{DFT} (in upper or lower case).
2425 An optional sign: either @samp{+} or @samp{-}.
2428 An optional @dfn{integer part}: zero or more decimal digits.
2431 An optional @dfn{fractional part}: @samp{.} followed by zero
2432 or more decimal digits.
2435 An optional exponent, consisting of:
2439 An @samp{E} or @samp{e}.
2440 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2441 @c principle this can perfectly well be different on different targets.
2443 Optional sign: either @samp{+} or @samp{-}.
2445 One or more decimal digits.
2450 At least one of the integer part or the fractional part must be
2451 present. The floating point number has the usual base-10 value.
2453 @command{@value{AS}} does all processing using integers. Flonums are computed
2454 independently of any floating point hardware in the computer running
2455 @command{@value{AS}}.
2459 @c Bit fields are written as a general facility but are also controlled
2460 @c by a conditional-compilation flag---which is as of now (21mar91)
2461 @c turned on only by the i960 config of GAS.
2463 @subsubsection Bit Fields
2466 @cindex constants, bit field
2467 You can also define numeric constants as @dfn{bit fields}.
2468 specify two numbers separated by a colon---
2470 @var{mask}:@var{value}
2473 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2476 The resulting number is then packed
2478 @c this conditional paren in case bit fields turned on elsewhere than 960
2479 (in host-dependent byte order)
2481 into a field whose width depends on which assembler directive has the
2482 bit-field as its argument. Overflow (a result from the bitwise and
2483 requiring more binary digits to represent) is not an error; instead,
2484 more constants are generated, of the specified width, beginning with the
2485 least significant digits.@refill
2487 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2488 @code{.short}, and @code{.word} accept bit-field arguments.
2493 @chapter Sections and Relocation
2498 * Secs Background:: Background
2499 * Ld Sections:: Linker Sections
2500 * As Sections:: Assembler Internal Sections
2501 * Sub-Sections:: Sub-Sections
2505 @node Secs Background
2508 Roughly, a section is a range of addresses, with no gaps; all data
2509 ``in'' those addresses is treated the same for some particular purpose.
2510 For example there may be a ``read only'' section.
2512 @cindex linker, and assembler
2513 @cindex assembler, and linker
2514 The linker @code{@value{LD}} reads many object files (partial programs) and
2515 combines their contents to form a runnable program. When @command{@value{AS}}
2516 emits an object file, the partial program is assumed to start at address 0.
2517 @code{@value{LD}} assigns the final addresses for the partial program, so that
2518 different partial programs do not overlap. This is actually an
2519 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2522 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2523 addresses. These blocks slide to their run-time addresses as rigid
2524 units; their length does not change and neither does the order of bytes
2525 within them. Such a rigid unit is called a @emph{section}. Assigning
2526 run-time addresses to sections is called @dfn{relocation}. It includes
2527 the task of adjusting mentions of object-file addresses so they refer to
2528 the proper run-time addresses.
2530 For the H8/300 and H8/500,
2531 and for the Hitachi SH,
2532 @command{@value{AS}} pads sections if needed to
2533 ensure they end on a word (sixteen bit) boundary.
2536 @cindex standard assembler sections
2537 An object file written by @command{@value{AS}} has at least three sections, any
2538 of which may be empty. These are named @dfn{text}, @dfn{data} and
2543 When it generates COFF output,
2545 @command{@value{AS}} can also generate whatever other named sections you specify
2546 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2547 If you do not use any directives that place output in the @samp{.text}
2548 or @samp{.data} sections, these sections still exist, but are empty.
2553 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2555 @command{@value{AS}} can also generate whatever other named sections you
2556 specify using the @samp{.space} and @samp{.subspace} directives. See
2557 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2558 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2559 assembler directives.
2562 Additionally, @command{@value{AS}} uses different names for the standard
2563 text, data, and bss sections when generating SOM output. Program text
2564 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2565 BSS into @samp{$BSS$}.
2569 Within the object file, the text section starts at address @code{0}, the
2570 data section follows, and the bss section follows the data section.
2573 When generating either SOM or ELF output files on the HPPA, the text
2574 section starts at address @code{0}, the data section at address
2575 @code{0x4000000}, and the bss section follows the data section.
2578 To let @code{@value{LD}} know which data changes when the sections are
2579 relocated, and how to change that data, @command{@value{AS}} also writes to the
2580 object file details of the relocation needed. To perform relocation
2581 @code{@value{LD}} must know, each time an address in the object
2585 Where in the object file is the beginning of this reference to
2588 How long (in bytes) is this reference?
2590 Which section does the address refer to? What is the numeric value of
2592 (@var{address}) @minus{} (@var{start-address of section})?
2595 Is the reference to an address ``Program-Counter relative''?
2598 @cindex addresses, format of
2599 @cindex section-relative addressing
2600 In fact, every address @command{@value{AS}} ever uses is expressed as
2602 (@var{section}) + (@var{offset into section})
2605 Further, most expressions @command{@value{AS}} computes have this section-relative
2608 (For some object formats, such as SOM for the HPPA, some expressions are
2609 symbol-relative instead.)
2612 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2613 @var{N} into section @var{secname}.''
2615 Apart from text, data and bss sections you need to know about the
2616 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2617 addresses in the absolute section remain unchanged. For example, address
2618 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2619 @code{@value{LD}}. Although the linker never arranges two partial programs'
2620 data sections with overlapping addresses after linking, @emph{by definition}
2621 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2622 part of a program is always the same address when the program is running as
2623 address @code{@{absolute@ 239@}} in any other part of the program.
2625 The idea of sections is extended to the @dfn{undefined} section. Any
2626 address whose section is unknown at assembly time is by definition
2627 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2628 Since numbers are always defined, the only way to generate an undefined
2629 address is to mention an undefined symbol. A reference to a named
2630 common block would be such a symbol: its value is unknown at assembly
2631 time so it has section @emph{undefined}.
2633 By analogy the word @emph{section} is used to describe groups of sections in
2634 the linked program. @code{@value{LD}} puts all partial programs' text
2635 sections in contiguous addresses in the linked program. It is
2636 customary to refer to the @emph{text section} of a program, meaning all
2637 the addresses of all partial programs' text sections. Likewise for
2638 data and bss sections.
2640 Some sections are manipulated by @code{@value{LD}}; others are invented for
2641 use of @command{@value{AS}} and have no meaning except during assembly.
2644 @section Linker Sections
2645 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2650 @cindex named sections
2651 @cindex sections, named
2652 @item named sections
2655 @cindex text section
2656 @cindex data section
2660 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2661 separate but equal sections. Anything you can say of one section is
2664 When the program is running, however, it is
2665 customary for the text section to be unalterable. The
2666 text section is often shared among processes: it contains
2667 instructions, constants and the like. The data section of a running
2668 program is usually alterable: for example, C variables would be stored
2669 in the data section.
2674 This section contains zeroed bytes when your program begins running. It
2675 is used to hold uninitialized variables or common storage. The length of
2676 each partial program's bss section is important, but because it starts
2677 out containing zeroed bytes there is no need to store explicit zero
2678 bytes in the object file. The bss section was invented to eliminate
2679 those explicit zeros from object files.
2681 @cindex absolute section
2682 @item absolute section
2683 Address 0 of this section is always ``relocated'' to runtime address 0.
2684 This is useful if you want to refer to an address that @code{@value{LD}} must
2685 not change when relocating. In this sense we speak of absolute
2686 addresses being ``unrelocatable'': they do not change during relocation.
2688 @cindex undefined section
2689 @item undefined section
2690 This ``section'' is a catch-all for address references to objects not in
2691 the preceding sections.
2692 @c FIXME: ref to some other doc on obj-file formats could go here.
2695 @cindex relocation example
2696 An idealized example of three relocatable sections follows.
2698 The example uses the traditional section names @samp{.text} and @samp{.data}.
2700 Memory addresses are on the horizontal axis.
2704 @c END TEXI2ROFF-KILL
2707 partial program # 1: |ttttt|dddd|00|
2714 partial program # 2: |TTT|DDD|000|
2717 +--+---+-----+--+----+---+-----+~~
2718 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2719 +--+---+-----+--+----+---+-----+~~
2721 addresses: 0 @dots{}
2728 \line{\it Partial program \#1: \hfil}
2729 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2730 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2732 \line{\it Partial program \#2: \hfil}
2733 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2734 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2736 \line{\it linked program: \hfil}
2737 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2738 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2739 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2740 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2742 \line{\it addresses: \hfil}
2746 @c END TEXI2ROFF-KILL
2749 @section Assembler Internal Sections
2751 @cindex internal assembler sections
2752 @cindex sections in messages, internal
2753 These sections are meant only for the internal use of @command{@value{AS}}. They
2754 have no meaning at run-time. You do not really need to know about these
2755 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2756 warning messages, so it might be helpful to have an idea of their
2757 meanings to @command{@value{AS}}. These sections are used to permit the
2758 value of every expression in your assembly language program to be a
2759 section-relative address.
2762 @cindex assembler internal logic error
2763 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2764 An internal assembler logic error has been found. This means there is a
2765 bug in the assembler.
2767 @cindex expr (internal section)
2769 The assembler stores complex expression internally as combinations of
2770 symbols. When it needs to represent an expression as a symbol, it puts
2771 it in the expr section.
2773 @c FIXME item transfer[t] vector preload
2774 @c FIXME item transfer[t] vector postload
2775 @c FIXME item register
2779 @section Sub-Sections
2781 @cindex numbered subsections
2782 @cindex grouping data
2788 fall into two sections: text and data.
2790 You may have separate groups of
2792 data in named sections
2796 data in named sections
2802 that you want to end up near to each other in the object file, even though they
2803 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2804 use @dfn{subsections} for this purpose. Within each section, there can be
2805 numbered subsections with values from 0 to 8192. Objects assembled into the
2806 same subsection go into the object file together with other objects in the same
2807 subsection. For example, a compiler might want to store constants in the text
2808 section, but might not want to have them interspersed with the program being
2809 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2810 section of code being output, and a @samp{.text 1} before each group of
2811 constants being output.
2813 Subsections are optional. If you do not use subsections, everything
2814 goes in subsection number zero.
2817 Each subsection is zero-padded up to a multiple of four bytes.
2818 (Subsections may be padded a different amount on different flavors
2819 of @command{@value{AS}}.)
2823 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2824 boundary (two bytes).
2825 The same is true on the Hitachi SH.
2828 @c FIXME section padding (alignment)?
2829 @c Rich Pixley says padding here depends on target obj code format; that
2830 @c doesn't seem particularly useful to say without further elaboration,
2831 @c so for now I say nothing about it. If this is a generic BFD issue,
2832 @c these paragraphs might need to vanish from this manual, and be
2833 @c discussed in BFD chapter of binutils (or some such).
2836 On the AMD 29K family, no particular padding is added to section or
2837 subsection sizes; @value{AS} forces no alignment on this platform.
2841 Subsections appear in your object file in numeric order, lowest numbered
2842 to highest. (All this to be compatible with other people's assemblers.)
2843 The object file contains no representation of subsections; @code{@value{LD}} and
2844 other programs that manipulate object files see no trace of them.
2845 They just see all your text subsections as a text section, and all your
2846 data subsections as a data section.
2848 To specify which subsection you want subsequent statements assembled
2849 into, use a numeric argument to specify it, in a @samp{.text
2850 @var{expression}} or a @samp{.data @var{expression}} statement.
2853 When generating COFF output, you
2858 can also use an extra subsection
2859 argument with arbitrary named sections: @samp{.section @var{name},
2862 @var{Expression} should be an absolute expression.
2863 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2864 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2865 begins in @code{text 0}. For instance:
2867 .text 0 # The default subsection is text 0 anyway.
2868 .ascii "This lives in the first text subsection. *"
2870 .ascii "But this lives in the second text subsection."
2872 .ascii "This lives in the data section,"
2873 .ascii "in the first data subsection."
2875 .ascii "This lives in the first text section,"
2876 .ascii "immediately following the asterisk (*)."
2879 Each section has a @dfn{location counter} incremented by one for every byte
2880 assembled into that section. Because subsections are merely a convenience
2881 restricted to @command{@value{AS}} there is no concept of a subsection location
2882 counter. There is no way to directly manipulate a location counter---but the
2883 @code{.align} directive changes it, and any label definition captures its
2884 current value. The location counter of the section where statements are being
2885 assembled is said to be the @dfn{active} location counter.
2888 @section bss Section
2891 @cindex common variable storage
2892 The bss section is used for local common variable storage.
2893 You may allocate address space in the bss section, but you may
2894 not dictate data to load into it before your program executes. When
2895 your program starts running, all the contents of the bss
2896 section are zeroed bytes.
2898 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2899 @ref{Lcomm,,@code{.lcomm}}.
2901 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2902 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2905 When assembling for a target which supports multiple sections, such as ELF or
2906 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2907 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2908 section. Typically the section will only contain symbol definitions and
2909 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2916 Symbols are a central concept: the programmer uses symbols to name
2917 things, the linker uses symbols to link, and the debugger uses symbols
2921 @cindex debuggers, and symbol order
2922 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2923 the same order they were declared. This may break some debuggers.
2928 * Setting Symbols:: Giving Symbols Other Values
2929 * Symbol Names:: Symbol Names
2930 * Dot:: The Special Dot Symbol
2931 * Symbol Attributes:: Symbol Attributes
2938 A @dfn{label} is written as a symbol immediately followed by a colon
2939 @samp{:}. The symbol then represents the current value of the
2940 active location counter, and is, for example, a suitable instruction
2941 operand. You are warned if you use the same symbol to represent two
2942 different locations: the first definition overrides any other
2946 On the HPPA, the usual form for a label need not be immediately followed by a
2947 colon, but instead must start in column zero. Only one label may be defined on
2948 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2949 provides a special directive @code{.label} for defining labels more flexibly.
