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66b818fb | 1 | \input texinfo @c -*-Texinfo-*- |
ef582182 NC |
2 | @c Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 1998 |
3 | @c Free Software Foundation, Inc. | |
e680d737 RP |
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 | |
f009d0ab RP |
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 --- | |
4b9f4409 | 18 | @include asconfig.texi |
1ca26844 | 19 | @include gasver.texi |
f009d0ab RP |
20 | @c --- |
21 | @c common OR combinations of conditions | |
22 | @ifset AOUT | |
23 | @set aout-bout | |
24 | @end ifset | |
3ffb03b1 DE |
25 | @ifset ARM/Thumb |
26 | @set ARM | |
27 | @end ifset | |
f009d0ab RP |
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 | |
f009d0ab RP |
37 | @ifset SH |
38 | @set H8 | |
39 | @end ifset | |
9dcf8057 JL |
40 | @ifset HPPA |
41 | @set abnormal-separator | |
42 | @end ifset | |
f009d0ab RP |
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 | |
66b818fb | 50 | @setchapternewpage odd |
66b818fb RP |
51 | @c %**end of header |
52 | ||
fb5bec49 RP |
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 | ||
80381063 RP |
76 | @ifinfo |
77 | @format | |
dd565f85 RP |
78 | START-INFO-DIR-ENTRY |
79 | * As: (as). The GNU assembler. | |
80 | END-INFO-DIR-ENTRY | |
80381063 RP |
81 | @end format |
82 | @end ifinfo | |
83 | ||
66b818fb RP |
84 | @finalout |
85 | @syncodeindex ky cp | |
86 | ||
47342e8f | 87 | @ifinfo |
f009d0ab | 88 | This file documents the GNU Assembler "@value{AS}". |
47342e8f | 89 | |
ef582182 | 90 | Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc. |
47342e8f RP |
91 | |
92 | Permission is granted to make and distribute verbatim copies of | |
93 | this manual provided the copyright notice and this permission notice | |
94 | are preserved on all copies. | |
95 | ||
96 | @ignore | |
97 | Permission is granted to process this file through Tex and print the | |
98 | results, provided the printed document carries copying permission | |
99 | notice 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 | |
81fcb3ff RP |
103 | Permission is granted to copy and distribute modified versions of this manual |
104 | under the conditions for verbatim copying, provided that the entire resulting | |
105 | derived work is distributed under the terms of a permission notice identical to | |
106 | this one. | |
47342e8f RP |
107 | |
108 | Permission is granted to copy and distribute translations of this manual | |
81fcb3ff | 109 | into another language, under the above conditions for modified versions. |
47342e8f | 110 | @end ifinfo |
66b818fb | 111 | |
93b45514 | 112 | @titlepage |
f009d0ab | 113 | @title Using @value{AS} |
71dd3c40 | 114 | @subtitle The @sc{gnu} Assembler |
f009d0ab RP |
115 | @ifclear GENERIC |
116 | @subtitle for the @value{TARGET} family | |
117 | @end ifclear | |
93b45514 | 118 | @sp 1 |
1ca26844 | 119 | @subtitle Version @value{VERSION} |
0b5b143a | 120 | @sp 1 |
93b45514 RP |
121 | @sp 13 |
122 | The Free Software Foundation Inc. thanks The Nice Computer | |
123 | Company of Australia for loaning Dean Elsner to write the | |
71dd3c40 | 124 | first (Vax) version of @code{as} for Project @sc{gnu}. |
93b45514 RP |
125 | The proprietors, management and staff of TNCCA thank FSF for |
126 | distracting the boss while they got some work | |
127 | done. | |
128 | @sp 3 | |
7d7ecbdd | 129 | @author Dean Elsner, Jay Fenlason & friends |
47342e8f RP |
130 | @page |
131 | @tex | |
47342e8f | 132 | {\parskip=0pt |
f009d0ab | 133 | \hfill {\it Using {\tt @value{AS}}}\par |
71dd3c40 | 134 | \hfill Edited by Cygnus Support\par |
47342e8f | 135 | } |
b50e59fe RP |
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 | |
47342e8f | 142 | @end tex |
93b45514 | 143 | |
47342e8f | 144 | @vskip 0pt plus 1filll |
ef582182 | 145 | Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc. |
93b45514 RP |
146 | |
147 | Permission is granted to make and distribute verbatim copies of | |
148 | this manual provided the copyright notice and this permission notice | |
149 | are preserved on all copies. | |
150 | ||
81fcb3ff RP |
151 | Permission is granted to copy and distribute modified versions of this manual |
152 | under the conditions for verbatim copying, provided that the entire resulting | |
153 | derived work is distributed under the terms of a permission notice identical to | |
154 | this one. | |
93b45514 RP |
155 | |
156 | Permission is granted to copy and distribute translations of this manual | |
81fcb3ff | 157 | into another language, under the above conditions for modified versions. |
93b45514 | 158 | @end titlepage |
f009d0ab | 159 | |
d0281557 | 160 | @ifinfo |
242d9c06 | 161 | @node Top |
f009d0ab | 162 | @top Using @value{AS} |
242d9c06 | 163 | |
1ca26844 ILT |
164 | This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version |
165 | @value{VERSION}. | |
f009d0ab RP |
166 | @ifclear GENERIC |
167 | This version of the file describes @code{@value{AS}} configured to generate | |
168 | code for @value{TARGET} architectures. | |
169 | @end ifclear | |
7a4c8e5c | 170 | @menu |
ba487f3a RP |
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 | |
f009d0ab | 178 | * Machine Dependencies:: Machine Dependent Features |
9a5acea8 | 179 | * Reporting Bugs:: Reporting Bugs |
9dcf8057 | 180 | * Acknowledgements:: Who Did What |
66b818fb | 181 | * Index:: Index |
7a4c8e5c | 182 | @end menu |
242d9c06 | 183 | @end ifinfo |
7a4c8e5c | 184 | |
242d9c06 | 185 | @node Overview |
b50e59fe | 186 | @chapter Overview |
d0281557 | 187 | @iftex |
8babef85 | 188 | This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}. |
f009d0ab RP |
189 | @ifclear GENERIC |
190 | This version of the manual describes @code{@value{AS}} configured to generate | |
191 | code for @value{TARGET} architectures. | |
192 | @end ifclear | |
d0281557 | 193 | @end iftex |
b50e59fe | 194 | |
66b818fb RP |
195 | @cindex invocation summary |
196 | @cindex option summary | |
197 | @cindex summary of options | |
f009d0ab | 198 | Here is a brief summary of how to invoke @code{@value{AS}}. For details, |
7a4c8e5c | 199 | @pxref{Invoking,,Comand-Line Options}. |
b50e59fe | 200 | |
7d7ecbdd | 201 | @c We don't use deffn and friends for the following because they seem |
b50e59fe | 202 | @c to be limited to one line for the header. |
d0281557 | 203 | @smallexample |
35cfacf0 | 204 | @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ] |
cd924033 | 205 | [ -f ] [ --gstabs ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ] |
c3b27a64 RH |
206 | [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ] |
207 | [ -version ] [ --version ] [ -W ] [ -w ] [ -x ] [ -Z ] | |
f009d0ab | 208 | @ifset A29K |
2d8e0f62 | 209 | @c am29k has no machine-dependent assembler options |
f009d0ab | 210 | @end ifset |
99c4053d KR |
211 | @ifset ARC |
212 | [ -mbig-endian | -mlittle-endian ] | |
213 | @end ifset | |
3ffb03b1 DE |
214 | @ifset ARM |
215 | [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]7[t][[d]m[i]] ] | |
216 | [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t ] | |
217 | [ -mthumb | -mall ] | |
218 | [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ] | |
219 | [ -EB | -EL ] | |
220 | [ -mapcs-32 | -mapcs-26 ] | |
221 | @end ifset | |
9a5acea8 ILT |
222 | @ifset D10V |
223 | [ -O ] | |
224 | @end ifset | |
c3b27a64 RH |
225 | @ifset D30V |
226 | [ -O | -n | -N ] | |
227 | @end ifset | |
f009d0ab RP |
228 | @ifset H8 |
229 | @c Hitachi family chips have no machine-dependent assembler options | |
230 | @end ifset | |
9dcf8057 JL |
231 | @ifset HPPA |
232 | @c HPPA has no machine-dependent assembler options (yet). | |
233 | @end ifset | |
f009d0ab | 234 | @ifset SPARC |
71dd3c40 | 235 | @c The order here is important. See c-sparc.texi. |
945229ab DE |
236 | [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
237 | -Av8plus | -Av8plusa | -Av9 | -Av9a ] | |
ee73be40 | 238 | [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ] |
f009d0ab RP |
239 | @end ifset |
240 | @ifset Z8000 | |
2d8e0f62 | 241 | @c Z8000 has no machine-dependent assembler options |
f009d0ab RP |
242 | @end ifset |
243 | @ifset I960 | |
9ebc250f | 244 | @c see md_parse_option in tc-i960.c |
81fcb3ff | 245 | [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ] |
b3b2623c | 246 | [ -b ] [ -no-relax ] |
f009d0ab | 247 | @end ifset |
d745e6d9 | 248 | @c start-sanitize-m32rx |
ee73be40 | 249 | @ifset M32R |
71c2d792 | 250 | [ --m32rx | --[no-]warn-explicit-parallel-conflicts | --W[n]p ] |
ee73be40 | 251 | @end ifset |
c3b27a64 | 252 | @c end-sanitize-m32rx |
f009d0ab | 253 | @ifset M680X0 |
81fcb3ff | 254 | [ -l ] [ -m68000 | -m68010 | -m68020 | ... ] |
34214344 KR |
255 | @end ifset |
256 | @ifset MIPS | |
b3b2623c KR |
257 | [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ] |
258 | [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -m4650 ] [ -no-m4650 ] | |
dd565f85 | 259 | [ --trap ] [ --break ] |
ba5ceb30 | 260 | [ --emulation=@var{name} ] |
f009d0ab | 261 | @end ifset |
81fcb3ff | 262 | [ -- | @var{files} @dots{} ] |
d0281557 | 263 | @end smallexample |
47342e8f RP |
264 | |
265 | @table @code | |
68eaa141 | 266 | @item -a[cdhlmns] |
05a0e43b RP |
267 | Turn on listings, in any of a variety of ways: |
268 | ||
269 | @table @code | |
68eaa141 NC |
270 | @item -ac |
271 | omit false conditionals | |
272 | ||
05a0e43b | 273 | @item -ad |
b3b2623c | 274 | omit debugging directives |
05a0e43b RP |
275 | |
276 | @item -ah | |
277 | include high-level source | |
278 | ||
279 | @item -al | |
b3b2623c | 280 | include assembly |
05a0e43b | 281 | |
68eaa141 NC |
282 | @item -am |
283 | include macro expansions | |
284 | ||
05a0e43b | 285 | @item -an |
b3b2623c | 286 | omit forms processing |
05a0e43b RP |
287 | |
288 | @item -as | |
b3b2623c | 289 | include symbols |
85a961c6 ILT |
290 | |
291 | @item =file | |
292 | set the name of the listing file | |
05a0e43b RP |
293 | @end table |
294 | ||
295 | You may combine these options; for example, use @samp{-aln} for assembly | |
85a961c6 | 296 | listing without forms processing. The @samp{=file} option, if used, must be |
68eaa141 | 297 | the last one. By itself, @samp{-a} defaults to @samp{-ahls}. |
b50e59fe RP |
298 | |
299 | @item -D | |
b3b2623c KR |
300 | Ignored. This option is accepted for script compatibility with calls to |
301 | other assemblers. | |
b50e59fe | 302 | |
71dd3c40 ILT |
303 | @item --defsym @var{sym}=@var{value} |
304 | Define the symbol @var{sym} to be @var{value} before assembling the input file. | |
305 | @var{value} must be an integer constant. As in C, a leading @samp{0x} | |
306 | indicates a hexadecimal value, and a leading @samp{0} indicates an octal value. | |
307 | ||
47342e8f | 308 | @item -f |
9dcf8057 | 309 | ``fast''---skip whitespace and comment preprocessing (assume source is |
b3b2623c | 310 | compiler output). |
47342e8f | 311 | |
cd924033 ILT |
312 | @item --gstabs |
313 | Generate stabs debugging information for each assembler line. This | |
314 | may help debugging assembler code, if the debugger can handle it. | |
315 | ||
b3b2623c KR |
316 | @item --help |
317 | Print a summary of the command line options and exit. | |
318 | ||
319 | @item -I @var{dir} | |
320 | Add directory @var{dir} to the search list for @code{.include} directives. | |
321 | ||
322 | @item -J | |
323 | Don't warn about signed overflow. | |
b50e59fe | 324 | |
80381063 | 325 | @item -K |
f009d0ab RP |
326 | @ifclear DIFF-TBL-KLUGE |
327 | This option is accepted but has no effect on the @value{TARGET} family. | |
328 | @end ifclear | |
329 | @ifset DIFF-TBL-KLUGE | |
0b5b143a | 330 | Issue warnings when difference tables altered for long displacements. |
f009d0ab | 331 | @end ifset |
47342e8f RP |
332 | |
333 | @item -L | |
c3b27a64 RH |
334 | @itemx --keep-locals |
335 | Keep (in the symbol table) local symbols. On traditional a.out systems | |
336 | these start with @samp{L}, but different systems have different local | |
337 | label prefixes. | |
47342e8f RP |
338 | |
339 | @item -o @var{objfile} | |
b3b2623c | 340 | Name the object-file output from @code{@value{AS}} @var{objfile}. |
47342e8f RP |
341 | |
342 | @item -R | |
b3b2623c | 343 | Fold the data section into the text section. |
47342e8f | 344 | |
62e59d28 | 345 | @item --statistics |
b3b2623c | 346 | Print the maximum space (in bytes) and total time (in seconds) used by |
62e59d28 RP |
347 | assembly. |
348 | ||
c3b27a64 RH |
349 | @item --strip-local-absolute |
350 | Remove local absolute symbols from the outgoing symbol table. | |
351 | ||
7d7ecbdd | 352 | @item -v |
b3b2623c KR |
353 | @itemx -version |
354 | Print the @code{as} version. | |
355 | ||
356 | @item --version | |
357 | Print the @code{as} version and exit. | |
7d7ecbdd | 358 | |
47342e8f | 359 | @item -W |
b3b2623c KR |
360 | Suppress warning messages. |
361 | ||
362 | @item -w | |
363 | Ignored. | |
364 | ||
365 | @item -x | |
366 | Ignored. | |
47342e8f | 367 | |
62e59d28 | 368 | @item -Z |
b3b2623c | 369 | Generate an object file even after errors. |
62e59d28 | 370 | |
9ebc250f KR |
371 | @item -- | @var{files} @dots{} |
372 | Standard input, or source files to assemble. | |
9ebc250f KR |
373 | |
374 | @end table | |
375 | ||
99c4053d KR |
376 | @ifset ARC |
377 | The following options are available when @value{AS} is configured for | |
378 | an ARC processor. | |
379 | ||
380 | @table @code | |
381 | ||
382 | @cindex ARC endianness | |
383 | @cindex endianness, ARC | |
384 | @cindex big endian output, ARC | |
385 | @item -mbig-endian | |
386 | Generate ``big endian'' format output. | |
387 | ||
388 | @cindex little endian output, ARC | |
389 | @item -mlittle-endian | |
390 | Generate ``little endian'' format output. | |
391 | ||
392 | @end table | |
393 | @end ifset | |
394 | ||
3ffb03b1 DE |
395 | @ifset ARM |
396 | The following options are available when @value{AS} is configured for the ARM | |
397 | processor family. | |
398 | ||
399 | @table @code | |
400 | @item -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]7[t][[d]m] | -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t | |
401 | Specify which variant of the ARM architecture is the target. | |
402 | @item -mthumb | -mall | |
403 | Enable or disable Thumb only instruction decoding. | |
404 | @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu | |
405 | Select which Floating Point architcture is the target. | |
406 | @item -mapcs-32 | -mapcs-26 | |
407 | Select which procedure calling convention is in use. | |
408 | @item -EB | -EL | |
409 | Select either big-endian (-EB) or little-endian (-EL) output. | |
410 | @end table | |
411 | @end ifset | |
412 | ||
9a5acea8 ILT |
413 | @ifset D10V |
414 | The following options are available when @value{AS} is configured for | |
415 | a D10V processor. | |
416 | @table @code | |
417 | @cindex D10V optimization | |
418 | @cindex optimization, D10V | |
419 | @item -O | |
420 | Optimize output by parallelizing instructions. | |
421 | @end table | |
422 | @end ifset | |
9a5acea8 | 423 | |
c3b27a64 RH |
424 | @ifset D30V |
425 | The following options are available when @value{AS} is configured for a D30V | |
426 | processor. | |
427 | @table @code | |
428 | @cindex D30V optimization | |
429 | @cindex optimization, D30V | |
430 | @item -O | |
431 | Optimize output by parallelizing instructions. | |
432 | ||
433 | @cindex D30V nops | |
434 | @item -n | |
435 | Warn when nops are generated. | |
436 | ||
437 | @cindex D30V nops after 32-bit multiply | |
438 | @item -N | |
439 | Warn when a nop after a 32-bit multiply instruction is generated. | |
440 | @end table | |
441 | @end ifset | |
c3b27a64 | 442 | |
f009d0ab RP |
443 | @ifset I960 |
444 | The following options are available when @value{AS} is configured for the | |
9ebc250f KR |
445 | Intel 80960 processor. |
446 | ||
447 | @table @code | |
d0281557 RP |
448 | @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC |
449 | Specify which variant of the 960 architecture is the target. | |
450 | ||
451 | @item -b | |
452 | Add code to collect statistics about branches taken. | |
453 | ||
b3b2623c | 454 | @item -no-relax |
66b818fb | 455 | Do not alter compare-and-branch instructions for long displacements; |
d0281557 | 456 | error if necessary. |
9ebc250f KR |
457 | |
458 | @end table | |
f009d0ab | 459 | @end ifset |
d0281557 | 460 | |
d745e6d9 | 461 | @c start-sanitize-m32rx |
ee73be40 NC |
462 | @ifset M32R |
463 | The following options are available when @value{AS} is configured for the | |
464 | Mitsubishi M32R series. | |
465 | ||
466 | @table @code | |
467 | ||
468 | @item --m32rx | |
469 | Specify which processor in the M32R family is the target. The default | |
470 | is normally the M32R, but this option changes it to the M32RX. | |
471 | ||
71c2d792 | 472 | @item --warn-explicit-parallel-conflicts or --Wp |
ef582182 NC |
473 | Produce warning messages when questionable parallel constructs are |
474 | encountered. | |
475 | ||
71c2d792 | 476 | @item --no-warn-explicit-parallel-conflicts or --Wnp |
ef582182 NC |
477 | Do not produce warning messages when questionable parallel constructs are |
478 | encountered. | |
479 | ||
ee73be40 NC |
480 | @end table |
481 | @end ifset | |
d745e6d9 | 482 | @c end-sanitize-m32rx |
ee73be40 | 483 | |
f009d0ab RP |
484 | @ifset M680X0 |
485 | The following options are available when @value{AS} is configured for the | |
9ebc250f KR |
486 | Motorola 68000 series. |
487 | ||
488 | @table @code | |
489 | ||
09352a5d | 490 | @item -l |
9ebc250f | 491 | Shorten references to undefined symbols, to one word instead of two. |
09352a5d | 492 | |
910d7df2 C |
493 | @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060 |
494 | @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200 | |
9ebc250f KR |
495 | Specify what processor in the 68000 family is the target. The default |
496 | is normally the 68020, but this can be changed at configuration time. | |
497 | ||
498 | @item -m68881 | -m68882 | -mno-68881 | -mno-68882 | |
499 | The target machine does (or does not) have a floating-point coprocessor. | |
500 | The default is to assume a coprocessor for 68020, 68030, and cpu32. Although | |
501 | the basic 68000 is not compatible with the 68881, a combination of the | |
502 | two can be specified, since it's possible to do emulation of the | |
503 | coprocessor instructions with the main processor. | |
504 | ||
505 | @item -m68851 | -mno-68851 | |
506 | The target machine does (or does not) have a memory-management | |
507 | unit coprocessor. The default is to assume an MMU for 68020 and up. | |
47342e8f | 508 | |
47342e8f | 509 | @end table |
f009d0ab RP |
510 | @end ifset |
511 | ||
512 | @ifset SPARC | |
513 | The following options are available when @code{@value{AS}} is configured | |
514 | for the SPARC architecture: | |
515 | ||
516 | @table @code | |
945229ab DE |
517 | @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
518 | @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a | |
f009d0ab RP |
519 | Explicitly select a variant of the SPARC architecture. |
520 | ||
945229ab DE |
521 | @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. |
522 | @samp{-Av9} and @samp{-Av9a} select a 64 bit environment. | |
523 | ||
524 | @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with | |
525 | UltraSPARC extensions. | |
526 | ||
71dd3c40 ILT |
527 | @item -xarch=v8plus | -xarch=v8plusa |
528 | For compatibility with the Solaris v9 assembler. These options are | |
945229ab | 529 | equivalent to -Av8plus and -Av8plusa, respectively. |
71dd3c40 | 530 | |
f009d0ab RP |
531 | @item -bump |
532 | Warn when the assembler switches to another architecture. | |
533 | @end table | |
534 | @end ifset | |
47342e8f | 535 | |
34214344 KR |
536 | @ifset MIPS |
537 | The following options are available when @value{AS} is configured for | |
dd565f85 | 538 | a MIPS processor. |
34214344 KR |
539 | |
540 | @table @code | |
34214344 | 541 | @item -G @var{num} |
05a0e43b | 542 | This option sets the largest size of an object that can be referenced |
dd565f85 RP |
543 | implicitly with the @code{gp} register. It is only accepted for targets that |
544 | use ECOFF format, such as a DECstation running Ultrix. The default value is 8. | |
34214344 | 545 | |
05a0e43b RP |
546 | @cindex MIPS endianness |
547 | @cindex endianness, MIPS | |
05a0e43b | 548 | @cindex big endian output, MIPS |
dd565f85 | 549 | @item -EB |
05a0e43b RP |
550 | Generate ``big endian'' format output. |
551 | ||
05a0e43b | 552 | @cindex little endian output, MIPS |
dd565f85 | 553 | @item -EL |
05a0e43b | 554 | Generate ``little endian'' format output. |
34214344 | 555 | |
1051c97f ILT |
556 | @cindex MIPS ISA |
557 | @item -mips1 | |
dd565f85 RP |
558 | @itemx -mips2 |
559 | @itemx -mips3 | |
560 | Generate code for a particular MIPS Instruction Set Architecture level. | |
561 | @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors, | |
562 | @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000} | |
563 | processor. | |
1051c97f | 564 | |
b3b2623c | 565 | @item -m4650 |
71c2d792 | 566 | @itemx -no-m4650 |
b3b2623c KR |
567 | Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept |
568 | the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop} | |
569 | instructions around accesses to the @samp{HI} and @samp{LO} registers. | |
570 | @samp{-no-m4650} turns off this option. | |
571 | ||
572 | @item -mcpu=@var{CPU} | |
573 | Generate code for a particular MIPS cpu. This has little effect on the | |
574 | assembler, but it is passed by @code{@value{GCC}}. | |
575 | ||
ba5ceb30 KR |
576 | @cindex emulation |
577 | @item --emulation=@var{name} | |
3ffb03b1 | 578 | This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured |
ba5ceb30 KR |
579 | for some other target, in all respects, including output format (choosing |
580 | between ELF and ECOFF only), handling of pseudo-opcodes which may generate | |
581 | debugging information or store symbol table information, and default | |
582 | endianness. The available configuration names are: @samp{mipsecoff}, | |
583 | @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf}, | |
584 | @samp{mipsbelf}. The first two do not alter the default endianness from that | |
585 | of the primary target for which the assembler was configured; the others change | |
586 | the default to little- or big-endian as indicated by the @samp{b} or @samp{l} | |
587 | in the name. Using @samp{-EB} or @samp{-EL} will override the endianness | |
588 | selection in any case. | |
589 | ||
590 | This option is currently supported only when the primary target | |
591 | @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target. | |
592 | Furthermore, the primary target or others specified with | |
593 | @samp{--enable-targets=@dots{}} at configuration time must include support for | |
594 | the other format, if both are to be available. For example, the Irix 5 | |
595 | configuration includes support for both. | |
596 | ||
597 | Eventually, this option will support more configurations, with more | |
598 | fine-grained control over the assembler's behavior, and will be supported for | |
599 | more processors. | |
600 | ||
05a0e43b | 601 | @item -nocpp |
dd565f85 RP |
602 | @code{@value{AS}} ignores this option. It is accepted for compatibility with |
603 | the native tools. | |
604 | ||
71dd3c40 | 605 | @need 900 |
dd565f85 RP |
606 | @item --trap |
607 | @itemx --no-trap | |
608 | @itemx --break | |
609 | @itemx --no-break | |
610 | Control how to deal with multiplication overflow and division by zero. | |
611 | @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception | |
612 | (and only work for Instruction Set Architecture level 2 and higher); | |
613 | @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a | |
614 | break exception. | |
34214344 KR |
615 | @end table |
616 | @end ifset | |
617 | ||
7a4c8e5c | 618 | @menu |
ba487f3a | 619 | * Manual:: Structure of this Manual |
3ffb03b1 | 620 | * GNU Assembler:: The GNU Assembler |
ba487f3a RP |
621 | * Object Formats:: Object File Formats |
622 | * Command Line:: Command Line | |
623 | * Input Files:: Input Files | |
624 | * Object:: Output (Object) File | |
625 | * Errors:: Error and Warning Messages | |
7a4c8e5c RP |
626 | @end menu |
627 | ||
242d9c06 | 628 | @node Manual |
d0281557 | 629 | @section Structure of this Manual |
66b818fb RP |
630 | |
631 | @cindex manual, structure and purpose | |
632 | This manual is intended to describe what you need to know to use | |
f009d0ab | 633 | @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including |
47342e8f | 634 | notation for symbols, constants, and expressions; the directives that |
f009d0ab | 635 | @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}. |
47342e8f | 636 | |
f009d0ab RP |
637 | @ifclear GENERIC |
638 | We also cover special features in the @value{TARGET} | |
639 | configuration of @code{@value{AS}}, including assembler directives. | |
640 | @end ifclear | |
641 | @ifset GENERIC | |
66b818fb | 642 | This manual also describes some of the machine-dependent features of |
09352a5d | 643 | various flavors of the assembler. |
f009d0ab | 644 | @end ifset |
93b45514 | 645 | |
66b818fb | 646 | @cindex machine instructions (not covered) |
47342e8f | 647 | On the other hand, this manual is @emph{not} intended as an introduction |
b50e59fe RP |
648 | to programming in assembly language---let alone programming in general! |
649 | In a similar vein, we make no attempt to introduce the machine | |
47342e8f RP |
650 | architecture; we do @emph{not} describe the instruction set, standard |
651 | mnemonics, registers or addressing modes that are standard to a | |
f009d0ab RP |
652 | particular architecture. |
653 | @ifset GENERIC | |
66b818fb | 654 | You may want to consult the manufacturer's |
b50e59fe | 655 | machine architecture manual for this information. |
f009d0ab RP |
656 | @end ifset |
657 | @ifclear GENERIC | |
658 | @ifset H8/300 | |
66b818fb | 659 | For information on the H8/300 machine instruction set, see @cite{H8/300 |
8d8ddccb RP |
660 | Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H, |
661 | see @cite{H8/300H Series Programming Manual} (Hitachi). | |
f009d0ab RP |
662 | @end ifset |
663 | @ifset H8/500 | |
664 | For information on the H8/500 machine instruction set, see @cite{H8/500 | |
665 | Series Programming Manual} (Hitachi M21T001). | |
666 | @end ifset | |
f009d0ab RP |
667 | @ifset SH |
668 | For information on the Hitachi SH machine instruction set, see | |
669 | @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.). | |
670 | @end ifset | |
f009d0ab | 671 | @ifset Z8000 |
2d8e0f62 | 672 | For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} |
f009d0ab RP |
673 | @end ifset |
674 | @end ifclear | |
93b45514 | 675 | |
71dd3c40 | 676 | @c I think this is premature---doc@cygnus.com, 17jan1991 |
47342e8f | 677 | @ignore |
66b818fb | 678 | Throughout this manual, we assume that you are running @dfn{GNU}, |
93b45514 RP |
679 | the portable operating system from the @dfn{Free Software |
680 | Foundation, Inc.}. This restricts our attention to certain kinds of | |
8babef85 | 681 | computer (in particular, the kinds of computers that @sc{gnu} can run on); |
93b45514 RP |
682 | once this assumption is granted examples and definitions need less |
683 | qualification. | |
684 | ||
f009d0ab | 685 | @code{@value{AS}} is part of a team of programs that turn a high-level |
93b45514 RP |
686 | human-readable series of instructions into a low-level |
687 | computer-readable series of instructions. Different versions of | |
f009d0ab | 688 | @code{@value{AS}} are used for different kinds of computer. |
47342e8f | 689 | @end ignore |
93b45514 | 690 | |
b50e59fe RP |
691 | @c There used to be a section "Terminology" here, which defined |
692 | @c "contents", "byte", "word", and "long". Defining "word" to any | |
693 | @c particular size is confusing when the .word directive may generate 16 | |
694 | @c bits on one machine and 32 bits on another; in general, for the user | |
695 | @c version of this manual, none of these terms seem essential to define. | |
696 | @c They were used very little even in the former draft of the manual; | |
697 | @c this draft makes an effort to avoid them (except in names of | |
d0281557 RP |
698 | @c directives). |
699 | ||
242d9c06 | 700 | @node GNU Assembler |
3ffb03b1 | 701 | @section The GNU Assembler |
66b818fb | 702 | |
8babef85 | 703 | @sc{gnu} @code{as} is really a family of assemblers. |
f009d0ab RP |
704 | @ifclear GENERIC |
705 | This manual describes @code{@value{AS}}, a member of that family which is | |
706 | configured for the @value{TARGET} architectures. | |
707 | @end ifclear | |
8babef85 | 708 | If you use (or have used) the @sc{gnu} assembler on one architecture, you |
7a4c8e5c RP |
709 | should find a fairly similar environment when you use it on another |
710 | architecture. Each version has much in common with the others, | |
711 | including object file formats, most assembler directives (often called | |
9ebc250f | 712 | @dfn{pseudo-ops}) and assembler syntax.@refill |
d0281557 | 713 | |
3ffb03b1 | 714 | @cindex purpose of @sc{gnu} assembler |
f009d0ab | 715 | @code{@value{AS}} is primarily intended to assemble the output of the |
8babef85 | 716 | @sc{gnu} C compiler @code{@value{GCC}} for use by the linker |
f009d0ab RP |
717 | @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}} |
718 | assemble correctly everything that other assemblers for the same | |
719 | machine would assemble. | |
720 | @ifset VAX | |
721 | Any exceptions are documented explicitly (@pxref{Machine Dependencies}). | |
722 | @end ifset | |
723 | @ifset M680X0 | |
724 | @c This remark should appear in generic version of manual; assumption | |
725 | @c here is that generic version sets M680x0. | |
726 | This doesn't mean @code{@value{AS}} always uses the same syntax as another | |
b50e59fe RP |
727 | assembler for the same architecture; for example, we know of several |
728 | incompatible versions of 680x0 assembly language syntax. | |
f009d0ab | 729 | @end ifset |
47342e8f | 730 | |
f009d0ab | 731 | Unlike older assemblers, @code{@value{AS}} is designed to assemble a source |
b50e59fe | 732 | program in one pass of the source file. This has a subtle impact on the |
7a4c8e5c | 733 | @kbd{.org} directive (@pxref{Org,,@code{.org}}). |
93b45514 | 734 | |
242d9c06 | 735 | @node Object Formats |
d0281557 | 736 | @section Object File Formats |
66b818fb RP |
737 | |
738 | @cindex object file format | |
8babef85 | 739 | The @sc{gnu} assembler can be configured to produce several alternative |
7d7ecbdd RP |
740 | object file formats. For the most part, this does not affect how you |
741 | write assembly language programs; but directives for debugging symbols | |
742 | are typically different in different file formats. @xref{Symbol | |
743 | Attributes,,Symbol Attributes}. | |
f009d0ab RP |
744 | @ifclear GENERIC |
745 | @ifclear MULTI-OBJ | |
746 | On the @value{TARGET}, @code{@value{AS}} is configured to produce | |
747 | @value{OBJ-NAME} format object files. | |
748 | @end ifclear | |
749 | @c The following should exhaust all configs that set MULTI-OBJ, ideally | |
750 | @ifset A29K | |
751 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
24b1493d | 752 | @code{a.out} or COFF format object files. |
f009d0ab RP |
753 | @end ifset |
754 | @ifset I960 | |
755 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
