as.texinfo revision 1.5
1\input texinfo @c -*-Texinfo-*- 2@c Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 2000 3@c Free Software Foundation, Inc. 4@c UPDATE!! On future updates-- 5@c (1) check for new machine-dep cmdline options in 6@c md_parse_option definitions in config/tc-*.c 7@c (2) for platform-specific directives, examine md_pseudo_op 8@c in config/tc-*.c 9@c (3) for object-format specific directives, examine obj_pseudo_op 10@c in config/obj-*.c 11@c (4) portable directives in potable[] in read.c 12@c %**start of header 13@setfilename as.info 14@c ---config--- 15@c defaults, config file may override: 16@set have-stabs 17@c --- 18@include asconfig.texi 19@include gasver.texi 20@c --- 21@c common OR combinations of conditions 22@ifset AOUT 23@set aout-bout 24@end ifset 25@ifset ARM/Thumb 26@set ARM 27@end ifset 28@ifset BOUT 29@set aout-bout 30@end ifset 31@ifset H8/300 32@set H8 33@end ifset 34@ifset H8/500 35@set H8 36@end ifset 37@ifset SH 38@set H8 39@end ifset 40@ifset HPPA 41@set abnormal-separator 42@end ifset 43@c ------------ 44@ifset GENERIC 45@settitle Using @value{AS} 46@end ifset 47@ifclear GENERIC 48@settitle Using @value{AS} (@value{TARGET}) 49@end ifclear 50@setchapternewpage odd 51@c %**end of header 52 53@c @smallbook 54@c @set SMALL 55@c WARE! Some of the machine-dependent sections contain tables of machine 56@c instructions. Except in multi-column format, these tables look silly. 57@c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so 58@c the multi-col format is faked within @example sections. 59@c 60@c Again unfortunately, the natural size that fits on a page, for these tables, 61@c is different depending on whether or not smallbook is turned on. 62@c This matters, because of order: text flow switches columns at each page 63@c break. 64@c 65@c The format faked in this source works reasonably well for smallbook, 66@c not well for the default large-page format. This manual expects that if you 67@c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the 68@c tables in question. You can turn on one without the other at your 69@c discretion, of course. 70@ifinfo 71@set SMALL 72@c the insn tables look just as silly in info files regardless of smallbook, 73@c might as well show 'em anyways. 74@end ifinfo 75 76@ifinfo 77@format 78START-INFO-DIR-ENTRY 79* As: (as). The GNU assembler. 80END-INFO-DIR-ENTRY 81@end format 82@end ifinfo 83 84@finalout 85@syncodeindex ky cp 86 87@ifinfo 88This file documents the GNU Assembler "@value{AS}". 89 90Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc. 91 92Permission is granted to make and distribute verbatim copies of 93this manual provided the copyright notice and this permission notice 94are preserved on all copies. 95 96@ignore 97Permission is granted to process this file through Tex and print the 98results, provided the printed document carries copying permission 99notice identical to this one except for the removal of this paragraph 100(this paragraph not being relevant to the printed manual). 101 102@end ignore 103Permission is granted to copy and distribute modified versions of this manual 104under the conditions for verbatim copying, provided that the entire resulting 105derived work is distributed under the terms of a permission notice identical to 106this one. 107 108Permission is granted to copy and distribute translations of this manual 109into another language, under the above conditions for modified versions. 110@end ifinfo 111 112@titlepage 113@title Using @value{AS} 114@subtitle The @sc{gnu} Assembler 115@ifclear GENERIC 116@subtitle for the @value{TARGET} family 117@end ifclear 118@sp 1 119@subtitle Version @value{VERSION} 120@sp 1 121@sp 13 122The Free Software Foundation Inc. thanks The Nice Computer 123Company of Australia for loaning Dean Elsner to write the 124first (Vax) version of @code{as} for Project @sc{gnu}. 125The proprietors, management and staff of TNCCA thank FSF for 126distracting the boss while they got some work 127done. 128@sp 3 129@author Dean Elsner, Jay Fenlason & friends 130@page 131@tex 132{\parskip=0pt 133\hfill {\it Using {\tt @value{AS}}}\par 134\hfill Edited by Cygnus Support\par 135} 136%"boxit" macro for figures: 137%Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3) 138\gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt 139 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil 140#2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline 141\gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box 142@end tex 143 144@vskip 0pt plus 1filll 145Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc. 146 147Permission is granted to make and distribute verbatim copies of 148this manual provided the copyright notice and this permission notice 149are preserved on all copies. 150 151Permission is granted to copy and distribute modified versions of this manual 152under the conditions for verbatim copying, provided that the entire resulting 153derived work is distributed under the terms of a permission notice identical to 154this one. 155 156Permission is granted to copy and distribute translations of this manual 157into another language, under the above conditions for modified versions. 158@end titlepage 159 160@ifinfo 161@node Top 162@top Using @value{AS} 163 164This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version 165@value{VERSION}. 166@ifclear GENERIC 167This version of the file describes @code{@value{AS}} configured to generate 168code for @value{TARGET} architectures. 169@end ifclear 170@menu 171* Overview:: Overview 172* Invoking:: Command-Line Options 173* Syntax:: Syntax 174* Sections:: Sections and Relocation 175* Symbols:: Symbols 176* Expressions:: Expressions 177* Pseudo Ops:: Assembler Directives 178* Machine Dependencies:: Machine Dependent Features 179* Reporting Bugs:: Reporting Bugs 180* Acknowledgements:: Who Did What 181* Index:: Index 182@end menu 183@end ifinfo 184 185@node Overview 186@chapter Overview 187@iftex 188This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}. 189@ifclear GENERIC 190This version of the manual describes @code{@value{AS}} configured to generate 191code for @value{TARGET} architectures. 192@end ifclear 193@end iftex 194 195@cindex invocation summary 196@cindex option summary 197@cindex summary of options 198Here is a brief summary of how to invoke @code{@value{AS}}. For details, 199@pxref{Invoking,,Comand-Line Options}. 200 201@c We don't use deffn and friends for the following because they seem 202@c to be limited to one line for the header. 203@smallexample 204@value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ] 205 [ -f ] [ --gstabs ] [ --gdwarf2 ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ] 206 [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ] 207 [ -version ] [ --version ] [ -W ] [ --warn ] [ --fatal-warnings ] 208 [ -w ] [ -x ] [ -Z ] 209@ifset A29K 210@c am29k has no machine-dependent assembler options 211@end ifset 212@ifset ARC 213 [ -mbig-endian | -mlittle-endian ] 214@end ifset 215@ifset ARM 216 [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]60 | 217 -m[arm]600 | -m[arm]610 | -m[arm]620 | -m[arm]7[t][[d]m[i]][fe] | -m[arm]70 | 218 -m[arm]700 | -m[arm]710[c] | -m[arm]7100 | -m[arm]7500 | -m[arm]8 | 219 -m[arm]810 | -m[arm]9 | -m[arm]920 | -m[arm]920t | -m[arm]9tdmi | 220 -mstrongarm | -mstrongarm110 | -mstrongarm1100 ] 221 [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t | 222 -m[arm]v5 | -[arm]v5t ] 223 [ -mthumb | -mall ] 224 [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ] 225 [ -EB | -EL ] 226 [ -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant ] 227 [ -mthumb-interwork ] 228 [ -moabi ] 229 [ -k ] 230@end ifset 231@ifset D10V 232 [ -O ] 233@end ifset 234@ifset D30V 235 [ -O | -n | -N ] 236@end ifset 237@ifset H8 238@c Hitachi family chips have no machine-dependent assembler options 239@end ifset 240@ifset HPPA 241@c HPPA has no machine-dependent assembler options (yet). 242@end ifset 243@ifset PJ 244 [ -mb | -me ] 245@end ifset 246@ifset SPARC 247@c The order here is important. See c-sparc.texi. 248 [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite 249 -Av8plus | -Av8plusa | -Av9 | -Av9a ] 250 [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ] 251@end ifset 252@ifset Z8000 253@c Z8000 has no machine-dependent assembler options 254@end ifset 255@ifset I960 256@c see md_parse_option in tc-i960.c 257 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ] 258 [ -b ] [ -no-relax ] 259@end ifset 260@ifset M680X0 261 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ] 262@end ifset 263@ifset MCORE 264 [ -jsri2bsr ] [ -sifilter ] [ -relax ] 265@end ifset 266@ifset MIPS 267 [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ] 268 [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -m4650 ] [ -no-m4650 ] 269 [ --trap ] [ --break ] 270 [ --emulation=@var{name} ] 271@end ifset 272 [ -- | @var{files} @dots{} ] 273@end smallexample 274 275@table @code 276@item -a[cdhlmns] 277Turn on listings, in any of a variety of ways: 278 279@table @code 280@item -ac 281omit false conditionals 282 283@item -ad 284omit debugging directives 285 286@item -ah 287include high-level source 288 289@item -al 290include assembly 291 292@item -am 293include macro expansions 294 295@item -an 296omit forms processing 297 298@item -as 299include symbols 300 301@item =file 302set the name of the listing file 303@end table 304 305You may combine these options; for example, use @samp{-aln} for assembly 306listing without forms processing. The @samp{=file} option, if used, must be 307the last one. By itself, @samp{-a} defaults to @samp{-ahls}. 308 309@item -D 310Ignored. This option is accepted for script compatibility with calls to 311other assemblers. 312 313@item --defsym @var{sym}=@var{value} 314Define the symbol @var{sym} to be @var{value} before assembling the input file. 315@var{value} must be an integer constant. As in C, a leading @samp{0x} 316indicates a hexadecimal value, and a leading @samp{0} indicates an octal value. 317 318@item -f 319``fast''---skip whitespace and comment preprocessing (assume source is 320compiler output). 321 322@item --gstabs 323Generate stabs debugging information for each assembler line. This 324may help debugging assembler code, if the debugger can handle it. 325 326@item --gdwarf2 327Generate DWARF2 debugging information for each assembler line. This 328may help debugging assembler code, if the debugger can handle it. 329 330@item --help 331Print a summary of the command line options and exit. 332 333@item -I @var{dir} 334Add directory @var{dir} to the search list for @code{.include} directives. 335 336@item -J 337Don't warn about signed overflow. 338 339@item -K 340@ifclear DIFF-TBL-KLUGE 341This option is accepted but has no effect on the @value{TARGET} family. 342@end ifclear 343@ifset DIFF-TBL-KLUGE 344Issue warnings when difference tables altered for long displacements. 345@end ifset 346 347@item -L 348@itemx --keep-locals 349Keep (in the symbol table) local symbols. On traditional a.out systems 350these start with @samp{L}, but different systems have different local 351label prefixes. 352 353@item -o @var{objfile} 354Name the object-file output from @code{@value{AS}} @var{objfile}. 355 356@item -R 357Fold the data section into the text section. 358 359@item --statistics 360Print the maximum space (in bytes) and total time (in seconds) used by 361assembly. 362 363@item --strip-local-absolute 364Remove local absolute symbols from the outgoing symbol table. 365 366@item -v 367@itemx -version 368Print the @code{as} version. 369 370@item --version 371Print the @code{as} version and exit. 372 373@item -W 374@itemx --no-warn 375Suppress warning messages. 376 377@item --fatal-warnings 378Treat warnings as errors. 379 380@item --warn 381Don't suppress warning messages or treat them as errors. 382 383@item -w 384Ignored. 385 386@item -x 387Ignored. 388 389@item -Z 390Generate an object file even after errors. 391 392@item -- | @var{files} @dots{} 393Standard input, or source files to assemble. 394 395@end table 396 397@ifset ARC 398The following options are available when @value{AS} is configured for 399an ARC processor. 400 401@table @code 402 403@cindex ARC endianness 404@cindex endianness, ARC 405@cindex big endian output, ARC 406@item -mbig-endian 407Generate ``big endian'' format output. 408 409@cindex little endian output, ARC 410@item -mlittle-endian 411Generate ``little endian'' format output. 412 413@end table 414@end ifset 415 416@ifset ARM 417The following options are available when @value{AS} is configured for the ARM 418processor family. 419 420@table @code 421@item -m[arm][1|2|3|6|7|8|9][...] 422Specify which ARM processor variant is the target. 423@item -m[arm]v[2|2a|3|3m|4|4t|5|5t] 424Specify which ARM architecture variant is used by the target. 425@item -mthumb | -mall 426Enable or disable Thumb only instruction decoding. 427@item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu 428Select which Floating Point architcture is the target. 429@item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi 430Select which procedure calling convention is in use. 431@item -EB | -EL 432Select either big-endian (-EB) or little-endian (-EL) output. 433@item -mthumb-interwork 434Specify that the code has been generated with interworking between Thumb and 435ARM code in mind. 436@item -k 437Specify that PIC code has been generated. 438@end table 439@end ifset 440 441@ifset D10V 442The following options are available when @value{AS} is configured for 443a D10V processor. 444@table @code 445@cindex D10V optimization 446@cindex optimization, D10V 447@item -O 448Optimize output by parallelizing instructions. 449@end table 450@end ifset 451 452@ifset D30V 453The following options are available when @value{AS} is configured for a D30V 454processor. 455@table @code 456@cindex D30V optimization 457@cindex optimization, D30V 458@item -O 459Optimize output by parallelizing instructions. 460 461@cindex D30V nops 462@item -n 463Warn when nops are generated. 464 465@cindex D30V nops after 32-bit multiply 466@item -N 467Warn when a nop after a 32-bit multiply instruction is generated. 468@end table 469@end ifset 470 471@ifset I960 472The following options are available when @value{AS} is configured for the 473Intel 80960 processor. 474 475@table @code 476@item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC 477Specify which variant of the 960 architecture is the target. 478 479@item -b 480Add code to collect statistics about branches taken. 481 482@item -no-relax 483Do not alter compare-and-branch instructions for long displacements; 484error if necessary. 485 486@end table 487@end ifset 488 489 490@ifset M680X0 491The following options are available when @value{AS} is configured for the 492Motorola 68000 series. 493 494@table @code 495 496@item -l 497Shorten references to undefined symbols, to one word instead of two. 498 499@item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060 500@itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200 501Specify what processor in the 68000 family is the target. The default 502is normally the 68020, but this can be changed at configuration time. 503 504@item -m68881 | -m68882 | -mno-68881 | -mno-68882 505The target machine does (or does not) have a floating-point coprocessor. 506The default is to assume a coprocessor for 68020, 68030, and cpu32. Although 507the basic 68000 is not compatible with the 68881, a combination of the 508two can be specified, since it's possible to do emulation of the 509coprocessor instructions with the main processor. 510 511@item -m68851 | -mno-68851 512The target machine does (or does not) have a memory-management 513unit coprocessor. The default is to assume an MMU for 68020 and up. 514 515@end table 516@end ifset 517 518@ifset PJ 519The following options are available when @value{AS} is configured for 520a picoJava processor. 521 522@table @code 523 524@cindex PJ endianness 525@cindex endianness, PJ 526@cindex big endian output, PJ 527@item -mb 528Generate ``big endian'' format output. 529 530@cindex little endian output, PJ 531@item -ml 532Generate ``little endian'' format output. 533 534@end table 535@end ifset 536 537 538@ifset SPARC 539The following options are available when @code{@value{AS}} is configured 540for the SPARC architecture: 541 542@table @code 543@item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite 544@itemx -Av8plus | -Av8plusa | -Av9 | -Av9a 545Explicitly select a variant of the SPARC architecture. 546 547@samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. 548@samp{-Av9} and @samp{-Av9a} select a 64 bit environment. 549 550@samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with 551UltraSPARC extensions. 552 553@item -xarch=v8plus | -xarch=v8plusa 554For compatibility with the Solaris v9 assembler. These options are 555equivalent to -Av8plus and -Av8plusa, respectively. 556 557@item -bump 558Warn when the assembler switches to another architecture. 559@end table 560@end ifset 561 562@ifset MIPS 563The following options are available when @value{AS} is configured for 564a MIPS processor. 565 566@table @code 567@item -G @var{num} 568This option sets the largest size of an object that can be referenced 569implicitly with the @code{gp} register. It is only accepted for targets that 570use ECOFF format, such as a DECstation running Ultrix. The default value is 8. 571 572@cindex MIPS endianness 573@cindex endianness, MIPS 574@cindex big endian output, MIPS 575@item -EB 576Generate ``big endian'' format output. 577 578@cindex little endian output, MIPS 579@item -EL 580Generate ``little endian'' format output. 581 582@cindex MIPS ISA 583@item -mips1 584@itemx -mips2 585@itemx -mips3 586Generate code for a particular MIPS Instruction Set Architecture level. 587@samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors, 588@samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000} 589processor. 590 591@item -m4650 592@itemx -no-m4650 593Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept 594the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop} 595instructions around accesses to the @samp{HI} and @samp{LO} registers. 596@samp{-no-m4650} turns off this option. 597 598@item -mcpu=@var{CPU} 599Generate code for a particular MIPS cpu. This has little effect on the 600assembler, but it is passed by @code{@value{GCC}}. 601 602@cindex emulation 603@item --emulation=@var{name} 604This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured 605for some other target, in all respects, including output format (choosing 606between ELF and ECOFF only), handling of pseudo-opcodes which may generate 607debugging information or store symbol table information, and default 608endianness. The available configuration names are: @samp{mipsecoff}, 609@samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf}, 610@samp{mipsbelf}. The first two do not alter the default endianness from that 611of the primary target for which the assembler was configured; the others change 612the default to little- or big-endian as indicated by the @samp{b} or @samp{l} 613in the name. Using @samp{-EB} or @samp{-EL} will override the endianness 614selection in any case. 615 616This option is currently supported only when the primary target 617@code{@value{AS}} is configured for is a MIPS ELF or ECOFF target. 618Furthermore, the primary target or others specified with 619@samp{--enable-targets=@dots{}} at configuration time must include support for 620the other format, if both are to be available. For example, the Irix 5 621configuration includes support for both. 622 623Eventually, this option will support more configurations, with more 624fine-grained control over the assembler's behavior, and will be supported for 625more processors. 626 627@item -nocpp 628@code{@value{AS}} ignores this option. It is accepted for compatibility with 629the native tools. 630 631@need 900 632@item --trap 633@itemx --no-trap 634@itemx --break 635@itemx --no-break 636Control how to deal with multiplication overflow and division by zero. 637@samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception 638(and only work for Instruction Set Architecture level 2 and higher); 639@samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a 640break exception. 641@end table 642@end ifset 643 644@ifset MCORE 645The following options are available when @value{AS} is configured for 646an MCore processor. 647 648@table @code 649@item -jsri2bsr 650@itemx -nojsri2bsr 651Enable or disable the JSRI to BSR transformation. By default this is enabled. 652The command line option @samp{-nojsri2bsr} can be used to disable it. 653 654@item -sifilter 655@itemx -nosifilter 656Enable or disable the silicon filter behaviour. By default this is disabled. 657The default can be overidden by the @samp{-sifilter} command line option. 658 659@item -relax 660Alter jump instructions for long displacements. 661 662 663@end table 664@end ifset 665 666@menu 667* Manual:: Structure of this Manual 668* GNU Assembler:: The GNU Assembler 669* Object Formats:: Object File Formats 670* Command Line:: Command Line 671* Input Files:: Input Files 672* Object:: Output (Object) File 673* Errors:: Error and Warning Messages 674@end menu 675 676@node Manual 677@section Structure of this Manual 678 679@cindex manual, structure and purpose 680This manual is intended to describe what you need to know to use 681@sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including 682notation for symbols, constants, and expressions; the directives that 683@code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}. 684 685@ifclear GENERIC 686We also cover special features in the @value{TARGET} 687configuration of @code{@value{AS}}, including assembler directives. 688@end ifclear 689@ifset GENERIC 690This manual also describes some of the machine-dependent features of 691various flavors of the assembler. 692@end ifset 693 694@cindex machine instructions (not covered) 695On the other hand, this manual is @emph{not} intended as an introduction 696to programming in assembly language---let alone programming in general! 697In a similar vein, we make no attempt to introduce the machine 698architecture; we do @emph{not} describe the instruction set, standard 699mnemonics, registers or addressing modes that are standard to a 700particular architecture. 701@ifset GENERIC 702You may want to consult the manufacturer's 703machine architecture manual for this information. 704@end ifset 705@ifclear GENERIC 706@ifset H8/300 707For information on the H8/300 machine instruction set, see @cite{H8/300 708Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H, 709see @cite{H8/300H Series Programming Manual} (Hitachi). 710@end ifset 711@ifset H8/500 712For information on the H8/500 machine instruction set, see @cite{H8/500 713Series Programming Manual} (Hitachi M21T001). 714@end ifset 715@ifset SH 716For information on the Hitachi SH machine instruction set, see 717@cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.). 718@end ifset 719@ifset Z8000 720For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} 721@end ifset 722@end ifclear 723 724@c I think this is premature---doc@cygnus.com, 17jan1991 725@ignore 726Throughout this manual, we assume that you are running @dfn{GNU}, 727the portable operating system from the @dfn{Free Software 728Foundation, Inc.}. This restricts our attention to certain kinds of 729computer (in particular, the kinds of computers that @sc{gnu} can run on); 730once this assumption is granted examples and definitions need less 731qualification. 732 733@code{@value{AS}} is part of a team of programs that turn a high-level 734human-readable series of instructions into a low-level 735computer-readable series of instructions. Different versions of 736@code{@value{AS}} are used for different kinds of computer. 737@end ignore 738 739@c There used to be a section "Terminology" here, which defined 740@c "contents", "byte", "word", and "long". Defining "word" to any 741@c particular size is confusing when the .word directive may generate 16 742@c bits on one machine and 32 bits on another; in general, for the user 743@c version of this manual, none of these terms seem essential to define. 744@c They were used very little even in the former draft of the manual; 745@c this draft makes an effort to avoid them (except in names of 746@c directives). 747 748@node GNU Assembler 749@section The GNU Assembler 750 751@sc{gnu} @code{as} is really a family of assemblers. 752@ifclear GENERIC 753This manual describes @code{@value{AS}}, a member of that family which is 754configured for the @value{TARGET} architectures. 755@end ifclear 756If you use (or have used) the @sc{gnu} assembler on one architecture, you 757should find a fairly similar environment when you use it on another 758architecture. Each version has much in common with the others, 759including object file formats, most assembler directives (often called 760@dfn{pseudo-ops}) and assembler syntax.