2952 @node Setting Symbols
2953 @section Giving Symbols Other Values
2955 @cindex assigning values to symbols
2956 @cindex symbol values, assigning
2957 A symbol can be given an arbitrary value by writing a symbol, followed
2958 by an equals sign @samp{=}, followed by an expression
2959 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2960 directive. @xref{Set,,@code{.set}}.
2963 @section Symbol Names
2965 @cindex symbol names
2966 @cindex names, symbol
2967 @ifclear SPECIAL-SYMS
2968 Symbol names begin with a letter or with one of @samp{._}. On most
2969 machines, you can also use @code{$} in symbol names; exceptions are
2970 noted in @ref{Machine Dependencies}. That character may be followed by any
2971 string of digits, letters, dollar signs (unless otherwise noted in
2972 @ref{Machine Dependencies}), and underscores.
2975 For the AMD 29K family, @samp{?} is also allowed in the
2976 body of a symbol name, though not at its beginning.
2981 Symbol names begin with a letter or with one of @samp{._}. On the
2983 H8/500, you can also use @code{$} in symbol names. That character may
2984 be followed by any string of digits, letters, dollar signs (save on the
2985 H8/300), and underscores.
2989 Case of letters is significant: @code{foo} is a different symbol name
2992 Each symbol has exactly one name. Each name in an assembly language program
2993 refers to exactly one symbol. You may use that symbol name any number of times
2996 @subheading Local Symbol Names
2998 @cindex local symbol names
2999 @cindex symbol names, local
3000 @cindex temporary symbol names
3001 @cindex symbol names, temporary
3002 Local symbols help compilers and programmers use names temporarily.
3003 They create symbols which are guaranteed to be unique over the entire scope of
3004 the input source code and which can be referred to by a simple notation.
3005 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3006 represents any positive integer). To refer to the most recent previous
3007 definition of that symbol write @samp{@b{N}b}, using the same number as when
3008 you defined the label. To refer to the next definition of a local label, write
3009 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3012 There is no restriction on how you can use these labels, and you can reuse them
3013 too. So that it is possible to repeatedly define the same local label (using
3014 the same number @samp{@b{N}}), although you can only refer to the most recently
3015 defined local label of that number (for a backwards reference) or the next
3016 definition of a specific local label for a forward reference. It is also worth
3017 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3018 implemented in a slightly more efficient manner than the others.
3029 Which is the equivalent of:
3032 label_1: branch label_3
3033 label_2: branch label_1
3034 label_3: branch label_4
3035 label_4: branch label_3
3038 Local symbol names are only a notational device. They are immediately
3039 transformed into more conventional symbol names before the assembler uses them.
3040 The symbol names stored in the symbol table, appearing in error messages and
3041 optionally emitted to the object file. The names are constructed using these
3046 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3047 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3048 used for symbols you are never intended to see. If you use the
3049 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3050 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3051 you may use them in debugging.
3054 This is the number that was used in the local label definition. So if the
3055 label is written @samp{55:} then the number is @samp{55}.
3058 This unusual character is included so you do not accidentally invent a symbol
3059 of the same name. The character has ASCII value of @samp{\002} (control-B).
3061 @item @emph{ordinal number}
3062 This is a serial number to keep the labels distinct. The first definition of
3063 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3064 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3065 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3068 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3069 @code{3:} is named @code{L3@kbd{C-B}44}.
3071 @subheading Dollar Local Labels
3072 @cindex dollar local symbols
3074 @code{@value{AS}} also supports an even more local form of local labels called
3075 dollar labels. These labels go out of scope (ie they become undefined) as soon
3076 as a non-local label is defined. Thus they remain valid for only a small
3077 region of the input source code. Normal local labels, by contrast, remain in
3078 scope for the entire file, or until they are redefined by another occurrence of
3079 the same local label.
3081 Dollar labels are defined in exactly the same way as ordinary local labels,
3082 except that instead of being terminated by a colon, they are terminated by a
3083 dollar sign. eg @samp{@b{55$}}.
3085 They can also be distinguished from ordinary local labels by their transformed
3086 name which uses ASCII character @samp{\001} (control-A) as the magic character
3087 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3088 is named @samp{L6@kbd{C-A}5}.
3091 @section The Special Dot Symbol
3093 @cindex dot (symbol)
3094 @cindex @code{.} (symbol)
3095 @cindex current address
3096 @cindex location counter
3097 The special symbol @samp{.} refers to the current address that
3098 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3099 .long .} defines @code{melvin} to contain its own address.
3100 Assigning a value to @code{.} is treated the same as a @code{.org}
3101 directive. Thus, the expression @samp{.=.+4} is the same as saying
3102 @ifclear no-space-dir
3111 @node Symbol Attributes
3112 @section Symbol Attributes
3114 @cindex symbol attributes
3115 @cindex attributes, symbol
3116 Every symbol has, as well as its name, the attributes ``Value'' and
3117 ``Type''. Depending on output format, symbols can also have auxiliary
3120 The detailed definitions are in @file{a.out.h}.
3123 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3124 all these attributes, and probably won't warn you. This makes the
3125 symbol an externally defined symbol, which is generally what you
3129 * Symbol Value:: Value
3130 * Symbol Type:: Type
3133 * a.out Symbols:: Symbol Attributes: @code{a.out}
3137 * a.out Symbols:: Symbol Attributes: @code{a.out}
3140 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3145 * COFF Symbols:: Symbol Attributes for COFF
3148 * SOM Symbols:: Symbol Attributes for SOM
3155 @cindex value of a symbol
3156 @cindex symbol value
3157 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3158 location in the text, data, bss or absolute sections the value is the
3159 number of addresses from the start of that section to the label.
3160 Naturally for text, data and bss sections the value of a symbol changes
3161 as @code{@value{LD}} changes section base addresses during linking. Absolute
3162 symbols' values do not change during linking: that is why they are
3165 The value of an undefined symbol is treated in a special way. If it is
3166 0 then the symbol is not defined in this assembler source file, and
3167 @code{@value{LD}} tries to determine its value from other files linked into the
3168 same program. You make this kind of symbol simply by mentioning a symbol
3169 name without defining it. A non-zero value represents a @code{.comm}
3170 common declaration. The value is how much common storage to reserve, in
3171 bytes (addresses). The symbol refers to the first address of the
3177 @cindex type of a symbol
3179 The type attribute of a symbol contains relocation (section)
3180 information, any flag settings indicating that a symbol is external, and
3181 (optionally), other information for linkers and debuggers. The exact
3182 format depends on the object-code output format in use.
3187 @c The following avoids a "widow" subsection title. @group would be
3188 @c better if it were available outside examples.
3191 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3193 @cindex @code{b.out} symbol attributes
3194 @cindex symbol attributes, @code{b.out}
3195 These symbol attributes appear only when @command{@value{AS}} is configured for
3196 one of the Berkeley-descended object output formats---@code{a.out} or
3202 @subsection Symbol Attributes: @code{a.out}
3204 @cindex @code{a.out} symbol attributes
3205 @cindex symbol attributes, @code{a.out}
3211 @subsection Symbol Attributes: @code{a.out}
3213 @cindex @code{a.out} symbol attributes
3214 @cindex symbol attributes, @code{a.out}
3218 * Symbol Desc:: Descriptor
3219 * Symbol Other:: Other
3223 @subsubsection Descriptor
3225 @cindex descriptor, of @code{a.out} symbol
3226 This is an arbitrary 16-bit value. You may establish a symbol's
3227 descriptor value by using a @code{.desc} statement
3228 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3229 @command{@value{AS}}.
3232 @subsubsection Other
3234 @cindex other attribute, of @code{a.out} symbol
3235 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3240 @subsection Symbol Attributes for COFF
3242 @cindex COFF symbol attributes
3243 @cindex symbol attributes, COFF
3245 The COFF format supports a multitude of auxiliary symbol attributes;
3246 like the primary symbol attributes, they are set between @code{.def} and
3247 @code{.endef} directives.
3249 @subsubsection Primary Attributes
3251 @cindex primary attributes, COFF symbols
3252 The symbol name is set with @code{.def}; the value and type,
3253 respectively, with @code{.val} and @code{.type}.
3255 @subsubsection Auxiliary Attributes
3257 @cindex auxiliary attributes, COFF symbols
3258 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3259 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3260 information for COFF.
3265 @subsection Symbol Attributes for SOM
3267 @cindex SOM symbol attributes
3268 @cindex symbol attributes, SOM
3270 The SOM format for the HPPA supports a multitude of symbol attributes set with
3271 the @code{.EXPORT} and @code{.IMPORT} directives.
3273 The attributes are described in @cite{HP9000 Series 800 Assembly
3274 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3275 @code{EXPORT} assembler directive documentation.
3279 @chapter Expressions
3283 @cindex numeric values
3284 An @dfn{expression} specifies an address or numeric value.
3285 Whitespace may precede and/or follow an expression.
3287 The result of an expression must be an absolute number, or else an offset into
3288 a particular section. If an expression is not absolute, and there is not
3289 enough information when @command{@value{AS}} sees the expression to know its
3290 section, a second pass over the source program might be necessary to interpret
3291 the expression---but the second pass is currently not implemented.
3292 @command{@value{AS}} aborts with an error message in this situation.
3295 * Empty Exprs:: Empty Expressions
3296 * Integer Exprs:: Integer Expressions
3300 @section Empty Expressions
3302 @cindex empty expressions
3303 @cindex expressions, empty
3304 An empty expression has no value: it is just whitespace or null.
3305 Wherever an absolute expression is required, you may omit the
3306 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3307 is compatible with other assemblers.
3310 @section Integer Expressions
3312 @cindex integer expressions
3313 @cindex expressions, integer
3314 An @dfn{integer expression} is one or more @emph{arguments} delimited
3315 by @emph{operators}.
3318 * Arguments:: Arguments
3319 * Operators:: Operators
3320 * Prefix Ops:: Prefix Operators
3321 * Infix Ops:: Infix Operators
3325 @subsection Arguments
3327 @cindex expression arguments
3328 @cindex arguments in expressions
3329 @cindex operands in expressions
3330 @cindex arithmetic operands
3331 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3332 contexts arguments are sometimes called ``arithmetic operands''. In
3333 this manual, to avoid confusing them with the ``instruction operands'' of
3334 the machine language, we use the term ``argument'' to refer to parts of
3335 expressions only, reserving the word ``operand'' to refer only to machine
3336 instruction operands.
3338 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3339 @var{section} is one of text, data, bss, absolute,
3340 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3343 Numbers are usually integers.
3345 A number can be a flonum or bignum. In this case, you are warned
3346 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3347 these 32 bits are an integer. You may write integer-manipulating
3348 instructions that act on exotic constants, compatible with other
3351 @cindex subexpressions
3352 Subexpressions are a left parenthesis @samp{(} followed by an integer
3353 expression, followed by a right parenthesis @samp{)}; or a prefix
3354 operator followed by an argument.
3357 @subsection Operators
3359 @cindex operators, in expressions
3360 @cindex arithmetic functions
3361 @cindex functions, in expressions
3362 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3363 operators are followed by an argument. Infix operators appear
3364 between their arguments. Operators may be preceded and/or followed by
3368 @subsection Prefix Operator
3370 @cindex prefix operators
3371 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3372 one argument, which must be absolute.
3374 @c the tex/end tex stuff surrounding this small table is meant to make
3375 @c it align, on the printed page, with the similar table in the next
3376 @c section (which is inside an enumerate).
3378 \global\advance\leftskip by \itemindent
3383 @dfn{Negation}. Two's complement negation.
3385 @dfn{Complementation}. Bitwise not.
3389 \global\advance\leftskip by -\itemindent
3393 @subsection Infix Operators
3395 @cindex infix operators
3396 @cindex operators, permitted arguments
3397 @dfn{Infix operators} take two arguments, one on either side. Operators
3398 have precedence, but operations with equal precedence are performed left
3399 to right. Apart from @code{+} or @option{-}, both arguments must be
3400 absolute, and the result is absolute.
3403 @cindex operator precedence
3404 @cindex precedence of operators
3411 @dfn{Multiplication}.
3414 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3421 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3425 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3429 Intermediate precedence
3434 @dfn{Bitwise Inclusive Or}.
3440 @dfn{Bitwise Exclusive Or}.
3443 @dfn{Bitwise Or Not}.
3450 @cindex addition, permitted arguments
3451 @cindex plus, permitted arguments
3452 @cindex arguments for addition
3454 @dfn{Addition}. If either argument is absolute, the result has the section of
3455 the other argument. You may not add together arguments from different
3458 @cindex subtraction, permitted arguments
3459 @cindex minus, permitted arguments
3460 @cindex arguments for subtraction
3462 @dfn{Subtraction}. If the right argument is absolute, the
3463 result has the section of the left argument.
3464 If both arguments are in the same section, the result is absolute.
3465 You may not subtract arguments from different sections.
3466 @c FIXME is there still something useful to say about undefined - undefined ?
3468 @cindex comparison expressions
3469 @cindex expressions, comparison
3473 @dfn{Is Not Equal To}
3477 @dfn{Is Greater Than}
3479 @dfn{Is Greater Than Or Equal To}
3481 @dfn{Is Less Than Or Equal To}
3483 The comparison operators can be used as infix operators. A true results has a
3484 value of -1 whereas a false result has a value of 0. Note, these operators
3485 perform signed comparisons.
3488 @item Lowest Precedence
3497 These two logical operations can be used to combine the results of sub
3498 expressions. Note, unlike the comparison operators a true result returns a
3499 value of 1 but a false results does still return 0. Also note that the logical
3500 or operator has a slightly lower precedence than logical and.