756 | @code{b.out} or COFF format object files. | |
757 | @end ifset | |
9dcf8057 JL |
758 | @ifset HPPA |
759 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
760 | SOM or ELF format object files. | |
761 | @end ifset | |
f009d0ab | 762 | @end ifclear |
d0281557 | 763 | |
242d9c06 | 764 | @node Command Line |
b50e59fe | 765 | @section Command Line |
93b45514 | 766 | |
66b818fb | 767 | @cindex command line conventions |
f009d0ab | 768 | After the program name @code{@value{AS}}, the command line may contain |
66b818fb | 769 | options and file names. Options may appear in any order, and may be |
93b45514 RP |
770 | before, after, or between file names. The order of file names is |
771 | significant. | |
772 | ||
66b818fb RP |
773 | @cindex standard input, as input file |
774 | @kindex -- | |
47342e8f | 775 | @file{--} (two hyphens) by itself names the standard input file |
f009d0ab | 776 | explicitly, as one of the files for @code{@value{AS}} to assemble. |
47342e8f | 777 | |
66b818fb | 778 | @cindex options, command line |
93b45514 RP |
779 | Except for @samp{--} any command line argument that begins with a |
780 | hyphen (@samp{-}) is an option. Each option changes the behavior of | |
f009d0ab | 781 | @code{@value{AS}}. No option changes the way another option works. An |
47342e8f | 782 | option is a @samp{-} followed by one or more letters; the case of |
b50e59fe | 783 | the letter is important. All options are optional. |
93b45514 RP |
784 | |
785 | Some options expect exactly one file name to follow them. The file | |
786 | name may either immediately follow the option's letter (compatible | |
8babef85 | 787 | with older assemblers) or it may be the next command argument (@sc{gnu} |
93b45514 RP |
788 | standard). These two command lines are equivalent: |
789 | ||
d0281557 | 790 | @smallexample |
f009d0ab RP |
791 | @value{AS} -o my-object-file.o mumble.s |
792 | @value{AS} -omy-object-file.o mumble.s | |
d0281557 | 793 | @end smallexample |
93b45514 | 794 | |
242d9c06 | 795 | @node Input Files |
47342e8f | 796 | @section Input Files |
93b45514 | 797 | |
66b818fb RP |
798 | @cindex input |
799 | @cindex source program | |
800 | @cindex files, input | |
47342e8f | 801 | We use the phrase @dfn{source program}, abbreviated @dfn{source}, to |
f009d0ab | 802 | describe the program input to one run of @code{@value{AS}}. The program may |
93b45514 RP |
803 | be in one or more files; how the source is partitioned into files |
804 | doesn't change the meaning of the source. | |
805 | ||
b50e59fe | 806 | @c I added "con" prefix to "catenation" just to prove I can overcome my |
71dd3c40 | 807 | @c APL training... doc@cygnus.com |
b50e59fe | 808 | The source program is a concatenation of the text in all the files, in the |
47342e8f | 809 | order specified. |
93b45514 | 810 | |
f009d0ab | 811 | Each time you run @code{@value{AS}} it assembles exactly one source |
47342e8f | 812 | program. The source program is made up of one or more files. |
93b45514 RP |
813 | (The standard input is also a file.) |
814 | ||
f009d0ab | 815 | You give @code{@value{AS}} a command line that has zero or more input file |
93b45514 RP |
816 | names. The input files are read (from left file name to right). A |
817 | command line argument (in any position) that has no special meaning | |
d0281557 | 818 | is taken to be an input file name. |
93b45514 | 819 | |
f009d0ab RP |
820 | If you give @code{@value{AS}} no file names it attempts to read one input file |
821 | from the @code{@value{AS}} standard input, which is normally your terminal. You | |
822 | may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program | |
d0281557 | 823 | to assemble. |
93b45514 | 824 | |
47342e8f RP |
825 | Use @samp{--} if you need to explicitly name the standard input file |
826 | in your command line. | |
93b45514 | 827 | |
05a0e43b | 828 | If the source is empty, @code{@value{AS}} produces a small, empty object |
d0281557 | 829 | file. |
b50e59fe | 830 | |
7a4c8e5c | 831 | @subheading Filenames and Line-numbers |
66b818fb RP |
832 | |
833 | @cindex input file linenumbers | |
834 | @cindex line numbers, in input files | |
835 | There are two ways of locating a line in the input file (or files) and | |
836 | either may be used in reporting error messages. One way refers to a line | |
93b45514 | 837 | number in a physical file; the other refers to a line number in a |
66b818fb | 838 | ``logical'' file. @xref{Errors, ,Error and Warning Messages}. |
93b45514 RP |
839 | |
840 | @dfn{Physical files} are those files named in the command line given | |
f009d0ab | 841 | to @code{@value{AS}}. |
93b45514 | 842 | |
47342e8f | 843 | @dfn{Logical files} are simply names declared explicitly by assembler |
1ca26844 ILT |
844 | directives; they bear no relation to physical files. Logical file names help |
845 | error messages reflect the original source file, when @code{@value{AS}} source | |
846 | is itself synthesized from other files. @code{@value{AS}} understands the | |
847 | @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also | |
848 | @ref{File,,@code{.file}}. | |
93b45514 | 849 | |
242d9c06 | 850 | @node Object |
93b45514 | 851 | @section Output (Object) File |
66b818fb RP |
852 | |
853 | @cindex object file | |
854 | @cindex output file | |
855 | @kindex a.out | |
856 | @kindex .o | |
f009d0ab | 857 | Every time you run @code{@value{AS}} it produces an output file, which is |
93b45514 | 858 | your assembly language program translated into numbers. This file |
65fbb2d7 RP |
859 | is the object file. Its default name is |
860 | @ifclear BOUT | |
861 | @code{a.out}. | |
862 | @end ifclear | |
f009d0ab | 863 | @ifset BOUT |
f009d0ab | 864 | @ifset GENERIC |
65fbb2d7 | 865 | @code{a.out}, or |
f009d0ab | 866 | @end ifset |
65fbb2d7 | 867 | @code{b.out} when @code{@value{AS}} is configured for the Intel 80960. |
f009d0ab | 868 | @end ifset |
65fbb2d7 RP |
869 | You can give it another name by using the @code{-o} option. Conventionally, |
870 | object file names end with @file{.o}. The default name is used for historical | |
871 | reasons: older assemblers were capable of assembling self-contained programs | |
872 | directly into a runnable program. (For some formats, this isn't currently | |
873 | possible, but it can be done for the @code{a.out} format.) | |
93b45514 | 874 | |
66b818fb RP |
875 | @cindex linker |
876 | @kindex ld | |
f009d0ab RP |
877 | The object file is meant for input to the linker @code{@value{LD}}. It contains |
878 | assembled program code, information to help @code{@value{LD}} integrate | |
b50e59fe | 879 | the assembled program into a runnable file, and (optionally) symbolic |
d0281557 | 880 | information for the debugger. |
93b45514 | 881 | |
66b818fb | 882 | @c link above to some info file(s) like the description of a.out. |
71dd3c40 | 883 | @c don't forget to describe @sc{gnu} info as well as Unix lossage. |
93b45514 | 884 | |
242d9c06 | 885 | @node Errors |
93b45514 RP |
886 | @section Error and Warning Messages |
887 | ||
66b818fb RP |
888 | @cindex error messsages |
889 | @cindex warning messages | |
3ffb03b1 | 890 | @cindex messages from assembler |
f009d0ab | 891 | @code{@value{AS}} may write warnings and error messages to the standard error |
66b818fb | 892 | file (usually your terminal). This should not happen when a compiler |
f009d0ab RP |
893 | runs @code{@value{AS}} automatically. Warnings report an assumption made so |
894 | that @code{@value{AS}} could keep assembling a flawed program; errors report a | |
b50e59fe | 895 | grave problem that stops the assembly. |
93b45514 | 896 | |
66b818fb | 897 | @cindex format of warning messages |
93b45514 | 898 | Warning messages have the format |
66b818fb | 899 | |
d0281557 | 900 | @smallexample |
b50e59fe | 901 | file_name:@b{NNN}:Warning Message Text |
d0281557 | 902 | @end smallexample |
66b818fb | 903 | |
0b5b143a | 904 | @noindent |
66b818fb | 905 | @cindex line numbers, in warnings/errors |
f009d0ab | 906 | (where @b{NNN} is a line number). If a logical file name has been given |
1ca26844 ILT |
907 | (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of |
908 | the current input file is used. If a logical line number was given | |
f009d0ab RP |
909 | @ifset GENERIC |
910 | (@pxref{Line,,@code{.line}}) | |
911 | @end ifset | |
912 | @ifclear GENERIC | |
913 | @ifclear A29K | |
7a4c8e5c | 914 | (@pxref{Line,,@code{.line}}) |
f009d0ab RP |
915 | @end ifclear |
916 | @ifset A29K | |
7a4c8e5c | 917 | (@pxref{Ln,,@code{.ln}}) |
f009d0ab RP |
918 | @end ifset |
919 | @end ifclear | |
63f5d795 | 920 | then it is used to calculate the number printed, |
b50e59fe RP |
921 | otherwise the actual line in the current source file is printed. The |
922 | message text is intended to be self explanatory (in the grand Unix | |
f009d0ab | 923 | tradition). |
93b45514 | 924 | |
66b818fb | 925 | @cindex format of error messages |
93b45514 | 926 | Error messages have the format |
d0281557 | 927 | @smallexample |
b50e59fe | 928 | file_name:@b{NNN}:FATAL:Error Message Text |
d0281557 | 929 | @end smallexample |
47342e8f | 930 | The file name and line number are derived as for warning |
93b45514 RP |
931 | messages. The actual message text may be rather less explanatory |
932 | because many of them aren't supposed to happen. | |
933 | ||
242d9c06 | 934 | @node Invoking |
7a4c8e5c | 935 | @chapter Command-Line Options |
66b818fb | 936 | |
3ffb03b1 | 937 | @cindex options, all versions of assembler |
66b818fb | 938 | This chapter describes command-line options available in @emph{all} |
8babef85 | 939 | versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific |
f009d0ab RP |
940 | @ifclear GENERIC |
941 | to the @value{TARGET}. | |
942 | @end ifclear | |
943 | @ifset GENERIC | |
0b5b143a | 944 | to particular machine architectures. |
f009d0ab | 945 | @end ifset |
0193302d | 946 | |
71c2d792 DE |
947 | If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2), |
948 | you can use the @samp{-Wa} option to pass arguments through to the assembler. | |
949 | The assembler arguments must be separated from each other (and the @samp{-Wa}) | |
950 | by commas. For example: | |
0193302d KR |
951 | |
952 | @smallexample | |
953 | gcc -c -g -O -Wa,-alh,-L file.c | |
954 | @end smallexample | |
955 | ||
05a0e43b | 956 | @noindent |
71c2d792 DE |
957 | This passes two options to the assembler: @samp{-alh} (emit a listing to |
958 | standard output with with high-level and assembly source) and @samp{-L} (retain | |
959 | local symbols in the symbol table). | |
0193302d | 960 | |
81fcb3ff RP |
961 | Usually you do not need to use this @samp{-Wa} mechanism, since many compiler |
962 | command-line options are automatically passed to the assembler by the compiler. | |
8babef85 | 963 | (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see |
81fcb3ff RP |
964 | precisely what options it passes to each compilation pass, including the |
965 | assembler.) | |
d0281557 | 966 | |
f009d0ab | 967 | @menu |
35cfacf0 | 968 | * a:: -a[cdhlns] enable listings |
f009d0ab RP |
969 | * D:: -D for compatibility |
970 | * f:: -f to work faster | |
971 | * I:: -I for .include search path | |
972 | @ifclear DIFF-TBL-KLUGE | |
973 | * K:: -K for compatibility | |
974 | @end ifclear | |
975 | @ifset DIFF-TBL-KLUGE | |
976 | * K:: -K for difference tables | |
977 | @end ifset | |
978 | ||
979 | * L:: -L to retain local labels | |
79e15b8a | 980 | * M:: -M or --mri to assemble in MRI compatibility mode |
8a51eeaf | 981 | * MD:: --MD for dependency tracking |
f009d0ab RP |
982 | * o:: -o to name the object file |
983 | * R:: -R to join data and text sections | |
62e59d28 | 984 | * statistics:: --statistics to see statistics about assembly |
ef582182 | 985 | * traditional-format:: --traditional-format for compatible output |
f009d0ab RP |
986 | * v:: -v to announce version |
987 | * W:: -W to suppress warnings | |
62e59d28 | 988 | * Z:: -Z to make object file even after errors |
f009d0ab RP |
989 | @end menu |
990 | ||
991 | @node a | |
35cfacf0 | 992 | @section Enable Listings: @code{-a[cdhlns]} |
66b818fb RP |
993 | |
994 | @kindex -a | |
35cfacf0 | 995 | @kindex -ac |
0193302d KR |
996 | @kindex -ad |
997 | @kindex -ah | |
66b818fb | 998 | @kindex -al |
0193302d | 999 | @kindex -an |
66b818fb RP |
1000 | @kindex -as |
1001 | @cindex listings, enabling | |
1002 | @cindex assembly listings, enabling | |
0193302d KR |
1003 | |
1004 | These options enable listing output from the assembler. By itself, | |
1005 | @samp{-a} requests high-level, assembly, and symbols listing. | |
dd565f85 | 1006 | You can use other letters to select specific options for the list: |
0193302d KR |
1007 | @samp{-ah} requests a high-level language listing, |
1008 | @samp{-al} requests an output-program assembly listing, and | |
1009 | @samp{-as} requests a symbol table listing. | |
1010 | High-level listings require that a compiler debugging option like | |
1011 | @samp{-g} be used, and that assembly listings (@samp{-al}) be requested | |
1012 | also. | |
1013 | ||
35cfacf0 ILT |
1014 | Use the @samp{-ac} option to omit false conditionals from a listing. Any lines |
1015 | which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any | |
1016 | other conditional), or a true @code{.if} followed by an @code{.else}, will be | |
1017 | omitted from the listing. | |
1018 | ||
dd565f85 | 1019 | Use the @samp{-ad} option to omit debugging directives from the |
0193302d | 1020 | listing. |
66b818fb RP |
1021 | |
1022 | Once you have specified one of these options, you can further control | |
1023 | listing output and its appearance using the directives @code{.list}, | |
1024 | @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and | |
1025 | @code{.sbttl}. | |
0193302d | 1026 | The @samp{-an} option turns off all forms processing. |
66b818fb RP |
1027 | If you do not request listing output with one of the @samp{-a} options, the |
1028 | listing-control directives have no effect. | |
1029 | ||
0193302d KR |
1030 | The letters after @samp{-a} may be combined into one option, |
1031 | @emph{e.g.}, @samp{-aln}. | |
1032 | ||
f009d0ab | 1033 | @node D |
66b818fb RP |
1034 | @section @code{-D} |
1035 | ||
1036 | @kindex -D | |
b50e59fe | 1037 | This option has no effect whatsoever, but it is accepted to make it more |
05a0e43b | 1038 | likely that scripts written for other assemblers also work with |
f009d0ab | 1039 | @code{@value{AS}}. |
b50e59fe | 1040 | |
f009d0ab | 1041 | @node f |
66b818fb RP |
1042 | @section Work Faster: @code{-f} |
1043 | ||
1044 | @kindex -f | |
1045 | @cindex trusted compiler | |
1046 | @cindex faster processing (@code{-f}) | |
93b45514 | 1047 | @samp{-f} should only be used when assembling programs written by a |
9dcf8057 | 1048 | (trusted) compiler. @samp{-f} stops the assembler from doing whitespace |
05a0e43b RP |
1049 | and comment preprocessing on |
1050 | the input file(s) before assembling them. @xref{Preprocessing, | |
1051 | ,Preprocessing}. | |
66b818fb | 1052 | |
b50e59fe | 1053 | @quotation |
05a0e43b RP |
1054 | @emph{Warning:} if you use @samp{-f} when the files actually need to be |
1055 | preprocessed (if they contain comments, for example), @code{@value{AS}} does | |
1056 | not work correctly. | |
b50e59fe RP |
1057 | @end quotation |
1058 | ||
f009d0ab | 1059 | @node I |
66b818fb RP |
1060 | @section @code{.include} search path: @code{-I} @var{path} |
1061 | ||
1062 | @kindex -I @var{path} | |
1063 | @cindex paths for @code{.include} | |
1064 | @cindex search path for @code{.include} | |
1065 | @cindex @code{include} directive search path | |
d0281557 | 1066 | Use this option to add a @var{path} to the list of directories |
05a0e43b | 1067 | @code{@value{AS}} searches for files specified in @code{.include} |
7a4c8e5c RP |
1068 | directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as |
1069 | many times as necessary to include a variety of paths. The current | |
f009d0ab | 1070 | working directory is always searched first; after that, @code{@value{AS}} |
7a4c8e5c RP |
1071 | searches any @samp{-I} directories in the same order as they were |
1072 | specified (left to right) on the command line. | |
d0281557 | 1073 | |
f009d0ab | 1074 | @node K |
80381063 | 1075 | @section Difference Tables: @code{-K} |
66b818fb | 1076 | |
80381063 | 1077 | @kindex -K |
f009d0ab RP |
1078 | @ifclear DIFF-TBL-KLUGE |
1079 | On the @value{TARGET} family, this option is allowed, but has no effect. It is | |
8babef85 | 1080 | permitted for compatibility with the @sc{gnu} assembler on other platforms, |
d0281557 | 1081 | where it can be used to warn when the assembler alters the machine code |
f009d0ab | 1082 | generated for @samp{.word} directives in difference tables. The @value{TARGET} |
b50e59fe RP |
1083 | family does not have the addressing limitations that sometimes lead to this |
1084 | alteration on other platforms. | |
f009d0ab | 1085 | @end ifclear |
b50e59fe | 1086 | |
f009d0ab | 1087 | @ifset DIFF-TBL-KLUGE |
66b818fb RP |
1088 | @cindex difference tables, warning |
1089 | @cindex warning for altered difference tables | |
f009d0ab | 1090 | @code{@value{AS}} sometimes alters the code emitted for directives of the form |
7a4c8e5c | 1091 | @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}. |
80381063 | 1092 | You can use the @samp{-K} option if you want a warning issued when this |
d0281557 | 1093 | is done. |
f009d0ab | 1094 | @end ifset |
47342e8f | 1095 | |
f009d0ab | 1096 | @node L |
66b818fb RP |
1097 | @section Include Local Labels: @code{-L} |
1098 | ||
1099 | @kindex -L | |
1100 | @cindex local labels, retaining in output | |
b50e59fe | 1101 | Labels beginning with @samp{L} (upper case only) are called @dfn{local |
05a0e43b | 1102 | labels}. @xref{Symbol Names}. Normally you do not see such labels when |
47342e8f | 1103 | debugging, because they are intended for the use of programs (like |
b50e59fe | 1104 | compilers) that compose assembler programs, not for your notice. |
05a0e43b | 1105 | Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not |
b50e59fe | 1106 | normally debug with them. |
93b45514 | 1107 | |
f009d0ab | 1108 | This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols |
93b45514 | 1109 | in the object file. Usually if you do this you also tell the linker |
f009d0ab | 1110 | @code{@value{LD}} to preserve symbols whose names begin with @samp{L}. |
93b45514 | 1111 | |
9dcf8057 JL |
1112 | By default, a local label is any label beginning with @samp{L}, but each |
1113 | target is allowed to redefine the local label prefix. | |
509d5555 JL |
1114 | @ifset HPPA |
1115 | On the HPPA local labels begin with @samp{L$}. | |
1116 | @end ifset | |
3ffb03b1 DE |
1117 | @ifset ARM |
1118 | @samp{;} for the ARM family; | |
99c4053d | 1119 | @end ifset |
9dcf8057 | 1120 | |
79e15b8a ILT |
1121 | @node M |
1122 | @section Assemble in MRI Compatibility Mode: @code{-M} | |
1123 | ||
1124 | @kindex -M | |
1125 | @cindex MRI compatibility mode | |
1126 | The @code{-M} or @code{--mri} option selects MRI compatibility mode. This | |
1127 | changes the syntax and pseudo-op handling of @code{@value{AS}} to make it | |
71dd3c40 ILT |
1128 | compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the |
1129 | configured target) assembler from Microtec Research. The exact nature of the | |
1130 | MRI syntax will not be documented here; see the MRI manuals for more | |
7d99e8af ILT |
1131 | information. Note in particular that the handling of macros and macro |
1132 | arguments is somewhat different. The purpose of this option is to permit | |
1133 | assembling existing MRI assembler code using @code{@value{AS}}. | |
79e15b8a ILT |
1134 | |
1135 | The MRI compatibility is not complete. Certain operations of the MRI assembler | |
1136 | depend upon its object file format, and can not be supported using other object | |
1137 | file formats. Supporting these would require enhancing each object file format | |
1138 | individually. These are: | |
1139 | ||
1140 | @itemize @bullet | |
1141 | @item global symbols in common section | |
1142 | ||
71dd3c40 | 1143 | The m68k MRI assembler supports common sections which are merged by the linker. |
79e15b8a ILT |
1144 | Other object file formats do not support this. @code{@value{AS}} handles |
1145 | common sections by treating them as a single common symbol. It permits local | |
1146 | symbols to be defined within a common section, but it can not support global | |
1147 | symbols, since it has no way to describe them. | |
1148 | ||
1149 | @item complex relocations | |
1150 | ||
71dd3c40 | 1151 | The MRI assemblers support relocations against a negated section address, and |
79e15b8a ILT |
1152 | relocations which combine the start addresses of two or more sections. These |
1153 | are not support by other object file formats. | |
1154 | ||
1155 | @item @code{END} pseudo-op specifying start address | |
1156 | ||
1157 | The MRI @code{END} pseudo-op permits the specification of a start address. | |
1158 | This is not supported by other object file formats. The start address may | |
1159 | instead be specified using the @code{-e} option to the linker, or in a linker | |
1160 | script. | |
1161 | ||
71dd3c40 | 1162 | @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops |
79e15b8a | 1163 | |
71dd3c40 ILT |
1164 | The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module |
1165 | name to the output file. This is not supported by other object file formats. | |
79e15b8a ILT |
1166 | |
1167 | @item @code{ORG} pseudo-op | |
1168 | ||
71dd3c40 ILT |
1169 | The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given |
1170 | address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op, | |
1171 | which changes the location within the current section. Absolute sections are | |
1172 | not supported by other object file formats. The address of a section may be | |
79e15b8a ILT |
1173 | assigned within a linker script. |
1174 | @end itemize | |
1175 | ||
1176 | There are some other features of the MRI assembler which are not supported by | |
1177 | @code{@value{AS}}, typically either because they are difficult or because they | |
1178 | seem of little consequence. Some of these may be supported in future releases. | |
1179 | ||
1180 | @itemize @bullet | |
1181 | ||
79e15b8a ILT |
1182 | @item EBCDIC strings |
1183 | ||
1184 | EBCDIC strings are not supported. | |
1185 | ||
1186 | @item packed binary coded decimal | |
1187 | ||
1188 | Packed binary coded decimal is not supported. This means that the @code{DC.P} | |
1189 | and @code{DCB.P} pseudo-ops are not supported. | |
1190 | ||
1191 | @item @code{FEQU} pseudo-op | |
1192 | ||
71dd3c40 | 1193 | The m68k @code{FEQU} pseudo-op is not supported. |
79e15b8a ILT |
1194 | |
1195 | @item @code{NOOBJ} pseudo-op | |
1196 | ||
71dd3c40 | 1197 | The m68k @code{NOOBJ} pseudo-op is not supported. |
79e15b8a ILT |
1198 | |
1199 | @item @code{OPT} branch control options | |
1200 | ||
71dd3c40 | 1201 | The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, |
79e15b8a ILT |
1202 | @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically |
1203 | relaxes all branches, whether forward or backward, to an appropriate size, so | |
1204 | these options serve no purpose. | |
1205 | ||
1206 | @item @code{OPT} list control options | |
1207 | ||
71dd3c40 | 1208 | The following m68k @code{OPT} list control options are ignored: @code{C}, |
79e15b8a ILT |
1209 | @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, |
1210 | @code{MEX}, @code{MC}, @code{MD}, @code{X}. | |
1211 | ||
1212 | @item other @code{OPT} options | |
1213 | ||
71dd3c40 | 1214 | The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, |
79e15b8a ILT |
1215 | @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. |
1216 | ||
1217 | @item @code{OPT} @code{D} option is default | |
1218 | ||
71dd3c40 | 1219 | The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. |
79e15b8a ILT |
1220 | @code{OPT NOD} may be used to turn it off. |
1221 | ||
1222 | @item @code{XREF} pseudo-op. | |
1223 | ||
71dd3c40 ILT |
1224 | The m68k @code{XREF} pseudo-op is ignored. |
1225 | ||
1226 | @item @code{.debug} pseudo-op | |
1227 | ||
1228 | The i960 @code{.debug} pseudo-op is not supported. | |
1229 | ||
1230 | @item @code{.extended} pseudo-op | |
1231 | ||
1232 | The i960 @code{.extended} pseudo-op is not supported. | |
1233 | ||
1234 | @item @code{.list} pseudo-op. | |
1235 | ||
1236 | The various options of the i960 @code{.list} pseudo-op are not supported. | |
1237 | ||
1238 | @item @code{.optimize} pseudo-op | |
1239 | ||
1240 | The i960 @code{.optimize} pseudo-op is not supported. | |
1241 | ||
1242 | @item @code{.output} pseudo-op | |
1243 | ||
1244 | The i960 @code{.output} pseudo-op is not supported. | |
1245 | ||
1246 | @item @code{.setreal} pseudo-op | |
1247 | ||
1248 | The i960 @code{.setreal} pseudo-op is not supported. | |
79e15b8a | 1249 | |
79e15b8a ILT |
1250 | @end itemize |
1251 | ||
8a51eeaf TT |
1252 | @node MD |
1253 | @section Dependency tracking: @code{--MD} | |
1254 | ||
1255 | @kindex --MD | |
1256 | @cindex dependency tracking | |
1257 | @cindex make rules | |
1258 | ||
1259 | @code{@value{AS}} can generate a dependency file for the file it creates. This | |
1260 | file consists of a single rule suitable for @code{make} describing the | |
1261 | dependencies of the main source file. | |
1262 | ||
1263 | The rule is written to the file named in its argument. | |
1264 | ||
1265 | This feature is used in the automatic updating of makefiles. | |
1266 | ||
f009d0ab | 1267 | @node o |
66b818fb RP |
1268 | @section Name the Object File: @code{-o} |
1269 | ||
1270 | @kindex -o | |
1271 | @cindex naming object file | |
1272 | @cindex object file name | |
f009d0ab | 1273 | There is always one object file output when you run @code{@value{AS}}. By |
9ebc250f | 1274 | default it has the name |
f009d0ab RP |
1275 | @ifset GENERIC |
1276 | @ifset I960 | |
1277 | @file{a.out} (or @file{b.out}, for Intel 960 targets only). | |
1278 | @end ifset | |
1279 | @ifclear I960 | |
9ebc250f | 1280 | @file{a.out}. |
f009d0ab RP |
1281 | @end ifclear |
1282 | @end ifset | |
1283 | @ifclear GENERIC | |
1284 | @ifset I960 | |
9ebc250f | 1285 | @file{b.out}. |
f009d0ab RP |
1286 | @end ifset |
1287 | @ifclear I960 | |
9ebc250f | 1288 | @file{a.out}. |
f009d0ab RP |
1289 | @end ifclear |
1290 | @end ifclear | |
1291 | You use this option (which takes exactly one filename) to give the | |
1292 | object file a different name. | |
93b45514 | 1293 | |
05a0e43b | 1294 | Whatever the object file is called, @code{@value{AS}} overwrites any |
93b45514 RP |
1295 | existing file of the same name. |
1296 | ||
f009d0ab | 1297 | @node R |
66b818fb RP |
1298 | @section Join Data and Text Sections: @code{-R} |
1299 | ||
1300 | @kindex -R | |
1301 | @cindex data and text sections, joining | |
1302 | @cindex text and data sections, joining | |
1303 | @cindex joining text and data sections | |
1304 | @cindex merging text and data sections | |
f009d0ab | 1305 | @code{-R} tells @code{@value{AS}} to write the object file as if all |
24b1493d | 1306 | data-section data lives in the text section. This is only done at |
93b45514 | 1307 | the very last moment: your binary data are the same, but data |
24b1493d | 1308 | section parts are relocated differently. The data section part of |
9ebc250f | 1309 | your object file is zero bytes long because all its bytes are |
24b1493d | 1310 | appended to the text section. (@xref{Sections,,Sections and Relocation}.) |
93b45514 | 1311 | |
b50e59fe | 1312 | When you specify @code{-R} it would be possible to generate shorter |
05a0e43b | 1313 | address displacements (because we do not have to cross between text and |
24b1493d | 1314 | data section). We refrain from doing this simply for compatibility with |
f009d0ab | 1315 | older versions of @code{@value{AS}}. In future, @code{-R} may work this way. |
93b45514 | 1316 | |
f009d0ab RP |
1317 | @ifset COFF |
1318 | When @code{@value{AS}} is configured for COFF output, | |
66b818fb | 1319 | this option is only useful if you use sections named @samp{.text} and |
f009d0ab RP |
1320 | @samp{.data}. |
1321 | @end ifset | |
66b818fb | 1322 | |
9dcf8057 | 1323 | @ifset HPPA |
05a0e43b RP |
1324 | @code{-R} is not supported for any of the HPPA targets. Using |
1325 | @code{-R} generates a warning from @code{@value{AS}}. | |
9dcf8057 JL |
1326 | @end ifset |
1327 | ||
62e59d28 | 1328 | @node statistics |
81fcb3ff | 1329 | @section Display Assembly Statistics: @code{--statistics} |
62e59d28 RP |
1330 | |
1331 | @kindex --statistics | |
1332 | @cindex statistics, about assembly | |
1333 | @cindex time, total for assembly | |
1334 | @cindex space used, maximum for assembly | |
1335 | Use @samp{--statistics} to display two statistics about the resources used by | |
1336 | @code{@value{AS}}: the maximum amount of space allocated during the assembly | |
1337 | (in bytes), and the total execution time taken for the assembly (in @sc{cpu} | |
1338 | seconds). | |
1339 | ||
ef582182 NC |
1340 | @node traditional-format |
1341 | @section Compatible output: @code{--traditional-format} | |
1342 | ||
1343 | @kindex --traditional-format | |
1344 | For some targets, the output of @code{@value{AS}} is different in some ways | |
1345 | from the output of some existing assembler. This switch requests | |
1346 | @code{@value{AS}} to use the traditional format instead. | |
1347 | ||
1348 | For example, it disables the exception frame optimizations which | |
1349 | @code{@value{AS}} normally does by default on @code{@value{GCC}} output. | |
1350 | ||
f009d0ab | 1351 | @node v |
66b818fb RP |
1352 | @section Announce Version: @code{-v} |
1353 | ||
1354 | @kindex -v | |
1355 | @kindex -version | |
3ffb03b1 DE |
1356 | @cindex assembler version |
1357 | @cindex version of assembler | |
7d7ecbdd RP |
1358 | You can find out what version of as is running by including the |
1359 | option @samp{-v} (which you can also spell as @samp{-version}) on the | |
1360 | command line. | |
1361 | ||
f009d0ab | 1362 | @node W |
66b818fb RP |
1363 | @section Suppress Warnings: @code{-W} |
1364 | ||
1365 | @kindex -W | |
1366 | @cindex suppressing warnings | |
1367 | @cindex warnings, suppressing | |
f009d0ab | 1368 | @code{@value{AS}} should never give a warning or error message when |
93b45514 | 1369 | assembling compiler output. But programs written by people often |
f009d0ab | 1370 | cause @code{@value{AS}} to give a warning that a particular assumption was |
93b45514 | 1371 | made. All such warnings are directed to the standard error file. |
47342e8f RP |
1372 | If you use this option, no warnings are issued. This option only |
1373 | affects the warning messages: it does not change any particular of how | |
f009d0ab | 1374 | @code{@value{AS}} assembles your file. Errors, which stop the assembly, are |
93b45514 RP |
1375 | still reported. |
1376 | ||
62e59d28 RP |
1377 | @node Z |
1378 | @section Generate Object File in Spite of Errors: @code{-Z} | |
1379 | @cindex object file, after errors | |
1380 | @cindex errors, continuing after | |
1381 | After an error message, @code{@value{AS}} normally produces no output. If for | |
1382 | some reason you are interested in object file output even after | |
1383 | @code{@value{AS}} gives an error message on your program, use the @samp{-Z} | |
1384 | option. If there are any errors, @code{@value{AS}} continues anyways, and | |
