as.texinfo revision 60484
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, 1998 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, 1998 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@ifset ARM 1166@samp{;} for the ARM family; 1167@end ifset 1168 1169@node M 1170@section Assemble in MRI Compatibility Mode: @code{-M} 1171 1172@kindex -M 1173@cindex MRI compatibility mode 1174The @code{-M} or @code{--mri} option selects MRI compatibility mode. This 1175changes the syntax and pseudo-op handling of @code{@value{AS}} to make it 1176compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the 1177configured target) assembler from Microtec Research. The exact nature of the 1178MRI syntax will not be documented here; see the MRI manuals for more 1179information. Note in particular that the handling of macros and macro 1180arguments is somewhat different. The purpose of this option is to permit 1181assembling existing MRI assembler code using @code{@value{AS}}. 1182 1183The MRI compatibility is not complete. Certain operations of the MRI assembler 1184depend upon its object file format, and can not be supported using other object 1185file formats. Supporting these would require enhancing each object file format 1186individually. These are: 1187 1188@itemize @bullet 1189@item global symbols in common section 1190 1191The m68k MRI assembler supports common sections which are merged by the linker. 1192Other object file formats do not support this. @code{@value{AS}} handles 1193common sections by treating them as a single common symbol. It permits local 1194symbols to be defined within a common section, but it can not support global 1195symbols, since it has no way to describe them. 1196 1197@item complex relocations 1198 1199The MRI assemblers support relocations against a negated section address, and 1200relocations which combine the start addresses of two or more sections. These 1201are not support by other object file formats. 1202 1203@item @code{END} pseudo-op specifying start address 1204 1205The MRI @code{END} pseudo-op permits the specification of a start address. 1206This is not supported by other object file formats. The start address may 1207instead be specified using the @code{-e} option to the linker, or in a linker 1208script. 1209 1210@item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops 1211 1212The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module 1213name to the output file. This is not supported by other object file formats. 1214 1215@item @code{ORG} pseudo-op 1216 1217The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given 1218address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op, 1219which changes the location within the current section. Absolute sections are 1220not supported by other object file formats. The address of a section may be 1221assigned within a linker script. 1222@end itemize 1223 1224There are some other features of the MRI assembler which are not supported by 1225@code{@value{AS}}, typically either because they are difficult or because they 1226seem of little consequence. Some of these may be supported in future releases. 1227 1228@itemize @bullet 1229 1230@item EBCDIC strings 1231 1232EBCDIC strings are not supported. 1233 1234@item packed binary coded decimal 1235 1236Packed binary coded decimal is not supported. This means that the @code{DC.P} 1237and @code{DCB.P} pseudo-ops are not supported. 1238 1239@item @code{FEQU} pseudo-op 1240 1241The m68k @code{FEQU} pseudo-op is not supported. 1242 1243@item @code{NOOBJ} pseudo-op 1244 1245The m68k @code{NOOBJ} pseudo-op is not supported. 1246 1247@item @code{OPT} branch control options 1248 1249The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, 1250@code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically 1251relaxes all branches, whether forward or backward, to an appropriate size, so 1252these options serve no purpose. 1253 1254@item @code{OPT} list control options 1255 1256The following m68k @code{OPT} list control options are ignored: @code{C}, 1257@code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, 1258@code{MEX}, @code{MC}, @code{MD}, @code{X}. 1259 1260@item other @code{OPT} options 1261 1262The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, 1263@code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. 1264 1265@item @code{OPT} @code{D} option is default 1266 1267The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. 1268@code{OPT NOD} may be used to turn it off. 1269 1270@item @code{XREF} pseudo-op. 1271 1272The m68k @code{XREF} pseudo-op is ignored. 1273 1274@item @code{.debug} pseudo-op 1275 1276The i960 @code{.debug} pseudo-op is not supported. 1277 1278@item @code{.extended} pseudo-op 1279 1280The i960 @code{.extended} pseudo-op is not supported. 1281 1282@item @code{.list} pseudo-op. 1283 1284The various options of the i960 @code{.list} pseudo-op are not supported. 1285 1286@item @code{.optimize} pseudo-op 1287 1288The i960 @code{.optimize} pseudo-op is not supported. 1289 1290@item @code{.output} pseudo-op 1291 1292The i960 @code{.output} pseudo-op is not supported. 1293 1294@item @code{.setreal} pseudo-op 1295 1296The i960 @code{.setreal} pseudo-op is not supported. 1297 1298@end itemize 1299 1300@node MD 1301@section Dependency tracking: @code{--MD} 1302 1303@kindex --MD 1304@cindex dependency tracking 1305@cindex make rules 1306 1307@code{@value{AS}} can generate a dependency file for the file it creates. This 1308file consists of a single rule suitable for @code{make} describing the 1309dependencies of the main source file. 1310 1311The rule is written to the file named in its argument. 1312 1313This feature is used in the automatic updating of makefiles. 1314 1315@node o 1316@section Name the Object File: @code{-o} 1317 1318@kindex -o 1319@cindex naming object file 1320@cindex object file name 1321There is always one object file output when you run @code{@value{AS}}. By 1322default it has the name 1323@ifset GENERIC 1324@ifset I960 1325@file{a.out} (or @file{b.out}, for Intel 960 targets only). 1326@end ifset 1327@ifclear I960 1328@file{a.out}. 1329@end ifclear 1330@end ifset 1331@ifclear GENERIC 1332@ifset I960 1333@file{b.out}. 1334@end ifset 1335@ifclear I960 1336@file{a.out}. 1337@end ifclear 1338@end ifclear 1339You use this option (which takes exactly one filename) to give the 1340object file a different name. 1341 1342Whatever the object file is called, @code{@value{AS}} overwrites any 1343existing file of the same name. 1344 1345@node R 1346@section Join Data and Text Sections: @code{-R} 1347 1348@kindex -R 1349@cindex data and text sections, joining 1350@cindex text and data sections, joining 1351@cindex joining text and data sections 1352@cindex merging text and data sections 1353@code{-R} tells @code{@value{AS}} to write the object file as if all 1354data-section data lives in the text section. This is only done at 1355the very last moment: your binary data are the same, but data 1356section parts are relocated differently. The data section part of 1357your object file is zero bytes long because all its bytes are 1358appended to the text section. (@xref{Sections,,Sections and Relocation}.) 1359 1360When you specify @code{-R} it would be possible to generate shorter 1361address displacements (because we do not have to cross between text and 1362data section). We refrain from doing this simply for compatibility with 1363older versions of @code{@value{AS}}. In future, @code{-R} may work this way. 1364 1365@ifset COFF 1366When @code{@value{AS}} is configured for COFF output, 1367this option is only useful if you use sections named @samp{.text} and 1368@samp{.data}. 1369@end ifset 1370 1371@ifset HPPA 1372@code{-R} is not supported for any of the HPPA targets. Using 1373@code{-R} generates a warning from @code{@value{AS}}. 1374@end ifset 1375 1376@node statistics 1377@section Display Assembly Statistics: @code{--statistics} 1378 1379@kindex --statistics 1380@cindex statistics, about assembly 1381@cindex time, total for assembly 1382@cindex space used, maximum for assembly 1383Use @samp{--statistics} to display two statistics about the resources used by 1384@code{@value{AS}}: the maximum amount of space allocated during the assembly 1385(in bytes), and the total execution time taken for the assembly (in @sc{cpu} 1386seconds). 1387 1388@node traditional-format 1389@section Compatible output: @code{--traditional-format} 1390 1391@kindex --traditional-format 1392For some targets, the output of @code{@value{AS}} is different in some ways 1393from the output of some existing assembler. This switch requests 1394@code{@value{AS}} to use the traditional format instead. 1395 1396For example, it disables the exception frame optimizations which 1397@code{@value{AS}} normally does by default on @code{@value{GCC}} output. 1398 1399@node v 1400@section Announce Version: @code{-v} 1401 1402@kindex -v 1403@kindex -version 1404@cindex assembler version 1405@cindex version of assembler 1406You can find out what version of as is running by including the 1407option @samp{-v} (which you can also spell as @samp{-version}) on the 1408command line. 1409 1410@node W 1411@section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings} 1412 1413@code{@value{AS}} should never give a warning or error message when 1414assembling compiler output. But programs written by people often 1415cause @code{@value{AS}} to give a warning that a particular assumption was 1416made. All such warnings are directed to the standard error file. 1417 1418@kindex @samp{-W} 1419@kindex @samp{--no-warn} 1420@cindex suppressing warnings 1421@cindex warnings, suppressing 1422If you use the @code{-W} and @code{--no-warn} options, no warnings are issued. 1423This only affects the warning messages: it does not change any particular of 1424how @code{@value{AS}} assembles your file. Errors, which stop the assembly, 1425are still reported. 1426 1427@kindex @samp{--fatal-warnings} 1428@cindex errors, caused by warnings 1429@cindex warnings, causing error 1430If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers 1431files that generate warnings to be in error. 1432 1433@kindex @samp{--warn} 1434@cindex warnings, switching on 1435You can switch these options off again by specifying @code{--warn}, which 1436causes warnings to be output as usual. 1437 1438@node Z 1439@section Generate Object File in Spite of Errors: @code{-Z} 1440@cindex object file, after errors 1441@cindex errors, continuing after 1442After an error message, @code{@value{AS}} normally produces no output. If for 1443some reason you are interested in object file output even after 1444@code{@value{AS}} gives an error message on your program, use the @samp{-Z} 1445option. If there are any errors, @code{@value{AS}} continues anyways, and 1446writes an object file after a final warning message of the form @samp{@var{n} 1447errors, @var{m} warnings, generating bad object file.} 1448 1449@node Syntax 1450@chapter Syntax 1451 1452@cindex machine-independent syntax 1453@cindex syntax, machine-independent 1454This chapter describes the machine-independent syntax allowed in a 1455source file. @code{@value{AS}} syntax is similar to what many other 1456assemblers use; it is inspired by the BSD 4.2 1457@ifclear VAX 1458assembler. 1459@end ifclear 1460@ifset VAX 1461assembler, except that @code{@value{AS}} does not assemble Vax bit-fields. 1462@end ifset 1463 1464@menu 1465* Preprocessing:: Preprocessing 1466* Whitespace:: Whitespace 1467* Comments:: Comments 1468* Symbol Intro:: Symbols 1469* Statements:: Statements 1470* Constants:: Constants 1471@end menu 1472 1473@node Preprocessing 1474@section Preprocessing 1475 1476@cindex preprocessing 1477The @code{@value{AS}} internal preprocessor: 1478@itemize @bullet 1479@cindex whitespace, removed by preprocessor 1480@item 1481adjusts and removes extra whitespace. It leaves one space or tab before 1482the keywords on a line, and turns any other whitespace on the line into 1483a single space. 1484 1485@cindex comments, removed by preprocessor 1486@item 1487removes all comments, replacing them with a single space, or an 1488appropriate number of newlines. 1489 1490@cindex constants, converted by preprocessor 1491@item 1492converts character constants into the appropriate numeric values. 1493@end itemize 1494 1495It does not do macro processing, include file handling, or 1496anything else you may get from your C compiler's preprocessor. You can 1497do include file processing with the @code{.include} directive 1498(@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver 1499to get other ``CPP'' style preprocessing, by giving the input file a 1500@samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of 1501Output, gcc.info, Using GNU CC}. 1502 1503Excess whitespace, comments, and character constants 1504cannot be used in the portions of the input text that are not 1505preprocessed. 1506 1507@cindex turning preprocessing on and off 1508@cindex preprocessing, turning on and off 1509@kindex #NO_APP 1510@kindex #APP 1511If the first line of an input file is @code{#NO_APP} or if you use the 1512@samp{-f} option, whitespace and comments are not removed from the input file. 1513Within an input file, you can ask for whitespace and comment removal in 1514specific portions of the by putting a line that says @code{#APP} before the 1515text that may contain whitespace or comments, and putting a line that says 1516@code{#NO_APP} after this text. This feature is mainly intend to support 1517@code{asm} statements in compilers whose output is otherwise free of comments 1518and whitespace. 1519 1520@node Whitespace 1521@section Whitespace 1522 1523@cindex whitespace 1524@dfn{Whitespace} is one or more blanks or tabs, in any order. 1525Whitespace is used to separate symbols, and to make programs neater for 1526people to read. Unless within character constants 1527(@pxref{Characters,,Character Constants}), any whitespace means the same 1528as exactly one space. 1529 1530@node Comments 1531@section Comments 1532 1533@cindex comments 1534There are two ways of rendering comments to @code{@value{AS}}. In both 1535cases the comment is equivalent to one space. 1536 1537Anything from @samp{/*} through the next @samp{*/} is a comment. 1538This means you may not nest these comments. 1539 1540@smallexample 1541/* 1542 The only way to include a newline ('\n') in a comment 1543 is to use this sort of comment. 1544*/ 1545 1546/* This sort of comment does not nest. */ 1547@end smallexample 1548 1549@cindex line comment character 1550Anything from the @dfn{line comment} character to the next newline 1551is considered a comment and is ignored. The line comment character is 1552@ifset A29K 1553@samp{;} for the AMD 29K family; 1554@end ifset 1555@ifset ARC 1556@samp{;} on the ARC; 1557@end ifset 1558@ifset ARM 1559@samp{@@} on the ARM; 1560@end ifset 1561@ifset H8/300 1562@samp{;} for the H8/300 family; 1563@end ifset 1564@ifset H8/500 1565@samp{!} for the H8/500 family; 1566@end ifset 1567@ifset HPPA 1568@samp{;} for the HPPA; 1569@end ifset 1570@ifset I960 1571@samp{#} on the i960; 1572@end ifset 1573@ifset PJ 1574@samp{;} for picoJava; 1575@end ifset 1576@ifset SH 1577@samp{!} for the Hitachi SH; 1578@end ifset 1579@ifset SPARC 1580@samp{!} on the SPARC; 1581@end ifset 1582@ifset M32R 1583@samp{#} on the m32r; 1584@end ifset 1585@ifset M680X0 1586@samp{|} on the 680x0; 1587@end ifset 1588@ifset VAX 1589@samp{#} on the Vax; 1590@end ifset 1591@ifset Z8000 1592@samp{!} for the Z8000; 1593@end ifset 1594@ifset V850 1595@samp{#} on the V850; 1596@end ifset 1597see @ref{Machine Dependencies}. @refill 1598@c FIXME What about i386, m88k, i860? 1599 1600@ifset GENERIC 1601On some machines there are two different line comment characters. One 1602character only begins a comment if it is the first non-whitespace character on 1603a line, while the other always begins a comment. 1604@end ifset 1605 1606@ifset V850 1607The V850 assembler also supports a double dash as starting a comment that 1608extends to the end of the line. 1609 1610@samp{--}; 1611@end ifset 1612 1613@kindex # 1614@cindex lines starting with @code{#} 1615@cindex logical line numbers 1616To be compatible with past assemblers, lines that begin with @samp{#} have a 1617special interpretation. Following the @samp{#} should be an absolute 1618expression (@pxref{Expressions}): the logical line number of the @emph{next} 1619line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a 1620new logical file name. The rest of the line, if any, should be whitespace. 1621 1622If the first non-whitespace characters on the line are not numeric, 1623the line is ignored. (Just like a comment.) 1624 1625@smallexample 1626 # This is an ordinary comment. 1627# 42-6 "new_file_name" # New logical file name 1628 # This is logical line # 36. 1629@end smallexample 1630This feature is deprecated, and may disappear from future versions 1631of @code{@value{AS}}. 1632 1633@node Symbol Intro 1634@section Symbols 1635 1636@cindex characters used in symbols 1637@ifclear SPECIAL-SYMS 1638A @dfn{symbol} is one or more characters chosen from the set of all 1639letters (both upper and lower case), digits and the three characters 1640@samp{_.$}. 1641@end ifclear 1642@ifset SPECIAL-SYMS 1643@ifclear GENERIC 1644@ifset H8 1645A @dfn{symbol} is one or more characters chosen from the set of all 1646letters (both upper and lower case), digits and the three characters 1647@samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in 1648symbol names.) 1649@end ifset 1650@end ifclear 1651@end ifset 1652@ifset GENERIC 1653On most machines, you can also use @code{$} in symbol names; exceptions 1654are noted in @ref{Machine Dependencies}. 1655@end ifset 1656No symbol may begin with a digit. Case is significant. 1657There is no length limit: all characters are significant. Symbols are 1658delimited by characters not in that set, or by the beginning of a file 1659(since the source program must end with a newline, the end of a file is 1660not a possible symbol delimiter). @xref{Symbols}. 1661@cindex length of symbols 1662 1663@node Statements 1664@section Statements 1665 1666@cindex statements, structure of 1667@cindex line separator character 1668@cindex statement separator character 1669@ifclear GENERIC 1670@ifclear abnormal-separator 1671A @dfn{statement} ends at a newline character (@samp{\n}) or at a 1672semicolon (@samp{;}). The newline or semicolon is considered part of 1673the preceding statement. Newlines and semicolons within character 1674constants are an exception: they do not end statements. 1675@end ifclear 1676@ifset abnormal-separator 1677@ifset A29K 1678A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at'' 1679sign (@samp{@@}). The newline or at sign is considered part of the 1680preceding statement. Newlines and at signs within character constants 1681are an exception: they do not end statements. 1682@end ifset 1683@ifset HPPA 1684A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation 1685point (@samp{!}). The newline or exclamation point is considered part of the 1686preceding statement. Newlines and exclamation points within character 1687constants are an exception: they do not end statements. 1688@end ifset 1689@ifset H8 1690A @dfn{statement} ends at a newline character (@samp{\n}); or (for the 1691H8/300) a dollar sign (@samp{$}); or (for the 1692Hitachi-SH or the 1693H8/500) a semicolon 1694(@samp{;}). The newline or separator character is considered part of 1695the preceding statement. Newlines and separators within character 1696constants are an exception: they do not end statements. 1697@end ifset 1698@end ifset 1699@end ifclear 1700@ifset GENERIC 1701A @dfn{statement} ends at a newline character (@samp{\n}) or line 1702separator character. (The line separator is usually @samp{;}, unless 1703this conflicts with the comment character; @pxref{Machine Dependencies}.) The 1704newline or separator character is considered part of the preceding 1705statement. Newlines and separators within character constants are an 1706exception: they do not end statements. 