@refill 761 762@cindex purpose of @sc{gnu} assembler 763@code{@value{AS}} is primarily intended to assemble the output of the 764@sc{gnu} C compiler @code{@value{GCC}} for use by the linker 765@code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}} 766assemble correctly everything that other assemblers for the same 767machine would assemble. 768@ifset VAX 769Any exceptions are documented explicitly (@pxref{Machine Dependencies}). 770@end ifset 771@ifset M680X0 772@c This remark should appear in generic version of manual; assumption 773@c here is that generic version sets M680x0. 774This doesn't mean @code{@value{AS}} always uses the same syntax as another 775assembler for the same architecture; for example, we know of several 776incompatible versions of 680x0 assembly language syntax. 777@end ifset 778 779Unlike older assemblers, @code{@value{AS}} is designed to assemble a source 780program in one pass of the source file. This has a subtle impact on the 781@kbd{.org} directive (@pxref{Org,,@code{.org}}). 782 783@node Object Formats 784@section Object File Formats 785 786@cindex object file format 787The @sc{gnu} assembler can be configured to produce several alternative 788object file formats. For the most part, this does not affect how you 789write assembly language programs; but directives for debugging symbols 790are typically different in different file formats. @xref{Symbol 791Attributes,,Symbol Attributes}. 792@ifclear GENERIC 793@ifclear MULTI-OBJ 794On the @value{TARGET}, @code{@value{AS}} is configured to produce 795@value{OBJ-NAME} format object files. 796@end ifclear 797@c The following should exhaust all configs that set MULTI-OBJ, ideally 798@ifset A29K 799On the @value{TARGET}, @code{@value{AS}} can be configured to produce either 800@code{a.out} or COFF format object files. 801@end ifset 802@ifset I960 803On the @value{TARGET}, @code{@value{AS}} can be configured to produce either 804@code{b.out} or COFF format object files. 805@end ifset 806@ifset HPPA 807On the @value{TARGET}, @code{@value{AS}} can be configured to produce either 808SOM or ELF format object files. 809@end ifset 810@end ifclear 811 812@node Command Line 813@section Command Line 814 815@cindex command line conventions 816After the program name @code{@value{AS}}, the command line may contain 817options and file names. Options may appear in any order, and may be 818before, after, or between file names. The order of file names is 819significant. 820 821@cindex standard input, as input file 822@kindex -- 823@file{--} (two hyphens) by itself names the standard input file 824explicitly, as one of the files for @code{@value{AS}} to assemble. 825 826@cindex options, command line 827Except for @samp{--} any command line argument that begins with a 828hyphen (@samp{-}) is an option. Each option changes the behavior of 829@code{@value{AS}}. No option changes the way another option works. An 830option is a @samp{-} followed by one or more letters; the case of 831the letter is important. All options are optional. 832 833Some options expect exactly one file name to follow them. The file 834name may either immediately follow the option's letter (compatible 835with older assemblers) or it may be the next command argument (@sc{gnu} 836standard). These two command lines are equivalent: 837 838@smallexample 839@value{AS} -o my-object-file.o mumble.s 840@value{AS} -omy-object-file.o mumble.s 841@end smallexample 842 843@node Input Files 844@section Input Files 845 846@cindex input 847@cindex source program 848@cindex files, input 849We use the phrase @dfn{source program}, abbreviated @dfn{source}, to 850describe the program input to one run of @code{@value{AS}}. The program may 851be in one or more files; how the source is partitioned into files 852doesn't change the meaning of the source. 853 854@c I added "con" prefix to "catenation" just to prove I can overcome my 855@c APL training... doc@cygnus.com 856The source program is a concatenation of the text in all the files, in the 857order specified. 858 859Each time you run @code{@value{AS}} it assembles exactly one source 860program. The source program is made up of one or more files. 861(The standard input is also a file.) 862 863You give @code{@value{AS}} a command line that has zero or more input file 864names. The input files are read (from left file name to right). A 865command line argument (in any position) that has no special meaning 866is taken to be an input file name. 867 868If you give @code{@value{AS}} no file names it attempts to read one input file 869from the @code{@value{AS}} standard input, which is normally your terminal. You 870may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program 871to assemble. 872 873Use @samp{--} if you need to explicitly name the standard input file 874in your command line. 875 876If the source is empty, @code{@value{AS}} produces a small, empty object 877file. 878 879@subheading Filenames and Line-numbers 880 881@cindex input file linenumbers 882@cindex line numbers, in input files 883There are two ways of locating a line in the input file (or files) and 884either may be used in reporting error messages. One way refers to a line 885number in a physical file; the other refers to a line number in a 886``logical'' file. @xref{Errors, ,Error and Warning Messages}. 887 888@dfn{Physical files} are those files named in the command line given 889to @code{@value{AS}}. 890 891@dfn{Logical files} are simply names declared explicitly by assembler 892directives; they bear no relation to physical files. Logical file names help 893error messages reflect the original source file, when @code{@value{AS}} source 894is itself synthesized from other files. @code{@value{AS}} understands the 895@samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also 896@ref{File,,@code{.file}}. 897 898@node Object 899@section Output (Object) File 900 901@cindex object file 902@cindex output file 903@kindex a.out 904@kindex .o 905Every time you run @code{@value{AS}} it produces an output file, which is 906your assembly language program translated into numbers. This file 907is the object file. Its default name is 908@ifclear BOUT 909@code{a.out}. 910@end ifclear 911@ifset BOUT 912@ifset GENERIC 913@code{a.out}, or 914@end ifset 915@code{b.out} when @code{@value{AS}} is configured for the Intel 80960. 916@end ifset 917You can give it another name by using the @code{-o} option. Conventionally, 918object file names end with @file{.o}. The default name is used for historical 919reasons: older assemblers were capable of assembling self-contained programs 920directly into a runnable program. (For some formats, this isn't currently 921possible, but it can be done for the @code{a.out} format.) 922 923@cindex linker 924@kindex ld 925The object file is meant for input to the linker @code{@value{LD}}. It contains 926assembled program code, information to help @code{@value{LD}} integrate 927the assembled program into a runnable file, and (optionally) symbolic 928information for the debugger. 929 930@c link above to some info file(s) like the description of a.out. 931@c don't forget to describe @sc{gnu} info as well as Unix lossage. 932 933@node Errors 934@section Error and Warning Messages 935 936@cindex error messsages 937@cindex warning messages 938@cindex messages from assembler 939@code{@value{AS}} may write warnings and error messages to the standard error 940file (usually your terminal). This should not happen when a compiler 941runs @code{@value{AS}} automatically. Warnings report an assumption made so 942that @code{@value{AS}} could keep assembling a flawed program; errors report a 943grave problem that stops the assembly. 944 945@cindex format of warning messages 946Warning messages have the format 947 948@smallexample 949file_name:@b{NNN}:Warning Message Text 950@end smallexample 951 952@noindent 953@cindex line numbers, in warnings/errors 954(where @b{NNN} is a line number). If a logical file name has been given 955(@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of 956the current input file is used. If a logical line number was given 957@ifset GENERIC 958(@pxref{Line,,@code{.line}}) 959@end ifset 960@ifclear GENERIC 961@ifclear A29K 962(@pxref{Line,,@code{.line}}) 963@end ifclear 964@ifset A29K 965(@pxref{Ln,,@code{.ln}}) 966@end ifset 967@end ifclear 968then it is used to calculate the number printed, 969otherwise the actual line in the current source file is printed. The 970message text is intended to be self explanatory (in the grand Unix 971tradition). 972 973@cindex format of error messages 974Error messages have the format 975@smallexample 976file_name:@b{NNN}:FATAL:Error Message Text 977@end smallexample 978The file name and line number are derived as for warning 979messages. The actual message text may be rather less explanatory 980because many of them aren't supposed to happen. 981 982@node Invoking 983@chapter Command-Line Options 984 985@cindex options, all versions of assembler 986This chapter describes command-line options available in @emph{all} 987versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific 988@ifclear GENERIC 989to the @value{TARGET}. 990@end ifclear 991@ifset GENERIC 992to particular machine architectures. 993@end ifset 994 995If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2), 996you can use the @samp{-Wa} option to pass arguments through to the assembler. 997The assembler arguments must be separated from each other (and the @samp{-Wa}) 998by commas. For example: 999 1000@smallexample 1001gcc -c -g -O -Wa,-alh,-L file.c 1002@end smallexample 1003 1004@noindent 1005This passes two options to the assembler: @samp{-alh} (emit a listing to 1006standard output with with high-level and assembly source) and @samp{-L} (retain 1007local symbols in the symbol table). 1008 1009Usually you do not need to use this @samp{-Wa} mechanism, since many compiler 1010command-line options are automatically passed to the assembler by the compiler. 1011(You can call the @sc{gnu} compiler driver with the @samp{-v} option to see 1012precisely what options it passes to each compilation pass, including the 1013assembler.) 1014 1015@menu 1016* a:: -a[cdhlns] enable listings 1017* D:: -D for compatibility 1018* f:: -f to work faster 1019* I:: -I for .include search path 1020@ifclear DIFF-TBL-KLUGE 1021* K:: -K for compatibility 1022@end ifclear 1023@ifset DIFF-TBL-KLUGE 1024* K:: -K for difference tables 1025@end ifset 1026 1027* L:: -L to retain local labels 1028* M:: -M or --mri to assemble in MRI compatibility mode 1029* MD:: --MD for dependency tracking 1030* o:: -o to name the object file 1031* R:: -R to join data and text sections 1032* statistics:: --statistics to see statistics about assembly 1033* traditional-format:: --traditional-format for compatible output 1034* v:: -v to announce version 1035* W:: -W, --no-warn, --warn, --fatal-warnings to control warnings 1036* Z:: -Z to make object file even after errors 1037@end menu 1038 1039@node a 1040@section Enable Listings: @code{-a[cdhlns]} 1041 1042@kindex -a 1043@kindex -ac 1044@kindex -ad 1045@kindex -ah 1046@kindex -al 1047@kindex -an 1048@kindex -as 1049@cindex listings, enabling 1050@cindex assembly listings, enabling 1051 1052These options enable listing output from the assembler. By itself, 1053@samp{-a} requests high-level, assembly, and symbols listing. 1054You can use other letters to select specific options for the list: 1055@samp{-ah} requests a high-level language listing, 1056@samp{-al} requests an output-program assembly listing, and 1057@samp{-as} requests a symbol table listing. 1058High-level listings require that a compiler debugging option like 1059@samp{-g} be used, and that assembly listings (@samp{-al}) be requested 1060also. 1061 1062Use the @samp{-ac} option to omit false conditionals from a listing. Any lines 1063which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any 1064other conditional), or a true @code{.if} followed by an @code{.else}, will be 1065omitted from the listing. 1066 1067Use the @samp{-ad} option to omit debugging directives from the 1068listing. 1069 1070Once you have specified one of these options, you can further control 1071listing output and its appearance using the directives @code{.list}, 1072@code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and 1073@code{.sbttl}. 1074The @samp{-an} option turns off all forms processing. 1075If you do not request listing output with one of the @samp{-a} options, the 1076listing-control directives have no effect. 1077 1078The letters after @samp{-a} may be combined into one option, 1079@emph{e.g.}, @samp{-aln}. 1080 1081@node D 1082@section @code{-D} 1083 1084@kindex -D 1085This option has no effect whatsoever, but it is accepted to make it more 1086likely that scripts written for other assemblers also work with 1087@code{@value{AS}}. 1088 1089@node f 1090@section Work Faster: @code{-f} 1091 1092@kindex -f 1093@cindex trusted compiler 1094@cindex faster processing (@code{-f}) 1095@samp{-f} should only be used when assembling programs written by a 1096(trusted) compiler. @samp{-f} stops the assembler from doing whitespace 1097and comment preprocessing on 1098the input file(s) before assembling them. @xref{Preprocessing, 1099,Preprocessing}. 1100 1101@quotation 1102@emph{Warning:} if you use @samp{-f} when the files actually need to be 1103preprocessed (if they contain comments, for example), @code{@value{AS}} does 1104not work correctly. 1105@end quotation 1106 1107@node I 1108@section @code{.include} search path: @code{-I} @var{path} 1109 1110@kindex -I @var{path} 1111@cindex paths for @code{.include} 1112@cindex search path for @code{.include} 1113@cindex @code{include} directive search path 1114Use this option to add a @var{path} to the list of directories 1115@code{@value{AS}} searches for files specified in @code{.include} 1116directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as 1117many times as necessary to include a variety of paths. The current 1118working directory is always searched first; after that, @code{@value{AS}} 1119searches any @samp{-I} directories in the same order as they were 1120specified (left to right) on the command line. 1121 1122@node K 1123@section Difference Tables: @code{-K} 1124 1125@kindex -K 1126@ifclear DIFF-TBL-KLUGE 1127On the @value{TARGET} family, this option is allowed, but has no effect. It is 1128permitted for compatibility with the @sc{gnu} assembler on other platforms, 1129where it can be used to warn when the assembler alters the machine code 1130generated for @samp{.word} directives in difference tables. The @value{TARGET} 1131family does not have the addressing limitations that sometimes lead to this 1132alteration on other platforms. 1133@end ifclear 1134 1135@ifset DIFF-TBL-KLUGE 1136@cindex difference tables, warning 1137@cindex warning for altered difference tables 1138@code{@value{AS}} sometimes alters the code emitted for directives of the form 1139@samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}. 1140You can use the @samp{-K} option if you want a warning issued when this 1141is done. 1142@end ifset 1143 1144@node L 1145@section Include Local Labels: @code{-L} 1146 1147@kindex -L 1148@cindex local labels, retaining in output 1149Labels beginning with @samp{L} (upper case only) are called @dfn{local 1150labels}. @xref{Symbol Names}. Normally you do not see such labels when 1151debugging, because they are intended for the use of programs (like 1152compilers) that compose assembler programs, not for your notice. 1153Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not 1154normally debug with them. 1155 1156This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols 1157in the object file. Usually if you do this you also tell the linker 1158@code{@value{LD}} to preserve symbols whose names begin with @samp{L}. 1159 1160By default, a local label is any label beginning with @samp{L}, but each 1161target is allowed to redefine the local label prefix. 1162@ifset HPPA 1163On the HPPA local labels begin with @samp{L$}. 1164@end ifset 1165 1166@node M 1167@section Assemble in MRI Compatibility Mode: @code{-M} 1168 1169@kindex -M 1170@cindex MRI compatibility mode 1171The @code{-M} or @code{--mri} option selects MRI compatibility mode. This 1172changes the syntax and pseudo-op handling of @code{@value{AS}} to make it 1173compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the 1174configured target) assembler from Microtec Research. The exact nature of the 1175MRI syntax will not be documented here; see the MRI manuals for more 1176information. Note in particular that the handling of macros and macro 1177arguments is somewhat different. The purpose of this option is to permit 1178assembling existing MRI assembler code using @code{@value{AS}}. 1179 1180The MRI compatibility is not complete. Certain operations of the MRI assembler 1181depend upon its object file format, and can not be supported using other object 1182file formats. Supporting these would require enhancing each object file format 1183individually. These are: 1184 1185@itemize @bullet 1186@item global symbols in common section 1187 1188The m68k MRI assembler supports common sections which are merged by the linker. 1189Other object file formats do not support this. @code{@value{AS}} handles 1190common sections by treating them as a single common symbol. It permits local 1191symbols to be defined within a common section, but it can not support global 1192symbols, since it has no way to describe them. 1193 1194@item complex relocations 1195 1196The MRI assemblers support relocations against a negated section address, and 1197relocations which combine the start addresses of two or more sections. These 1198are not support by other object file formats. 1199 1200@item @code{END} pseudo-op specifying start address 1201 1202The MRI @code{END} pseudo-op permits the specification of a start address. 1203This is not supported by other object file formats. The start address may 1204instead be specified using the @code{-e} option to the linker, or in a linker 1205script. 1206 1207@item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops 1208 1209The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module 1210name to the output file. This is not supported by other object file formats. 1211 1212@item @code{ORG} pseudo-op 1213 1214The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given 1215address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op, 1216which changes the location within the current section. Absolute sections are 1217not supported by other object file formats. The address of a section may be 1218assigned within a linker script. 1219@end itemize 1220 1221There are some other features of the MRI assembler which are not supported by 1222@code{@value{AS}}, typically either because they are difficult or because they 1223seem of little consequence. Some of these may be supported in future releases. 1224 1225@itemize @bullet 1226 1227@item EBCDIC strings 1228 1229EBCDIC strings are not supported. 1230 1231@item packed binary coded decimal 1232 1233Packed binary coded decimal is not supported. This means that the @code{DC.P} 1234and @code{DCB.P} pseudo-ops are not supported. 1235 1236@item @code{FEQU} pseudo-op 1237 1238The m68k @code{FEQU} pseudo-op is not supported. 1239 1240@item @code{NOOBJ} pseudo-op 1241 1242The m68k @code{NOOBJ} pseudo-op is not supported. 1243 1244@item @code{OPT} branch control options 1245 1246The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, 1247@code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically 1248relaxes all branches, whether forward or backward, to an appropriate size, so 1249these options serve no purpose. 1250 1251@item @code{OPT} list control options 1252 1253The following m68k @code{OPT} list control options are ignored: @code{C}, 1254@code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, 1255@code{MEX}, @code{MC}, @code{MD}, @code{X}. 1256 1257@item other @code{OPT} options 1258 1259The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, 1260@code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. 1261 1262@item @code{OPT} @code{D} option is default 1263 1264The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. 1265@code{OPT NOD} may be used to turn it off. 1266 1267@item @code{XREF} pseudo-op. 1268 1269The m68k @code{XREF} pseudo-op is ignored. 1270 1271@item @code{.debug} pseudo-op 1272 1273The i960 @code{.debug} pseudo-op is not supported. 1274 1275@item @code{.extended} pseudo-op 1276 1277The i960 @code{.extended} pseudo-op is not supported. 1278 1279@item @code{.list} pseudo-op. 1280 1281The various options of the i960 @code{.list} pseudo-op are not supported. 1282 1283@item @code{.optimize} pseudo-op 1284 1285The i960 @code{.optimize} pseudo-op is not supported. 1286 1287@item @code{.output} pseudo-op 1288 1289The i960 @code{.output} pseudo-op is not supported. 1290 1291@item @code{.setreal} pseudo-op 1292 1293The i960 @code{.setreal} pseudo-op is not supported. 1294 1295@end itemize 1296 1297@node MD 1298@section Dependency tracking: @code{--MD} 1299 1300@kindex --MD 1301@cindex dependency tracking 1302@cindex make rules 1303 1304@code{@value{AS}} can generate a dependency file for the file it creates. This 1305file consists of a single rule suitable for @code{make} describing the 1306dependencies of the main source file. 1307 1308The rule is written to the file named in its argument. 1309 1310This feature is used in the automatic updating of makefiles. 1311 1312@node o 1313@section Name the Object File: @code{-o} 1314 1315@kindex -o 1316@cindex naming object file 1317@cindex object file name 1318There is always one object file output when you run @code{@value{AS}}. By 1319default it has the name 1320@ifset GENERIC 1321@ifset I960 1322@file{a.out} (or @file{b.out}, for Intel 960 targets only). 1323@end ifset 1324@ifclear I960 1325@file{a.out}. 1326@end ifclear 1327@end ifset 1328@ifclear GENERIC 1329@ifset I960 1330@file{b.out}. 1331@end ifset 1332@ifclear I960 1333@file{a.out}. 1334@end ifclear 1335@end ifclear 1336You use this option (which takes exactly one filename) to give the 1337object file a different name. 1338 1339Whatever the object file is called, @code{@value{AS}} overwrites any 1340existing file of the same name. 1341 1342@node R 1343@section Join Data and Text Sections: @code{-R} 1344 1345@kindex -R 1346@cindex data and text sections, joining 1347@cindex text and data sections, joining 1348@cindex joining text and data sections 1349@cindex merging text and data sections 1350@code{-R} tells @code{@value{AS}} to write the object file as if all 1351data-section data lives in the text section. This is only done at 1352the very last moment: your binary data are the same, but data 1353section parts are relocated differently. The data section part of 1354your object file is zero bytes long because all its bytes are 1355appended to the text section. (@xref{Sections,,Sections and Relocation}.) 1356 1357When you specify @code{-R} it would be possible to generate shorter 1358address displacements (because we do not have to cross between text and 1359data section). We refrain from doing this simply for compatibility with 1360older versions of @code{@value{AS}}. In future, @code{-R} may work this way. 1361 1362@ifset COFF 1363When @code{@value{AS}} is configured for COFF output, 1364this option is only useful if you use sections named @samp{.text} and 1365@samp{.data}. 1366@end ifset 1367 1368@ifset HPPA 1369@code{-R} is not supported for any of the HPPA targets. Using 1370@code{-R} generates a warning from @code{@value{AS}}. 1371@end ifset 1372 1373@node statistics 1374@section Display Assembly Statistics: @code{--statistics} 1375 1376@kindex --statistics 1377@cindex statistics, about assembly 1378@cindex time, total for assembly 1379@cindex space used, maximum for assembly 1380Use @samp{--statistics} to display two statistics about the resources used by 1381@code{@value{AS}}: the maximum amount of space allocated during the assembly 1382(in bytes), and the total execution time taken for the assembly (in @sc{cpu} 1383seconds). 1384 1385@node traditional-format 1386@section Compatible output: @code{--traditional-format} 1387 1388@kindex --traditional-format 1389For some targets, the output of @code{@value{AS}} is different in some ways 1390from the output of some existing assembler. This switch requests 1391@code{@value{AS}} to use the traditional format instead. 1392 1393For example, it disables the exception frame optimizations which 1394@code{@value{AS}} normally does by default on @code{@value{GCC}} output. 1395 1396@node v 1397@section Announce Version: @code{-v} 1398 1399@kindex -v 1400@kindex -version 1401@cindex assembler version 1402@cindex version of assembler 1403You can find out what version of as is running by including the 1404option @samp{-v} (which you can also spell as @samp{-version}) on the 1405command line. 1406 1407@node W 1408@section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings} 1409 1410@code{@value{AS}} should never give a warning or error message when 1411assembling compiler output. But programs written by people often 1412cause @code{@value{AS}} to give a warning that a particular assumption was 1413made. All such warnings are directed to the standard error file. 1414 1415@kindex @samp{-W} 1416@kindex @samp{--no-warn} 1417@cindex suppressing warnings 1418@cindex warnings, suppressing 1419If you use the @code{-W} and @code{--no-warn} options, no warnings are issued. 