1385 | writes an object file after a final warning message of the form @samp{@var{n} | |
1386 | errors, @var{m} warnings, generating bad object file.} | |
1387 | ||
242d9c06 | 1388 | @node Syntax |
d0281557 | 1389 | @chapter Syntax |
66b818fb RP |
1390 | |
1391 | @cindex machine-independent syntax | |
1392 | @cindex syntax, machine-independent | |
47342e8f | 1393 | This chapter describes the machine-independent syntax allowed in a |
f009d0ab RP |
1394 | source file. @code{@value{AS}} syntax is similar to what many other |
1395 | assemblers use; it is inspired by the BSD 4.2 | |
1396 | @ifclear VAX | |
1397 | assembler. | |
1398 | @end ifclear | |
1399 | @ifset VAX | |
1400 | assembler, except that @code{@value{AS}} does not assemble Vax bit-fields. | |
1401 | @end ifset | |
b50e59fe | 1402 | |
7a4c8e5c | 1403 | @menu |
05a0e43b | 1404 | * Preprocessing:: Preprocessing |
ba487f3a RP |
1405 | * Whitespace:: Whitespace |
1406 | * Comments:: Comments | |
1407 | * Symbol Intro:: Symbols | |
1408 | * Statements:: Statements | |
1409 | * Constants:: Constants | |
7a4c8e5c RP |
1410 | @end menu |
1411 | ||
05a0e43b RP |
1412 | @node Preprocessing |
1413 | @section Preprocessing | |
93b45514 | 1414 | |
66b818fb | 1415 | @cindex preprocessing |
05a0e43b | 1416 | The @code{@value{AS}} internal preprocessor: |
b50e59fe | 1417 | @itemize @bullet |
66b818fb | 1418 | @cindex whitespace, removed by preprocessor |
b50e59fe RP |
1419 | @item |
1420 | adjusts and removes extra whitespace. It leaves one space or tab before | |
1421 | the keywords on a line, and turns any other whitespace on the line into | |
1422 | a single space. | |
93b45514 | 1423 | |
66b818fb | 1424 | @cindex comments, removed by preprocessor |
b50e59fe RP |
1425 | @item |
1426 | removes all comments, replacing them with a single space, or an | |
1427 | appropriate number of newlines. | |
93b45514 | 1428 | |
66b818fb | 1429 | @cindex constants, converted by preprocessor |
b50e59fe RP |
1430 | @item |
1431 | converts character constants into the appropriate numeric values. | |
1432 | @end itemize | |
1433 | ||
dd565f85 | 1434 | It does not do macro processing, include file handling, or |
05a0e43b | 1435 | anything else you may get from your C compiler's preprocessor. You can |
9dcf8057 | 1436 | do include file processing with the @code{.include} directive |
dd565f85 RP |
1437 | (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver |
1438 | to get other ``CPP'' style preprocessing, by giving the input file a | |
1439 | @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of | |
1440 | Output, gcc.info, Using GNU CC}. | |
9dcf8057 | 1441 | |
b50e59fe | 1442 | Excess whitespace, comments, and character constants |
93b45514 | 1443 | cannot be used in the portions of the input text that are not |
05a0e43b | 1444 | preprocessed. |
93b45514 | 1445 | |
66b818fb RP |
1446 | @cindex turning preprocessing on and off |
1447 | @cindex preprocessing, turning on and off | |
1448 | @kindex #NO_APP | |
1449 | @kindex #APP | |
05a0e43b RP |
1450 | If the first line of an input file is @code{#NO_APP} or if you use the |
1451 | @samp{-f} option, whitespace and comments are not removed from the input file. | |
1452 | Within an input file, you can ask for whitespace and comment removal in | |
1453 | specific portions of the by putting a line that says @code{#APP} before the | |
1454 | text that may contain whitespace or comments, and putting a line that says | |
1455 | @code{#NO_APP} after this text. This feature is mainly intend to support | |
1456 | @code{asm} statements in compilers whose output is otherwise free of comments | |
1457 | and whitespace. | |
93b45514 | 1458 | |
242d9c06 | 1459 | @node Whitespace |
93b45514 | 1460 | @section Whitespace |
66b818fb RP |
1461 | |
1462 | @cindex whitespace | |
93b45514 | 1463 | @dfn{Whitespace} is one or more blanks or tabs, in any order. |
7a4c8e5c RP |
1464 | Whitespace is used to separate symbols, and to make programs neater for |
1465 | people to read. Unless within character constants | |
1466 | (@pxref{Characters,,Character Constants}), any whitespace means the same | |
1467 | as exactly one space. | |
93b45514 | 1468 | |
242d9c06 | 1469 | @node Comments |
93b45514 | 1470 | @section Comments |
66b818fb RP |
1471 | |
1472 | @cindex comments | |
f009d0ab | 1473 | There are two ways of rendering comments to @code{@value{AS}}. In both |
93b45514 RP |
1474 | cases the comment is equivalent to one space. |
1475 | ||
d0281557 RP |
1476 | Anything from @samp{/*} through the next @samp{*/} is a comment. |
1477 | This means you may not nest these comments. | |
93b45514 | 1478 | |
d0281557 | 1479 | @smallexample |
93b45514 RP |
1480 | /* |
1481 | The only way to include a newline ('\n') in a comment | |
1482 | is to use this sort of comment. | |
1483 | */ | |
47342e8f | 1484 | |
93b45514 | 1485 | /* This sort of comment does not nest. */ |
d0281557 | 1486 | @end smallexample |
93b45514 | 1487 | |
66b818fb | 1488 | @cindex line comment character |
93b45514 | 1489 | Anything from the @dfn{line comment} character to the next newline |
47342e8f | 1490 | is considered a comment and is ignored. The line comment character is |
910d7df2 C |
1491 | @ifset A29K |
1492 | @samp{;} for the AMD 29K family; | |
1493 | @end ifset | |
99c4053d KR |
1494 | @ifset ARC |
1495 | @samp{;} on the ARC; | |
1496 | @end ifset | |
f009d0ab | 1497 | @ifset H8/300 |
9ebc250f | 1498 | @samp{;} for the H8/300 family; |
f009d0ab RP |
1499 | @end ifset |
1500 | @ifset H8/500 | |
1501 | @samp{!} for the H8/500 family; | |
1502 | @end ifset | |
9dcf8057 JL |
1503 | @ifset HPPA |
1504 | @samp{;} for the HPPA; | |
1505 | @end ifset | |
910d7df2 C |
1506 | @ifset I960 |
1507 | @samp{#} on the i960; | |
1508 | @end ifset | |
f009d0ab RP |
1509 | @ifset SH |
1510 | @samp{!} for the Hitachi SH; | |
1511 | @end ifset | |
910d7df2 C |
1512 | @ifset SPARC |
1513 | @samp{!} on the SPARC; | |
1514 | @end ifset | |
ee73be40 NC |
1515 | @ifset M32R |
1516 | @samp{#} on the m32r; | |
1517 | @end ifset | |
910d7df2 C |
1518 | @ifset M680X0 |
1519 | @samp{|} on the 680x0; | |
1520 | @end ifset | |
1521 | @ifset VAX | |
1522 | @samp{#} on the Vax; | |
1523 | @end ifset | |
f009d0ab | 1524 | @ifset Z8000 |
ba487f3a | 1525 | @samp{!} for the Z8000; |
f009d0ab | 1526 | @end ifset |
68eaa141 NC |
1527 | @ifset V850 |
1528 | @samp{#} on the V850; | |
1529 | @end ifset | |
f009d0ab | 1530 | see @ref{Machine Dependencies}. @refill |
9ebc250f | 1531 | @c FIXME What about i386, m88k, i860? |
09352a5d | 1532 | |
f009d0ab | 1533 | @ifset GENERIC |
b50e59fe | 1534 | On some machines there are two different line comment characters. One |
05a0e43b RP |
1535 | character only begins a comment if it is the first non-whitespace character on |
1536 | a line, while the other always begins a comment. | |
f009d0ab | 1537 | @end ifset |
93b45514 | 1538 | |
68eaa141 NC |
1539 | @ifset V850 |
1540 | The V850 assembler also supports a double dash as starting a comment that | |
1541 | extends to the end of the line. | |
1542 | ||
1543 | @samp{--}; | |
1544 | @end ifset | |
68eaa141 | 1545 | |
66b818fb RP |
1546 | @kindex # |
1547 | @cindex lines starting with @code{#} | |
1548 | @cindex logical line numbers | |
dd565f85 RP |
1549 | To be compatible with past assemblers, lines that begin with @samp{#} have a |
1550 | special interpretation. Following the @samp{#} should be an absolute | |
05a0e43b | 1551 | expression (@pxref{Expressions}): the logical line number of the @emph{next} |
dd565f85 RP |
1552 | line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a |
1553 | new logical file name. The rest of the line, if any, should be whitespace. | |
93b45514 RP |
1554 | |
1555 | If the first non-whitespace characters on the line are not numeric, | |
1556 | the line is ignored. (Just like a comment.) | |
dd565f85 | 1557 | |
d0281557 | 1558 | @smallexample |
93b45514 RP |
1559 | # This is an ordinary comment. |
1560 | # 42-6 "new_file_name" # New logical file name | |
1561 | # This is logical line # 36. | |
d0281557 | 1562 | @end smallexample |
93b45514 | 1563 | This feature is deprecated, and may disappear from future versions |
f009d0ab | 1564 | of @code{@value{AS}}. |
93b45514 | 1565 | |
242d9c06 | 1566 | @node Symbol Intro |
93b45514 | 1567 | @section Symbols |
66b818fb | 1568 | |
66b818fb | 1569 | @cindex characters used in symbols |
f009d0ab RP |
1570 | @ifclear SPECIAL-SYMS |
1571 | A @dfn{symbol} is one or more characters chosen from the set of all | |
1572 | letters (both upper and lower case), digits and the three characters | |
1573 | @samp{_.$}. | |
1574 | @end ifclear | |
1575 | @ifset SPECIAL-SYMS | |
1576 | @ifclear GENERIC | |
1577 | @ifset H8 | |
93b45514 | 1578 | A @dfn{symbol} is one or more characters chosen from the set of all |
f009d0ab RP |
1579 | letters (both upper and lower case), digits and the three characters |
1580 | @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in | |
1581 | symbol names.) | |
1582 | @end ifset | |
1583 | @end ifclear | |
1584 | @end ifset | |
1585 | @ifset GENERIC | |
24b1493d | 1586 | On most machines, you can also use @code{$} in symbol names; exceptions |
f009d0ab RP |
1587 | are noted in @ref{Machine Dependencies}. |
1588 | @end ifset | |
24b1493d | 1589 | No symbol may begin with a digit. Case is significant. |
b50e59fe RP |
1590 | There is no length limit: all characters are significant. Symbols are |
1591 | delimited by characters not in that set, or by the beginning of a file | |
1592 | (since the source program must end with a newline, the end of a file is | |
1593 | not a possible symbol delimiter). @xref{Symbols}. | |
66b818fb | 1594 | @cindex length of symbols |
93b45514 | 1595 | |
242d9c06 | 1596 | @node Statements |
93b45514 | 1597 | @section Statements |
66b818fb RP |
1598 | |
1599 | @cindex statements, structure of | |
1600 | @cindex line separator character | |
1601 | @cindex statement separator character | |
f009d0ab RP |
1602 | @ifclear GENERIC |
1603 | @ifclear abnormal-separator | |
d0281557 RP |
1604 | A @dfn{statement} ends at a newline character (@samp{\n}) or at a |
1605 | semicolon (@samp{;}). The newline or semicolon is considered part of | |
1606 | the preceding statement. Newlines and semicolons within character | |
05a0e43b | 1607 | constants are an exception: they do not end statements. |
f009d0ab RP |
1608 | @end ifclear |
1609 | @ifset abnormal-separator | |
1610 | @ifset A29K | |
d0281557 RP |
1611 | A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at'' |
1612 | sign (@samp{@@}). The newline or at sign is considered part of the | |
1613 | preceding statement. Newlines and at signs within character constants | |
05a0e43b | 1614 | are an exception: they do not end statements. |
f009d0ab | 1615 | @end ifset |
9dcf8057 JL |
1616 | @ifset HPPA |
1617 | A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation | |
1618 | point (@samp{!}). The newline or exclamation point is considered part of the | |
1619 | preceding statement. Newlines and exclamation points within character | |
05a0e43b | 1620 | constants are an exception: they do not end statements. |
9dcf8057 | 1621 | @end ifset |
f009d0ab RP |
1622 | @ifset H8 |
1623 | A @dfn{statement} ends at a newline character (@samp{\n}); or (for the | |
1624 | H8/300) a dollar sign (@samp{$}); or (for the | |
f009d0ab | 1625 | Hitachi-SH or the |
f009d0ab RP |
1626 | H8/500) a semicolon |
1627 | (@samp{;}). The newline or separator character is considered part of | |
1628 | the preceding statement. Newlines and separators within character | |
05a0e43b | 1629 | constants are an exception: they do not end statements. |
f009d0ab RP |
1630 | @end ifset |
1631 | @end ifset | |
1632 | @end ifclear | |
1633 | @ifset GENERIC | |
24b1493d RP |
1634 | A @dfn{statement} ends at a newline character (@samp{\n}) or line |
1635 | separator character. (The line separator is usually @samp{;}, unless | |
f009d0ab | 1636 | this conflicts with the comment character; @pxref{Machine Dependencies}.) The |
24b1493d RP |
1637 | newline or separator character is considered part of the preceding |
1638 | statement. Newlines and separators within character constants are an | |
05a0e43b | 1639 | exception: they do not end statements. |
f009d0ab | 1640 | @end ifset |
d0281557 | 1641 | |
66b818fb RP |
1642 | @cindex newline, required at file end |
1643 | @cindex EOF, newline must precede | |
93b45514 | 1644 | It is an error to end any statement with end-of-file: the last |
b50e59fe | 1645 | character of any input file should be a newline.@refill |
93b45514 | 1646 | |
47342e8f | 1647 | An empty statement is allowed, and may include whitespace. It is ignored. |
93b45514 | 1648 | |
66b818fb RP |
1649 | @cindex instructions and directives |
1650 | @cindex directives and instructions | |
b50e59fe | 1651 | @c "key symbol" is not used elsewhere in the document; seems pedantic to |
71dd3c40 | 1652 | @c @defn{} it in that case, as was done previously... doc@cygnus.com, |
d0281557 | 1653 | @c 13feb91. |
47342e8f | 1654 | A statement begins with zero or more labels, optionally followed by a |
b50e59fe | 1655 | key symbol which determines what kind of statement it is. The key |
93b45514 | 1656 | symbol determines the syntax of the rest of the statement. If the |
b50e59fe | 1657 | symbol begins with a dot @samp{.} then the statement is an assembler |
47342e8f RP |
1658 | directive: typically valid for any computer. If the symbol begins with |
1659 | a letter the statement is an assembly language @dfn{instruction}: it | |
05a0e43b | 1660 | assembles into a machine language instruction. |
f009d0ab | 1661 | @ifset GENERIC |
05a0e43b | 1662 | Different versions of @code{@value{AS}} for different computers |
d0281557 RP |
1663 | recognize different instructions. In fact, the same symbol may |
1664 | represent a different instruction in a different computer's assembly | |
1665 | language.@refill | |
f009d0ab | 1666 | @end ifset |
47342e8f | 1667 | |
66b818fb RP |
1668 | @cindex @code{:} (label) |
1669 | @cindex label (@code{:}) | |
d0281557 | 1670 | A label is a symbol immediately followed by a colon (@code{:}). |
47342e8f | 1671 | Whitespace before a label or after a colon is permitted, but you may not |
d0281557 | 1672 | have whitespace between a label's symbol and its colon. @xref{Labels}. |
93b45514 | 1673 | |
9dcf8057 JL |
1674 | @ifset HPPA |
1675 | For HPPA targets, labels need not be immediately followed by a colon, but | |
1676 | the definition of a label must begin in column zero. This also implies that | |
1677 | only one label may be defined on each line. | |
1678 | @end ifset | |
1679 | ||
d0281557 | 1680 | @smallexample |
93b45514 | 1681 | label: .directive followed by something |
24b1493d | 1682 | another_label: # This is an empty statement. |
93b45514 | 1683 | instruction operand_1, operand_2, @dots{} |
d0281557 | 1684 | @end smallexample |
93b45514 | 1685 | |
242d9c06 | 1686 | @node Constants |
93b45514 | 1687 | @section Constants |
66b818fb RP |
1688 | |
1689 | @cindex constants | |
93b45514 RP |
1690 | A constant is a number, written so that its value is known by |
1691 | inspection, without knowing any context. Like this: | |
f4335d56 | 1692 | @smallexample |
f009d0ab | 1693 | @group |
93b45514 RP |
1694 | .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. |
1695 | .ascii "Ring the bell\7" # A string constant. | |
1696 | .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. | |
1697 | .float 0f-314159265358979323846264338327\ | |
1698 | 95028841971.693993751E-40 # - pi, a flonum. | |
f009d0ab | 1699 | @end group |
f4335d56 | 1700 | @end smallexample |
93b45514 | 1701 | |
7a4c8e5c | 1702 | @menu |
ba487f3a RP |
1703 | * Characters:: Character Constants |
1704 | * Numbers:: Number Constants | |
7a4c8e5c RP |
1705 | @end menu |
1706 | ||
242d9c06 | 1707 | @node Characters |
93b45514 | 1708 | @subsection Character Constants |
66b818fb RP |
1709 | |
1710 | @cindex character constants | |
1711 | @cindex constants, character | |
47342e8f RP |
1712 | There are two kinds of character constants. A @dfn{character} stands |
1713 | for one character in one byte and its value may be used in | |
93b45514 | 1714 | numeric expressions. String constants (properly called string |
47342e8f | 1715 | @emph{literals}) are potentially many bytes and their values may not be |
93b45514 RP |
1716 | used in arithmetic expressions. |
1717 | ||
7a4c8e5c | 1718 | @menu |
ba487f3a RP |
1719 | * Strings:: Strings |
1720 | * Chars:: Characters | |
7a4c8e5c RP |
1721 | @end menu |
1722 | ||
242d9c06 | 1723 | @node Strings |
93b45514 | 1724 | @subsubsection Strings |
66b818fb RP |
1725 | |
1726 | @cindex string constants | |
1727 | @cindex constants, string | |
93b45514 | 1728 | A @dfn{string} is written between double-quotes. It may contain |
47342e8f | 1729 | double-quotes or null characters. The way to get special characters |
93b45514 | 1730 | into a string is to @dfn{escape} these characters: precede them with |
b50e59fe | 1731 | a backslash @samp{\} character. For example @samp{\\} represents |
93b45514 | 1732 | one backslash: the first @code{\} is an escape which tells |
f009d0ab RP |
1733 | @code{@value{AS}} to interpret the second character literally as a backslash |
1734 | (which prevents @code{@value{AS}} from recognizing the second @code{\} as an | |
93b45514 RP |
1735 | escape character). The complete list of escapes follows. |
1736 | ||
66b818fb RP |
1737 | @cindex escape codes, character |
1738 | @cindex character escape codes | |
93b45514 | 1739 | @table @kbd |
ba487f3a RP |
1740 | @c @item \a |
1741 | @c Mnemonic for ACKnowledge; for ASCII this is octal code 007. | |
66b818fb | 1742 | @c |
66b818fb RP |
1743 | @cindex @code{\b} (backspace character) |
1744 | @cindex backspace (@code{\b}) | |
71dd3c40 | 1745 | @item \b |
93b45514 | 1746 | Mnemonic for backspace; for ASCII this is octal code 010. |
66b818fb | 1747 | |
ba487f3a RP |
1748 | @c @item \e |
1749 | @c Mnemonic for EOText; for ASCII this is octal code 004. | |
66b818fb | 1750 | @c |
66b818fb RP |
1751 | @cindex @code{\f} (formfeed character) |
1752 | @cindex formfeed (@code{\f}) | |
71dd3c40 | 1753 | @item \f |
93b45514 | 1754 | Mnemonic for FormFeed; for ASCII this is octal code 014. |
66b818fb | 1755 | |
66b818fb RP |
1756 | @cindex @code{\n} (newline character) |
1757 | @cindex newline (@code{\n}) | |
71dd3c40 | 1758 | @item \n |
93b45514 | 1759 | Mnemonic for newline; for ASCII this is octal code 012. |
66b818fb | 1760 | |
ba487f3a RP |
1761 | @c @item \p |
1762 | @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. | |
66b818fb | 1763 | @c |
66b818fb RP |
1764 | @cindex @code{\r} (carriage return character) |
1765 | @cindex carriage return (@code{\r}) | |
71dd3c40 | 1766 | @item \r |
93b45514 | 1767 | Mnemonic for carriage-Return; for ASCII this is octal code 015. |
66b818fb | 1768 | |
ba487f3a RP |
1769 | @c @item \s |
1770 | @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with | |
1771 | @c other assemblers. | |
66b818fb | 1772 | @c |
66b818fb RP |
1773 | @cindex @code{\t} (tab) |
1774 | @cindex tab (@code{\t}) | |
71dd3c40 | 1775 | @item \t |
93b45514 | 1776 | Mnemonic for horizontal Tab; for ASCII this is octal code 011. |
66b818fb | 1777 | |
ba487f3a RP |
1778 | @c @item \v |
1779 | @c Mnemonic for Vertical tab; for ASCII this is octal code 013. | |
1780 | @c @item \x @var{digit} @var{digit} @var{digit} | |
1781 | @c A hexadecimal character code. The numeric code is 3 hexadecimal digits. | |
66b818fb | 1782 | @c |
66b818fb RP |
1783 | @cindex @code{\@var{ddd}} (octal character code) |
1784 | @cindex octal character code (@code{\@var{ddd}}) | |
71dd3c40 | 1785 | @item \ @var{digit} @var{digit} @var{digit} |
93b45514 | 1786 | An octal character code. The numeric code is 3 octal digits. |
47342e8f RP |
1787 | For compatibility with other Unix systems, 8 and 9 are accepted as digits: |
1788 | for example, @code{\008} has the value 010, and @code{\009} the value 011. | |
66b818fb | 1789 | |
910d7df2 C |
1790 | @cindex @code{\@var{xd...}} (hex character code) |
1791 | @cindex hex character code (@code{\@var{xd...}}) | |
1792 | @item \@code{x} @var{hex-digits...} | |
1793 | A hex character code. All trailing hex digits are combined. Either upper or | |
1794 | lower case @code{x} works. | |
9dcf8057 | 1795 | |
66b818fb RP |
1796 | @cindex @code{\\} (@samp{\} character) |
1797 | @cindex backslash (@code{\\}) | |
71dd3c40 | 1798 | @item \\ |
93b45514 | 1799 | Represents one @samp{\} character. |
66b818fb | 1800 | |
ba487f3a RP |
1801 | @c @item \' |
1802 | @c Represents one @samp{'} (accent acute) character. | |
1803 | @c This is needed in single character literals | |
7a4c8e5c | 1804 | @c (@xref{Characters,,Character Constants}.) to represent |
ba487f3a | 1805 | @c a @samp{'}. |
66b818fb | 1806 | @c |
66b818fb RP |
1807 | @cindex @code{\"} (doublequote character) |
1808 | @cindex doublequote (@code{\"}) | |
71dd3c40 | 1809 | @item \" |
93b45514 RP |
1810 | Represents one @samp{"} character. Needed in strings to represent |
1811 | this character, because an unescaped @samp{"} would end the string. | |
66b818fb | 1812 | |
93b45514 | 1813 | @item \ @var{anything-else} |
05a0e43b | 1814 | Any other character when escaped by @kbd{\} gives a warning, but |
dd565f85 | 1815 | assembles as if the @samp{\} was not present. The idea is that if |
93b45514 | 1816 | you used an escape sequence you clearly didn't want the literal |
f009d0ab RP |
1817 | interpretation of the following character. However @code{@value{AS}} has no |
1818 | other interpretation, so @code{@value{AS}} knows it is giving you the wrong | |
93b45514 RP |
1819 | code and warns you of the fact. |
1820 | @end table | |
1821 | ||
1822 | Which characters are escapable, and what those escapes represent, | |
1823 | varies widely among assemblers. The current set is what we think | |
d0281557 | 1824 | the BSD 4.2 assembler recognizes, and is a subset of what most C |
05a0e43b | 1825 | compilers recognize. If you are in doubt, do not use an escape |
93b45514 RP |
1826 | sequence. |
1827 | ||
242d9c06 | 1828 | @node Chars |
93b45514 | 1829 | @subsubsection Characters |
66b818fb RP |
1830 | |
1831 | @cindex single character constant | |
1832 | @cindex character, single | |
1833 | @cindex constant, single character | |
93b45514 RP |
1834 | A single character may be written as a single quote immediately |
1835 | followed by that character. The same escapes apply to characters as | |
1836 | to strings. So if you want to write the character backslash, you | |
1837 | must write @kbd{'\\} where the first @code{\} escapes the second | |
b50e59fe | 1838 | @code{\}. As you can see, the quote is an acute accent, not a |
d0281557 | 1839 | grave accent. A newline |
f009d0ab RP |
1840 | @ifclear GENERIC |
1841 | @ifclear abnormal-separator | |
09352a5d | 1842 | (or semicolon @samp{;}) |
f009d0ab RP |
1843 | @end ifclear |
1844 | @ifset abnormal-separator | |
1845 | @ifset A29K | |
b50e59fe | 1846 | (or at sign @samp{@@}) |
f009d0ab RP |
1847 | @end ifset |
1848 | @ifset H8 | |
1849 | (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the | |
f009d0ab | 1850 | Hitachi SH or |
f009d0ab RP |
1851 | H8/500) |
1852 | @end ifset | |
1853 | @end ifset | |
1854 | @end ifclear | |
d0281557 RP |
1855 | immediately following an acute accent is taken as a literal character |
1856 | and does not count as the end of a statement. The value of a character | |
93b45514 | 1857 | constant in a numeric expression is the machine's byte-wide code for |
f009d0ab | 1858 | that character. @code{@value{AS}} assumes your character code is ASCII: |
d0281557 | 1859 | @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill |
93b45514 | 1860 | |
242d9c06 | 1861 | @node Numbers |
93b45514 | 1862 | @subsection Number Constants |
66b818fb RP |
1863 | |
1864 | @cindex constants, number | |
1865 | @cindex number constants | |
f009d0ab | 1866 | @code{@value{AS}} distinguishes three kinds of numbers according to how they |
47342e8f RP |
1867 | are stored in the target machine. @emph{Integers} are numbers that |
1868 | would fit into an @code{int} in the C language. @emph{Bignums} are | |
d0281557 | 1869 | integers, but they are stored in more than 32 bits. @emph{Flonums} |
93b45514 RP |
1870 | are floating point numbers, described below. |
1871 | ||
7a4c8e5c | 1872 | @menu |
ba487f3a RP |
1873 | * Integers:: Integers |
1874 | * Bignums:: Bignums | |
1875 | * Flonums:: Flonums | |
f009d0ab RP |
1876 | @ifclear GENERIC |
1877 | @ifset I960 | |
ba487f3a | 1878 | * Bit Fields:: Bit Fields |
f009d0ab RP |
1879 | @end ifset |
1880 | @end ifclear | |
7a4c8e5c RP |
1881 | @end menu |
1882 | ||
242d9c06 | 1883 | @node Integers |
93b45514 | 1884 | @subsubsection Integers |
66b818fb RP |
1885 | @cindex integers |
1886 | @cindex constants, integer | |
1887 | ||
1888 | @cindex binary integers | |
1889 | @cindex integers, binary | |
b50e59fe RP |
1890 | A binary integer is @samp{0b} or @samp{0B} followed by zero or more of |
1891 | the binary digits @samp{01}. | |
1892 | ||
66b818fb RP |
1893 | @cindex octal integers |
1894 | @cindex integers, octal | |
93b45514 RP |
1895 | An octal integer is @samp{0} followed by zero or more of the octal |
1896 | digits (@samp{01234567}). | |
1897 | ||
66b818fb RP |
1898 | @cindex decimal integers |
1899 | @cindex integers, decimal | |
93b45514 RP |
1900 | A decimal integer starts with a non-zero digit followed by zero or |
1901 | more digits (@samp{0123456789}). | |
1902 | ||
66b818fb RP |
1903 | @cindex hexadecimal integers |
1904 | @cindex integers, hexadecimal | |
93b45514 RP |
1905 | A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or |
1906 | more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. | |
1907 | ||
47342e8f | 1908 | Integers have the usual values. To denote a negative integer, use |
b50e59fe | 1909 | the prefix operator @samp{-} discussed under expressions |
7a4c8e5c | 1910 | (@pxref{Prefix Ops,,Prefix Operators}). |
93b45514 | 1911 | |
242d9c06 | 1912 | @node Bignums |
93b45514 | 1913 | @subsubsection Bignums |
66b818fb RP |
1914 | |
1915 | @cindex bignums | |
1916 | @cindex constants, bignum | |
93b45514 RP |
1917 | A @dfn{bignum} has the same syntax and semantics as an integer |
1918 | except that the number (or its negative) takes more than 32 bits to | |
1919 | represent in binary. The distinction is made because in some places | |
1920 | integers are permitted while bignums are not. | |
1921 | ||
242d9c06 | 1922 | @node Flonums |
93b45514 | 1923 | @subsubsection Flonums |
66b818fb RP |
1924 | @cindex flonums |
1925 | @cindex floating point numbers | |
1926 | @cindex constants, floating point | |
1927 | ||
1928 | @cindex precision, floating point | |
b50e59fe | 1929 | A @dfn{flonum} represents a floating point number. The translation is |
66b818fb | 1930 | indirect: a decimal floating point number from the text is converted by |
f009d0ab | 1931 | @code{@value{AS}} to a generic binary floating point number of more than |
b50e59fe RP |
1932 | sufficient precision. This generic floating point number is converted |
1933 | to a particular computer's floating point format (or formats) by a | |
f009d0ab | 1934 | portion of @code{@value{AS}} specialized to that computer. |
93b45514 RP |
1935 | |
1936 | A flonum is written by writing (in order) | |
1937 | @itemize @bullet | |
1938 | @item | |
1939 | The digit @samp{0}. | |
9dcf8057 | 1940 | @ifset HPPA |
05a0e43b | 1941 | (@samp{0} is optional on the HPPA.) |
9dcf8057 | 1942 | @end ifset |
f009d0ab | 1943 | |
93b45514 | 1944 | @item |
f009d0ab RP |
1945 | A letter, to tell @code{@value{AS}} the rest of the number is a flonum. |
1946 | @ifset GENERIC | |
66b818fb | 1947 | @kbd{e} is recommended. Case is not important. |
0b5b143a RP |
1948 | @ignore |
1949 | @c FIXME: verify if flonum syntax really this vague for most cases | |
05a0e43b RP |
1950 | (Any otherwise illegal letter works here, but that might be changed. Vax BSD |
1951 | 4.2 assembler seems to allow any of @samp{defghDEFGH}.) | |
0b5b143a | 1952 | @end ignore |
f009d0ab RP |
1953 | |
1954 | On the H8/300, H8/500, | |
f009d0ab | 1955 | Hitachi SH, |
f009d0ab RP |
1956 | and AMD 29K architectures, the letter must be |
1957 | one of the letters @samp{DFPRSX} (in upper or lower case). | |
1958 | ||
3ffb03b1 | 1959 | On the ARC, the letter must be one of the letters @samp{DFRS} |
99c4053d | 1960 | (in upper or lower case). |
99c4053d | 1961 | |
f009d0ab RP |
1962 | On the Intel 960 architecture, the letter must be |
1963 | one of the letters @samp{DFT} (in upper or lower case). | |
9dcf8057 JL |
1964 | |
1965 | On the HPPA architecture, the letter must be @samp{E} (upper case only). | |
f009d0ab RP |
1966 | @end ifset |
1967 | @ifclear GENERIC | |
1968 | @ifset A29K | |
66b818fb | 1969 | One of the letters @samp{DFPRSX} (in upper or lower case). |
f009d0ab | 1970 | @end ifset |
99c4053d KR |
1971 | @ifset ARC |
1972 | One of the letters @samp{DFRS} (in upper or lower case). | |
1973 | @end ifset | |
f009d0ab RP |
1974 | @ifset H8 |
1975 | One of the letters @samp{DFPRSX} (in upper or lower case). | |
1976 | @end ifset | |
9dcf8057 | 1977 | @ifset HPPA |
05a0e43b | 1978 | The letter @samp{E} (upper case only). |
9dcf8057 | 1979 | @end ifset |
910d7df2 C |
1980 | @ifset I960 |
1981 | One of the letters @samp{DFT} (in upper or lower case). | |
1982 | @end ifset | |
f009d0ab RP |
1983 | @end ifclear |
1984 | ||
93b45514 RP |
1985 | @item |
1986 | An optional sign: either @samp{+} or @samp{-}. | |
f009d0ab | 1987 | |
93b45514 | 1988 | @item |
47342e8f | 1989 | An optional @dfn{integer part}: zero or more decimal digits. |
f009d0ab | 1990 | |
93b45514 | 1991 | @item |
66b818fb | 1992 | An optional @dfn{fractional part}: @samp{.} followed by zero |
93b45514 | 1993 | or more decimal digits. |
f009d0ab | 1994 | |
93b45514 RP |
1995 | @item |
1996 | An optional exponent, consisting of: | |
f009d0ab | 1997 | |
93b45514 RP |
1998 | @itemize @bullet |
1999 | @item | |
b50e59fe | 2000 | An @samp{E} or @samp{e}. |
d0281557 RP |
2001 | @c I can't find a config where "EXP_CHARS" is other than 'eE', but in |
2002 | @c principle this can perfectly well be different on different targets. | |
93b45514 RP |
2003 | @item |
2004 | Optional sign: either @samp{+} or @samp{-}. | |
2005 | @item | |
2006 | One or more decimal digits. | |
2007 | @end itemize | |
f009d0ab | 2008 | |
93b45514 RP |
2009 | @end itemize |
2010 | ||
66b818fb | 2011 | At least one of the integer part or the fractional part must be |
47342e8f | 2012 | present. The floating point number has the usual base-10 value. |
93b45514 | 2013 | |
f009d0ab | 2014 | @code{@value{AS}} does all processing using integers. Flonums are computed |
47342e8f | 2015 | independently of any floating point hardware in the computer running |
f009d0ab | 2016 | @code{@value{AS}}. |
d0281557 | 2017 | |
f009d0ab RP |
2018 | @ifclear GENERIC |
2019 | @ifset I960 | |
d0281557 RP |
2020 | @c Bit fields are written as a general facility but are also controlled |
2021 | @c by a conditional-compilation flag---which is as of now (21mar91) | |
2022 | @c turned on only by the i960 config of GAS. | |
242d9c06 | 2023 | @node Bit Fields |
d0281557 | 2024 | @subsubsection Bit Fields |
66b818fb RP |
2025 | |
2026 | @cindex bit fields | |
2027 | @cindex constants, bit field | |
d0281557 RP |
2028 | You can also define numeric constants as @dfn{bit fields}. |
2029 | specify two numbers separated by a colon--- | |
2030 | @example | |