1707@end ifset 1708 1709@cindex newline, required at file end 1710@cindex EOF, newline must precede 1711It is an error to end any statement with end-of-file: the last 1712character of any input file should be a newline.@refill 1713 1714An empty statement is allowed, and may include whitespace. It is ignored. 1715 1716@cindex instructions and directives 1717@cindex directives and instructions 1718@c "key symbol" is not used elsewhere in the document; seems pedantic to 1719@c @defn{} it in that case, as was done previously... doc@cygnus.com, 1720@c 13feb91. 1721A statement begins with zero or more labels, optionally followed by a 1722key symbol which determines what kind of statement it is. The key 1723symbol determines the syntax of the rest of the statement. If the 1724symbol begins with a dot @samp{.} then the statement is an assembler 1725directive: typically valid for any computer. If the symbol begins with 1726a letter the statement is an assembly language @dfn{instruction}: it 1727assembles into a machine language instruction. 1728@ifset GENERIC 1729Different versions of @code{@value{AS}} for different computers 1730recognize different instructions. In fact, the same symbol may 1731represent a different instruction in a different computer's assembly 1732language.@refill 1733@end ifset 1734 1735@cindex @code{:} (label) 1736@cindex label (@code{:}) 1737A label is a symbol immediately followed by a colon (@code{:}). 1738Whitespace before a label or after a colon is permitted, but you may not 1739have whitespace between a label's symbol and its colon. @xref{Labels}. 1740 1741@ifset HPPA 1742For HPPA targets, labels need not be immediately followed by a colon, but 1743the definition of a label must begin in column zero. This also implies that 1744only one label may be defined on each line. 1745@end ifset 1746 1747@smallexample 1748label: .directive followed by something 1749another_label: # This is an empty statement. 1750 instruction operand_1, operand_2, @dots{} 1751@end smallexample 1752 1753@node Constants 1754@section Constants 1755 1756@cindex constants 1757A constant is a number, written so that its value is known by 1758inspection, without knowing any context. Like this: 1759@smallexample 1760@group 1761.byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. 1762.ascii "Ring the bell\7" # A string constant. 1763.octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. 1764.float 0f-314159265358979323846264338327\ 176595028841971.693993751E-40 # - pi, a flonum. 1766@end group 1767@end smallexample 1768 1769@menu 1770* Characters:: Character Constants 1771* Numbers:: Number Constants 1772@end menu 1773 1774@node Characters 1775@subsection Character Constants 1776 1777@cindex character constants 1778@cindex constants, character 1779There are two kinds of character constants. A @dfn{character} stands 1780for one character in one byte and its value may be used in 1781numeric expressions. String constants (properly called string 1782@emph{literals}) are potentially many bytes and their values may not be 1783used in arithmetic expressions. 1784 1785@menu 1786* Strings:: Strings 1787* Chars:: Characters 1788@end menu 1789 1790@node Strings 1791@subsubsection Strings 1792 1793@cindex string constants 1794@cindex constants, string 1795A @dfn{string} is written between double-quotes. It may contain 1796double-quotes or null characters. The way to get special characters 1797into a string is to @dfn{escape} these characters: precede them with 1798a backslash @samp{\} character. For example @samp{\\} represents 1799one backslash: the first @code{\} is an escape which tells 1800@code{@value{AS}} to interpret the second character literally as a backslash 1801(which prevents @code{@value{AS}} from recognizing the second @code{\} as an 1802escape character). The complete list of escapes follows. 1803 1804@cindex escape codes, character 1805@cindex character escape codes 1806@table @kbd 1807@c @item \a 1808@c Mnemonic for ACKnowledge; for ASCII this is octal code 007. 1809@c 1810@cindex @code{\b} (backspace character) 1811@cindex backspace (@code{\b}) 1812@item \b 1813Mnemonic for backspace; for ASCII this is octal code 010. 1814 1815@c @item \e 1816@c Mnemonic for EOText; for ASCII this is octal code 004. 1817@c 1818@cindex @code{\f} (formfeed character) 1819@cindex formfeed (@code{\f}) 1820@item \f 1821Mnemonic for FormFeed; for ASCII this is octal code 014. 1822 1823@cindex @code{\n} (newline character) 1824@cindex newline (@code{\n}) 1825@item \n 1826Mnemonic for newline; for ASCII this is octal code 012. 1827 1828@c @item \p 1829@c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. 1830@c 1831@cindex @code{\r} (carriage return character) 1832@cindex carriage return (@code{\r}) 1833@item \r 1834Mnemonic for carriage-Return; for ASCII this is octal code 015. 1835 1836@c @item \s 1837@c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with 1838@c other assemblers. 1839@c 1840@cindex @code{\t} (tab) 1841@cindex tab (@code{\t}) 1842@item \t 1843Mnemonic for horizontal Tab; for ASCII this is octal code 011. 1844 1845@c @item \v 1846@c Mnemonic for Vertical tab; for ASCII this is octal code 013. 1847@c @item \x @var{digit} @var{digit} @var{digit} 1848@c A hexadecimal character code. The numeric code is 3 hexadecimal digits. 1849@c 1850@cindex @code{\@var{ddd}} (octal character code) 1851@cindex octal character code (@code{\@var{ddd}}) 1852@item \ @var{digit} @var{digit} @var{digit} 1853An octal character code. The numeric code is 3 octal digits. 1854For compatibility with other Unix systems, 8 and 9 are accepted as digits: 1855for example, @code{\008} has the value 010, and @code{\009} the value 011. 1856 1857@cindex @code{\@var{xd...}} (hex character code) 1858@cindex hex character code (@code{\@var{xd...}}) 1859@item \@code{x} @var{hex-digits...} 1860A hex character code. All trailing hex digits are combined. Either upper or 1861lower case @code{x} works. 1862 1863@cindex @code{\\} (@samp{\} character) 1864@cindex backslash (@code{\\}) 1865@item \\ 1866Represents one @samp{\} character. 1867 1868@c @item \' 1869@c Represents one @samp{'} (accent acute) character. 1870@c This is needed in single character literals 1871@c (@xref{Characters,,Character Constants}.) to represent 1872@c a @samp{'}. 1873@c 1874@cindex @code{\"} (doublequote character) 1875@cindex doublequote (@code{\"}) 1876@item \" 1877Represents one @samp{"} character. Needed in strings to represent 1878this character, because an unescaped @samp{"} would end the string. 1879 1880@item \ @var{anything-else} 1881Any other character when escaped by @kbd{\} gives a warning, but 1882assembles as if the @samp{\} was not present. The idea is that if 1883you used an escape sequence you clearly didn't want the literal 1884interpretation of the following character. However @code{@value{AS}} has no 1885other interpretation, so @code{@value{AS}} knows it is giving you the wrong 1886code and warns you of the fact. 1887@end table 1888 1889Which characters are escapable, and what those escapes represent, 1890varies widely among assemblers. The current set is what we think 1891the BSD 4.2 assembler recognizes, and is a subset of what most C 1892compilers recognize. If you are in doubt, do not use an escape 1893sequence. 1894 1895@node Chars 1896@subsubsection Characters 1897 1898@cindex single character constant 1899@cindex character, single 1900@cindex constant, single character 1901A single character may be written as a single quote immediately 1902followed by that character. The same escapes apply to characters as 1903to strings. So if you want to write the character backslash, you 1904must write @kbd{'\\} where the first @code{\} escapes the second 1905@code{\}. As you can see, the quote is an acute accent, not a 1906grave accent. A newline 1907@ifclear GENERIC 1908@ifclear abnormal-separator 1909(or semicolon @samp{;}) 1910@end ifclear 1911@ifset abnormal-separator 1912@ifset A29K 1913(or at sign @samp{@@}) 1914@end ifset 1915@ifset H8 1916(or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the 1917Hitachi SH or 1918H8/500) 1919@end ifset 1920@end ifset 1921@end ifclear 1922immediately following an acute accent is taken as a literal character 1923and does not count as the end of a statement. The value of a character 1924constant in a numeric expression is the machine's byte-wide code for 1925that character. @code{@value{AS}} assumes your character code is ASCII: 1926@kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill 1927 1928@node Numbers 1929@subsection Number Constants 1930 1931@cindex constants, number 1932@cindex number constants 1933@code{@value{AS}} distinguishes three kinds of numbers according to how they 1934are stored in the target machine. @emph{Integers} are numbers that 1935would fit into an @code{int} in the C language. @emph{Bignums} are 1936integers, but they are stored in more than 32 bits. @emph{Flonums} 1937are floating point numbers, described below. 1938 1939@menu 1940* Integers:: Integers 1941* Bignums:: Bignums 1942* Flonums:: Flonums 1943@ifclear GENERIC 1944@ifset I960 1945* Bit Fields:: Bit Fields 1946@end ifset 1947@end ifclear 1948@end menu 1949 1950@node Integers 1951@subsubsection Integers 1952@cindex integers 1953@cindex constants, integer 1954 1955@cindex binary integers 1956@cindex integers, binary 1957A binary integer is @samp{0b} or @samp{0B} followed by zero or more of 1958the binary digits @samp{01}. 1959 1960@cindex octal integers 1961@cindex integers, octal 1962An octal integer is @samp{0} followed by zero or more of the octal 1963digits (@samp{01234567}). 1964 1965@cindex decimal integers 1966@cindex integers, decimal 1967A decimal integer starts with a non-zero digit followed by zero or 1968more digits (@samp{0123456789}). 1969 1970@cindex hexadecimal integers 1971@cindex integers, hexadecimal 1972A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or 1973more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. 1974 1975Integers have the usual values. To denote a negative integer, use 1976the prefix operator @samp{-} discussed under expressions 1977(@pxref{Prefix Ops,,Prefix Operators}). 1978 1979@node Bignums 1980@subsubsection Bignums 1981 1982@cindex bignums 1983@cindex constants, bignum 1984A @dfn{bignum} has the same syntax and semantics as an integer 1985except that the number (or its negative) takes more than 32 bits to 1986represent in binary. The distinction is made because in some places 1987integers are permitted while bignums are not. 1988 1989@node Flonums 1990@subsubsection Flonums 1991@cindex flonums 1992@cindex floating point numbers 1993@cindex constants, floating point 1994 1995@cindex precision, floating point 1996A @dfn{flonum} represents a floating point number. The translation is 1997indirect: a decimal floating point number from the text is converted by 1998@code{@value{AS}} to a generic binary floating point number of more than 1999sufficient precision. This generic floating point number is converted 2000to a particular computer's floating point format (or formats) by a 2001portion of @code{@value{AS}} specialized to that computer. 2002 2003A flonum is written by writing (in order) 2004@itemize @bullet 2005@item 2006The digit @samp{0}. 2007@ifset HPPA 2008(@samp{0} is optional on the HPPA.) 2009@end ifset 2010 2011@item 2012A letter, to tell @code{@value{AS}} the rest of the number is a flonum. 2013@ifset GENERIC 2014@kbd{e} is recommended. Case is not important. 2015@ignore 2016@c FIXME: verify if flonum syntax really this vague for most cases 2017(Any otherwise illegal letter works here, but that might be changed. Vax BSD 20184.2 assembler seems to allow any of @samp{defghDEFGH}.) 2019@end ignore 2020 2021On the H8/300, H8/500, 2022Hitachi SH, 2023and AMD 29K architectures, the letter must be 2024one of the letters @samp{DFPRSX} (in upper or lower case). 2025 2026On the ARC, the letter must be one of the letters @samp{DFRS} 2027(in upper or lower case). 2028 2029On the Intel 960 architecture, the letter must be 2030one of the letters @samp{DFT} (in upper or lower case). 2031 2032On the HPPA architecture, the letter must be @samp{E} (upper case only). 2033@end ifset 2034@ifclear GENERIC 2035@ifset A29K 2036One of the letters @samp{DFPRSX} (in upper or lower case). 2037@end ifset 2038@ifset ARC 2039One of the letters @samp{DFRS} (in upper or lower case). 2040@end ifset 2041@ifset H8 2042One of the letters @samp{DFPRSX} (in upper or lower case). 2043@end ifset 2044@ifset HPPA 2045The letter @samp{E} (upper case only). 2046@end ifset 2047@ifset I960 2048One of the letters @samp{DFT} (in upper or lower case). 2049@end ifset 2050@end ifclear 2051 2052@item 2053An optional sign: either @samp{+} or @samp{-}. 2054 2055@item 2056An optional @dfn{integer part}: zero or more decimal digits. 2057 2058@item 2059An optional @dfn{fractional part}: @samp{.} followed by zero 2060or more decimal digits. 2061 2062@item 2063An optional exponent, consisting of: 2064 2065@itemize @bullet 2066@item 2067An @samp{E} or @samp{e}. 2068@c I can't find a config where "EXP_CHARS" is other than 'eE', but in 2069@c principle this can perfectly well be different on different targets. 2070@item 2071Optional sign: either @samp{+} or @samp{-}. 2072@item 2073One or more decimal digits. 2074@end itemize 2075 2076@end itemize 2077 2078At least one of the integer part or the fractional part must be 2079present. The floating point number has the usual base-10 value. 2080 2081@code{@value{AS}} does all processing using integers. Flonums are computed 2082independently of any floating point hardware in the computer running 2083@code{@value{AS}}. 2084 2085@ifclear GENERIC 2086@ifset I960 2087@c Bit fields are written as a general facility but are also controlled 2088@c by a conditional-compilation flag---which is as of now (21mar91) 2089@c turned on only by the i960 config of GAS. 2090@node Bit Fields 2091@subsubsection Bit Fields 2092 2093@cindex bit fields 2094@cindex constants, bit field 2095You can also define numeric constants as @dfn{bit fields}. 2096specify two numbers separated by a colon--- 2097@example 2098@var{mask}:@var{value} 2099@end example 2100@noindent 2101@code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and 2102@var{value}. 2103 2104The resulting number is then packed 2105@ifset GENERIC 2106@c this conditional paren in case bit fields turned on elsewhere than 960 2107(in host-dependent byte order) 2108@end ifset 2109into a field whose width depends on which assembler directive has the 2110bit-field as its argument. Overflow (a result from the bitwise and 2111requiring more binary digits to represent) is not an error; instead, 2112more constants are generated, of the specified width, beginning with the 2113least significant digits.@refill 2114 2115The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, 2116@code{.short}, and @code{.word} accept bit-field arguments. 2117@end ifset 2118@end ifclear 2119 2120@node Sections 2121@chapter Sections and Relocation 2122@cindex sections 2123@cindex relocation 2124 2125@menu 2126* Secs Background:: Background 2127* Ld Sections:: Linker Sections 2128* As Sections:: Assembler Internal Sections 2129* Sub-Sections:: Sub-Sections 2130* bss:: bss Section 2131@end menu 2132 2133@node Secs Background 2134@section Background 2135 2136Roughly, a section is a range of addresses, with no gaps; all data 2137``in'' those addresses is treated the same for some particular purpose. 2138For example there may be a ``read only'' section. 2139 2140@cindex linker, and assembler 2141@cindex assembler, and linker 2142The linker @code{@value{LD}} reads many object files (partial programs) and 2143combines their contents to form a runnable program. When @code{@value{AS}} 2144emits an object file, the partial program is assumed to start at address 0. 2145@code{@value{LD}} assigns the final addresses for the partial program, so that 2146different partial programs do not overlap. This is actually an 2147oversimplification, but it suffices to explain how @code{@value{AS}} uses 2148sections. 2149 2150@code{@value{LD}} moves blocks of bytes of your program to their run-time 2151addresses. These blocks slide to their run-time addresses as rigid 2152units; their length does not change and neither does the order of bytes 2153within them. Such a rigid unit is called a @emph{section}. Assigning 2154run-time addresses to sections is called @dfn{relocation}. It includes 2155the task of adjusting mentions of object-file addresses so they refer to 2156the proper run-time addresses. 2157@ifset H8 2158For the H8/300 and H8/500, 2159and for the Hitachi SH, 2160@code{@value{AS}} pads sections if needed to 2161ensure they end on a word (sixteen bit) boundary. 2162@end ifset 2163 2164@cindex standard assembler sections 2165An object file written by @code{@value{AS}} has at least three sections, any 2166of which may be empty. These are named @dfn{text}, @dfn{data} and 2167@dfn{bss} sections. 2168 2169@ifset COFF 2170@ifset GENERIC 2171When it generates COFF output, 2172@end ifset 2173@code{@value{AS}} can also generate whatever other named sections you specify 2174using the @samp{.section} directive (@pxref{Section,,@code{.section}}). 2175If you do not use any directives that place output in the @samp{.text} 2176or @samp{.data} sections, these sections still exist, but are empty. 2177@end ifset 2178 2179@ifset HPPA 2180@ifset GENERIC 2181When @code{@value{AS}} generates SOM or ELF output for the HPPA, 2182@end ifset 2183@code{@value{AS}} can also generate whatever other named sections you 2184specify using the @samp{.space} and @samp{.subspace} directives. See 2185@cite{HP9000 Series 800 Assembly Language Reference Manual} 2186(HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} 2187assembler directives. 2188 2189@ifset SOM 2190Additionally, @code{@value{AS}} uses different names for the standard 2191text, data, and bss sections when generating SOM output. Program text 2192is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and 2193BSS into @samp{$BSS$}. 2194@end ifset 2195@end ifset 2196 2197Within the object file, the text section starts at address @code{0}, the 2198data section follows, and the bss section follows the data section. 2199 2200@ifset HPPA 2201When generating either SOM or ELF output files on the HPPA, the text 2202section starts at address @code{0}, the data section at address 2203@code{0x4000000}, and the bss section follows the data section. 2204@end ifset 2205 2206To let @code{@value{LD}} know which data changes when the sections are 2207relocated, and how to change that data, @code{@value{AS}} also writes to the 2208object file details of the relocation needed. To perform relocation 2209@code{@value{LD}} must know, each time an address in the object 2210file is mentioned: 2211@itemize @bullet 2212@item 2213Where in the object file is the beginning of this reference to 2214an address? 2215@item 2216How long (in bytes) is this reference? 2217@item 2218Which section does the address refer to? What is the numeric value of 2219@display 2220(@var{address}) @minus{} (@var{start-address of section})? 2221@end display 2222@item 2223Is the reference to an address ``Program-Counter relative''? 2224@end itemize 2225 2226@cindex addresses, format of 2227@cindex section-relative addressing 2228In fact, every address @code{@value{AS}} ever uses is expressed as 2229@display 2230(@var{section}) + (@var{offset into section}) 2231@end display 2232@noindent 2233Further, most expressions @code{@value{AS}} computes have this section-relative 2234nature. 2235@ifset SOM 2236(For some object formats, such as SOM for the HPPA, some expressions are 2237symbol-relative instead.) 2238@end ifset 2239 2240In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset 2241@var{N} into section @var{secname}.'' 