3505 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3506 address; you can only have a defined section in one of the two arguments.
3509 @chapter Assembler Directives
3511 @cindex directives, machine independent
3512 @cindex pseudo-ops, machine independent
3513 @cindex machine independent directives
3514 All assembler directives have names that begin with a period (@samp{.}).
3515 The rest of the name is letters, usually in lower case.
3517 This chapter discusses directives that are available regardless of the
3518 target machine configuration for the @sc{gnu} assembler.
3520 Some machine configurations provide additional directives.
3521 @xref{Machine Dependencies}.
3524 @ifset machine-directives
3525 @xref{Machine Dependencies} for additional directives.
3530 * Abort:: @code{.abort}
3532 * ABORT:: @code{.ABORT}
3535 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3536 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3537 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3538 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3539 * Byte:: @code{.byte @var{expressions}}
3540 * Comm:: @code{.comm @var{symbol} , @var{length} }
3541 * Data:: @code{.data @var{subsection}}
3543 * Def:: @code{.def @var{name}}
3546 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3552 * Double:: @code{.double @var{flonums}}
3553 * Eject:: @code{.eject}
3554 * Else:: @code{.else}
3555 * Elseif:: @code{.elseif}
3558 * Endef:: @code{.endef}
3561 * Endfunc:: @code{.endfunc}
3562 * Endif:: @code{.endif}
3563 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3564 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3566 * Exitm:: @code{.exitm}
3567 * Extern:: @code{.extern}
3568 * Fail:: @code{.fail}
3569 @ifclear no-file-dir
3570 * File:: @code{.file @var{string}}
3573 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3574 * Float:: @code{.float @var{flonums}}
3575 * Func:: @code{.func}
3576 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3578 * Hidden:: @code{.hidden @var{names}}
3581 * hword:: @code{.hword @var{expressions}}
3582 * Ident:: @code{.ident}
3583 * If:: @code{.if @var{absolute expression}}
3584 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3585 * Include:: @code{.include "@var{file}"}
3586 * Int:: @code{.int @var{expressions}}
3588 * Internal:: @code{.internal @var{names}}
3591 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3592 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3593 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3594 * Lflags:: @code{.lflags}
3595 @ifclear no-line-dir
3596 * Line:: @code{.line @var{line-number}}
3599 * Ln:: @code{.ln @var{line-number}}
3600 * Linkonce:: @code{.linkonce [@var{type}]}
3601 * List:: @code{.list}
3602 * Long:: @code{.long @var{expressions}}
3604 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3607 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3608 * MRI:: @code{.mri @var{val}}
3609 * Nolist:: @code{.nolist}
3610 * Octa:: @code{.octa @var{bignums}}
3611 * Org:: @code{.org @var{new-lc} , @var{fill}}
3612 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3614 * PopSection:: @code{.popsection}
3615 * Previous:: @code{.previous}
3618 * Print:: @code{.print @var{string}}
3620 * Protected:: @code{.protected @var{names}}
3623 * Psize:: @code{.psize @var{lines}, @var{columns}}
3624 * Purgem:: @code{.purgem @var{name}}
3626 * PushSection:: @code{.pushsection @var{name}}
3629 * Quad:: @code{.quad @var{bignums}}
3630 * Rept:: @code{.rept @var{count}}
3631 * Sbttl:: @code{.sbttl "@var{subheading}"}
3633 * Scl:: @code{.scl @var{class}}
3634 * Section:: @code{.section @var{name}, @var{subsection}}
3637 * Set:: @code{.set @var{symbol}, @var{expression}}
3638 * Short:: @code{.short @var{expressions}}
3639 * Single:: @code{.single @var{flonums}}
3640 * Size:: @code{.size [@var{name} , @var{expression}]}
3641 * Skip:: @code{.skip @var{size} , @var{fill}}
3642 * Sleb128:: @code{.sleb128 @var{expressions}}
3643 * Space:: @code{.space @var{size} , @var{fill}}
3645 * Stab:: @code{.stabd, .stabn, .stabs}
3648 * String:: @code{.string "@var{str}"}
3649 * Struct:: @code{.struct @var{expression}}
3651 * SubSection:: @code{.subsection}
3652 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3656 * Tag:: @code{.tag @var{structname}}
3659 * Text:: @code{.text @var{subsection}}
3660 * Title:: @code{.title "@var{heading}"}
3661 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3662 * Uleb128:: @code{.uleb128 @var{expressions}}
3664 * Val:: @code{.val @var{addr}}
3668 * Version:: @code{.version "@var{string}"}
3669 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3670 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3671 * Weak:: @code{.weak @var{names}}
3674 * Word:: @code{.word @var{expressions}}
3675 * Deprecated:: Deprecated Directives
3679 @section @code{.abort}
3681 @cindex @code{abort} directive
3682 @cindex stopping the assembly
3683 This directive stops the assembly immediately. It is for
3684 compatibility with other assemblers. The original idea was that the
3685 assembly language source would be piped into the assembler. If the sender
3686 of the source quit, it could use this directive tells @command{@value{AS}} to
3687 quit also. One day @code{.abort} will not be supported.
3691 @section @code{.ABORT}
3693 @cindex @code{ABORT} directive
3694 When producing COFF output, @command{@value{AS}} accepts this directive as a
3695 synonym for @samp{.abort}.
3698 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3704 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3706 @cindex padding the location counter
3707 @cindex @code{align} directive
3708 Pad the location counter (in the current subsection) to a particular storage
3709 boundary. The first expression (which must be absolute) is the alignment
3710 required, as described below.
3712 The second expression (also absolute) gives the fill value to be stored in the
3713 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3714 padding bytes are normally zero. However, on some systems, if the section is
3715 marked as containing code and the fill value is omitted, the space is filled
3716 with no-op instructions.
3718 The third expression is also absolute, and is also optional. If it is present,
3719 it is the maximum number of bytes that should be skipped by this alignment
3720 directive. If doing the alignment would require skipping more bytes than the
3721 specified maximum, then the alignment is not done at all. You can omit the
3722 fill value (the second argument) entirely by simply using two commas after the
3723 required alignment; this can be useful if you want the alignment to be filled
3724 with no-op instructions when appropriate.
3726 The way the required alignment is specified varies from system to system.
3727 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3729 the first expression is the
3730 alignment request in bytes. For example @samp{.align 8} advances
3731 the location counter until it is a multiple of 8. If the location counter
3732 is already a multiple of 8, no change is needed.
3734 For other systems, including the i386 using a.out format, and the arm and
3735 strongarm, it is the
3736 number of low-order zero bits the location counter must have after
3737 advancement. For example @samp{.align 3} advances the location
3738 counter until it a multiple of 8. If the location counter is already a
3739 multiple of 8, no change is needed.
3741 This inconsistency is due to the different behaviors of the various
3742 native assemblers for these systems which GAS must emulate.
3743 GAS also provides @code{.balign} and @code{.p2align} directives,
3744 described later, which have a consistent behavior across all
3745 architectures (but are specific to GAS).
3748 @section @code{.ascii "@var{string}"}@dots{}
3750 @cindex @code{ascii} directive
3751 @cindex string literals
3752 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3753 separated by commas. It assembles each string (with no automatic
3754 trailing zero byte) into consecutive addresses.
3757 @section @code{.asciz "@var{string}"}@dots{}
3759 @cindex @code{asciz} directive
3760 @cindex zero-terminated strings
3761 @cindex null-terminated strings
3762 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3763 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3766 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3768 @cindex padding the location counter given number of bytes
3769 @cindex @code{balign} directive
3770 Pad the location counter (in the current subsection) to a particular
3771 storage boundary. The first expression (which must be absolute) is the
3772 alignment request in bytes. For example @samp{.balign 8} advances
3773 the location counter until it is a multiple of 8. If the location counter
3774 is already a multiple of 8, no change is needed.
3776 The second expression (also absolute) gives the fill value to be stored in the
3777 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3778 padding bytes are normally zero. However, on some systems, if the section is
3779 marked as containing code and the fill value is omitted, the space is filled
3780 with no-op instructions.
3782 The third expression is also absolute, and is also optional. If it is present,
3783 it is the maximum number of bytes that should be skipped by this alignment
3784 directive. If doing the alignment would require skipping more bytes than the
3785 specified maximum, then the alignment is not done at all. You can omit the
3786 fill value (the second argument) entirely by simply using two commas after the
3787 required alignment; this can be useful if you want the alignment to be filled
3788 with no-op instructions when appropriate.
3790 @cindex @code{balignw} directive
3791 @cindex @code{balignl} directive
3792 The @code{.balignw} and @code{.balignl} directives are variants of the
3793 @code{.balign} directive. The @code{.balignw} directive treats the fill
3794 pattern as a two byte word value. The @code{.balignl} directives treats the
3795 fill pattern as a four byte longword value. For example, @code{.balignw
3796 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3797 filled in with the value 0x368d (the exact placement of the bytes depends upon
3798 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3802 @section @code{.byte @var{expressions}}
3804 @cindex @code{byte} directive
3805 @cindex integers, one byte
3806 @code{.byte} expects zero or more expressions, separated by commas.
3807 Each expression is assembled into the next byte.
3810 @section @code{.comm @var{symbol} , @var{length} }
3812 @cindex @code{comm} directive
3813 @cindex symbol, common
3814 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3815 common symbol in one object file may be merged with a defined or common symbol
3816 of the same name in another object file. If @code{@value{LD}} does not see a
3817 definition for the symbol--just one or more common symbols--then it will
3818 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3819 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3820 the same name, and they do not all have the same size, it will allocate space
3821 using the largest size.
3824 When using ELF, the @code{.comm} directive takes an optional third argument.
3825 This is the desired alignment of the symbol, specified as a byte boundary (for
3826 example, an alignment of 16 means that the least significant 4 bits of the
3827 address should be zero). The alignment must be an absolute expression, and it
3828 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3829 for the common symbol, it will use the alignment when placing the symbol. If
3830 no alignment is specified, @command{@value{AS}} will set the alignment to the
3831 largest power of two less than or equal to the size of the symbol, up to a
3836 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3837 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3841 @section @code{.data @var{subsection}}
3843 @cindex @code{data} directive
3844 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3845 end of the data subsection numbered @var{subsection} (which is an
3846 absolute expression). If @var{subsection} is omitted, it defaults
3851 @section @code{.def @var{name}}
3853 @cindex @code{def} directive
3854 @cindex COFF symbols, debugging
3855 @cindex debugging COFF symbols
3856 Begin defining debugging information for a symbol @var{name}; the
3857 definition extends until the @code{.endef} directive is encountered.
3860 This directive is only observed when @command{@value{AS}} is configured for COFF
3861 format output; when producing @code{b.out}, @samp{.def} is recognized,
3868 @section @code{.desc @var{symbol}, @var{abs-expression}}
3870 @cindex @code{desc} directive
3871 @cindex COFF symbol descriptor
3872 @cindex symbol descriptor, COFF
3873 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3874 to the low 16 bits of an absolute expression.
3877 The @samp{.desc} directive is not available when @command{@value{AS}} is
3878 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3879 object format. For the sake of compatibility, @command{@value{AS}} accepts
3880 it, but produces no output, when configured for COFF.
3886 @section @code{.dim}
3888 @cindex @code{dim} directive
3889 @cindex COFF auxiliary symbol information
3890 @cindex auxiliary symbol information, COFF
3891 This directive is generated by compilers to include auxiliary debugging
3892 information in the symbol table. It is only permitted inside
3893 @code{.def}/@code{.endef} pairs.
3896 @samp{.dim} is only meaningful when generating COFF format output; when
3897 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3903 @section @code{.double @var{flonums}}
3905 @cindex @code{double} directive
3906 @cindex floating point numbers (double)
3907 @code{.double} expects zero or more flonums, separated by commas. It
3908 assembles floating point numbers.
3910 The exact kind of floating point numbers emitted depends on how
3911 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3915 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3916 in @sc{ieee} format.
3921 @section @code{.eject}
3923 @cindex @code{eject} directive
3924 @cindex new page, in listings
3925 @cindex page, in listings
3926 @cindex listing control: new page
3927 Force a page break at this point, when generating assembly listings.
3930 @section @code{.else}
3932 @cindex @code{else} directive
3933 @code{.else} is part of the @command{@value{AS}} support for conditional
3934 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3935 of code to be assembled if the condition for the preceding @code{.if}
3939 @section @code{.elseif}
3941 @cindex @code{elseif} directive
3942 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3943 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3944 @code{.if} block that would otherwise fill the entire @code{.else} section.
3947 @section @code{.end}
3949 @cindex @code{end} directive
3950 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3951 process anything in the file past the @code{.end} directive.
3955 @section @code{.endef}
3957 @cindex @code{endef} directive
3958 This directive flags the end of a symbol definition begun with
3962 @samp{.endef} is only meaningful when generating COFF format output; if
3963 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3964 directive but ignores it.
3969 @section @code{.endfunc}
3970 @cindex @code{endfunc} directive
3971 @code{.endfunc} marks the end of a function specified with @code{.func}.
3974 @section @code{.endif}
3976 @cindex @code{endif} directive
3977 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3978 it marks the end of a block of code that is only assembled
3979 conditionally. @xref{If,,@code{.if}}.
3982 @section @code{.equ @var{symbol}, @var{expression}}
3984 @cindex @code{equ} directive
3985 @cindex assigning values to symbols
3986 @cindex symbols, assigning values to
3987 This directive sets the value of @var{symbol} to @var{expression}.
3988 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3991 The syntax for @code{equ} on the HPPA is
3992 @samp{@var{symbol} .equ @var{expression}}.
3996 @section @code{.equiv @var{symbol}, @var{expression}}
3997 @cindex @code{equiv} directive
3998 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3999 the assembler will signal an error if @var{symbol} is already defined.