1420This only affects the warning messages: it does not change any particular of 1421how @code{@value{AS}} assembles your file. Errors, which stop the assembly, 1422are still reported. 1423 1424@kindex @samp{--fatal-warnings} 1425@cindex errors, caused by warnings 1426@cindex warnings, causing error 1427If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers 1428files that generate warnings to be in error. 1429 1430@kindex @samp{--warn} 1431@cindex warnings, switching on 1432You can switch these options off again by specifying @code{--warn}, which 1433causes warnings to be output as usual. 1434 1435@node Z 1436@section Generate Object File in Spite of Errors: @code{-Z} 1437@cindex object file, after errors 1438@cindex errors, continuing after 1439After an error message, @code{@value{AS}} normally produces no output. If for 1440some reason you are interested in object file output even after 1441@code{@value{AS}} gives an error message on your program, use the @samp{-Z} 1442option. If there are any errors, @code{@value{AS}} continues anyways, and 1443writes an object file after a final warning message of the form @samp{@var{n} 1444errors, @var{m} warnings, generating bad object file.} 1445 1446@node Syntax 1447@chapter Syntax 1448 1449@cindex machine-independent syntax 1450@cindex syntax, machine-independent 1451This chapter describes the machine-independent syntax allowed in a 1452source file. @code{@value{AS}} syntax is similar to what many other 1453assemblers use; it is inspired by the BSD 4.2 1454@ifclear VAX 1455assembler. 1456@end ifclear 1457@ifset VAX 1458assembler, except that @code{@value{AS}} does not assemble Vax bit-fields. 1459@end ifset 1460 1461@menu 1462* Preprocessing:: Preprocessing 1463* Whitespace:: Whitespace 1464* Comments:: Comments 1465* Symbol Intro:: Symbols 1466* Statements:: Statements 1467* Constants:: Constants 1468@end menu 1469 1470@node Preprocessing 1471@section Preprocessing 1472 1473@cindex preprocessing 1474The @code{@value{AS}} internal preprocessor: 1475@itemize @bullet 1476@cindex whitespace, removed by preprocessor 1477@item 1478adjusts and removes extra whitespace. It leaves one space or tab before 1479the keywords on a line, and turns any other whitespace on the line into 1480a single space. 1481 1482@cindex comments, removed by preprocessor 1483@item 1484removes all comments, replacing them with a single space, or an 1485appropriate number of newlines. 1486 1487@cindex constants, converted by preprocessor 1488@item 1489converts character constants into the appropriate numeric values. 1490@end itemize 1491 1492It does not do macro processing, include file handling, or 1493anything else you may get from your C compiler's preprocessor. You can 1494do include file processing with the @code{.include} directive 1495(@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver 1496to get other ``CPP'' style preprocessing, by giving the input file a 1497@samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of 1498Output, gcc.info, Using GNU CC}. 1499 1500Excess whitespace, comments, and character constants 1501cannot be used in the portions of the input text that are not 1502preprocessed. 1503 1504@cindex turning preprocessing on and off 1505@cindex preprocessing, turning on and off 1506@kindex #NO_APP 1507@kindex #APP 1508If the first line of an input file is @code{#NO_APP} or if you use the 1509@samp{-f} option, whitespace and comments are not removed from the input file. 1510Within an input file, you can ask for whitespace and comment removal in 1511specific portions of the by putting a line that says @code{#APP} before the 1512text that may contain whitespace or comments, and putting a line that says 1513@code{#NO_APP} after this text. This feature is mainly intend to support 1514@code{asm} statements in compilers whose output is otherwise free of comments 1515and whitespace. 1516 1517@node Whitespace 1518@section Whitespace 1519 1520@cindex whitespace 1521@dfn{Whitespace} is one or more blanks or tabs, in any order. 1522Whitespace is used to separate symbols, and to make programs neater for 1523people to read. Unless within character constants 1524(@pxref{Characters,,Character Constants}), any whitespace means the same 1525as exactly one space. 1526 1527@node Comments 1528@section Comments 1529 1530@cindex comments 1531There are two ways of rendering comments to @code{@value{AS}}. In both 1532cases the comment is equivalent to one space. 1533 1534Anything from @samp{/*} through the next @samp{*/} is a comment. 1535This means you may not nest these comments. 1536 1537@smallexample 1538/* 1539 The only way to include a newline ('\n') in a comment 1540 is to use this sort of comment. 1541*/ 1542 1543/* This sort of comment does not nest. */ 1544@end smallexample 1545 1546@cindex line comment character 1547Anything from the @dfn{line comment} character to the next newline 1548is considered a comment and is ignored. The line comment character is 1549@ifset A29K 1550@samp{;} for the AMD 29K family; 1551@end ifset 1552@ifset ARC 1553@samp{;} on the ARC; 1554@end ifset 1555@ifset ARM 1556@samp{@@} on the ARM; 1557@end ifset 1558@ifset H8/300 1559@samp{;} for the H8/300 family; 1560@end ifset 1561@ifset H8/500 1562@samp{!} for the H8/500 family; 1563@end ifset 1564@ifset HPPA 1565@samp{;} for the HPPA; 1566@end ifset 1567@ifset I960 1568@samp{#} on the i960; 1569@end ifset 1570@ifset PJ 1571@samp{;} for picoJava; 1572@end ifset 1573@ifset SH 1574@samp{!} for the Hitachi SH; 1575@end ifset 1576@ifset SPARC 1577@samp{!} on the SPARC; 1578@end ifset 1579@ifset M32R 1580@samp{#} on the m32r; 1581@end ifset 1582@ifset M680X0 1583@samp{|} on the 680x0; 1584@end ifset 1585@ifset VAX 1586@samp{#} on the Vax; 1587@end ifset 1588@ifset Z8000 1589@samp{!} for the Z8000; 1590@end ifset 1591@ifset V850 1592@samp{#} on the V850; 1593@end ifset 1594see @ref{Machine Dependencies}. @refill 1595@c FIXME What about i386, m88k, i860? 1596 1597@ifset GENERIC 1598On some machines there are two different line comment characters. One 1599character only begins a comment if it is the first non-whitespace character on 1600a line, while the other always begins a comment. 1601@end ifset 1602 1603@ifset V850 1604The V850 assembler also supports a double dash as starting a comment that 1605extends to the end of the line. 1606 1607@samp{--}; 1608@end ifset 1609 1610@kindex # 1611@cindex lines starting with @code{#} 1612@cindex logical line numbers 1613To be compatible with past assemblers, lines that begin with @samp{#} have a 1614special interpretation. Following the @samp{#} should be an absolute 1615expression (@pxref{Expressions}): the logical line number of the @emph{next} 1616line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a 1617new logical file name. The rest of the line, if any, should be whitespace. 1618 1619If the first non-whitespace characters on the line are not numeric, 1620the line is ignored. (Just like a comment.) 1621 1622@smallexample 1623 # This is an ordinary comment. 1624# 42-6 "new_file_name" # New logical file name 1625 # This is logical line # 36. 1626@end smallexample 1627This feature is deprecated, and may disappear from future versions 1628of @code{@value{AS}}. 1629 1630@node Symbol Intro 1631@section Symbols 1632 1633@cindex characters used in symbols 1634@ifclear SPECIAL-SYMS 1635A @dfn{symbol} is one or more characters chosen from the set of all 1636letters (both upper and lower case), digits and the three characters 1637@samp{_.$}. 1638@end ifclear 1639@ifset SPECIAL-SYMS 1640@ifclear GENERIC 1641@ifset H8 1642A @dfn{symbol} is one or more characters chosen from the set of all 1643letters (both upper and lower case), digits and the three characters 1644@samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in 1645symbol names.) 1646@end ifset 1647@end ifclear 1648@end ifset 1649@ifset GENERIC 1650On most machines, you can also use @code{$} in symbol names; exceptions 1651are noted in @ref{Machine Dependencies}. 1652@end ifset 1653No symbol may begin with a digit. Case is significant. 1654There is no length limit: all characters are significant. Symbols are 1655delimited by characters not in that set, or by the beginning of a file 1656(since the source program must end with a newline, the end of a file is 1657not a possible symbol delimiter). @xref{Symbols}. 1658@cindex length of symbols 1659 1660@node Statements 1661@section Statements 1662 1663@cindex statements, structure of 1664@cindex line separator character 1665@cindex statement separator character 1666@ifclear GENERIC 1667@ifclear abnormal-separator 1668A @dfn{statement} ends at a newline character (@samp{\n}) or at a 1669semicolon (@samp{;}). The newline or semicolon is considered part of 1670the preceding statement. Newlines and semicolons within character 1671constants are an exception: they do not end statements. 1672@end ifclear 1673@ifset abnormal-separator 1674@ifset A29K 1675A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at'' 1676sign (@samp{@@}). The newline or at sign is considered part of the 1677preceding statement. Newlines and at signs within character constants 1678are an exception: they do not end statements. 1679@end ifset 1680@ifset HPPA 1681A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation 1682point (@samp{!}). The newline or exclamation point is considered part of the 1683preceding statement. Newlines and exclamation points within character 1684constants are an exception: they do not end statements. 1685@end ifset 1686@ifset H8 1687A @dfn{statement} ends at a newline character (@samp{\n}); or (for the 1688H8/300) a dollar sign (@samp{$}); or (for the 1689Hitachi-SH or the 1690H8/500) a semicolon 1691(@samp{;}). The newline or separator character is considered part of 1692the preceding statement. Newlines and separators within character 1693constants are an exception: they do not end statements. 1694@end ifset 1695@end ifset 1696@end ifclear 1697@ifset GENERIC 1698A @dfn{statement} ends at a newline character (@samp{\n}) or line 1699separator character. (The line separator is usually @samp{;}, unless 1700this conflicts with the comment character; @pxref{Machine Dependencies}.) The 1701newline or separator character is considered part of the preceding 1702statement. Newlines and separators within character constants are an 1703exception: they do not end statements. 1704@end ifset 1705 1706@cindex newline, required at file end 1707@cindex EOF, newline must precede 1708It is an error to end any statement with end-of-file: the last 1709character of any input file should be a newline.@refill 1710 1711An empty statement is allowed, and may include whitespace. It is ignored. 1712 1713@cindex instructions and directives 1714@cindex directives and instructions 1715@c "key symbol" is not used elsewhere in the document; seems pedantic to 1716@c @defn{} it in that case, as was done previously... doc@cygnus.com, 1717@c 13feb91. 1718A statement begins with zero or more labels, optionally followed by a 1719key symbol which determines what kind of statement it is. The key 1720symbol determines the syntax of the rest of the statement. If the 1721symbol begins with a dot @samp{.} then the statement is an assembler 1722directive: typically valid for any computer. If the symbol begins with 1723a letter the statement is an assembly language @dfn{instruction}: it 1724assembles into a machine language instruction. 1725@ifset GENERIC 1726Different versions of @code{@value{AS}} for different computers 1727recognize different instructions. In fact, the same symbol may 1728represent a different instruction in a different computer's assembly 1729language.@refill 1730@end ifset 1731 1732@cindex @code{:} (label) 1733@cindex label (@code{:}) 1734A label is a symbol immediately followed by a colon (@code{:}). 1735Whitespace before a label or after a colon is permitted, but you may not 1736have whitespace between a label's symbol and its colon. @xref{Labels}. 1737 1738@ifset HPPA 1739For HPPA targets, labels need not be immediately followed by a colon, but 1740the definition of a label must begin in column zero. This also implies that 1741only one label may be defined on each line. 1742@end ifset 1743 1744@smallexample 1745label: .directive followed by something 1746another_label: # This is an empty statement. 1747 instruction operand_1, operand_2, @dots{} 1748@end smallexample 1749 1750@node Constants 1751@section Constants 1752 1753@cindex constants 1754A constant is a number, written so that its value is known by 1755inspection, without knowing any context. Like this: 1756@smallexample 1757@group 1758.byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. 1759.ascii "Ring the bell\7" # A string constant. 1760.octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. 1761.float 0f-314159265358979323846264338327\ 176295028841971.693993751E-40 # - pi, a flonum. 1763@end group 1764@end smallexample 1765 1766@menu 1767* Characters:: Character Constants 1768* Numbers:: Number Constants 1769@end menu 1770 1771@node Characters 1772@subsection Character Constants 1773 1774@cindex character constants 1775@cindex constants, character 1776There are two kinds of character constants. A @dfn{character} stands 1777for one character in one byte and its value may be used in 1778numeric expressions. String constants (properly called string 1779@emph{literals}) are potentially many bytes and their values may not be 1780used in arithmetic expressions. 1781 1782@menu 1783* Strings:: Strings 1784* Chars:: Characters 1785@end menu 1786 1787@node Strings 1788@subsubsection Strings 1789 1790@cindex string constants 1791@cindex constants, string 1792A @dfn{string} is written between double-quotes. It may contain 1793double-quotes or null characters. The way to get special characters 1794into a string is to @dfn{escape} these characters: precede them with 1795a backslash @samp{\} character. For example @samp{\\} represents 1796one backslash: the first @code{\} is an escape which tells 1797@code{@value{AS}} to interpret the second character literally as a backslash 1798(which prevents @code{@value{AS}} from recognizing the second @code{\} as an 1799escape character). The complete list of escapes follows. 1800 1801@cindex escape codes, character 1802@cindex character escape codes 1803@table @kbd 1804@c @item \a 1805@c Mnemonic for ACKnowledge; for ASCII this is octal code 007. 1806@c 1807@cindex @code{\b} (backspace character) 1808@cindex backspace (@code{\b}) 1809@item \b 1810Mnemonic for backspace; for ASCII this is octal code 010. 1811 1812@c @item \e 1813@c Mnemonic for EOText; for ASCII this is octal code 004. 1814@c 1815@cindex @code{\f} (formfeed character) 1816@cindex formfeed (@code{\f}) 1817@item \f 1818Mnemonic for FormFeed; for ASCII this is octal code 014. 1819 1820@cindex @code{\n} (newline character) 1821@cindex newline (@code{\n}) 1822@item \n 1823Mnemonic for newline; for ASCII this is octal code 012. 1824 1825@c @item \p 1826@c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. 1827@c 1828@cindex @code{\r} (carriage return character) 1829@cindex carriage return (@code{\r}) 1830@item \r 1831Mnemonic for carriage-Return; for ASCII this is octal code 015. 1832 1833@c @item \s 1834@c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with 1835@c other assemblers. 1836@c 1837@cindex @code{\t} (tab) 1838@cindex tab (@code{\t}) 1839@item \t 1840Mnemonic for horizontal Tab; for ASCII this is octal code 011. 1841 1842@c @item \v 1843@c Mnemonic for Vertical tab; for ASCII this is octal code 013. 1844@c @item \x @var{digit} @var{digit} @var{digit} 1845@c A hexadecimal character code. The numeric code is 3 hexadecimal digits. 1846@c 1847@cindex @code{\@var{ddd}} (octal character code) 1848@cindex octal character code (@code{\@var{ddd}}) 1849@item \ @var{digit} @var{digit} @var{digit} 1850An octal character code. The numeric code is 3 octal digits. 1851For compatibility with other Unix systems, 8 and 9 are accepted as digits: 1852for example, @code{\008} has the value 010, and @code{\009} the value 011. 1853 1854@cindex @code{\@var{xd...}} (hex character code) 1855@cindex hex character code (@code{\@var{xd...}}) 1856@item \@code{x} @var{hex-digits...} 1857A hex character code. All trailing hex digits are combined. Either upper or 1858lower case @code{x} works. 1859 1860@cindex @code{\\} (@samp{\} character) 1861@cindex backslash (@code{\\}) 1862@item \\ 1863Represents one @samp{\} character. 1864 1865@c @item \' 1866@c Represents one @samp{'} (accent acute) character. 1867@c This is needed in single character literals 1868@c (@xref{Characters,,Character Constants}.) to represent 1869@c a @samp{'}. 1870@c 1871@cindex @code{\"} (doublequote character) 1872@cindex doublequote (@code{\"}) 1873@item \" 1874Represents one @samp{"} character. Needed in strings to represent 1875this character, because an unescaped @samp{"} would end the string. 1876 1877@item \ @var{anything-else} 1878Any other character when escaped by @kbd{\} gives a warning, but 1879assembles as if the @samp{\} was not present. The idea is that if 1880you used an escape sequence you clearly didn't want the literal 1881interpretation of the following character. However @code{@value{AS}} has no 1882other interpretation, so @code{@value{AS}} knows it is giving you the wrong 1883code and warns you of the fact. 1884@end table 1885 1886Which characters are escapable, and what those escapes represent, 1887varies widely among assemblers. The current set is what we think 1888the BSD 4.2 assembler recognizes, and is a subset of what most C 1889compilers recognize. If you are in doubt, do not use an escape 1890sequence. 1891 1892@node Chars 1893@subsubsection Characters 1894 1895@cindex single character constant 1896@cindex character, single 1897@cindex constant, single character 1898A single character may be written as a single quote immediately 1899followed by that character. The same escapes apply to characters as 1900to strings. So if you want to write the character backslash, you 1901must write @kbd{'\\} where the first @code{\} escapes the second 1902@code{\}. As you can see, the quote is an acute accent, not a 1903grave accent. A newline 1904@ifclear GENERIC 1905@ifclear abnormal-separator 1906(or semicolon @samp{;}) 1907@end ifclear 1908@ifset abnormal-separator 1909@ifset A29K 1910(or at sign @samp{@@}) 1911@end ifset 1912@ifset H8 1913(or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the 1914Hitachi SH or 1915H8/500) 1916@end ifset 1917@end ifset 1918@end ifclear 1919immediately following an acute accent is taken as a literal character 1920and does not count as the end of a statement. The value of a character 1921constant in a numeric expression is the machine's byte-wide code for 1922that character. @code{@value{AS}} assumes your character code is ASCII: 1923@kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill 1924 1925@node Numbers 1926@subsection Number Constants 1927 1928@cindex constants, number 1929@cindex number constants 1930@code{@value{AS}} distinguishes three kinds of numbers according to how they 1931are stored in the target machine. @emph{Integers} are numbers that 1932would fit into an @code{int} in the C language. @emph{Bignums} are 1933integers, but they are stored in more than 32 bits. @emph{Flonums} 1934are floating point numbers, described below. 1935 1936@menu 1937* Integers:: Integers 1938* Bignums:: Bignums 1939* Flonums:: Flonums 1940@ifclear GENERIC 1941@ifset I960 1942* Bit Fields:: Bit Fields 1943@end ifset 1944@end ifclear 1945@end menu 1946 1947@node Integers 1948@subsubsection Integers 1949@cindex integers 1950@cindex constants, integer 1951 1952@cindex binary integers 1953@cindex integers, binary 1954A binary integer is @samp{0b} or @samp{0B} followed by zero or more of 1955the binary digits @samp{01}. 1956 1957@cindex octal integers 1958@cindex integers, octal 1959An octal integer is @samp{0} followed by zero or more of the octal 1960digits (@samp{01234567}). 1961 1962@cindex decimal integers 1963@cindex integers, decimal 1964A decimal integer starts with a non-zero digit followed by zero or 1965more digits (@samp{0123456789}). 1966 1967@cindex hexadecimal integers 1968@cindex integers, hexadecimal 1969A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or 1970more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. 1971 1972Integers have the usual values. To denote a negative integer, use 1973the prefix operator @samp{-} discussed under expressions 1974(@pxref{Prefix Ops,,Prefix Operators}). 1975 1976@node Bignums 1977@subsubsection Bignums 1978 1979@cindex bignums 1980@cindex constants, bignum 1981A @dfn{bignum} has the same syntax and semantics as an integer 1982except that the number (or its negative) takes more than 32 bits to 1983represent in binary. The distinction is made because in some places 1984integers are permitted while bignums are not. 1985 1986@node Flonums 1987@subsubsection Flonums 1988@cindex flonums 1989@cindex floating point numbers 1990@cindex constants, floating point 1991 1992@cindex precision, floating point 1993A @dfn{flonum} represents a floating point number. The translation is 1994indirect: a decimal floating point number from the text is converted by 1995@code{@value{AS}} to a generic binary floating point number of more than 1996sufficient precision. This generic floating point number is converted 1997to a particular computer's floating point format (or formats) by a 1998portion of @code{@value{AS}} specialized to that computer. 1999 2000A flonum is written by writing (in order) 2001@itemize @bullet 2002@item 2003The digit @samp{0}. 2004@ifset HPPA 2005(@samp{0} is optional on the HPPA.) 2006@end ifset 2007 2008@item 2009A letter, to tell @code{@value{AS}} the rest of the number is a flonum. 2010@ifset GENERIC 2011@kbd{e} is recommended. Case is not important. 2012@ignore 2013@c FIXME: verify if flonum syntax really this vague for most cases 2014(Any otherwise illegal letter works here, but that might be changed. Vax BSD 20154.2 assembler seems to allow any of @samp{defghDEFGH}.) 2016@end ignore 2017 2018On the H8/300, H8/500, 2019Hitachi SH, 2020and AMD 29K architectures, the letter must be 2021one of the letters @samp{DFPRSX} (in upper or lower case). 2022 2023On the ARC, the letter must be one of the letters @samp{DFRS} 2024(in upper or lower case). 2025 2026On the Intel 960 architecture, the letter must be 2027one of the letters @samp{DFT} (in upper or lower case). 2028 2029On the HPPA architecture, the letter must be @samp{E} (upper case only). 2030@end ifset 2031@ifclear GENERIC 2032@ifset A29K 2033One of the letters @samp{DFPRSX} (in upper or lower case). 2034@end ifset 2035@ifset ARC 2036One of the letters @samp{DFRS} (in upper or lower case). 2037@end ifset 2038@ifset H8 2039One of the letters @samp{DFPRSX} (in upper or lower case). 2040@end ifset 2041@ifset HPPA 2042The letter @samp{E} (upper case only). 2043@end ifset 2044@ifset I960 2045One of the letters @samp{DFT} (in upper or lower case). 2046@end ifset 2047@end ifclear 2048 2049@item 2050An optional sign: either @samp{+} or @samp{-}. 2051 2052@item 2053An optional @dfn{integer part}: zero or more decimal digits. 2054 2055@item 2056An optional @dfn{fractional part}: @samp{.} followed by zero 2057or more decimal digits. 2058 2059@item 2060An optional exponent, consisting of: 2061 2062@itemize @bullet 2063@item 2064An @samp{E} or @samp{e}. 2065@c I can't find a config where "EXP_CHARS" is other than 'eE', but in 2066@c principle this can perfectly well be different on different targets. 2067@item 2068Optional sign: either @samp{+} or @samp{-}. 2069@item 2070One or more decimal digits. 2071@end itemize 2072 2073@end itemize 2074 2075At least one of the integer part or the fractional part must be 2076present. The floating point number has the usual base-10 value. 2077 2078@code{@value{AS}} does all processing using integers. Flonums are computed 2079independently of any floating point hardware in the computer running 2080@code{@value{AS}}. 2081 2082@ifclear GENERIC 2083@ifset I960 2084@c Bit fields are written as a general facility but are also controlled 2085@c by a conditional-compilation flag---which is as of now (21mar91) 2086@c turned on only by the i960 config of GAS. 2087@node Bit Fields 2088@subsubsection Bit Fields 2089 2090@cindex bit fields 2091@cindex constants, bit field 2092You can also define numeric constants as @dfn{bit fields}. 2093specify two numbers separated by a colon--- 2094@example 2095@var{mask}:@var{value} 2096@end example 2097@noindent 2098@code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and 2099@var{value}. 2100 2101The resulting number is then packed 2102@ifset GENERIC 2103@c this conditional paren in case bit fields turned on elsewhere than 960 2104(in host-dependent byte order) 2105@end ifset 2106into a field whose width depends on which assembler directive has the 2107bit-field as its argument. Overflow (a result from the bitwise and 2108requiring more binary digits to represent) is not an error; instead, 2109more constants are generated, of the specified width, beginning with the 2110least significant digits.