2242 2243Apart from text, data and bss sections you need to know about the 2244@dfn{absolute} section. When @code{@value{LD}} mixes partial programs, 2245addresses in the absolute section remain unchanged. For example, address 2246@code{@{absolute 0@}} is ``relocated'' to run-time address 0 by 2247@code{@value{LD}}. Although the linker never arranges two partial programs' 2248data sections with overlapping addresses after linking, @emph{by definition} 2249their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one 2250part of a program is always the same address when the program is running as 2251address @code{@{absolute@ 239@}} in any other part of the program. 2252 2253The idea of sections is extended to the @dfn{undefined} section. Any 2254address whose section is unknown at assembly time is by definition 2255rendered @{undefined @var{U}@}---where @var{U} is filled in later. 2256Since numbers are always defined, the only way to generate an undefined 2257address is to mention an undefined symbol. A reference to a named 2258common block would be such a symbol: its value is unknown at assembly 2259time so it has section @emph{undefined}. 2260 2261By analogy the word @emph{section} is used to describe groups of sections in 2262the linked program. @code{@value{LD}} puts all partial programs' text 2263sections in contiguous addresses in the linked program. It is 2264customary to refer to the @emph{text section} of a program, meaning all 2265the addresses of all partial programs' text sections. Likewise for 2266data and bss sections. 2267 2268Some sections are manipulated by @code{@value{LD}}; others are invented for 2269use of @code{@value{AS}} and have no meaning except during assembly. 2270 2271@node Ld Sections 2272@section Linker Sections 2273@code{@value{LD}} deals with just four kinds of sections, summarized below. 2274 2275@table @strong 2276 2277@ifset COFF 2278@cindex named sections 2279@cindex sections, named 2280@item named sections 2281@end ifset 2282@ifset aout-bout 2283@cindex text section 2284@cindex data section 2285@itemx text section 2286@itemx data section 2287@end ifset 2288These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as 2289separate but equal sections. Anything you can say of one section is 2290true another. 2291@ifset aout-bout 2292When the program is running, however, it is 2293customary for the text section to be unalterable. The 2294text section is often shared among processes: it contains 2295instructions, constants and the like. The data section of a running 2296program is usually alterable: for example, C variables would be stored 2297in the data section. 2298@end ifset 2299 2300@cindex bss section 2301@item bss section 2302This section contains zeroed bytes when your program begins running. It 2303is used to hold unitialized variables or common storage. The length of 2304each partial program's bss section is important, but because it starts 2305out containing zeroed bytes there is no need to store explicit zero 2306bytes in the object file. The bss section was invented to eliminate 2307those explicit zeros from object files. 2308 2309@cindex absolute section 2310@item absolute section 2311Address 0 of this section is always ``relocated'' to runtime address 0. 2312This is useful if you want to refer to an address that @code{@value{LD}} must 2313not change when relocating. In this sense we speak of absolute 2314addresses being ``unrelocatable'': they do not change during relocation. 2315 2316@cindex undefined section 2317@item undefined section 2318This ``section'' is a catch-all for address references to objects not in 2319the preceding sections. 2320@c FIXME: ref to some other doc on obj-file formats could go here. 2321@end table 2322 2323@cindex relocation example 2324An idealized example of three relocatable sections follows. 2325@ifset COFF 2326The example uses the traditional section names @samp{.text} and @samp{.data}. 2327@end ifset 2328Memory addresses are on the horizontal axis. 2329 2330@c TEXI2ROFF-KILL 2331@ifinfo 2332@c END TEXI2ROFF-KILL 2333@smallexample 2334 +-----+----+--+ 2335partial program # 1: |ttttt|dddd|00| 2336 +-----+----+--+ 2337 2338 text data bss 2339 seg. seg. seg. 2340 2341 +---+---+---+ 2342partial program # 2: |TTT|DDD|000| 2343 +---+---+---+ 2344 2345 +--+---+-----+--+----+---+-----+~~ 2346linked program: | |TTT|ttttt| |dddd|DDD|00000| 2347 +--+---+-----+--+----+---+-----+~~ 2348 2349 addresses: 0 @dots{} 2350@end smallexample 2351@c TEXI2ROFF-KILL 2352@end ifinfo 2353@need 5000 2354@tex 2355 2356\line{\it Partial program \#1: \hfil} 2357\line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} 2358\line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} 2359 2360\line{\it Partial program \#2: \hfil} 2361\line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} 2362\line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} 2363 2364\line{\it linked program: \hfil} 2365\line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} 2366\line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt 2367ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt 2368DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} 2369 2370\line{\it addresses: \hfil} 2371\line{0\dots\hfil} 2372 2373@end tex 2374@c END TEXI2ROFF-KILL 2375 2376@node As Sections 2377@section Assembler Internal Sections 2378 2379@cindex internal assembler sections 2380@cindex sections in messages, internal 2381These sections are meant only for the internal use of @code{@value{AS}}. They 2382have no meaning at run-time. You do not really need to know about these 2383sections for most purposes; but they can be mentioned in @code{@value{AS}} 2384warning messages, so it might be helpful to have an idea of their 2385meanings to @code{@value{AS}}. These sections are used to permit the 2386value of every expression in your assembly language program to be a 2387section-relative address. 2388 2389@table @b 2390@cindex assembler internal logic error 2391@item ASSEMBLER-INTERNAL-LOGIC-ERROR! 2392An internal assembler logic error has been found. This means there is a 2393bug in the assembler. 2394 2395@cindex expr (internal section) 2396@item expr section 2397The assembler stores complex expression internally as combinations of 2398symbols. When it needs to represent an expression as a symbol, it puts 2399it in the expr section. 2400@c FIXME item debug 2401@c FIXME item transfer[t] vector preload 2402@c FIXME item transfer[t] vector postload 2403@c FIXME item register 2404@end table 2405 2406@node Sub-Sections 2407@section Sub-Sections 2408 2409@cindex numbered subsections 2410@cindex grouping data 2411@ifset aout-bout 2412Assembled bytes 2413@ifset COFF 2414conventionally 2415@end ifset 2416fall into two sections: text and data. 2417@end ifset 2418You may have separate groups of 2419@ifset GENERIC 2420data in named sections 2421@end ifset 2422@ifclear GENERIC 2423@ifclear aout-bout 2424data in named sections 2425@end ifclear 2426@ifset aout-bout 2427text or data 2428@end ifset 2429@end ifclear 2430that you want to end up near to each other in the object file, even though they 2431are not contiguous in the assembler source. @code{@value{AS}} allows you to 2432use @dfn{subsections} for this purpose. Within each section, there can be 2433numbered subsections with values from 0 to 8192. Objects assembled into the 2434same subsection go into the object file together with other objects in the same 2435subsection. For example, a compiler might want to store constants in the text 2436section, but might not want to have them interspersed with the program being 2437assembled. In this case, the compiler could issue a @samp{.text 0} before each 2438section of code being output, and a @samp{.text 1} before each group of 2439constants being output. 2440 2441Subsections are optional. If you do not use subsections, everything 2442goes in subsection number zero. 2443 2444@ifset GENERIC 2445Each subsection is zero-padded up to a multiple of four bytes. 2446(Subsections may be padded a different amount on different flavors 2447of @code{@value{AS}}.) 2448@end ifset 2449@ifclear GENERIC 2450@ifset H8 2451On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word 2452boundary (two bytes). 2453The same is true on the Hitachi SH. 2454@end ifset 2455@ifset I960 2456@c FIXME section padding (alignment)? 2457@c Rich Pixley says padding here depends on target obj code format; that 2458@c doesn't seem particularly useful to say without further elaboration, 2459@c so for now I say nothing about it. If this is a generic BFD issue, 2460@c these paragraphs might need to vanish from this manual, and be 2461@c discussed in BFD chapter of binutils (or some such). 2462@end ifset 2463@ifset A29K 2464On the AMD 29K family, no particular padding is added to section or 2465subsection sizes; @value{AS} forces no alignment on this platform. 2466@end ifset 2467@end ifclear 2468 2469Subsections appear in your object file in numeric order, lowest numbered 2470to highest. (All this to be compatible with other people's assemblers.) 2471The object file contains no representation of subsections; @code{@value{LD}} and 2472other programs that manipulate object files see no trace of them. 2473They just see all your text subsections as a text section, and all your 2474data subsections as a data section. 2475 2476To specify which subsection you want subsequent statements assembled 2477into, use a numeric argument to specify it, in a @samp{.text 2478@var{expression}} or a @samp{.data @var{expression}} statement. 2479@ifset COFF 2480@ifset GENERIC 2481When generating COFF output, you 2482@end ifset 2483@ifclear GENERIC 2484You 2485@end ifclear 2486can also use an extra subsection 2487argument with arbitrary named sections: @samp{.section @var{name}, 2488@var{expression}}. 2489@end ifset 2490@var{Expression} should be an absolute expression. 2491(@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0} 2492is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly 2493begins in @code{text 0}. For instance: 2494@smallexample 2495.text 0 # The default subsection is text 0 anyway. 2496.ascii "This lives in the first text subsection. *" 2497.text 1 2498.ascii "But this lives in the second text subsection." 2499.data 0 2500.ascii "This lives in the data section," 2501.ascii "in the first data subsection." 2502.text 0 2503.ascii "This lives in the first text section," 2504.ascii "immediately following the asterisk (*)." 2505@end smallexample 2506 2507Each section has a @dfn{location counter} incremented by one for every byte 2508assembled into that section. Because subsections are merely a convenience 2509restricted to @code{@value{AS}} there is no concept of a subsection location 2510counter. There is no way to directly manipulate a location counter---but the 2511@code{.align} directive changes it, and any label definition captures its 2512current value. The location counter of the section where statements are being 2513assembled is said to be the @dfn{active} location counter. 2514 2515@node bss 2516@section bss Section 2517 2518@cindex bss section 2519@cindex common variable storage 2520The bss section is used for local common variable storage. 2521You may allocate address space in the bss section, but you may 2522not dictate data to load into it before your program executes. When 2523your program starts running, all the contents of the bss 2524section are zeroed bytes. 2525 2526The @code{.lcomm} pseudo-op defines a symbol in the bss section; see 2527@ref{Lcomm,,@code{.lcomm}}. 2528 2529The @code{.comm} pseudo-op may be used to declare a common symbol, which is 2530another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}. 2531 2532@ifset GENERIC 2533When assembling for a target which supports multiple sections, such as ELF or 2534COFF, you may switch into the @code{.bss} section and define symbols as usual; 2535see @ref{Section,,@code{.section}}. You may only assemble zero values into the 2536section. Typically the section will only contain symbol definitions and 2537@code{.skip} directives (@pxref{Skip,,@code{.skip}}). 2538@end ifset 2539 2540@node Symbols 2541@chapter Symbols 2542 2543@cindex symbols 2544Symbols are a central concept: the programmer uses symbols to name 2545things, the linker uses symbols to link, and the debugger uses symbols 2546to debug. 2547 2548@quotation 2549@cindex debuggers, and symbol order 2550@emph{Warning:} @code{@value{AS}} does not place symbols in the object file in 2551the same order they were declared. This may break some debuggers. 2552@end quotation 2553 2554@menu 2555* Labels:: Labels 2556* Setting Symbols:: Giving Symbols Other Values 2557* Symbol Names:: Symbol Names 2558* Dot:: The Special Dot Symbol 2559* Symbol Attributes:: Symbol Attributes 2560@end menu 2561 2562@node Labels 2563@section Labels 2564 2565@cindex labels 2566A @dfn{label} is written as a symbol immediately followed by a colon 2567@samp{:}. The symbol then represents the current value of the 2568active location counter, and is, for example, a suitable instruction 2569operand. You are warned if you use the same symbol to represent two 2570different locations: the first definition overrides any other 2571definitions. 2572 2573@ifset HPPA 2574On the HPPA, the usual form for a label need not be immediately followed by a 2575colon, but instead must start in column zero. Only one label may be defined on 2576a single line. To work around this, the HPPA version of @code{@value{AS}} also 2577provides a special directive @code{.label} for defining labels more flexibly. 2578@end ifset 2579 2580@node Setting Symbols 2581@section Giving Symbols Other Values 2582 2583@cindex assigning values to symbols 2584@cindex symbol values, assigning 2585A symbol can be given an arbitrary value by writing a symbol, followed 2586by an equals sign @samp{=}, followed by an expression 2587(@pxref{Expressions}). This is equivalent to using the @code{.set} 2588directive. @xref{Set,,@code{.set}}. 2589 2590@node Symbol Names 2591@section Symbol Names 2592 2593@cindex symbol names 2594@cindex names, symbol 2595@ifclear SPECIAL-SYMS 2596Symbol names begin with a letter or with one of @samp{._}. On most 2597machines, you can also use @code{$} in symbol names; exceptions are 2598noted in @ref{Machine Dependencies}. That character may be followed by any 2599string of digits, letters, dollar signs (unless otherwise noted in 2600@ref{Machine Dependencies}), and underscores. 2601@end ifclear 2602@ifset A29K 2603For the AMD 29K family, @samp{?} is also allowed in the 2604body of a symbol name, though not at its beginning. 2605@end ifset 2606 2607@ifset SPECIAL-SYMS 2608@ifset H8 2609Symbol names begin with a letter or with one of @samp{._}. On the 2610Hitachi SH or the 2611H8/500, you can also use @code{$} in symbol names. That character may 2612be followed by any string of digits, letters, dollar signs (save on the 2613H8/300), and underscores. 2614@end ifset 2615@end ifset 2616 2617Case of letters is significant: @code{foo} is a different symbol name 2618than @code{Foo}. 2619 2620Each symbol has exactly one name. Each name in an assembly language program 2621refers to exactly one symbol. You may use that symbol name any number of times 2622in a program. 2623 2624@subheading Local Symbol Names 2625 2626@cindex local symbol names 2627@cindex symbol names, local 2628@cindex temporary symbol names 2629@cindex symbol names, temporary 2630Local symbols help compilers and programmers use names temporarily. 2631There are ten local symbol names, which are re-used throughout the 2632program. You may refer to them using the names @samp{0} @samp{1} 2633@dots{} @samp{9}. To define a local symbol, write a label of the form 2634@samp{@b{N}:} (where @b{N} represents any digit). To refer to the most 2635recent previous definition of that symbol write @samp{@b{N}b}, using the 2636same digit as when you defined the label. To refer to the next 2637definition of a local label, write @samp{@b{N}f}---where @b{N} gives you 2638a choice of 10 forward references. The @samp{b} stands for 2639``backwards'' and the @samp{f} stands for ``forwards''. 2640 2641Local symbols are not emitted by the current @sc{gnu} C compiler. 2642 2643There is no restriction on how you can use these labels, but 2644remember that at any point in the assembly you can refer to at most 264510 prior local labels and to at most 10 forward local labels. 2646 2647Local symbol names are only a notation device. They are immediately 2648transformed into more conventional symbol names before the assembler 2649uses them. The symbol names stored in the symbol table, appearing in 2650error messages and optionally emitted to the object file have these 2651parts: 2652 2653@table @code 2654@item L 2655All local labels begin with @samp{L}. Normally both @code{@value{AS}} and 2656@code{@value{LD}} forget symbols that start with @samp{L}. These labels are 2657used for symbols you are never intended to see. If you use the 2658@samp{-L} option then @code{@value{AS}} retains these symbols in the 2659object file. If you also instruct @code{@value{LD}} to retain these symbols, 2660you may use them in debugging. 2661 2662@item @var{digit} 2663If the label is written @samp{0:} then the digit is @samp{0}. 2664If the label is written @samp{1:} then the digit is @samp{1}. 2665And so on up through @samp{9:}. 2666 2667@item @kbd{C-A} 2668This unusual character is included so you do not accidentally invent 2669a symbol of the same name. The character has ASCII value 2670@samp{\001}. 2671 2672@item @emph{ordinal number} 2673This is a serial number to keep the labels distinct. The first 2674@samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the 2675number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:} 2676through @samp{9:}. 2677@end table 2678 2679For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th 2680@code{3:} is named @code{L3@kbd{C-A}44}. 2681 2682@node Dot 2683@section The Special Dot Symbol 2684 2685@cindex dot (symbol) 2686@cindex @code{.} (symbol) 2687@cindex current address 2688@cindex location counter 2689The special symbol @samp{.} refers to the current address that 2690@code{@value{AS}} is assembling into. Thus, the expression @samp{melvin: 2691.long .} defines @code{melvin} to contain its own address. 2692Assigning a value to @code{.} is treated the same as a @code{.org} 2693directive. Thus, the expression @samp{.=.+4} is the same as saying 2694@ifclear no-space-dir 2695@samp{.space 4}. 2696@end ifclear 2697@ifset no-space-dir 2698@ifset A29K 2699@samp{.block 4}. 2700@end ifset 2701@end ifset 2702 2703@node Symbol Attributes 2704@section Symbol Attributes 2705 2706@cindex symbol attributes 2707@cindex attributes, symbol 2708Every symbol has, as well as its name, the attributes ``Value'' and 2709``Type''. Depending on output format, symbols can also have auxiliary 2710attributes. 2711@ifset INTERNALS 2712The detailed definitions are in @file{a.out.h}. 2713@end ifset 2714 2715If you use a symbol without defining it, @code{@value{AS}} assumes zero for 2716all these attributes, and probably won't warn you. This makes the 2717symbol an externally defined symbol, which is generally what you 2718would want. 2719 2720@menu 2721* Symbol Value:: Value 2722* Symbol Type:: Type 2723@ifset aout-bout 2724@ifset GENERIC 2725* a.out Symbols:: Symbol Attributes: @code{a.out} 2726@end ifset 2727@ifclear GENERIC 2728@ifclear BOUT 2729* a.out Symbols:: Symbol Attributes: @code{a.out} 2730@end ifclear 2731@ifset BOUT 2732* a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} 2733@end ifset 2734@end ifclear 2735@end ifset 2736@ifset COFF 2737* COFF Symbols:: Symbol Attributes for COFF 2738@end ifset 2739@ifset SOM 2740* SOM Symbols:: Symbol Attributes for SOM 2741@end ifset 2742@end menu 2743 2744@node Symbol Value 2745@subsection Value 2746 2747@cindex value of a symbol 2748@cindex symbol value 2749The value of a symbol is (usually) 32 bits. For a symbol which labels a 2750location in the text, data, bss or absolute sections the value is the 2751number of addresses from the start of that section to the label. 2752Naturally for text, data and bss sections the value of a symbol changes 2753as @code{@value{LD}} changes section base addresses during linking. Absolute 2754symbols' values do not change during linking: that is why they are 2755called absolute. 