4001 Except for the contents of the error message, this is roughly equivalent to
4010 @section @code{.err}
4011 @cindex @code{err} directive
4012 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4013 message and, unless the @option{-Z} option was used, it will not generate an
4014 object file. This can be used to signal error an conditionally compiled code.
4017 @section @code{.exitm}
4018 Exit early from the current macro definition. @xref{Macro}.
4021 @section @code{.extern}
4023 @cindex @code{extern} directive
4024 @code{.extern} is accepted in the source program---for compatibility
4025 with other assemblers---but it is ignored. @command{@value{AS}} treats
4026 all undefined symbols as external.
4029 @section @code{.fail @var{expression}}
4031 @cindex @code{fail} directive
4032 Generates an error or a warning. If the value of the @var{expression} is 500
4033 or more, @command{@value{AS}} will print a warning message. If the value is less
4034 than 500, @command{@value{AS}} will print an error message. The message will
4035 include the value of @var{expression}. This can occasionally be useful inside
4036 complex nested macros or conditional assembly.
4038 @ifclear no-file-dir
4040 @section @code{.file @var{string}}
4042 @cindex @code{file} directive
4043 @cindex logical file name
4044 @cindex file name, logical
4045 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4046 file. @var{string} is the new file name. In general, the filename is
4047 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4048 to specify an empty file name, you must give the quotes--@code{""}. This
4049 statement may go away in future: it is only recognized to be compatible with
4050 old @command{@value{AS}} programs.
4052 In some configurations of @command{@value{AS}}, @code{.file} has already been
4053 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4058 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4060 @cindex @code{fill} directive
4061 @cindex writing patterns in memory
4062 @cindex patterns, writing in memory
4063 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4064 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4065 may be zero or more. @var{Size} may be zero or more, but if it is
4066 more than 8, then it is deemed to have the value 8, compatible with
4067 other people's assemblers. The contents of each @var{repeat} bytes
4068 is taken from an 8-byte number. The highest order 4 bytes are
4069 zero. The lowest order 4 bytes are @var{value} rendered in the
4070 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4071 Each @var{size} bytes in a repetition is taken from the lowest order
4072 @var{size} bytes of this number. Again, this bizarre behavior is
4073 compatible with other people's assemblers.
4075 @var{size} and @var{value} are optional.
4076 If the second comma and @var{value} are absent, @var{value} is
4077 assumed zero. If the first comma and following tokens are absent,
4078 @var{size} is assumed to be 1.
4081 @section @code{.float @var{flonums}}
4083 @cindex floating point numbers (single)
4084 @cindex @code{float} directive
4085 This directive assembles zero or more flonums, separated by commas. It
4086 has the same effect as @code{.single}.
4088 The exact kind of floating point numbers emitted depends on how
4089 @command{@value{AS}} is configured.
4090 @xref{Machine Dependencies}.
4094 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4095 in @sc{ieee} format.
4100 @section @code{.func @var{name}[,@var{label}]}
4101 @cindex @code{func} directive
4102 @code{.func} emits debugging information to denote function @var{name}, and
4103 is ignored unless the file is assembled with debugging enabled.
4104 Only @samp{--gstabs} is currently supported.
4105 @var{label} is the entry point of the function and if omitted @var{name}
4106 prepended with the @samp{leading char} is used.
4107 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4108 All functions are currently defined to have @code{void} return type.
4109 The function must be terminated with @code{.endfunc}.
4112 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4114 @cindex @code{global} directive
4115 @cindex symbol, making visible to linker
4116 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4117 @var{symbol} in your partial program, its value is made available to
4118 other partial programs that are linked with it. Otherwise,
4119 @var{symbol} takes its attributes from a symbol of the same name
4120 from another file linked into the same program.
4122 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4123 compatibility with other assemblers.
4126 On the HPPA, @code{.global} is not always enough to make it accessible to other
4127 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4128 @xref{HPPA Directives,, HPPA Assembler Directives}.
4133 @section @code{.hidden @var{names}}
4135 @cindex @code{.hidden} directive
4137 This one of the ELF visibility directives. The other two are
4138 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4139 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4141 This directive overrides the named symbols default visibility (which is set by
4142 their binding: local, global or weak). The directive sets the visibility to
4143 @code{hidden} which means that the symbols are not visible to other components.
4144 Such symbols are always considered to be @code{protected} as well.
4148 @section @code{.hword @var{expressions}}
4150 @cindex @code{hword} directive
4151 @cindex integers, 16-bit
4152 @cindex numbers, 16-bit
4153 @cindex sixteen bit integers
4154 This expects zero or more @var{expressions}, and emits
4155 a 16 bit number for each.
4158 This directive is a synonym for @samp{.short}; depending on the target
4159 architecture, it may also be a synonym for @samp{.word}.
4163 This directive is a synonym for @samp{.short}.
4166 This directive is a synonym for both @samp{.short} and @samp{.word}.
4171 @section @code{.ident}
4173 @cindex @code{ident} directive
4174 This directive is used by some assemblers to place tags in object files.
4175 @command{@value{AS}} simply accepts the directive for source-file
4176 compatibility with such assemblers, but does not actually emit anything
4180 @section @code{.if @var{absolute expression}}
4182 @cindex conditional assembly
4183 @cindex @code{if} directive
4184 @code{.if} marks the beginning of a section of code which is only
4185 considered part of the source program being assembled if the argument
4186 (which must be an @var{absolute expression}) is non-zero. The end of
4187 the conditional section of code must be marked by @code{.endif}
4188 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4189 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4190 If you have several conditions to check, @code{.elseif} may be used to avoid
4191 nesting blocks if/else within each subsequent @code{.else} block.
4193 The following variants of @code{.if} are also supported:
4195 @cindex @code{ifdef} directive
4196 @item .ifdef @var{symbol}
4197 Assembles the following section of code if the specified @var{symbol}
4200 @cindex @code{ifc} directive
4201 @item .ifc @var{string1},@var{string2}
4202 Assembles the following section of code if the two strings are the same. The
4203 strings may be optionally quoted with single quotes. If they are not quoted,
4204 the first string stops at the first comma, and the second string stops at the
4205 end of the line. Strings which contain whitespace should be quoted. The
4206 string comparison is case sensitive.
4208 @cindex @code{ifeq} directive
4209 @item .ifeq @var{absolute expression}
4210 Assembles the following section of code if the argument is zero.
4212 @cindex @code{ifeqs} directive
4213 @item .ifeqs @var{string1},@var{string2}
4214 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4216 @cindex @code{ifge} directive
4217 @item .ifge @var{absolute expression}
4218 Assembles the following section of code if the argument is greater than or
4221 @cindex @code{ifgt} directive
4222 @item .ifgt @var{absolute expression}
4223 Assembles the following section of code if the argument is greater than zero.
4225 @cindex @code{ifle} directive
4226 @item .ifle @var{absolute expression}
4227 Assembles the following section of code if the argument is less than or equal
4230 @cindex @code{iflt} directive
4231 @item .iflt @var{absolute expression}
4232 Assembles the following section of code if the argument is less than zero.
4234 @cindex @code{ifnc} directive
4235 @item .ifnc @var{string1},@var{string2}.
4236 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4237 following section of code if the two strings are not the same.
4239 @cindex @code{ifndef} directive
4240 @cindex @code{ifnotdef} directive
4241 @item .ifndef @var{symbol}
4242 @itemx .ifnotdef @var{symbol}
4243 Assembles the following section of code if the specified @var{symbol}
4244 has not been defined. Both spelling variants are equivalent.
4246 @cindex @code{ifne} directive
4247 @item .ifne @var{absolute expression}
4248 Assembles the following section of code if the argument is not equal to zero
4249 (in other words, this is equivalent to @code{.if}).
4251 @cindex @code{ifnes} directive
4252 @item .ifnes @var{string1},@var{string2}
4253 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4254 following section of code if the two strings are not the same.
4258 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4260 @cindex @code{incbin} directive
4261 @cindex binary files, including
4262 The @code{incbin} directive includes @var{file} verbatim at the current
4263 location. You can control the search paths used with the @samp{-I} command-line
4264 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4267 The @var{skip} argument skips a number of bytes from the start of the
4268 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4269 read. Note that the data is not aligned in any way, so it is the user's
4270 responsibility to make sure that proper alignment is provided both before and
4271 after the @code{incbin} directive.
4274 @section @code{.include "@var{file}"}
4276 @cindex @code{include} directive
4277 @cindex supporting files, including
4278 @cindex files, including
4279 This directive provides a way to include supporting files at specified
4280 points in your source program. The code from @var{file} is assembled as
4281 if it followed the point of the @code{.include}; when the end of the
4282 included file is reached, assembly of the original file continues. You
4283 can control the search paths used with the @samp{-I} command-line option
4284 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4288 @section @code{.int @var{expressions}}
4290 @cindex @code{int} directive
4291 @cindex integers, 32-bit
4292 Expect zero or more @var{expressions}, of any section, separated by commas.
4293 For each expression, emit a number that, at run time, is the value of that
4294 expression. The byte order and bit size of the number depends on what kind
4295 of target the assembly is for.
4299 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4300 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4307 @section @code{.internal @var{names}}
4309 @cindex @code{.internal} directive
4311 This one of the ELF visibility directives. The other two are
4312 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4313 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4315 This directive overrides the named symbols default visibility (which is set by
4316 their binding: local, global or weak). The directive sets the visibility to
4317 @code{internal} which means that the symbols are considered to be @code{hidden}
4318 (ie not visible to other components), and that some extra, processor specific
4319 processing must also be performed upon the symbols as well.
4323 @section @code{.irp @var{symbol},@var{values}}@dots{}
4325 @cindex @code{irp} directive
4326 Evaluate a sequence of statements assigning different values to @var{symbol}.
4327 The sequence of statements starts at the @code{.irp} directive, and is
4328 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4329 set to @var{value}, and the sequence of statements is assembled. If no
4330 @var{value} is listed, the sequence of statements is assembled once, with
4331 @var{symbol} set to the null string. To refer to @var{symbol} within the
4332 sequence of statements, use @var{\symbol}.
4334 For example, assembling
4342 is equivalent to assembling
4351 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4353 @cindex @code{irpc} directive
4354 Evaluate a sequence of statements assigning different values to @var{symbol}.
4355 The sequence of statements starts at the @code{.irpc} directive, and is
4356 terminated by an @code{.endr} directive. For each character in @var{value},
4357 @var{symbol} is set to the character, and the sequence of statements is
4358 assembled. If no @var{value} is listed, the sequence of statements is
4359 assembled once, with @var{symbol} set to the null string. To refer to
4360 @var{symbol} within the sequence of statements, use @var{\symbol}.
4362 For example, assembling
4370 is equivalent to assembling
4379 @section @code{.lcomm @var{symbol} , @var{length}}
4381 @cindex @code{lcomm} directive
4382 @cindex local common symbols
4383 @cindex symbols, local common
4384 Reserve @var{length} (an absolute expression) bytes for a local common
4385 denoted by @var{symbol}. The section and value of @var{symbol} are
4386 those of the new local common. The addresses are allocated in the bss
4387 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4388 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4389 not visible to @code{@value{LD}}.
4392 Some targets permit a third argument to be used with @code{.lcomm}. This
4393 argument specifies the desired alignment of the symbol in the bss section.
4397 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4398 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4402 @section @code{.lflags}
4404 @cindex @code{lflags} directive (ignored)
4405 @command{@value{AS}} accepts this directive, for compatibility with other
4406 assemblers, but ignores it.
4408 @ifclear no-line-dir
4410 @section @code{.line @var{line-number}}
4412 @cindex @code{line} directive
4416 @section @code{.ln @var{line-number}}
4418 @cindex @code{ln} directive
4420 @cindex logical line number
4422 Change the logical line number. @var{line-number} must be an absolute
4423 expression. The next line has that logical line number. Therefore any other
4424 statements on the current line (after a statement separator character) are
4425 reported as on logical line number @var{line-number} @minus{} 1. One day
4426 @command{@value{AS}} will no longer support this directive: it is recognized only
4427 for compatibility with existing assembler programs.
4431 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4432 not available; use the synonym @code{.ln} in that context.
4437 @ifclear no-line-dir
4438 Even though this is a directive associated with the @code{a.out} or
4439 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4440 when producing COFF output, and treats @samp{.line} as though it
4441 were the COFF @samp{.ln} @emph{if} it is found outside a
4442 @code{.def}/@code{.endef} pair.
4444 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4445 used by compilers to generate auxiliary symbol information for
4450 @section @code{.linkonce [@var{type}]}
4452 @cindex @code{linkonce} directive
4453 @cindex common sections
4454 Mark the current section so that the linker only includes a single copy of it.
4455 This may be used to include the same section in several different object files,
4456 but ensure that the linker will only include it once in the final output file.
4457 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4458 Duplicate sections are detected based on the section name, so it should be
4461 This directive is only supported by a few object file formats; as of this
4462 writing, the only object file format which supports it is the Portable
4463 Executable format used on Windows NT.
4465 The @var{type} argument is optional. If specified, it must be one of the
4466 following strings. For example:
4470 Not all types may be supported on all object file formats.
4474 Silently discard duplicate sections. This is the default.
4477 Warn if there are duplicate sections, but still keep only one copy.
4480 Warn if any of the duplicates have different sizes.
4483 Warn if any of the duplicates do not have exactly the same contents.
4487 @section @code{.ln @var{line-number}}
4489 @cindex @code{ln} directive
4490 @ifclear no-line-dir
4491 @samp{.ln} is a synonym for @samp{.line}.