@refill 2111 2112The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, 2113@code{.short}, and @code{.word} accept bit-field arguments. 2114@end ifset 2115@end ifclear 2116 2117@node Sections 2118@chapter Sections and Relocation 2119@cindex sections 2120@cindex relocation 2121 2122@menu 2123* Secs Background:: Background 2124* Ld Sections:: Linker Sections 2125* As Sections:: Assembler Internal Sections 2126* Sub-Sections:: Sub-Sections 2127* bss:: bss Section 2128@end menu 2129 2130@node Secs Background 2131@section Background 2132 2133Roughly, a section is a range of addresses, with no gaps; all data 2134``in'' those addresses is treated the same for some particular purpose. 2135For example there may be a ``read only'' section. 2136 2137@cindex linker, and assembler 2138@cindex assembler, and linker 2139The linker @code{@value{LD}} reads many object files (partial programs) and 2140combines their contents to form a runnable program. When @code{@value{AS}} 2141emits an object file, the partial program is assumed to start at address 0. 2142@code{@value{LD}} assigns the final addresses for the partial program, so that 2143different partial programs do not overlap. This is actually an 2144oversimplification, but it suffices to explain how @code{@value{AS}} uses 2145sections. 2146 2147@code{@value{LD}} moves blocks of bytes of your program to their run-time 2148addresses. These blocks slide to their run-time addresses as rigid 2149units; their length does not change and neither does the order of bytes 2150within them. Such a rigid unit is called a @emph{section}. Assigning 2151run-time addresses to sections is called @dfn{relocation}. It includes 2152the task of adjusting mentions of object-file addresses so they refer to 2153the proper run-time addresses. 2154@ifset H8 2155For the H8/300 and H8/500, 2156and for the Hitachi SH, 2157@code{@value{AS}} pads sections if needed to 2158ensure they end on a word (sixteen bit) boundary. 2159@end ifset 2160 2161@cindex standard assembler sections 2162An object file written by @code{@value{AS}} has at least three sections, any 2163of which may be empty. These are named @dfn{text}, @dfn{data} and 2164@dfn{bss} sections. 2165 2166@ifset COFF 2167@ifset GENERIC 2168When it generates COFF output, 2169@end ifset 2170@code{@value{AS}} can also generate whatever other named sections you specify 2171using the @samp{.section} directive (@pxref{Section,,@code{.section}}). 2172If you do not use any directives that place output in the @samp{.text} 2173or @samp{.data} sections, these sections still exist, but are empty. 2174@end ifset 2175 2176@ifset HPPA 2177@ifset GENERIC 2178When @code{@value{AS}} generates SOM or ELF output for the HPPA, 2179@end ifset 2180@code{@value{AS}} can also generate whatever other named sections you 2181specify using the @samp{.space} and @samp{.subspace} directives. See 2182@cite{HP9000 Series 800 Assembly Language Reference Manual} 2183(HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} 2184assembler directives. 2185 2186@ifset SOM 2187Additionally, @code{@value{AS}} uses different names for the standard 2188text, data, and bss sections when generating SOM output. Program text 2189is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and 2190BSS into @samp{$BSS$}. 2191@end ifset 2192@end ifset 2193 2194Within the object file, the text section starts at address @code{0}, the 2195data section follows, and the bss section follows the data section. 2196 2197@ifset HPPA 2198When generating either SOM or ELF output files on the HPPA, the text 2199section starts at address @code{0}, the data section at address 2200@code{0x4000000}, and the bss section follows the data section. 2201@end ifset 2202 2203To let @code{@value{LD}} know which data changes when the sections are 2204relocated, and how to change that data, @code{@value{AS}} also writes to the 2205object file details of the relocation needed. To perform relocation 2206@code{@value{LD}} must know, each time an address in the object 2207file is mentioned: 2208@itemize @bullet 2209@item 2210Where in the object file is the beginning of this reference to 2211an address? 2212@item 2213How long (in bytes) is this reference? 2214@item 2215Which section does the address refer to? What is the numeric value of 2216@display 2217(@var{address}) @minus{} (@var{start-address of section})? 2218@end display 2219@item 2220Is the reference to an address ``Program-Counter relative''? 2221@end itemize 2222 2223@cindex addresses, format of 2224@cindex section-relative addressing 2225In fact, every address @code{@value{AS}} ever uses is expressed as 2226@display 2227(@var{section}) + (@var{offset into section}) 2228@end display 2229@noindent 2230Further, most expressions @code{@value{AS}} computes have this section-relative 2231nature. 2232@ifset SOM 2233(For some object formats, such as SOM for the HPPA, some expressions are 2234symbol-relative instead.) 2235@end ifset 2236 2237In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset 2238@var{N} into section @var{secname}.'' 2239 2240Apart from text, data and bss sections you need to know about the 2241@dfn{absolute} section. When @code{@value{LD}} mixes partial programs, 2242addresses in the absolute section remain unchanged. For example, address 2243@code{@{absolute 0@}} is ``relocated'' to run-time address 0 by 2244@code{@value{LD}}. Although the linker never arranges two partial programs' 2245data sections with overlapping addresses after linking, @emph{by definition} 2246their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one 2247part of a program is always the same address when the program is running as 2248address @code{@{absolute@ 239@}} in any other part of the program. 2249 2250The idea of sections is extended to the @dfn{undefined} section. Any 2251address whose section is unknown at assembly time is by definition 2252rendered @{undefined @var{U}@}---where @var{U} is filled in later. 2253Since numbers are always defined, the only way to generate an undefined 2254address is to mention an undefined symbol. A reference to a named 2255common block would be such a symbol: its value is unknown at assembly 2256time so it has section @emph{undefined}. 2257 2258By analogy the word @emph{section} is used to describe groups of sections in 2259the linked program. @code{@value{LD}} puts all partial programs' text 2260sections in contiguous addresses in the linked program. It is 2261customary to refer to the @emph{text section} of a program, meaning all 2262the addresses of all partial programs' text sections. Likewise for 2263data and bss sections. 2264 2265Some sections are manipulated by @code{@value{LD}}; others are invented for 2266use of @code{@value{AS}} and have no meaning except during assembly. 2267 2268@node Ld Sections 2269@section Linker Sections 2270@code{@value{LD}} deals with just four kinds of sections, summarized below. 2271 2272@table @strong 2273 2274@ifset COFF 2275@cindex named sections 2276@cindex sections, named 2277@item named sections 2278@end ifset 2279@ifset aout-bout 2280@cindex text section 2281@cindex data section 2282@itemx text section 2283@itemx data section 2284@end ifset 2285These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as 2286separate but equal sections. Anything you can say of one section is 2287true another. 2288@ifset aout-bout 2289When the program is running, however, it is 2290customary for the text section to be unalterable. The 2291text section is often shared among processes: it contains 2292instructions, constants and the like. The data section of a running 2293program is usually alterable: for example, C variables would be stored 2294in the data section. 2295@end ifset 2296 2297@cindex bss section 2298@item bss section 2299This section contains zeroed bytes when your program begins running. It 2300is used to hold unitialized variables or common storage. The length of 2301each partial program's bss section is important, but because it starts 2302out containing zeroed bytes there is no need to store explicit zero 2303bytes in the object file. The bss section was invented to eliminate 2304those explicit zeros from object files. 2305 2306@cindex absolute section 2307@item absolute section 2308Address 0 of this section is always ``relocated'' to runtime address 0. 2309This is useful if you want to refer to an address that @code{@value{LD}} must 2310not change when relocating. In this sense we speak of absolute 2311addresses being ``unrelocatable'': they do not change during relocation. 2312 2313@cindex undefined section 2314@item undefined section 2315This ``section'' is a catch-all for address references to objects not in 2316the preceding sections. 2317@c FIXME: ref to some other doc on obj-file formats could go here. 2318@end table 2319 2320@cindex relocation example 2321An idealized example of three relocatable sections follows. 2322@ifset COFF 2323The example uses the traditional section names @samp{.text} and @samp{.data}. 2324@end ifset 2325Memory addresses are on the horizontal axis. 2326 2327@c TEXI2ROFF-KILL 2328@ifinfo 2329@c END TEXI2ROFF-KILL 2330@smallexample 2331 +-----+----+--+ 2332partial program # 1: |ttttt|dddd|00| 2333 +-----+----+--+ 2334 2335 text data bss 2336 seg. seg. seg. 2337 2338 +---+---+---+ 2339partial program # 2: |TTT|DDD|000| 2340 +---+---+---+ 2341 2342 +--+---+-----+--+----+---+-----+~~ 2343linked program: | |TTT|ttttt| |dddd|DDD|00000| 2344 +--+---+-----+--+----+---+-----+~~ 2345 2346 addresses: 0 @dots{} 2347@end smallexample 2348@c TEXI2ROFF-KILL 2349@end ifinfo 2350@need 5000 2351@tex 2352 2353\line{\it Partial program \#1: \hfil} 2354\line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} 2355\line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} 2356 2357\line{\it Partial program \#2: \hfil} 2358\line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} 2359\line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} 2360 2361\line{\it linked program: \hfil} 2362\line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} 2363\line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt 2364ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt 2365DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} 2366 2367\line{\it addresses: \hfil} 2368\line{0\dots\hfil} 2369 2370@end tex 2371@c END TEXI2ROFF-KILL 2372 2373@node As Sections 2374@section Assembler Internal Sections 2375 2376@cindex internal assembler sections 2377@cindex sections in messages, internal 2378These sections are meant only for the internal use of @code{@value{AS}}. They 2379have no meaning at run-time. You do not really need to know about these 2380sections for most purposes; but they can be mentioned in @code{@value{AS}} 2381warning messages, so it might be helpful to have an idea of their 2382meanings to @code{@value{AS}}. These sections are used to permit the 2383value of every expression in your assembly language program to be a 2384section-relative address. 2385 2386@table @b 2387@cindex assembler internal logic error 2388@item ASSEMBLER-INTERNAL-LOGIC-ERROR! 2389An internal assembler logic error has been found. This means there is a 2390bug in the assembler. 2391 2392@cindex expr (internal section) 2393@item expr section 2394The assembler stores complex expression internally as combinations of 2395symbols. When it needs to represent an expression as a symbol, it puts 2396it in the expr section. 2397@c FIXME item debug 2398@c FIXME item transfer[t] vector preload 2399@c FIXME item transfer[t] vector postload 2400@c FIXME item register 2401@end table 2402 2403@node Sub-Sections 2404@section Sub-Sections 2405 2406@cindex numbered subsections 2407@cindex grouping data 2408@ifset aout-bout 2409Assembled bytes 2410@ifset COFF 2411conventionally 2412@end ifset 2413fall into two sections: text and data. 2414@end ifset 2415You may have separate groups of 2416@ifset GENERIC 2417data in named sections 2418@end ifset 2419@ifclear GENERIC 2420@ifclear aout-bout 2421data in named sections 2422@end ifclear 2423@ifset aout-bout 2424text or data 2425@end ifset 2426@end ifclear 2427that you want to end up near to each other in the object file, even though they 2428are not contiguous in the assembler source. @code{@value{AS}} allows you to 2429use @dfn{subsections} for this purpose. Within each section, there can be 2430numbered subsections with values from 0 to 8192. Objects assembled into the 2431same subsection go into the object file together with other objects in the same 2432subsection. For example, a compiler might want to store constants in the text 2433section, but might not want to have them interspersed with the program being 2434assembled. In this case, the compiler could issue a @samp{.text 0} before each 2435section of code being output, and a @samp{.text 1} before each group of 2436constants being output. 2437 2438Subsections are optional. If you do not use subsections, everything 2439goes in subsection number zero. 2440 2441@ifset GENERIC 2442Each subsection is zero-padded up to a multiple of four bytes. 2443(Subsections may be padded a different amount on different flavors 2444of @code{@value{AS}}.) 2445@end ifset 2446@ifclear GENERIC 2447@ifset H8 2448On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word 2449boundary (two bytes). 2450The same is true on the Hitachi SH. 2451@end ifset 2452@ifset I960 2453@c FIXME section padding (alignment)? 2454@c Rich Pixley says padding here depends on target obj code format; that 2455@c doesn't seem particularly useful to say without further elaboration, 2456@c so for now I say nothing about it. If this is a generic BFD issue, 2457@c these paragraphs might need to vanish from this manual, and be 2458@c discussed in BFD chapter of binutils (or some such). 2459@end ifset 2460@ifset A29K 2461On the AMD 29K family, no particular padding is added to section or 2462subsection sizes; @value{AS} forces no alignment on this platform. 2463@end ifset 2464@end ifclear 2465 2466Subsections appear in your object file in numeric order, lowest numbered 2467to highest. (All this to be compatible with other people's assemblers.) 2468The object file contains no representation of subsections; @code{@value{LD}} and 2469other programs that manipulate object files see no trace of them. 2470They just see all your text subsections as a text section, and all your 2471data subsections as a data section. 2472 2473To specify which subsection you want subsequent statements assembled 2474into, use a numeric argument to specify it, in a @samp{.text 2475@var{expression}} or a @samp{.data @var{expression}} statement. 2476@ifset COFF 2477@ifset GENERIC 2478When generating COFF output, you 2479@end ifset 2480@ifclear GENERIC 2481You 2482@end ifclear 2483can also use an extra subsection 2484argument with arbitrary named sections: @samp{.section @var{name}, 2485@var{expression}}. 2486@end ifset 2487@var{Expression} should be an absolute expression. 2488(@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0} 2489is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly 2490begins in @code{text 0}. For instance: 2491@smallexample 2492.text 0 # The default subsection is text 0 anyway. 2493.ascii "This lives in the first text subsection. *" 2494.text 1 2495.ascii "But this lives in the second text subsection." 2496.data 0 2497.ascii "This lives in the data section," 2498.ascii "in the first data subsection." 2499.text 0 2500.ascii "This lives in the first text section," 2501.ascii "immediately following the asterisk (*)." 2502@end smallexample 2503 2504Each section has a @dfn{location counter} incremented by one for every byte 2505assembled into that section. Because subsections are merely a convenience 2506restricted to @code{@value{AS}} there is no concept of a subsection location 2507counter. There is no way to directly manipulate a location counter---but the 2508@code{.align} directive changes it, and any label definition captures its 2509current value. The location counter of the section where statements are being 2510assembled is said to be the @dfn{active} location counter. 2511 2512@node bss 2513@section bss Section 2514 2515@cindex bss section 2516@cindex common variable storage 2517The bss section is used for local common variable storage. 2518You may allocate address space in the bss section, but you may 2519not dictate data to load into it before your program executes. When 2520your program starts running, all the contents of the bss 2521section are zeroed bytes. 2522 2523The @code{.lcomm} pseudo-op defines a symbol in the bss section; see 2524@ref{Lcomm,,@code{.lcomm}}. 2525 2526The @code{.comm} pseudo-op may be used to declare a common symbol, which is 2527another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}. 2528 2529@ifset GENERIC 2530When assembling for a target which supports multiple sections, such as ELF or 2531COFF, you may switch into the @code{.bss} section and define symbols as usual; 2532see @ref{Section,,@code{.section}}. You may only assemble zero values into the 2533section. Typically the section will only contain symbol definitions and 2534@code{.skip} directives (@pxref{Skip,,@code{.skip}}). 2535@end ifset 2536 2537@node Symbols 2538@chapter Symbols 2539 2540@cindex symbols 2541Symbols are a central concept: the programmer uses symbols to name 2542things, the linker uses symbols to link, and the debugger uses symbols 2543to debug. 2544 2545@quotation 2546@cindex debuggers, and symbol order 2547@emph{Warning:} @code{@value{AS}} does not place symbols in the object file in 2548the same order they were declared. This may break some debuggers. 2549@end quotation 2550 2551@menu 2552* Labels:: Labels 2553* Setting Symbols:: Giving Symbols Other Values 2554* Symbol Names:: Symbol Names 2555* Dot:: The Special Dot Symbol 2556* Symbol Attributes:: Symbol Attributes 2557@end menu 2558 2559@node Labels 2560@section Labels 2561 2562@cindex labels 2563A @dfn{label} is written as a symbol immediately followed by a colon 2564@samp{:}. The symbol then represents the current value of the 2565active location counter, and is, for example, a suitable instruction 2566operand. You are warned if you use the same symbol to represent two 2567different locations: the first definition overrides any other 2568definitions. 2569 2570@ifset HPPA 2571On the HPPA, the usual form for a label need not be immediately followed by a 2572colon, but instead must start in column zero. Only one label may be defined on 2573a single line. To work around this, the HPPA version of @code{@value{AS}} also 2574provides a special directive @code{.label} for defining labels more flexibly. 2575@end ifset 2576 2577@node Setting Symbols 2578@section Giving Symbols Other Values 2579 2580@cindex assigning values to symbols 2581@cindex symbol values, assigning 2582A symbol can be given an arbitrary value by writing a symbol, followed 2583by an equals sign @samp{=}, followed by an expression 2584(@pxref{Expressions}). This is equivalent to using the @code{.set} 2585directive. @xref{Set,,@code{.set}}. 2586 2587@node Symbol Names 2588@section Symbol Names 2589 2590@cindex symbol names 2591@cindex names, symbol 2592@ifclear SPECIAL-SYMS 2593Symbol names begin with a letter or with one of @samp{._}. On most 2594machines, you can also use @code{$} in symbol names; exceptions are 2595noted in @ref{Machine Dependencies}. That character may be followed by any 2596string of digits, letters, dollar signs (unless otherwise noted in 2597@ref{Machine Dependencies}), and underscores. 2598@end ifclear 2599@ifset A29K 2600For the AMD 29K family, @samp{?} is also allowed in the 2601body of a symbol name, though not at its beginning. 2602@end ifset 2603 2604@ifset SPECIAL-SYMS 2605@ifset H8 2606Symbol names begin with a letter or with one of @samp{._}. On the 2607Hitachi SH or the 2608H8/500, you can also use @code{$} in symbol names. That character may 2609be followed by any string of digits, letters, dollar signs (save on the 2610H8/300), and underscores. 2611@end ifset 2612@end ifset 2613 2614Case of letters is significant: @code{foo} is a different symbol name 2615than @code{Foo}. 2616 2617Each symbol has exactly one name. Each name in an assembly language program 2618refers to exactly one symbol. You may use that symbol name any number of times 2619in a program. 2620 2621@subheading Local Symbol Names 2622 2623@cindex local symbol names 2624@cindex symbol names, local 2625@cindex temporary symbol names 2626@cindex symbol names, temporary 2627Local symbols help compilers and programmers use names temporarily. 2628There are ten local symbol names, which are re-used throughout the 2629program. You may refer to them using the names @samp{0} @samp{1} 2630@dots{} @samp{9}. To define a local symbol, write a label of the form 2631@samp{@b{N}:} (where @b{N} represents any digit). To refer to the most 2632recent previous definition of that symbol write @samp{@b{N}b}, using the 2633same digit as when you defined the label. To refer to the next 2634definition of a local label, write @samp{@b{N}f}---where @b{N} gives you 2635a choice of 10 forward references. The @samp{b} stands for 2636``backwards'' and the @samp{f} stands for ``forwards''. 2637 2638Local symbols are not emitted by the current @sc{gnu} C compiler. 2639 2640There is no restriction on how you can use these labels, but 2641remember that at any point in the assembly you can refer to at most 264210 prior local labels and to at most 10 forward local labels. 2643 2644Local symbol names are only a notation device. They are immediately 2645transformed into more conventional symbol names before the assembler 2646uses them. The symbol names stored in the symbol table, appearing in 2647error messages and optionally emitted to the object file have these 2648parts: 2649 2650@table @code 2651@item L 2652All local labels begin with @samp{L}. Normally both @code{@value{AS}} and 2653@code{@value{LD}} forget symbols that start with @samp{L}. These labels are 2654used for symbols you are never intended to see. If you use the 2655@samp{-L} option then @code{@value{AS}} retains these symbols in the 2656object file. If you also instruct @code{@value{LD}} to retain these symbols, 2657you may use them in debugging. 2658 2659@item @var{digit} 2660If the label is written @samp{0:} then the digit is @samp{0}. 2661If the label is written @samp{1:} then the digit is @samp{1}. 2662And so on up through @samp{9:}. 2663 2664@item @kbd{C-A} 2665This unusual character is included so you do not accidentally invent 2666a symbol of the same name. The character has ASCII value 2667@samp{\001}. 2668 2669@item @emph{ordinal number} 2670This is a serial number to keep the labels distinct. The first 2671@samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the 2672number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:} 2673through @samp{9:}. 2674@end table 2675 2676For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th 2677@code{3:} is named @code{L3@kbd{C-A}44}. 2678 2679@node Dot 2680@section The Special Dot Symbol 2681 2682@cindex dot (symbol) 2683@cindex @code{.} (symbol) 2684@cindex current address 2685@cindex location counter 2686The special symbol @samp{.} refers to the current address that 2687@code{@value{AS}} is assembling into. Thus, the expression @samp{melvin: 2688.long .} defines @code{melvin} to contain its own address. 2689Assigning a value to @code{.} is treated the same as a @code{.org} 2690directive. Thus, the expression @samp{.=.+4} is the same as saying 2691@ifclear no-space-dir 2692@samp{.space 4}. 2693@end ifclear 2694@ifset no-space-dir 2695@ifset A29K 2696@samp{.block 4}. 2697@end ifset 2698@end ifset 2699 2700@node Symbol Attributes 2701@section Symbol Attributes 2702 2703@cindex symbol attributes 2704@cindex attributes, symbol 2705Every symbol has, as well as its name, the attributes ``Value'' and 2706``Type''. Depending on output format, symbols can also have auxiliary 2707attributes. 2708@ifset INTERNALS 2709The detailed definitions are in @file{a.out.h}. 2710@end ifset 2711 2712If you use a symbol without defining it, @code{@value{AS}} assumes zero for 2713all these attributes, and probably won't warn you. This makes the 2714symbol an externally defined symbol, which is generally what you 2715would want. 2716 2717@menu 2718* Symbol Value:: Value 2719* Symbol Type:: Type 2720@ifset aout-bout 2721@ifset GENERIC 2722* a.out Symbols:: Symbol Attributes: @code{a.out} 2723@end ifset 2724@ifclear GENERIC 2725@ifclear BOUT 2726* a.out Symbols:: Symbol Attributes: @code{a.out} 2727@end ifclear 2728@ifset BOUT 2729* a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} 2730@end ifset 2731@end ifclear 2732@end ifset 2733@ifset COFF 2734* COFF Symbols:: Symbol Attributes for COFF 2735@end ifset 2736@ifset SOM 2737* SOM Symbols:: Symbol Attributes for SOM 2738@end ifset 2739@end menu 2740 2741@node Symbol Value 2742@subsection Value 2743 2744@cindex value of a symbol 2745@cindex symbol value 2746The value of a symbol is (usually) 32 bits. For a symbol which labels a 2747location in the text, data, bss or absolute sections the value is the 2748number of addresses from the start of that section to the label. 