2756 2757The value of an undefined symbol is treated in a special way. If it is 27580 then the symbol is not defined in this assembler source file, and 2759@code{@value{LD}} tries to determine its value from other files linked into the 2760same program. You make this kind of symbol simply by mentioning a symbol 2761name without defining it. A non-zero value represents a @code{.comm} 2762common declaration. The value is how much common storage to reserve, in 2763bytes (addresses). The symbol refers to the first address of the 2764allocated storage. 2765 2766@node Symbol Type 2767@subsection Type 2768 2769@cindex type of a symbol 2770@cindex symbol type 2771The type attribute of a symbol contains relocation (section) 2772information, any flag settings indicating that a symbol is external, and 2773(optionally), other information for linkers and debuggers. The exact 2774format depends on the object-code output format in use. 2775 2776@ifset aout-bout 2777@ifclear GENERIC 2778@ifset BOUT 2779@c The following avoids a "widow" subsection title. @group would be 2780@c better if it were available outside examples. 2781@need 1000 2782@node a.out Symbols 2783@subsection Symbol Attributes: @code{a.out}, @code{b.out} 2784 2785@cindex @code{b.out} symbol attributes 2786@cindex symbol attributes, @code{b.out} 2787These symbol attributes appear only when @code{@value{AS}} is configured for 2788one of the Berkeley-descended object output formats---@code{a.out} or 2789@code{b.out}. 2790 2791@end ifset 2792@ifclear BOUT 2793@node a.out Symbols 2794@subsection Symbol Attributes: @code{a.out} 2795 2796@cindex @code{a.out} symbol attributes 2797@cindex symbol attributes, @code{a.out} 2798 2799@end ifclear 2800@end ifclear 2801@ifset GENERIC 2802@node a.out Symbols 2803@subsection Symbol Attributes: @code{a.out} 2804 2805@cindex @code{a.out} symbol attributes 2806@cindex symbol attributes, @code{a.out} 2807 2808@end ifset 2809@menu 2810* Symbol Desc:: Descriptor 2811* Symbol Other:: Other 2812@end menu 2813 2814@node Symbol Desc 2815@subsubsection Descriptor 2816 2817@cindex descriptor, of @code{a.out} symbol 2818This is an arbitrary 16-bit value. You may establish a symbol's 2819descriptor value by using a @code{.desc} statement 2820(@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to 2821@code{@value{AS}}. 2822 2823@node Symbol Other 2824@subsubsection Other 2825 2826@cindex other attribute, of @code{a.out} symbol 2827This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}. 2828@end ifset 2829 2830@ifset COFF 2831@node COFF Symbols 2832@subsection Symbol Attributes for COFF 2833 2834@cindex COFF symbol attributes 2835@cindex symbol attributes, COFF 2836 2837The COFF format supports a multitude of auxiliary symbol attributes; 2838like the primary symbol attributes, they are set between @code{.def} and 2839@code{.endef} directives. 2840 2841@subsubsection Primary Attributes 2842 2843@cindex primary attributes, COFF symbols 2844The symbol name is set with @code{.def}; the value and type, 2845respectively, with @code{.val} and @code{.type}. 2846 2847@subsubsection Auxiliary Attributes 2848 2849@cindex auxiliary attributes, COFF symbols 2850The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, 2851@code{.size}, and @code{.tag} can generate auxiliary symbol table 2852information for COFF. 2853@end ifset 2854 2855@ifset SOM 2856@node SOM Symbols 2857@subsection Symbol Attributes for SOM 2858 2859@cindex SOM symbol attributes 2860@cindex symbol attributes, SOM 2861 2862The SOM format for the HPPA supports a multitude of symbol attributes set with 2863the @code{.EXPORT} and @code{.IMPORT} directives. 2864 2865The attributes are described in @cite{HP9000 Series 800 Assembly 2866Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and 2867@code{EXPORT} assembler directive documentation. 2868@end ifset 2869 2870@node Expressions 2871@chapter Expressions 2872 2873@cindex expressions 2874@cindex addresses 2875@cindex numeric values 2876An @dfn{expression} specifies an address or numeric value. 2877Whitespace may precede and/or follow an expression. 2878 2879The result of an expression must be an absolute number, or else an offset into 2880a particular section. If an expression is not absolute, and there is not 2881enough information when @code{@value{AS}} sees the expression to know its 2882section, a second pass over the source program might be necessary to interpret 2883the expression---but the second pass is currently not implemented. 2884@code{@value{AS}} aborts with an error message in this situation. 2885 2886@menu 2887* Empty Exprs:: Empty Expressions 2888* Integer Exprs:: Integer Expressions 2889@end menu 2890 2891@node Empty Exprs 2892@section Empty Expressions 2893 2894@cindex empty expressions 2895@cindex expressions, empty 2896An empty expression has no value: it is just whitespace or null. 2897Wherever an absolute expression is required, you may omit the 2898expression, and @code{@value{AS}} assumes a value of (absolute) 0. This 2899is compatible with other assemblers. 2900 2901@node Integer Exprs 2902@section Integer Expressions 2903 2904@cindex integer expressions 2905@cindex expressions, integer 2906An @dfn{integer expression} is one or more @emph{arguments} delimited 2907by @emph{operators}. 2908 2909@menu 2910* Arguments:: Arguments 2911* Operators:: Operators 2912* Prefix Ops:: Prefix Operators 2913* Infix Ops:: Infix Operators 2914@end menu 2915 2916@node Arguments 2917@subsection Arguments 2918 2919@cindex expression arguments 2920@cindex arguments in expressions 2921@cindex operands in expressions 2922@cindex arithmetic operands 2923@dfn{Arguments} are symbols, numbers or subexpressions. In other 2924contexts arguments are sometimes called ``arithmetic operands''. In 2925this manual, to avoid confusing them with the ``instruction operands'' of 2926the machine language, we use the term ``argument'' to refer to parts of 2927expressions only, reserving the word ``operand'' to refer only to machine 2928instruction operands. 2929 2930Symbols are evaluated to yield @{@var{section} @var{NNN}@} where 2931@var{section} is one of text, data, bss, absolute, 2932or undefined. @var{NNN} is a signed, 2's complement 32 bit 2933integer. 2934 2935Numbers are usually integers. 2936 2937A number can be a flonum or bignum. In this case, you are warned 2938that only the low order 32 bits are used, and @code{@value{AS}} pretends 2939these 32 bits are an integer. You may write integer-manipulating 2940instructions that act on exotic constants, compatible with other 2941assemblers. 2942 2943@cindex subexpressions 2944Subexpressions are a left parenthesis @samp{(} followed by an integer 2945expression, followed by a right parenthesis @samp{)}; or a prefix 2946operator followed by an argument. 2947 2948@node Operators 2949@subsection Operators 2950 2951@cindex operators, in expressions 2952@cindex arithmetic functions 2953@cindex functions, in expressions 2954@dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix 2955operators are followed by an argument. Infix operators appear 2956between their arguments. Operators may be preceded and/or followed by 2957whitespace. 2958 2959@node Prefix Ops 2960@subsection Prefix Operator 2961 2962@cindex prefix operators 2963@code{@value{AS}} has the following @dfn{prefix operators}. They each take 2964one argument, which must be absolute. 2965 2966@c the tex/end tex stuff surrounding this small table is meant to make 2967@c it align, on the printed page, with the similar table in the next 2968@c section (which is inside an enumerate). 2969@tex 2970\global\advance\leftskip by \itemindent 2971@end tex 2972 2973@table @code 2974@item - 2975@dfn{Negation}. Two's complement negation. 2976@item ~ 2977@dfn{Complementation}. Bitwise not. 2978@end table 2979 2980@tex 2981\global\advance\leftskip by -\itemindent 2982@end tex 2983 2984@node Infix Ops 2985@subsection Infix Operators 2986 2987@cindex infix operators 2988@cindex operators, permitted arguments 2989@dfn{Infix operators} take two arguments, one on either side. Operators 2990have precedence, but operations with equal precedence are performed left 2991to right. Apart from @code{+} or @code{-}, both arguments must be 2992absolute, and the result is absolute. 2993 2994@enumerate 2995@cindex operator precedence 2996@cindex precedence of operators 2997 2998@item 2999Highest Precedence 3000 3001@table @code 3002@item * 3003@dfn{Multiplication}. 3004 3005@item / 3006@dfn{Division}. Truncation is the same as the C operator @samp{/} 3007 3008@item % 3009@dfn{Remainder}. 3010 3011@item < 3012@itemx << 3013@dfn{Shift Left}. Same as the C operator @samp{<<}. 3014 3015@item > 3016@itemx >> 3017@dfn{Shift Right}. Same as the C operator @samp{>>}. 3018@end table 3019 3020@item 3021Intermediate precedence 3022 3023@table @code 3024@item | 3025 3026@dfn{Bitwise Inclusive Or}. 3027 3028@item & 3029@dfn{Bitwise And}. 3030 3031@item ^ 3032@dfn{Bitwise Exclusive Or}. 3033 3034@item ! 3035@dfn{Bitwise Or Not}. 3036@end table 3037 3038@item 3039Lowest Precedence 3040 3041@table @code 3042@cindex addition, permitted arguments 3043@cindex plus, permitted arguments 3044@cindex arguments for addition 3045@item + 3046@dfn{Addition}. If either argument is absolute, the result has the section of 3047the other argument. You may not add together arguments from different 3048sections. 3049 3050@cindex subtraction, permitted arguments 3051@cindex minus, permitted arguments 3052@cindex arguments for subtraction 3053@item - 3054@dfn{Subtraction}. If the right argument is absolute, the 3055result has the section of the left argument. 3056If both arguments are in the same section, the result is absolute. 3057You may not subtract arguments from different sections. 3058@c FIXME is there still something useful to say about undefined - undefined ? 3059@end table 3060@end enumerate 3061 3062In short, it's only meaningful to add or subtract the @emph{offsets} in an 3063address; you can only have a defined section in one of the two arguments. 3064 3065@node Pseudo Ops 3066@chapter Assembler Directives 3067 3068@cindex directives, machine independent 3069@cindex pseudo-ops, machine independent 3070@cindex machine independent directives 3071All assembler directives have names that begin with a period (@samp{.}). 3072The rest of the name is letters, usually in lower case. 3073 3074This chapter discusses directives that are available regardless of the 3075target machine configuration for the @sc{gnu} assembler. 3076@ifset GENERIC 3077Some machine configurations provide additional directives. 3078@xref{Machine Dependencies}. 3079@end ifset 3080@ifclear GENERIC 3081@ifset machine-directives 3082@xref{Machine Dependencies} for additional directives. 3083@end ifset 3084@end ifclear 3085 3086@menu 3087* Abort:: @code{.abort} 3088@ifset COFF 3089* ABORT:: @code{.ABORT} 3090@end ifset 3091 3092* Align:: @code{.align @var{abs-expr} , @var{abs-expr}} 3093* Ascii:: @code{.ascii "@var{string}"}@dots{} 3094* Asciz:: @code{.asciz "@var{string}"}@dots{} 3095* Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} 3096* Byte:: @code{.byte @var{expressions}} 3097* Comm:: @code{.comm @var{symbol} , @var{length} } 3098* Data:: @code{.data @var{subsection}} 3099@ifset COFF 3100* Def:: @code{.def @var{name}} 3101@end ifset 3102@ifset aout-bout 3103* Desc:: @code{.desc @var{symbol}, @var{abs-expression}} 3104@end ifset 3105@ifset COFF 3106* Dim:: @code{.dim} 3107@end ifset 3108 3109* Double:: @code{.double @var{flonums}} 3110* Eject:: @code{.eject} 3111* Else:: @code{.else} 3112* Elseif:: @code{.elseif} 3113* End:: @code{.end} 3114@ifset COFF 3115* Endef:: @code{.endef} 3116@end ifset 3117 3118* Endfunc:: @code{.endfunc} 3119* Endif:: @code{.endif} 3120* Equ:: @code{.equ @var{symbol}, @var{expression}} 3121* Equiv:: @code{.equiv @var{symbol}, @var{expression}} 3122* Err:: @code{.err} 3123* Exitm:: @code{.exitm} 3124* Extern:: @code{.extern} 3125* Fail:: @code{.fail} 3126@ifclear no-file-dir 3127* File:: @code{.file @var{string}} 3128@end ifclear 3129 3130* Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} 3131* Float:: @code{.float @var{flonums}} 3132* Func:: @code{.func} 3133* Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} 3134* hword:: @code{.hword @var{expressions}} 3135* Ident:: @code{.ident} 3136* If:: @code{.if @var{absolute expression}} 3137* Include:: @code{.include "@var{file}"} 3138* Int:: @code{.int @var{expressions}} 3139* Irp:: @code{.irp @var{symbol},@var{values}}@dots{} 3140* Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} 3141* Lcomm:: @code{.lcomm @var{symbol} , @var{length}} 3142* Lflags:: @code{.lflags} 3143@ifclear no-line-dir 3144* Line:: @code{.line @var{line-number}} 3145@end ifclear 3146 3147* Ln:: @code{.ln @var{line-number}} 3148* Linkonce:: @code{.linkonce [@var{type}]} 3149* List:: @code{.list} 3150* Long:: @code{.long @var{expressions}} 3151@ignore 3152* Lsym:: @code{.lsym @var{symbol}, @var{expression}} 3153@end ignore 3154 3155* Macro:: @code{.macro @var{name} @var{args}}@dots{} 3156* MRI:: @code{.mri @var{val}} 3157 3158* Nolist:: @code{.nolist} 3159* Octa:: @code{.octa @var{bignums}} 3160* Org:: @code{.org @var{new-lc} , @var{fill}} 3161* P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}} 3162* Print:: @code{.print @var{string}} 3163* Psize:: @code{.psize @var{lines}, @var{columns}} 3164* Purgem:: @code{.purgem @var{name}} 3165* Quad:: @code{.quad @var{bignums}} 3166* Rept:: @code{.rept @var{count}} 3167* Sbttl:: @code{.sbttl "@var{subheading}"} 3168@ifset COFF 3169* Scl:: @code{.scl @var{class}} 3170* Section:: @code{.section @var{name}, @var{subsection}} 3171@end ifset 3172 3173* Set:: @code{.set @var{symbol}, @var{expression}} 3174* Short:: @code{.short @var{expressions}} 3175* Single:: @code{.single @var{flonums}} 3176@ifset COFF 3177* Size:: @code{.size} 3178@end ifset 3179 3180* Skip:: @code{.skip @var{size} , @var{fill}} 3181* Sleb128:: @code{.sleb128 @var{expressions}} 3182* Space:: @code{.space @var{size} , @var{fill}} 3183@ifset have-stabs 3184* Stab:: @code{.stabd, .stabn, .stabs} 3185@end ifset 3186 3187* String:: @code{.string "@var{str}"} 3188* Struct:: @code{.struct @var{expression}} 3189@ifset ELF 3190* Symver:: @code{.symver @var{name},@var{name2@@nodename}} 3191@end ifset 3192@ifset COFF 3193* Tag:: @code{.tag @var{structname}} 3194@end ifset 3195 3196* Text:: @code{.text @var{subsection}} 3197* Title:: @code{.title "@var{heading}"} 3198@ifset COFF 3199* Type:: @code{.type @var{int}} 3200* Val:: @code{.val @var{addr}} 3201@end ifset 3202@ifset ELF 3203* Visibility:: @code{.internal @var{name}, .hidden @var{name}, .protected @var{name}} 3204@end ifset 3205 3206* Uleb128:: @code{.uleb128 @var{expressions}} 3207* Word:: @code{.word @var{expressions}} 3208* Deprecated:: Deprecated Directives 3209@end menu 3210 3211@node Abort 3212@section @code{.abort} 3213 3214@cindex @code{abort} directive 3215@cindex stopping the assembly 3216This directive stops the assembly immediately. It is for 3217compatibility with other assemblers. The original idea was that the 3218assembly language source would be piped into the assembler. If the sender 3219of the source quit, it could use this directive tells @code{@value{AS}} to 3220quit also. One day @code{.abort} will not be supported. 3221 3222@ifset COFF 3223@node ABORT 3224@section @code{.ABORT} 3225 3226@cindex @code{ABORT} directive 3227When producing COFF output, @code{@value{AS}} accepts this directive as a 3228synonym for @samp{.abort}. 3229 3230@ifset BOUT 3231When producing @code{b.out} output, @code{@value{AS}} accepts this directive, 3232but ignores it. 3233@end ifset 3234@end ifset 3235 3236@node Align 3237@section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 3238 3239@cindex padding the location counter 3240@cindex @code{align} directive 3241Pad the location counter (in the current subsection) to a particular storage 3242boundary. The first expression (which must be absolute) is the alignment 3243required, as described below. 3244 3245The second expression (also absolute) gives the fill value to be stored in the 3246padding bytes. It (and the comma) may be omitted. If it is omitted, the 3247padding bytes are normally zero. However, on some systems, if the section is 3248marked as containing code and the fill value is omitted, the space is filled 3249with no-op instructions. 3250 3251The third expression is also absolute, and is also optional. If it is present, 3252it is the maximum number of bytes that should be skipped by this alignment 3253directive. If doing the alignment would require skipping more bytes than the 3254specified maximum, then the alignment is not done at all. You can omit the 3255fill value (the second argument) entirely by simply using two commas after the 3256required alignment; this can be useful if you want the alignment to be filled 3257with no-op instructions when appropriate. 3258 3259The way the required alignment is specified varies from system to system. 3260For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF 3261format, 3262the first expression is the 3263alignment request in bytes. For example @samp{.align 8} advances 3264the location counter until it is a multiple of 8. If the location counter 3265is already a multiple of 8, no change is needed. 3266 3267For other systems, including the i386 using a.out format, it is the 3268number of low-order zero bits the location counter must have after 3269advancement. For example @samp{.align 3} advances the location 3270counter until it a multiple of 8. If the location counter is already a 3271multiple of 8, no change is needed. 3272 3273This inconsistency is due to the different behaviors of the various 3274native assemblers for these systems which GAS must emulate. 3275GAS also provides @code{.balign} and @code{.p2align} directives, 3276described later, which have a consistent behavior across all 3277architectures (but are specific to GAS). 3278 3279@node Ascii 3280@section @code{.ascii "@var{string}"}@dots{} 3281 3282@cindex @code{ascii} directive 3283@cindex string literals 3284@code{.ascii} expects zero or more string literals (@pxref{Strings}) 3285separated by commas. It assembles each string (with no automatic 3286trailing zero byte) into consecutive addresses. 3287 3288@node Asciz 3289@section @code{.asciz "@var{string}"}@dots{} 3290 3291@cindex @code{asciz} directive 3292@cindex zero-terminated strings 3293@cindex null-terminated strings 3294@code{.asciz} is just like @code{.ascii}, but each string is followed by 3295a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. 3296 3297@node Balign 3298@section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 3299 3300@cindex padding the location counter given number of bytes 3301@cindex @code{balign} directive 3302Pad the location counter (in the current subsection) to a particular 3303storage boundary. The first expression (which must be absolute) is the 3304alignment request in bytes. For example @samp{.balign 8} advances 3305the location counter until it is a multiple of 8. If the location counter 3306is already a multiple of 8, no change is needed. 3307 3308The second expression (also absolute) gives the fill value to be stored in the 3309padding bytes. It (and the comma) may be omitted. If it is omitted, the 3310padding bytes are normally zero. However, on some systems, if the section is 3311marked as containing code and the fill value is omitted, the space is filled 3312with no-op instructions. 3313 3314The third expression is also absolute, and is also optional. If it is present, 3315it is the maximum number of bytes that should be skipped by this alignment 3316directive. If doing the alignment would require skipping more bytes than the 3317specified maximum, then the alignment is not done at all. You can omit the 3318fill value (the second argument) entirely by simply using two commas after the 3319required alignment; this can be useful if you want the alignment to be filled 3320with no-op instructions when appropriate. 