4494 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4495 must be an absolute expression. The next line has that logical
4496 line number, so any other statements on the current line (after a
4497 statement separator character @code{;}) are reported as on logical
4498 line number @var{line-number} @minus{} 1.
4501 This directive is accepted, but ignored, when @command{@value{AS}} is
4502 configured for @code{b.out}; its effect is only associated with COFF
4508 @section @code{.mri @var{val}}
4510 @cindex @code{mri} directive
4511 @cindex MRI mode, temporarily
4512 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4513 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4514 affects code assembled until the next @code{.mri} directive, or until the end
4515 of the file. @xref{M, MRI mode, MRI mode}.
4518 @section @code{.list}
4520 @cindex @code{list} directive
4521 @cindex listing control, turning on
4522 Control (in conjunction with the @code{.nolist} directive) whether or
4523 not assembly listings are generated. These two directives maintain an
4524 internal counter (which is zero initially). @code{.list} increments the
4525 counter, and @code{.nolist} decrements it. Assembly listings are
4526 generated whenever the counter is greater than zero.
4528 By default, listings are disabled. When you enable them (with the
4529 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4530 the initial value of the listing counter is one.
4533 @section @code{.long @var{expressions}}
4535 @cindex @code{long} directive
4536 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4539 @c no one seems to know what this is for or whether this description is
4540 @c what it really ought to do
4542 @section @code{.lsym @var{symbol}, @var{expression}}
4544 @cindex @code{lsym} directive
4545 @cindex symbol, not referenced in assembly
4546 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4547 the hash table, ensuring it cannot be referenced by name during the
4548 rest of the assembly. This sets the attributes of the symbol to be
4549 the same as the expression value:
4551 @var{other} = @var{descriptor} = 0
4552 @var{type} = @r{(section of @var{expression})}
4553 @var{value} = @var{expression}
4556 The new symbol is not flagged as external.
4560 @section @code{.macro}
4563 The commands @code{.macro} and @code{.endm} allow you to define macros that
4564 generate assembly output. For example, this definition specifies a macro
4565 @code{sum} that puts a sequence of numbers into memory:
4568 .macro sum from=0, to=5
4577 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4589 @item .macro @var{macname}
4590 @itemx .macro @var{macname} @var{macargs} @dots{}
4591 @cindex @code{macro} directive
4592 Begin the definition of a macro called @var{macname}. If your macro
4593 definition requires arguments, specify their names after the macro name,
4594 separated by commas or spaces. You can supply a default value for any
4595 macro argument by following the name with @samp{=@var{deflt}}. For
4596 example, these are all valid @code{.macro} statements:
4600 Begin the definition of a macro called @code{comm}, which takes no
4603 @item .macro plus1 p, p1
4604 @itemx .macro plus1 p p1
4605 Either statement begins the definition of a macro called @code{plus1},
4606 which takes two arguments; within the macro definition, write
4607 @samp{\p} or @samp{\p1} to evaluate the arguments.
4609 @item .macro reserve_str p1=0 p2
4610 Begin the definition of a macro called @code{reserve_str}, with two
4611 arguments. The first argument has a default value, but not the second.
4612 After the definition is complete, you can call the macro either as
4613 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4614 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4615 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4616 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4619 When you call a macro, you can specify the argument values either by
4620 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4621 @samp{sum to=17, from=9}.
4624 @cindex @code{endm} directive
4625 Mark the end of a macro definition.
4628 @cindex @code{exitm} directive
4629 Exit early from the current macro definition.
4631 @cindex number of macros executed
4632 @cindex macros, count executed
4634 @command{@value{AS}} maintains a counter of how many macros it has
4635 executed in this pseudo-variable; you can copy that number to your
4636 output with @samp{\@@}, but @emph{only within a macro definition}.
4639 @item LOCAL @var{name} [ , @dots{} ]
4640 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4641 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4642 Alternate macro syntax}.
4644 Generate a string replacement for each of the @var{name} arguments, and
4645 replace any instances of @var{name} in each macro expansion. The
4646 replacement string is unique in the assembly, and different for each
4647 separate macro expansion. @code{LOCAL} allows you to write macros that
4648 define symbols, without fear of conflict between separate macro expansions.
4653 @section @code{.nolist}
4655 @cindex @code{nolist} directive
4656 @cindex listing control, turning off
4657 Control (in conjunction with the @code{.list} directive) whether or
4658 not assembly listings are generated. These two directives maintain an
4659 internal counter (which is zero initially). @code{.list} increments the
4660 counter, and @code{.nolist} decrements it. Assembly listings are
4661 generated whenever the counter is greater than zero.
4664 @section @code{.octa @var{bignums}}
4666 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4667 @cindex @code{octa} directive
4668 @cindex integer, 16-byte
4669 @cindex sixteen byte integer
4670 This directive expects zero or more bignums, separated by commas. For each
4671 bignum, it emits a 16-byte integer.
4673 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4674 hence @emph{octa}-word for 16 bytes.
4677 @section @code{.org @var{new-lc} , @var{fill}}
4679 @cindex @code{org} directive
4680 @cindex location counter, advancing
4681 @cindex advancing location counter
4682 @cindex current address, advancing
4683 Advance the location counter of the current section to
4684 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4685 expression with the same section as the current subsection. That is,
4686 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4687 wrong section, the @code{.org} directive is ignored. To be compatible
4688 with former assemblers, if the section of @var{new-lc} is absolute,
4689 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4690 is the same as the current subsection.
4692 @code{.org} may only increase the location counter, or leave it
4693 unchanged; you cannot use @code{.org} to move the location counter
4696 @c double negative used below "not undefined" because this is a specific
4697 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4698 @c section. doc@cygnus.com 18feb91
4699 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4700 may not be undefined. If you really detest this restriction we eagerly await
4701 a chance to share your improved assembler.
4703 Beware that the origin is relative to the start of the section, not
4704 to the start of the subsection. This is compatible with other
4705 people's assemblers.
4707 When the location counter (of the current subsection) is advanced, the
4708 intervening bytes are filled with @var{fill} which should be an
4709 absolute expression. If the comma and @var{fill} are omitted,
4710 @var{fill} defaults to zero.
4713 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4715 @cindex padding the location counter given a power of two
4716 @cindex @code{p2align} directive
4717 Pad the location counter (in the current subsection) to a particular
4718 storage boundary. The first expression (which must be absolute) is the
4719 number of low-order zero bits the location counter must have after
4720 advancement. For example @samp{.p2align 3} advances the location
4721 counter until it a multiple of 8. If the location counter is already a
4722 multiple of 8, no change is needed.
4724 The second expression (also absolute) gives the fill value to be stored in the
4725 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4726 padding bytes are normally zero. However, on some systems, if the section is
4727 marked as containing code and the fill value is omitted, the space is filled
4728 with no-op instructions.
4730 The third expression is also absolute, and is also optional. If it is present,
4731 it is the maximum number of bytes that should be skipped by this alignment
4732 directive. If doing the alignment would require skipping more bytes than the
4733 specified maximum, then the alignment is not done at all. You can omit the
4734 fill value (the second argument) entirely by simply using two commas after the
4735 required alignment; this can be useful if you want the alignment to be filled
4736 with no-op instructions when appropriate.
4738 @cindex @code{p2alignw} directive
4739 @cindex @code{p2alignl} directive
4740 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4741 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4742 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4743 fill pattern as a four byte longword value. For example, @code{.p2alignw
4744 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4745 filled in with the value 0x368d (the exact placement of the bytes depends upon
4746 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4751 @section @code{.previous}
4753 @cindex @code{.previous} directive
4754 @cindex Section Stack
4755 This is one of the ELF section stack manipulation directives. The others are
4756 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4757 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4758 (@pxref{PopSection}).
4760 This directive swaps the current section (and subsection) with most recently
4761 referenced section (and subsection) prior to this one. Multiple
4762 @code{.previous} directives in a row will flip between two sections (and their
4765 In terms of the section stack, this directive swaps the current section with
4766 the top section on the section stack.
4771 @section @code{.popsection}
4773 @cindex @code{.popsection} directive
4774 @cindex Section Stack
4775 This is one of the ELF section stack manipulation directives. The others are
4776 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4777 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4780 This directive replaces the current section (and subsection) with the top
4781 section (and subsection) on the section stack. This section is popped off the
4786 @section @code{.print @var{string}}
4788 @cindex @code{print} directive
4789 @command{@value{AS}} will print @var{string} on the standard output during
4790 assembly. You must put @var{string} in double quotes.
4794 @section @code{.protected @var{names}}
4796 @cindex @code{.protected} directive
4798 This one of the ELF visibility directives. The other two are
4799 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4801 This directive overrides the named symbols default visibility (which is set by
4802 their binding: local, global or weak). The directive sets the visibility to
4803 @code{protected} which means that any references to the symbols from within the
4804 components that defines them must be resolved to the definition in that
4805 component, even if a definition in another component would normally preempt
4810 @section @code{.psize @var{lines} , @var{columns}}
4812 @cindex @code{psize} directive
4813 @cindex listing control: paper size
4814 @cindex paper size, for listings
4815 Use this directive to declare the number of lines---and, optionally, the
4816 number of columns---to use for each page, when generating listings.
4818 If you do not use @code{.psize}, listings use a default line-count
4819 of 60. You may omit the comma and @var{columns} specification; the
4820 default width is 200 columns.
4822 @command{@value{AS}} generates formfeeds whenever the specified number of
4823 lines is exceeded (or whenever you explicitly request one, using
4826 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4827 those explicitly specified with @code{.eject}.
4830 @section @code{.purgem @var{name}}
4832 @cindex @code{purgem} directive
4833 Undefine the macro @var{name}, so that later uses of the string will not be
4834 expanded. @xref{Macro}.
4838 @section @code{.pushsection @var{name} , @var{subsection}}
4840 @cindex @code{.pushsection} directive
4841 @cindex Section Stack
4842 This is one of the ELF section stack manipulation directives. The others are
4843 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4844 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4847 This directive is a synonym for @code{.section}. It pushes the current section
4848 (and subsection) onto the top of the section stack, and then replaces the
4849 current section and subsection with @code{name} and @code{subsection}.
4853 @section @code{.quad @var{bignums}}
4855 @cindex @code{quad} directive
4856 @code{.quad} expects zero or more bignums, separated by commas. For
4857 each bignum, it emits
4859 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4860 warning message; and just takes the lowest order 8 bytes of the bignum.
4861 @cindex eight-byte integer
4862 @cindex integer, 8-byte
4864 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4865 hence @emph{quad}-word for 8 bytes.
4868 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4869 warning message; and just takes the lowest order 16 bytes of the bignum.
4870 @cindex sixteen-byte integer
4871 @cindex integer, 16-byte
4875 @section @code{.rept @var{count}}
4877 @cindex @code{rept} directive
4878 Repeat the sequence of lines between the @code{.rept} directive and the next
4879 @code{.endr} directive @var{count} times.
4881 For example, assembling
4889 is equivalent to assembling
4898 @section @code{.sbttl "@var{subheading}"}
4900 @cindex @code{sbttl} directive
4901 @cindex subtitles for listings
4902 @cindex listing control: subtitle
4903 Use @var{subheading} as the title (third line, immediately after the
4904 title line) when generating assembly listings.
4906 This directive affects subsequent pages, as well as the current page if
4907 it appears within ten lines of the top of a page.
4911 @section @code{.scl @var{class}}
4913 @cindex @code{scl} directive
4914 @cindex symbol storage class (COFF)
4915 @cindex COFF symbol storage class
4916 Set the storage-class value for a symbol. This directive may only be
4917 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4918 whether a symbol is static or external, or it may record further
4919 symbolic debugging information.
4922 The @samp{.scl} directive is primarily associated with COFF output; when
4923 configured to generate @code{b.out} output format, @command{@value{AS}}
4924 accepts this directive but ignores it.
4929 @section @code{.section @var{name}} (COFF version)
4931 @cindex @code{section} directive
4932 @cindex named section
4933 Use the @code{.section} directive to assemble the following code into a section
4936 This directive is only supported for targets that actually support arbitrarily
4937 named sections; on @code{a.out} targets, for example, it is not accepted, even
4938 with a standard @code{a.out} section name.
4940 For COFF targets, the @code{.section} directive is used in one of the following
4944 .section @var{name}[, "@var{flags}"]
4945 .section @var{name}[, @var{subsegment}]
4948 If the optional argument is quoted, it is taken as flags to use for the
4949 section. Each flag is a single character. The following flags are recognized:
4952 bss section (uninitialized data)
4954 section is not loaded
4964 shared section (meaningful for PE targets)
4967 If no flags are specified, the default flags depend upon the section name. If
4968 the section name is not recognized, the default will be for the section to be
4969 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4970 from the section, rather than adding them, so if they are used on their own it
4971 will be as if no flags had been specified at all.
4973 If the optional argument to the @code{.section} directive is not quoted, it is
4974 taken as a subsegment number (@pxref{Sub-Sections}).
4977 @section @code{.section @var{name}} (ELF version)
4979 @cindex @code{section} directive
4980 @cindex named section
4982 @cindex Section Stack
4983 This is one of the ELF section stack manipulation directives. The others are
4984 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4985 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4986 @code{.previous} (@pxref{Previous}).
4989 For ELF targets, the @code{.section} directive is used like this:
4992 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
4995 The optional @var{flags} argument is a quoted string which may contain any
4996 combination of the following characters:
4999 section is allocatable
5003 section is executable
5005 section is mergeable
5007 section contains zero terminated strings
5010 The optional @var{type} argument may contain one of the following constants:
5013 section contains data
5015 section does not contain data (i.e., section only occupies space)
5018 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5019 as well as @var{entsize} argument. Sections with @code{M} flag but not
5020 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5021 long. Sections with both @code{M} and @code{S} must contain zero terminated
5022 strings where each character is @var{entsize} bytes long. The linker may remove
5023 duplicates within sections with the same name, same entity size and same flags.