2749Naturally for text, data and bss sections the value of a symbol changes 2750as @code{@value{LD}} changes section base addresses during linking. Absolute 2751symbols' values do not change during linking: that is why they are 2752called absolute. 2753 2754The value of an undefined symbol is treated in a special way. If it is 27550 then the symbol is not defined in this assembler source file, and 2756@code{@value{LD}} tries to determine its value from other files linked into the 2757same program. You make this kind of symbol simply by mentioning a symbol 2758name without defining it. A non-zero value represents a @code{.comm} 2759common declaration. The value is how much common storage to reserve, in 2760bytes (addresses). The symbol refers to the first address of the 2761allocated storage. 2762 2763@node Symbol Type 2764@subsection Type 2765 2766@cindex type of a symbol 2767@cindex symbol type 2768The type attribute of a symbol contains relocation (section) 2769information, any flag settings indicating that a symbol is external, and 2770(optionally), other information for linkers and debuggers. The exact 2771format depends on the object-code output format in use. 2772 2773@ifset aout-bout 2774@ifclear GENERIC 2775@ifset BOUT 2776@c The following avoids a "widow" subsection title. @group would be 2777@c better if it were available outside examples. 2778@need 1000 2779@node a.out Symbols 2780@subsection Symbol Attributes: @code{a.out}, @code{b.out} 2781 2782@cindex @code{b.out} symbol attributes 2783@cindex symbol attributes, @code{b.out} 2784These symbol attributes appear only when @code{@value{AS}} is configured for 2785one of the Berkeley-descended object output formats---@code{a.out} or 2786@code{b.out}. 2787 2788@end ifset 2789@ifclear BOUT 2790@node a.out Symbols 2791@subsection Symbol Attributes: @code{a.out} 2792 2793@cindex @code{a.out} symbol attributes 2794@cindex symbol attributes, @code{a.out} 2795 2796@end ifclear 2797@end ifclear 2798@ifset GENERIC 2799@node a.out Symbols 2800@subsection Symbol Attributes: @code{a.out} 2801 2802@cindex @code{a.out} symbol attributes 2803@cindex symbol attributes, @code{a.out} 2804 2805@end ifset 2806@menu 2807* Symbol Desc:: Descriptor 2808* Symbol Other:: Other 2809@end menu 2810 2811@node Symbol Desc 2812@subsubsection Descriptor 2813 2814@cindex descriptor, of @code{a.out} symbol 2815This is an arbitrary 16-bit value. You may establish a symbol's 2816descriptor value by using a @code{.desc} statement 2817(@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to 2818@code{@value{AS}}. 2819 2820@node Symbol Other 2821@subsubsection Other 2822 2823@cindex other attribute, of @code{a.out} symbol 2824This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}. 2825@end ifset 2826 2827@ifset COFF 2828@node COFF Symbols 2829@subsection Symbol Attributes for COFF 2830 2831@cindex COFF symbol attributes 2832@cindex symbol attributes, COFF 2833 2834The COFF format supports a multitude of auxiliary symbol attributes; 2835like the primary symbol attributes, they are set between @code{.def} and 2836@code{.endef} directives. 2837 2838@subsubsection Primary Attributes 2839 2840@cindex primary attributes, COFF symbols 2841The symbol name is set with @code{.def}; the value and type, 2842respectively, with @code{.val} and @code{.type}. 2843 2844@subsubsection Auxiliary Attributes 2845 2846@cindex auxiliary attributes, COFF symbols 2847The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, 2848@code{.size}, and @code{.tag} can generate auxiliary symbol table 2849information for COFF. 2850@end ifset 2851 2852@ifset SOM 2853@node SOM Symbols 2854@subsection Symbol Attributes for SOM 2855 2856@cindex SOM symbol attributes 2857@cindex symbol attributes, SOM 2858 2859The SOM format for the HPPA supports a multitude of symbol attributes set with 2860the @code{.EXPORT} and @code{.IMPORT} directives. 2861 2862The attributes are described in @cite{HP9000 Series 800 Assembly 2863Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and 2864@code{EXPORT} assembler directive documentation. 2865@end ifset 2866 2867@node Expressions 2868@chapter Expressions 2869 2870@cindex expressions 2871@cindex addresses 2872@cindex numeric values 2873An @dfn{expression} specifies an address or numeric value. 2874Whitespace may precede and/or follow an expression. 2875 2876The result of an expression must be an absolute number, or else an offset into 2877a particular section. If an expression is not absolute, and there is not 2878enough information when @code{@value{AS}} sees the expression to know its 2879section, a second pass over the source program might be necessary to interpret 2880the expression---but the second pass is currently not implemented. 2881@code{@value{AS}} aborts with an error message in this situation. 2882 2883@menu 2884* Empty Exprs:: Empty Expressions 2885* Integer Exprs:: Integer Expressions 2886@end menu 2887 2888@node Empty Exprs 2889@section Empty Expressions 2890 2891@cindex empty expressions 2892@cindex expressions, empty 2893An empty expression has no value: it is just whitespace or null. 2894Wherever an absolute expression is required, you may omit the 2895expression, and @code{@value{AS}} assumes a value of (absolute) 0. This 2896is compatible with other assemblers. 2897 2898@node Integer Exprs 2899@section Integer Expressions 2900 2901@cindex integer expressions 2902@cindex expressions, integer 2903An @dfn{integer expression} is one or more @emph{arguments} delimited 2904by @emph{operators}. 2905 2906@menu 2907* Arguments:: Arguments 2908* Operators:: Operators 2909* Prefix Ops:: Prefix Operators 2910* Infix Ops:: Infix Operators 2911@end menu 2912 2913@node Arguments 2914@subsection Arguments 2915 2916@cindex expression arguments 2917@cindex arguments in expressions 2918@cindex operands in expressions 2919@cindex arithmetic operands 2920@dfn{Arguments} are symbols, numbers or subexpressions. In other 2921contexts arguments are sometimes called ``arithmetic operands''. In 2922this manual, to avoid confusing them with the ``instruction operands'' of 2923the machine language, we use the term ``argument'' to refer to parts of 2924expressions only, reserving the word ``operand'' to refer only to machine 2925instruction operands. 2926 2927Symbols are evaluated to yield @{@var{section} @var{NNN}@} where 2928@var{section} is one of text, data, bss, absolute, 2929or undefined. @var{NNN} is a signed, 2's complement 32 bit 2930integer. 2931 2932Numbers are usually integers. 2933 2934A number can be a flonum or bignum. In this case, you are warned 2935that only the low order 32 bits are used, and @code{@value{AS}} pretends 2936these 32 bits are an integer. You may write integer-manipulating 2937instructions that act on exotic constants, compatible with other 2938assemblers. 2939 2940@cindex subexpressions 2941Subexpressions are a left parenthesis @samp{(} followed by an integer 2942expression, followed by a right parenthesis @samp{)}; or a prefix 2943operator followed by an argument. 2944 2945@node Operators 2946@subsection Operators 2947 2948@cindex operators, in expressions 2949@cindex arithmetic functions 2950@cindex functions, in expressions 2951@dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix 2952operators are followed by an argument. Infix operators appear 2953between their arguments. Operators may be preceded and/or followed by 2954whitespace. 2955 2956@node Prefix Ops 2957@subsection Prefix Operator 2958 2959@cindex prefix operators 2960@code{@value{AS}} has the following @dfn{prefix operators}. They each take 2961one argument, which must be absolute. 2962 2963@c the tex/end tex stuff surrounding this small table is meant to make 2964@c it align, on the printed page, with the similar table in the next 2965@c section (which is inside an enumerate). 2966@tex 2967\global\advance\leftskip by \itemindent 2968@end tex 2969 2970@table @code 2971@item - 2972@dfn{Negation}. Two's complement negation. 2973@item ~ 2974@dfn{Complementation}. Bitwise not. 2975@end table 2976 2977@tex 2978\global\advance\leftskip by -\itemindent 2979@end tex 2980 2981@node Infix Ops 2982@subsection Infix Operators 2983 2984@cindex infix operators 2985@cindex operators, permitted arguments 2986@dfn{Infix operators} take two arguments, one on either side. Operators 2987have precedence, but operations with equal precedence are performed left 2988to right. Apart from @code{+} or @code{-}, both arguments must be 2989absolute, and the result is absolute. 2990 2991@enumerate 2992@cindex operator precedence 2993@cindex precedence of operators 2994 2995@item 2996Highest Precedence 2997 2998@table @code 2999@item * 3000@dfn{Multiplication}. 3001 3002@item / 3003@dfn{Division}. Truncation is the same as the C operator @samp{/} 3004 3005@item % 3006@dfn{Remainder}. 3007 3008@item < 3009@itemx << 3010@dfn{Shift Left}. Same as the C operator @samp{<<}. 3011 3012@item > 3013@itemx >> 3014@dfn{Shift Right}. Same as the C operator @samp{>>}. 3015@end table 3016 3017@item 3018Intermediate precedence 3019 3020@table @code 3021@item | 3022 3023@dfn{Bitwise Inclusive Or}. 3024 3025@item & 3026@dfn{Bitwise And}. 3027 3028@item ^ 3029@dfn{Bitwise Exclusive Or}. 3030 3031@item ! 3032@dfn{Bitwise Or Not}. 3033@end table 3034 3035@item 3036Lowest Precedence 3037 3038@table @code 3039@cindex addition, permitted arguments 3040@cindex plus, permitted arguments 3041@cindex arguments for addition 3042@item + 3043@dfn{Addition}. If either argument is absolute, the result has the section of 3044the other argument. You may not add together arguments from different 3045sections. 3046 3047@cindex subtraction, permitted arguments 3048@cindex minus, permitted arguments 3049@cindex arguments for subtraction 3050@item - 3051@dfn{Subtraction}. If the right argument is absolute, the 3052result has the section of the left argument. 3053If both arguments are in the same section, the result is absolute. 3054You may not subtract arguments from different sections. 3055@c FIXME is there still something useful to say about undefined - undefined ? 3056@end table 3057@end enumerate 3058 3059In short, it's only meaningful to add or subtract the @emph{offsets} in an 3060address; you can only have a defined section in one of the two arguments. 3061 3062@node Pseudo Ops 3063@chapter Assembler Directives 3064 3065@cindex directives, machine independent 3066@cindex pseudo-ops, machine independent 3067@cindex machine independent directives 3068All assembler directives have names that begin with a period (@samp{.}). 3069The rest of the name is letters, usually in lower case. 3070 3071This chapter discusses directives that are available regardless of the 3072target machine configuration for the @sc{gnu} assembler. 3073@ifset GENERIC 3074Some machine configurations provide additional directives. 3075@xref{Machine Dependencies}. 3076@end ifset 3077@ifclear GENERIC 3078@ifset machine-directives 3079@xref{Machine Dependencies} for additional directives. 3080@end ifset 3081@end ifclear 3082 3083@menu 3084* Abort:: @code{.abort} 3085@ifset COFF 3086* ABORT:: @code{.ABORT} 3087@end ifset 3088 3089* Align:: @code{.align @var{abs-expr} , @var{abs-expr}} 3090* Ascii:: @code{.ascii "@var{string}"}@dots{} 3091* Asciz:: @code{.asciz "@var{string}"}@dots{} 3092* Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} 3093* Byte:: @code{.byte @var{expressions}} 3094* Comm:: @code{.comm @var{symbol} , @var{length} } 3095* Data:: @code{.data @var{subsection}} 3096@ifset COFF 3097* Def:: @code{.def @var{name}} 3098@end ifset 3099@ifset aout-bout 3100* Desc:: @code{.desc @var{symbol}, @var{abs-expression}} 3101@end ifset 3102@ifset COFF 3103* Dim:: @code{.dim} 3104@end ifset 3105 3106* Double:: @code{.double @var{flonums}} 3107* Eject:: @code{.eject} 3108* Else:: @code{.else} 3109* Elseif:: @code{.elseif} 3110* End:: @code{.end} 3111@ifset COFF 3112* Endef:: @code{.endef} 3113@end ifset 3114 3115* Endfunc:: @code{.endfunc} 3116* Endif:: @code{.endif} 3117* Equ:: @code{.equ @var{symbol}, @var{expression}} 3118* Equiv:: @code{.equiv @var{symbol}, @var{expression}} 3119* Err:: @code{.err} 3120* Exitm:: @code{.exitm} 3121* Extern:: @code{.extern} 3122* Fail:: @code{.fail} 3123@ifclear no-file-dir 3124* File:: @code{.file @var{string}} 3125@end ifclear 3126 3127* Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} 3128* Float:: @code{.float @var{flonums}} 3129* Func:: @code{.func} 3130* Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} 3131* hword:: @code{.hword @var{expressions}} 3132* Ident:: @code{.ident} 3133* If:: @code{.if @var{absolute expression}} 3134* Include:: @code{.include "@var{file}"} 3135* Int:: @code{.int @var{expressions}} 3136* Irp:: @code{.irp @var{symbol},@var{values}}@dots{} 3137* Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} 3138* Lcomm:: @code{.lcomm @var{symbol} , @var{length}} 3139* Lflags:: @code{.lflags} 3140@ifclear no-line-dir 3141* Line:: @code{.line @var{line-number}} 3142@end ifclear 3143 3144* Ln:: @code{.ln @var{line-number}} 3145* Linkonce:: @code{.linkonce [@var{type}]} 3146* List:: @code{.list} 3147* Long:: @code{.long @var{expressions}} 3148@ignore 3149* Lsym:: @code{.lsym @var{symbol}, @var{expression}} 3150@end ignore 3151 3152* Macro:: @code{.macro @var{name} @var{args}}@dots{} 3153* MRI:: @code{.mri @var{val}} 3154 3155* Nolist:: @code{.nolist} 3156* Octa:: @code{.octa @var{bignums}} 3157* Org:: @code{.org @var{new-lc} , @var{fill}} 3158* P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}} 3159* Print:: @code{.print @var{string}} 3160* Psize:: @code{.psize @var{lines}, @var{columns}} 3161* Purgem:: @code{.purgem @var{name}} 3162* Quad:: @code{.quad @var{bignums}} 3163* Rept:: @code{.rept @var{count}} 3164* Sbttl:: @code{.sbttl "@var{subheading}"} 3165@ifset COFF 3166* Scl:: @code{.scl @var{class}} 3167* Section:: @code{.section @var{name}, @var{subsection}} 3168@end ifset 3169 3170* Set:: @code{.set @var{symbol}, @var{expression}} 3171* Short:: @code{.short @var{expressions}} 3172* Single:: @code{.single @var{flonums}} 3173@ifset COFF 3174* Size:: @code{.size} 3175@end ifset 3176 3177* Skip:: @code{.skip @var{size} , @var{fill}} 3178* Sleb128:: @code{.sleb128 @var{expressions}} 3179* Space:: @code{.space @var{size} , @var{fill}} 3180@ifset have-stabs 3181* Stab:: @code{.stabd, .stabn, .stabs} 3182@end ifset 3183 3184* String:: @code{.string "@var{str}"} 3185* Struct:: @code{.struct @var{expression}} 3186@ifset ELF 3187* Symver:: @code{.symver @var{name},@var{name2@@nodename}} 3188@end ifset 3189@ifset COFF 3190* Tag:: @code{.tag @var{structname}} 3191@end ifset 3192 3193* Text:: @code{.text @var{subsection}} 3194* Title:: @code{.title "@var{heading}"} 3195@ifset COFF 3196* Type:: @code{.type @var{int}} 3197* Val:: @code{.val @var{addr}} 3198@end ifset 3199@ifset ELF 3200* Visibility:: @code{.internal @var{name}, .hidden @var{name}, .protected @var{name}} 3201@end ifset 3202 3203* Uleb128:: @code{.uleb128 @var{expressions}} 3204* Word:: @code{.word @var{expressions}} 3205* Deprecated:: Deprecated Directives 3206@end menu 3207 3208@node Abort 3209@section @code{.abort} 3210 3211@cindex @code{abort} directive 3212@cindex stopping the assembly 3213This directive stops the assembly immediately. It is for 3214compatibility with other assemblers. The original idea was that the 3215assembly language source would be piped into the assembler. If the sender 3216of the source quit, it could use this directive tells @code{@value{AS}} to 3217quit also. One day @code{.abort} will not be supported. 3218 3219@ifset COFF 3220@node ABORT 3221@section @code{.ABORT} 3222 3223@cindex @code{ABORT} directive 3224When producing COFF output, @code{@value{AS}} accepts this directive as a 3225synonym for @samp{.abort}. 3226 3227@ifset BOUT 3228When producing @code{b.out} output, @code{@value{AS}} accepts this directive, 3229but ignores it. 3230@end ifset 3231@end ifset 3232 3233@node Align 3234@section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 3235 3236@cindex padding the location counter 3237@cindex @code{align} directive 3238Pad the location counter (in the current subsection) to a particular storage 3239boundary. The first expression (which must be absolute) is the alignment 3240required, as described below. 3241 3242The second expression (also absolute) gives the fill value to be stored in the 3243padding bytes. It (and the comma) may be omitted. If it is omitted, the 3244padding bytes are normally zero. However, on some systems, if the section is 3245marked as containing code and the fill value is omitted, the space is filled 3246with no-op instructions. 3247 3248The third expression is also absolute, and is also optional. If it is present, 3249it is the maximum number of bytes that should be skipped by this alignment 3250directive. If doing the alignment would require skipping more bytes than the 3251specified maximum, then the alignment is not done at all. You can omit the 3252fill value (the second argument) entirely by simply using two commas after the 3253required alignment; this can be useful if you want the alignment to be filled 3254with no-op instructions when appropriate. 3255 3256The way the required alignment is specified varies from system to system. 3257For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF 3258format, 3259the first expression is the 3260alignment request in bytes. For example @samp{.align 8} advances 3261the location counter until it is a multiple of 8. If the location counter 3262is already a multiple of 8, no change is needed. 3263 3264For other systems, including the i386 using a.out format, and the arm and 3265strongarm, it is the 3266number of low-order zero bits the location counter must have after 3267advancement. For example @samp{.align 3} advances the location 3268counter until it a multiple of 8. If the location counter is already a 3269multiple of 8, no change is needed. 3270 3271This inconsistency is due to the different behaviors of the various 3272native assemblers for these systems which GAS must emulate. 3273GAS also provides @code{.balign} and @code{.p2align} directives, 3274described later, which have a consistent behavior across all 3275architectures (but are specific to GAS). 3276 3277@node Ascii 3278@section @code{.ascii "@var{string}"}@dots{} 3279 3280@cindex @code{ascii} directive 3281@cindex string literals 3282@code{.ascii} expects zero or more string literals (@pxref{Strings}) 3283separated by commas. It assembles each string (with no automatic 3284trailing zero byte) into consecutive addresses. 3285 3286@node Asciz 3287@section @code{.asciz "@var{string}"}@dots{} 3288 3289@cindex @code{asciz} directive 3290@cindex zero-terminated strings 3291@cindex null-terminated strings 3292@code{.asciz} is just like @code{.ascii}, but each string is followed by 3293a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. 3294 3295@node Balign 3296@section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 3297 3298@cindex padding the location counter given number of bytes 3299@cindex @code{balign} directive 3300Pad the location counter (in the current subsection) to a particular 3301storage boundary. The first expression (which must be absolute) is the 3302alignment request in bytes. For example @samp{.balign 8} advances 3303the location counter until it is a multiple of 8. If the location counter 3304is already a multiple of 8, no change is needed. 3305 3306The second expression (also absolute) gives the fill value to be stored in the 3307padding bytes. It (and the comma) may be omitted. If it is omitted, the 3308padding bytes are normally zero. However, on some systems, if the section is 3309marked as containing code and the fill value is omitted, the space is filled 3310with no-op instructions. 3311 3312The third expression is also absolute, and is also optional. If it is present, 3313it is the maximum number of bytes that should be skipped by this alignment 3314directive. If doing the alignment would require skipping more bytes than the 3315specified maximum, then the alignment is not done at all. You can omit the 3316fill value (the second argument) entirely by simply using two commas after the 3317required alignment; this can be useful if you want the alignment to be filled 3318with no-op instructions when appropriate. 3319 3320@cindex @code{balignw} directive 3321@cindex @code{balignl} directive 3322The @code{.balignw} and @code{.balignl} directives are variants of the 3323@code{.balign} directive. The @code{.balignw} directive treats the fill 3324pattern as a two byte word value. The @code{.balignl} directives treats the 3325fill pattern as a four byte longword value. For example, @code{.balignw 33264,0x368d} will align to a multiple of 4. If it skips two bytes, they will be 3327filled in with the value 0x368d (the exact placement of the bytes depends upon 3328the endianness of the processor). If it skips 1 or 3 bytes, the fill value is 3329undefined. 3330 3331@node Byte 3332@section @code{.byte @var{expressions}} 3333 3334@cindex @code{byte} directive 3335@cindex integers, one byte 3336@code{.byte} expects zero or more expressions, separated by commas. 3337Each expression is assembled into the next byte. 3338 3339@node Comm 3340@section @code{.comm @var{symbol} , @var{length} } 3341 3342@cindex @code{comm} directive 3343@cindex symbol, common 3344@code{.comm} declares a common symbol named @var{symbol}. When linking, a 3345common symbol in one object file may be merged with a defined or common symbol 3346of the same name in another object file. If @code{@value{LD}} does not see a 3347definition for the symbol--just one or more common symbols--then it will 3348allocate @var{length} bytes of uninitialized memory. @var{length} must be an 3349absolute expression. If @code{@value{LD}} sees multiple common symbols with 3350the same name, and they do not all have the same size, it will allocate space 3351using the largest size. 3352 3353@ifset ELF 3354When using ELF, the @code{.comm} directive takes an optional third argument. 3355This is the desired alignment of the symbol, specified as a byte boundary (for 3356example, an alignment of 16 means that the least significant 4 bits of the 3357address should be zero). The alignment must be an absolute expression, and it 3358must be a power of two. If @code{@value{LD}} allocates uninitialized memory 3359for the common symbol, it will use the alignment when placing the symbol. If 3360no alignment is specified, @code{@value{AS}} will set the alignment to the 3361largest power of two less than or equal to the size of the symbol, up to a 3362maximum of 16. 3363@end ifset 3364 3365@ifset HPPA 3366The syntax for @code{.comm} differs slightly on the HPPA. The syntax is 3367@samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. 3368@end ifset 3369 3370@node Data 3371@section @code{.data @var{subsection}} 3372 3373@cindex @code{data} directive 3374@code{.data} tells @code{@value{AS}} to assemble the following statements onto the 3375end of the data subsection numbered @var{subsection} (which is an 3376absolute expression). If @var{subsection} is omitted, it defaults 3377to zero. 3378 3379@ifset COFF 3380@node Def 3381@section @code{.def @var{name}} 3382 3383@cindex @code{def} directive 3384@cindex COFF symbols, debugging 3385@cindex debugging COFF symbols 3386Begin defining debugging information for a symbol @var{name}; the 3387definition extends until the @code{.endef} directive is encountered. 3388@ifset BOUT 3389 3390This directive is only observed when @code{@value{AS}} is configured for COFF 3391format output; when producing @code{b.out}, @samp{.def} is recognized, 3392but ignored. 3393@end ifset 3394@end ifset 3395 3396@ifset aout-bout 3397@node Desc 3398@section @code{.desc @var{symbol}, @var{abs-expression}} 3399 3400@cindex @code{desc} directive 3401@cindex COFF symbol descriptor 3402@cindex symbol descriptor, COFF 3403This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) 3404to the low 16 bits of an absolute expression. 3405 3406@ifset COFF 3407The @samp{.desc} directive is not available when @code{@value{AS}} is 3408configured for COFF output; it is only for @code{a.out} or @code{b.out} 3409object format. For the sake of compatibility, @code{@value{AS}} accepts 3410it, but produces no output, when configured for COFF. 3411@end ifset 3412@end ifset 3413 3414@ifset COFF 3415@node Dim 3416@section @code{.dim} 3417 3418@cindex @code{dim} directive 3419@cindex COFF auxiliary symbol information 3420@cindex auxiliary symbol information, COFF 3421This directive is generated by compilers to include auxiliary debugging 3422information in the symbol table. It is only permitted inside 3423@code{.def}/@code{.endef} pairs. 3424@ifset BOUT 3425 3426@samp{.dim} is only meaningful when generating COFF format output; when 3427@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 3428ignores it. 3429@end ifset 3430@end ifset 3431 3432@node Double 3433@section @code{.double @var{flonums}} 3434 3435@cindex @code{double} directive 3436@cindex floating point numbers (double) 3437@code{.double} expects zero or more flonums, separated by commas. It 3438assembles floating point numbers. 