3321 3322@cindex @code{balignw} directive 3323@cindex @code{balignl} directive 3324The @code{.balignw} and @code{.balignl} directives are variants of the 3325@code{.balign} directive. The @code{.balignw} directive treats the fill 3326pattern as a two byte word value. The @code{.balignl} directives treats the 3327fill pattern as a four byte longword value. For example, @code{.balignw 33284,0x368d} will align to a multiple of 4. If it skips two bytes, they will be 3329filled in with the value 0x368d (the exact placement of the bytes depends upon 3330the endianness of the processor). If it skips 1 or 3 bytes, the fill value is 3331undefined. 3332 3333@node Byte 3334@section @code{.byte @var{expressions}} 3335 3336@cindex @code{byte} directive 3337@cindex integers, one byte 3338@code{.byte} expects zero or more expressions, separated by commas. 3339Each expression is assembled into the next byte. 3340 3341@node Comm 3342@section @code{.comm @var{symbol} , @var{length} } 3343 3344@cindex @code{comm} directive 3345@cindex symbol, common 3346@code{.comm} declares a common symbol named @var{symbol}. When linking, a 3347common symbol in one object file may be merged with a defined or common symbol 3348of the same name in another object file. If @code{@value{LD}} does not see a 3349definition for the symbol--just one or more common symbols--then it will 3350allocate @var{length} bytes of uninitialized memory. @var{length} must be an 3351absolute expression. If @code{@value{LD}} sees multiple common symbols with 3352the same name, and they do not all have the same size, it will allocate space 3353using the largest size. 3354 3355@ifset ELF 3356When using ELF, the @code{.comm} directive takes an optional third argument. 3357This is the desired alignment of the symbol, specified as a byte boundary (for 3358example, an alignment of 16 means that the least significant 4 bits of the 3359address should be zero). The alignment must be an absolute expression, and it 3360must be a power of two. If @code{@value{LD}} allocates uninitialized memory 3361for the common symbol, it will use the alignment when placing the symbol. If 3362no alignment is specified, @code{@value{AS}} will set the alignment to the 3363largest power of two less than or equal to the size of the symbol, up to a 3364maximum of 16. 3365@end ifset 3366 3367@ifset HPPA 3368The syntax for @code{.comm} differs slightly on the HPPA. The syntax is 3369@samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. 3370@end ifset 3371 3372@node Data 3373@section @code{.data @var{subsection}} 3374 3375@cindex @code{data} directive 3376@code{.data} tells @code{@value{AS}} to assemble the following statements onto the 3377end of the data subsection numbered @var{subsection} (which is an 3378absolute expression). If @var{subsection} is omitted, it defaults 3379to zero. 3380 3381@ifset COFF 3382@node Def 3383@section @code{.def @var{name}} 3384 3385@cindex @code{def} directive 3386@cindex COFF symbols, debugging 3387@cindex debugging COFF symbols 3388Begin defining debugging information for a symbol @var{name}; the 3389definition extends until the @code{.endef} directive is encountered. 3390@ifset BOUT 3391 3392This directive is only observed when @code{@value{AS}} is configured for COFF 3393format output; when producing @code{b.out}, @samp{.def} is recognized, 3394but ignored. 3395@end ifset 3396@end ifset 3397 3398@ifset aout-bout 3399@node Desc 3400@section @code{.desc @var{symbol}, @var{abs-expression}} 3401 3402@cindex @code{desc} directive 3403@cindex COFF symbol descriptor 3404@cindex symbol descriptor, COFF 3405This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) 3406to the low 16 bits of an absolute expression. 3407 3408@ifset COFF 3409The @samp{.desc} directive is not available when @code{@value{AS}} is 3410configured for COFF output; it is only for @code{a.out} or @code{b.out} 3411object format. For the sake of compatibility, @code{@value{AS}} accepts 3412it, but produces no output, when configured for COFF. 3413@end ifset 3414@end ifset 3415 3416@ifset COFF 3417@node Dim 3418@section @code{.dim} 3419 3420@cindex @code{dim} directive 3421@cindex COFF auxiliary symbol information 3422@cindex auxiliary symbol information, COFF 3423This directive is generated by compilers to include auxiliary debugging 3424information in the symbol table. It is only permitted inside 3425@code{.def}/@code{.endef} pairs. 3426@ifset BOUT 3427 3428@samp{.dim} is only meaningful when generating COFF format output; when 3429@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 3430ignores it. 3431@end ifset 3432@end ifset 3433 3434@node Double 3435@section @code{.double @var{flonums}} 3436 3437@cindex @code{double} directive 3438@cindex floating point numbers (double) 3439@code{.double} expects zero or more flonums, separated by commas. It 3440assembles floating point numbers. 3441@ifset GENERIC 3442The exact kind of floating point numbers emitted depends on how 3443@code{@value{AS}} is configured. @xref{Machine Dependencies}. 3444@end ifset 3445@ifclear GENERIC 3446@ifset IEEEFLOAT 3447On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers 3448in @sc{ieee} format. 3449@end ifset 3450@end ifclear 3451 3452@node Eject 3453@section @code{.eject} 3454 3455@cindex @code{eject} directive 3456@cindex new page, in listings 3457@cindex page, in listings 3458@cindex listing control: new page 3459Force a page break at this point, when generating assembly listings. 3460 3461@node Else 3462@section @code{.else} 3463 3464@cindex @code{else} directive 3465@code{.else} is part of the @code{@value{AS}} support for conditional 3466assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section 3467of code to be assembled if the condition for the preceding @code{.if} 3468was false. 3469 3470@node Elseif 3471@section @code{.elseif} 3472 3473@cindex @code{elseif} directive 3474@code{.elseif} is part of the @code{@value{AS}} support for conditional 3475assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new 3476@code{.if} block that would otherwise fill the entire @code{.else} section. 3477 3478@node End 3479@section @code{.end} 3480 3481@cindex @code{end} directive 3482@code{.end} marks the end of the assembly file. @code{@value{AS}} does not 3483process anything in the file past the @code{.end} directive. 3484 3485@ifset COFF 3486@node Endef 3487@section @code{.endef} 3488 3489@cindex @code{endef} directive 3490This directive flags the end of a symbol definition begun with 3491@code{.def}. 3492@ifset BOUT 3493 3494@samp{.endef} is only meaningful when generating COFF format output; if 3495@code{@value{AS}} is configured to generate @code{b.out}, it accepts this 3496directive but ignores it. 3497@end ifset 3498@end ifset 3499 3500@node Endfunc 3501@section @code{.endfunc} 3502@cindex @code{endfunc} directive 3503@code{.endfunc} marks the end of a function specified with @code{.func}. 3504 3505@node Endif 3506@section @code{.endif} 3507 3508@cindex @code{endif} directive 3509@code{.endif} is part of the @code{@value{AS}} support for conditional assembly; 3510it marks the end of a block of code that is only assembled 3511conditionally. @xref{If,,@code{.if}}. 3512 3513@node Equ 3514@section @code{.equ @var{symbol}, @var{expression}} 3515 3516@cindex @code{equ} directive 3517@cindex assigning values to symbols 3518@cindex symbols, assigning values to 3519This directive sets the value of @var{symbol} to @var{expression}. 3520It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}. 3521 3522@ifset HPPA 3523The syntax for @code{equ} on the HPPA is 3524@samp{@var{symbol} .equ @var{expression}}. 3525@end ifset 3526 3527@node Equiv 3528@section @code{.equiv @var{symbol}, @var{expression}} 3529@cindex @code{equiv} directive 3530The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that 3531the assembler will signal an error if @var{symbol} is already defined. 3532 3533Except for the contents of the error message, this is roughly equivalent to 3534@smallexample 3535.ifdef SYM 3536.err 3537.endif 3538.equ SYM,VAL 3539@end smallexample 3540 3541@node Err 3542@section @code{.err} 3543@cindex @code{err} directive 3544If @code{@value{AS}} assembles a @code{.err} directive, it will print an error 3545message and, unless the @code{-Z} option was used, it will not generate an 3546object file. This can be used to signal error an conditionally compiled code. 3547 3548@node Exitm 3549@section @code{.exitm} 3550Exit early from the current macro definition. @xref{Macro}. 3551 3552@node Extern 3553@section @code{.extern} 3554 3555@cindex @code{extern} directive 3556@code{.extern} is accepted in the source program---for compatibility 3557with other assemblers---but it is ignored. @code{@value{AS}} treats 3558all undefined symbols as external. 3559 3560@node Fail 3561@section @code{.fail @var{expression}} 3562 3563@cindex @code{fail} directive 3564Generates an error or a warning. If the value of the @var{expression} is 500 3565or more, @code{@value{AS}} will print a warning message. If the value is less 3566than 500, @code{@value{AS}} will print an error message. The message will 3567include the value of @var{expression}. This can occasionally be useful inside 3568complex nested macros or conditional assembly. 3569 3570@ifclear no-file-dir 3571@node File 3572@section @code{.file @var{string}} 3573 3574@cindex @code{file} directive 3575@cindex logical file name 3576@cindex file name, logical 3577@code{.file} tells @code{@value{AS}} that we are about to start a new logical 3578file. @var{string} is the new file name. In general, the filename is 3579recognized whether or not it is surrounded by quotes @samp{"}; but if you wish 3580to specify an empty file name, you must give the quotes--@code{""}. This 3581statement may go away in future: it is only recognized to be compatible with 3582old @code{@value{AS}} programs. 3583@ifset A29K 3584In some configurations of @code{@value{AS}}, @code{.file} has already been 3585removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}. 3586@end ifset 3587@end ifclear 3588 3589@node Fill 3590@section @code{.fill @var{repeat} , @var{size} , @var{value}} 3591 3592@cindex @code{fill} directive 3593@cindex writing patterns in memory 3594@cindex patterns, writing in memory 3595@var{result}, @var{size} and @var{value} are absolute expressions. 3596This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} 3597may be zero or more. @var{Size} may be zero or more, but if it is 3598more than 8, then it is deemed to have the value 8, compatible with 3599other people's assemblers. The contents of each @var{repeat} bytes 3600is taken from an 8-byte number. The highest order 4 bytes are 3601zero. The lowest order 4 bytes are @var{value} rendered in the 3602byte-order of an integer on the computer @code{@value{AS}} is assembling for. 3603Each @var{size} bytes in a repetition is taken from the lowest order 3604@var{size} bytes of this number. Again, this bizarre behavior is 3605compatible with other people's assemblers. 3606 3607@var{size} and @var{value} are optional. 3608If the second comma and @var{value} are absent, @var{value} is 3609assumed zero. If the first comma and following tokens are absent, 3610@var{size} is assumed to be 1. 3611 3612@node Float 3613@section @code{.float @var{flonums}} 3614 3615@cindex floating point numbers (single) 3616@cindex @code{float} directive 3617This directive assembles zero or more flonums, separated by commas. It 3618has the same effect as @code{.single}. 3619@ifset GENERIC 3620The exact kind of floating point numbers emitted depends on how 3621@code{@value{AS}} is configured. 3622@xref{Machine Dependencies}. 3623@end ifset 3624@ifclear GENERIC 3625@ifset IEEEFLOAT 3626On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers 3627in @sc{ieee} format. 3628@end ifset 3629@end ifclear 3630 3631@node Func 3632@section @code{.func @var{name}[,@var{label}]} 3633@cindex @code{func} directive 3634@code{.func} emits debugging information to denote function @var{name}, and 3635is ignored unless the file is assembled with debugging enabled. 3636Only @samp{--gstabs} is currently supported. 3637@var{label} is the entry point of the function and if omitted @var{name} 3638prepended with the @samp{leading char} is used. 3639@samp{leading char} is usually @code{_} or nothing, depending on the target. 3640All functions are currently defined to have @code{void} return type. 3641The function must be terminated with @code{.endfunc}. 3642 3643@node Global 3644@section @code{.global @var{symbol}}, @code{.globl @var{symbol}} 3645 3646@cindex @code{global} directive 3647@cindex symbol, making visible to linker 3648@code{.global} makes the symbol visible to @code{@value{LD}}. If you define 3649@var{symbol} in your partial program, its value is made available to 3650other partial programs that are linked with it. Otherwise, 3651@var{symbol} takes its attributes from a symbol of the same name 3652from another file linked into the same program. 3653 3654Both spellings (@samp{.globl} and @samp{.global}) are accepted, for 3655compatibility with other assemblers. 3656 3657@ifset HPPA 3658On the HPPA, @code{.global} is not always enough to make it accessible to other 3659partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. 3660@xref{HPPA Directives,, HPPA Assembler Directives}. 3661@end ifset 3662 3663@node hword 3664@section @code{.hword @var{expressions}} 3665 3666@cindex @code{hword} directive 3667@cindex integers, 16-bit 3668@cindex numbers, 16-bit 3669@cindex sixteen bit integers 3670This expects zero or more @var{expressions}, and emits 3671a 16 bit number for each. 3672 3673@ifset GENERIC 3674This directive is a synonym for @samp{.short}; depending on the target 3675architecture, it may also be a synonym for @samp{.word}. 3676@end ifset 3677@ifclear GENERIC 3678@ifset W32 3679This directive is a synonym for @samp{.short}. 3680@end ifset 3681@ifset W16 3682This directive is a synonym for both @samp{.short} and @samp{.word}. 3683@end ifset 3684@end ifclear 3685 3686@node Ident 3687@section @code{.ident} 3688 3689@cindex @code{ident} directive 3690This directive is used by some assemblers to place tags in object files. 3691@code{@value{AS}} simply accepts the directive for source-file 3692compatibility with such assemblers, but does not actually emit anything 3693for it. 3694 3695@node If 3696@section @code{.if @var{absolute expression}} 3697 3698@cindex conditional assembly 3699@cindex @code{if} directive 3700@code{.if} marks the beginning of a section of code which is only 3701considered part of the source program being assembled if the argument 3702(which must be an @var{absolute expression}) is non-zero. The end of 3703the conditional section of code must be marked by @code{.endif} 3704(@pxref{Endif,,@code{.endif}}); optionally, you may include code for the 3705alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). 3706If you have several conditions to check, @code{.elseif} may be used to avoid 3707nesting blocks if/else within each subsequent @code{.else} block. 3708 3709The following variants of @code{.if} are also supported: 3710@table @code 3711@cindex @code{ifdef} directive 3712@item .ifdef @var{symbol} 3713Assembles the following section of code if the specified @var{symbol} 3714has been defined. 3715 3716@cindex @code{ifc} directive 3717@item .ifc @var{string1},@var{string2} 3718Assembles the following section of code if the two strings are the same. The 3719strings may be optionally quoted with single quotes. If they are not quoted, 3720the first string stops at the first comma, and the second string stops at the 3721end of the line. Strings which contain whitespace should be quoted. The 3722string comparison is case sensitive. 3723 3724@cindex @code{ifeq} directive 3725@item .ifeq @var{absolute expression} 3726Assembles the following section of code if the argument is zero. 3727 3728@cindex @code{ifeqs} directive 3729@item .ifeqs @var{string1},@var{string2} 3730Another form of @code{.ifc}. The strings must be quoted using double quotes. 3731 3732@cindex @code{ifge} directive 3733@item .ifge @var{absolute expression} 3734Assembles the following section of code if the argument is greater than or 3735equal to zero. 3736 3737@cindex @code{ifgt} directive 3738@item .ifgt @var{absolute expression} 3739Assembles the following section of code if the argument is greater than zero. 3740 3741@cindex @code{ifle} directive 3742@item .ifle @var{absolute expression} 3743Assembles the following section of code if the argument is less than or equal 3744to zero. 3745 3746@cindex @code{iflt} directive 3747@item .iflt @var{absolute expression} 3748Assembles the following section of code if the argument is less than zero. 3749 3750@cindex @code{ifnc} directive 3751@item .ifnc @var{string1},@var{string2}. 3752Like @code{.ifc}, but the sense of the test is reversed: this assembles the 3753following section of code if the two strings are not the same. 3754 3755@cindex @code{ifndef} directive 3756@cindex @code{ifnotdef} directive 3757@item .ifndef @var{symbol} 3758@itemx .ifnotdef @var{symbol} 3759Assembles the following section of code if the specified @var{symbol} 3760has not been defined. Both spelling variants are equivalent. 3761 3762@cindex @code{ifne} directive 3763@item .ifne @var{absolute expression} 3764Assembles the following section of code if the argument is not equal to zero 3765(in other words, this is equivalent to @code{.if}). 3766 3767@cindex @code{ifnes} directive 3768@item .ifnes @var{string1},@var{string2} 3769Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the 3770following section of code if the two strings are not the same. 3771@end table 3772 3773@node Include 3774@section @code{.include "@var{file}"} 3775 3776@cindex @code{include} directive 3777@cindex supporting files, including 3778@cindex files, including 3779This directive provides a way to include supporting files at specified 3780points in your source program. The code from @var{file} is assembled as 3781if it followed the point of the @code{.include}; when the end of the 3782included file is reached, assembly of the original file continues. You 3783can control the search paths used with the @samp{-I} command-line option 3784(@pxref{Invoking,,Command-Line Options}). Quotation marks are required 3785around @var{file}. 3786 3787@node Int 3788@section @code{.int @var{expressions}} 3789 3790@cindex @code{int} directive 3791@cindex integers, 32-bit 3792Expect zero or more @var{expressions}, of any section, separated by commas. 3793For each expression, emit a number that, at run time, is the value of that 3794expression. The byte order and bit size of the number depends on what kind 3795of target the assembly is for. 3796 3797@ifclear GENERIC 3798@ifset H8 3799On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit 3800integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits 380132-bit integers. 3802@end ifset 3803@end ifclear 3804 3805@node Irp 3806@section @code{.irp @var{symbol},@var{values}}@dots{} 3807 3808@cindex @code{irp} directive 3809Evaluate a sequence of statements assigning different values to @var{symbol}. 3810The sequence of statements starts at the @code{.irp} directive, and is 3811terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is 3812set to @var{value}, and the sequence of statements is assembled. If no 3813@var{value} is listed, the sequence of statements is assembled once, with 3814@var{symbol} set to the null string. To refer to @var{symbol} within the 3815sequence of statements, use @var{\symbol}. 3816 3817For example, assembling 3818 3819@example 3820 .irp param,1,2,3 3821 move d\param,sp@@- 3822 .endr 3823@end example 3824 3825is equivalent to assembling 3826 3827@example 3828 move d1,sp@@- 3829 move d2,sp@@- 3830 move d3,sp@@- 3831@end example 3832 3833@node Irpc 3834@section @code{.irpc @var{symbol},@var{values}}@dots{} 3835 3836@cindex @code{irpc} directive 3837Evaluate a sequence of statements assigning different values to @var{symbol}. 