2031 | @var{mask}:@var{value} | |
2032 | @end example | |
2033 | @noindent | |
05a0e43b RP |
2034 | @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and |
2035 | @var{value}. | |
d0281557 RP |
2036 | |
2037 | The resulting number is then packed | |
f009d0ab | 2038 | @ifset GENERIC |
7a4c8e5c | 2039 | @c this conditional paren in case bit fields turned on elsewhere than 960 |
d0281557 | 2040 | (in host-dependent byte order) |
f009d0ab | 2041 | @end ifset |
d0281557 RP |
2042 | into a field whose width depends on which assembler directive has the |
2043 | bit-field as its argument. Overflow (a result from the bitwise and | |
2044 | requiring more binary digits to represent) is not an error; instead, | |
2045 | more constants are generated, of the specified width, beginning with the | |
2046 | least significant digits.@refill | |
2047 | ||
2048 | The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, | |
2049 | @code{.short}, and @code{.word} accept bit-field arguments. | |
f009d0ab RP |
2050 | @end ifset |
2051 | @end ifclear | |
93b45514 | 2052 | |
242d9c06 | 2053 | @node Sections |
24b1493d | 2054 | @chapter Sections and Relocation |
66b818fb RP |
2055 | @cindex sections |
2056 | @cindex relocation | |
d0281557 | 2057 | |
7a4c8e5c | 2058 | @menu |
ba487f3a | 2059 | * Secs Background:: Background |
3ffb03b1 DE |
2060 | * Ld Sections:: Linker Sections |
2061 | * As Sections:: Assembler Internal Sections | |
ba487f3a RP |
2062 | * Sub-Sections:: Sub-Sections |
2063 | * bss:: bss Section | |
7a4c8e5c RP |
2064 | @end menu |
2065 | ||
242d9c06 | 2066 | @node Secs Background |
b50e59fe | 2067 | @section Background |
66b818fb | 2068 | |
24b1493d | 2069 | Roughly, a section is a range of addresses, with no gaps; all data |
d0281557 | 2070 | ``in'' those addresses is treated the same for some particular purpose. |
24b1493d | 2071 | For example there may be a ``read only'' section. |
93b45514 | 2072 | |
66b818fb RP |
2073 | @cindex linker, and assembler |
2074 | @cindex assembler, and linker | |
f009d0ab RP |
2075 | The linker @code{@value{LD}} reads many object files (partial programs) and |
2076 | combines their contents to form a runnable program. When @code{@value{AS}} | |
05a0e43b RP |
2077 | emits an object file, the partial program is assumed to start at address 0. |
2078 | @code{@value{LD}} assigns the final addresses for the partial program, so that | |
2079 | different partial programs do not overlap. This is actually an | |
2080 | oversimplification, but it suffices to explain how @code{@value{AS}} uses | |
2081 | sections. | |
93b45514 | 2082 | |
f009d0ab | 2083 | @code{@value{LD}} moves blocks of bytes of your program to their run-time |
93b45514 | 2084 | addresses. These blocks slide to their run-time addresses as rigid |
47342e8f | 2085 | units; their length does not change and neither does the order of bytes |
24b1493d RP |
2086 | within them. Such a rigid unit is called a @emph{section}. Assigning |
2087 | run-time addresses to sections is called @dfn{relocation}. It includes | |
47342e8f | 2088 | the task of adjusting mentions of object-file addresses so they refer to |
d0281557 | 2089 | the proper run-time addresses. |
f009d0ab RP |
2090 | @ifset H8 |
2091 | For the H8/300 and H8/500, | |
f009d0ab | 2092 | and for the Hitachi SH, |
f009d0ab RP |
2093 | @code{@value{AS}} pads sections if needed to |
2094 | ensure they end on a word (sixteen bit) boundary. | |
2095 | @end ifset | |
2096 | ||
3ffb03b1 | 2097 | @cindex standard assembler sections |
f009d0ab | 2098 | An object file written by @code{@value{AS}} has at least three sections, any |
24b1493d | 2099 | of which may be empty. These are named @dfn{text}, @dfn{data} and |
f009d0ab | 2100 | @dfn{bss} sections. |
93b45514 | 2101 | |
f009d0ab RP |
2102 | @ifset COFF |
2103 | @ifset GENERIC | |
2104 | When it generates COFF output, | |
2105 | @end ifset | |
2106 | @code{@value{AS}} can also generate whatever other named sections you specify | |
24b1493d | 2107 | using the @samp{.section} directive (@pxref{Section,,@code{.section}}). |
05a0e43b RP |
2108 | If you do not use any directives that place output in the @samp{.text} |
2109 | or @samp{.data} sections, these sections still exist, but are empty. | |
f009d0ab | 2110 | @end ifset |
d0281557 | 2111 | |
9dcf8057 JL |
2112 | @ifset HPPA |
2113 | @ifset GENERIC | |
2114 | When @code{@value{AS}} generates SOM or ELF output for the HPPA, | |
2115 | @end ifset | |
2116 | @code{@value{AS}} can also generate whatever other named sections you | |
2117 | specify using the @samp{.space} and @samp{.subspace} directives. See | |
2118 | @cite{HP9000 Series 800 Assembly Language Reference Manual} | |
2119 | (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} | |
2120 | assembler directives. | |
2121 | ||
2122 | @ifset SOM | |
2123 | Additionally, @code{@value{AS}} uses different names for the standard | |
2124 | text, data, and bss sections when generating SOM output. Program text | |
2125 | is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and | |
2126 | BSS into @samp{$BSS$}. | |
2127 | @end ifset | |
2128 | @end ifset | |
2129 | ||
24b1493d RP |
2130 | Within the object file, the text section starts at address @code{0}, the |
2131 | data section follows, and the bss section follows the data section. | |
d0281557 | 2132 | |
9dcf8057 JL |
2133 | @ifset HPPA |
2134 | When generating either SOM or ELF output files on the HPPA, the text | |
2135 | section starts at address @code{0}, the data section at address | |
2136 | @code{0x4000000}, and the bss section follows the data section. | |
2137 | @end ifset | |
2138 | ||
05a0e43b | 2139 | To let @code{@value{LD}} know which data changes when the sections are |
f009d0ab | 2140 | relocated, and how to change that data, @code{@value{AS}} also writes to the |
93b45514 | 2141 | object file details of the relocation needed. To perform relocation |
f009d0ab | 2142 | @code{@value{LD}} must know, each time an address in the object |
47342e8f | 2143 | file is mentioned: |
93b45514 RP |
2144 | @itemize @bullet |
2145 | @item | |
47342e8f RP |
2146 | Where in the object file is the beginning of this reference to |
2147 | an address? | |
93b45514 | 2148 | @item |
47342e8f | 2149 | How long (in bytes) is this reference? |
93b45514 | 2150 | @item |
24b1493d | 2151 | Which section does the address refer to? What is the numeric value of |
b50e59fe | 2152 | @display |
24b1493d | 2153 | (@var{address}) @minus{} (@var{start-address of section})? |
b50e59fe | 2154 | @end display |
93b45514 | 2155 | @item |
b50e59fe | 2156 | Is the reference to an address ``Program-Counter relative''? |
93b45514 RP |
2157 | @end itemize |
2158 | ||
66b818fb RP |
2159 | @cindex addresses, format of |
2160 | @cindex section-relative addressing | |
f009d0ab | 2161 | In fact, every address @code{@value{AS}} ever uses is expressed as |
d0281557 | 2162 | @display |
24b1493d | 2163 | (@var{section}) + (@var{offset into section}) |
d0281557 RP |
2164 | @end display |
2165 | @noindent | |
65fbb2d7 RP |
2166 | Further, most expressions @code{@value{AS}} computes have this section-relative |
2167 | nature. | |
2168 | @ifset SOM | |
2169 | (For some object formats, such as SOM for the HPPA, some expressions are | |
2170 | symbol-relative instead.) | |
2171 | @end ifset | |
dd565f85 RP |
2172 | |
2173 | In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset | |
2174 | @var{N} into section @var{secname}.'' | |
24b1493d RP |
2175 | |
2176 | Apart from text, data and bss sections you need to know about the | |
f009d0ab | 2177 | @dfn{absolute} section. When @code{@value{LD}} mixes partial programs, |
66b818fb | 2178 | addresses in the absolute section remain unchanged. For example, address |
05a0e43b RP |
2179 | @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by |
2180 | @code{@value{LD}}. Although the linker never arranges two partial programs' | |
2181 | data sections with overlapping addresses after linking, @emph{by definition} | |
2182 | their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one | |
2183 | part of a program is always the same address when the program is running as | |
2184 | address @code{@{absolute@ 239@}} in any other part of the program. | |
47342e8f | 2185 | |
24b1493d RP |
2186 | The idea of sections is extended to the @dfn{undefined} section. Any |
2187 | address whose section is unknown at assembly time is by definition | |
05a0e43b | 2188 | rendered @{undefined @var{U}@}---where @var{U} is filled in later. |
47342e8f | 2189 | Since numbers are always defined, the only way to generate an undefined |
93b45514 RP |
2190 | address is to mention an undefined symbol. A reference to a named |
2191 | common block would be such a symbol: its value is unknown at assembly | |
24b1493d | 2192 | time so it has section @emph{undefined}. |
93b45514 | 2193 | |
24b1493d | 2194 | By analogy the word @emph{section} is used to describe groups of sections in |
f009d0ab | 2195 | the linked program. @code{@value{LD}} puts all partial programs' text |
24b1493d RP |
2196 | sections in contiguous addresses in the linked program. It is |
2197 | customary to refer to the @emph{text section} of a program, meaning all | |
05a0e43b | 2198 | the addresses of all partial programs' text sections. Likewise for |
24b1493d | 2199 | data and bss sections. |
93b45514 | 2200 | |
f009d0ab RP |
2201 | Some sections are manipulated by @code{@value{LD}}; others are invented for |
2202 | use of @code{@value{AS}} and have no meaning except during assembly. | |
47342e8f | 2203 | |
f009d0ab | 2204 | @node Ld Sections |
3ffb03b1 | 2205 | @section Linker Sections |
f009d0ab | 2206 | @code{@value{LD}} deals with just four kinds of sections, summarized below. |
b50e59fe RP |
2207 | |
2208 | @table @strong | |
47342e8f | 2209 | |
f009d0ab | 2210 | @ifset COFF |
66b818fb RP |
2211 | @cindex named sections |
2212 | @cindex sections, named | |
24b1493d | 2213 | @item named sections |
f009d0ab RP |
2214 | @end ifset |
2215 | @ifset aout-bout | |
66b818fb RP |
2216 | @cindex text section |
2217 | @cindex data section | |
9dcf8057 | 2218 | @itemx text section |
24b1493d | 2219 | @itemx data section |
f009d0ab RP |
2220 | @end ifset |
2221 | These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as | |
24b1493d | 2222 | separate but equal sections. Anything you can say of one section is |
f009d0ab RP |
2223 | true another. |
2224 | @ifset aout-bout | |
24b1493d RP |
2225 | When the program is running, however, it is |
2226 | customary for the text section to be unalterable. The | |
05a0e43b | 2227 | text section is often shared among processes: it contains |
24b1493d | 2228 | instructions, constants and the like. The data section of a running |
b50e59fe | 2229 | program is usually alterable: for example, C variables would be stored |
24b1493d | 2230 | in the data section. |
f009d0ab | 2231 | @end ifset |
47342e8f | 2232 | |
66b818fb | 2233 | @cindex bss section |
24b1493d RP |
2234 | @item bss section |
2235 | This section contains zeroed bytes when your program begins running. It | |
47342e8f | 2236 | is used to hold unitialized variables or common storage. The length of |
24b1493d | 2237 | each partial program's bss section is important, but because it starts |
47342e8f | 2238 | out containing zeroed bytes there is no need to store explicit zero |
24b1493d | 2239 | bytes in the object file. The bss section was invented to eliminate |
d0281557 | 2240 | those explicit zeros from object files. |
47342e8f | 2241 | |
66b818fb | 2242 | @cindex absolute section |
24b1493d RP |
2243 | @item absolute section |
2244 | Address 0 of this section is always ``relocated'' to runtime address 0. | |
f009d0ab | 2245 | This is useful if you want to refer to an address that @code{@value{LD}} must |
47342e8f | 2246 | not change when relocating. In this sense we speak of absolute |
05a0e43b | 2247 | addresses being ``unrelocatable'': they do not change during relocation. |
47342e8f | 2248 | |
66b818fb | 2249 | @cindex undefined section |
24b1493d RP |
2250 | @item undefined section |
2251 | This ``section'' is a catch-all for address references to objects not in | |
2252 | the preceding sections. | |
47342e8f | 2253 | @c FIXME: ref to some other doc on obj-file formats could go here. |
93b45514 | 2254 | @end table |
47342e8f | 2255 | |
66b818fb | 2256 | @cindex relocation example |
f009d0ab RP |
2257 | An idealized example of three relocatable sections follows. |
2258 | @ifset COFF | |
66b818fb | 2259 | The example uses the traditional section names @samp{.text} and @samp{.data}. |
f009d0ab | 2260 | @end ifset |
24b1493d | 2261 | Memory addresses are on the horizontal axis. |
93b45514 | 2262 | |
7d7ecbdd | 2263 | @c TEXI2ROFF-KILL |
b50e59fe | 2264 | @ifinfo |
7d7ecbdd | 2265 | @c END TEXI2ROFF-KILL |
d0281557 | 2266 | @smallexample |
93b45514 RP |
2267 | +-----+----+--+ |
2268 | partial program # 1: |ttttt|dddd|00| | |
2269 | +-----+----+--+ | |
2270 | ||
2271 | text data bss | |
2272 | seg. seg. seg. | |
2273 | ||
2274 | +---+---+---+ | |
2275 | partial program # 2: |TTT|DDD|000| | |
2276 | +---+---+---+ | |
2277 | ||
2278 | +--+---+-----+--+----+---+-----+~~ | |
2279 | linked program: | |TTT|ttttt| |dddd|DDD|00000| | |
2280 | +--+---+-----+--+----+---+-----+~~ | |
2281 | ||
2282 | addresses: 0 @dots{} | |
d0281557 | 2283 | @end smallexample |
7d7ecbdd | 2284 | @c TEXI2ROFF-KILL |
b50e59fe | 2285 | @end ifinfo |
8babef85 | 2286 | @need 5000 |
b50e59fe | 2287 | @tex |
d0281557 | 2288 | |
66b818fb | 2289 | \line{\it Partial program \#1: \hfil} |
d0281557 RP |
2290 | \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
2291 | \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} | |
2292 | ||
66b818fb | 2293 | \line{\it Partial program \#2: \hfil} |
d0281557 RP |
2294 | \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
2295 | \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} | |
2296 | ||
66b818fb | 2297 | \line{\it linked program: \hfil} |
d0281557 RP |
2298 | \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} |
2299 | \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt | |
b50e59fe | 2300 | ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt |
d0281557 RP |
2301 | DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} |
2302 | ||
66b818fb | 2303 | \line{\it addresses: \hfil} |
d0281557 RP |
2304 | \line{0\dots\hfil} |
2305 | ||
b50e59fe | 2306 | @end tex |
7d7ecbdd | 2307 | @c END TEXI2ROFF-KILL |
93b45514 | 2308 | |
f009d0ab | 2309 | @node As Sections |
3ffb03b1 | 2310 | @section Assembler Internal Sections |
66b818fb | 2311 | |
3ffb03b1 | 2312 | @cindex internal assembler sections |
66b818fb | 2313 | @cindex sections in messages, internal |
f009d0ab | 2314 | These sections are meant only for the internal use of @code{@value{AS}}. They |
05a0e43b | 2315 | have no meaning at run-time. You do not really need to know about these |
f009d0ab | 2316 | sections for most purposes; but they can be mentioned in @code{@value{AS}} |
24b1493d | 2317 | warning messages, so it might be helpful to have an idea of their |
f009d0ab | 2318 | meanings to @code{@value{AS}}. These sections are used to permit the |
24b1493d RP |
2319 | value of every expression in your assembly language program to be a |
2320 | section-relative address. | |
93b45514 | 2321 | |
d0281557 | 2322 | @table @b |
66b818fb | 2323 | @cindex assembler internal logic error |
71dd3c40 | 2324 | @item ASSEMBLER-INTERNAL-LOGIC-ERROR! |
24b1493d RP |
2325 | An internal assembler logic error has been found. This means there is a |
2326 | bug in the assembler. | |
2327 | ||
9dcf8057 | 2328 | @cindex expr (internal section) |
71dd3c40 | 2329 | @item expr section |
9dcf8057 JL |
2330 | The assembler stores complex expression internally as combinations of |
2331 | symbols. When it needs to represent an expression as a symbol, it puts | |
2332 | it in the expr section. | |
24b1493d RP |
2333 | @c FIXME item debug |
2334 | @c FIXME item transfer[t] vector preload | |
2335 | @c FIXME item transfer[t] vector postload | |
2336 | @c FIXME item register | |
93b45514 RP |
2337 | @end table |
2338 | ||
242d9c06 | 2339 | @node Sub-Sections |
24b1493d | 2340 | @section Sub-Sections |
66b818fb RP |
2341 | |
2342 | @cindex numbered subsections | |
2343 | @cindex grouping data | |
f009d0ab | 2344 | @ifset aout-bout |
24b1493d | 2345 | Assembled bytes |
f009d0ab | 2346 | @ifset COFF |
24b1493d | 2347 | conventionally |
f009d0ab RP |
2348 | @end ifset |
2349 | fall into two sections: text and data. | |
2350 | @end ifset | |
66b818fb | 2351 | You may have separate groups of |
f009d0ab | 2352 | @ifset GENERIC |
66b818fb | 2353 | data in named sections |
f009d0ab RP |
2354 | @end ifset |
2355 | @ifclear GENERIC | |
2356 | @ifclear aout-bout | |
2357 | data in named sections | |
2358 | @end ifclear | |
2359 | @ifset aout-bout | |
2360 | text or data | |
2361 | @end ifset | |
2362 | @end ifclear | |
05a0e43b RP |
2363 | that you want to end up near to each other in the object file, even though they |
2364 | are not contiguous in the assembler source. @code{@value{AS}} allows you to | |
2365 | use @dfn{subsections} for this purpose. Within each section, there can be | |
2366 | numbered subsections with values from 0 to 8192. Objects assembled into the | |
2367 | same subsection go into the object file together with other objects in the same | |
2368 | subsection. For example, a compiler might want to store constants in the text | |
2369 | section, but might not want to have them interspersed with the program being | |
2370 | assembled. In this case, the compiler could issue a @samp{.text 0} before each | |
2371 | section of code being output, and a @samp{.text 1} before each group of | |
2372 | constants being output. | |
2373 | ||
2374 | Subsections are optional. If you do not use subsections, everything | |
2375 | goes in subsection number zero. | |
93b45514 | 2376 | |
f009d0ab | 2377 | @ifset GENERIC |
24b1493d RP |
2378 | Each subsection is zero-padded up to a multiple of four bytes. |
2379 | (Subsections may be padded a different amount on different flavors | |
f009d0ab RP |
2380 | of @code{@value{AS}}.) |
2381 | @end ifset | |
2382 | @ifclear GENERIC | |
2383 | @ifset H8 | |
2384 | On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word | |
66b818fb | 2385 | boundary (two bytes). |
f009d0ab | 2386 | The same is true on the Hitachi SH. |
f009d0ab RP |
2387 | @end ifset |
2388 | @ifset I960 | |
24b1493d | 2389 | @c FIXME section padding (alignment)? |
d0281557 RP |
2390 | @c Rich Pixley says padding here depends on target obj code format; that |
2391 | @c doesn't seem particularly useful to say without further elaboration, | |
2392 | @c so for now I say nothing about it. If this is a generic BFD issue, | |
2393 | @c these paragraphs might need to vanish from this manual, and be | |
2394 | @c discussed in BFD chapter of binutils (or some such). | |
f009d0ab RP |
2395 | @end ifset |
2396 | @ifset A29K | |
66b818fb | 2397 | On the AMD 29K family, no particular padding is added to section or |
f009d0ab RP |
2398 | subsection sizes; @value{AS} forces no alignment on this platform. |
2399 | @end ifset | |
2400 | @end ifclear | |
66b818fb | 2401 | |
24b1493d | 2402 | Subsections appear in your object file in numeric order, lowest numbered |
b50e59fe | 2403 | to highest. (All this to be compatible with other people's assemblers.) |
f009d0ab | 2404 | The object file contains no representation of subsections; @code{@value{LD}} and |
05a0e43b | 2405 | other programs that manipulate object files see no trace of them. |
24b1493d RP |
2406 | They just see all your text subsections as a text section, and all your |
2407 | data subsections as a data section. | |
93b45514 | 2408 | |
24b1493d | 2409 | To specify which subsection you want subsequent statements assembled |
66b818fb RP |
2410 | into, use a numeric argument to specify it, in a @samp{.text |
2411 | @var{expression}} or a @samp{.data @var{expression}} statement. | |
f009d0ab RP |
2412 | @ifset COFF |
2413 | @ifset GENERIC | |
2414 | When generating COFF output, you | |
2415 | @end ifset | |
2416 | @ifclear GENERIC | |
66b818fb | 2417 | You |
f009d0ab | 2418 | @end ifclear |
66b818fb RP |
2419 | can also use an extra subsection |
2420 | argument with arbitrary named sections: @samp{.section @var{name}, | |
2421 | @var{expression}}. | |
f009d0ab | 2422 | @end ifset |
66b818fb RP |
2423 | @var{Expression} should be an absolute expression. |
2424 | (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0} | |
2425 | is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly | |
2426 | begins in @code{text 0}. For instance: | |
d0281557 | 2427 | @smallexample |
24b1493d RP |
2428 | .text 0 # The default subsection is text 0 anyway. |
2429 | .ascii "This lives in the first text subsection. *" | |
93b45514 | 2430 | .text 1 |
24b1493d | 2431 | .ascii "But this lives in the second text subsection." |
93b45514 | 2432 | .data 0 |
24b1493d RP |
2433 | .ascii "This lives in the data section," |
2434 | .ascii "in the first data subsection." | |
93b45514 | 2435 | .text 0 |
24b1493d | 2436 | .ascii "This lives in the first text section," |
93b45514 | 2437 | .ascii "immediately following the asterisk (*)." |
d0281557 | 2438 | @end smallexample |
93b45514 | 2439 | |
05a0e43b RP |
2440 | Each section has a @dfn{location counter} incremented by one for every byte |
2441 | assembled into that section. Because subsections are merely a convenience | |
2442 | restricted to @code{@value{AS}} there is no concept of a subsection location | |
2443 | counter. There is no way to directly manipulate a location counter---but the | |
2444 | @code{.align} directive changes it, and any label definition captures its | |
2445 | current value. The location counter of the section where statements are being | |
2446 | assembled is said to be the @dfn{active} location counter. | |
93b45514 | 2447 | |
242d9c06 | 2448 | @node bss |
24b1493d | 2449 | @section bss Section |
66b818fb RP |
2450 | |
2451 | @cindex bss section | |
2452 | @cindex common variable storage | |
24b1493d RP |
2453 | The bss section is used for local common variable storage. |
2454 | You may allocate address space in the bss section, but you may | |
93b45514 | 2455 | not dictate data to load into it before your program executes. When |
b50e59fe | 2456 | your program starts running, all the contents of the bss |
24b1493d | 2457 | section are zeroed bytes. |
93b45514 | 2458 | |
35cfacf0 ILT |
2459 | The @code{.lcomm} pseudo-op defines a symbol in the bss section; see |
2460 | @ref{Lcomm,,@code{.lcomm}}. | |
2461 | ||
2462 | The @code{.comm} pseudo-op may be used to declare a common symbol, which is | |
2463 | another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}. | |
2464 | ||
2465 | @ifset GENERIC | |
2466 | When assembling for a target which supports multiple sections, such as ELF or | |
2467 | COFF, you may switch into the @code{.bss} section and define symbols as usual; | |
2468 | see @ref{Section,,@code{.section}}. You may only assemble zero values into the | |
2469 | section. Typically the section will only contain symbol definitions and | |
2470 | @code{.skip} directives (@pxref{Skip,,@code{.skip}}). | |
2471 | @end ifset | |
93b45514 | 2472 | |
242d9c06 | 2473 | @node Symbols |
93b45514 | 2474 | @chapter Symbols |
66b818fb RP |
2475 | |
2476 | @cindex symbols | |
47342e8f RP |
2477 | Symbols are a central concept: the programmer uses symbols to name |
2478 | things, the linker uses symbols to link, and the debugger uses symbols | |
d0281557 | 2479 | to debug. |
47342e8f | 2480 | |
b50e59fe | 2481 | @quotation |
66b818fb | 2482 | @cindex debuggers, and symbol order |
f009d0ab | 2483 | @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in |
b50e59fe RP |
2484 | the same order they were declared. This may break some debuggers. |
2485 | @end quotation | |
93b45514 | 2486 | |
7a4c8e5c | 2487 | @menu |
ba487f3a RP |
2488 | * Labels:: Labels |
2489 | * Setting Symbols:: Giving Symbols Other Values | |
2490 | * Symbol Names:: Symbol Names | |
2491 | * Dot:: The Special Dot Symbol | |
2492 | * Symbol Attributes:: Symbol Attributes | |
7a4c8e5c RP |
2493 | @end menu |
2494 | ||
242d9c06 | 2495 | @node Labels |
93b45514 | 2496 | @section Labels |
66b818fb RP |
2497 | |
2498 | @cindex labels | |
93b45514 | 2499 | A @dfn{label} is written as a symbol immediately followed by a colon |
b50e59fe | 2500 | @samp{:}. The symbol then represents the current value of the |
93b45514 RP |
2501 | active location counter, and is, for example, a suitable instruction |
2502 | operand. You are warned if you use the same symbol to represent two | |
2503 | different locations: the first definition overrides any other | |
2504 | definitions. | |
2505 | ||
9dcf8057 | 2506 | @ifset HPPA |
81fcb3ff RP |
2507 | On the HPPA, the usual form for a label need not be immediately followed by a |
2508 | colon, but instead must start in column zero. Only one label may be defined on | |
2509 | a single line. To work around this, the HPPA version of @code{@value{AS}} also | |
2510 | provides a special directive @code{.label} for defining labels more flexibly. | |
9dcf8057 JL |
2511 | @end ifset |
2512 | ||
242d9c06 | 2513 | @node Setting Symbols |
93b45514 | 2514 | @section Giving Symbols Other Values |
66b818fb RP |
2515 | |
2516 | @cindex assigning values to symbols | |
2517 | @cindex symbol values, assigning | |
b50e59fe RP |
2518 | A symbol can be given an arbitrary value by writing a symbol, followed |
2519 | by an equals sign @samp{=}, followed by an expression | |
93b45514 | 2520 | (@pxref{Expressions}). This is equivalent to using the @code{.set} |
7a4c8e5c | 2521 | directive. @xref{Set,,@code{.set}}. |
93b45514 | 2522 | |
242d9c06 | 2523 | @node Symbol Names |
93b45514 | 2524 | @section Symbol Names |
66b818fb RP |
2525 | |
2526 | @cindex symbol names | |
2527 | @cindex names, symbol | |
f009d0ab RP |
2528 | @ifclear SPECIAL-SYMS |
2529 | Symbol names begin with a letter or with one of @samp{._}. On most | |
2530 | machines, you can also use @code{$} in symbol names; exceptions are | |
2531 | noted in @ref{Machine Dependencies}. That character may be followed by any | |
2532 | string of digits, letters, dollar signs (unless otherwise noted in | |
2533 | @ref{Machine Dependencies}), and underscores. | |
2534 | @end ifclear | |
2535 | @ifset A29K | |
b50e59fe RP |
2536 | For the AMD 29K family, @samp{?} is also allowed in the |
2537 | body of a symbol name, though not at its beginning. | |
f009d0ab RP |
2538 | @end ifset |
2539 | ||
2540 | @ifset SPECIAL-SYMS | |
2541 | @ifset H8 | |
2542 | Symbol names begin with a letter or with one of @samp{._}. On the | |
f009d0ab | 2543 | Hitachi SH or the |
f009d0ab RP |
2544 | H8/500, you can also use @code{$} in symbol names. That character may |
2545 | be followed by any string of digits, letters, dollar signs (save on the | |
2546 | H8/300), and underscores. | |
2547 | @end ifset | |
2548 | @end ifset | |
2549 | ||
2550 | Case of letters is significant: @code{foo} is a different symbol name | |
2551 | than @code{Foo}. | |
b50e59fe | 2552 | |
05a0e43b RP |
2553 | Each symbol has exactly one name. Each name in an assembly language program |
2554 | refers to exactly one symbol. You may use that symbol name any number of times | |
2555 | in a program. | |
93b45514 | 2556 | |
7a4c8e5c | 2557 | @subheading Local Symbol Names |
93b45514 | 2558 | |
66b818fb RP |
2559 | @cindex local symbol names |
2560 | @cindex symbol names, local | |
2561 | @cindex temporary symbol names | |
2562 | @cindex symbol names, temporary | |
93b45514 | 2563 | Local symbols help compilers and programmers use names temporarily. |
b50e59fe RP |
2564 | There are ten local symbol names, which are re-used throughout the |
2565 | program. You may refer to them using the names @samp{0} @samp{1} | |
2566 | @dots{} @samp{9}. To define a local symbol, write a label of the form | |
2567 | @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most | |
2568 | recent previous definition of that symbol write @samp{@b{N}b}, using the | |
2569 | same digit as when you defined the label. To refer to the next | |
2570 | definition of a local label, write @samp{@b{N}f}---where @b{N} gives you | |
2571 | a choice of 10 forward references. The @samp{b} stands for | |
2572 | ``backwards'' and the @samp{f} stands for ``forwards''. | |
2573 | ||
8babef85 | 2574 | Local symbols are not emitted by the current @sc{gnu} C compiler. |
93b45514 RP |
2575 | |
2576 | There is no restriction on how you can use these labels, but | |
2577 | remember that at any point in the assembly you can refer to at most | |
2578 | 10 prior local labels and to at most 10 forward local labels. | |
2579 | ||
47342e8f | 2580 | Local symbol names are only a notation device. They are immediately |
93b45514 | 2581 | transformed into more conventional symbol names before the assembler |
47342e8f RP |
2582 | uses them. The symbol names stored in the symbol table, appearing in |
2583 | error messages and optionally emitted to the object file have these | |
2584 | parts: | |
2585 | ||
2586 | @table @code | |
93b45514 | 2587 | @item L |
f009d0ab RP |
2588 | All local labels begin with @samp{L}. Normally both @code{@value{AS}} and |
2589 | @code{@value{LD}} forget symbols that start with @samp{L}. These labels are | |
05a0e43b RP |
2590 | used for symbols you are never intended to see. If you use the |
2591 | @samp{-L} option then @code{@value{AS}} retains these symbols in the | |
f009d0ab | 2592 | object file. If you also instruct @code{@value{LD}} to retain these symbols, |
93b45514 | 2593 | you may use them in debugging. |
47342e8f RP |
2594 | |
2595 | @item @var{digit} | |
93b45514 RP |
2596 | If the label is written @samp{0:} then the digit is @samp{0}. |
2597 | If the label is written @samp{1:} then the digit is @samp{1}. | |
2598 | And so on up through @samp{9:}. | |
47342e8f | 2599 | |
35cfacf0 | 2600 | @item @kbd{C-A} |
05a0e43b | 2601 | This unusual character is included so you do not accidentally invent |
93b45514 RP |
2602 | a symbol of the same name. The character has ASCII value |
2603 | @samp{\001}. | |
47342e8f RP |
2604 | |
2605 | @item @emph{ordinal number} | |
2606 | This is a serial number to keep the labels distinct. The first | |
93b45514 | 2607 | @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the |
47342e8f | 2608 | number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:} |
93b45514 RP |
2609 | through @samp{9:}. |
2610 | @end table | |
47342e8f | 2611 | |
35cfacf0 ILT |
2612 | For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th |
2613 | @code{3:} is named @code{L3@kbd{C-A}44}. | |
93b45514 | 2614 | |
242d9c06 | 2615 | @node Dot |
93b45514 RP |
2616 | @section The Special Dot Symbol |
2617 | ||
66b818fb RP |
2618 | @cindex dot (symbol) |
2619 | @cindex @code{.} (symbol) | |
2620 | @cindex current address | |
2621 | @cindex location counter | |
b50e59fe | 2622 | The special symbol @samp{.} refers to the current address that |
f009d0ab | 2623 | @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin: |
05a0e43b | 2624 | .long .} defines @code{melvin} to contain its own address. |
93b45514 RP |
2625 | Assigning a value to @code{.} is treated the same as a @code{.org} |
2626 | directive. Thus, the expression @samp{.=.+4} is the same as saying | |
f009d0ab | 2627 | @ifclear no-space-dir |
09352a5d | 2628 | @samp{.space 4}. |
f009d0ab RP |
2629 | @end ifclear |