3439@ifset GENERIC 3440The exact kind of floating point numbers emitted depends on how 3441@code{@value{AS}} is configured. @xref{Machine Dependencies}. 3442@end ifset 3443@ifclear GENERIC 3444@ifset IEEEFLOAT 3445On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers 3446in @sc{ieee} format. 3447@end ifset 3448@end ifclear 3449 3450@node Eject 3451@section @code{.eject} 3452 3453@cindex @code{eject} directive 3454@cindex new page, in listings 3455@cindex page, in listings 3456@cindex listing control: new page 3457Force a page break at this point, when generating assembly listings. 3458 3459@node Else 3460@section @code{.else} 3461 3462@cindex @code{else} directive 3463@code{.else} is part of the @code{@value{AS}} support for conditional 3464assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section 3465of code to be assembled if the condition for the preceding @code{.if} 3466was false. 3467 3468@node Elseif 3469@section @code{.elseif} 3470 3471@cindex @code{elseif} directive 3472@code{.elseif} is part of the @code{@value{AS}} support for conditional 3473assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new 3474@code{.if} block that would otherwise fill the entire @code{.else} section. 3475 3476@node End 3477@section @code{.end} 3478 3479@cindex @code{end} directive 3480@code{.end} marks the end of the assembly file. @code{@value{AS}} does not 3481process anything in the file past the @code{.end} directive. 3482 3483@ifset COFF 3484@node Endef 3485@section @code{.endef} 3486 3487@cindex @code{endef} directive 3488This directive flags the end of a symbol definition begun with 3489@code{.def}. 3490@ifset BOUT 3491 3492@samp{.endef} is only meaningful when generating COFF format output; if 3493@code{@value{AS}} is configured to generate @code{b.out}, it accepts this 3494directive but ignores it. 3495@end ifset 3496@end ifset 3497 3498@node Endfunc 3499@section @code{.endfunc} 3500@cindex @code{endfunc} directive 3501@code{.endfunc} marks the end of a function specified with @code{.func}. 3502 3503@node Endif 3504@section @code{.endif} 3505 3506@cindex @code{endif} directive 3507@code{.endif} is part of the @code{@value{AS}} support for conditional assembly; 3508it marks the end of a block of code that is only assembled 3509conditionally. @xref{If,,@code{.if}}. 3510 3511@node Equ 3512@section @code{.equ @var{symbol}, @var{expression}} 3513 3514@cindex @code{equ} directive 3515@cindex assigning values to symbols 3516@cindex symbols, assigning values to 3517This directive sets the value of @var{symbol} to @var{expression}. 3518It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}. 3519 3520@ifset HPPA 3521The syntax for @code{equ} on the HPPA is 3522@samp{@var{symbol} .equ @var{expression}}. 3523@end ifset 3524 3525@node Equiv 3526@section @code{.equiv @var{symbol}, @var{expression}} 3527@cindex @code{equiv} directive 3528The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that 3529the assembler will signal an error if @var{symbol} is already defined. 3530 3531Except for the contents of the error message, this is roughly equivalent to 3532@smallexample 3533.ifdef SYM 3534.err 3535.endif 3536.equ SYM,VAL 3537@end smallexample 3538 3539@node Err 3540@section @code{.err} 3541@cindex @code{err} directive 3542If @code{@value{AS}} assembles a @code{.err} directive, it will print an error 3543message and, unless the @code{-Z} option was used, it will not generate an 3544object file. This can be used to signal error an conditionally compiled code. 3545 3546@node Exitm 3547@section @code{.exitm} 3548Exit early from the current macro definition. @xref{Macro}. 3549 3550@node Extern 3551@section @code{.extern} 3552 3553@cindex @code{extern} directive 3554@code{.extern} is accepted in the source program---for compatibility 3555with other assemblers---but it is ignored. @code{@value{AS}} treats 3556all undefined symbols as external. 3557 3558@node Fail 3559@section @code{.fail @var{expression}} 3560 3561@cindex @code{fail} directive 3562Generates an error or a warning. If the value of the @var{expression} is 500 3563or more, @code{@value{AS}} will print a warning message. If the value is less 3564than 500, @code{@value{AS}} will print an error message. The message will 3565include the value of @var{expression}. This can occasionally be useful inside 3566complex nested macros or conditional assembly. 3567 3568@ifclear no-file-dir 3569@node File 3570@section @code{.file @var{string}} 3571 3572@cindex @code{file} directive 3573@cindex logical file name 3574@cindex file name, logical 3575@code{.file} tells @code{@value{AS}} that we are about to start a new logical 3576file. @var{string} is the new file name. In general, the filename is 3577recognized whether or not it is surrounded by quotes @samp{"}; but if you wish 3578to specify an empty file name, you must give the quotes--@code{""}. This 3579statement may go away in future: it is only recognized to be compatible with 3580old @code{@value{AS}} programs. 3581@ifset A29K 3582In some configurations of @code{@value{AS}}, @code{.file} has already been 3583removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}. 3584@end ifset 3585@end ifclear 3586 3587@node Fill 3588@section @code{.fill @var{repeat} , @var{size} , @var{value}} 3589 3590@cindex @code{fill} directive 3591@cindex writing patterns in memory 3592@cindex patterns, writing in memory 3593@var{result}, @var{size} and @var{value} are absolute expressions. 3594This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} 3595may be zero or more. @var{Size} may be zero or more, but if it is 3596more than 8, then it is deemed to have the value 8, compatible with 3597other people's assemblers. The contents of each @var{repeat} bytes 3598is taken from an 8-byte number. The highest order 4 bytes are 3599zero. The lowest order 4 bytes are @var{value} rendered in the 3600byte-order of an integer on the computer @code{@value{AS}} is assembling for. 3601Each @var{size} bytes in a repetition is taken from the lowest order 3602@var{size} bytes of this number. Again, this bizarre behavior is 3603compatible with other people's assemblers. 3604 3605@var{size} and @var{value} are optional. 3606If the second comma and @var{value} are absent, @var{value} is 3607assumed zero. If the first comma and following tokens are absent, 3608@var{size} is assumed to be 1. 3609 3610@node Float 3611@section @code{.float @var{flonums}} 3612 3613@cindex floating point numbers (single) 3614@cindex @code{float} directive 3615This directive assembles zero or more flonums, separated by commas. It 3616has the same effect as @code{.single}. 3617@ifset GENERIC 3618The exact kind of floating point numbers emitted depends on how 3619@code{@value{AS}} is configured. 3620@xref{Machine Dependencies}. 3621@end ifset 3622@ifclear GENERIC 3623@ifset IEEEFLOAT 3624On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers 3625in @sc{ieee} format. 3626@end ifset 3627@end ifclear 3628 3629@node Func 3630@section @code{.func @var{name}[,@var{label}]} 3631@cindex @code{func} directive 3632@code{.func} emits debugging information to denote function @var{name}, and 3633is ignored unless the file is assembled with debugging enabled. 3634Only @samp{--gstabs} is currently supported. 3635@var{label} is the entry point of the function and if omitted @var{name} 3636prepended with the @samp{leading char} is used. 3637@samp{leading char} is usually @code{_} or nothing, depending on the target. 3638All functions are currently defined to have @code{void} return type. 3639The function must be terminated with @code{.endfunc}. 3640 3641@node Global 3642@section @code{.global @var{symbol}}, @code{.globl @var{symbol}} 3643 3644@cindex @code{global} directive 3645@cindex symbol, making visible to linker 3646@code{.global} makes the symbol visible to @code{@value{LD}}. If you define 3647@var{symbol} in your partial program, its value is made available to 3648other partial programs that are linked with it. Otherwise, 3649@var{symbol} takes its attributes from a symbol of the same name 3650from another file linked into the same program. 3651 3652Both spellings (@samp{.globl} and @samp{.global}) are accepted, for 3653compatibility with other assemblers. 3654 3655@ifset HPPA 3656On the HPPA, @code{.global} is not always enough to make it accessible to other 3657partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. 3658@xref{HPPA Directives,, HPPA Assembler Directives}. 3659@end ifset 3660 3661@node hword 3662@section @code{.hword @var{expressions}} 3663 3664@cindex @code{hword} directive 3665@cindex integers, 16-bit 3666@cindex numbers, 16-bit 3667@cindex sixteen bit integers 3668This expects zero or more @var{expressions}, and emits 3669a 16 bit number for each. 3670 3671@ifset GENERIC 3672This directive is a synonym for @samp{.short}; depending on the target 3673architecture, it may also be a synonym for @samp{.word}. 3674@end ifset 3675@ifclear GENERIC 3676@ifset W32 3677This directive is a synonym for @samp{.short}. 3678@end ifset 3679@ifset W16 3680This directive is a synonym for both @samp{.short} and @samp{.word}. 3681@end ifset 3682@end ifclear 3683 3684@node Ident 3685@section @code{.ident} 3686 3687@cindex @code{ident} directive 3688This directive is used by some assemblers to place tags in object files. 3689@code{@value{AS}} simply accepts the directive for source-file 3690compatibility with such assemblers, but does not actually emit anything 3691for it. 3692 3693@node If 3694@section @code{.if @var{absolute expression}} 3695 3696@cindex conditional assembly 3697@cindex @code{if} directive 3698@code{.if} marks the beginning of a section of code which is only 3699considered part of the source program being assembled if the argument 3700(which must be an @var{absolute expression}) is non-zero. The end of 3701the conditional section of code must be marked by @code{.endif} 3702(@pxref{Endif,,@code{.endif}}); optionally, you may include code for the 3703alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). 3704If you have several conditions to check, @code{.elseif} may be used to avoid 3705nesting blocks if/else within each subsequent @code{.else} block. 3706 3707The following variants of @code{.if} are also supported: 3708@table @code 3709@cindex @code{ifdef} directive 3710@item .ifdef @var{symbol} 3711Assembles the following section of code if the specified @var{symbol} 3712has been defined. 3713 3714@cindex @code{ifc} directive 3715@item .ifc @var{string1},@var{string2} 3716Assembles the following section of code if the two strings are the same. The 3717strings may be optionally quoted with single quotes. If they are not quoted, 3718the first string stops at the first comma, and the second string stops at the 3719end of the line. Strings which contain whitespace should be quoted. The 3720string comparison is case sensitive. 3721 3722@cindex @code{ifeq} directive 3723@item .ifeq @var{absolute expression} 3724Assembles the following section of code if the argument is zero. 3725 3726@cindex @code{ifeqs} directive 3727@item .ifeqs @var{string1},@var{string2} 3728Another form of @code{.ifc}. The strings must be quoted using double quotes. 3729 3730@cindex @code{ifge} directive 3731@item .ifge @var{absolute expression} 3732Assembles the following section of code if the argument is greater than or 3733equal to zero. 3734 3735@cindex @code{ifgt} directive 3736@item .ifgt @var{absolute expression} 3737Assembles the following section of code if the argument is greater than zero. 3738 3739@cindex @code{ifle} directive 3740@item .ifle @var{absolute expression} 3741Assembles the following section of code if the argument is less than or equal 3742to zero. 3743 3744@cindex @code{iflt} directive 3745@item .iflt @var{absolute expression} 3746Assembles the following section of code if the argument is less than zero. 3747 3748@cindex @code{ifnc} directive 3749@item .ifnc @var{string1},@var{string2}. 3750Like @code{.ifc}, but the sense of the test is reversed: this assembles the 3751following section of code if the two strings are not the same. 3752 3753@cindex @code{ifndef} directive 3754@cindex @code{ifnotdef} directive 3755@item .ifndef @var{symbol} 3756@itemx .ifnotdef @var{symbol} 3757Assembles the following section of code if the specified @var{symbol} 3758has not been defined. Both spelling variants are equivalent. 3759 3760@cindex @code{ifne} directive 3761@item .ifne @var{absolute expression} 3762Assembles the following section of code if the argument is not equal to zero 3763(in other words, this is equivalent to @code{.if}). 3764 3765@cindex @code{ifnes} directive 3766@item .ifnes @var{string1},@var{string2} 3767Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the 3768following section of code if the two strings are not the same. 3769@end table 3770 3771@node Include 3772@section @code{.include "@var{file}"} 3773 3774@cindex @code{include} directive 3775@cindex supporting files, including 3776@cindex files, including 3777This directive provides a way to include supporting files at specified 3778points in your source program. The code from @var{file} is assembled as 3779if it followed the point of the @code{.include}; when the end of the 3780included file is reached, assembly of the original file continues. You 3781can control the search paths used with the @samp{-I} command-line option 3782(@pxref{Invoking,,Command-Line Options}). Quotation marks are required 3783around @var{file}. 3784 3785@node Int 3786@section @code{.int @var{expressions}} 3787 3788@cindex @code{int} directive 3789@cindex integers, 32-bit 3790Expect zero or more @var{expressions}, of any section, separated by commas. 3791For each expression, emit a number that, at run time, is the value of that 3792expression. The byte order and bit size of the number depends on what kind 3793of target the assembly is for. 3794 3795@ifclear GENERIC 3796@ifset H8 3797On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit 3798integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits 379932-bit integers. 3800@end ifset 3801@end ifclear 3802 3803@node Irp 3804@section @code{.irp @var{symbol},@var{values}}@dots{} 3805 3806@cindex @code{irp} directive 3807Evaluate a sequence of statements assigning different values to @var{symbol}. 3808The sequence of statements starts at the @code{.irp} directive, and is 3809terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is 3810set to @var{value}, and the sequence of statements is assembled. If no 3811@var{value} is listed, the sequence of statements is assembled once, with 3812@var{symbol} set to the null string. To refer to @var{symbol} within the 3813sequence of statements, use @var{\symbol}. 3814 3815For example, assembling 3816 3817@example 3818 .irp param,1,2,3 3819 move d\param,sp@@- 3820 .endr 3821@end example 3822 3823is equivalent to assembling 3824 3825@example 3826 move d1,sp@@- 3827 move d2,sp@@- 3828 move d3,sp@@- 3829@end example 3830 3831@node Irpc 3832@section @code{.irpc @var{symbol},@var{values}}@dots{} 3833 3834@cindex @code{irpc} directive 3835Evaluate a sequence of statements assigning different values to @var{symbol}. 3836The sequence of statements starts at the @code{.irpc} directive, and is 3837terminated by an @code{.endr} directive. For each character in @var{value}, 3838@var{symbol} is set to the character, and the sequence of statements is 3839assembled. If no @var{value} is listed, the sequence of statements is 3840assembled once, with @var{symbol} set to the null string. To refer to 3841@var{symbol} within the sequence of statements, use @var{\symbol}. 3842 3843For example, assembling 3844 3845@example 3846 .irpc param,123 3847 move d\param,sp@@- 3848 .endr 3849@end example 3850 3851is equivalent to assembling 3852 3853@example 3854 move d1,sp@@- 3855 move d2,sp@@- 3856 move d3,sp@@- 3857@end example 3858 3859@node Lcomm 3860@section @code{.lcomm @var{symbol} , @var{length}} 3861 3862@cindex @code{lcomm} directive 3863@cindex local common symbols 3864@cindex symbols, local common 3865Reserve @var{length} (an absolute expression) bytes for a local common 3866denoted by @var{symbol}. The section and value of @var{symbol} are 3867those of the new local common. The addresses are allocated in the bss 3868section, so that at run-time the bytes start off zeroed. @var{Symbol} 3869is not declared global (@pxref{Global,,@code{.global}}), so is normally 3870not visible to @code{@value{LD}}. 3871 3872@ifset GENERIC 3873Some targets permit a third argument to be used with @code{.lcomm}. This 3874argument specifies the desired alignment of the symbol in the bss section. 3875@end ifset 3876 3877@ifset HPPA 3878The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is 3879@samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. 3880@end ifset 3881 3882@node Lflags 3883@section @code{.lflags} 3884 3885@cindex @code{lflags} directive (ignored) 3886@code{@value{AS}} accepts this directive, for compatibility with other 3887assemblers, but ignores it. 3888 3889@ifclear no-line-dir 3890@node Line 3891@section @code{.line @var{line-number}} 3892 3893@cindex @code{line} directive 3894@end ifclear 3895@ifset no-line-dir 3896@node Ln 3897@section @code{.ln @var{line-number}} 3898 3899@cindex @code{ln} directive 3900@end ifset 3901@cindex logical line number 3902@ifset aout-bout 3903Change the logical line number. @var{line-number} must be an absolute 3904expression. The next line has that logical line number. Therefore any other 3905statements on the current line (after a statement separator character) are 3906reported as on logical line number @var{line-number} @minus{} 1. One day 3907@code{@value{AS}} will no longer support this directive: it is recognized only 3908for compatibility with existing assembler programs. 3909 3910@ifset GENERIC 3911@ifset A29K 3912@emph{Warning:} In the AMD29K configuration of @value{AS}, this command is 3913not available; use the synonym @code{.ln} in that context. 3914@end ifset 3915@end ifset 3916@end ifset 3917 3918@ifclear no-line-dir 3919Even though this is a directive associated with the @code{a.out} or 3920@code{b.out} object-code formats, @code{@value{AS}} still recognizes it 3921when producing COFF output, and treats @samp{.line} as though it 3922were the COFF @samp{.ln} @emph{if} it is found outside a 3923@code{.def}/@code{.endef} pair. 3924 3925Inside a @code{.def}, @samp{.line} is, instead, one of the directives 3926used by compilers to generate auxiliary symbol information for 3927debugging. 3928@end ifclear 3929 3930@node Linkonce 3931@section @code{.linkonce [@var{type}]} 3932@cindex COMDAT 3933@cindex @code{linkonce} directive 3934@cindex common sections 3935Mark the current section so that the linker only includes a single copy of it. 3936This may be used to include the same section in several different object files, 3937but ensure that the linker will only include it once in the final output file. 3938The @code{.linkonce} pseudo-op must be used for each instance of the section. 3939Duplicate sections are detected based on the section name, so it should be 3940unique. 3941 3942This directive is only supported by a few object file formats; as of this 3943writing, the only object file format which supports it is the Portable 3944Executable format used on Windows NT. 3945 3946The @var{type} argument is optional. If specified, it must be one of the 3947following strings. For example: 3948@smallexample 3949.linkonce same_size 3950@end smallexample 3951Not all types may be supported on all object file formats. 3952 3953@table @code 3954@item discard 3955Silently discard duplicate sections. This is the default. 3956 3957@item one_only 3958Warn if there are duplicate sections, but still keep only one copy. 3959 3960@item same_size 3961Warn if any of the duplicates have different sizes. 3962 3963@item same_contents 3964Warn if any of the duplicates do not have exactly the same contents. 3965@end table 3966 3967@node Ln 3968@section @code{.ln @var{line-number}} 3969 3970@cindex @code{ln} directive 3971@ifclear no-line-dir 3972@samp{.ln} is a synonym for @samp{.line}. 3973@end ifclear 3974@ifset no-line-dir 3975Tell @code{@value{AS}} to change the logical line number. @var{line-number} 3976must be an absolute expression. The next line has that logical 3977line number, so any other statements on the current line (after a 3978statement separator character @code{;}) are reported as on logical 3979line number @var{line-number} @minus{} 1. 3980@ifset BOUT 3981 3982This directive is accepted, but ignored, when @code{@value{AS}} is 3983configured for @code{b.out}; its effect is only associated with COFF 3984output format. 3985@end ifset 3986@end ifset 3987 3988@node MRI 3989@section @code{.mri @var{val}} 3990 3991@cindex @code{mri} directive 3992@cindex MRI mode, temporarily 3993If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If 3994@var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change 3995affects code assembled until the next @code{.mri} directive, or until the end 3996of the file. @xref{M, MRI mode, MRI mode}. 3997 3998@node List 3999@section @code{.list} 4000 4001@cindex @code{list} directive 4002@cindex listing control, turning on 4003Control (in conjunction with the @code{.nolist} directive) whether or 4004not assembly listings are generated. These two directives maintain an 4005internal counter (which is zero initially). @code{.list} increments the 4006counter, and @code{.nolist} decrements it. Assembly listings are 4007generated whenever the counter is greater than zero. 4008 4009By default, listings are disabled. When you enable them (with the 4010@samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), 4011the initial value of the listing counter is one. 4012 4013@node Long 4014@section @code{.long @var{expressions}} 4015 4016@cindex @code{long} directive 4017@code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}. 4018 4019@ignore 4020@c no one seems to know what this is for or whether this description is 4021@c what it really ought to do 4022@node Lsym 4023@section @code{.lsym @var{symbol}, @var{expression}} 4024 4025@cindex @code{lsym} directive 4026@cindex symbol, not referenced in assembly 4027@code{.lsym} creates a new symbol named @var{symbol}, but does not put it in 4028the hash table, ensuring it cannot be referenced by name during the 4029rest of the assembly. This sets the attributes of the symbol to be 4030the same as the expression value: 4031@smallexample 4032@var{other} = @var{descriptor} = 0 4033@var{type} = @r{(section of @var{expression})} 4034@var{value} = @var{expression} 4035@end smallexample 4036@noindent 4037The new symbol is not flagged as external. 4038@end ignore 4039 4040@node Macro 4041@section @code{.macro} 4042 4043@cindex macros 4044The commands @code{.macro} and @code{.endm} allow you to define macros that 4045generate assembly output. For example, this definition specifies a macro 4046@code{sum} that puts a sequence of numbers into memory: 4047 4048@example 4049 .macro sum from=0, to=5 4050 .long \from 4051 .if \to-\from 4052 sum "(\from+1)",\to 4053 .endif 4054 .endm 4055@end example 4056 4057@noindent 4058With that definition, @samp{SUM 0,5} is equivalent to this assembly input: 4059 4060@example 4061 .long 0 4062 .long 1 4063 .long 2 4064 .long 3 4065 .long 4 4066 .long 5 4067@end example 4068 4069@ftable @code 4070@item .macro @var{macname} 4071@itemx .macro @var{macname} @var{macargs} @dots{} 4072@cindex @code{macro} directive 4073Begin the definition of a macro called @var{macname}. If your macro 4074definition requires arguments, specify their names after the macro name, 4075separated by commas or spaces. You can supply a default value for any 4076macro argument by following the name with @samp{=@var{deflt}}. For 4077example, these are all valid @code{.macro} statements: 4078 4079@table @code 4080@item .macro comm 4081Begin the definition of a macro called @code{comm}, which takes no 4082arguments. 4083 4084@item .macro plus1 p, p1 4085@itemx .macro plus1 p p1 4086Either statement begins the definition of a macro called @code{plus1}, 4087which takes two arguments; within the macro definition, write 4088@samp{\p} or @samp{\p1} to evaluate the arguments. 4089 4090@item .macro reserve_str p1=0 p2 4091Begin the definition of a macro called @code{reserve_str}, with two 4092arguments. The first argument has a default value, but not the second. 4093After the definition is complete, you can call the macro either as 4094@samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to 4095@var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str 4096,@var{b}} (with @samp{\p1} evaluating as the default, in this case 4097@samp{0}, and @samp{\p2} evaluating to @var{b}). 4098@end table 4099 4100When you call a macro, you can specify the argument values either by 4101position, or by keyword. For example, @samp{sum 9,17} is equivalent to 4102@samp{sum to=17, from=9}. 4103 4104@item .endm 4105@cindex @code{endm} directive 4106Mark the end of a macro definition. 