3838The sequence of statements starts at the @code{.irpc} directive, and is 3839terminated by an @code{.endr} directive. For each character in @var{value}, 3840@var{symbol} is set to the character, and the sequence of statements is 3841assembled. If no @var{value} is listed, the sequence of statements is 3842assembled once, with @var{symbol} set to the null string. To refer to 3843@var{symbol} within the sequence of statements, use @var{\symbol}. 3844 3845For example, assembling 3846 3847@example 3848 .irpc param,123 3849 move d\param,sp@@- 3850 .endr 3851@end example 3852 3853is equivalent to assembling 3854 3855@example 3856 move d1,sp@@- 3857 move d2,sp@@- 3858 move d3,sp@@- 3859@end example 3860 3861@node Lcomm 3862@section @code{.lcomm @var{symbol} , @var{length}} 3863 3864@cindex @code{lcomm} directive 3865@cindex local common symbols 3866@cindex symbols, local common 3867Reserve @var{length} (an absolute expression) bytes for a local common 3868denoted by @var{symbol}. The section and value of @var{symbol} are 3869those of the new local common. The addresses are allocated in the bss 3870section, so that at run-time the bytes start off zeroed. @var{Symbol} 3871is not declared global (@pxref{Global,,@code{.global}}), so is normally 3872not visible to @code{@value{LD}}. 3873 3874@ifset GENERIC 3875Some targets permit a third argument to be used with @code{.lcomm}. This 3876argument specifies the desired alignment of the symbol in the bss section. 3877@end ifset 3878 3879@ifset HPPA 3880The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is 3881@samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. 3882@end ifset 3883 3884@node Lflags 3885@section @code{.lflags} 3886 3887@cindex @code{lflags} directive (ignored) 3888@code{@value{AS}} accepts this directive, for compatibility with other 3889assemblers, but ignores it. 3890 3891@ifclear no-line-dir 3892@node Line 3893@section @code{.line @var{line-number}} 3894 3895@cindex @code{line} directive 3896@end ifclear 3897@ifset no-line-dir 3898@node Ln 3899@section @code{.ln @var{line-number}} 3900 3901@cindex @code{ln} directive 3902@end ifset 3903@cindex logical line number 3904@ifset aout-bout 3905Change the logical line number. @var{line-number} must be an absolute 3906expression. The next line has that logical line number. Therefore any other 3907statements on the current line (after a statement separator character) are 3908reported as on logical line number @var{line-number} @minus{} 1. One day 3909@code{@value{AS}} will no longer support this directive: it is recognized only 3910for compatibility with existing assembler programs. 3911 3912@ifset GENERIC 3913@ifset A29K 3914@emph{Warning:} In the AMD29K configuration of @value{AS}, this command is 3915not available; use the synonym @code{.ln} in that context. 3916@end ifset 3917@end ifset 3918@end ifset 3919 3920@ifclear no-line-dir 3921Even though this is a directive associated with the @code{a.out} or 3922@code{b.out} object-code formats, @code{@value{AS}} still recognizes it 3923when producing COFF output, and treats @samp{.line} as though it 3924were the COFF @samp{.ln} @emph{if} it is found outside a 3925@code{.def}/@code{.endef} pair. 3926 3927Inside a @code{.def}, @samp{.line} is, instead, one of the directives 3928used by compilers to generate auxiliary symbol information for 3929debugging. 3930@end ifclear 3931 3932@node Linkonce 3933@section @code{.linkonce [@var{type}]} 3934@cindex COMDAT 3935@cindex @code{linkonce} directive 3936@cindex common sections 3937Mark the current section so that the linker only includes a single copy of it. 3938This may be used to include the same section in several different object files, 3939but ensure that the linker will only include it once in the final output file. 3940The @code{.linkonce} pseudo-op must be used for each instance of the section. 3941Duplicate sections are detected based on the section name, so it should be 3942unique. 3943 3944This directive is only supported by a few object file formats; as of this 3945writing, the only object file format which supports it is the Portable 3946Executable format used on Windows NT. 3947 3948The @var{type} argument is optional. If specified, it must be one of the 3949following strings. For example: 3950@smallexample 3951.linkonce same_size 3952@end smallexample 3953Not all types may be supported on all object file formats. 3954 3955@table @code 3956@item discard 3957Silently discard duplicate sections. This is the default. 3958 3959@item one_only 3960Warn if there are duplicate sections, but still keep only one copy. 3961 3962@item same_size 3963Warn if any of the duplicates have different sizes. 3964 3965@item same_contents 3966Warn if any of the duplicates do not have exactly the same contents. 3967@end table 3968 3969@node Ln 3970@section @code{.ln @var{line-number}} 3971 3972@cindex @code{ln} directive 3973@ifclear no-line-dir 3974@samp{.ln} is a synonym for @samp{.line}. 3975@end ifclear 3976@ifset no-line-dir 3977Tell @code{@value{AS}} to change the logical line number. @var{line-number} 3978must be an absolute expression. The next line has that logical 3979line number, so any other statements on the current line (after a 3980statement separator character @code{;}) are reported as on logical 3981line number @var{line-number} @minus{} 1. 3982@ifset BOUT 3983 3984This directive is accepted, but ignored, when @code{@value{AS}} is 3985configured for @code{b.out}; its effect is only associated with COFF 3986output format. 3987@end ifset 3988@end ifset 3989 3990@node MRI 3991@section @code{.mri @var{val}} 3992 3993@cindex @code{mri} directive 3994@cindex MRI mode, temporarily 3995If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If 3996@var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change 3997affects code assembled until the next @code{.mri} directive, or until the end 3998of the file. @xref{M, MRI mode, MRI mode}. 3999 4000@node List 4001@section @code{.list} 4002 4003@cindex @code{list} directive 4004@cindex listing control, turning on 4005Control (in conjunction with the @code{.nolist} directive) whether or 4006not assembly listings are generated. These two directives maintain an 4007internal counter (which is zero initially). @code{.list} increments the 4008counter, and @code{.nolist} decrements it. Assembly listings are 4009generated whenever the counter is greater than zero. 4010 4011By default, listings are disabled. When you enable them (with the 4012@samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), 4013the initial value of the listing counter is one. 4014 4015@node Long 4016@section @code{.long @var{expressions}} 4017 4018@cindex @code{long} directive 4019@code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}. 4020 4021@ignore 4022@c no one seems to know what this is for or whether this description is 4023@c what it really ought to do 4024@node Lsym 4025@section @code{.lsym @var{symbol}, @var{expression}} 4026 4027@cindex @code{lsym} directive 4028@cindex symbol, not referenced in assembly 4029@code{.lsym} creates a new symbol named @var{symbol}, but does not put it in 4030the hash table, ensuring it cannot be referenced by name during the 4031rest of the assembly. This sets the attributes of the symbol to be 4032the same as the expression value: 4033@smallexample 4034@var{other} = @var{descriptor} = 0 4035@var{type} = @r{(section of @var{expression})} 4036@var{value} = @var{expression} 4037@end smallexample 4038@noindent 4039The new symbol is not flagged as external. 4040@end ignore 4041 4042@node Macro 4043@section @code{.macro} 4044 4045@cindex macros 4046The commands @code{.macro} and @code{.endm} allow you to define macros that 4047generate assembly output. For example, this definition specifies a macro 4048@code{sum} that puts a sequence of numbers into memory: 4049 4050@example 4051 .macro sum from=0, to=5 4052 .long \from 4053 .if \to-\from 4054 sum "(\from+1)",\to 4055 .endif 4056 .endm 4057@end example 4058 4059@noindent 4060With that definition, @samp{SUM 0,5} is equivalent to this assembly input: 4061 4062@example 4063 .long 0 4064 .long 1 4065 .long 2 4066 .long 3 4067 .long 4 4068 .long 5 4069@end example 4070 4071@ftable @code 4072@item .macro @var{macname} 4073@itemx .macro @var{macname} @var{macargs} @dots{} 4074@cindex @code{macro} directive 4075Begin the definition of a macro called @var{macname}. If your macro 4076definition requires arguments, specify their names after the macro name, 4077separated by commas or spaces. You can supply a default value for any 4078macro argument by following the name with @samp{=@var{deflt}}. For 4079example, these are all valid @code{.macro} statements: 4080 4081@table @code 4082@item .macro comm 4083Begin the definition of a macro called @code{comm}, which takes no 4084arguments. 4085 4086@item .macro plus1 p, p1 4087@itemx .macro plus1 p p1 4088Either statement begins the definition of a macro called @code{plus1}, 4089which takes two arguments; within the macro definition, write 4090@samp{\p} or @samp{\p1} to evaluate the arguments. 4091 4092@item .macro reserve_str p1=0 p2 4093Begin the definition of a macro called @code{reserve_str}, with two 4094arguments. The first argument has a default value, but not the second. 4095After the definition is complete, you can call the macro either as 4096@samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to 4097@var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str 4098,@var{b}} (with @samp{\p1} evaluating as the default, in this case 4099@samp{0}, and @samp{\p2} evaluating to @var{b}). 4100@end table 4101 4102When you call a macro, you can specify the argument values either by 4103position, or by keyword. For example, @samp{sum 9,17} is equivalent to 4104@samp{sum to=17, from=9}. 4105 4106@item .endm 4107@cindex @code{endm} directive 4108Mark the end of a macro definition. 4109 4110@item .exitm 4111@cindex @code{exitm} directive 4112Exit early from the current macro definition. 4113 4114@cindex number of macros executed 4115@cindex macros, count executed 4116@item \@@ 4117@code{@value{AS}} maintains a counter of how many macros it has 4118executed in this pseudo-variable; you can copy that number to your 4119output with @samp{\@@}, but @emph{only within a macro definition}. 4120 4121@ignore 4122@item LOCAL @var{name} [ , @dots{} ] 4123@emph{Warning: @code{LOCAL} is only available if you select ``alternate 4124macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,, 4125Alternate macro syntax}. 4126 4127Generate a string replacement for each of the @var{name} arguments, and 4128replace any instances of @var{name} in each macro expansion. The 4129replacement string is unique in the assembly, and different for each 4130separate macro expansion. @code{LOCAL} allows you to write macros that 4131define symbols, without fear of conflict between separate macro expansions. 4132@end ignore 4133@end ftable 4134 4135@node Nolist 4136@section @code{.nolist} 4137 4138@cindex @code{nolist} directive 4139@cindex listing control, turning off 4140Control (in conjunction with the @code{.list} directive) whether or 4141not assembly listings are generated. These two directives maintain an 4142internal counter (which is zero initially). @code{.list} increments the 4143counter, and @code{.nolist} decrements it. Assembly listings are 4144generated whenever the counter is greater than zero. 4145 4146@node Octa 4147@section @code{.octa @var{bignums}} 4148 4149@c FIXME: double size emitted for "octa" on i960, others? Or warn? 4150@cindex @code{octa} directive 4151@cindex integer, 16-byte 4152@cindex sixteen byte integer 4153This directive expects zero or more bignums, separated by commas. For each 4154bignum, it emits a 16-byte integer. 4155 4156The term ``octa'' comes from contexts in which a ``word'' is two bytes; 4157hence @emph{octa}-word for 16 bytes. 4158 4159@node Org 4160@section @code{.org @var{new-lc} , @var{fill}} 4161 4162@cindex @code{org} directive 4163@cindex location counter, advancing 4164@cindex advancing location counter 4165@cindex current address, advancing 4166Advance the location counter of the current section to 4167@var{new-lc}. @var{new-lc} is either an absolute expression or an 4168expression with the same section as the current subsection. That is, 4169you can't use @code{.org} to cross sections: if @var{new-lc} has the 4170wrong section, the @code{.org} directive is ignored. To be compatible 4171with former assemblers, if the section of @var{new-lc} is absolute, 4172@code{@value{AS}} issues a warning, then pretends the section of @var{new-lc} 4173is the same as the current subsection. 4174 4175@code{.org} may only increase the location counter, or leave it 4176unchanged; you cannot use @code{.org} to move the location counter 4177backwards. 4178 4179@c double negative used below "not undefined" because this is a specific 4180@c reference to "undefined" (as SEG_UNKNOWN is called in this manual) 4181@c section. doc@cygnus.com 18feb91 4182Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc} 4183may not be undefined. If you really detest this restriction we eagerly await 4184a chance to share your improved assembler. 4185 4186Beware that the origin is relative to the start of the section, not 4187to the start of the subsection. This is compatible with other 4188people's assemblers. 4189 4190When the location counter (of the current subsection) is advanced, the 4191intervening bytes are filled with @var{fill} which should be an 4192absolute expression. If the comma and @var{fill} are omitted, 4193@var{fill} defaults to zero. 4194 4195@node P2align 4196@section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} 4197 4198@cindex padding the location counter given a power of two 4199@cindex @code{p2align} directive 4200Pad the location counter (in the current subsection) to a particular 4201storage boundary. The first expression (which must be absolute) is the 4202number of low-order zero bits the location counter must have after 4203advancement. For example @samp{.p2align 3} advances the location 4204counter until it a multiple of 8. If the location counter is already a 4205multiple of 8, no change is needed. 4206 4207The second expression (also absolute) gives the fill value to be stored in the 4208padding bytes. It (and the comma) may be omitted. If it is omitted, the 4209padding bytes are normally zero. However, on some systems, if the section is 4210marked as containing code and the fill value is omitted, the space is filled 4211with no-op instructions. 4212 4213The third expression is also absolute, and is also optional. If it is present, 4214it is the maximum number of bytes that should be skipped by this alignment 4215directive. If doing the alignment would require skipping more bytes than the 4216specified maximum, then the alignment is not done at all. You can omit the 4217fill value (the second argument) entirely by simply using two commas after the 4218required alignment; this can be useful if you want the alignment to be filled 4219with no-op instructions when appropriate. 4220 4221@cindex @code{p2alignw} directive 4222@cindex @code{p2alignl} directive 4223The @code{.p2alignw} and @code{.p2alignl} directives are variants of the 4224@code{.p2align} directive. The @code{.p2alignw} directive treats the fill 4225pattern as a two byte word value. The @code{.p2alignl} directives treats the 4226fill pattern as a four byte longword value. For example, @code{.p2alignw 42272,0x368d} will align to a multiple of 4. If it skips two bytes, they will be 4228filled in with the value 0x368d (the exact placement of the bytes depends upon 4229the endianness of the processor). If it skips 1 or 3 bytes, the fill value is 4230undefined. 4231 4232@node Print 4233@section @code{.print @var{string}} 4234 4235@cindex @code{print} directive 4236@code{@value{AS}} will print @var{string} on the standard output during 4237assembly. You must put @var{string} in double quotes. 4238 4239@node Psize 4240@section @code{.psize @var{lines} , @var{columns}} 4241 4242@cindex @code{psize} directive 4243@cindex listing control: paper size 4244@cindex paper size, for listings 4245Use this directive to declare the number of lines---and, optionally, the 4246number of columns---to use for each page, when generating listings. 4247 4248If you do not use @code{.psize}, listings use a default line-count 4249of 60. You may omit the comma and @var{columns} specification; the 4250default width is 200 columns. 4251 4252@code{@value{AS}} generates formfeeds whenever the specified number of 4253lines is exceeded (or whenever you explicitly request one, using 4254@code{.eject}). 4255 4256If you specify @var{lines} as @code{0}, no formfeeds are generated save 4257those explicitly specified with @code{.eject}. 4258 4259@node Purgem 4260@section @code{.purgem @var{name}} 4261 4262@cindex @code{purgem} directive 4263Undefine the macro @var{name}, so that later uses of the string will not be 4264expanded. @xref{Macro}. 4265 4266@node Quad 4267@section @code{.quad @var{bignums}} 4268 4269@cindex @code{quad} directive 4270@code{.quad} expects zero or more bignums, separated by commas. For 4271each bignum, it emits 4272@ifclear bignum-16 4273an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a 4274warning message; and just takes the lowest order 8 bytes of the bignum. 4275@cindex eight-byte integer 4276@cindex integer, 8-byte 4277 4278The term ``quad'' comes from contexts in which a ``word'' is two bytes; 4279hence @emph{quad}-word for 8 bytes. 4280@end ifclear 4281@ifset bignum-16 4282a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a 4283warning message; and just takes the lowest order 16 bytes of the bignum. 4284@cindex sixteen-byte integer 4285@cindex integer, 16-byte 4286@end ifset 4287 4288@node Rept 4289@section @code{.rept @var{count}} 4290 4291@cindex @code{rept} directive 4292Repeat the sequence of lines between the @code{.rept} directive and the next 4293@code{.endr} directive @var{count} times. 4294 4295For example, assembling 4296 4297@example 4298 .rept 3 4299 .long 0 4300 .endr 4301@end example 4302 4303is equivalent to assembling 4304 4305@example 4306 .long 0 4307 .long 0 4308 .long 0 4309@end example 4310 4311@node Sbttl 4312@section @code{.sbttl "@var{subheading}"} 4313 4314@cindex @code{sbttl} directive 4315@cindex subtitles for listings 4316@cindex listing control: subtitle 4317Use @var{subheading} as the title (third line, immediately after the 4318title line) when generating assembly listings. 4319 4320This directive affects subsequent pages, as well as the current page if 4321it appears within ten lines of the top of a page. 4322 4323@ifset COFF 4324@node Scl 4325@section @code{.scl @var{class}} 4326 4327@cindex @code{scl} directive 4328@cindex symbol storage class (COFF) 4329@cindex COFF symbol storage class 4330Set the storage-class value for a symbol. This directive may only be 4331used inside a @code{.def}/@code{.endef} pair. Storage class may flag 4332whether a symbol is static or external, or it may record further 4333symbolic debugging information. 4334@ifset BOUT 4335 4336The @samp{.scl} directive is primarily associated with COFF output; when 4337configured to generate @code{b.out} output format, @code{@value{AS}} 4338accepts this directive but ignores it. 4339@end ifset 4340@end ifset 4341 4342@node Section 4343@section @code{.section @var{name}} 4344 4345@cindex @code{section} directive 4346@cindex named section 4347Use the @code{.section} directive to assemble the following code into a section 4348named @var{name}. 