5025 If no flags are specified, the default flags depend upon the section name. If
5026 the section name is not recognized, the default will be for the section to have
5027 none of the above flags: it will not be allocated in memory, nor writable, nor
5028 executable. The section will contain data.
5030 For ELF targets, the assembler supports another type of @code{.section}
5031 directive for compatibility with the Solaris assembler:
5034 .section "@var{name}"[, @var{flags}...]
5037 Note that the section name is quoted. There may be a sequence of comma
5041 section is allocatable
5045 section is executable
5048 This directive replaces the current section and subsection. The replaced
5049 section and subsection are pushed onto the section stack. See the contents of
5050 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5051 how this directive and the other section stack directives work.
5054 @section @code{.set @var{symbol}, @var{expression}}
5056 @cindex @code{set} directive
5057 @cindex symbol value, setting
5058 Set the value of @var{symbol} to @var{expression}. This
5059 changes @var{symbol}'s value and type to conform to
5060 @var{expression}. If @var{symbol} was flagged as external, it remains
5061 flagged (@pxref{Symbol Attributes}).
5063 You may @code{.set} a symbol many times in the same assembly.
5065 If you @code{.set} a global symbol, the value stored in the object
5066 file is the last value stored into it.
5069 The syntax for @code{set} on the HPPA is
5070 @samp{@var{symbol} .set @var{expression}}.
5074 @section @code{.short @var{expressions}}
5076 @cindex @code{short} directive
5078 @code{.short} is normally the same as @samp{.word}.
5079 @xref{Word,,@code{.word}}.
5081 In some configurations, however, @code{.short} and @code{.word} generate
5082 numbers of different lengths; @pxref{Machine Dependencies}.
5086 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5089 This expects zero or more @var{expressions}, and emits
5090 a 16 bit number for each.
5095 @section @code{.single @var{flonums}}
5097 @cindex @code{single} directive
5098 @cindex floating point numbers (single)
5099 This directive assembles zero or more flonums, separated by commas. It
5100 has the same effect as @code{.float}.
5102 The exact kind of floating point numbers emitted depends on how
5103 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5107 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5108 numbers in @sc{ieee} format.
5113 @section @code{.size} (COFF version)
5115 @cindex @code{size} directive
5116 This directive is generated by compilers to include auxiliary debugging
5117 information in the symbol table. It is only permitted inside
5118 @code{.def}/@code{.endef} pairs.
5121 @samp{.size} is only meaningful when generating COFF format output; when
5122 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5126 @section @code{.size @var{name} , @var{expression}} (ELF version)
5127 @cindex @code{size} directive
5129 This directive is used to set the size associated with a symbol @var{name}.
5130 The size in bytes is computed from @var{expression} which can make use of label
5131 arithmetic. This directive is typically used to set the size of function
5135 @section @code{.sleb128 @var{expressions}}
5137 @cindex @code{sleb128} directive
5138 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5139 compact, variable length representation of numbers used by the DWARF
5140 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5142 @ifclear no-space-dir
5144 @section @code{.skip @var{size} , @var{fill}}
5146 @cindex @code{skip} directive
5147 @cindex filling memory
5148 This directive emits @var{size} bytes, each of value @var{fill}. Both
5149 @var{size} and @var{fill} are absolute expressions. If the comma and
5150 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5154 @section @code{.space @var{size} , @var{fill}}
5156 @cindex @code{space} directive
5157 @cindex filling memory
5158 This directive emits @var{size} bytes, each of value @var{fill}. Both
5159 @var{size} and @var{fill} are absolute expressions. If the comma
5160 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5165 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5166 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5167 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5168 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5177 @section @code{.space}
5178 @cindex @code{space} directive
5180 On the AMD 29K, this directive is ignored; it is accepted for
5181 compatibility with other AMD 29K assemblers.
5184 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5185 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5191 @section @code{.stabd, .stabn, .stabs}
5193 @cindex symbolic debuggers, information for
5194 @cindex @code{stab@var{x}} directives
5195 There are three directives that begin @samp{.stab}.
5196 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5197 The symbols are not entered in the @command{@value{AS}} hash table: they
5198 cannot be referenced elsewhere in the source file.
5199 Up to five fields are required:
5203 This is the symbol's name. It may contain any character except
5204 @samp{\000}, so is more general than ordinary symbol names. Some
5205 debuggers used to code arbitrarily complex structures into symbol names
5209 An absolute expression. The symbol's type is set to the low 8 bits of
5210 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5211 and debuggers choke on silly bit patterns.
5214 An absolute expression. The symbol's ``other'' attribute is set to the
5215 low 8 bits of this expression.
5218 An absolute expression. The symbol's descriptor is set to the low 16
5219 bits of this expression.
5222 An absolute expression which becomes the symbol's value.
5225 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5226 or @code{.stabs} statement, the symbol has probably already been created;
5227 you get a half-formed symbol in your object file. This is
5228 compatible with earlier assemblers!
5231 @cindex @code{stabd} directive
5232 @item .stabd @var{type} , @var{other} , @var{desc}
5234 The ``name'' of the symbol generated is not even an empty string.
5235 It is a null pointer, for compatibility. Older assemblers used a
5236 null pointer so they didn't waste space in object files with empty
5239 The symbol's value is set to the location counter,
5240 relocatably. When your program is linked, the value of this symbol
5241 is the address of the location counter when the @code{.stabd} was
5244 @cindex @code{stabn} directive
5245 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5246 The name of the symbol is set to the empty string @code{""}.
5248 @cindex @code{stabs} directive
5249 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5250 All five fields are specified.
5256 @section @code{.string} "@var{str}"
5258 @cindex string, copying to object file
5259 @cindex @code{string} directive
5261 Copy the characters in @var{str} to the object file. You may specify more than
5262 one string to copy, separated by commas. Unless otherwise specified for a
5263 particular machine, the assembler marks the end of each string with a 0 byte.
5264 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5267 @section @code{.struct @var{expression}}
5269 @cindex @code{struct} directive
5270 Switch to the absolute section, and set the section offset to @var{expression},
5271 which must be an absolute expression. You might use this as follows:
5280 This would define the symbol @code{field1} to have the value 0, the symbol
5281 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5282 value 8. Assembly would be left in the absolute section, and you would need to
5283 use a @code{.section} directive of some sort to change to some other section
5284 before further assembly.
5288 @section @code{.subsection @var{name}}
5290 @cindex @code{.subsection} directive
5291 @cindex Section Stack
5292 This is one of the ELF section stack manipulation directives. The others are
5293 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5294 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5297 This directive replaces the current subsection with @code{name}. The current
5298 section is not changed. The replaced subsection is put onto the section stack
5299 in place of the then current top of stack subsection.
5304 @section @code{.symver}
5305 @cindex @code{symver} directive
5306 @cindex symbol versioning
5307 @cindex versions of symbols
5308 Use the @code{.symver} directive to bind symbols to specific version nodes
5309 within a source file. This is only supported on ELF platforms, and is
5310 typically used when assembling files to be linked into a shared library.
5311 There are cases where it may make sense to use this in objects to be bound
5312 into an application itself so as to override a versioned symbol from a
5315 For ELF targets, the @code{.symver} directive can be used like this:
5317 .symver @var{name}, @var{name2@@nodename}
5319 If the symbol @var{name} is defined within the file
5320 being assembled, the @code{.symver} directive effectively creates a symbol
5321 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5322 just don't try and create a regular alias is that the @var{@@} character isn't
5323 permitted in symbol names. The @var{name2} part of the name is the actual name
5324 of the symbol by which it will be externally referenced. The name @var{name}
5325 itself is merely a name of convenience that is used so that it is possible to
5326 have definitions for multiple versions of a function within a single source
5327 file, and so that the compiler can unambiguously know which version of a
5328 function is being mentioned. The @var{nodename} portion of the alias should be
5329 the name of a node specified in the version script supplied to the linker when
5330 building a shared library. If you are attempting to override a versioned
5331 symbol from a shared library, then @var{nodename} should correspond to the
5332 nodename of the symbol you are trying to override.
5334 If the symbol @var{name} is not defined within the file being assembled, all
5335 references to @var{name} will be changed to @var{name2@@nodename}. If no
5336 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5339 Another usage of the @code{.symver} directive is:
5341 .symver @var{name}, @var{name2@@@@nodename}
5343 In this case, the symbol @var{name} must exist and be defined within
5344 the file being assembled. It is similar to @var{name2@@nodename}. The
5345 difference is @var{name2@@@@nodename} will also be used to resolve
5346 references to @var{name2} by the linker.
5348 The third usage of the @code{.symver} directive is:
5350 .symver @var{name}, @var{name2@@@@@@nodename}
5352 When @var{name} is not defined within the
5353 file being assembled, it is treated as @var{name2@@nodename}. When
5354 @var{name} is defined within the file being assembled, the symbol
5355 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5360 @section @code{.tag @var{structname}}
5362 @cindex COFF structure debugging
5363 @cindex structure debugging, COFF
5364 @cindex @code{tag} directive
5365 This directive is generated by compilers to include auxiliary debugging
5366 information in the symbol table. It is only permitted inside
5367 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5368 definitions in the symbol table with instances of those structures.
5371 @samp{.tag} is only used when generating COFF format output; when
5372 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5378 @section @code{.text @var{subsection}}
5380 @cindex @code{text} directive
5381 Tells @command{@value{AS}} to assemble the following statements onto the end of
5382 the text subsection numbered @var{subsection}, which is an absolute
5383 expression. If @var{subsection} is omitted, subsection number zero
5387 @section @code{.title "@var{heading}"}
5389 @cindex @code{title} directive
5390 @cindex listing control: title line
5391 Use @var{heading} as the title (second line, immediately after the
5392 source file name and pagenumber) when generating assembly listings.
5394 This directive affects subsequent pages, as well as the current page if
5395 it appears within ten lines of the top of a page.
5398 @section @code{.type @var{int}} (COFF version)
5400 @cindex COFF symbol type
5401 @cindex symbol type, COFF
5402 @cindex @code{type} directive
5403 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5404 records the integer @var{int} as the type attribute of a symbol table entry.
5407 @samp{.type} is associated only with COFF format output; when
5408 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5409 directive but ignores it.
5412 @section @code{.type @var{name} , @var{type description}} (ELF version)
5414 @cindex ELF symbol type
5415 @cindex symbol type, ELF
5416 @cindex @code{type} directive
5417 This directive is used to set the type of symbol @var{name} to be either a
5418 function symbol or an object symbol. There are five different syntaxes
5419 supported for the @var{type description} field, in order to provide
5420 compatibility with various other assemblers. The syntaxes supported are:
5423 .type <name>,#function
5424 .type <name>,#object
5426 .type <name>,@@function
5427 .type <name>,@@object
5429 .type <name>,%function
5430 .type <name>,%object
5432 .type <name>,"function"
5433 .type <name>,"object"
5435 .type <name> STT_FUNCTION
5436 .type <name> STT_OBJECT
5440 @section @code{.uleb128 @var{expressions}}
5442 @cindex @code{uleb128} directive
5443 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5444 compact, variable length representation of numbers used by the DWARF
5445 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5449 @section @code{.val @var{addr}}
5451 @cindex @code{val} directive
5452 @cindex COFF value attribute
5453 @cindex value attribute, COFF
5454 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5455 records the address @var{addr} as the value attribute of a symbol table
5459 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5460 configured for @code{b.out}, it accepts this directive but ignores it.
5466 @section @code{.version "@var{string}"}
5468 @cindex @code{.version}
5469 This directive creates a @code{.note} section and places into it an ELF
5470 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5475 @section @code{.vtable_entry @var{table}, @var{offset}}
5477 @cindex @code{.vtable_entry}
5478 This directive finds or creates a symbol @code{table} and creates a
5479 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5482 @section @code{.vtable_inherit @var{child}, @var{parent}}
5484 @cindex @code{.vtable_inherit}
5485 This directive finds the symbol @code{child} and finds or creates the symbol
5486 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5487 parent whose addend is the value of the child symbol. As a special case the
5488 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5493 @section @code{.weak @var{names}}
5495 @cindex @code{.weak}
5496 This directive sets the weak attribute on the comma separated list of symbol
5497 @code{names}. If the symbols do not already exist, they will be created.
5501 @section @code{.word @var{expressions}}
5503 @cindex @code{word} directive
5504 This directive expects zero or more @var{expressions}, of any section,
5505 separated by commas.
5508 For each expression, @command{@value{AS}} emits a 32-bit number.
5511 For each expression, @command{@value{AS}} emits a 16-bit number.
5516 The size of the number emitted, and its byte order,
5517 depend on what target computer the assembly is for.
5520 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5521 @c happen---32-bit addressability, period; no long/short jumps.
5522 @ifset DIFF-TBL-KLUGE
5523 @cindex difference tables altered
5524 @cindex altered difference tables
5526 @emph{Warning: Special Treatment to support Compilers}
5530 Machines with a 32-bit address space, but that do less than 32-bit
5531 addressing, require the following special treatment. If the machine of
5532 interest to you does 32-bit addressing (or doesn't require it;
5533 @pxref{Machine Dependencies}), you can ignore this issue.
5536 In order to assemble compiler output into something that works,
5537 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5538 Directives of the form @samp{.word sym1-sym2} are often emitted by
5539 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5540 directive of the form @samp{.word sym1-sym2}, and the difference between
5541 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5542 creates a @dfn{secondary jump table}, immediately before the next label.