4107 4108@item .exitm 4109@cindex @code{exitm} directive 4110Exit early from the current macro definition. 4111 4112@cindex number of macros executed 4113@cindex macros, count executed 4114@item \@@ 4115@code{@value{AS}} maintains a counter of how many macros it has 4116executed in this pseudo-variable; you can copy that number to your 4117output with @samp{\@@}, but @emph{only within a macro definition}. 4118 4119@ignore 4120@item LOCAL @var{name} [ , @dots{} ] 4121@emph{Warning: @code{LOCAL} is only available if you select ``alternate 4122macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,, 4123Alternate macro syntax}. 4124 4125Generate a string replacement for each of the @var{name} arguments, and 4126replace any instances of @var{name} in each macro expansion. The 4127replacement string is unique in the assembly, and different for each 4128separate macro expansion. @code{LOCAL} allows you to write macros that 4129define symbols, without fear of conflict between separate macro expansions. 4130@end ignore 4131@end ftable 4132 4133@node Nolist 4134@section @code{.nolist} 4135 4136@cindex @code{nolist} directive 4137@cindex listing control, turning off 4138Control (in conjunction with the @code{.list} directive) whether or 4139not assembly listings are generated. These two directives maintain an 4140internal counter (which is zero initially). @code{.list} increments the 4141counter, and @code{.nolist} decrements it. Assembly listings are 4142generated whenever the counter is greater than zero. 4143 4144@node Octa 4145@section @code{.octa @var{bignums}} 4146 4147@c FIXME: double size emitted for "octa" on i960, others? Or warn? 4148@cindex @code{octa} directive 4149@cindex integer, 16-byte 4150@cindex sixteen byte integer 4151This directive expects zero or more bignums, separated by commas. For each 4152bignum, it emits a 16-byte integer. 4153 4154The term ``octa'' comes from contexts in which a ``word'' is two bytes; 4155hence @emph{octa}-word for 16 bytes. 4156 4157@node Org 4158@section @code{.org @var{new-lc} , @var{fill}} 4159 4160@cindex @code{org} directive 4161@cindex location counter, advancing 4162@cindex advancing location counter 4163@cindex current address, advancing 4164Advance the location counter of the current section to 4165@var{new-lc}. @var{new-lc} is either an absolute expression or an 4166expression with the same section as the current subsection. That is, 4167you can't use @code{.org} to cross sections: if @var{new-lc} has the 4168wrong section, the @code{.org} directive is ignored. To be compatible 4169with former assemblers, if the section of @var{new-lc} is absolute, 4170@code{@value{AS}} issues a warning, then pretends the section of @var{new-lc} 4171is the same as the current subsection. 4172 4173@code{.org} may only increase the location counter, or leave it 4174unchanged; you cannot use @code{.org} to move the location counter 4175backwards. 4176 4177@c double negative used below "not undefined" because this is a specific 4178@c reference to "undefined" (as SEG_UNKNOWN is called in this manual) 4179@c section. doc@cygnus.com 18feb91 4180Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc} 4181may not be undefined. If you really detest this restriction we eagerly await 4182a chance to share your improved assembler. 4183 4184Beware that the origin is relative to the start of the section, not 4185to the start of the subsection. This is compatible with other 4186people's assemblers. 4187 4188When the location counter (of the current subsection) is advanced, the 4189intervening bytes are filled with @var{fill} which should be an 4190absolute expression. If the comma and @var{fill} are omitted, 4191@var{fill} defaults to zero. 4192 4193@node P2align 4194@section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 4195 4196@cindex padding the location counter given a power of two 4197@cindex @code{p2align} directive 4198Pad the location counter (in the current subsection) to a particular 4199storage boundary. The first expression (which must be absolute) is the 4200number of low-order zero bits the location counter must have after 4201advancement. For example @samp{.p2align 3} advances the location 4202counter until it a multiple of 8. If the location counter is already a 4203multiple of 8, no change is needed. 4204 4205The second expression (also absolute) gives the fill value to be stored in the 4206padding bytes. It (and the comma) may be omitted. If it is omitted, the 4207padding bytes are normally zero. However, on some systems, if the section is 4208marked as containing code and the fill value is omitted, the space is filled 4209with no-op instructions. 4210 4211The third expression is also absolute, and is also optional. If it is present, 4212it is the maximum number of bytes that should be skipped by this alignment 4213directive. If doing the alignment would require skipping more bytes than the 4214specified maximum, then the alignment is not done at all. You can omit the 4215fill value (the second argument) entirely by simply using two commas after the 4216required alignment; this can be useful if you want the alignment to be filled 4217with no-op instructions when appropriate. 4218 4219@cindex @code{p2alignw} directive 4220@cindex @code{p2alignl} directive 4221The @code{.p2alignw} and @code{.p2alignl} directives are variants of the 4222@code{.p2align} directive. The @code{.p2alignw} directive treats the fill 4223pattern as a two byte word value. The @code{.p2alignl} directives treats the 4224fill pattern as a four byte longword value. For example, @code{.p2alignw 42252,0x368d} will align to a multiple of 4. If it skips two bytes, they will be 4226filled in with the value 0x368d (the exact placement of the bytes depends upon 4227the endianness of the processor). If it skips 1 or 3 bytes, the fill value is 4228undefined. 4229 4230@node Print 4231@section @code{.print @var{string}} 4232 4233@cindex @code{print} directive 4234@code{@value{AS}} will print @var{string} on the standard output during 4235assembly. You must put @var{string} in double quotes. 4236 4237@node Psize 4238@section @code{.psize @var{lines} , @var{columns}} 4239 4240@cindex @code{psize} directive 4241@cindex listing control: paper size 4242@cindex paper size, for listings 4243Use this directive to declare the number of lines---and, optionally, the 4244number of columns---to use for each page, when generating listings. 4245 4246If you do not use @code{.psize}, listings use a default line-count 4247of 60. You may omit the comma and @var{columns} specification; the 4248default width is 200 columns. 4249 4250@code{@value{AS}} generates formfeeds whenever the specified number of 4251lines is exceeded (or whenever you explicitly request one, using 4252@code{.eject}). 4253 4254If you specify @var{lines} as @code{0}, no formfeeds are generated save 4255those explicitly specified with @code{.eject}. 4256 4257@node Purgem 4258@section @code{.purgem @var{name}} 4259 4260@cindex @code{purgem} directive 4261Undefine the macro @var{name}, so that later uses of the string will not be 4262expanded. @xref{Macro}. 4263 4264@node Quad 4265@section @code{.quad @var{bignums}} 4266 4267@cindex @code{quad} directive 4268@code{.quad} expects zero or more bignums, separated by commas. For 4269each bignum, it emits 4270@ifclear bignum-16 4271an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a 4272warning message; and just takes the lowest order 8 bytes of the bignum. 4273@cindex eight-byte integer 4274@cindex integer, 8-byte 4275 4276The term ``quad'' comes from contexts in which a ``word'' is two bytes; 4277hence @emph{quad}-word for 8 bytes. 4278@end ifclear 4279@ifset bignum-16 4280a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a 4281warning message; and just takes the lowest order 16 bytes of the bignum. 4282@cindex sixteen-byte integer 4283@cindex integer, 16-byte 4284@end ifset 4285 4286@node Rept 4287@section @code{.rept @var{count}} 4288 4289@cindex @code{rept} directive 4290Repeat the sequence of lines between the @code{.rept} directive and the next 4291@code{.endr} directive @var{count} times. 4292 4293For example, assembling 4294 4295@example 4296 .rept 3 4297 .long 0 4298 .endr 4299@end example 4300 4301is equivalent to assembling 4302 4303@example 4304 .long 0 4305 .long 0 4306 .long 0 4307@end example 4308 4309@node Sbttl 4310@section @code{.sbttl "@var{subheading}"} 4311 4312@cindex @code{sbttl} directive 4313@cindex subtitles for listings 4314@cindex listing control: subtitle 4315Use @var{subheading} as the title (third line, immediately after the 4316title line) when generating assembly listings. 4317 4318This directive affects subsequent pages, as well as the current page if 4319it appears within ten lines of the top of a page. 4320 4321@ifset COFF 4322@node Scl 4323@section @code{.scl @var{class}} 4324 4325@cindex @code{scl} directive 4326@cindex symbol storage class (COFF) 4327@cindex COFF symbol storage class 4328Set the storage-class value for a symbol. This directive may only be 4329used inside a @code{.def}/@code{.endef} pair. Storage class may flag 4330whether a symbol is static or external, or it may record further 4331symbolic debugging information. 4332@ifset BOUT 4333 4334The @samp{.scl} directive is primarily associated with COFF output; when 4335configured to generate @code{b.out} output format, @code{@value{AS}} 4336accepts this directive but ignores it. 4337@end ifset 4338@end ifset 4339 4340@node Section 4341@section @code{.section @var{name}} 4342 4343@cindex @code{section} directive 4344@cindex named section 4345Use the @code{.section} directive to assemble the following code into a section 4346named @var{name}. 4347 4348This directive is only supported for targets that actually support arbitrarily 4349named sections; on @code{a.out} targets, for example, it is not accepted, even 4350with a standard @code{a.out} section name. 4351 4352@ifset COFF 4353For COFF targets, the @code{.section} directive is used in one of the following 4354ways: 4355@smallexample 4356.section @var{name}[, "@var{flags}"] 4357.section @var{name}[, @var{subsegment}] 4358@end smallexample 4359 4360If the optional argument is quoted, it is taken as flags to use for the 4361section. Each flag is a single character. The following flags are recognized: 4362@table @code 4363@item b 4364bss section (uninitialized data) 4365@item n 4366section is not loaded 4367@item w 4368writable section 4369@item d 4370data section 4371@item r 4372read-only section 4373@item x 4374executable section 4375@item s 4376shared section (meaningful for PE targets) 4377@end table 4378 4379If no flags are specified, the default flags depend upon the section name. If 4380the section name is not recognized, the default will be for the section to be 4381loaded and writable. 4382 4383If the optional argument to the @code{.section} directive is not quoted, it is 4384taken as a subsegment number (@pxref{Sub-Sections}). 4385@end ifset 4386 4387@ifset ELF 4388For ELF targets, the @code{.section} directive is used like this: 4389@smallexample 4390.section @var{name}[, "@var{flags}"[, @@@var{type}]] 4391@end smallexample 4392The optional @var{flags} argument is a quoted string which may contain any 4393combintion of the following characters: 4394@table @code 4395@item a 4396section is allocatable 4397@item w 4398section is writable 4399@item x 4400section is executable 4401@end table 4402 4403The optional @var{type} argument may contain one of the following constants: 4404@table @code 4405@item @@progbits 4406section contains data 4407@item @@nobits 4408section does not contain data (i.e., section only occupies space) 4409@end table 4410 4411If no flags are specified, the default flags depend upon the section name. If 4412the section name is not recognized, the default will be for the section to have 4413none of the above flags: it will not be allocated in memory, nor writable, nor 4414executable. The section will contain data. 4415 4416For ELF targets, the assembler supports another type of @code{.section} 4417directive for compatibility with the Solaris assembler: 4418@smallexample 4419.section "@var{name}"[, @var{flags}...] 4420@end smallexample 4421Note that the section name is quoted. There may be a sequence of comma 4422separated flags: 4423@table @code 4424@item #alloc 4425section is allocatable 4426@item #write 4427section is writable 4428@item #execinstr 4429section is executable 4430@end table 4431@end ifset 4432 4433@node Set 4434@section @code{.set @var{symbol}, @var{expression}} 4435 4436@cindex @code{set} directive 4437@cindex symbol value, setting 4438Set the value of @var{symbol} to @var{expression}. This 4439changes @var{symbol}'s value and type to conform to 4440@var{expression}. If @var{symbol} was flagged as external, it remains 4441flagged (@pxref{Symbol Attributes}). 4442 4443You may @code{.set} a symbol many times in the same assembly. 4444 4445If you @code{.set} a global symbol, the value stored in the object 4446file is the last value stored into it. 4447 4448@ifset HPPA 4449The syntax for @code{set} on the HPPA is 4450@samp{@var{symbol} .set @var{expression}}. 4451@end ifset 4452 4453@node Short 4454@section @code{.short @var{expressions}} 4455 4456@cindex @code{short} directive 4457@ifset GENERIC 4458@code{.short} is normally the same as @samp{.word}. 4459@xref{Word,,@code{.word}}. 4460 4461In some configurations, however, @code{.short} and @code{.word} generate 4462numbers of different lengths; @pxref{Machine Dependencies}. 4463@end ifset 4464@ifclear GENERIC 4465@ifset W16 4466@code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. 4467@end ifset 4468@ifset W32 4469This expects zero or more @var{expressions}, and emits 4470a 16 bit number for each. 4471@end ifset 4472@end ifclear 4473 4474@node Single 4475@section @code{.single @var{flonums}} 4476 4477@cindex @code{single} directive 4478@cindex floating point numbers (single) 4479This directive assembles zero or more flonums, separated by commas. It 4480has the same effect as @code{.float}. 4481@ifset GENERIC 4482The exact kind of floating point numbers emitted depends on how 4483@code{@value{AS}} is configured. @xref{Machine Dependencies}. 4484@end ifset 4485@ifclear GENERIC 4486@ifset IEEEFLOAT 4487On the @value{TARGET} family, @code{.single} emits 32-bit floating point 4488numbers in @sc{ieee} format. 4489@end ifset 4490@end ifclear 4491 4492@ifset COFF 4493@node Size 4494@section @code{.size} 4495 4496@cindex @code{size} directive 4497This directive is generated by compilers to include auxiliary debugging 4498information in the symbol table. It is only permitted inside 4499@code{.def}/@code{.endef} pairs. 4500@ifset BOUT 4501 4502@samp{.size} is only meaningful when generating COFF format output; when 4503@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 4504ignores it. 4505@end ifset 4506@end ifset 4507 4508@node Sleb128 4509@section @code{.sleb128 @var{expressions}} 4510 4511@cindex @code{sleb128} directive 4512@var{sleb128} stands for ``signed little endian base 128.'' This is a 4513compact, variable length representation of numbers used by the DWARF 4514symbolic debugging format. @xref{Uleb128,@code{.uleb128}}. 4515 4516@ifclear no-space-dir 4517@node Skip 4518@section @code{.skip @var{size} , @var{fill}} 4519 4520@cindex @code{skip} directive 4521@cindex filling memory 4522This directive emits @var{size} bytes, each of value @var{fill}. Both 4523@var{size} and @var{fill} are absolute expressions. If the comma and 4524@var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as 4525@samp{.space}. 4526 4527@node Space 4528@section @code{.space @var{size} , @var{fill}} 4529 4530@cindex @code{space} directive 4531@cindex filling memory 4532This directive emits @var{size} bytes, each of value @var{fill}. Both 4533@var{size} and @var{fill} are absolute expressions. If the comma 4534and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same 4535as @samp{.skip}. 4536 4537@ifset HPPA 4538@quotation 4539@emph{Warning:} @code{.space} has a completely different meaning for HPPA 4540targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 4541Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the 4542@code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, 4543for a summary. 4544@end quotation 4545@end ifset 4546@end ifclear 4547 4548@ifset A29K 4549@ifclear GENERIC 4550@node Space 4551@section @code{.space} 4552@cindex @code{space} directive 4553@end ifclear 4554On the AMD 29K, this directive is ignored; it is accepted for 4555compatibility with other AMD 29K assemblers. 4556 4557@quotation 4558@emph{Warning:} In most versions of the @sc{gnu} assembler, the directive 4559@code{.space} has the effect of @code{.block} @xref{Machine Dependencies}. 4560@end quotation 4561@end ifset 4562 4563@ifset have-stabs 4564@node Stab 4565@section @code{.stabd, .stabn, .stabs} 4566 4567@cindex symbolic debuggers, information for 4568@cindex @code{stab@var{x}} directives 4569There are three directives that begin @samp{.stab}. 4570All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. 4571The symbols are not entered in the @code{@value{AS}} hash table: they 4572cannot be referenced elsewhere in the source file. 4573Up to five fields are required: 4574 4575@table @var 4576@item string 4577This is the symbol's name. It may contain any character except 4578@samp{\000}, so is more general than ordinary symbol names. Some 4579debuggers used to code arbitrarily complex structures into symbol names 4580using this field. 4581 4582@item type 4583An absolute expression. The symbol's type is set to the low 8 bits of 4584this expression. Any bit pattern is permitted, but @code{@value{LD}} 4585and debuggers choke on silly bit patterns. 4586 4587@item other 4588An absolute expression. The symbol's ``other'' attribute is set to the 4589low 8 bits of this expression. 4590 4591@item desc 4592An absolute expression. The symbol's descriptor is set to the low 16 4593bits of this expression. 4594 4595@item value 4596An absolute expression which becomes the symbol's value. 4597@end table 4598 4599If a warning is detected while reading a @code{.stabd}, @code{.stabn}, 4600or @code{.stabs} statement, the symbol has probably already been created; 4601you get a half-formed symbol in your object file. This is 4602compatible with earlier assemblers! 4603 4604@table @code 4605@cindex @code{stabd} directive 4606@item .stabd @var{type} , @var{other} , @var{desc} 4607 4608The ``name'' of the symbol generated is not even an empty string. 4609It is a null pointer, for compatibility. Older assemblers used a 4610null pointer so they didn't waste space in object files with empty 4611strings. 4612 4613The symbol's value is set to the location counter, 4614relocatably. When your program is linked, the value of this symbol 4615is the address of the location counter when the @code{.stabd} was 4616assembled. 4617 4618@cindex @code{stabn} directive 4619@item .stabn @var{type} , @var{other} , @var{desc} , @var{value} 4620The name of the symbol is set to the empty string @code{""}. 4621 4622@cindex @code{stabs} directive 4623@item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} 4624All five fields are specified. 4625@end table 4626@end ifset 4627@c end have-stabs 4628 4629@node String 4630@section @code{.string} "@var{str}" 4631 4632@cindex string, copying to object file 4633@cindex @code{string} directive 4634 4635Copy the characters in @var{str} to the object file. You may specify more than 4636one string to copy, separated by commas. Unless otherwise specified for a 4637particular machine, the assembler marks the end of each string with a 0 byte. 4638You can use any of the escape sequences described in @ref{Strings,,Strings}. 4639 4640@node Struct 4641@section @code{.struct @var{expression}} 4642 4643@cindex @code{struct} directive 4644Switch to the absolute section, and set the section offset to @var{expression}, 4645which must be an absolute expression. You might use this as follows: 4646@smallexample 4647 .struct 0 4648field1: 4649 .struct field1 + 4 4650field2: 4651 .struct field2 + 4 4652field3: 4653@end smallexample 4654This would define the symbol @code{field1} to have the value 0, the symbol 4655@code{field2} to have the value 4, and the symbol @code{field3} to have the 4656value 8. Assembly would be left in the absolute section, and you would need to 4657use a @code{.section} directive of some sort to change to some other section 4658before further assembly. 4659 4660@ifset ELF 4661@node Symver 4662@section @code{.symver} 4663@cindex @code{symver} directive 4664@cindex symbol versioning 4665@cindex versions of symbols 4666Use the @code{.symver} directive to bind symbols to specific version nodes 4667within a source file. This is only supported on ELF platforms, and is 4668typically used when assembling files to be linked into a shared library. 4669There are cases where it may make sense to use this in objects to be bound 4670into an application itself so as to override a versioned symbol from a 4671shared library. 4672 4673For ELF targets, the @code{.symver} directive is used like this: 4674@smallexample 4675.symver @var{name}, @var{name2@@nodename} 4676@end smallexample 4677In this case, the symbol @var{name} must exist and be defined within the file 4678being assembled. The @code{.versym} directive effectively creates a symbol 4679alias with the name @var{name2@@nodename}, and in fact the main reason that we 4680just don't try and create a regular alias is that the @var{@@} character isn't 4681permitted in symbol names. The @var{name2} part of the name is the actual name 4682of the symbol by which it will be externally referenced. The name @var{name} 4683itself is merely a name of convenience that is used so that it is possible to 4684have definitions for multiple versions of a function within a single source 4685file, and so that the compiler can unambiguously know which version of a 4686function is being mentioned. The @var{nodename} portion of the alias should be 4687the name of a node specified in the version script supplied to the linker when 4688building a shared library. If you are attempting to override a versioned 4689symbol from a shared library, then @var{nodename} should correspond to the 4690nodename of the symbol you are trying to override. 4691@end ifset 4692 4693@ifset COFF 4694@node Tag 4695@section @code{.tag @var{structname}} 4696 4697@cindex COFF structure debugging 4698@cindex structure debugging, COFF 4699@cindex @code{tag} directive 4700This directive is generated by compilers to include auxiliary debugging 4701information in the symbol table. It is only permitted inside 4702@code{.def}/@code{.endef} pairs. Tags are used to link structure 4703definitions in the symbol table with instances of those structures. 4704@ifset BOUT 4705 4706@samp{.tag} is only used when generating COFF format output; when 4707@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 4708ignores it. 4709@end ifset 4710@end ifset 4711 4712@node Text 4713@section @code{.text @var{subsection}} 4714 4715@cindex @code{text} directive 4716Tells @code{@value{AS}} to assemble the following statements onto the end of 4717the text subsection numbered @var{subsection}, which is an absolute 4718expression. If @var{subsection} is omitted, subsection number zero 4719is used. 4720 4721@node Title 4722@section @code{.title "@var{heading}"} 4723 4724@cindex @code{title} directive 4725@cindex listing control: title line 4726Use @var{heading} as the title (second line, immediately after the 4727source file name and pagenumber) when generating assembly listings. 4728 4729This directive affects subsequent pages, as well as the current page if 4730it appears within ten lines of the top of a page. 4731 4732@ifset COFF 4733@node Type 4734@section @code{.type @var{int}} 4735 4736@cindex COFF symbol type 4737@cindex symbol type, COFF 4738@cindex @code{type} directive 4739This directive, permitted only within @code{.def}/@code{.endef} pairs, 4740records the integer @var{int} as the type attribute of a symbol table entry. 4741@ifset BOUT 4742 4743@samp{.type} is associated only with COFF format output; when 4744@code{@value{AS}} is configured for @code{b.out} output, it accepts this 4745directive but ignores it. 4746@end ifset 4747@end ifset 4748 4749@ifset COFF 4750@node Val 4751@section @code{.val @var{addr}} 4752 4753@cindex @code{val} directive 4754@cindex COFF value attribute 4755@cindex value attribute, COFF 4756This directive, permitted only within @code{.def}/@code{.endef} pairs, 4757records the address @var{addr} as the value attribute of a symbol table 4758entry. 4759@ifset BOUT 4760 4761@samp{.val} is used only for COFF output; when @code{@value{AS}} is 4762configured for @code{b.out}, it accepts this directive but ignores it. 4763@end ifset 4764@end ifset 4765 4766@node Uleb128 4767@section @code{.uleb128 @var{expressions}} 4768 4769@cindex @code{uleb128} directive 4770@var{uleb128} stands for ``unsigned little endian base 128.'' This is a 4771compact, variable length representation of numbers used by the DWARF 4772symbolic debugging format. @xref{Sleb128,@code{.sleb128}}. 