4349 4350This directive is only supported for targets that actually support arbitrarily 4351named sections; on @code{a.out} targets, for example, it is not accepted, even 4352with a standard @code{a.out} section name. 4353 4354@ifset COFF 4355For COFF targets, the @code{.section} directive is used in one of the following 4356ways: 4357@smallexample 4358.section @var{name}[, "@var{flags}"] 4359.section @var{name}[, @var{subsegment}] 4360@end smallexample 4361 4362If the optional argument is quoted, it is taken as flags to use for the 4363section. Each flag is a single character. The following flags are recognized: 4364@table @code 4365@item b 4366bss section (uninitialized data) 4367@item n 4368section is not loaded 4369@item w 4370writable section 4371@item d 4372data section 4373@item r 4374read-only section 4375@item x 4376executable section 4377@item s 4378shared section (meaningful for PE targets) 4379@end table 4380 4381If no flags are specified, the default flags depend upon the section name. If 4382the section name is not recognized, the default will be for the section to be 4383loaded and writable. 4384 4385If the optional argument to the @code{.section} directive is not quoted, it is 4386taken as a subsegment number (@pxref{Sub-Sections}). 4387@end ifset 4388 4389@ifset ELF 4390For ELF targets, the @code{.section} directive is used like this: 4391@smallexample 4392.section @var{name}[, "@var{flags}"[, @@@var{type}]] 4393@end smallexample 4394The optional @var{flags} argument is a quoted string which may contain any 4395combintion of the following characters: 4396@table @code 4397@item a 4398section is allocatable 4399@item w 4400section is writable 4401@item x 4402section is executable 4403@end table 4404 4405The optional @var{type} argument may contain one of the following constants: 4406@table @code 4407@item @@progbits 4408section contains data 4409@item @@nobits 4410section does not contain data (i.e., section only occupies space) 4411@end table 4412 4413If no flags are specified, the default flags depend upon the section name. If 4414the section name is not recognized, the default will be for the section to have 4415none of the above flags: it will not be allocated in memory, nor writable, nor 4416executable. The section will contain data. 4417 4418For ELF targets, the assembler supports another type of @code{.section} 4419directive for compatibility with the Solaris assembler: 4420@smallexample 4421.section "@var{name}"[, @var{flags}...] 4422@end smallexample 4423Note that the section name is quoted. There may be a sequence of comma 4424separated flags: 4425@table @code 4426@item #alloc 4427section is allocatable 4428@item #write 4429section is writable 4430@item #execinstr 4431section is executable 4432@end table 4433@end ifset 4434 4435@node Set 4436@section @code{.set @var{symbol}, @var{expression}} 4437 4438@cindex @code{set} directive 4439@cindex symbol value, setting 4440Set the value of @var{symbol} to @var{expression}. This 4441changes @var{symbol}'s value and type to conform to 4442@var{expression}. If @var{symbol} was flagged as external, it remains 4443flagged (@pxref{Symbol Attributes}). 4444 4445You may @code{.set} a symbol many times in the same assembly. 4446 4447If you @code{.set} a global symbol, the value stored in the object 4448file is the last value stored into it. 4449 4450@ifset HPPA 4451The syntax for @code{set} on the HPPA is 4452@samp{@var{symbol} .set @var{expression}}. 4453@end ifset 4454 4455@node Short 4456@section @code{.short @var{expressions}} 4457 4458@cindex @code{short} directive 4459@ifset GENERIC 4460@code{.short} is normally the same as @samp{.word}. 4461@xref{Word,,@code{.word}}. 4462 4463In some configurations, however, @code{.short} and @code{.word} generate 4464numbers of different lengths; @pxref{Machine Dependencies}. 4465@end ifset 4466@ifclear GENERIC 4467@ifset W16 4468@code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. 4469@end ifset 4470@ifset W32 4471This expects zero or more @var{expressions}, and emits 4472a 16 bit number for each. 4473@end ifset 4474@end ifclear 4475 4476@node Single 4477@section @code{.single @var{flonums}} 4478 4479@cindex @code{single} directive 4480@cindex floating point numbers (single) 4481This directive assembles zero or more flonums, separated by commas. It 4482has the same effect as @code{.float}. 4483@ifset GENERIC 4484The exact kind of floating point numbers emitted depends on how 4485@code{@value{AS}} is configured. @xref{Machine Dependencies}. 4486@end ifset 4487@ifclear GENERIC 4488@ifset IEEEFLOAT 4489On the @value{TARGET} family, @code{.single} emits 32-bit floating point 4490numbers in @sc{ieee} format. 4491@end ifset 4492@end ifclear 4493 4494@ifset COFF 4495@node Size 4496@section @code{.size} 4497 4498@cindex @code{size} directive 4499This directive is generated by compilers to include auxiliary debugging 4500information in the symbol table. It is only permitted inside 4501@code{.def}/@code{.endef} pairs. 4502@ifset BOUT 4503 4504@samp{.size} is only meaningful when generating COFF format output; when 4505@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 4506ignores it. 4507@end ifset 4508@end ifset 4509 4510@node Sleb128 4511@section @code{.sleb128 @var{expressions}} 4512 4513@cindex @code{sleb128} directive 4514@var{sleb128} stands for ``signed little endian base 128.'' This is a 4515compact, variable length representation of numbers used by the DWARF 4516symbolic debugging format. @xref{Uleb128,@code{.uleb128}}. 4517 4518@ifclear no-space-dir 4519@node Skip 4520@section @code{.skip @var{size} , @var{fill}} 4521 4522@cindex @code{skip} directive 4523@cindex filling memory 4524This directive emits @var{size} bytes, each of value @var{fill}. Both 4525@var{size} and @var{fill} are absolute expressions. If the comma and 4526@var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as 4527@samp{.space}. 4528 4529@node Space 4530@section @code{.space @var{size} , @var{fill}} 4531 4532@cindex @code{space} directive 4533@cindex filling memory 4534This directive emits @var{size} bytes, each of value @var{fill}. Both 4535@var{size} and @var{fill} are absolute expressions. If the comma 4536and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same 4537as @samp{.skip}. 4538 4539@ifset HPPA 4540@quotation 4541@emph{Warning:} @code{.space} has a completely different meaning for HPPA 4542targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 4543Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the 4544@code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, 4545for a summary. 4546@end quotation 4547@end ifset 4548@end ifclear 4549 4550@ifset A29K 4551@ifclear GENERIC 4552@node Space 4553@section @code{.space} 4554@cindex @code{space} directive 4555@end ifclear 4556On the AMD 29K, this directive is ignored; it is accepted for 4557compatibility with other AMD 29K assemblers. 4558 4559@quotation 4560@emph{Warning:} In most versions of the @sc{gnu} assembler, the directive 4561@code{.space} has the effect of @code{.block} @xref{Machine Dependencies}. 4562@end quotation 4563@end ifset 4564 4565@ifset have-stabs 4566@node Stab 4567@section @code{.stabd, .stabn, .stabs} 4568 4569@cindex symbolic debuggers, information for 4570@cindex @code{stab@var{x}} directives 4571There are three directives that begin @samp{.stab}. 4572All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. 4573The symbols are not entered in the @code{@value{AS}} hash table: they 4574cannot be referenced elsewhere in the source file. 4575Up to five fields are required: 4576 4577@table @var 4578@item string 4579This is the symbol's name. It may contain any character except 4580@samp{\000}, so is more general than ordinary symbol names. Some 4581debuggers used to code arbitrarily complex structures into symbol names 4582using this field. 4583 4584@item type 4585An absolute expression. The symbol's type is set to the low 8 bits of 4586this expression. Any bit pattern is permitted, but @code{@value{LD}} 4587and debuggers choke on silly bit patterns. 4588 4589@item other 4590An absolute expression. The symbol's ``other'' attribute is set to the 4591low 8 bits of this expression. 4592 4593@item desc 4594An absolute expression. The symbol's descriptor is set to the low 16 4595bits of this expression. 4596 4597@item value 4598An absolute expression which becomes the symbol's value. 4599@end table 4600 4601If a warning is detected while reading a @code{.stabd}, @code{.stabn}, 4602or @code{.stabs} statement, the symbol has probably already been created; 4603you get a half-formed symbol in your object file. This is 4604compatible with earlier assemblers! 4605 4606@table @code 4607@cindex @code{stabd} directive 4608@item .stabd @var{type} , @var{other} , @var{desc} 4609 4610The ``name'' of the symbol generated is not even an empty string. 4611It is a null pointer, for compatibility. Older assemblers used a 4612null pointer so they didn't waste space in object files with empty 4613strings. 4614 4615The symbol's value is set to the location counter, 4616relocatably. When your program is linked, the value of this symbol 4617is the address of the location counter when the @code{.stabd} was 4618assembled. 4619 4620@cindex @code{stabn} directive 4621@item .stabn @var{type} , @var{other} , @var{desc} , @var{value} 4622The name of the symbol is set to the empty string @code{""}. 4623 4624@cindex @code{stabs} directive 4625@item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} 4626All five fields are specified. 4627@end table 4628@end ifset 4629@c end have-stabs 4630 4631@node String 4632@section @code{.string} "@var{str}" 4633 4634@cindex string, copying to object file 4635@cindex @code{string} directive 4636 4637Copy the characters in @var{str} to the object file. You may specify more than 4638one string to copy, separated by commas. Unless otherwise specified for a 4639particular machine, the assembler marks the end of each string with a 0 byte. 4640You can use any of the escape sequences described in @ref{Strings,,Strings}. 4641 4642@node Struct 4643@section @code{.struct @var{expression}} 4644 4645@cindex @code{struct} directive 4646Switch to the absolute section, and set the section offset to @var{expression}, 4647which must be an absolute expression. You might use this as follows: 4648@smallexample 4649 .struct 0 4650field1: 4651 .struct field1 + 4 4652field2: 4653 .struct field2 + 4 4654field3: 4655@end smallexample 4656This would define the symbol @code{field1} to have the value 0, the symbol 4657@code{field2} to have the value 4, and the symbol @code{field3} to have the 4658value 8. Assembly would be left in the absolute section, and you would need to 4659use a @code{.section} directive of some sort to change to some other section 4660before further assembly. 4661 4662@ifset ELF 4663@node Symver 4664@section @code{.symver} 4665@cindex @code{symver} directive 4666@cindex symbol versioning 4667@cindex versions of symbols 4668Use the @code{.symver} directive to bind symbols to specific version nodes 4669within a source file. This is only supported on ELF platforms, and is 4670typically used when assembling files to be linked into a shared library. 4671There are cases where it may make sense to use this in objects to be bound 4672into an application itself so as to override a versioned symbol from a 4673shared library. 4674 4675For ELF targets, the @code{.symver} directive is used like this: 4676@smallexample 4677.symver @var{name}, @var{name2@@nodename} 4678@end smallexample 4679In this case, the symbol @var{name} must exist and be defined within the file 4680being assembled. The @code{.versym} directive effectively creates a symbol 4681alias with the name @var{name2@@nodename}, and in fact the main reason that we 4682just don't try and create a regular alias is that the @var{@@} character isn't 4683permitted in symbol names. The @var{name2} part of the name is the actual name 4684of the symbol by which it will be externally referenced. The name @var{name} 4685itself is merely a name of convenience that is used so that it is possible to 4686have definitions for multiple versions of a function within a single source 4687file, and so that the compiler can unambiguously know which version of a 4688function is being mentioned. The @var{nodename} portion of the alias should be 4689the name of a node specified in the version script supplied to the linker when 4690building a shared library. If you are attempting to override a versioned 4691symbol from a shared library, then @var{nodename} should correspond to the 4692nodename of the symbol you are trying to override. 4693@end ifset 4694 4695@ifset COFF 4696@node Tag 4697@section @code{.tag @var{structname}} 4698 4699@cindex COFF structure debugging 4700@cindex structure debugging, COFF 4701@cindex @code{tag} directive 4702This directive is generated by compilers to include auxiliary debugging 4703information in the symbol table. It is only permitted inside 4704@code{.def}/@code{.endef} pairs. Tags are used to link structure 4705definitions in the symbol table with instances of those structures. 4706@ifset BOUT 4707 4708@samp{.tag} is only used when generating COFF format output; when 4709@code{@value{AS}} is generating @code{b.out}, it accepts this directive but 4710ignores it. 4711@end ifset 4712@end ifset 4713 4714@node Text 4715@section @code{.text @var{subsection}} 4716 4717@cindex @code{text} directive 4718Tells @code{@value{AS}} to assemble the following statements onto the end of 4719the text subsection numbered @var{subsection}, which is an absolute 4720expression. If @var{subsection} is omitted, subsection number zero 4721is used. 4722 4723@node Title 4724@section @code{.title "@var{heading}"} 4725 4726@cindex @code{title} directive 4727@cindex listing control: title line 4728Use @var{heading} as the title (second line, immediately after the 4729source file name and pagenumber) when generating assembly listings. 4730 4731This directive affects subsequent pages, as well as the current page if 4732it appears within ten lines of the top of a page. 4733 4734@ifset COFF 4735@node Type 4736@section @code{.type @var{int}} 4737 4738@cindex COFF symbol type 4739@cindex symbol type, COFF 4740@cindex @code{type} directive 4741This directive, permitted only within @code{.def}/@code{.endef} pairs, 4742records the integer @var{int} as the type attribute of a symbol table entry. 4743@ifset BOUT 4744 4745@samp{.type} is associated only with COFF format output; when 4746@code{@value{AS}} is configured for @code{b.out} output, it accepts this 4747directive but ignores it. 4748@end ifset 4749@end ifset 4750 4751@ifset COFF 4752@node Val 4753@section @code{.val @var{addr}} 4754 4755@cindex @code{val} directive 4756@cindex COFF value attribute 4757@cindex value attribute, COFF 4758This directive, permitted only within @code{.def}/@code{.endef} pairs, 4759records the address @var{addr} as the value attribute of a symbol table 4760entry. 4761@ifset BOUT 4762 4763@samp{.val} is used only for COFF output; when @code{@value{AS}} is 4764configured for @code{b.out}, it accepts this directive but ignores it. 4765@end ifset 4766@end ifset 4767 4768@node Uleb128 4769@section @code{.uleb128 @var{expressions}} 4770 4771@cindex @code{uleb128} directive 4772@var{uleb128} stands for ``unsigned little endian base 128.'' This is a 4773compact, variable length representation of numbers used by the DWARF 4774symbolic debugging format. @xref{Sleb128,@code{.sleb128}}. 4775 4776@ifset ELF 4777@node Visibility 4778@section @code{.internal}, @code{.hidden}, @code{.protected} 4779@cindex @code{internal} directive 4780@cindex @code{hidden} directive 4781@cindex @code{protected} directive 4782@cindex symbol visibility 4783 4784These directives can be used to set the visibility of a specified symbol. By 4785default a symbol's visibility is set by its binding (local, global or weak), 4786but these directives can be used to override that. 4787 4788A visibility of @code{protected} means that any references to the symbol from 4789within the component that defines the symbol must be resolved to the definition 4790in that component, even if a definition in another component would normally 4791preempt this. 4792 4793A visibility of @code{hidden} means that the symbol is not visible to other 4794components. Such a symbol is always considered to be protected as well. 4795 4796A visibility of @code{internal} is the same as a visibility of @code{hidden}, 4797except that some extra, processor specific processing must also be performed 4798upon the symbol. 4799 4800For ELF targets, the directives are used like this: 4801 4802@smallexample 4803.internal @var{name} 4804.hidden @var{name} 4805.protected @var{name} 4806@end smallexample 4807 4808@end ifset 4809 4810@node Word 4811@section @code{.word @var{expressions}} 4812 4813@cindex @code{word} directive 4814This directive expects zero or more @var{expressions}, of any section, 4815separated by commas. 4816@ifclear GENERIC 4817@ifset W32 4818For each expression, @code{@value{AS}} emits a 32-bit number. 4819@end ifset 4820@ifset W16 4821For each expression, @code{@value{AS}} emits a 16-bit number. 4822@end ifset 4823@end ifclear 4824@ifset GENERIC 4825 4826The size of the number emitted, and its byte order, 4827depend on what target computer the assembly is for. 4828@end ifset 4829 4830@c on amd29k, i960, sparc the "special treatment to support compilers" doesn't 4831@c happen---32-bit addressability, period; no long/short jumps. 4832@ifset DIFF-TBL-KLUGE 4833@cindex difference tables altered 4834@cindex altered difference tables 4835@quotation 4836@emph{Warning: Special Treatment to support Compilers} 4837@end quotation 4838 4839@ifset GENERIC 4840Machines with a 32-bit address space, but that do less than 32-bit 4841addressing, require the following special treatment. If the machine of 4842interest to you does 32-bit addressing (or doesn't require it; 4843@pxref{Machine Dependencies}), you can ignore this issue. 4844 4845@end ifset 4846In order to assemble compiler output into something that works, 4847@code{@value{AS}} occasionlly does strange things to @samp{.word} directives. 4848Directives of the form @samp{.word sym1-sym2} are often emitted by 4849compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a 4850directive of the form @samp{.word sym1-sym2}, and the difference between 4851@code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}} 4852creates a @dfn{secondary jump table}, immediately before the next label. 4853This secondary jump table is preceded by a short-jump to the 4854first byte after the secondary table. This short-jump prevents the flow 4855of control from accidentally falling into the new table. Inside the 4856table is a long-jump to @code{sym2}. The original @samp{.word} 4857contains @code{sym1} minus the address of the long-jump to 4858@code{sym2}. 4859 4860If there were several occurrences of @samp{.word sym1-sym2} before the 4861secondary jump table, all of them are adjusted. If there was a 4862@samp{.word sym3-sym4}, that also did not fit in sixteen bits, a 4863long-jump to @code{sym4} is included in the secondary jump table, 4864and the @code{.word} directives are adjusted to contain @code{sym3} 4865minus the address of the long-jump to @code{sym4}; and so on, for as many 4866entries in the original jump table as necessary. 4867 4868@ifset INTERNALS 4869@emph{This feature may be disabled by compiling @code{@value{AS}} with the 4870@samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse 4871assembly language programmers. 4872@end ifset 4873@end ifset 4874@c end DIFF-TBL-KLUGE 4875 4876@node Deprecated 4877@section Deprecated Directives 4878 4879@cindex deprecated directives 4880@cindex obsolescent directives 4881One day these directives won't work. 4882They are included for compatibility with older assemblers. 4883@table @t 4884@item .abort 4885@item .line 4886@end table 4887 4888@ifset GENERIC 4889@node Machine Dependencies 4890@chapter Machine Dependent Features 4891 4892@cindex machine dependencies 4893The machine instruction sets are (almost by definition) different on 4894each machine where @code{@value{AS}} runs. Floating point representations 4895vary as well, and @code{@value{AS}} often supports a few additional 4896directives or command-line options for compatibility with other 4897assemblers on a particular platform. Finally, some versions of 4898@code{@value{AS}} support special pseudo-instructions for branch 4899optimization. 