5543 This secondary jump table is preceded by a short-jump to the
5544 first byte after the secondary table. This short-jump prevents the flow
5545 of control from accidentally falling into the new table. Inside the
5546 table is a long-jump to @code{sym2}. The original @samp{.word}
5547 contains @code{sym1} minus the address of the long-jump to
5550 If there were several occurrences of @samp{.word sym1-sym2} before the
5551 secondary jump table, all of them are adjusted. If there was a
5552 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5553 long-jump to @code{sym4} is included in the secondary jump table,
5554 and the @code{.word} directives are adjusted to contain @code{sym3}
5555 minus the address of the long-jump to @code{sym4}; and so on, for as many
5556 entries in the original jump table as necessary.
5559 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5560 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5561 assembly language programmers.
5564 @c end DIFF-TBL-KLUGE
5567 @section Deprecated Directives
5569 @cindex deprecated directives
5570 @cindex obsolescent directives
5571 One day these directives won't work.
5572 They are included for compatibility with older assemblers.
5579 @node Machine Dependencies
5580 @chapter Machine Dependent Features
5582 @cindex machine dependencies
5583 The machine instruction sets are (almost by definition) different on
5584 each machine where @command{@value{AS}} runs. Floating point representations
5585 vary as well, and @command{@value{AS}} often supports a few additional
5586 directives or command-line options for compatibility with other
5587 assemblers on a particular platform. Finally, some versions of
5588 @command{@value{AS}} support special pseudo-instructions for branch
5591 This chapter discusses most of these differences, though it does not
5592 include details on any machine's instruction set. For details on that
5593 subject, see the hardware manufacturer's manual.
5597 * AMD29K-Dependent:: AMD 29K Dependent Features
5600 * Alpha-Dependent:: Alpha Dependent Features
5603 * ARC-Dependent:: ARC Dependent Features
5606 * ARM-Dependent:: ARM Dependent Features
5609 * CRIS-Dependent:: CRIS Dependent Features
5612 * D10V-Dependent:: D10V Dependent Features
5615 * D30V-Dependent:: D30V Dependent Features
5618 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5621 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5624 * HPPA-Dependent:: HPPA Dependent Features
5627 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5630 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5633 * i860-Dependent:: Intel 80860 Dependent Features
5636 * i960-Dependent:: Intel 80960 Dependent Features
5639 * M32R-Dependent:: M32R Dependent Features
5642 * M68K-Dependent:: M680x0 Dependent Features
5645 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5648 * M88K-Dependent:: M880x0 Dependent Features
5651 * MIPS-Dependent:: MIPS Dependent Features
5654 * MMIX-Dependent:: MMIX Dependent Features
5657 * SH-Dependent:: Hitachi SH Dependent Features
5658 * SH64-Dependent:: Hitachi SH64 Dependent Features
5661 * PDP-11-Dependent:: PDP-11 Dependent Features
5664 * PJ-Dependent:: picoJava Dependent Features
5667 * PPC-Dependent:: PowerPC Dependent Features
5670 * Sparc-Dependent:: SPARC Dependent Features
5673 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5676 * V850-Dependent:: V850 Dependent Features
5679 * Z8000-Dependent:: Z8000 Dependent Features
5682 * Vax-Dependent:: VAX Dependent Features
5689 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5690 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5691 @c peculiarity: to preserve cross-references, there must be a node called
5692 @c "Machine Dependencies". Hence the conditional nodenames in each
5693 @c major node below. Node defaulting in makeinfo requires adjacency of
5694 @c node and sectioning commands; hence the repetition of @chapter BLAH
5695 @c in both conditional blocks.
5698 @include c-a29k.texi
5702 @include c-alpha.texi
5714 @include c-cris.texi
5719 @node Machine Dependencies
5720 @chapter Machine Dependent Features
5722 The machine instruction sets are different on each Hitachi chip family,
5723 and there are also some syntax differences among the families. This
5724 chapter describes the specific @command{@value{AS}} features for each
5728 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5729 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5730 * SH-Dependent:: Hitachi SH Dependent Features
5737 @include c-d10v.texi
5741 @include c-d30v.texi
5745 @include c-h8300.texi
5749 @include c-h8500.texi
5753 @include c-hppa.texi
5757 @include c-i370.texi
5761 @include c-i386.texi
5765 @include c-i860.texi
5769 @include c-i960.texi
5773 @include c-m32r.texi
5777 @include c-m68k.texi
5781 @include c-m68hc11.texi
5785 @include c-m88k.texi
5789 @include c-mips.texi
5793 @include c-mmix.texi
5797 @include c-ns32k.texi
5801 @include c-pdp11.texi
5814 @include c-sh64.texi
5818 @include c-sparc.texi
5822 @include c-tic54x.texi
5834 @include c-v850.texi
5838 @c reverse effect of @down at top of generic Machine-Dep chapter
5842 @node Reporting Bugs
5843 @chapter Reporting Bugs
5844 @cindex bugs in assembler
5845 @cindex reporting bugs in assembler
5847 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5849 Reporting a bug may help you by bringing a solution to your problem, or it may
5850 not. But in any case the principal function of a bug report is to help the
5851 entire community by making the next version of @command{@value{AS}} work better.
5852 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5854 In order for a bug report to serve its purpose, you must include the
5855 information that enables us to fix the bug.
5858 * Bug Criteria:: Have you found a bug?
5859 * Bug Reporting:: How to report bugs
5863 @section Have you found a bug?
5864 @cindex bug criteria
5866 If you are not sure whether you have found a bug, here are some guidelines:
5869 @cindex fatal signal
5870 @cindex assembler crash
5871 @cindex crash of assembler
5873 If the assembler gets a fatal signal, for any input whatever, that is a
5874 @command{@value{AS}} bug. Reliable assemblers never crash.
5876 @cindex error on valid input
5878 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5880 @cindex invalid input
5882 If @command{@value{AS}} does not produce an error message for invalid input, that
5883 is a bug. However, you should note that your idea of ``invalid input'' might
5884 be our idea of ``an extension'' or ``support for traditional practice''.
5887 If you are an experienced user of assemblers, your suggestions for improvement
5888 of @command{@value{AS}} are welcome in any case.
5892 @section How to report bugs
5894 @cindex assembler bugs, reporting
5896 A number of companies and individuals offer support for @sc{gnu} products. If
5897 you obtained @command{@value{AS}} from a support organization, we recommend you
5898 contact that organization first.
5900 You can find contact information for many support companies and
5901 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5904 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5905 to @samp{bug-binutils@@gnu.org}.
5907 The fundamental principle of reporting bugs usefully is this:
5908 @strong{report all the facts}. If you are not sure whether to state a
5909 fact or leave it out, state it!
5911 Often people omit facts because they think they know what causes the problem
5912 and assume that some details do not matter. Thus, you might assume that the
5913 name of a symbol you use in an example does not matter. Well, probably it does
5914 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5915 happens to fetch from the location where that name is stored in memory;
5916 perhaps, if the name were different, the contents of that location would fool
5917 the assembler into doing the right thing despite the bug. Play it safe and
5918 give a specific, complete example. That is the easiest thing for you to do,
5919 and the most helpful.
5921 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5922 it is new to us. Therefore, always write your bug reports on the assumption
5923 that the bug has not been reported previously.
5925 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5926 bell?'' Those bug reports are useless, and we urge everyone to
5927 @emph{refuse to respond to them} except to chide the sender to report
5930 To enable us to fix the bug, you should include all these things:
5934 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5935 it with the @samp{--version} argument.
5937 Without this, we will not know whether there is any point in looking for
5938 the bug in the current version of @command{@value{AS}}.
5941 Any patches you may have applied to the @command{@value{AS}} source.
5944 The type of machine you are using, and the operating system name and
5948 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5952 The command arguments you gave the assembler to assemble your example and
5953 observe the bug. To guarantee you will not omit something important, list them
5954 all. A copy of the Makefile (or the output from make) is sufficient.
5956 If we were to try to guess the arguments, we would probably guess wrong
5957 and then we might not encounter the bug.
5960 A complete input file that will reproduce the bug. If the bug is observed when
5961 the assembler is invoked via a compiler, send the assembler source, not the
5962 high level language source. Most compilers will produce the assembler source
5963 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5964 the options @samp{-v --save-temps}; this will save the assembler source in a
5965 file with an extension of @file{.s}, and also show you exactly how
5966 @command{@value{AS}} is being run.
5969 A description of what behavior you observe that you believe is
5970 incorrect. For example, ``It gets a fatal signal.''
5972 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5973 will certainly notice it. But if the bug is incorrect output, we might not
5974 notice unless it is glaringly wrong. You might as well not give us a chance to
5977 Even if the problem you experience is a fatal signal, you should still say so
5978 explicitly. Suppose something strange is going on, such as, your copy of
5979 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5980 library on your system. (This has happened!) Your copy might crash and ours
5981 would not. If you told us to expect a crash, then when ours fails to crash, we
5982 would know that the bug was not happening for us. If you had not told us to
5983 expect a crash, then we would not be able to draw any conclusion from our
5987 If you wish to suggest changes to the @command{@value{AS}} source, send us context
5988 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5989 option. Always send diffs from the old file to the new file. If you even
5990 discuss something in the @command{@value{AS}} source, refer to it by context, not
5993 The line numbers in our development sources will not match those in your
5994 sources. Your line numbers would convey no useful information to us.
5997 Here are some things that are not necessary:
6001 A description of the envelope of the bug.
6003 Often people who encounter a bug spend a lot of time investigating
6004 which changes to the input file will make the bug go away and which
6005 changes will not affect it.
6007 This is often time consuming and not very useful, because the way we
6008 will find the bug is by running a single example under the debugger
6009 with breakpoints, not by pure deduction from a series of examples.
6010 We recommend that you save your time for something else.
6012 Of course, if you can find a simpler example to report @emph{instead}
6013 of the original one, that is a convenience for us. Errors in the
6014 output will be easier to spot, running under the debugger will take
6015 less time, and so on.
6017 However, simplification is not vital; if you do not want to do this,
6018 report the bug anyway and send us the entire test case you used.
6021 A patch for the bug.
6023 A patch for the bug does help us if it is a good one. But do not omit
6024 the necessary information, such as the test case, on the assumption that
6025 a patch is all we need. We might see problems with your patch and decide
6026 to fix the problem another way, or we might not understand it at all.
6028 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6029 construct an example that will make the program follow a certain path through
6030 the code. If you do not send us the example, we will not be able to construct
6031 one, so we will not be able to verify that the bug is fixed.
6033 And if we cannot understand what bug you are trying to fix, or why your
6034 patch should be an improvement, we will not install it. A test case will
6035 help us to understand.
6038 A guess about what the bug is or what it depends on.
6040 Such guesses are usually wrong. Even we cannot guess right about such
6041 things without first using the debugger to find the facts.
6044 @node Acknowledgements
6045 @chapter Acknowledgements
6047 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6048 it is not meant as a slight. We just don't know about it. Send mail to the
6049 maintainer, and we'll correct the situation. Currently
6051 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6053 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6056 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6057 information and the 68k series machines, most of the preprocessing pass, and
6058 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6060 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6061 many bug fixes, including merging support for several processors, breaking GAS
6062 up to handle multiple object file format back ends (including heavy rewrite,
6063 testing, an integration of the coff and b.out back ends), adding configuration
6064 including heavy testing and verification of cross assemblers and file splits
6065 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6066 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6067 port (including considerable amounts of reverse engineering), a SPARC opcode
6068 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6069 assertions and made them work, much other reorganization, cleanup, and lint.
6071 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6072 in format-specific I/O modules.
6074 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6075 has done much work with it since.
6077 The Intel 80386 machine description was written by Eliot Dresselhaus.
6079 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6081 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6082 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6084 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6085 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6086 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6087 support a.out format.
6089 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6090 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6091 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6092 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6095 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6096 simplified the configuration of which versions accept which directives. He
6097 updated the 68k machine description so that Motorola's opcodes always produced
6098 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6099 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6100 cross-compilation support, and one bug in relaxation that took a week and
6101 required the proverbial one-bit fix.
6103 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6104 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6105 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6106 PowerPC assembler, and made a few other minor patches.
6108 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6110 Hewlett-Packard contributed support for the HP9000/300.
6112 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6113 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6114 formats). This work was supported by both the Center for Software Science at
6115 the University of Utah and Cygnus Support.
6117 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6118 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6119 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6120 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6121 and some initial 64-bit support).
6123 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6125 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6126 support for openVMS/Alpha.
6128 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6131 Several engineers at Cygnus Support have also provided many small bug fixes and
6132 configuration enhancements.
6134 Many others have contributed large or small bugfixes and enhancements. If
6135 you have contributed significant work and are not mentioned on this list, and
6136 want to be, let us know. Some of the history has been lost; we are not
6137 intentionally leaving anyone out.
6139 @node GNU Free Documentation License
6140 @chapter GNU Free Documentation License
6142 GNU Free Documentation License
6144 Version 1.1, March 2000
6146 Copyright (C) 2000 Free Software Foundation, Inc.
6147 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6149 Everyone is permitted to copy and distribute verbatim copies
6150 of this license document, but changing it is not allowed.
6155 The purpose of this License is to make a manual, textbook, or other
6156 written document "free" in the sense of freedom: to assure everyone
6157 the effective freedom to copy and redistribute it, with or without
6158 modifying it, either commercially or noncommercially. Secondarily,
6159 this License preserves for the author and publisher a way to get
6160 credit for their work, while not being considered responsible for
6161 modifications made by others.
6163 This License is a kind of "copyleft", which means that derivative
6164 works of the document must themselves be free in the same sense. It
6165 complements the GNU General Public License, which is a copyleft
6166 license designed for free software.
6168 We have designed this License in order to use it for manuals for free
6169 software, because free software needs free documentation: a free
6170 program should come with manuals providing the same freedoms that the
6171 software does. But this License is not limited to software manuals;
6172 it can be used for any textual work, regardless of subject matter or
6173 whether it is published as a printed book. We recommend this License
6174 principally for works whose purpose is instruction or reference.