4773 4774@ifset ELF 4775@node Visibility 4776@section @code{.internal}, @code{.hidden}, @code{.protected} 4777@cindex @code{internal} directive 4778@cindex @code{hidden} directive 4779@cindex @code{protected} directive 4780@cindex symbol visibility 4781 4782These directives can be used to set the visibility of a specified symbol. By 4783default a symbol's visibility is set by its binding (local, global or weak), 4784but these directives can be used to override that. 4785 4786A visibility of @code{protected} means that any references to the symbol from 4787within the component that defines the symbol must be resolved to the definition 4788in that component, even if a definition in another component would normally 4789preempt this. 4790 4791A visibility of @code{hidden} means that the symbol is not visible to other 4792components. Such a symbol is always considered to be protected as well. 4793 4794A visibility of @code{internal} is the same as a visibility of @code{hidden}, 4795except that some extra, processor specific processing must also be performed 4796upon the symbol. 4797 4798For ELF targets, the directives are used like this: 4799 4800@smallexample 4801.internal @var{name} 4802.hidden @var{name} 4803.protected @var{name} 4804@end smallexample 4805 4806@end ifset 4807 4808@node Word 4809@section @code{.word @var{expressions}} 4810 4811@cindex @code{word} directive 4812This directive expects zero or more @var{expressions}, of any section, 4813separated by commas. 4814@ifclear GENERIC 4815@ifset W32 4816For each expression, @code{@value{AS}} emits a 32-bit number. 4817@end ifset 4818@ifset W16 4819For each expression, @code{@value{AS}} emits a 16-bit number. 4820@end ifset 4821@end ifclear 4822@ifset GENERIC 4823 4824The size of the number emitted, and its byte order, 4825depend on what target computer the assembly is for. 4826@end ifset 4827 4828@c on amd29k, i960, sparc the "special treatment to support compilers" doesn't 4829@c happen---32-bit addressability, period; no long/short jumps. 4830@ifset DIFF-TBL-KLUGE 4831@cindex difference tables altered 4832@cindex altered difference tables 4833@quotation 4834@emph{Warning: Special Treatment to support Compilers} 4835@end quotation 4836 4837@ifset GENERIC 4838Machines with a 32-bit address space, but that do less than 32-bit 4839addressing, require the following special treatment. If the machine of 4840interest to you does 32-bit addressing (or doesn't require it; 4841@pxref{Machine Dependencies}), you can ignore this issue. 4842 4843@end ifset 4844In order to assemble compiler output into something that works, 4845@code{@value{AS}} occasionlly does strange things to @samp{.word} directives. 4846Directives of the form @samp{.word sym1-sym2} are often emitted by 4847compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a 4848directive of the form @samp{.word sym1-sym2}, and the difference between 4849@code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}} 4850creates a @dfn{secondary jump table}, immediately before the next label. 4851This secondary jump table is preceded by a short-jump to the 4852first byte after the secondary table. This short-jump prevents the flow 4853of control from accidentally falling into the new table. Inside the 4854table is a long-jump to @code{sym2}. The original @samp{.word} 4855contains @code{sym1} minus the address of the long-jump to 4856@code{sym2}. 4857 4858If there were several occurrences of @samp{.word sym1-sym2} before the 4859secondary jump table, all of them are adjusted. If there was a 4860@samp{.word sym3-sym4}, that also did not fit in sixteen bits, a 4861long-jump to @code{sym4} is included in the secondary jump table, 4862and the @code{.word} directives are adjusted to contain @code{sym3} 4863minus the address of the long-jump to @code{sym4}; and so on, for as many 4864entries in the original jump table as necessary. 4865 4866@ifset INTERNALS 4867@emph{This feature may be disabled by compiling @code{@value{AS}} with the 4868@samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse 4869assembly language programmers. 4870@end ifset 4871@end ifset 4872@c end DIFF-TBL-KLUGE 4873 4874@node Deprecated 4875@section Deprecated Directives 4876 4877@cindex deprecated directives 4878@cindex obsolescent directives 4879One day these directives won't work. 4880They are included for compatibility with older assemblers. 4881@table @t 4882@item .abort 4883@item .line 4884@end table 4885 4886@ifset GENERIC 4887@node Machine Dependencies 4888@chapter Machine Dependent Features 4889 4890@cindex machine dependencies 4891The machine instruction sets are (almost by definition) different on 4892each machine where @code{@value{AS}} runs. Floating point representations 4893vary as well, and @code{@value{AS}} often supports a few additional 4894directives or command-line options for compatibility with other 4895assemblers on a particular platform. Finally, some versions of 4896@code{@value{AS}} support special pseudo-instructions for branch 4897optimization. 4898 4899This chapter discusses most of these differences, though it does not 4900include details on any machine's instruction set. For details on that 4901subject, see the hardware manufacturer's manual. 4902 4903@menu 4904@ifset A29K 4905* AMD29K-Dependent:: AMD 29K Dependent Features 4906@end ifset 4907@ifset ARC 4908* ARC-Dependent:: ARC Dependent Features 4909@end ifset 4910@ifset ARM 4911* ARM-Dependent:: ARM Dependent Features 4912@end ifset 4913@ifset D10V 4914* D10V-Dependent:: D10V Dependent Features 4915@end ifset 4916@ifset D30V 4917* D30V-Dependent:: D30V Dependent Features 4918@end ifset 4919@ifset H8/300 4920* H8/300-Dependent:: Hitachi H8/300 Dependent Features 4921@end ifset 4922@ifset H8/500 4923* H8/500-Dependent:: Hitachi H8/500 Dependent Features 4924@end ifset 4925@ifset HPPA 4926* HPPA-Dependent:: HPPA Dependent Features 4927@end ifset 4928@ifset I370 4929* ESA/390-Dependent:: IBM ESA/390 Dependent Features 4930@end ifset 4931@ifset I80386 4932* i386-Dependent:: Intel 80386 Dependent Features 4933@end ifset 4934@ifset I960 4935* i960-Dependent:: Intel 80960 Dependent Features 4936@end ifset 4937@ifset M680X0 4938* M68K-Dependent:: M680x0 Dependent Features 4939@end ifset 4940@ifset MIPS 4941* MIPS-Dependent:: MIPS Dependent Features 4942@end ifset 4943@ifset SH 4944* SH-Dependent:: Hitachi SH Dependent Features 4945@end ifset 4946@ifset PJ 4947* PJ-Dependent:: picoJava Dependent Features 4948@end ifset 4949@ifset SPARC 4950* Sparc-Dependent:: SPARC Dependent Features 4951@end ifset 4952@ifset V850 4953* V850-Dependent:: V850 Dependent Features 4954@end ifset 4955@ifset Z8000 4956* Z8000-Dependent:: Z8000 Dependent Features 4957@end ifset 4958@ifset VAX 4959* Vax-Dependent:: VAX Dependent Features 4960@end ifset 4961@end menu 4962 4963@lowersections 4964@end ifset 4965 4966@c The following major nodes are *sections* in the GENERIC version, *chapters* 4967@c in single-cpu versions. This is mainly achieved by @lowersections. There is a 4968@c peculiarity: to preserve cross-references, there must be a node called 4969@c "Machine Dependencies". Hence the conditional nodenames in each 4970@c major node below. Node defaulting in makeinfo requires adjacency of 4971@c node and sectioning commands; hence the repetition of @chapter BLAH 4972@c in both conditional blocks. 4973 4974@ifset ARC 4975@ifset GENERIC 4976@page 4977@node ARC-Dependent 4978@chapter ARC Dependent Features 4979@end ifset 4980@ifclear GENERIC 4981@node Machine Dependencies 4982@chapter ARC Dependent Features 4983@end ifclear 4984 4985@cindex ARC support 4986@menu 4987* ARC-Opts:: Options 4988* ARC-Float:: Floating Point 4989* ARC-Directives:: Sparc Machine Directives 4990@end menu 4991 4992@node ARC-Opts 4993@section Options 4994 4995@cindex options for ARC 4996@cindex ARC options 4997@cindex architectures, ARC 4998@cindex ARC architectures 4999The ARC chip family includes several successive levels (or other 5000variants) of chip, using the same core instruction set, but including 5001a few additional instructions at each level. 5002 5003By default, @code{@value{AS}} assumes the core instruction set (ARC 5004base). The @code{.cpu} pseudo-op is intended to be used to select 5005the variant. 5006 5007@table @code 5008@cindex @code{-mbig-endian} option (ARC) 5009@cindex @code{-mlittle-endian} option (ARC) 5010@cindex ARC big-endian output 5011@cindex ARC little-endian output 5012@cindex big-endian output, ARC 5013@cindex little-endian output, ARC 5014@item -mbig-endian 5015@itemx -mlittle-endian 5016Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or 5017little-endian output at run time (unlike most other @sc{gnu} development 5018tools, which must be configured for one or the other). Use 5019@samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian} 5020for little-endian. 5021@end table 5022 5023@node ARC-Float 5024@section Floating Point 5025 5026@cindex floating point, ARC (@sc{ieee}) 5027@cindex ARC floating point (@sc{ieee}) 5028The ARC cpu family currently does not have hardware floating point 5029support. Software floating point support is provided by @code{GCC} 5030and uses @sc{ieee} floating-point numbers. 5031 5032@node ARC-Directives 5033@section ARC Machine Directives 5034 5035@cindex ARC machine directives 5036@cindex machine directives, ARC 5037The ARC version of @code{@value{AS}} supports the following additional 5038machine directives: 5039 5040@table @code 5041@item .cpu 5042@cindex @code{cpu} directive, SPARC 5043This must be followed by the desired cpu. 5044The ARC is intended to be customizable, @code{.cpu} is used to 5045select the desired variant [though currently there are none]. 5046 5047@end table 5048 5049@end ifset 5050 5051@ifset A29K 5052@include c-a29k.texi 5053@end ifset 5054 5055@ifset ARM 5056@include c-arm.texi 5057@end ifset 5058 5059@ifset Hitachi-all 5060@ifclear GENERIC 5061@node Machine Dependencies 5062@chapter Machine Dependent Features 5063 5064The machine instruction sets are different on each Hitachi chip family, 5065and there are also some syntax differences among the families. This 5066chapter describes the specific @code{@value{AS}} features for each 5067family. 5068 5069@menu 5070* H8/300-Dependent:: Hitachi H8/300 Dependent Features 5071* H8/500-Dependent:: Hitachi H8/500 Dependent Features 5072* SH-Dependent:: Hitachi SH Dependent Features 5073@end menu 5074@lowersections 5075@end ifclear 5076@end ifset 5077 5078@ifset D10V 5079@include c-d10v.texi 5080@end ifset 5081 5082@ifset D30V 5083@include c-d30v.texi 5084@end ifset 5085 5086@ifset H8/300 5087@include c-h8300.texi 5088@end ifset 5089 5090@ifset H8/500 5091@include c-h8500.texi 5092@end ifset 5093 5094@ifset HPPA 5095@include c-hppa.texi 5096@end ifset 5097 5098@ifset I370 5099@include c-i370.texi 5100@end ifset 5101 5102@ifset I80386 5103@include c-i386.texi 5104@end ifset 5105 5106@ifset I960 5107@include c-i960.texi 5108@end ifset 5109 5110 5111@ifset M680X0 5112@include c-m68k.texi 5113@end ifset 5114 5115@ifset MIPS 5116@include c-mips.texi 5117@end ifset 5118 5119@ifset NS32K 5120@include c-ns32k.texi 5121@end ifset 5122 5123@ifset PJ 5124@include c-pj.texi 5125@end ifset 5126 5127@ifset SH 5128@include c-sh.texi 5129@end ifset 5130 5131@ifset SPARC 5132@include c-sparc.texi 5133@end ifset 5134 5135@ifset Z8000 5136@include c-z8k.texi 5137@end ifset 5138 5139@ifset VAX 5140@include c-vax.texi 5141@end ifset 5142 5143@ifset V850 5144@include c-v850.texi 5145@end ifset 5146 5147@ifset GENERIC 5148@c reverse effect of @down at top of generic Machine-Dep chapter 5149@raisesections 5150@end ifset 5151 5152@node Reporting Bugs 5153@chapter Reporting Bugs 5154@cindex bugs in assembler 5155@cindex reporting bugs in assembler 5156 5157Your bug reports play an essential role in making @code{@value{AS}} reliable. 5158 5159Reporting a bug may help you by bringing a solution to your problem, or it may 5160not. But in any case the principal function of a bug report is to help the 5161entire community by making the next version of @code{@value{AS}} work better. 5162Bug reports are your contribution to the maintenance of @code{@value{AS}}. 5163 5164In order for a bug report to serve its purpose, you must include the 5165information that enables us to fix the bug. 5166 5167@menu 5168* Bug Criteria:: Have you found a bug? 5169* Bug Reporting:: How to report bugs 5170@end menu 5171 5172@node Bug Criteria 5173@section Have you found a bug? 5174@cindex bug criteria 5175 5176If you are not sure whether you have found a bug, here are some guidelines: 5177 5178@itemize @bullet 5179@cindex fatal signal 5180@cindex assembler crash 5181@cindex crash of assembler 5182@item 5183If the assembler gets a fatal signal, for any input whatever, that is a 5184@code{@value{AS}} bug. Reliable assemblers never crash. 5185 5186@cindex error on valid input 5187@item 5188If @code{@value{AS}} produces an error message for valid input, that is a bug. 5189 5190@cindex invalid input 5191@item 5192If @code{@value{AS}} does not produce an error message for invalid input, that 5193is a bug. However, you should note that your idea of ``invalid input'' might 5194be our idea of ``an extension'' or ``support for traditional practice''. 5195 5196@item 5197If you are an experienced user of assemblers, your suggestions for improvement 5198of @code{@value{AS}} are welcome in any case. 5199@end itemize 5200 5201@node Bug Reporting 5202@section How to report bugs 5203@cindex bug reports 5204@cindex assembler bugs, reporting 5205 5206A number of companies and individuals offer support for @sc{gnu} products. If 5207you obtained @code{@value{AS}} from a support organization, we recommend you 5208contact that organization first. 5209 5210You can find contact information for many support companies and 5211individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs 5212distribution. 5213 5214In any event, we also recommend that you send bug reports for @code{@value{AS}} 5215to @samp{bug-gnu-utils@@gnu.org}. 5216 5217The fundamental principle of reporting bugs usefully is this: 5218@strong{report all the facts}. If you are not sure whether to state a 5219fact or leave it out, state it! 5220 5221Often people omit facts because they think they know what causes the problem 5222and assume that some details do not matter. Thus, you might assume that the 5223name of a symbol you use in an example does not matter. Well, probably it does 5224not, but one cannot be sure. Perhaps the bug is a stray memory reference which 5225happens to fetch from the location where that name is stored in memory; 5226perhaps, if the name were different, the contents of that location would fool 5227the assembler into doing the right thing despite the bug. Play it safe and 5228give a specific, complete example. That is the easiest thing for you to do, 5229and the most helpful. 5230 5231Keep in mind that the purpose of a bug report is to enable us to fix the bug if 5232it is new to us. Therefore, always write your bug reports on the assumption 5233that the bug has not been reported previously. 5234 5235Sometimes people give a few sketchy facts and ask, ``Does this ring a 5236bell?'' Those bug reports are useless, and we urge everyone to 5237@emph{refuse to respond to them} except to chide the sender to report 5238bugs properly. 5239 5240To enable us to fix the bug, you should include all these things: 5241 5242@itemize @bullet 5243@item 5244The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start 5245it with the @samp{--version} argument. 5246 5247Without this, we will not know whether there is any point in looking for 5248the bug in the current version of @code{@value{AS}}. 5249 5250@item 5251Any patches you may have applied to the @code{@value{AS}} source. 5252 5253@item 5254The type of machine you are using, and the operating system name and 5255version number. 5256 5257@item 5258What compiler (and its version) was used to compile @code{@value{AS}}---e.g. 5259``@code{gcc-2.7}''. 5260 5261@item 5262The command arguments you gave the assembler to assemble your example and 5263observe the bug. To guarantee you will not omit something important, list them 5264all. A copy of the Makefile (or the output from make) is sufficient. 5265 5266If we were to try to guess the arguments, we would probably guess wrong 5267and then we might not encounter the bug. 5268 5269@item 5270A complete input file that will reproduce the bug. If the bug is observed when 5271the assembler is invoked via a compiler, send the assembler source, not the 5272high level language source. Most compilers will produce the assembler source 5273when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use 5274the options @samp{-v --save-temps}; this will save the assembler source in a 5275file with an extension of @file{.s}, and also show you exactly how 5276@code{@value{AS}} is being run. 5277 5278@item 5279A description of what behavior you observe that you believe is 5280incorrect. For example, ``It gets a fatal signal.'' 5281 5282Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we 5283will certainly notice it. But if the bug is incorrect output, we might not 5284notice unless it is glaringly wrong. You might as well not give us a chance to 5285make a mistake. 5286 5287Even if the problem you experience is a fatal signal, you should still say so 5288explicitly. Suppose something strange is going on, such as, your copy of 5289@code{@value{AS}} is out of synch, or you have encountered a bug in the C 5290library on your system. (This has happened!) Your copy might crash and ours 5291would not. If you told us to expect a crash, then when ours fails to crash, we 5292would know that the bug was not happening for us. If you had not told us to 5293expect a crash, then we would not be able to draw any conclusion from our 5294observations. 5295 5296@item 5297If you wish to suggest changes to the @code{@value{AS}} source, send us context 5298diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} 5299option. Always send diffs from the old file to the new file. If you even 5300discuss something in the @code{@value{AS}} source, refer to it by context, not 5301by line number. 5302 5303The line numbers in our development sources will not match those in your 5304sources. Your line numbers would convey no useful information to us. 5305@end itemize 5306 5307Here are some things that are not necessary: 5308 5309@itemize @bullet 5310@item 5311A description of the envelope of the bug. 5312 5313Often people who encounter a bug spend a lot of time investigating 5314which changes to the input file will make the bug go away and which 5315changes will not affect it. 5316 5317This is often time consuming and not very useful, because the way we 5318will find the bug is by running a single example under the debugger 5319with breakpoints, not by pure deduction from a series of examples. 5320We recommend that you save your time for something else. 5321 5322Of course, if you can find a simpler example to report @emph{instead} 5323of the original one, that is a convenience for us. Errors in the 5324output will be easier to spot, running under the debugger will take 5325less time, and so on. 5326 5327However, simplification is not vital; if you do not want to do this, 5328report the bug anyway and send us the entire test case you used. 5329 5330@item 5331A patch for the bug. 5332 5333A patch for the bug does help us if it is a good one. But do not omit 5334the necessary information, such as the test case, on the assumption that 5335a patch is all we need. We might see problems with your patch and decide 5336to fix the problem another way, or we might not understand it at all. 5337 5338Sometimes with a program as complicated as @code{@value{AS}} it is very hard to 5339construct an example that will make the program follow a certain path through 5340the code. If you do not send us the example, we will not be able to construct 5341one, so we will not be able to verify that the bug is fixed. 5342 5343And if we cannot understand what bug you are trying to fix, or why your 5344patch should be an improvement, we will not install it. A test case will 5345help us to understand. 5346 5347@item 5348A guess about what the bug is or what it depends on. 5349 5350Such guesses are usually wrong. Even we cannot guess right about such 5351things without first using the debugger to find the facts. 5352@end itemize 5353 5354@node Acknowledgements 5355@chapter Acknowledgements 5356 5357If you have contributed to @code{@value{AS}} and your name isn't listed here, 5358it is not meant as a slight. We just don't know about it. Send mail to the 5359maintainer, and we'll correct the situation. Currently 5360@c (January 1994), 5361the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). 5362 5363Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any 5364more details?} 5365 5366Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug 5367information and the 68k series machines, most of the preprocessing pass, and 5368extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. 5369 5370K. Richard Pixley maintained GAS for a while, adding various enhancements and 5371many bug fixes, including merging support for several processors, breaking GAS 5372up to handle multiple object file format back ends (including heavy rewrite, 5373testing, an integration of the coff and b.out back ends), adding configuration 5374including heavy testing and verification of cross assemblers and file splits 5375and renaming, converted GAS to strictly ANSI C including full prototypes, added 5376support for m680[34]0 and cpu32, did considerable work on i960 including a COFF 5377port (including considerable amounts of reverse engineering), a SPARC opcode 5378file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' 5379assertions and made them work, much other reorganization, cleanup, and lint. 5380 5381Ken Raeburn wrote the high-level BFD interface code to replace most of the code 5382in format-specific I/O modules. 5383 5384The original VMS support was contributed by David L. Kashtan. Eric Youngdale 5385has done much work with it since. 5386 5387The Intel 80386 machine description was written by Eliot Dresselhaus. 5388 5389Minh Tran-Le at IntelliCorp contributed some AIX 386 support. 5390 5391The Motorola 88k machine description was contributed by Devon Bowen of Buffalo 5392University and Torbjorn Granlund of the Swedish Institute of Computer Science. 5393 5394Keith Knowles at the Open Software Foundation wrote the original MIPS back end 5395(@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support 5396(which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to 5397support a.out format. 5398 5399Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k, 5400tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by 5401Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to 5402use BFD for some low-level operations, for use with the H8/300 and AMD 29k 5403targets. 5404 5405John Gilmore built the AMD 29000 support, added @code{.include} support, and 5406simplified the configuration of which versions accept which directives. He 5407updated the 68k machine description so that Motorola's opcodes always produced 5408fixed-size instructions (e.g. @code{jsr}), while synthetic instructions 5409remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested 5410cross-compilation support, and one bug in relaxation that took a week and 5411required the proverbial one-bit fix. 5412 5413Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the 541468k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), 5415added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and 5416PowerPC assembler, and made a few other minor patches. 5417 5418Steve Chamberlain made @code{@value{AS}} able to generate listings. 5419 5420Hewlett-Packard contributed support for the HP9000/300. 5421 5422Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) 5423along with a fairly extensive HPPA testsuite (for both SOM and ELF object 5424formats). This work was supported by both the Center for Software Science at 5425the University of Utah and Cygnus Support. 5426 5427Support for ELF format files has been worked on by Mark Eichin of Cygnus 5428Support (original, incomplete implementation for SPARC), Pete Hoogenboom and 5429Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open 5430Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, 5431and some initial 64-bit support). 5432 5433Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture. 5434 5435Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD 5436support for openVMS/Alpha. 5437 5438Several engineers at Cygnus Support have also provided many small bug fixes and 5439configuration enhancements. 5440 5441Many others have contributed large or small bugfixes and enhancements. If 5442you have contributed significant work and are not mentioned on this list, and 5443want to be, let us know. Some of the history has been lost; we are not 5444intentionally leaving anyone out. 5445 5446@node Index 5447@unnumbered Index 5448 5449@printindex cp 5450 5451@contents 5452@bye 5453@c Local Variables: 5454@c fill-column: 79 5455@c End: 5456