2630 | @ifset no-space-dir | |
2631 | @ifset A29K | |
b50e59fe | 2632 | @samp{.block 4}. |
f009d0ab RP |
2633 | @end ifset |
2634 | @end ifset | |
b50e59fe | 2635 | |
242d9c06 | 2636 | @node Symbol Attributes |
93b45514 | 2637 | @section Symbol Attributes |
66b818fb RP |
2638 | |
2639 | @cindex symbol attributes | |
2640 | @cindex attributes, symbol | |
d0281557 | 2641 | Every symbol has, as well as its name, the attributes ``Value'' and |
66b818fb | 2642 | ``Type''. Depending on output format, symbols can also have auxiliary |
f009d0ab RP |
2643 | attributes. |
2644 | @ifset INTERNALS | |
2645 | The detailed definitions are in @file{a.out.h}. | |
2646 | @end ifset | |
93b45514 | 2647 | |
f009d0ab | 2648 | If you use a symbol without defining it, @code{@value{AS}} assumes zero for |
93b45514 RP |
2649 | all these attributes, and probably won't warn you. This makes the |
2650 | symbol an externally defined symbol, which is generally what you | |
2651 | would want. | |
2652 | ||
7a4c8e5c | 2653 | @menu |
ba487f3a RP |
2654 | * Symbol Value:: Value |
2655 | * Symbol Type:: Type | |
f009d0ab RP |
2656 | @ifset aout-bout |
2657 | @ifset GENERIC | |
2658 | * a.out Symbols:: Symbol Attributes: @code{a.out} | |
2659 | @end ifset | |
2660 | @ifclear GENERIC | |
2661 | @ifclear BOUT | |
ba487f3a | 2662 | * a.out Symbols:: Symbol Attributes: @code{a.out} |
f009d0ab RP |
2663 | @end ifclear |
2664 | @ifset BOUT | |
ba487f3a | 2665 | * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} |
f009d0ab RP |
2666 | @end ifset |
2667 | @end ifclear | |
2668 | @end ifset | |
2669 | @ifset COFF | |
ba487f3a | 2670 | * COFF Symbols:: Symbol Attributes for COFF |
f009d0ab | 2671 | @end ifset |
9dcf8057 JL |
2672 | @ifset SOM |
2673 | * SOM Symbols:: Symbol Attributes for SOM | |
2674 | @end ifset | |
7a4c8e5c RP |
2675 | @end menu |
2676 | ||
242d9c06 | 2677 | @node Symbol Value |
93b45514 | 2678 | @subsection Value |
66b818fb RP |
2679 | |
2680 | @cindex value of a symbol | |
2681 | @cindex symbol value | |
24b1493d RP |
2682 | The value of a symbol is (usually) 32 bits. For a symbol which labels a |
2683 | location in the text, data, bss or absolute sections the value is the | |
2684 | number of addresses from the start of that section to the label. | |
2685 | Naturally for text, data and bss sections the value of a symbol changes | |
f009d0ab | 2686 | as @code{@value{LD}} changes section base addresses during linking. Absolute |
24b1493d RP |
2687 | symbols' values do not change during linking: that is why they are |
2688 | called absolute. | |
93b45514 | 2689 | |
b50e59fe | 2690 | The value of an undefined symbol is treated in a special way. If it is |
05a0e43b RP |
2691 | 0 then the symbol is not defined in this assembler source file, and |
2692 | @code{@value{LD}} tries to determine its value from other files linked into the | |
2693 | same program. You make this kind of symbol simply by mentioning a symbol | |
b50e59fe RP |
2694 | name without defining it. A non-zero value represents a @code{.comm} |
2695 | common declaration. The value is how much common storage to reserve, in | |
2696 | bytes (addresses). The symbol refers to the first address of the | |
2697 | allocated storage. | |
93b45514 | 2698 | |
242d9c06 | 2699 | @node Symbol Type |
93b45514 | 2700 | @subsection Type |
66b818fb RP |
2701 | |
2702 | @cindex type of a symbol | |
2703 | @cindex symbol type | |
24b1493d | 2704 | The type attribute of a symbol contains relocation (section) |
d0281557 RP |
2705 | information, any flag settings indicating that a symbol is external, and |
2706 | (optionally), other information for linkers and debuggers. The exact | |
2707 | format depends on the object-code output format in use. | |
93b45514 | 2708 | |
f009d0ab RP |
2709 | @ifset aout-bout |
2710 | @ifclear GENERIC | |
2711 | @ifset BOUT | |
2712 | @c The following avoids a "widow" subsection title. @group would be | |
2713 | @c better if it were available outside examples. | |
2714 | @need 1000 | |
242d9c06 | 2715 | @node a.out Symbols |
d0281557 | 2716 | @subsection Symbol Attributes: @code{a.out}, @code{b.out} |
66b818fb RP |
2717 | |
2718 | @cindex @code{b.out} symbol attributes | |
2719 | @cindex symbol attributes, @code{b.out} | |
f009d0ab RP |
2720 | These symbol attributes appear only when @code{@value{AS}} is configured for |
2721 | one of the Berkeley-descended object output formats---@code{a.out} or | |
2722 | @code{b.out}. | |
2723 | ||
2724 | @end ifset | |
2725 | @ifclear BOUT | |
2726 | @node a.out Symbols | |
2727 | @subsection Symbol Attributes: @code{a.out} | |
2728 | ||
2729 | @cindex @code{a.out} symbol attributes | |
2730 | @cindex symbol attributes, @code{a.out} | |
2731 | ||
2732 | @end ifclear | |
2733 | @end ifclear | |
2734 | @ifset GENERIC | |
2735 | @node a.out Symbols | |
0b5b143a | 2736 | @subsection Symbol Attributes: @code{a.out} |
7a4c8e5c | 2737 | |
66b818fb RP |
2738 | @cindex @code{a.out} symbol attributes |
2739 | @cindex symbol attributes, @code{a.out} | |
2740 | ||
f009d0ab | 2741 | @end ifset |
7a4c8e5c | 2742 | @menu |
ba487f3a RP |
2743 | * Symbol Desc:: Descriptor |
2744 | * Symbol Other:: Other | |
7a4c8e5c | 2745 | @end menu |
93b45514 | 2746 | |
242d9c06 | 2747 | @node Symbol Desc |
d0281557 | 2748 | @subsubsection Descriptor |
66b818fb RP |
2749 | |
2750 | @cindex descriptor, of @code{a.out} symbol | |
93b45514 | 2751 | This is an arbitrary 16-bit value. You may establish a symbol's |
7a4c8e5c RP |
2752 | descriptor value by using a @code{.desc} statement |
2753 | (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to | |
f009d0ab | 2754 | @code{@value{AS}}. |
93b45514 | 2755 | |
242d9c06 | 2756 | @node Symbol Other |
d0281557 | 2757 | @subsubsection Other |
66b818fb RP |
2758 | |
2759 | @cindex other attribute, of @code{a.out} symbol | |
f009d0ab RP |
2760 | This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}. |
2761 | @end ifset | |
d0281557 | 2762 | |
f009d0ab | 2763 | @ifset COFF |
242d9c06 | 2764 | @node COFF Symbols |
d0281557 | 2765 | @subsection Symbol Attributes for COFF |
66b818fb RP |
2766 | |
2767 | @cindex COFF symbol attributes | |
2768 | @cindex symbol attributes, COFF | |
2769 | ||
d0281557 RP |
2770 | The COFF format supports a multitude of auxiliary symbol attributes; |
2771 | like the primary symbol attributes, they are set between @code{.def} and | |
f009d0ab | 2772 | @code{.endef} directives. |
d0281557 RP |
2773 | |
2774 | @subsubsection Primary Attributes | |
66b818fb RP |
2775 | |
2776 | @cindex primary attributes, COFF symbols | |
d0281557 RP |
2777 | The symbol name is set with @code{.def}; the value and type, |
2778 | respectively, with @code{.val} and @code{.type}. | |
2779 | ||
2780 | @subsubsection Auxiliary Attributes | |
66b818fb RP |
2781 | |
2782 | @cindex auxiliary attributes, COFF symbols | |
f009d0ab | 2783 | The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, |
d0281557 RP |
2784 | @code{.size}, and @code{.tag} can generate auxiliary symbol table |
2785 | information for COFF. | |
f009d0ab | 2786 | @end ifset |
93b45514 | 2787 | |
9dcf8057 JL |
2788 | @ifset SOM |
2789 | @node SOM Symbols | |
2790 | @subsection Symbol Attributes for SOM | |
2791 | ||
2792 | @cindex SOM symbol attributes | |
2793 | @cindex symbol attributes, SOM | |
2794 | ||
05a0e43b RP |
2795 | The SOM format for the HPPA supports a multitude of symbol attributes set with |
2796 | the @code{.EXPORT} and @code{.IMPORT} directives. | |
9dcf8057 JL |
2797 | |
2798 | The attributes are described in @cite{HP9000 Series 800 Assembly | |
2799 | Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and | |
2800 | @code{EXPORT} assembler directive documentation. | |
2801 | @end ifset | |
2802 | ||
242d9c06 | 2803 | @node Expressions |
93b45514 | 2804 | @chapter Expressions |
66b818fb RP |
2805 | |
2806 | @cindex expressions | |
2807 | @cindex addresses | |
2808 | @cindex numeric values | |
93b45514 RP |
2809 | An @dfn{expression} specifies an address or numeric value. |
2810 | Whitespace may precede and/or follow an expression. | |
2811 | ||
dd565f85 RP |
2812 | The result of an expression must be an absolute number, or else an offset into |
2813 | a particular section. If an expression is not absolute, and there is not | |
2814 | enough information when @code{@value{AS}} sees the expression to know its | |
2815 | section, a second pass over the source program might be necessary to interpret | |
2816 | the expression---but the second pass is currently not implemented. | |
2817 | @code{@value{AS}} aborts with an error message in this situation. | |
2818 | ||
7a4c8e5c | 2819 | @menu |
ba487f3a RP |
2820 | * Empty Exprs:: Empty Expressions |
2821 | * Integer Exprs:: Integer Expressions | |
7a4c8e5c RP |
2822 | @end menu |
2823 | ||
242d9c06 | 2824 | @node Empty Exprs |
93b45514 | 2825 | @section Empty Expressions |
66b818fb RP |
2826 | |
2827 | @cindex empty expressions | |
2828 | @cindex expressions, empty | |
47342e8f | 2829 | An empty expression has no value: it is just whitespace or null. |
93b45514 | 2830 | Wherever an absolute expression is required, you may omit the |
05a0e43b | 2831 | expression, and @code{@value{AS}} assumes a value of (absolute) 0. This |
93b45514 RP |
2832 | is compatible with other assemblers. |
2833 | ||
242d9c06 | 2834 | @node Integer Exprs |
93b45514 | 2835 | @section Integer Expressions |
66b818fb RP |
2836 | |
2837 | @cindex integer expressions | |
2838 | @cindex expressions, integer | |
47342e8f RP |
2839 | An @dfn{integer expression} is one or more @emph{arguments} delimited |
2840 | by @emph{operators}. | |
2841 | ||
7a4c8e5c | 2842 | @menu |
ba487f3a RP |
2843 | * Arguments:: Arguments |
2844 | * Operators:: Operators | |
2845 | * Prefix Ops:: Prefix Operators | |
2846 | * Infix Ops:: Infix Operators | |
7a4c8e5c RP |
2847 | @end menu |
2848 | ||
242d9c06 | 2849 | @node Arguments |
47342e8f | 2850 | @subsection Arguments |
93b45514 | 2851 | |
66b818fb RP |
2852 | @cindex expression arguments |
2853 | @cindex arguments in expressions | |
2854 | @cindex operands in expressions | |
2855 | @cindex arithmetic operands | |
47342e8f RP |
2856 | @dfn{Arguments} are symbols, numbers or subexpressions. In other |
2857 | contexts arguments are sometimes called ``arithmetic operands''. In | |
2858 | this manual, to avoid confusing them with the ``instruction operands'' of | |
2859 | the machine language, we use the term ``argument'' to refer to parts of | |
b50e59fe | 2860 | expressions only, reserving the word ``operand'' to refer only to machine |
d0281557 | 2861 | instruction operands. |
93b45514 | 2862 | |
24b1493d RP |
2863 | Symbols are evaluated to yield @{@var{section} @var{NNN}@} where |
2864 | @var{section} is one of text, data, bss, absolute, | |
d0281557 | 2865 | or undefined. @var{NNN} is a signed, 2's complement 32 bit |
93b45514 RP |
2866 | integer. |
2867 | ||
2868 | Numbers are usually integers. | |
2869 | ||
2870 | A number can be a flonum or bignum. In this case, you are warned | |
f009d0ab | 2871 | that only the low order 32 bits are used, and @code{@value{AS}} pretends |
93b45514 RP |
2872 | these 32 bits are an integer. You may write integer-manipulating |
2873 | instructions that act on exotic constants, compatible with other | |
2874 | assemblers. | |
2875 | ||
66b818fb | 2876 | @cindex subexpressions |
b50e59fe RP |
2877 | Subexpressions are a left parenthesis @samp{(} followed by an integer |
2878 | expression, followed by a right parenthesis @samp{)}; or a prefix | |
47342e8f | 2879 | operator followed by an argument. |
93b45514 | 2880 | |
242d9c06 | 2881 | @node Operators |
93b45514 | 2882 | @subsection Operators |
66b818fb RP |
2883 | |
2884 | @cindex operators, in expressions | |
2885 | @cindex arithmetic functions | |
2886 | @cindex functions, in expressions | |
b50e59fe RP |
2887 | @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix |
2888 | operators are followed by an argument. Infix operators appear | |
47342e8f | 2889 | between their arguments. Operators may be preceded and/or followed by |
93b45514 RP |
2890 | whitespace. |
2891 | ||
242d9c06 | 2892 | @node Prefix Ops |
66b818fb RP |
2893 | @subsection Prefix Operator |
2894 | ||
2895 | @cindex prefix operators | |
f009d0ab | 2896 | @code{@value{AS}} has the following @dfn{prefix operators}. They each take |
47342e8f | 2897 | one argument, which must be absolute. |
d0281557 RP |
2898 | |
2899 | @c the tex/end tex stuff surrounding this small table is meant to make | |
2900 | @c it align, on the printed page, with the similar table in the next | |
2901 | @c section (which is inside an enumerate). | |
2902 | @tex | |
2903 | \global\advance\leftskip by \itemindent | |
2904 | @end tex | |
2905 | ||
b50e59fe | 2906 | @table @code |
93b45514 | 2907 | @item - |
b50e59fe | 2908 | @dfn{Negation}. Two's complement negation. |
93b45514 | 2909 | @item ~ |
b50e59fe | 2910 | @dfn{Complementation}. Bitwise not. |
93b45514 RP |
2911 | @end table |
2912 | ||
d0281557 RP |
2913 | @tex |
2914 | \global\advance\leftskip by -\itemindent | |
2915 | @end tex | |
2916 | ||
242d9c06 | 2917 | @node Infix Ops |
b50e59fe | 2918 | @subsection Infix Operators |
47342e8f | 2919 | |
66b818fb RP |
2920 | @cindex infix operators |
2921 | @cindex operators, permitted arguments | |
b50e59fe RP |
2922 | @dfn{Infix operators} take two arguments, one on either side. Operators |
2923 | have precedence, but operations with equal precedence are performed left | |
2924 | to right. Apart from @code{+} or @code{-}, both arguments must be | |
2925 | absolute, and the result is absolute. | |
47342e8f | 2926 | |
93b45514 | 2927 | @enumerate |
66b818fb RP |
2928 | @cindex operator precedence |
2929 | @cindex precedence of operators | |
47342e8f | 2930 | |
93b45514 | 2931 | @item |
47342e8f | 2932 | Highest Precedence |
66b818fb | 2933 | |
93b45514 RP |
2934 | @table @code |
2935 | @item * | |
2936 | @dfn{Multiplication}. | |
66b818fb | 2937 | |
93b45514 RP |
2938 | @item / |
2939 | @dfn{Division}. Truncation is the same as the C operator @samp{/} | |
66b818fb | 2940 | |
93b45514 RP |
2941 | @item % |
2942 | @dfn{Remainder}. | |
66b818fb | 2943 | |
f009d0ab RP |
2944 | @item < |
2945 | @itemx << | |
2946 | @dfn{Shift Left}. Same as the C operator @samp{<<}. | |
66b818fb | 2947 | |
f009d0ab RP |
2948 | @item > |
2949 | @itemx >> | |
2950 | @dfn{Shift Right}. Same as the C operator @samp{>>}. | |
93b45514 | 2951 | @end table |
47342e8f | 2952 | |
93b45514 | 2953 | @item |
47342e8f | 2954 | Intermediate precedence |
66b818fb | 2955 | |
47342e8f | 2956 | @table @code |
93b45514 | 2957 | @item | |
66b818fb | 2958 | |
93b45514 | 2959 | @dfn{Bitwise Inclusive Or}. |
66b818fb | 2960 | |
93b45514 RP |
2961 | @item & |
2962 | @dfn{Bitwise And}. | |
66b818fb | 2963 | |
93b45514 RP |
2964 | @item ^ |
2965 | @dfn{Bitwise Exclusive Or}. | |
66b818fb | 2966 | |
93b45514 RP |
2967 | @item ! |
2968 | @dfn{Bitwise Or Not}. | |
2969 | @end table | |
47342e8f | 2970 | |
93b45514 | 2971 | @item |
47342e8f | 2972 | Lowest Precedence |
66b818fb | 2973 | |
47342e8f | 2974 | @table @code |
66b818fb RP |
2975 | @cindex addition, permitted arguments |
2976 | @cindex plus, permitted arguments | |
2977 | @cindex arguments for addition | |
71dd3c40 | 2978 | @item + |
dd565f85 RP |
2979 | @dfn{Addition}. If either argument is absolute, the result has the section of |
2980 | the other argument. You may not add together arguments from different | |
2981 | sections. | |
66b818fb | 2982 | |
66b818fb RP |
2983 | @cindex subtraction, permitted arguments |
2984 | @cindex minus, permitted arguments | |
2985 | @cindex arguments for subtraction | |
71dd3c40 | 2986 | @item - |
47342e8f | 2987 | @dfn{Subtraction}. If the right argument is absolute, the |
24b1493d | 2988 | result has the section of the left argument. |
dd565f85 RP |
2989 | If both arguments are in the same section, the result is absolute. |
2990 | You may not subtract arguments from different sections. | |
2991 | @c FIXME is there still something useful to say about undefined - undefined ? | |
93b45514 RP |
2992 | @end table |
2993 | @end enumerate | |
2994 | ||
dd565f85 RP |
2995 | In short, it's only meaningful to add or subtract the @emph{offsets} in an |
2996 | address; you can only have a defined section in one of the two arguments. | |
47342e8f | 2997 | |
242d9c06 | 2998 | @node Pseudo Ops |
93b45514 | 2999 | @chapter Assembler Directives |
d0281557 | 3000 | |
66b818fb RP |
3001 | @cindex directives, machine independent |
3002 | @cindex pseudo-ops, machine independent | |
3003 | @cindex machine independent directives | |
d0281557 | 3004 | All assembler directives have names that begin with a period (@samp{.}). |
66b818fb | 3005 | The rest of the name is letters, usually in lower case. |
d0281557 | 3006 | |
f009d0ab | 3007 | This chapter discusses directives that are available regardless of the |
8babef85 | 3008 | target machine configuration for the @sc{gnu} assembler. |
f009d0ab RP |
3009 | @ifset GENERIC |
3010 | Some machine configurations provide additional directives. | |
3011 | @xref{Machine Dependencies}. | |
3012 | @end ifset | |
3013 | @ifclear GENERIC | |
3014 | @ifset machine-directives | |
3015 | @xref{Machine Dependencies} for additional directives. | |
3016 | @end ifset | |
3017 | @end ifclear | |
d0281557 | 3018 | |
7a4c8e5c | 3019 | @menu |
ba487f3a | 3020 | * Abort:: @code{.abort} |
f009d0ab RP |
3021 | @ifset COFF |
3022 | * ABORT:: @code{.ABORT} | |
3023 | @end ifset | |
3024 | ||
ba487f3a | 3025 | * Align:: @code{.align @var{abs-expr} , @var{abs-expr}} |
ba487f3a RP |
3026 | * Ascii:: @code{.ascii "@var{string}"}@dots{} |
3027 | * Asciz:: @code{.asciz "@var{string}"}@dots{} | |
931a8fab | 3028 | * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} |
ba487f3a RP |
3029 | * Byte:: @code{.byte @var{expressions}} |
3030 | * Comm:: @code{.comm @var{symbol} , @var{length} } | |
3031 | * Data:: @code{.data @var{subsection}} | |
f009d0ab | 3032 | @ifset COFF |
ba487f3a | 3033 | * Def:: @code{.def @var{name}} |
f009d0ab RP |
3034 | @end ifset |
3035 | @ifset aout-bout | |
ba487f3a | 3036 | * Desc:: @code{.desc @var{symbol}, @var{abs-expression}} |
f009d0ab RP |
3037 | @end ifset |
3038 | @ifset COFF | |
ba487f3a | 3039 | * Dim:: @code{.dim} |
f009d0ab RP |
3040 | @end ifset |
3041 | ||
ba487f3a RP |
3042 | * Double:: @code{.double @var{flonums}} |
3043 | * Eject:: @code{.eject} | |
3044 | * Else:: @code{.else} | |
1ca26844 | 3045 | * End:: @code{.end} |
f009d0ab | 3046 | @ifset COFF |
ba487f3a | 3047 | * Endef:: @code{.endef} |
f009d0ab RP |
3048 | @end ifset |
3049 | ||
71c2d792 | 3050 | * Endfunc:: @code{.endfunc} |
ba487f3a RP |
3051 | * Endif:: @code{.endif} |
3052 | * Equ:: @code{.equ @var{symbol}, @var{expression}} | |
35cfacf0 ILT |
3053 | * Equiv:: @code{.equiv @var{symbol}, @var{expression}} |
3054 | * Err:: @code{.err} | |
1ca26844 | 3055 | * Exitm:: @code{.exitm} |
ba487f3a | 3056 | * Extern:: @code{.extern} |
1ca26844 | 3057 | * Fail:: @code{.fail} |
f009d0ab | 3058 | @ifclear no-file-dir |
ba487f3a | 3059 | * File:: @code{.file @var{string}} |
f009d0ab RP |
3060 | @end ifclear |
3061 | ||
ba487f3a RP |
3062 | * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} |
3063 | * Float:: @code{.float @var{flonums}} | |
71c2d792 | 3064 | * Func:: @code{.func} |
ba487f3a RP |
3065 | * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} |
3066 | * hword:: @code{.hword @var{expressions}} | |
3067 | * Ident:: @code{.ident} | |
3068 | * If:: @code{.if @var{absolute expression}} | |
3069 | * Include:: @code{.include "@var{file}"} | |
3070 | * Int:: @code{.int @var{expressions}} | |
95074dc3 ILT |
3071 | * Irp:: @code{.irp @var{symbol},@var{values}}@dots{} |
3072 | * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} | |
ba487f3a | 3073 | * Lcomm:: @code{.lcomm @var{symbol} , @var{length}} |
66b818fb | 3074 | * Lflags:: @code{.lflags} |
f009d0ab | 3075 | @ifclear no-line-dir |
ba487f3a | 3076 | * Line:: @code{.line @var{line-number}} |
f009d0ab RP |
3077 | @end ifclear |
3078 | ||
ba487f3a | 3079 | * Ln:: @code{.ln @var{line-number}} |
910d7df2 | 3080 | * Linkonce:: @code{.linkonce [@var{type}]} |
ba487f3a RP |
3081 | * List:: @code{.list} |
3082 | * Long:: @code{.long @var{expressions}} | |
f009d0ab | 3083 | @ignore |
ba487f3a | 3084 | * Lsym:: @code{.lsym @var{symbol}, @var{expression}} |
f009d0ab RP |
3085 | @end ignore |
3086 | ||
95074dc3 | 3087 | * Macro:: @code{.macro @var{name} @var{args}}@dots{} |
910d7df2 | 3088 | * MRI:: @code{.mri @var{val}} |
95074dc3 | 3089 | |
ba487f3a RP |
3090 | * Nolist:: @code{.nolist} |
3091 | * Octa:: @code{.octa @var{bignums}} | |
3092 | * Org:: @code{.org @var{new-lc} , @var{fill}} | |
931a8fab | 3093 | * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}} |
1ca26844 | 3094 | * Print:: @code{.print @var{string}} |
66b818fb | 3095 | * Psize:: @code{.psize @var{lines}, @var{columns}} |
1ca26844 | 3096 | * Purgem:: @code{.purgem @var{name}} |
ba487f3a | 3097 | * Quad:: @code{.quad @var{bignums}} |
95074dc3 | 3098 | * Rept:: @code{.rept @var{count}} |
ba487f3a | 3099 | * Sbttl:: @code{.sbttl "@var{subheading}"} |
f009d0ab | 3100 | @ifset COFF |
ba487f3a | 3101 | * Scl:: @code{.scl @var{class}} |
66b818fb | 3102 | * Section:: @code{.section @var{name}, @var{subsection}} |
f009d0ab RP |
3103 | @end ifset |
3104 | ||
ba487f3a RP |
3105 | * Set:: @code{.set @var{symbol}, @var{expression}} |
3106 | * Short:: @code{.short @var{expressions}} | |
3107 | * Single:: @code{.single @var{flonums}} | |
f009d0ab | 3108 | @ifset COFF |
ba487f3a | 3109 | * Size:: @code{.size} |
f009d0ab RP |
3110 | @end ifset |
3111 | ||
910d7df2 | 3112 | * Skip:: @code{.skip @var{size} , @var{fill}} |
3ffb03b1 | 3113 | * Sleb128:: @code{.sleb128 @var{expressions}} |
ba487f3a | 3114 | * Space:: @code{.space @var{size} , @var{fill}} |
f009d0ab | 3115 | @ifset have-stabs |
ba487f3a | 3116 | * Stab:: @code{.stabd, .stabn, .stabs} |
f009d0ab | 3117 | @end ifset |
e680d737 RP |
3118 | |
3119 | * String:: @code{.string "@var{str}"} | |
1ca26844 | 3120 | * Struct:: @code{.struct @var{expression}} |
35cfacf0 ILT |
3121 | @ifset ELF |
3122 | * Symver:: @code{.symver @var{name},@var{name2@@nodename}} | |
3123 | @end ifset | |
f009d0ab | 3124 | @ifset COFF |
ba487f3a | 3125 | * Tag:: @code{.tag @var{structname}} |
f009d0ab RP |
3126 | @end ifset |
3127 | ||
ba487f3a RP |
3128 | * Text:: @code{.text @var{subsection}} |
3129 | * Title:: @code{.title "@var{heading}"} | |
f009d0ab | 3130 | @ifset COFF |
ba487f3a RP |
3131 | * Type:: @code{.type @var{int}} |
3132 | * Val:: @code{.val @var{addr}} | |
f009d0ab RP |
3133 | @end ifset |
3134 | ||
3ffb03b1 | 3135 | * Uleb128:: @code{.uleb128 @var{expressions}} |
ba487f3a RP |
3136 | * Word:: @code{.word @var{expressions}} |
3137 | * Deprecated:: Deprecated Directives | |
7a4c8e5c RP |
3138 | @end menu |
3139 | ||
242d9c06 | 3140 | @node Abort |
b50e59fe | 3141 | @section @code{.abort} |
66b818fb RP |
3142 | |
3143 | @cindex @code{abort} directive | |
3144 | @cindex stopping the assembly | |
93b45514 RP |
3145 | This directive stops the assembly immediately. It is for |
3146 | compatibility with other assemblers. The original idea was that the | |
d0281557 | 3147 | assembly language source would be piped into the assembler. If the sender |
f009d0ab | 3148 | of the source quit, it could use this directive tells @code{@value{AS}} to |
93b45514 RP |
3149 | quit also. One day @code{.abort} will not be supported. |
3150 | ||
f009d0ab RP |
3151 | @ifset COFF |
3152 | @node ABORT | |
d0281557 | 3153 | @section @code{.ABORT} |
66b818fb RP |
3154 | |
3155 | @cindex @code{ABORT} directive | |
f009d0ab | 3156 | When producing COFF output, @code{@value{AS}} accepts this directive as a |
d0281557 | 3157 | synonym for @samp{.abort}. |
66b818fb | 3158 | |
f009d0ab RP |
3159 | @ifset BOUT |
3160 | When producing @code{b.out} output, @code{@value{AS}} accepts this directive, | |
d0281557 | 3161 | but ignores it. |
f009d0ab RP |
3162 | @end ifset |
3163 | @end ifset | |
d0281557 | 3164 | |
242d9c06 | 3165 | @node Align |
c6c7035c | 3166 | @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
66b818fb RP |
3167 | |
3168 | @cindex padding the location counter | |
66b818fb | 3169 | @cindex @code{align} directive |
c6c7035c MM |
3170 | Pad the location counter (in the current subsection) to a particular storage |
3171 | boundary. The first expression (which must be absolute) is the alignment | |
3172 | required, as described below. | |
3173 | ||
3174 | The second expression (also absolute) gives the fill value to be stored in the | |
3175 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
3176 | padding bytes are normally zero. However, on some systems, if the section is | |
3177 | marked as containing code and the fill value is omitted, the space is filled | |
3178 | with no-op instructions. | |
3179 | ||
3180 | The third expression is also absolute, and is also optional. If it is present, | |
3181 | it is the maximum number of bytes that should be skipped by this alignment | |
3182 | directive. If doing the alignment would require skipping more bytes than the | |
3183 | specified maximum, then the alignment is not done at all. You can omit the | |
3184 | fill value (the second argument) entirely by simply using two commas after the | |
3185 | required alignment; this can be useful if you want the alignment to be filled | |
3186 | with no-op instructions when appropriate. | |
93b45514 | 3187 | |
931a8fab | 3188 | The way the required alignment is specified varies from system to system. |
910d7df2 | 3189 | For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF |
71dd3c40 | 3190 | format, |
931a8fab | 3191 | the first expression is the |
05a0e43b | 3192 | alignment request in bytes. For example @samp{.align 8} advances |
9dcf8057 JL |
3193 | the location counter until it is a multiple of 8. If the location counter |
3194 | is already a multiple of 8, no change is needed. | |
9dcf8057 | 3195 | |
931a8fab KR |
3196 | For other systems, including the i386 using a.out format, it is the |
3197 | number of low-order zero bits the location counter must have after | |
3198 | advancement. For example @samp{.align 3} advances the location | |
3199 | counter until it a multiple of 8. If the location counter is already a | |
3200 | multiple of 8, no change is needed. | |
3201 | ||
3202 | This inconsistency is due to the different behaviors of the various | |
3203 | native assemblers for these systems which GAS must emulate. | |
3204 | GAS also provides @code{.balign} and @code{.p2align} directives, | |
3205 | described later, which have a consistent behavior across all | |
3206 | architectures (but are specific to GAS). | |
93b45514 | 3207 | |
242d9c06 | 3208 | @node Ascii |
b50e59fe | 3209 | @section @code{.ascii "@var{string}"}@dots{} |
66b818fb RP |
3210 | |
3211 | @cindex @code{ascii} directive | |
3212 | @cindex string literals | |
47342e8f | 3213 | @code{.ascii} expects zero or more string literals (@pxref{Strings}) |
93b45514 RP |
3214 | separated by commas. It assembles each string (with no automatic |
3215 | trailing zero byte) into consecutive addresses. | |
3216 | ||
242d9c06 | 3217 | @node Asciz |
b50e59fe | 3218 | @section @code{.asciz "@var{string}"}@dots{} |
66b818fb RP |
3219 | |
3220 | @cindex @code{asciz} directive | |
3221 | @cindex zero-terminated strings | |
3222 | @cindex null-terminated strings | |
b50e59fe RP |
3223 | @code{.asciz} is just like @code{.ascii}, but each string is followed by |
3224 | a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. | |
93b45514 | 3225 | |
931a8fab | 3226 | @node Balign |
c6c7035c | 3227 | @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
931a8fab KR |
3228 | |
3229 | @cindex padding the location counter given number of bytes | |
3230 | @cindex @code{balign} directive | |
3231 | Pad the location counter (in the current subsection) to a particular | |
3232 | storage boundary. The first expression (which must be absolute) is the | |
3233 | alignment request in bytes. For example @samp{.balign 8} advances | |
3234 | the location counter until it is a multiple of 8. If the location counter | |
3235 | is already a multiple of 8, no change is needed. | |
3236 | ||
c6c7035c MM |
3237 | The second expression (also absolute) gives the fill value to be stored in the |
3238 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
3239 | padding bytes are normally zero. However, on some systems, if the section is | |
3240 | marked as containing code and the fill value is omitted, the space is filled | |
3241 | with no-op instructions. | |
3242 | ||
3243 | The third expression is also absolute, and is also optional. If it is present, | |
3244 | it is the maximum number of bytes that should be skipped by this alignment | |
3245 | directive. If doing the alignment would require skipping more bytes than the | |
3246 | specified maximum, then the alignment is not done at all. You can omit the | |
3247 | fill value (the second argument) entirely by simply using two commas after the | |
3248 | required alignment; this can be useful if you want the alignment to be filled | |
3249 | with no-op instructions when appropriate. | |
931a8fab | 3250 | |
71dd3c40 ILT |
3251 | @cindex @code{balignw} directive |
3252 | @cindex @code{balignl} directive | |
3253 | The @code{.balignw} and @code{.balignl} directives are variants of the | |
3254 | @code{.balign} directive. The @code{.balignw} directive treats the fill | |
3255 | pattern as a two byte word value. The @code{.balignl} directives treats the | |
3256 | fill pattern as a four byte longword value. For example, @code{.balignw | |
3257 | 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
3258 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
3259 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
3260 | undefined. | |
3261 | ||
242d9c06 | 3262 | @node Byte |
b50e59fe | 3263 | @section @code{.byte @var{expressions}} |
93b45514 | 3264 | |
66b818fb RP |
3265 | @cindex @code{byte} directive |
3266 | @cindex integers, one byte | |
47342e8f | 3267 | @code{.byte} expects zero or more expressions, separated by commas. |
93b45514 RP |
3268 | Each expression is assembled into the next byte. |
3269 | ||
242d9c06 | 3270 | @node Comm |
b50e59fe | 3271 | @section @code{.comm @var{symbol} , @var{length} } |
66b818fb RP |
3272 | |
3273 | @cindex @code{comm} directive | |
3274 | @cindex symbol, common | |
35cfacf0 ILT |
3275 | @code{.comm} declares a common symbol named @var{symbol}. When linking, a |
3276 | common symbol in one object file may be merged with a defined or common symbol | |
3277 | of the same name in another object file. If @code{@value{LD}} does not see a | |
3278 | definition for the symbol--just one or more common symbols--then it will | |
3279 | allocate @var{length} bytes of uninitialized memory. @var{length} must be an | |
3280 | absolute expression. If @code{@value{LD}} sees multiple common symbols with | |
3281 | the same name, and they do not all have the same size, it will allocate space | |
3282 | using the largest size. | |
3283 | ||
3284 | @ifset ELF | |
3285 | When using ELF, the @code{.comm} directive takes an optional third argument. | |
3286 | This is the desired alignment of the symbol, specified as a byte boundary (for | |
3287 | example, an alignment of 16 means that the least significant 4 bits of the | |
3288 | address should be zero). The alignment must be an absolute expression, and it | |