6177 1. APPLICABILITY AND DEFINITIONS
6179 This License applies to any manual or other work that contains a
6180 notice placed by the copyright holder saying it can be distributed
6181 under the terms of this License. The "Document", below, refers to any
6182 such manual or work. Any member of the public is a licensee, and is
6185 A "Modified Version" of the Document means any work containing the
6186 Document or a portion of it, either copied verbatim, or with
6187 modifications and/or translated into another language.
6189 A "Secondary Section" is a named appendix or a front-matter section of
6190 the Document that deals exclusively with the relationship of the
6191 publishers or authors of the Document to the Document's overall subject
6192 (or to related matters) and contains nothing that could fall directly
6193 within that overall subject. (For example, if the Document is in part a
6194 textbook of mathematics, a Secondary Section may not explain any
6195 mathematics.) The relationship could be a matter of historical
6196 connection with the subject or with related matters, or of legal,
6197 commercial, philosophical, ethical or political position regarding
6200 The "Invariant Sections" are certain Secondary Sections whose titles
6201 are designated, as being those of Invariant Sections, in the notice
6202 that says that the Document is released under this License.
6204 The "Cover Texts" are certain short passages of text that are listed,
6205 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6206 the Document is released under this License.
6208 A "Transparent" copy of the Document means a machine-readable copy,
6209 represented in a format whose specification is available to the
6210 general public, whose contents can be viewed and edited directly and
6211 straightforwardly with generic text editors or (for images composed of
6212 pixels) generic paint programs or (for drawings) some widely available
6213 drawing editor, and that is suitable for input to text formatters or
6214 for automatic translation to a variety of formats suitable for input
6215 to text formatters. A copy made in an otherwise Transparent file
6216 format whose markup has been designed to thwart or discourage
6217 subsequent modification by readers is not Transparent. A copy that is
6218 not "Transparent" is called "Opaque".
6220 Examples of suitable formats for Transparent copies include plain
6221 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6222 or XML using a publicly available DTD, and standard-conforming simple
6223 HTML designed for human modification. Opaque formats include
6224 PostScript, PDF, proprietary formats that can be read and edited only
6225 by proprietary word processors, SGML or XML for which the DTD and/or
6226 processing tools are not generally available, and the
6227 machine-generated HTML produced by some word processors for output
6230 The "Title Page" means, for a printed book, the title page itself,
6231 plus such following pages as are needed to hold, legibly, the material
6232 this License requires to appear in the title page. For works in
6233 formats which do not have any title page as such, "Title Page" means
6234 the text near the most prominent appearance of the work's title,
6235 preceding the beginning of the body of the text.
6240 You may copy and distribute the Document in any medium, either
6241 commercially or noncommercially, provided that this License, the
6242 copyright notices, and the license notice saying this License applies
6243 to the Document are reproduced in all copies, and that you add no other
6244 conditions whatsoever to those of this License. You may not use
6245 technical measures to obstruct or control the reading or further
6246 copying of the copies you make or distribute. However, you may accept
6247 compensation in exchange for copies. If you distribute a large enough
6248 number of copies you must also follow the conditions in section 3.
6250 You may also lend copies, under the same conditions stated above, and
6251 you may publicly display copies.
6254 3. COPYING IN QUANTITY
6256 If you publish printed copies of the Document numbering more than 100,
6257 and the Document's license notice requires Cover Texts, you must enclose
6258 the copies in covers that carry, clearly and legibly, all these Cover
6259 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6260 the back cover. Both covers must also clearly and legibly identify
6261 you as the publisher of these copies. The front cover must present
6262 the full title with all words of the title equally prominent and
6263 visible. You may add other material on the covers in addition.
6264 Copying with changes limited to the covers, as long as they preserve
6265 the title of the Document and satisfy these conditions, can be treated
6266 as verbatim copying in other respects.
6268 If the required texts for either cover are too voluminous to fit
6269 legibly, you should put the first ones listed (as many as fit
6270 reasonably) on the actual cover, and continue the rest onto adjacent
6273 If you publish or distribute Opaque copies of the Document numbering
6274 more than 100, you must either include a machine-readable Transparent
6275 copy along with each Opaque copy, or state in or with each Opaque copy
6276 a publicly-accessible computer-network location containing a complete
6277 Transparent copy of the Document, free of added material, which the
6278 general network-using public has access to download anonymously at no
6279 charge using public-standard network protocols. If you use the latter
6280 option, you must take reasonably prudent steps, when you begin
6281 distribution of Opaque copies in quantity, to ensure that this
6282 Transparent copy will remain thus accessible at the stated location
6283 until at least one year after the last time you distribute an Opaque
6284 copy (directly or through your agents or retailers) of that edition to
6287 It is requested, but not required, that you contact the authors of the
6288 Document well before redistributing any large number of copies, to give
6289 them a chance to provide you with an updated version of the Document.
6294 You may copy and distribute a Modified Version of the Document under
6295 the conditions of sections 2 and 3 above, provided that you release
6296 the Modified Version under precisely this License, with the Modified
6297 Version filling the role of the Document, thus licensing distribution
6298 and modification of the Modified Version to whoever possesses a copy
6299 of it. In addition, you must do these things in the Modified Version:
6301 A. Use in the Title Page (and on the covers, if any) a title distinct
6302 from that of the Document, and from those of previous versions
6303 (which should, if there were any, be listed in the History section
6304 of the Document). You may use the same title as a previous version
6305 if the original publisher of that version gives permission.
6306 B. List on the Title Page, as authors, one or more persons or entities
6307 responsible for authorship of the modifications in the Modified
6308 Version, together with at least five of the principal authors of the
6309 Document (all of its principal authors, if it has less than five).
6310 C. State on the Title page the name of the publisher of the
6311 Modified Version, as the publisher.
6312 D. Preserve all the copyright notices of the Document.
6313 E. Add an appropriate copyright notice for your modifications
6314 adjacent to the other copyright notices.
6315 F. Include, immediately after the copyright notices, a license notice
6316 giving the public permission to use the Modified Version under the
6317 terms of this License, in the form shown in the Addendum below.
6318 G. Preserve in that license notice the full lists of Invariant Sections
6319 and required Cover Texts given in the Document's license notice.
6320 H. Include an unaltered copy of this License.
6321 I. Preserve the section entitled "History", and its title, and add to
6322 it an item stating at least the title, year, new authors, and
6323 publisher of the Modified Version as given on the Title Page. If
6324 there is no section entitled "History" in the Document, create one
6325 stating the title, year, authors, and publisher of the Document as
6326 given on its Title Page, then add an item describing the Modified
6327 Version as stated in the previous sentence.
6328 J. Preserve the network location, if any, given in the Document for
6329 public access to a Transparent copy of the Document, and likewise
6330 the network locations given in the Document for previous versions
6331 it was based on. These may be placed in the "History" section.
6332 You may omit a network location for a work that was published at
6333 least four years before the Document itself, or if the original
6334 publisher of the version it refers to gives permission.
6335 K. In any section entitled "Acknowledgements" or "Dedications",
6336 preserve the section's title, and preserve in the section all the
6337 substance and tone of each of the contributor acknowledgements
6338 and/or dedications given therein.
6339 L. Preserve all the Invariant Sections of the Document,
6340 unaltered in their text and in their titles. Section numbers
6341 or the equivalent are not considered part of the section titles.
6342 M. Delete any section entitled "Endorsements". Such a section
6343 may not be included in the Modified Version.
6344 N. Do not retitle any existing section as "Endorsements"
6345 or to conflict in title with any Invariant Section.
6347 If the Modified Version includes new front-matter sections or
6348 appendices that qualify as Secondary Sections and contain no material
6349 copied from the Document, you may at your option designate some or all
6350 of these sections as invariant. To do this, add their titles to the
6351 list of Invariant Sections in the Modified Version's license notice.
6352 These titles must be distinct from any other section titles.
6354 You may add a section entitled "Endorsements", provided it contains
6355 nothing but endorsements of your Modified Version by various
6356 parties--for example, statements of peer review or that the text has
6357 been approved by an organization as the authoritative definition of a
6360 You may add a passage of up to five words as a Front-Cover Text, and a
6361 passage of up to 25 words as a Back-Cover Text, to the end of the list
6362 of Cover Texts in the Modified Version. Only one passage of
6363 Front-Cover Text and one of Back-Cover Text may be added by (or
6364 through arrangements made by) any one entity. If the Document already
6365 includes a cover text for the same cover, previously added by you or
6366 by arrangement made by the same entity you are acting on behalf of,
6367 you may not add another; but you may replace the old one, on explicit
6368 permission from the previous publisher that added the old one.
6370 The author(s) and publisher(s) of the Document do not by this License
6371 give permission to use their names for publicity for or to assert or
6372 imply endorsement of any Modified Version.
6375 5. COMBINING DOCUMENTS
6377 You may combine the Document with other documents released under this
6378 License, under the terms defined in section 4 above for modified
6379 versions, provided that you include in the combination all of the
6380 Invariant Sections of all of the original documents, unmodified, and
6381 list them all as Invariant Sections of your combined work in its
6384 The combined work need only contain one copy of this License, and
6385 multiple identical Invariant Sections may be replaced with a single
6386 copy. If there are multiple Invariant Sections with the same name but
6387 different contents, make the title of each such section unique by
6388 adding at the end of it, in parentheses, the name of the original
6389 author or publisher of that section if known, or else a unique number.
6390 Make the same adjustment to the section titles in the list of
6391 Invariant Sections in the license notice of the combined work.
6393 In the combination, you must combine any sections entitled "History"
6394 in the various original documents, forming one section entitled
6395 "History"; likewise combine any sections entitled "Acknowledgements",
6396 and any sections entitled "Dedications". You must delete all sections
6397 entitled "Endorsements."
6400 6. COLLECTIONS OF DOCUMENTS
6402 You may make a collection consisting of the Document and other documents
6403 released under this License, and replace the individual copies of this
6404 License in the various documents with a single copy that is included in
6405 the collection, provided that you follow the rules of this License for
6406 verbatim copying of each of the documents in all other respects.
6408 You may extract a single document from such a collection, and distribute
6409 it individually under this License, provided you insert a copy of this
6410 License into the extracted document, and follow this License in all
6411 other respects regarding verbatim copying of that document.
6414 7. AGGREGATION WITH INDEPENDENT WORKS
6416 A compilation of the Document or its derivatives with other separate
6417 and independent documents or works, in or on a volume of a storage or
6418 distribution medium, does not as a whole count as a Modified Version
6419 of the Document, provided no compilation copyright is claimed for the
6420 compilation. Such a compilation is called an "aggregate", and this
6421 License does not apply to the other self-contained works thus compiled
6422 with the Document, on account of their being thus compiled, if they
6423 are not themselves derivative works of the Document.
6425 If the Cover Text requirement of section 3 is applicable to these
6426 copies of the Document, then if the Document is less than one quarter
6427 of the entire aggregate, the Document's Cover Texts may be placed on
6428 covers that surround only the Document within the aggregate.
6429 Otherwise they must appear on covers around the whole aggregate.
6434 Translation is considered a kind of modification, so you may
6435 distribute translations of the Document under the terms of section 4.
6436 Replacing Invariant Sections with translations requires special
6437 permission from their copyright holders, but you may include
6438 translations of some or all Invariant Sections in addition to the
6439 original versions of these Invariant Sections. You may include a
6440 translation of this License provided that you also include the
6441 original English version of this License. In case of a disagreement
6442 between the translation and the original English version of this
6443 License, the original English version will prevail.
6448 You may not copy, modify, sublicense, or distribute the Document except
6449 as expressly provided for under this License. Any other attempt to
6450 copy, modify, sublicense or distribute the Document is void, and will
6451 automatically terminate your rights under this License. However,
6452 parties who have received copies, or rights, from you under this
6453 License will not have their licenses terminated so long as such
6454 parties remain in full compliance.
6457 10. FUTURE REVISIONS OF THIS LICENSE
6459 The Free Software Foundation may publish new, revised versions
6460 of the GNU Free Documentation License from time to time. Such new
6461 versions will be similar in spirit to the present version, but may
6462 differ in detail to address new problems or concerns. See
6463 http://www.gnu.org/copyleft/.
6465 Each version of the License is given a distinguishing version number.
6466 If the Document specifies that a particular numbered version of this
6467 License "or any later version" applies to it, you have the option of
6468 following the terms and conditions either of that specified version or
6469 of any later version that has been published (not as a draft) by the
6470 Free Software Foundation. If the Document does not specify a version
6471 number of this License, you may choose any version ever published (not
6472 as a draft) by the Free Software Foundation.
6475 ADDENDUM: How to use this License for your documents
6477 To use this License in a document you have written, include a copy of
6478 the License in the document and put the following copyright and
6479 license notices just after the title page:
6482 Copyright (c) YEAR YOUR NAME.
6483 Permission is granted to copy, distribute and/or modify this document
6484 under the terms of the GNU Free Documentation License, Version 1.1
6485 or any later version published by the Free Software Foundation;
6486 with the Invariant Sections being LIST THEIR TITLES, with the
6487 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6488 A copy of the license is included in the section entitled "GNU
6489 Free Documentation License".
6492 If you have no Invariant Sections, write "with no Invariant Sections"
6493 instead of saying which ones are invariant. If you have no
6494 Front-Cover Texts, write "no Front-Cover Texts" instead of
6495 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6497 If your document contains nontrivial examples of program code, we
6498 recommend releasing these examples in parallel under your choice of
6499 free software license, such as the GNU General Public License,
6500 to permit their use in free software.
nant's projects / dragonfly.git / blob