4900 4901This chapter discusses most of these differences, though it does not 4902include details on any machine's instruction set. For details on that 4903subject, see the hardware manufacturer's manual. 4904 4905@menu 4906@ifset A29K 4907* AMD29K-Dependent:: AMD 29K Dependent Features 4908@end ifset 4909@ifset ARC 4910* ARC-Dependent:: ARC Dependent Features 4911@end ifset 4912@ifset ARM 4913* ARM-Dependent:: ARM Dependent Features 4914@end ifset 4915@ifset D10V 4916* D10V-Dependent:: D10V Dependent Features 4917@end ifset 4918@ifset D30V 4919* D30V-Dependent:: D30V Dependent Features 4920@end ifset 4921@ifset H8/300 4922* H8/300-Dependent:: Hitachi H8/300 Dependent Features 4923@end ifset 4924@ifset H8/500 4925* H8/500-Dependent:: Hitachi H8/500 Dependent Features 4926@end ifset 4927@ifset HPPA 4928* HPPA-Dependent:: HPPA Dependent Features 4929@end ifset 4930@ifset I370 4931* ESA/390-Dependent:: IBM ESA/390 Dependent Features 4932@end ifset 4933@ifset I80386 4934* i386-Dependent:: Intel 80386 Dependent Features 4935@end ifset 4936@ifset I960 4937* i960-Dependent:: Intel 80960 Dependent Features 4938@end ifset 4939@ifset M680X0 4940* M68K-Dependent:: M680x0 Dependent Features 4941@end ifset 4942@ifset MIPS 4943* MIPS-Dependent:: MIPS Dependent Features 4944@end ifset 4945@ifset SH 4946* SH-Dependent:: Hitachi SH Dependent Features 4947@end ifset 4948@ifset PJ 4949* PJ-Dependent:: picoJava Dependent Features 4950@end ifset 4951@ifset SPARC 4952* Sparc-Dependent:: SPARC Dependent Features 4953@end ifset 4954@ifset V850 4955* V850-Dependent:: V850 Dependent Features 4956@end ifset 4957@ifset Z8000 4958* Z8000-Dependent:: Z8000 Dependent Features 4959@end ifset 4960@ifset VAX 4961* Vax-Dependent:: VAX Dependent Features 4962@end ifset 4963@end menu 4964 4965@lowersections 4966@end ifset 4967 4968@c The following major nodes are *sections* in the GENERIC version, *chapters* 4969@c in single-cpu versions. This is mainly achieved by @lowersections. There is a 4970@c peculiarity: to preserve cross-references, there must be a node called 4971@c "Machine Dependencies". Hence the conditional nodenames in each 4972@c major node below. Node defaulting in makeinfo requires adjacency of 4973@c node and sectioning commands; hence the repetition of @chapter BLAH 4974@c in both conditional blocks. 4975 4976@ifset ARC 4977@ifset GENERIC 4978@page 4979@node ARC-Dependent 4980@chapter ARC Dependent Features 4981@end ifset 4982@ifclear GENERIC 4983@node Machine Dependencies 4984@chapter ARC Dependent Features 4985@end ifclear 4986 4987@cindex ARC support 4988@menu 4989* ARC-Opts:: Options 4990* ARC-Float:: Floating Point 4991* ARC-Directives:: Sparc Machine Directives 4992@end menu 4993 4994@node ARC-Opts 4995@section Options 4996 4997@cindex options for ARC 4998@cindex ARC options 4999@cindex architectures, ARC 5000@cindex ARC architectures 5001The ARC chip family includes several successive levels (or other 5002variants) of chip, using the same core instruction set, but including 5003a few additional instructions at each level. 5004 5005By default, @code{@value{AS}} assumes the core instruction set (ARC 5006base). The @code{.cpu} pseudo-op is intended to be used to select 5007the variant. 5008 5009@table @code 5010@cindex @code{-mbig-endian} option (ARC) 5011@cindex @code{-mlittle-endian} option (ARC) 5012@cindex ARC big-endian output 5013@cindex ARC little-endian output 5014@cindex big-endian output, ARC 5015@cindex little-endian output, ARC 5016@item -mbig-endian 5017@itemx -mlittle-endian 5018Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or 5019little-endian output at run time (unlike most other @sc{gnu} development 5020tools, which must be configured for one or the other). Use 5021@samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian} 5022for little-endian. 5023@end table 5024 5025@node ARC-Float 5026@section Floating Point 5027 5028@cindex floating point, ARC (@sc{ieee}) 5029@cindex ARC floating point (@sc{ieee}) 5030The ARC cpu family currently does not have hardware floating point 5031support. Software floating point support is provided by @code{GCC} 5032and uses @sc{ieee} floating-point numbers. 5033 5034@node ARC-Directives 5035@section ARC Machine Directives 5036 5037@cindex ARC machine directives 5038@cindex machine directives, ARC 5039The ARC version of @code{@value{AS}} supports the following additional 5040machine directives: 5041 5042@table @code 5043@item .cpu 5044@cindex @code{cpu} directive, SPARC 5045This must be followed by the desired cpu. 5046The ARC is intended to be customizable, @code{.cpu} is used to 5047select the desired variant [though currently there are none]. 5048 5049@end table 5050 5051@end ifset 5052 5053@ifset A29K 5054@include c-a29k.texi 5055@end ifset 5056 5057@ifset ARM 5058@include c-arm.texi 5059@end ifset 5060 5061@ifset Hitachi-all 5062@ifclear GENERIC 5063@node Machine Dependencies 5064@chapter Machine Dependent Features 5065 5066The machine instruction sets are different on each Hitachi chip family, 5067and there are also some syntax differences among the families. This 5068chapter describes the specific @code{@value{AS}} features for each 5069family. 5070 5071@menu 5072* H8/300-Dependent:: Hitachi H8/300 Dependent Features 5073* H8/500-Dependent:: Hitachi H8/500 Dependent Features 5074* SH-Dependent:: Hitachi SH Dependent Features 5075@end menu 5076@lowersections 5077@end ifclear 5078@end ifset 5079 5080@ifset D10V 5081@include c-d10v.texi 5082@end ifset 5083 5084@ifset D30V 5085@include c-d30v.texi 5086@end ifset 5087 5088@ifset H8/300 5089@include c-h8300.texi 5090@end ifset 5091 5092@ifset H8/500 5093@include c-h8500.texi 5094@end ifset 5095 5096@ifset HPPA 5097@include c-hppa.texi 5098@end ifset 5099 5100@ifset I370 5101@include c-i370.texi 5102@end ifset 5103 5104@ifset I80386 5105@include c-i386.texi 5106@end ifset 5107 5108@ifset I960 5109@include c-i960.texi 5110@end ifset 5111 5112 5113@ifset M680X0 5114@include c-m68k.texi 5115@end ifset 5116 5117@ifset MIPS 5118@include c-mips.texi 5119@end ifset 5120 5121@ifset NS32K 5122@include c-ns32k.texi 5123@end ifset 5124 5125@ifset PJ 5126@include c-pj.texi 5127@end ifset 5128 5129@ifset SH 5130@include c-sh.texi 5131@end ifset 5132 5133@ifset SPARC 5134@include c-sparc.texi 5135@end ifset 5136 5137@ifset Z8000 5138@include c-z8k.texi 5139@end ifset 5140 5141@ifset VAX 5142@include c-vax.texi 5143@end ifset 5144 5145@ifset V850 5146@include c-v850.texi 5147@end ifset 5148 5149@ifset GENERIC 5150@c reverse effect of @down at top of generic Machine-Dep chapter 5151@raisesections 5152@end ifset 5153 5154@node Reporting Bugs 5155@chapter Reporting Bugs 5156@cindex bugs in assembler 5157@cindex reporting bugs in assembler 5158 5159Your bug reports play an essential role in making @code{@value{AS}} reliable. 5160 5161Reporting a bug may help you by bringing a solution to your problem, or it may 5162not. But in any case the principal function of a bug report is to help the 5163entire community by making the next version of @code{@value{AS}} work better. 5164Bug reports are your contribution to the maintenance of @code{@value{AS}}. 5165 5166In order for a bug report to serve its purpose, you must include the 5167information that enables us to fix the bug. 5168 5169@menu 5170* Bug Criteria:: Have you found a bug? 5171* Bug Reporting:: How to report bugs 5172@end menu 5173 5174@node Bug Criteria 5175@section Have you found a bug? 5176@cindex bug criteria 5177 5178If you are not sure whether you have found a bug, here are some guidelines: 5179 5180@itemize @bullet 5181@cindex fatal signal 5182@cindex assembler crash 5183@cindex crash of assembler 5184@item 5185If the assembler gets a fatal signal, for any input whatever, that is a 5186@code{@value{AS}} bug. Reliable assemblers never crash. 5187 5188@cindex error on valid input 5189@item 5190If @code{@value{AS}} produces an error message for valid input, that is a bug. 5191 5192@cindex invalid input 5193@item 5194If @code{@value{AS}} does not produce an error message for invalid input, that 5195is a bug. However, you should note that your idea of ``invalid input'' might 5196be our idea of ``an extension'' or ``support for traditional practice''. 5197 5198@item 5199If you are an experienced user of assemblers, your suggestions for improvement 5200of @code{@value{AS}} are welcome in any case. 5201@end itemize 5202 5203@node Bug Reporting 5204@section How to report bugs 5205@cindex bug reports 5206@cindex assembler bugs, reporting 5207 5208A number of companies and individuals offer support for @sc{gnu} products. If 5209you obtained @code{@value{AS}} from a support organization, we recommend you 5210contact that organization first. 5211 5212You can find contact information for many support companies and 5213individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs 5214distribution. 5215 5216In any event, we also recommend that you send bug reports for @code{@value{AS}} 5217to @samp{bug-gnu-utils@@gnu.org}. 5218 5219The fundamental principle of reporting bugs usefully is this: 5220@strong{report all the facts}. If you are not sure whether to state a 5221fact or leave it out, state it! 5222 5223Often people omit facts because they think they know what causes the problem 5224and assume that some details do not matter. Thus, you might assume that the 5225name of a symbol you use in an example does not matter. Well, probably it does 5226not, but one cannot be sure. Perhaps the bug is a stray memory reference which 5227happens to fetch from the location where that name is stored in memory; 5228perhaps, if the name were different, the contents of that location would fool 5229the assembler into doing the right thing despite the bug. Play it safe and 5230give a specific, complete example. That is the easiest thing for you to do, 5231and the most helpful. 5232 5233Keep in mind that the purpose of a bug report is to enable us to fix the bug if 5234it is new to us. Therefore, always write your bug reports on the assumption 5235that the bug has not been reported previously. 5236 5237Sometimes people give a few sketchy facts and ask, ``Does this ring a 5238bell?'' Those bug reports are useless, and we urge everyone to 5239@emph{refuse to respond to them} except to chide the sender to report 5240bugs properly. 5241 5242To enable us to fix the bug, you should include all these things: 5243 5244@itemize @bullet 5245@item 5246The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start 5247it with the @samp{--version} argument. 5248 5249Without this, we will not know whether there is any point in looking for 5250the bug in the current version of @code{@value{AS}}. 5251 5252@item 5253Any patches you may have applied to the @code{@value{AS}} source. 5254 5255@item 5256The type of machine you are using, and the operating system name and 5257version number. 5258 5259@item 5260What compiler (and its version) was used to compile @code{@value{AS}}---e.g. 5261``@code{gcc-2.7}''. 5262 5263@item 5264The command arguments you gave the assembler to assemble your example and 5265observe the bug. To guarantee you will not omit something important, list them 5266all. A copy of the Makefile (or the output from make) is sufficient. 5267 5268If we were to try to guess the arguments, we would probably guess wrong 5269and then we might not encounter the bug. 5270 5271@item 5272A complete input file that will reproduce the bug. If the bug is observed when 5273the assembler is invoked via a compiler, send the assembler source, not the 5274high level language source. Most compilers will produce the assembler source 5275when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use 5276the options @samp{-v --save-temps}; this will save the assembler source in a 5277file with an extension of @file{.s}, and also show you exactly how 5278@code{@value{AS}} is being run. 5279 5280@item 5281A description of what behavior you observe that you believe is 5282incorrect. For example, ``It gets a fatal signal.'' 5283 5284Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we 5285will certainly notice it. But if the bug is incorrect output, we might not 5286notice unless it is glaringly wrong. You might as well not give us a chance to 5287make a mistake. 5288 5289Even if the problem you experience is a fatal signal, you should still say so 5290explicitly. Suppose something strange is going on, such as, your copy of 5291@code{@value{AS}} is out of synch, or you have encountered a bug in the C 5292library on your system. (This has happened!) Your copy might crash and ours 5293would not. If you told us to expect a crash, then when ours fails to crash, we 5294would know that the bug was not happening for us. If you had not told us to 5295expect a crash, then we would not be able to draw any conclusion from our 5296observations. 5297 5298@item 5299If you wish to suggest changes to the @code{@value{AS}} source, send us context 5300diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} 5301option. Always send diffs from the old file to the new file. If you even 5302discuss something in the @code{@value{AS}} source, refer to it by context, not 5303by line number. 5304 5305The line numbers in our development sources will not match those in your 5306sources. Your line numbers would convey no useful information to us. 5307@end itemize 5308 5309Here are some things that are not necessary: 5310 5311@itemize @bullet 5312@item 5313A description of the envelope of the bug. 5314 5315Often people who encounter a bug spend a lot of time investigating 5316which changes to the input file will make the bug go away and which 5317changes will not affect it. 5318 5319This is often time consuming and not very useful, because the way we 5320will find the bug is by running a single example under the debugger 5321with breakpoints, not by pure deduction from a series of examples. 5322We recommend that you save your time for something else. 5323 5324Of course, if you can find a simpler example to report @emph{instead} 5325of the original one, that is a convenience for us. Errors in the 5326output will be easier to spot, running under the debugger will take 5327less time, and so on. 5328 5329However, simplification is not vital; if you do not want to do this, 5330report the bug anyway and send us the entire test case you used. 5331 5332@item 5333A patch for the bug. 5334 5335A patch for the bug does help us if it is a good one. But do not omit 5336the necessary information, such as the test case, on the assumption that 5337a patch is all we need. We might see problems with your patch and decide 5338to fix the problem another way, or we might not understand it at all. 5339 5340Sometimes with a program as complicated as @code{@value{AS}} it is very hard to 5341construct an example that will make the program follow a certain path through 5342the code. If you do not send us the example, we will not be able to construct 5343one, so we will not be able to verify that the bug is fixed. 5344 5345And if we cannot understand what bug you are trying to fix, or why your 5346patch should be an improvement, we will not install it. A test case will 5347help us to understand. 5348 5349@item 5350A guess about what the bug is or what it depends on. 5351 5352Such guesses are usually wrong. Even we cannot guess right about such 5353things without first using the debugger to find the facts. 5354@end itemize 5355 5356@node Acknowledgements 5357@chapter Acknowledgements 5358 5359If you have contributed to @code{@value{AS}} and your name isn't listed here, 5360it is not meant as a slight. We just don't know about it. Send mail to the 5361maintainer, and we'll correct the situation. Currently 5362@c (January 1994), 5363the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). 5364 5365Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any 5366more details?} 5367 5368Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug 5369information and the 68k series machines, most of the preprocessing pass, and 5370extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. 5371 5372K. Richard Pixley maintained GAS for a while, adding various enhancements and 5373many bug fixes, including merging support for several processors, breaking GAS 5374up to handle multiple object file format back ends (including heavy rewrite, 5375testing, an integration of the coff and b.out back ends), adding configuration 5376including heavy testing and verification of cross assemblers and file splits 5377and renaming, converted GAS to strictly ANSI C including full prototypes, added 5378support for m680[34]0 and cpu32, did considerable work on i960 including a COFF 5379port (including considerable amounts of reverse engineering), a SPARC opcode 5380file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' 5381assertions and made them work, much other reorganization, cleanup, and lint. 5382 5383Ken Raeburn wrote the high-level BFD interface code to replace most of the code 5384in format-specific I/O modules. 5385 5386The original VMS support was contributed by David L. Kashtan. Eric Youngdale 5387has done much work with it since. 5388 5389The Intel 80386 machine description was written by Eliot Dresselhaus. 5390 5391Minh Tran-Le at IntelliCorp contributed some AIX 386 support. 5392 5393The Motorola 88k machine description was contributed by Devon Bowen of Buffalo 5394University and Torbjorn Granlund of the Swedish Institute of Computer Science. 5395 5396Keith Knowles at the Open Software Foundation wrote the original MIPS back end 5397(@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support 5398(which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to 5399support a.out format. 5400 5401Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k, 5402tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by 5403Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to 5404use BFD for some low-level operations, for use with the H8/300 and AMD 29k 5405targets. 5406 5407John Gilmore built the AMD 29000 support, added @code{.include} support, and 5408simplified the configuration of which versions accept which directives. He 5409updated the 68k machine description so that Motorola's opcodes always produced 5410fixed-size instructions (e.g. @code{jsr}), while synthetic instructions 5411remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested 5412cross-compilation support, and one bug in relaxation that took a week and 5413required the proverbial one-bit fix. 5414 5415Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the 541668k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), 5417added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and 5418PowerPC assembler, and made a few other minor patches. 5419 5420Steve Chamberlain made @code{@value{AS}} able to generate listings. 5421 5422Hewlett-Packard contributed support for the HP9000/300. 5423 5424Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) 5425along with a fairly extensive HPPA testsuite (for both SOM and ELF object 5426formats). This work was supported by both the Center for Software Science at 5427the University of Utah and Cygnus Support. 5428 5429Support for ELF format files has been worked on by Mark Eichin of Cygnus 5430Support (original, incomplete implementation for SPARC), Pete Hoogenboom and 5431Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open 5432Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, 5433and some initial 64-bit support). 5434 5435Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture. 5436 5437Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD 5438support for openVMS/Alpha. 5439 5440Several engineers at Cygnus Support have also provided many small bug fixes and 5441configuration enhancements. 5442 5443Many others have contributed large or small bugfixes and enhancements. If 5444you have contributed significant work and are not mentioned on this list, and 5445want to be, let us know. Some of the history has been lost; we are not 5446intentionally leaving anyone out. 5447 5448@node Index 5449@unnumbered Index 5450 5451@printindex cp 5452 5453@contents 5454@bye 5455@c Local Variables: 5456@c fill-column: 79 5457@c End: 5458