3289 | must be a power of two. If @code{@value{LD}} allocates uninitialized memory | |
3290 | for the common symbol, it will use the alignment when placing the symbol. If | |
3291 | no alignment is specified, @code{@value{AS}} will set the alignment to the | |
3292 | largest power of two less than or equal to the size of the symbol, up to a | |
3293 | maximum of 16. | |
3294 | @end ifset | |
47342e8f | 3295 | |
9dcf8057 JL |
3296 | @ifset HPPA |
3297 | The syntax for @code{.comm} differs slightly on the HPPA. The syntax is | |
509d5555 | 3298 | @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. |
9dcf8057 JL |
3299 | @end ifset |
3300 | ||
242d9c06 | 3301 | @node Data |
24b1493d | 3302 | @section @code{.data @var{subsection}} |
66b818fb RP |
3303 | |
3304 | @cindex @code{data} directive | |
f009d0ab | 3305 | @code{.data} tells @code{@value{AS}} to assemble the following statements onto the |
24b1493d RP |
3306 | end of the data subsection numbered @var{subsection} (which is an |
3307 | absolute expression). If @var{subsection} is omitted, it defaults | |
93b45514 RP |
3308 | to zero. |
3309 | ||
f009d0ab | 3310 | @ifset COFF |
242d9c06 | 3311 | @node Def |
d0281557 | 3312 | @section @code{.def @var{name}} |
66b818fb RP |
3313 | |
3314 | @cindex @code{def} directive | |
3315 | @cindex COFF symbols, debugging | |
3316 | @cindex debugging COFF symbols | |
d0281557 RP |
3317 | Begin defining debugging information for a symbol @var{name}; the |
3318 | definition extends until the @code{.endef} directive is encountered. | |
f009d0ab | 3319 | @ifset BOUT |
d0281557 | 3320 | |
f009d0ab | 3321 | This directive is only observed when @code{@value{AS}} is configured for COFF |
d0281557 RP |
3322 | format output; when producing @code{b.out}, @samp{.def} is recognized, |
3323 | but ignored. | |
f009d0ab RP |
3324 | @end ifset |
3325 | @end ifset | |
d0281557 | 3326 | |
f009d0ab | 3327 | @ifset aout-bout |
242d9c06 | 3328 | @node Desc |
f4335d56 | 3329 | @section @code{.desc @var{symbol}, @var{abs-expression}} |
66b818fb RP |
3330 | |
3331 | @cindex @code{desc} directive | |
3332 | @cindex COFF symbol descriptor | |
3333 | @cindex symbol descriptor, COFF | |
b50e59fe | 3334 | This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) |
f4335d56 | 3335 | to the low 16 bits of an absolute expression. |
93b45514 | 3336 | |
f009d0ab RP |
3337 | @ifset COFF |
3338 | The @samp{.desc} directive is not available when @code{@value{AS}} is | |
d0281557 | 3339 | configured for COFF output; it is only for @code{a.out} or @code{b.out} |
05a0e43b RP |
3340 | object format. For the sake of compatibility, @code{@value{AS}} accepts |
3341 | it, but produces no output, when configured for COFF. | |
f009d0ab RP |
3342 | @end ifset |
3343 | @end ifset | |
d0281557 | 3344 | |
f009d0ab | 3345 | @ifset COFF |
242d9c06 | 3346 | @node Dim |
d0281557 | 3347 | @section @code{.dim} |
66b818fb RP |
3348 | |
3349 | @cindex @code{dim} directive | |
3350 | @cindex COFF auxiliary symbol information | |
3351 | @cindex auxiliary symbol information, COFF | |
d0281557 RP |
3352 | This directive is generated by compilers to include auxiliary debugging |
3353 | information in the symbol table. It is only permitted inside | |
3354 | @code{.def}/@code{.endef} pairs. | |
f009d0ab | 3355 | @ifset BOUT |
d0281557 RP |
3356 | |
3357 | @samp{.dim} is only meaningful when generating COFF format output; when | |
f009d0ab | 3358 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 3359 | ignores it. |
f009d0ab RP |
3360 | @end ifset |
3361 | @end ifset | |
d0281557 | 3362 | |
242d9c06 | 3363 | @node Double |
b50e59fe | 3364 | @section @code{.double @var{flonums}} |
66b818fb RP |
3365 | |
3366 | @cindex @code{double} directive | |
3367 | @cindex floating point numbers (double) | |
d0281557 RP |
3368 | @code{.double} expects zero or more flonums, separated by commas. It |
3369 | assembles floating point numbers. | |
f009d0ab | 3370 | @ifset GENERIC |
09352a5d | 3371 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
3372 | @code{@value{AS}} is configured. @xref{Machine Dependencies}. |
3373 | @end ifset | |
3374 | @ifclear GENERIC | |
3375 | @ifset IEEEFLOAT | |
3376 | On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers | |
66b818fb | 3377 | in @sc{ieee} format. |
f009d0ab RP |
3378 | @end ifset |
3379 | @end ifclear | |
b50e59fe | 3380 | |
242d9c06 | 3381 | @node Eject |
66b818fb RP |
3382 | @section @code{.eject} |
3383 | ||
3384 | @cindex @code{eject} directive | |
3385 | @cindex new page, in listings | |
3386 | @cindex page, in listings | |
3387 | @cindex listing control: new page | |
3388 | Force a page break at this point, when generating assembly listings. | |
3389 | ||
242d9c06 | 3390 | @node Else |
b50e59fe | 3391 | @section @code{.else} |
66b818fb RP |
3392 | |
3393 | @cindex @code{else} directive | |
f009d0ab | 3394 | @code{.else} is part of the @code{@value{AS}} support for conditional |
7a4c8e5c RP |
3395 | assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section |
3396 | of code to be assembled if the condition for the preceding @code{.if} | |
3397 | was false. | |
b50e59fe | 3398 | |
1ca26844 | 3399 | @node End |
b50e59fe | 3400 | @section @code{.end} |
66b818fb RP |
3401 | |
3402 | @cindex @code{end} directive | |
1ca26844 ILT |
3403 | @code{.end} marks the end of the assembly file. @code{@value{AS}} does not |
3404 | process anything in the file past the @code{.end} directive. | |
d0281557 | 3405 | |
f009d0ab | 3406 | @ifset COFF |
242d9c06 | 3407 | @node Endef |
d0281557 | 3408 | @section @code{.endef} |
66b818fb RP |
3409 | |
3410 | @cindex @code{endef} directive | |
d0281557 | 3411 | This directive flags the end of a symbol definition begun with |
f009d0ab RP |
3412 | @code{.def}. |
3413 | @ifset BOUT | |
d0281557 RP |
3414 | |
3415 | @samp{.endef} is only meaningful when generating COFF format output; if | |
f009d0ab | 3416 | @code{@value{AS}} is configured to generate @code{b.out}, it accepts this |
d0281557 | 3417 | directive but ignores it. |
f009d0ab RP |
3418 | @end ifset |
3419 | @end ifset | |
7a4c8e5c | 3420 | |
71c2d792 DE |
3421 | @node Endfunc |
3422 | @section @code{.endfunc} | |
3423 | @cindex @code{endfunc} directive | |
3424 | @code{.endfunc} marks the end of a function specified with @code{.func}. | |
3425 | ||
242d9c06 | 3426 | @node Endif |
b50e59fe | 3427 | @section @code{.endif} |
66b818fb RP |
3428 | |
3429 | @cindex @code{endif} directive | |
f009d0ab | 3430 | @code{.endif} is part of the @code{@value{AS}} support for conditional assembly; |
b50e59fe | 3431 | it marks the end of a block of code that is only assembled |
7a4c8e5c | 3432 | conditionally. @xref{If,,@code{.if}}. |
b50e59fe | 3433 | |
242d9c06 | 3434 | @node Equ |
b50e59fe RP |
3435 | @section @code{.equ @var{symbol}, @var{expression}} |
3436 | ||
66b818fb RP |
3437 | @cindex @code{equ} directive |
3438 | @cindex assigning values to symbols | |
3439 | @cindex symbols, assigning values to | |
d0281557 | 3440 | This directive sets the value of @var{symbol} to @var{expression}. |
7a4c8e5c RP |
3441 | It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}. |
3442 | ||
9dcf8057 JL |
3443 | @ifset HPPA |
3444 | The syntax for @code{equ} on the HPPA is | |
509d5555 | 3445 | @samp{@var{symbol} .equ @var{expression}}. |
9dcf8057 JL |
3446 | @end ifset |
3447 | ||
35cfacf0 ILT |
3448 | @node Equiv |
3449 | @section @code{.equiv @var{symbol}, @var{expression}} | |
3450 | @cindex @code{equiv} directive | |
3451 | The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that | |
3452 | the assembler will signal an error if @var{symbol} is already defined. | |
3453 | ||
3454 | Except for the contents of the error message, this is roughly equivalent to | |
3455 | @smallexample | |
3456 | .ifdef SYM | |
3457 | .err | |
3458 | .endif | |
3459 | .equ SYM,VAL | |
3460 | @end smallexample | |
3461 | ||
3462 | @node Err | |
3463 | @section @code{.err} | |
3464 | @cindex @code{err} directive | |
3465 | If @code{@value{AS}} assembles a @code{.err} directive, it will print an error | |
3466 | message and, unless the @code{-Z} option was used, it will not generate an | |
3467 | object file. This can be used to signal error an conditionally compiled code. | |
3468 | ||
1ca26844 ILT |
3469 | @node Exitm |
3470 | @section @code{.exitm} | |
3471 | Exit early from the current macro definition. @xref{Macro}. | |
3472 | ||
242d9c06 | 3473 | @node Extern |
b50e59fe | 3474 | @section @code{.extern} |
66b818fb RP |
3475 | |
3476 | @cindex @code{extern} directive | |
b50e59fe | 3477 | @code{.extern} is accepted in the source program---for compatibility |
f009d0ab | 3478 | with other assemblers---but it is ignored. @code{@value{AS}} treats |
b50e59fe RP |
3479 | all undefined symbols as external. |
3480 | ||
1ca26844 ILT |
3481 | @node Fail |
3482 | @section @code{.fail @var{expression}} | |
3483 | ||
3484 | @cindex @code{fail} directive | |
3485 | Generates an error or a warning. If the value of the @var{expression} is 500 | |
3486 | or more, @code{@value{AS}} will print a warning message. If the value is less | |
3487 | than 500, @code{@value{AS}} will print an error message. The message will | |
3488 | include the value of @var{expression}. This can occasionally be useful inside | |
3489 | complex nested macros or conditional assembly. | |
3490 | ||
f009d0ab | 3491 | @ifclear no-file-dir |
242d9c06 | 3492 | @node File |
66b818fb RP |
3493 | @section @code{.file @var{string}} |
3494 | ||
3495 | @cindex @code{file} directive | |
3496 | @cindex logical file name | |
3497 | @cindex file name, logical | |
1ca26844 ILT |
3498 | @code{.file} tells @code{@value{AS}} that we are about to start a new logical |
3499 | file. @var{string} is the new file name. In general, the filename is | |
3500 | recognized whether or not it is surrounded by quotes @samp{"}; but if you wish | |
3501 | to specify an empty file name, you must give the quotes--@code{""}. This | |
3502 | statement may go away in future: it is only recognized to be compatible with | |
3503 | old @code{@value{AS}} programs. | |
f009d0ab RP |
3504 | @ifset A29K |
3505 | In some configurations of @code{@value{AS}}, @code{.file} has already been | |
3506 | removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}. | |
3507 | @end ifset | |
3508 | @end ifclear | |
7a4c8e5c | 3509 | |
242d9c06 | 3510 | @node Fill |
b50e59fe | 3511 | @section @code{.fill @var{repeat} , @var{size} , @var{value}} |
66b818fb RP |
3512 | |
3513 | @cindex @code{fill} directive | |
3514 | @cindex writing patterns in memory | |
3515 | @cindex patterns, writing in memory | |
93b45514 RP |
3516 | @var{result}, @var{size} and @var{value} are absolute expressions. |
3517 | This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} | |
3518 | may be zero or more. @var{Size} may be zero or more, but if it is | |
3519 | more than 8, then it is deemed to have the value 8, compatible with | |
3520 | other people's assemblers. The contents of each @var{repeat} bytes | |
3521 | is taken from an 8-byte number. The highest order 4 bytes are | |
3522 | zero. The lowest order 4 bytes are @var{value} rendered in the | |
f009d0ab | 3523 | byte-order of an integer on the computer @code{@value{AS}} is assembling for. |
93b45514 RP |
3524 | Each @var{size} bytes in a repetition is taken from the lowest order |
3525 | @var{size} bytes of this number. Again, this bizarre behavior is | |
3526 | compatible with other people's assemblers. | |
3527 | ||
d0281557 | 3528 | @var{size} and @var{value} are optional. |
93b45514 RP |
3529 | If the second comma and @var{value} are absent, @var{value} is |
3530 | assumed zero. If the first comma and following tokens are absent, | |
3531 | @var{size} is assumed to be 1. | |
3532 | ||
242d9c06 | 3533 | @node Float |
b50e59fe | 3534 | @section @code{.float @var{flonums}} |
66b818fb RP |
3535 | |
3536 | @cindex floating point numbers (single) | |
3537 | @cindex @code{float} directive | |
b50e59fe | 3538 | This directive assembles zero or more flonums, separated by commas. It |
d0281557 | 3539 | has the same effect as @code{.single}. |
f009d0ab | 3540 | @ifset GENERIC |
09352a5d | 3541 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
3542 | @code{@value{AS}} is configured. |
3543 | @xref{Machine Dependencies}. | |
3544 | @end ifset | |
3545 | @ifclear GENERIC | |
3546 | @ifset IEEEFLOAT | |
3547 | On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers | |
66b818fb | 3548 | in @sc{ieee} format. |
f009d0ab RP |
3549 | @end ifset |
3550 | @end ifclear | |
93b45514 | 3551 | |
71c2d792 DE |
3552 | @node Func |
3553 | @section @code{.func @var{name}[,@var{label}]} | |
3554 | @cindex @code{func} directive | |
3555 | @code{.func} emits debugging information to denote function @var{name}, and | |
3556 | is ignored unless the file is assembled with debugging enabled. | |
3557 | Only @samp{--gstabs} is currently supported. | |
3558 | @var{label} is the entry point of the function and if omitted @var{name} | |
20489f15 ILT |
3559 | prepended with the @samp{leading char} is used. |
3560 | @samp{leading char} is usually @code{_} or nothing, depending on the target. | |
71c2d792 DE |
3561 | All functions are currently defined to have @code{void} return type. |
3562 | The function must be terminated with @code{.endfunc}. | |
3563 | ||
242d9c06 | 3564 | @node Global |
b50e59fe | 3565 | @section @code{.global @var{symbol}}, @code{.globl @var{symbol}} |
66b818fb RP |
3566 | |
3567 | @cindex @code{global} directive | |
3568 | @cindex symbol, making visible to linker | |
f009d0ab | 3569 | @code{.global} makes the symbol visible to @code{@value{LD}}. If you define |
93b45514 RP |
3570 | @var{symbol} in your partial program, its value is made available to |
3571 | other partial programs that are linked with it. Otherwise, | |
05a0e43b RP |
3572 | @var{symbol} takes its attributes from a symbol of the same name |
3573 | from another file linked into the same program. | |
93b45514 | 3574 | |
b50e59fe RP |
3575 | Both spellings (@samp{.globl} and @samp{.global}) are accepted, for |
3576 | compatibility with other assemblers. | |
3577 | ||
9dcf8057 | 3578 | @ifset HPPA |
e680d737 RP |
3579 | On the HPPA, @code{.global} is not always enough to make it accessible to other |
3580 | partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. | |
3581 | @xref{HPPA Directives,, HPPA Assembler Directives}. | |
9dcf8057 JL |
3582 | @end ifset |
3583 | ||
242d9c06 | 3584 | @node hword |
d0281557 | 3585 | @section @code{.hword @var{expressions}} |
66b818fb RP |
3586 | |
3587 | @cindex @code{hword} directive | |
3588 | @cindex integers, 16-bit | |
3589 | @cindex numbers, 16-bit | |
3590 | @cindex sixteen bit integers | |
d0281557 RP |
3591 | This expects zero or more @var{expressions}, and emits |
3592 | a 16 bit number for each. | |
3593 | ||
f009d0ab | 3594 | @ifset GENERIC |
d0281557 RP |
3595 | This directive is a synonym for @samp{.short}; depending on the target |
3596 | architecture, it may also be a synonym for @samp{.word}. | |
f009d0ab RP |
3597 | @end ifset |
3598 | @ifclear GENERIC | |
3599 | @ifset W32 | |
d0281557 | 3600 | This directive is a synonym for @samp{.short}. |
f009d0ab RP |
3601 | @end ifset |
3602 | @ifset W16 | |
24b1493d | 3603 | This directive is a synonym for both @samp{.short} and @samp{.word}. |
f009d0ab RP |
3604 | @end ifset |
3605 | @end ifclear | |
d0281557 | 3606 | |
242d9c06 | 3607 | @node Ident |
b50e59fe | 3608 | @section @code{.ident} |
66b818fb RP |
3609 | |
3610 | @cindex @code{ident} directive | |
b50e59fe | 3611 | This directive is used by some assemblers to place tags in object files. |
f009d0ab | 3612 | @code{@value{AS}} simply accepts the directive for source-file |
b50e59fe RP |
3613 | compatibility with such assemblers, but does not actually emit anything |
3614 | for it. | |
3615 | ||
242d9c06 | 3616 | @node If |
b50e59fe | 3617 | @section @code{.if @var{absolute expression}} |
66b818fb RP |
3618 | |
3619 | @cindex conditional assembly | |
3620 | @cindex @code{if} directive | |
b50e59fe RP |
3621 | @code{.if} marks the beginning of a section of code which is only |
3622 | considered part of the source program being assembled if the argument | |
3623 | (which must be an @var{absolute expression}) is non-zero. The end of | |
3624 | the conditional section of code must be marked by @code{.endif} | |
7a4c8e5c | 3625 | (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the |
910d7df2 | 3626 | alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). |
b50e59fe RP |
3627 | |
3628 | The following variants of @code{.if} are also supported: | |
3629 | @table @code | |
66b818fb | 3630 | @cindex @code{ifdef} directive |
71dd3c40 | 3631 | @item .ifdef @var{symbol} |
b50e59fe RP |
3632 | Assembles the following section of code if the specified @var{symbol} |
3633 | has been defined. | |
3634 | ||
1ca26844 ILT |
3635 | @cindex @code{ifc} directive |
3636 | @item .ifc @var{string1},@var{string2} | |
3637 | Assembles the following section of code if the two strings are the same. The | |
3638 | strings may be optionally quoted with single quotes. If they are not quoted, | |
3639 | the first string stops at the first comma, and the second string stops at the | |
3640 | end of the line. Strings which contain whitespace should be quoted. The | |
3641 | string comparison is case sensitive. | |
3642 | ||
3643 | @cindex @code{ifeq} directive | |
3644 | @item .ifeq @var{absolute expression} | |
3645 | Assembles the following section of code if the argument is zero. | |
3646 | ||
66b818fb | 3647 | @cindex @code{ifeqs} directive |
1ca26844 ILT |
3648 | @item .ifeqs @var{string1},@var{string2} |
3649 | Another form of @code{.ifc}. The strings must be quoted using double quotes. | |
3650 | ||
3651 | @cindex @code{ifge} directive | |
3652 | @item .ifge @var{absolute expression} | |
3653 | Assembles the following section of code if the argument is greater than or | |
3654 | equal to zero. | |
3655 | ||
3656 | @cindex @code{ifgt} directive | |
3657 | @item .ifgt @var{absolute expression} | |
3658 | Assembles the following section of code if the argument is greater than zero. | |
3659 | ||
3660 | @cindex @code{ifle} directive | |
3661 | @item .ifle @var{absolute expression} | |
3662 | Assembles the following section of code if the argument is less than or equal | |
3663 | to zero. | |
3664 | ||
3665 | @cindex @code{iflt} directive | |
3666 | @item .iflt @var{absolute expression} | |
3667 | Assembles the following section of code if the argument is less than zero. | |
3668 | ||
3669 | @cindex @code{ifnc} directive | |
3670 | @item .ifnc @var{string1},@var{string2}. | |
3671 | Like @code{.ifc}, but the sense of the test is reversed: this assembles the | |
3672 | following section of code if the two strings are not the same. | |
b50e59fe | 3673 | |
66b818fb RP |
3674 | @cindex @code{ifndef} directive |
3675 | @cindex @code{ifnotdef} directive | |
71dd3c40 | 3676 | @item .ifndef @var{symbol} |
910d7df2 | 3677 | @itemx .ifnotdef @var{symbol} |
b50e59fe RP |
3678 | Assembles the following section of code if the specified @var{symbol} |
3679 | has not been defined. Both spelling variants are equivalent. | |
93b45514 | 3680 | |
1ca26844 ILT |
3681 | @cindex @code{ifne} directive |
3682 | @item .ifne @var{absolute expression} | |
3683 | Assembles the following section of code if the argument is not equal to zero | |
3684 | (in other words, this is equivalent to @code{.if}). | |
3685 | ||
3686 | @cindex @code{ifnes} directive | |
3687 | @item .ifnes @var{string1},@var{string2} | |
3688 | Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the | |
3689 | following section of code if the two strings are not the same. | |
b50e59fe RP |
3690 | @end table |
3691 | ||
242d9c06 | 3692 | @node Include |
b50e59fe | 3693 | @section @code{.include "@var{file}"} |
66b818fb RP |
3694 | |
3695 | @cindex @code{include} directive | |
3696 | @cindex supporting files, including | |
3697 | @cindex files, including | |
b50e59fe RP |
3698 | This directive provides a way to include supporting files at specified |
3699 | points in your source program. The code from @var{file} is assembled as | |
3700 | if it followed the point of the @code{.include}; when the end of the | |
3701 | included file is reached, assembly of the original file continues. You | |
3702 | can control the search paths used with the @samp{-I} command-line option | |
7a4c8e5c RP |
3703 | (@pxref{Invoking,,Command-Line Options}). Quotation marks are required |
3704 | around @var{file}. | |
b50e59fe | 3705 | |
242d9c06 | 3706 | @node Int |
b50e59fe | 3707 | @section @code{.int @var{expressions}} |
66b818fb RP |
3708 | |
3709 | @cindex @code{int} directive | |
f009d0ab | 3710 | @cindex integers, 32-bit |
05a0e43b RP |
3711 | Expect zero or more @var{expressions}, of any section, separated by commas. |
3712 | For each expression, emit a number that, at run time, is the value of that | |
3713 | expression. The byte order and bit size of the number depends on what kind | |
3714 | of target the assembly is for. | |
f009d0ab RP |
3715 | |
3716 | @ifclear GENERIC | |
3717 | @ifset H8 | |
8d8ddccb RP |
3718 | On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit |
3719 | integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits | |
3720 | 32-bit integers. | |
f009d0ab RP |
3721 | @end ifset |
3722 | @end ifclear | |
93b45514 | 3723 | |
95074dc3 ILT |
3724 | @node Irp |
3725 | @section @code{.irp @var{symbol},@var{values}}@dots{} | |
3726 | ||
3727 | @cindex @code{irp} directive | |
3728 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
3729 | The sequence of statements starts at the @code{.irp} directive, and is | |
3730 | terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is | |
3731 | set to @var{value}, and the sequence of statements is assembled. If no | |
3732 | @var{value} is listed, the sequence of statements is assembled once, with | |
3733 | @var{symbol} set to the null string. To refer to @var{symbol} within the | |
3734 | sequence of statements, use @var{\symbol}. | |
3735 | ||
3736 | For example, assembling | |
3737 | ||
3738 | @example | |
3739 | .irp param,1,2,3 | |
3740 | move d\param,sp@@- | |
3741 | .endr | |
3742 | @end example | |
3743 | ||
3744 | is equivalent to assembling | |
3745 | ||
3746 | @example | |
3747 | move d1,sp@@- | |
3748 | move d2,sp@@- | |
3749 | move d3,sp@@- | |
3750 | @end example | |
3751 | ||
3752 | @node Irpc | |
3753 | @section @code{.irpc @var{symbol},@var{values}}@dots{} | |
3754 | ||
3755 | @cindex @code{irpc} directive | |
3756 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
3757 | The sequence of statements starts at the @code{.irpc} directive, and is | |
3758 | terminated by an @code{.endr} directive. For each character in @var{value}, | |
3759 | @var{symbol} is set to the character, and the sequence of statements is | |
3760 | assembled. If no @var{value} is listed, the sequence of statements is | |
3761 | assembled once, with @var{symbol} set to the null string. To refer to | |
3762 | @var{symbol} within the sequence of statements, use @var{\symbol}. | |
3763 | ||
3764 | For example, assembling | |
3765 | ||
3766 | @example | |
3767 | .irpc param,123 | |
3768 | move d\param,sp@@- | |
3769 | .endr | |
3770 | @end example | |
3771 | ||
3772 | is equivalent to assembling | |
3773 | ||
3774 | @example | |
3775 | move d1,sp@@- | |
3776 | move d2,sp@@- | |
3777 | move d3,sp@@- | |
3778 | @end example | |
3779 | ||
242d9c06 | 3780 | @node Lcomm |
b50e59fe | 3781 | @section @code{.lcomm @var{symbol} , @var{length}} |
66b818fb RP |
3782 | |
3783 | @cindex @code{lcomm} directive | |
3784 | @cindex local common symbols | |
3785 | @cindex symbols, local common | |
7a4c8e5c | 3786 | Reserve @var{length} (an absolute expression) bytes for a local common |
24b1493d | 3787 | denoted by @var{symbol}. The section and value of @var{symbol} are |
7a4c8e5c | 3788 | those of the new local common. The addresses are allocated in the bss |
05a0e43b | 3789 | section, so that at run-time the bytes start off zeroed. @var{Symbol} |
7a4c8e5c | 3790 | is not declared global (@pxref{Global,,@code{.global}}), so is normally |
f009d0ab | 3791 | not visible to @code{@value{LD}}. |
93b45514 | 3792 | |
35cfacf0 ILT |
3793 | @ifset GENERIC |
3794 | Some targets permit a third argument to be used with @code{.lcomm}. This | |
3795 | argument specifies the desired alignment of the symbol in the bss section. | |
3796 | @end ifset | |
3797 | ||
9dcf8057 JL |
3798 | @ifset HPPA |
3799 | The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is | |
509d5555 | 3800 | @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. |
9dcf8057 JL |
3801 | @end ifset |
3802 | ||
242d9c06 | 3803 | @node Lflags |
66b818fb RP |
3804 | @section @code{.lflags} |
3805 | ||
3806 | @cindex @code{lflags} directive (ignored) | |
f009d0ab | 3807 | @code{@value{AS}} accepts this directive, for compatibility with other |
66b818fb RP |
3808 | assemblers, but ignores it. |
3809 | ||
f009d0ab | 3810 | @ifclear no-line-dir |
242d9c06 | 3811 | @node Line |
d0281557 | 3812 | @section @code{.line @var{line-number}} |
66b818fb RP |
3813 | |
3814 | @cindex @code{line} directive | |
f009d0ab RP |
3815 | @end ifclear |
3816 | @ifset no-line-dir | |
242d9c06 | 3817 | @node Ln |
b50e59fe | 3818 | @section @code{.ln @var{line-number}} |
66b818fb RP |
3819 | |
3820 | @cindex @code{ln} directive | |
f009d0ab | 3821 | @end ifset |
66b818fb | 3822 | @cindex logical line number |
f009d0ab | 3823 | @ifset aout-bout |
05a0e43b RP |
3824 | Change the logical line number. @var{line-number} must be an absolute |
3825 | expression. The next line has that logical line number. Therefore any other | |
3826 | statements on the current line (after a statement separator character) are | |
3827 | reported as on logical line number @var{line-number} @minus{} 1. One day | |
3828 | @code{@value{AS}} will no longer support this directive: it is recognized only | |
f009d0ab | 3829 | for compatibility with existing assembler programs. |
7a4c8e5c | 3830 | |
f009d0ab RP |
3831 | @ifset GENERIC |
3832 | @ifset A29K | |
3833 | @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is | |
65fbb2d7 | 3834 | not available; use the synonym @code{.ln} in that context. |
f009d0ab RP |
3835 | @end ifset |
3836 | @end ifset | |
3837 | @end ifset | |
d0281557 | 3838 | |
f009d0ab | 3839 | @ifclear no-line-dir |
d0281557 | 3840 | Even though this is a directive associated with the @code{a.out} or |
05a0e43b RP |
3841 | @code{b.out} object-code formats, @code{@value{AS}} still recognizes it |
3842 | when producing COFF output, and treats @samp{.line} as though it | |
d0281557 | 3843 | were the COFF @samp{.ln} @emph{if} it is found outside a |
f009d0ab | 3844 | @code{.def}/@code{.endef} pair. |
d0281557 RP |
3845 | |
3846 | Inside a @code{.def}, @samp{.line} is, instead, one of the directives | |
3847 | used by compilers to generate auxiliary symbol information for | |
3848 | debugging. | |
f009d0ab | 3849 | @end ifclear |
d0281557 | 3850 | |
910d7df2 C |
3851 | @node Linkonce |
3852 | @section @code{.linkonce [@var{type}]} | |
3853 | @cindex COMDAT | |
3854 | @cindex @code{linkonce} directive | |
3855 | @cindex common sections | |
3856 | Mark the current section so that the linker only includes a single copy of it. | |
3857 | This may be used to include the same section in several different object files, | |
3858 | but ensure that the linker will only include it once in the final output file. | |
3859 | The @code{.linkonce} pseudo-op must be used for each instance of the section. | |
3860 | Duplicate sections are detected based on the section name, so it should be | |
3861 | unique. | |
3862 | ||
3863 | This directive is only supported by a few object file formats; as of this | |
3864 | writing, the only object file format which supports it is the Portable | |
3865 | Executable format used on Windows NT. | |
3866 | ||
3867 | The @var{type} argument is optional. If specified, it must be one of the | |
3868 | following strings. For example: | |
3869 | @smallexample | |
3870 | .linkonce same_size | |
3871 | @end smallexample | |
3872 | Not all types may be supported on all object file formats. | |
3873 | ||
3874 | @table @code | |
3875 | @item discard | |
3876 | Silently discard duplicate sections. This is the default. | |
3877 | ||
3878 | @item one_only | |
3879 | Warn if there are duplicate sections, but still keep only one copy. | |
3880 | ||
3881 | @item same_size | |
3882 | Warn if any of the duplicates have different sizes. | |
3883 | ||
3884 | @item same_contents | |
3885 | Warn if any of the duplicates do not have exactly the same contents. | |
3886 | @end table | |
3887 | ||
242d9c06 | 3888 | @node Ln |
d0281557 | 3889 | @section @code{.ln @var{line-number}} |
66b818fb RP |
3890 | |
3891 | @cindex @code{ln} directive | |
f009d0ab | 3892 | @ifclear no-line-dir |
d0281557 | 3893 | @samp{.ln} is a synonym for @samp{.line}. |
f009d0ab RP |
3894 | @end ifclear |
3895 | @ifset no-line-dir | |
3896 | Tell @code{@value{AS}} to change the logical line number. @var{line-number} | |
05a0e43b | 3897 | must be an absolute expression. The next line has that logical |
7a4c8e5c | 3898 | line number, so any other statements on the current line (after a |
05a0e43b | 3899 | statement separator character @code{;}) are reported as on logical |
d0281557 | 3900 | line number @var{line-number} @minus{} 1. |
f009d0ab | 3901 | @ifset BOUT |
d0281557 | 3902 | |
f009d0ab RP |
3903 | This directive is accepted, but ignored, when @code{@value{AS}} is |
3904 | configured for @code{b.out}; its effect is only associated with COFF | |
3905 | output format. | |
3906 | @end ifset | |
3907 | @end ifset | |
d0281557 | 3908 | |
910d7df2 C |
3909 | @node MRI |
3910 | @section @code{.mri @var{val}} | |
3911 | ||
3912 | @cindex @code{mri} directive | |
3913 | @cindex MRI mode, temporarily | |
3914 | If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If | |
3915 | @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change | |
3916 | affects code assembled until the next @code{.mri} directive, or until the end | |
3917 | of the file. @xref{M, MRI mode, MRI mode}. | |
3918 | ||
242d9c06 | 3919 | @node List |
66b818fb RP |
3920 | @section @code{.list} |
3921 | ||
3922 | @cindex @code{list} directive | |
3923 | @cindex listing control, turning on | |
3924 | Control (in conjunction with the @code{.nolist} directive) whether or | |
3925 | not assembly listings are generated. These two directives maintain an | |
3926 | internal counter (which is zero initially). @code{.list} increments the | |
3927 | counter, and @code{.nolist} decrements it. Assembly listings are | |
3928 | generated whenever the counter is greater than zero. | |
3929 | ||
3930 | By default, listings are disabled. When you enable them (with the | |
3931 | @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), | |
3932 | the initial value of the listing counter is one. | |
b50e59fe | 3933 | |
242d9c06 | 3934 | @node Long |
b50e59fe | 3935 | @section @code{.long @var{expressions}} |
66b818fb RP |
3936 | |
3937 | @cindex @code{long} directive | |
7a4c8e5c | 3938 | @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}. |
93b45514 | 3939 | |
242d9c06 SC |
3940 | @ignore |
3941 | @c no one seems to know what this is for or whether this description is | |
3942 | @c what it really ought to do | |
3943 | @node Lsym | |
b50e59fe | 3944 | @section @code{.lsym @var{symbol}, @var{expression}} |
66b818fb RP |
3945 | |
3946 | @cindex @code{lsym} directive | |
3947 | @cindex symbol, not referenced in assembly | |
47342e8f | 3948 | @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in |
93b45514 RP |
3949 | the hash table, ensuring it cannot be referenced by name during the |
3950 | rest of the assembly. This sets the attributes of the symbol to be | |
47342e8f | 3951 | the same as the expression value: |
d0281557 | 3952 | @smallexample |
b50e59fe | 3953 | @var{other} = @var{descriptor} = 0 |
24b1493d | 3954 | @var{type} = @r{(section of @var{expression})} |
b50e59fe | 3955 | @var{value} = @var{expression} |
d0281557 RP |
3956 | @end smallexample |
3957 | @noindent | |
3958 | The new symbol is not flagged as external. | |
242d9c06 | 3959 | @end ignore |
93b45514 | 3960 | |
95074dc3 ILT |
3961 | @node Macro |
3962 | @section @code{.macro} | |
3963 | ||
3964 | @cindex macros | |
3965 | The commands @code{.macro} and @code{.endm} allow you to define macros that | |
3966 | generate assembly output. For example, this definition specifies a macro | |
3967 | @code{sum} that puts a sequence of numbers into memory: | |
3968 | ||
3969 | @example | |
3970 | .macro sum from=0, to=5 | |
3971 | .long \from | |
3972 | .if \to-\from | |
3973 | sum "(\from+1)",\to | |
3974 | .endif | |
3975 | .endm | |
3976 | @end example | |
3977 | ||
3978 | @noindent | |
3979 | With that definition, @samp{SUM 0,5} is equivalent to this assembly input: | |
3980 | ||
3981 | @example | |
3982 | .long 0 | |
3983 | .long 1 | |
3984 | .long 2 | |
3985 | .long 3 | |
3986 | .long 4 | |
3987 | .long 5 | |
3988 | @end example | |
3989 | ||
3990 | @ftable @code | |
3991 | @item .macro @var{macname} | |
3992 | @itemx .macro @var{macname} @var{macargs} @dots{} | |
3993 | @cindex @code{macro} directive | |
3994 | Begin the definition of a macro called @var{macname}. If your macro | |
3995 | definition requires arguments, specify their names after the macro name, | |
3996 | separated by commas or spaces. You can supply a default value for any | |
3997 | macro argument by following the name with @samp{=@var{deflt}}. For | |
3998 | example, these are all valid @code{.macro} statements: | |
3999 | ||
4000 | @table @code | |
4001 | @item .macro comm | |
4002 | Begin the definition of a macro called @code{comm}, which takes no | |
4003 | arguments. | |
4004 | ||
4005 | @item .macro plus1 p, p1 | |
4006 | @itemx .macro plus1 p p1 | |
4007 | Either statement begins the definition of a macro called @code{plus1}, | |
4008 | which takes two arguments; within the macro definition, write | |
4009 | @samp{\p} or @samp{\p1} to evaluate the arguments. | |
4010 | ||
4011 | @item .macro reserve_str p1=0 p2 | |
4012 | Begin the definition of a macro called @code{reserve_str}, with two | |
4013 | arguments. The first argument has a default value, but not the second. | |
4014 | After the definition is complete, you can call the macro either as | |
4015 | @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to | |
4016 | @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str | |
4017 | ,@var{b}} (with @samp{\p1} evaluating as the default, in this case | |
4018 | @samp{0}, and @samp{\p2} evaluating to @var{b}). | |
4019 | @end table | |
4020 | ||
4021 | When you call a macro, you can specify the argument values either by | |
4022 | position, or by keyword. For example, @samp{sum 9,17} is equivalent to | |
4023 | @samp{sum to=17, from=9}. | |
4024 | ||
4025 | @item .endm | |
4026 | @cindex @code{endm} directive | |
4027 | Mark the end of a macro definition. | |
4028 | ||
4029 | @item .exitm | |
4030 | @cindex @code{exitm} directive | |
4031 | Exit early from the current macro definition. | |
4032 | ||
4033 | @cindex number of macros executed | |
4034 | @cindex macros, count executed | |
4035 | @item \@@ | |
4036 | @code{@value{AS}} maintains a counter of how many macros it has | |
4037 | executed in this pseudo-variable; you can copy that number to your | |
4038 | output with @samp{\@@}, but @emph{only within a macro definition}. | |
4039 | ||
4040 | @ignore | |
4041 | @item LOCAL @var{name} [ , @dots{} ] | |
4042 | @emph{Warning: @code{LOCAL} is only available if you select ``alternate | |
4043 | macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,, | |
4044 | Alternate macro syntax}. | |
4045 | ||
4046 | Generate a string replacement for each of the @var{name} arguments, and | |
4047 | replace any instances of @var{name} in each macro expansion. The | |
4048 | replacement string is unique in the assembly, and different for each | |
4049 | separate macro expansion. @code{LOCAL} allows you to write macros that | |
4050 | define symbols, without fear of conflict between separate macro expansions. | |
4051 | @end ignore | |
4052 | @end ftable | |
4053 | ||
242d9c06 | 4054 | @node Nolist |
66b818fb RP |
4055 | @section @code{.nolist} |
4056 | ||
4057 | @cindex @code{nolist} directive | |
4058 | @cindex listing control, turning off | |
4059 | Control (in conjunction with the @code{.list} directive) whether or | |
4060 | not assembly listings are generated. These two directives maintain an | |
4061 | internal counter (which is zero initially). @code{.list} increments the | |
4062 | counter, and @code{.nolist} decrements it. Assembly listings are | |
4063 | generated whenever the counter is greater than zero. | |
4064 | ||
242d9c06 | 4065 | @node Octa |
b50e59fe | 4066 | @section @code{.octa @var{bignums}} |
66b818fb RP |
4067 | |
4068 | @c FIXME: double size emitted for "octa" on i960, others? Or warn? | |
4069 | @cindex @code{octa} directive | |
4070 | @cindex integer, 16-byte | |
4071 | @cindex sixteen byte integer | |
47342e8f | 4072 | This directive expects zero or more bignums, separated by commas. For each |
b50e59fe RP |
4073 | bignum, it emits a 16-byte integer. |
4074 | ||
d0281557 RP |
4075 | The term ``octa'' comes from contexts in which a ``word'' is two bytes; |
4076 | hence @emph{octa}-word for 16 bytes. | |
93b45514 | 4077 | |
242d9c06 | 4078 | @node Org |
b50e59fe | 4079 | @section @code{.org @var{new-lc} , @var{fill}} |
47342e8f | 4080 | |
66b818fb RP |
4081 | @cindex @code{org} directive |
4082 | @cindex location counter, advancing | |
4083 | @cindex advancing location counter | |
4084 | @cindex current address, advancing | |
05a0e43b | 4085 | Advance the location counter of the current section to |
93b45514 | 4086 | @var{new-lc}. @var{new-lc} is either an absolute expression or an |
24b1493d RP |
4087 | expression with the same section as the current subsection. That is, |
4088 | you can't use @code{.org} to cross sections: if @var{new-lc} has the | |
4089 | wrong section, the @code{.org} directive is ignored. To be compatible | |
4090 | with former assemblers, if the section of @var{new-lc} is absolute, | |
05a0e43b | 4091 | @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc} |
24b1493d | 4092 | is the same as the current subsection. |
47342e8f RP |
4093 | |
4094 | @code{.org} may only increase the location counter, or leave it | |
4095 | unchanged; you cannot use @code{.org} to move the location counter | |
d0281557 | 4096 | backwards. |
47342e8f | 4097 | |
b50e59fe RP |
4098 | @c double negative used below "not undefined" because this is a specific |
4099 | @c reference to "undefined" (as SEG_UNKNOWN is called in this manual) | |
71dd3c40 | 4100 | @c section. doc@cygnus.com 18feb91 |
dd565f85 | 4101 | Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc} |
b50e59fe | 4102 | may not be undefined. If you really detest this restriction we eagerly await |
d0281557 | 4103 | a chance to share your improved assembler. |
93b45514 | 4104 | |
24b1493d RP |
4105 | Beware that the origin is relative to the start of the section, not |
4106 | to the start of the subsection. This is compatible with other | |
93b45514 RP |
4107 | people's assemblers. |
4108 | ||
24b1493d | 4109 | When the location counter (of the current subsection) is advanced, the |
93b45514 RP |
4110 | intervening bytes are filled with @var{fill} which should be an |
4111 | absolute expression. If the comma and @var{fill} are omitted, | |
4112 | @var{fill} defaults to zero. | |
4113 | ||
931a8fab | 4114 | @node P2align |
c6c7035c | 4115 | @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
931a8fab KR |
4116 | |
4117 | @cindex padding the location counter given a power of two | |
4118 | @cindex @code{p2align} directive | |
4119 | Pad the location counter (in the current subsection) to a particular | |
4120 | storage boundary. The first expression (which must be absolute) is the | |
4121 | number of low-order zero bits the location counter must have after | |
4122 | advancement. For example @samp{.p2align 3} advances the location | |
4123 | counter until it a multiple of 8. If the location counter is already a | |
4124 | multiple of 8, no change is needed. | |
4125 | ||
c6c7035c MM |
4126 | The second expression (also absolute) gives the fill value to be stored in the |
4127 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4128 | padding bytes are normally zero. However, on some systems, if the section is | |
4129 | marked as containing code and the fill value is omitted, the space is filled | |
4130 | with no-op instructions. | |
4131 | ||
4132 | The third expression is also absolute, and is also optional. If it is present, | |
4133 | it is the maximum number of bytes that should be skipped by this alignment | |
4134 | directive. If doing the alignment would require skipping more bytes than the | |
4135 | specified maximum, then the alignment is not done at all. You can omit the | |
4136 | fill value (the second argument) entirely by simply using two commas after the | |
4137 | required alignment; this can be useful if you want the alignment to be filled | |
4138 | with no-op instructions when appropriate. | |
931a8fab | 4139 | |
71dd3c40 ILT |
4140 | @cindex @code{p2alignw} directive |
4141 | @cindex @code{p2alignl} directive | |
4142 | The @code{.p2alignw} and @code{.p2alignl} directives are variants of the | |
4143 | @code{.p2align} directive. The @code{.p2alignw} directive treats the fill | |
4144 | pattern as a two byte word value. The @code{.p2alignl} directives treats the | |
4145 | fill pattern as a four byte longword value. For example, @code{.p2alignw | |
4146 | 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
4147 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
4148 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
4149 | undefined. | |
4150 | ||
1ca26844 ILT |
4151 | @node Print |
4152 | @section @code{.print @var{string}} | |
4153 | ||
4154 | @cindex @code{print} directive | |
4155 | @code{@value{AS}} will print @var{string} on the standard output during | |
4156 | assembly. You must put @var{string} in double quotes. | |
4157 | ||
242d9c06 | 4158 | @node Psize |
66b818fb RP |
4159 | @section @code{.psize @var{lines} , @var{columns}} |
4160 | ||
4161 | @cindex @code{psize} directive | |
4162 | @cindex listing control: paper size | |
4163 | @cindex paper size, for listings | |
4164 | Use this directive to declare the number of lines---and, optionally, the | |
f009d0ab | 4165 | number of columns---to use for each page, when generating listings. |
66b818fb | 4166 | |
05a0e43b | 4167 | If you do not use @code{.psize}, listings use a default line-count |
66b818fb RP |
4168 | of 60. You may omit the comma and @var{columns} specification; the |
4169 | default width is 200 columns. | |
4170 | ||
05a0e43b | 4171 | @code{@value{AS}} generates formfeeds whenever the specified number of |
66b818fb | 4172 | lines is exceeded (or whenever you explicitly request one, using |
f009d0ab | 4173 | @code{.eject}). |
66b818fb RP |
4174 | |
4175 | If you specify @var{lines} as @code{0}, no formfeeds are generated save | |
4176 | those explicitly specified with @code{.eject}. | |
4177 | ||
1ca26844 ILT |
4178 | @node Purgem |
4179 | @section @code{.purgem @var{name}} | |
4180 | ||
4181 | @cindex @code{purgem} directive | |
4182 | Undefine the macro @var{name}, so that later uses of the string will not be | |
4183 | expanded. @xref{Macro}. | |
4184 | ||
242d9c06 | 4185 | @node Quad |
b50e59fe | 4186 | @section @code{.quad @var{bignums}} |
66b818fb RP |
4187 | |
4188 | @cindex @code{quad} directive | |
b50e59fe | 4189 | @code{.quad} expects zero or more bignums, separated by commas. For |
d0281557 | 4190 | each bignum, it emits |
f009d0ab RP |
4191 | @ifclear bignum-16 |
4192 | an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a | |
4193 | warning message; and just takes the lowest order 8 bytes of the bignum. | |
66b818fb RP |
4194 | @cindex eight-byte integer |
4195 | @cindex integer, 8-byte | |
b50e59fe | 4196 | |
d0281557 | 4197 | The term ``quad'' comes from contexts in which a ``word'' is two bytes; |
b50e59fe | 4198 | hence @emph{quad}-word for 8 bytes. |
f009d0ab RP |
4199 | @end ifclear |
4200 | @ifset bignum-16 | |
d0281557 | 4201 | a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a |
f009d0ab | 4202 | warning message; and just takes the lowest order 16 bytes of the bignum. |
66b818fb RP |
4203 | @cindex sixteen-byte integer |
4204 | @cindex integer, 16-byte | |
f009d0ab | 4205 | @end ifset |
d0281557 | 4206 | |
95074dc3 ILT |
4207 | @node Rept |
4208 | @section @code{.rept @var{count}} | |
4209 | ||
4210 | @cindex @code{rept} directive | |
4211 | Repeat the sequence of lines between the @code{.rept} directive and the next | |
4212 | @code{.endr} directive @var{count} times. | |
4213 | ||
4214 | For example, assembling | |
4215 | ||
4216 | @example | |
4217 | .rept 3 | |
4218 | .long 0 | |
4219 | .endr | |
4220 | @end example | |
4221 | ||
4222 | is equivalent to assembling | |
4223 | ||
4224 | @example | |
4225 | .long 0 | |
4226 | .long 0 | |
4227 | .long 0 | |
4228 | @end example | |
4229 | ||
242d9c06 | 4230 | @node Sbttl |
66b818fb RP |
4231 | @section @code{.sbttl "@var{subheading}"} |
4232 | ||
4233 | @cindex @code{sbttl} directive | |
4234 | @cindex subtitles for listings | |
4235 | @cindex listing control: subtitle | |
4236 | Use @var{subheading} as the title (third line, immediately after the | |
f009d0ab | 4237 | title line) when generating assembly listings. |
66b818fb RP |
4238 | |
4239 | This directive affects subsequent pages, as well as the current page if | |
4240 | it appears within ten lines of the top of a page. | |
4241 | ||
f009d0ab | 4242 | @ifset COFF |
242d9c06 | 4243 | @node Scl |
d0281557 | 4244 | @section @code{.scl @var{class}} |
66b818fb RP |
4245 | |
4246 | @cindex @code{scl} directive | |
4247 | @cindex symbol storage class (COFF) | |
4248 | @cindex COFF symbol storage class | |
d0281557 RP |
4249 | Set the storage-class value for a symbol. This directive may only be |
4250 | used inside a @code{.def}/@code{.endef} pair. Storage class may flag | |
4251 | whether a symbol is static or external, or it may record further | |
4252 | symbolic debugging information. | |
f009d0ab | 4253 | @ifset BOUT |
d0281557 RP |
4254 | |
4255 | The @samp{.scl} directive is primarily associated with COFF output; when | |
05a0e43b RP |
4256 | configured to generate @code{b.out} output format, @code{@value{AS}} |
4257 | accepts this directive but ignores it. | |
f009d0ab RP |
4258 | @end ifset |
4259 | @end ifset | |
d0281557 | 4260 | |
242d9c06 | 4261 | @node Section |
868c3513 | 4262 | @section @code{.section @var{name}} |
66b818fb RP |
4263 | |
4264 | @cindex @code{section} directive | |
868c3513 ILT |
4265 | @cindex named section |
4266 | Use the @code{.section} directive to assemble the following code into a section | |
4267 | named @var{name}. | |
4268 | ||
4b9f4409 KR |
4269 | This directive is only supported for targets that actually support arbitrarily |
4270 | named sections; on @code{a.out} targets, for example, it is not accepted, even | |
868c3513 ILT |
4271 | with a standard @code{a.out} section name. |
4272 | ||
4273 | @ifset COFF | |
4274 | For COFF targets, the @code{.section} directive is used in one of the following | |
4275 | ways: | |
4276 | @smallexample | |
4277 | .section @var{name}[, "@var{flags}"] | |
4278 | .section @var{name}[, @var{subsegment}] | |
4279 | @end smallexample | |
4280 | ||
4281 | If the optional argument is quoted, it is taken as flags to use for the | |
4282 | section. Each flag is a single character. The following flags are recognized: | |
4283 | @table @code | |
4284 | @item b | |
4285 | bss section (uninitialized data) | |
4286 | @item n | |
4287 | section is not loaded | |
4288 | @item w | |
4289 | writable section | |
4290 | @item d | |
4291 | data section | |
35cfacf0 ILT |
4292 | @item r |
4293 | read-only section | |
868c3513 ILT |
4294 | @item x |
4295 | executable section | |
4296 | @end table | |
4297 | ||
4298 | If no flags are specified, the default flags depend upon the section name. If | |
4299 | the section name is not recognized, the default will be for the section to be | |
4300 | loaded and writable. | |
4301 | ||
4302 | If the optional argument to the @code{.section} directive is not quoted, it is | |
4303 | taken as a subsegment number (@pxref{Sub-Sections}). | |
4b9f4409 | 4304 | @end ifset |
868c3513 ILT |
4305 | |
4306 | @ifset ELF | |
4307 | For ELF targets, the @code{.section} directive is used like this: | |
4308 | @smallexample | |
4309 | .section @var{name}[, "@var{flags}"[, @@@var{type}]] | |
4310 | @end smallexample | |
4311 | The optional @var{flags} argument is a quoted string which may contain any | |
4312 | combintion of the following characters: | |
4313 | @table @code | |
4314 | @item a | |
4315 | section is allocatable | |
4316 | @item w | |
4317 | section is writable | |
4318 | @item x | |
4319 | section is executable | |
4320 | @end table | |
4321 | ||
4322 | The optional @var{type} argument may contain one of the following constants: | |
4323 | @table @code | |
4324 | @item @@progbits | |
4325 | section contains data | |
4326 | @item @@nobits | |
4327 | section does not contain data (i.e., section only occupies space) | |
4328 | @end table | |
4329 | ||
4330 | If no flags are specified, the default flags depend upon the section name. If | |
4331 | the section name is not recognized, the default will be for the section to have | |
4332 | none of the above flags: it will not be allocated in memory, nor writable, nor | |
4333 | executable. The section will contain data. | |
4334 | ||
4335 | For ELF targets, the assembler supports another type of @code{.section} | |
4336 | directive for compatibility with the Solaris assembler: | |
4337 | @smallexample | |
4338 | .section "@var{name}"[, @var{flags}...] | |
4339 | @end smallexample | |
4340 | Note that the section name is quoted. There may be a sequence of comma | |
4341 | separated flags: | |
4342 | @table @code | |
4343 | @item #alloc | |
4344 | section is allocatable | |
4345 | @item #write | |
4346 | section is writable | |
4347 | @item #execinstr | |
4348 | section is executable | |
4349 | @end table | |
f009d0ab | 4350 | @end ifset |
242d9c06 SC |
4351 | |
4352 | @node Set | |
b50e59fe | 4353 | @section @code{.set @var{symbol}, @var{expression}} |
93b45514 | 4354 | |
66b818fb RP |
4355 | @cindex @code{set} directive |
4356 | @cindex symbol value, setting | |
05a0e43b RP |
4357 | Set the value of @var{symbol} to @var{expression}. This |
4358 | changes @var{symbol}'s value and type to conform to | |
d0281557 | 4359 | @var{expression}. If @var{symbol} was flagged as external, it remains |
c6c7035c | 4360 | flagged (@pxref{Symbol Attributes}). |
93b45514 | 4361 | |
47342e8f | 4362 | You may @code{.set} a symbol many times in the same assembly. |
93b45514 RP |
4363 | |
4364 | If you @code{.set} a global symbol, the value stored in the object | |
4365 | file is the last value stored into it. | |
4366 | ||
9dcf8057 JL |
4367 | @ifset HPPA |
4368 | The syntax for @code{set} on the HPPA is | |
509d5555 | 4369 | @samp{@var{symbol} .set @var{expression}}. |
9dcf8057 JL |
4370 | @end ifset |
4371 | ||
242d9c06 | 4372 | @node Short |
b50e59fe | 4373 | @section @code{.short @var{expressions}} |
66b818fb RP |
4374 | |
4375 | @cindex @code{short} directive | |
f009d0ab RP |
4376 | @ifset GENERIC |
4377 | @code{.short} is normally the same as @samp{.word}. | |
4378 | @xref{Word,,@code{.word}}. | |
4379 | ||
7a4c8e5c | 4380 | In some configurations, however, @code{.short} and @code{.word} generate |
f009d0ab RP |
4381 | numbers of different lengths; @pxref{Machine Dependencies}. |
4382 | @end ifset | |
4383 | @ifclear GENERIC | |
4384 | @ifset W16 | |
4385 | @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. | |
4386 | @end ifset | |
4387 | @ifset W32 | |
b50e59fe RP |
4388 | This expects zero or more @var{expressions}, and emits |
4389 | a 16 bit number for each. | |
f009d0ab RP |
4390 | @end ifset |
4391 | @end ifclear | |
242d9c06 SC |
4392 | |
4393 | @node Single | |
b50e59fe | 4394 | @section @code{.single @var{flonums}} |
66b818fb RP |
4395 | |
4396 | @cindex @code{single} directive | |
4397 | @cindex floating point numbers (single) | |
b50e59fe | 4398 | This directive assembles zero or more flonums, separated by commas. It |
d0281557 | 4399 | has the same effect as @code{.float}. |
f009d0ab | 4400 | @ifset GENERIC |
09352a5d | 4401 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
4402 | @code{@value{AS}} is configured. @xref{Machine Dependencies}. |
4403 | @end ifset | |
4404 | @ifclear GENERIC | |
4405 | @ifset IEEEFLOAT | |
4406 | On the @value{TARGET} family, @code{.single} emits 32-bit floating point | |
66b818fb | 4407 | numbers in @sc{ieee} format. |
f009d0ab RP |
4408 | @end ifset |
4409 | @end ifclear | |
d0281557 | 4410 | |
f009d0ab | 4411 | @ifset COFF |
242d9c06 | 4412 | @node Size |
d0281557 | 4413 | @section @code{.size} |
66b818fb RP |
4414 | |
4415 | @cindex @code{size} directive | |
d0281557 RP |
4416 | This directive is generated by compilers to include auxiliary debugging |
4417 | information in the symbol table. It is only permitted inside | |
4418 | @code{.def}/@code{.endef} pairs. | |
f009d0ab | 4419 | @ifset BOUT |
d0281557 RP |
4420 | |
4421 | @samp{.size} is only meaningful when generating COFF format output; when | |
f009d0ab | 4422 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 4423 | ignores it. |
f009d0ab RP |
4424 | @end ifset |
4425 | @end ifset | |
7a4c8e5c | 4426 | |
3ffb03b1 DE |
4427 | @node Sleb128 |
4428 | @section @code{.sleb128 @var{expressions}} | |
4429 | ||
4430 | @cindex @code{sleb128} directive | |
4431 | @var{sleb128} stands for ``signed little endian base 128.'' This is a | |
4432 | compact, variable length representation of numbers used by the DWARF | |
4433 | symbolic debugging format. @xref{Uleb128,@code{.uleb128}}. | |
4434 | ||
f009d0ab | 4435 | @ifclear no-space-dir |
910d7df2 C |
4436 | @node Skip |
4437 | @section @code{.skip @var{size} , @var{fill}} | |
4438 | ||
4439 | @cindex @code{skip} directive | |
4440 | @cindex filling memory | |
4441 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
4442 | @var{size} and @var{fill} are absolute expressions. If the comma and | |
4443 | @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as | |
4444 | @samp{.space}. | |
4445 | ||
242d9c06 | 4446 | @node Space |
b50e59fe | 4447 | @section @code{.space @var{size} , @var{fill}} |
66b818fb RP |
4448 | |
4449 | @cindex @code{space} directive | |
4450 | @cindex filling memory | |
47342e8f | 4451 | This directive emits @var{size} bytes, each of value @var{fill}. Both |
93b45514 | 4452 | @var{size} and @var{fill} are absolute expressions. If the comma |
910d7df2 C |
4453 | and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same |
4454 | as @samp{.skip}. | |
05a0e43b RP |
4455 | |
4456 | @ifset HPPA | |
4457 | @quotation | |
4458 | @emph{Warning:} @code{.space} has a completely different meaning for HPPA | |
e680d737 RP |
4459 | targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 |
4460 | Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the | |
4461 | @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, | |
4462 | for a summary. | |
05a0e43b RP |
4463 | @end quotation |
4464 | @end ifset | |
f009d0ab | 4465 | @end ifclear |
b50e59fe | 4466 | |
f009d0ab RP |
4467 | @ifset A29K |
4468 | @ifclear GENERIC | |
4469 | @node Space | |
24b1493d | 4470 | @section @code{.space} |
66b818fb | 4471 | @cindex @code{space} directive |
f009d0ab | 4472 | @end ifclear |
7a4c8e5c RP |
4473 | On the AMD 29K, this directive is ignored; it is accepted for |
4474 | compatibility with other AMD 29K assemblers. | |
b50e59fe RP |
4475 | |
4476 | @quotation | |
8babef85 | 4477 | @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive |
f009d0ab | 4478 | @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}. |
b50e59fe | 4479 | @end quotation |
f009d0ab | 4480 | @end ifset |
93b45514 | 4481 | |
f009d0ab | 4482 | @ifset have-stabs |
242d9c06 | 4483 | @node Stab |
b50e59fe | 4484 | @section @code{.stabd, .stabn, .stabs} |
66b818fb RP |
4485 | |
4486 | @cindex symbolic debuggers, information for | |
4487 | @cindex @code{stab@var{x}} directives | |
47342e8f | 4488 | There are three directives that begin @samp{.stab}. |
b50e59fe | 4489 | All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. |
f009d0ab | 4490 | The symbols are not entered in the @code{@value{AS}} hash table: they |
d0281557 | 4491 | cannot be referenced elsewhere in the source file. |
93b45514 | 4492 | Up to five fields are required: |
f009d0ab | 4493 | |
93b45514 RP |
4494 | @table @var |
4495 | @item string | |
f009d0ab RP |
4496 | This is the symbol's name. It may contain any character except |
4497 | @samp{\000}, so is more general than ordinary symbol names. Some | |
4498 | debuggers used to code arbitrarily complex structures into symbol names | |
4499 | using this field. | |
4500 | ||
93b45514 | 4501 | @item type |
f009d0ab RP |
4502 | An absolute expression. The symbol's type is set to the low 8 bits of |
4503 | this expression. Any bit pattern is permitted, but @code{@value{LD}} | |
05a0e43b | 4504 | and debuggers choke on silly bit patterns. |
f009d0ab | 4505 | |
93b45514 | 4506 | @item other |
f009d0ab RP |
4507 | An absolute expression. The symbol's ``other'' attribute is set to the |
4508 | low 8 bits of this expression. | |
4509 | ||
93b45514 | 4510 | @item desc |
f009d0ab RP |
4511 | An absolute expression. The symbol's descriptor is set to the low 16 |
4512 | bits of this expression. | |
4513 | ||
93b45514 | 4514 | @item value |
b50e59fe | 4515 | An absolute expression which becomes the symbol's value. |
93b45514 RP |
4516 | @end table |
4517 | ||
b50e59fe | 4518 | If a warning is detected while reading a @code{.stabd}, @code{.stabn}, |
05a0e43b RP |
4519 | or @code{.stabs} statement, the symbol has probably already been created; |
4520 | you get a half-formed symbol in your object file. This is | |
b50e59fe | 4521 | compatible with earlier assemblers! |
93b45514 | 4522 | |
47342e8f | 4523 | @table @code |
66b818fb | 4524 | @cindex @code{stabd} directive |
47342e8f | 4525 | @item .stabd @var{type} , @var{other} , @var{desc} |
93b45514 RP |
4526 | |
4527 | The ``name'' of the symbol generated is not even an empty string. | |
4528 | It is a null pointer, for compatibility. Older assemblers used a | |
4529 | null pointer so they didn't waste space in object files with empty | |
4530 | strings. | |
4531 | ||
b50e59fe | 4532 | The symbol's value is set to the location counter, |
93b45514 | 4533 | relocatably. When your program is linked, the value of this symbol |
05a0e43b | 4534 | is the address of the location counter when the @code{.stabd} was |
93b45514 RP |
4535 | assembled. |
4536 | ||
66b818fb | 4537 | @cindex @code{stabn} directive |
71dd3c40 | 4538 | @item .stabn @var{type} , @var{other} , @var{desc} , @var{value} |
93b45514 RP |
4539 | The name of the symbol is set to the empty string @code{""}. |
4540 | ||
66b818fb | 4541 | @cindex @code{stabs} directive |
71dd3c40 | 4542 | @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} |
47342e8f RP |
4543 | All five fields are specified. |
4544 | @end table | |
f009d0ab RP |
4545 | @end ifset |
4546 | @c end have-stabs | |
d0281557 | 4547 | |
e680d737 RP |
4548 | @node String |
4549 | @section @code{.string} "@var{str}" | |
4550 | ||
4551 | @cindex string, copying to object file | |
4552 | @cindex @code{string} directive | |
4553 | ||
4554 | Copy the characters in @var{str} to the object file. You may specify more than | |
4555 | one string to copy, separated by commas. Unless otherwise specified for a | |
4556 | particular machine, the assembler marks the end of each string with a 0 byte. | |
81fcb3ff | 4557 | You can use any of the escape sequences described in @ref{Strings,,Strings}. |
e680d737 | 4558 | |
1ca26844 ILT |
4559 | @node Struct |
4560 | @section @code{.struct @var{expression}} | |
4561 | ||
4562 | @cindex @code{struct} directive | |
4563 | Switch to the absolute section, and set the section offset to @var{expression}, | |
4564 | which must be an absolute expression. You might use this as follows: | |
4565 | @smallexample | |
4566 | .struct 0 | |
4567 | field1: | |
4568 | .struct field1 + 4 | |
4569 | field2: | |
4570 | .struct field2 + 4 | |
4571 | field3: | |
4572 | @end smallexample | |
4573 | This would define the symbol @code{field1} to have the value 0, the symbol | |
4574 | @code{field2} to have the value 4, and the symbol @code{field3} to have the | |
4575 | value 8. Assembly would be left in the absolute section, and you would need to | |
4576 | use a @code{.section} directive of some sort to change to some other section | |
4577 | before further assembly. | |
4578 | ||
35cfacf0 ILT |
4579 | @ifset ELF |
4580 | @node Symver | |
4581 | @section @code{.symver} | |
4582 | @cindex @code{symver} directive | |
4583 | @cindex symbol versioning | |
4584 | @cindex versions of symbols | |
4585 | Use the @code{.symver} directive to bind symbols to specific version nodes | |
4586 | within a source file. This is only supported on ELF platforms, and is | |
4587 | typically used when assembling files to be linked into a shared library. | |
4588 | There are cases where it may make sense to use this in objects to be bound | |
4589 | into an application itself so as to override a versioned symbol from a | |
4590 | shared library. | |
4591 | ||
4592 | For ELF targets, the @code{.symver} directive is used like this: | |
4593 | @smallexample | |
4594 | .symver @var{name}, @var{name2@@nodename} | |
4595 | @end smallexample | |
4596 | In this case, the symbol @var{name} must exist and be defined within the file | |
4597 | being assembled. The @code{.versym} directive effectively creates a symbol | |
4598 | alias with the name @var{name2@@nodename}, and in fact the main reason that we | |
4599 | just don't try and create a regular alias is that the @var{@@} character isn't | |
4600 | permitted in symbol names. The @var{name2} part of the name is the actual name | |
4601 | of the symbol by which it will be externally referenced. The name @var{name} | |
4602 | itself is merely a name of convenience that is used so that it is possible to | |
4603 | have definitions for multiple versions of a function within a single source | |
4604 | file, and so that the compiler can unambiguously know which version of a | |
4605 | function is being mentioned. The @var{nodename} portion of the alias should be | |
4606 | the name of a node specified in the version script supplied to the linker when | |
4607 | building a shared library. If you are attempting to override a versioned | |
4608 | symbol from a shared library, then @var{nodename} should correspond to the | |
4609 | nodename of the symbol you are trying to override. | |
4610 | @end ifset | |
4611 | ||
f009d0ab | 4612 | @ifset COFF |
242d9c06 | 4613 | @node Tag |
d0281557 | 4614 | @section @code{.tag @var{structname}} |
66b818fb RP |
4615 | |
4616 | @cindex COFF structure debugging | |
4617 | @cindex structure debugging, COFF | |
4618 | @cindex @code{tag} directive | |
d0281557 RP |
4619 | This directive is generated by compilers to include auxiliary debugging |
4620 | information in the symbol table. It is only permitted inside | |
4621 | @code{.def}/@code{.endef} pairs. Tags are used to link structure | |
4622 | definitions in the symbol table with instances of those structures. | |
f009d0ab | 4623 | @ifset BOUT |
d0281557 RP |
4624 | |
4625 | @samp{.tag} is only used when generating COFF format output; when | |
f009d0ab | 4626 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 4627 | ignores it. |
f009d0ab RP |
4628 | @end ifset |
4629 | @end ifset | |
7a4c8e5c | 4630 | |
242d9c06 | 4631 | @node Text |
24b1493d | 4632 | @section @code{.text @var{subsection}} |
66b818fb RP |
4633 | |
4634 | @cindex @code{text} directive | |
f009d0ab | 4635 | Tells @code{@value{AS}} to assemble the following statements onto the end of |
24b1493d RP |
4636 | the text subsection numbered @var{subsection}, which is an absolute |
4637 | expression. If @var{subsection} is omitted, subsection number zero | |
93b45514 RP |
4638 | is used. |
4639 | ||
242d9c06 | 4640 | @node Title |
66b818fb RP |
4641 | @section @code{.title "@var{heading}"} |
4642 | ||
4643 | @cindex @code{title} directive | |
4644 | @cindex listing control: title line | |
4645 | Use @var{heading} as the title (second line, immediately after the | |
f009d0ab | 4646 | source file name and pagenumber) when generating assembly listings. |
66b818fb RP |
4647 | |
4648 | This directive affects subsequent pages, as well as the current page if | |
4649 | it appears within ten lines of the top of a page. | |
4650 | ||
f009d0ab | 4651 | @ifset COFF |
242d9c06 | 4652 | @node Type |
d0281557 | 4653 | @section @code{.type @var{int}} |
66b818fb RP |
4654 | |
4655 | @cindex COFF symbol type | |
4656 | @cindex symbol type, COFF | |
4657 | @cindex @code{type} directive | |
d0281557 RP |
4658 | This directive, permitted only within @code{.def}/@code{.endef} pairs, |
4659 | records the integer @var{int} as the type attribute of a symbol table entry. | |
f009d0ab | 4660 | @ifset BOUT |
d0281557 RP |
4661 | |
4662 | @samp{.type} is associated only with COFF format output; when | |
f009d0ab | 4663 | @code{@value{AS}} is configured for @code{b.out} output, it accepts this |
d0281557 | 4664 | directive but ignores it. |
f009d0ab RP |
4665 | @end ifset |
4666 | @end ifset | |
d0281557 | 4667 | |
f009d0ab | 4668 | @ifset COFF |
242d9c06 | 4669 | @node Val |
d0281557 | 4670 | @section @code{.val @var{addr}} |
66b818fb RP |
4671 | |
4672 | @cindex @code{val} directive | |
4673 | @cindex COFF value attribute | |
4674 | @cindex value attribute, COFF | |
d0281557 RP |
4675 | This directive, permitted only within @code{.def}/@code{.endef} pairs, |
4676 | records the address @var{addr} as the value attribute of a symbol table | |
4677 | entry. | |
f009d0ab | 4678 | @ifset BOUT |
d0281557 | 4679 | |
f009d0ab | 4680 | @samp{.val} is used only for COFF output; when @code{@value{AS}} is |
d0281557 | 4681 | configured for @code{b.out}, it accepts this directive but ignores it. |
f009d0ab RP |
4682 | @end ifset |
4683 | @end ifset | |
7a4c8e5c | 4684 | |
3ffb03b1 DE |
4685 | @node Uleb128 |
4686 | @section @code{.uleb128 @var{expressions}} | |
4687 | ||
4688 | @cindex @code{uleb128} directive | |
4689 | @var{uleb128} stands for ``unsigned little endian base 128.'' This is a | |
4690 | compact, variable length representation of numbers used by the DWARF | |
4691 | symbolic debugging format. @xref{Sleb128,@code{.sleb128}}. | |
4692 | ||
242d9c06 | 4693 | @node Word |
b50e59fe | 4694 | @section @code{.word @var{expressions}} |
66b818fb RP |
4695 | |
4696 | @cindex @code{word} directive | |
24b1493d | 4697 | This directive expects zero or more @var{expressions}, of any section, |
b50e59fe | 4698 | separated by commas. |
f009d0ab RP |
4699 | @ifclear GENERIC |
4700 | @ifset W32 | |
4701 | For each expression, @code{@value{AS}} emits a 32-bit number. | |
4702 | @end ifset | |
4703 | @ifset W16 | |
4704 | For each expression, @code{@value{AS}} emits a 16-bit number. | |
4705 | @end ifset | |
4706 | @end ifclear | |
4707 | @ifset GENERIC | |
4708 | ||
0b5b143a | 4709 | The size of the number emitted, and its byte order, |
05a0e43b | 4710 | depend on what target computer the assembly is for. |
f009d0ab | 4711 | @end ifset |
09352a5d | 4712 | |
7a4c8e5c | 4713 | @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't |
09352a5d | 4714 | @c happen---32-bit addressability, period; no long/short jumps. |
f009d0ab | 4715 | @ifset DIFF-TBL-KLUGE |
66b818fb RP |
4716 | @cindex difference tables altered |
4717 | @cindex altered difference tables | |
0b5b143a RP |
4718 | @quotation |
4719 | @emph{Warning: Special Treatment to support Compilers} | |
4720 | @end quotation | |
47342e8f | 4721 | |
f009d0ab | 4722 | @ifset GENERIC |
24b1493d RP |
4723 | Machines with a 32-bit address space, but that do less than 32-bit |
4724 | addressing, require the following special treatment. If the machine of | |
4725 | interest to you does 32-bit addressing (or doesn't require it; | |
f009d0ab | 4726 | @pxref{Machine Dependencies}), you can ignore this issue. |
7a4c8e5c | 4727 | |
f009d0ab | 4728 | @end ifset |
05a0e43b RP |
4729 | In order to assemble compiler output into something that works, |
4730 | @code{@value{AS}} occasionlly does strange things to @samp{.word} directives. | |
47342e8f | 4731 | Directives of the form @samp{.word sym1-sym2} are often emitted by |
f009d0ab | 4732 | compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a |
47342e8f | 4733 | directive of the form @samp{.word sym1-sym2}, and the difference between |
05a0e43b RP |
4734 | @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}} |
4735 | creates a @dfn{secondary jump table}, immediately before the next label. | |
4736 | This secondary jump table is preceded by a short-jump to the | |
47342e8f RP |
4737 | first byte after the secondary table. This short-jump prevents the flow |
4738 | of control from accidentally falling into the new table. Inside the | |
05a0e43b RP |
4739 | table is a long-jump to @code{sym2}. The original @samp{.word} |
4740 | contains @code{sym1} minus the address of the long-jump to | |
d0281557 | 4741 | @code{sym2}. |
47342e8f RP |
4742 | |
4743 | If there were several occurrences of @samp{.word sym1-sym2} before the | |
05a0e43b | 4744 | secondary jump table, all of them are adjusted. If there was a |
47342e8f | 4745 | @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a |
05a0e43b RP |
4746 | long-jump to @code{sym4} is included in the secondary jump table, |
4747 | and the @code{.word} directives are adjusted to contain @code{sym3} | |
47342e8f | 4748 | minus the address of the long-jump to @code{sym4}; and so on, for as many |
d0281557 | 4749 | entries in the original jump table as necessary. |
09352a5d | 4750 | |
f009d0ab RP |
4751 | @ifset INTERNALS |
4752 | @emph{This feature may be disabled by compiling @code{@value{AS}} with the | |
47342e8f RP |
4753 | @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse |
4754 | assembly language programmers. | |
f009d0ab RP |
4755 | @end ifset |
4756 | @end ifset | |
4757 | @c end DIFF-TBL-KLUGE | |
93b45514 | 4758 | |
242d9c06 | 4759 | @node Deprecated |
93b45514 | 4760 | @section Deprecated Directives |
66b818fb RP |
4761 | |
4762 | @cindex deprecated directives | |
4763 | @cindex obsolescent directives | |
93b45514 RP |
4764 | One day these directives won't work. |
4765 | They are included for compatibility with older assemblers. | |
4766 | @table @t | |
4767 | @item .abort | |
93b45514 RP |
4768 | @item .line |
4769 | @end table | |
4770 | ||
f009d0ab RP |
4771 | @ifset GENERIC |
4772 | @node Machine Dependencies | |
09352a5d | 4773 | @chapter Machine Dependent Features |
66b818fb RP |
4774 | |
4775 | @cindex machine dependencies | |
4776 | The machine instruction sets are (almost by definition) different on | |
f009d0ab RP |
4777 | each machine where @code{@value{AS}} runs. Floating point representations |
4778 | vary as well, and @code{@value{AS}} often supports a few additional | |
66b818fb RP |
4779 | directives or command-line options for compatibility with other |
4780 | assemblers on a particular platform. Finally, some versions of | |
f009d0ab | 4781 | @code{@value{AS}} support special pseudo-instructions for branch |
66b818fb RP |
4782 | optimization. |
4783 | ||
4784 | This chapter discusses most of these differences, though it does not | |
4785 | include details on any machine's instruction set. For details on that | |
4786 | subject, see the hardware manufacturer's manual. | |
4787 | ||
7a4c8e5c | 4788 | @menu |
910d7df2 C |
4789 | @ifset A29K |
4790 | * AMD29K-Dependent:: AMD 29K Dependent Features | |
4791 | @end ifset | |
99c4053d KR |
4792 | @ifset ARC |
4793 | * ARC-Dependent:: ARC Dependent Features | |
4794 | @end ifset | |
3ffb03b1 DE |
4795 | @ifset ARM |
4796 | * ARM-Dependent:: ARM Dependent Features | |
4797 | @end ifset | |
9a5acea8 ILT |
4798 | @ifset D10V |
4799 | * D10V-Dependent:: D10V Dependent Features | |
4800 | @end ifset | |
c3b27a64 RH |
4801 | @ifset D30V |
4802 | * D30V-Dependent:: D30V Dependent Features | |
4803 | @end ifset | |
f009d0ab | 4804 | @ifset H8/300 |
ba487f3a | 4805 | * H8/300-Dependent:: Hitachi H8/300 Dependent Features |
f009d0ab RP |
4806 | @end ifset |
4807 | @ifset H8/500 | |
4808 | * H8/500-Dependent:: Hitachi H8/500 Dependent Features | |
4809 | @end ifset | |
9dcf8057 | 4810 | @ifset HPPA |
fb5bec49 | 4811 | * HPPA-Dependent:: HPPA Dependent Features |
9dcf8057 | 4812 | @end ifset |
910d7df2 C |
4813 | @ifset I80386 |
4814 | * i386-Dependent:: Intel 80386 Dependent Features | |
f009d0ab | 4815 | @end ifset |
f009d0ab | 4816 | @ifset I960 |
ba487f3a | 4817 | * i960-Dependent:: Intel 80960 Dependent Features |
f009d0ab | 4818 | @end ifset |
ef582182 | 4819 | @c start-sanitize-m32rx |
ee73be40 NC |
4820 | @ifset M32R |
4821 | * M32R-Dependent:: M32R Dependent Features | |
4822 | @end ifset | |
ef582182 | 4823 | @c end-sanitize-m32rx |
f009d0ab | 4824 | @ifset M680X0 |
ba487f3a | 4825 | * M68K-Dependent:: M680x0 Dependent Features |
f009d0ab | 4826 | @end ifset |
910d7df2 C |
4827 | @ifset MIPS |
4828 | * MIPS-Dependent:: MIPS Dependent Features | |
4829 | @end ifset | |
4830 | @ifset SH | |
4831 | * SH-Dependent:: Hitachi SH Dependent Features | |
4832 | @end ifset | |
f009d0ab | 4833 | @ifset SPARC |
ba487f3a | 4834 | * Sparc-Dependent:: SPARC Dependent Features |
f009d0ab | 4835 | @end ifset |
11959ebc ILT |
4836 | @ifset V850 |
4837 | * V850-Dependent:: V850 Dependent Features | |
4838 | @end ifset | |
f009d0ab | 4839 | @ifset Z8000 |
ba487f3a | 4840 | * Z8000-Dependent:: Z8000 Dependent Features |
f009d0ab | 4841 | @end ifset |
910d7df2 C |
4842 | @ifset VAX |
4843 | * Vax-Dependent:: VAX Dependent Features | |
f009d0ab | 4844 | @end ifset |
7a4c8e5c RP |
4845 | @end menu |
4846 | ||
9dcf8057 | 4847 | @lowersections |
f009d0ab RP |
4848 | @end ifset |
4849 | ||
4850 | @c The following major nodes are *sections* in the GENERIC version, *chapters* | |
9dcf8057 | 4851 | @c in single-cpu versions. This is mainly achieved by @lowersections. There is a |
f009d0ab RP |
4852 | @c peculiarity: to preserve cross-references, there must be a node called |
4853 | @c "Machine Dependencies". Hence the conditional nodenames in each | |
4854 | @c major node below. Node defaulting in makeinfo requires adjacency of | |
4855 | @c node and sectioning commands; hence the repetition of @chapter BLAH | |
4856 | @c in both conditional blocks. | |
99c4053d | 4857 | |
99c4053d KR |
4858 | @ifset ARC |
4859 | @ifset GENERIC | |
4860 | @page | |
4861 | @node ARC-Dependent | |
4862 | @chapter ARC Dependent Features | |
4863 | @end ifset | |
4864 | @ifclear GENERIC | |
4865 | @node Machine Dependencies | |
4866 | @chapter ARC Dependent Features | |
4867 | @end ifclear | |
4868 | ||
4869 | @cindex ARC support | |
4870 | @menu | |
4871 | * ARC-Opts:: Options | |
4872 | * ARC-Float:: Floating Point | |
4873 | * ARC-Directives:: Sparc Machine Directives | |
4874 | @end menu | |
4875 | ||
4876 | @node ARC-Opts | |
4877 | @section Options | |
4878 | ||
4879 | @cindex options for ARC | |
4880 | @cindex ARC options | |
4881 | @cindex architectures, ARC | |
4882 | @cindex ARC architectures | |
4883 | The ARC chip family includes several successive levels (or other | |
4884 | variants) of chip, using the same core instruction set, but including | |
4885 | a few additional instructions at each level. | |
4886 | ||
4887 | By default, @code{@value{AS}} assumes the core instruction set (ARC | |
3ffb03b1 DE |
4888 | base). The @code{.cpu} pseudo-op is intended to be used to select |
4889 | the variant. | |
99c4053d KR |
4890 | |
4891 | @table @code | |
4892 | @cindex @code{-mbig-endian} option (ARC) | |
4893 | @cindex @code{-mlittle-endian} option (ARC) | |
4894 | @cindex ARC big-endian output | |
4895 | @cindex ARC little-endian output | |
4896 | @cindex big-endian output, ARC | |
4897 | @cindex little-endian output, ARC | |
4898 | @item -mbig-endian | |
4899 | @itemx -mlittle-endian | |
4900 | Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or | |
4901 | little-endian output at run time (unlike most other @sc{gnu} development | |
4902 | tools, which must be configured for one or the other). Use | |
4903 | @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian} | |
4904 | for little-endian. | |
4905 | @end table | |
4906 | ||
4907 | @node ARC-Float | |
4908 | @section Floating Point | |
4909 | ||
4910 | @cindex floating point, ARC (@sc{ieee}) | |
4911 | @cindex ARC floating point (@sc{ieee}) | |
4912 | The ARC cpu family currently does not have hardware floating point | |
4913 | support. Software floating point support is provided by @code{GCC} | |
4914 | and uses @sc{ieee} floating-point numbers. | |
4915 | ||
4916 | @node ARC-Directives | |
4917 | @section ARC Machine Directives | |
4918 | ||
4919 | @cindex ARC machine directives | |
4920 | @cindex machine directives, ARC | |
4921 | The ARC version of @code{@value{AS}} supports the following additional | |
4922 | machine directives: | |
4923 | ||
4924 | @table @code | |
4925 | @item .cpu | |
4926 | @cindex @code{cpu} directive, SPARC | |
3ffb03b1 DE |
4927 | This must be followed by the desired cpu. |
4928 | The ARC is intended to be customizable, @code{.cpu} is used to | |
4929 | select the desired variant [though currently there are none]. | |
99c4053d KR |
4930 | |
4931 | @end table | |
4932 | ||
4933 | @end ifset | |
99c4053d | 4934 | |
f009d0ab | 4935 | @ifset A29K |
79e15b8a | 4936 | @include c-a29k.texi |
f009d0ab | 4937 | @end ifset |
b50e59fe | 4938 | |
3ffb03b1 DE |
4939 | @ifset ARM |
4940 | @include c-arm.texi | |
4941 | @end ifset | |
4942 | ||
f009d0ab RP |
4943 | @ifset Hitachi-all |
4944 | @ifclear GENERIC | |
4945 | @node Machine Dependencies | |
4946 | @chapter Machine Dependent Features | |
4947 | ||
4948 | The machine instruction sets are different on each Hitachi chip family, | |
4949 | and there are also some syntax differences among the families. This | |
4950 | chapter describes the specific @code{@value{AS}} features for each | |
4951 | family. | |
4952 | ||
4953 | @menu | |
4954 | * H8/300-Dependent:: Hitachi H8/300 Dependent Features | |
4955 | * H8/500-Dependent:: Hitachi H8/500 Dependent Features | |
f009d0ab | 4956 | * SH-Dependent:: Hitachi SH Dependent Features |
f009d0ab | 4957 | @end menu |
9dcf8057 | 4958 | @lowersections |
f009d0ab RP |
4959 | @end ifclear |
4960 | @end ifset | |
4961 | ||
9a5acea8 ILT |
4962 | @ifset D10V |
4963 | @include c-d10v.texi | |
4964 | @end ifset | |
9a5acea8 | 4965 | |
c3b27a64 RH |
4966 | @ifset D30V |
4967 | @include c-d30v.texi | |
4968 | @end ifset | |
c3b27a64 | 4969 | |
f009d0ab | 4970 | @ifset H8/300 |
79e15b8a | 4971 | @include c-h8300.texi |
f009d0ab | 4972 | @end ifset |
24b1493d | 4973 | |
79e15b8a ILT |
4974 | @ifset H8/500 |
4975 | @include c-h8500.texi | |
fb5bec49 | 4976 | @end ifset |
66b818fb | 4977 | |
79e15b8a ILT |
4978 | @ifset HPPA |
4979 | @include c-hppa.texi | |
4980 | @end ifset | |
66b818fb | 4981 | |
910d7df2 C |
4982 | @ifset I80386 |
4983 | @include c-i386.texi | |
79e15b8a | 4984 | @end ifset |
66b818fb | 4985 | |
79e15b8a ILT |
4986 | @ifset I960 |
4987 | @include c-i960.texi | |
f009d0ab RP |
4988 | @end ifset |
4989 | ||
ef582182 | 4990 | @c start-sanitize-m32rx |
ee73be40 NC |
4991 | @ifset M32R |
4992 | @include c-m32r.texi | |
4993 | @end ifset | |
ef582182 | 4994 | @c end-sanitize-m32rx |
ee73be40 | 4995 | |
79e15b8a ILT |
4996 | @ifset M680X0 |
4997 | @include c-m68k.texi | |
4998 | @end ifset | |
f009d0ab | 4999 | |
910d7df2 C |
5000 | @ifset MIPS |
5001 | @include c-mips.texi | |
5002 | @end ifset | |
5003 | ||
71dd3c40 ILT |
5004 | @ifset NS32K |
5005 | @include c-ns32k.texi | |
5006 | @end ifset | |
f009d0ab | 5007 | |
910d7df2 C |
5008 | @ifset SH |
5009 | @include c-sh.texi | |
79e15b8a | 5010 | @end ifset |
f009d0ab | 5011 | |
910d7df2 C |
5012 | @ifset SPARC |
5013 | @include c-sparc.texi | |
79e15b8a | 5014 | @end ifset |
fb5bec49 | 5015 | |
79e15b8a ILT |
5016 | @ifset Z8000 |
5017 | @include c-z8k.texi | |
5018 | @end ifset | |
34214344 | 5019 | |
910d7df2 C |
5020 | @ifset VAX |
5021 | @include c-vax.texi | |
34214344 KR |
5022 | @end ifset |
5023 | ||
68eaa141 NC |
5024 | @ifset V850 |
5025 | @include c-v850.texi | |
5026 | @end ifset | |
68eaa141 | 5027 | |
f009d0ab RP |
5028 | @ifset GENERIC |
5029 | @c reverse effect of @down at top of generic Machine-Dep chapter | |
9dcf8057 | 5030 | @raisesections |
f009d0ab RP |
5031 | @end ifset |
5032 | ||
9a5acea8 ILT |
5033 | @node Reporting Bugs |
5034 | @chapter Reporting Bugs | |
3ffb03b1 DE |
5035 | @cindex bugs in assembler |
5036 | @cindex reporting bugs in assembler | |
9a5acea8 ILT |
5037 | |
5038 | Your bug reports play an essential role in making @code{@value{AS}} reliable. | |
5039 | ||
5040 | Reporting a bug may help you by bringing a solution to your problem, or it may | |
5041 | not. But in any case the principal function of a bug report is to help the | |
5042 | entire community by making the next version of @code{@value{AS}} work better. | |
5043 | Bug reports are your contribution to the maintenance of @code{@value{AS}}. | |
5044 | ||
5045 | In order for a bug report to serve its purpose, you must include the | |
5046 | information that enables us to fix the bug. | |
5047 | ||
5048 | @menu | |
5049 | * Bug Criteria:: Have you found a bug? | |
5050 | * Bug Reporting:: How to report bugs | |
5051 | @end menu | |
5052 | ||
5053 | @node Bug Criteria | |
5054 | @section Have you found a bug? | |
5055 | @cindex bug criteria | |
5056 | ||
5057 | If you are not sure whether you have found a bug, here are some guidelines: | |
5058 | ||
5059 | @itemize @bullet | |
5060 | @cindex fatal signal | |
5061 | @cindex assembler crash | |
5062 | @cindex crash of assembler | |
5063 | @item | |
5064 | If the assembler gets a fatal signal, for any input whatever, that is a | |
5065 | @code{@value{AS}} bug. Reliable assemblers never crash. | |
5066 | ||
5067 | @cindex error on valid input | |
5068 | @item | |
5069 | If @code{@value{AS}} produces an error message for valid input, that is a bug. | |
5070 | ||
5071 | @cindex invalid input | |
5072 | @item | |
5073 | If @code{@value{AS}} does not produce an error message for invalid input, that | |
5074 | is a bug. However, you should note that your idea of ``invalid input'' might | |
5075 | be our idea of ``an extension'' or ``support for traditional practice''. | |
5076 | ||
5077 | @item | |
5078 | If you are an experienced user of assemblers, your suggestions for improvement | |
5079 | of @code{@value{AS}} are welcome in any case. | |
5080 | @end itemize | |
5081 | ||
5082 | @node Bug Reporting | |
5083 | @section How to report bugs | |
5084 | @cindex bug reports | |
3ffb03b1 | 5085 | @cindex assembler bugs, reporting |
9a5acea8 ILT |
5086 | |
5087 | A number of companies and individuals offer support for @sc{gnu} products. If | |
5088 | you obtained @code{@value{AS}} from a support organization, we recommend you | |
5089 | contact that organization first. | |
5090 | ||
5091 | You can find contact information for many support companies and | |
5092 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
5093 | distribution. | |
5094 | ||
5095 | In any event, we also recommend that you send bug reports for @code{@value{AS}} | |
43448efe | 5096 | to @samp{bug-gnu-utils@@gnu.org}. |
9a5acea8 ILT |
5097 | |
5098 | The fundamental principle of reporting bugs usefully is this: | |
5099 | @strong{report all the facts}. If you are not sure whether to state a | |
5100 | fact or leave it out, state it! | |
5101 | ||
5102 | Often people omit facts because they think they know what causes the problem | |
5103 | and assume that some details do not matter. Thus, you might assume that the | |
5104 | name of a symbol you use in an example does not matter. Well, probably it does | |
5105 | not, but one cannot be sure. Perhaps the bug is a stray memory reference which | |
5106 | happens to fetch from the location where that name is stored in memory; | |
5107 | perhaps, if the name were different, the contents of that location would fool | |
5108 | the assembler into doing the right thing despite the bug. Play it safe and | |
5109 | give a specific, complete example. That is the easiest thing for you to do, | |
5110 | and the most helpful. | |
5111 | ||
5112 | Keep in mind that the purpose of a bug report is to enable us to fix the bug if | |
5113 | it is new to us. Therefore, always write your bug reports on the assumption | |
5114 | that the bug has not been reported previously. | |
5115 | ||
5116 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
5117 | bell?'' Those bug reports are useless, and we urge everyone to | |
5118 | @emph{refuse to respond to them} except to chide the sender to report | |
5119 | bugs properly. | |
5120 | ||
5121 | To enable us to fix the bug, you should include all these things: | |
5122 | ||
5123 | @itemize @bullet | |
5124 | @item | |
5125 | The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start | |
868c3513 | 5126 | it with the @samp{--version} argument. |
9a5acea8 ILT |
5127 | |
5128 | Without this, we will not know whether there is any point in looking for | |
5129 | the bug in the current version of @code{@value{AS}}. | |
5130 | ||
5131 | @item | |
5132 | Any patches you may have applied to the @code{@value{AS}} source. | |
5133 | ||
5134 | @item | |
5135 | The type of machine you are using, and the operating system name and | |
5136 | version number. | |
5137 | ||
5138 | @item | |
5139 | What compiler (and its version) was used to compile @code{@value{AS}}---e.g. | |
5140 | ``@code{gcc-2.7}''. | |
5141 | ||
5142 | @item | |
5143 | The command arguments you gave the assembler to assemble your example and | |
5144 | observe the bug. To guarantee you will not omit something important, list them | |
5145 | all. A copy of the Makefile (or the output from make) is sufficient. | |
5146 | ||
5147 | If we were to try to guess the arguments, we would probably guess wrong | |
5148 | and then we might not encounter the bug. | |
5149 | ||
5150 | @item | |
5151 | A complete input file that will reproduce the bug. If the bug is observed when | |
5152 | the assembler is invoked via a compiler, send the assembler source, not the | |
5153 | high level language source. Most compilers will produce the assembler source | |
5154 | when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use | |
5155 | the options @samp{-v --save-temps}; this will save the assembler source in a | |
5156 | file with an extension of @file{.s}, and also show you exactly how | |
5157 | @code{@value{AS}} is being run. | |
5158 | ||
5159 | @item | |
5160 | A description of what behavior you observe that you believe is | |
5161 | incorrect. For example, ``It gets a fatal signal.'' | |
5162 | ||
5163 | Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we | |
5164 | will certainly notice it. But if the bug is incorrect output, we might not | |
5165 | notice unless it is glaringly wrong. You might as well not give us a chance to | |
5166 | make a mistake. | |
5167 | ||
5168 | Even if the problem you experience is a fatal signal, you should still say so | |
5169 | explicitly. Suppose something strange is going on, such as, your copy of | |
5170 | @code{@value{AS}} is out of synch, or you have encountered a bug in the C | |
5171 | library on your system. (This has happened!) Your copy might crash and ours | |
5172 | would not. If you told us to expect a crash, then when ours fails to crash, we | |
5173 | would know that the bug was not happening for us. If you had not told us to | |
5174 | expect a crash, then we would not be able to draw any conclusion from our | |
5175 | observations. | |
5176 | ||
5177 | @item | |
5178 | If you wish to suggest changes to the @code{@value{AS}} source, send us context | |
5179 | diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} | |
5180 | option. Always send diffs from the old file to the new file. If you even | |
5181 | discuss something in the @code{@value{AS}} source, refer to it by context, not | |
5182 | by line number. | |
5183 | ||
5184 | The line numbers in our development sources will not match those in your | |
5185 | sources. Your line numbers would convey no useful information to us. | |
5186 | @end itemize | |
5187 | ||
5188 | Here are some things that are not necessary: | |
5189 | ||
5190 | @itemize @bullet | |
5191 | @item | |
5192 | A description of the envelope of the bug. | |
5193 | ||
5194 | Often people who encounter a bug spend a lot of time investigating | |
5195 | which changes to the input file will make the bug go away and which | |
5196 | changes will not affect it. | |
5197 | ||
5198 | This is often time consuming and not very useful, because the way we | |
5199 | will find the bug is by running a single example under the debugger | |
5200 | with breakpoints, not by pure deduction from a series of examples. | |
5201 | We recommend that you save your time for something else. | |
5202 | ||
5203 | Of course, if you can find a simpler example to report @emph{instead} | |
5204 | of the original one, that is a convenience for us. Errors in the | |
5205 | output will be easier to spot, running under the debugger will take | |
5206 | less time, and so on. | |
5207 | ||
5208 | However, simplification is not vital; if you do not want to do this, | |
5209 | report the bug anyway and send us the entire test case you used. | |
5210 | ||
5211 | @item | |
5212 | A patch for the bug. | |
5213 | ||
5214 | A patch for the bug does help us if it is a good one. But do not omit | |
5215 | the necessary information, such as the test case, on the assumption that | |
5216 | a patch is all we need. We might see problems with your patch and decide | |
5217 | to fix the problem another way, or we might not understand it at all. | |
5218 | ||
5219 | Sometimes with a program as complicated as @code{@value{AS}} it is very hard to | |
5220 | construct an example that will make the program follow a certain path through | |
5221 | the code. If you do not send us the example, we will not be able to construct | |
5222 | one, so we will not be able to verify that the bug is fixed. | |
5223 | ||
5224 | And if we cannot understand what bug you are trying to fix, or why your | |
5225 | patch should be an improvement, we will not install it. A test case will | |
5226 | help us to understand. | |
5227 | ||
5228 | @item | |
5229 | A guess about what the bug is or what it depends on. | |
5230 | ||
5231 | Such guesses are usually wrong. Even we cannot guess right about such | |
5232 | things without first using the debugger to find the facts. | |
5233 | @end itemize | |
5234 | ||
9dcf8057 JL |
5235 | @node Acknowledgements |
5236 | @chapter Acknowledgements | |
5237 | ||
05a0e43b RP |
5238 | If you have contributed to @code{@value{AS}} and your name isn't listed here, |
5239 | it is not meant as a slight. We just don't know about it. Send mail to the | |
71dd3c40 ILT |
5240 | maintainer, and we'll correct the situation. Currently |
5241 | @c (January 1994), | |
5242 | the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). | |
9dcf8057 | 5243 | |
79e15b8a ILT |
5244 | Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any |
5245 | more details?} | |
9dcf8057 | 5246 | |
05a0e43b | 5247 | Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug |
9dcf8057 | 5248 | information and the 68k series machines, most of the preprocessing pass, and |
05a0e43b | 5249 | extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. |
9dcf8057 JL |
5250 | |
5251 | K. Richard Pixley maintained GAS for a while, adding various enhancements and | |
5252 | many bug fixes, including merging support for several processors, breaking GAS | |
05a0e43b RP |
5253 | up to handle multiple object file format back ends (including heavy rewrite, |
5254 | testing, an integration of the coff and b.out back ends), adding configuration | |
9dcf8057 | 5255 | including heavy testing and verification of cross assemblers and file splits |
05a0e43b RP |
5256 | and renaming, converted GAS to strictly ANSI C including full prototypes, added |
5257 | support for m680[34]0 and cpu32, did considerable work on i960 including a COFF | |
5258 | port (including considerable amounts of reverse engineering), a SPARC opcode | |
5259 | file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' | |
9dcf8057 JL |
5260 | assertions and made them work, much other reorganization, cleanup, and lint. |
5261 | ||
5262 | Ken Raeburn wrote the high-level BFD interface code to replace most of the code | |
5263 | in format-specific I/O modules. | |
5264 | ||
5265 | The original VMS support was contributed by David L. Kashtan. Eric Youngdale | |
5266 | has done much work with it since. | |
5267 | ||
5268 | The Intel 80386 machine description was written by Eliot Dresselhaus. | |
5269 | ||
5270 | Minh Tran-Le at IntelliCorp contributed some AIX 386 support. | |
5271 | ||
5272 | The Motorola 88k machine description was contributed by Devon Bowen of Buffalo | |
5273 | University and Torbjorn Granlund of the Swedish Institute of Computer Science. | |
5274 | ||
5275 | Keith Knowles at the Open Software Foundation wrote the original MIPS back end | |
05a0e43b RP |
5276 | (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support |
5277 | (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to | |
5278 | support a.out format. | |
9dcf8057 JL |
5279 | |
5280 | Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k, | |
5281 | tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by | |
5282 | Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to | |
5283 | use BFD for some low-level operations, for use with the H8/300 and AMD 29k | |
5284 | targets. | |
5285 | ||
05a0e43b RP |
5286 | John Gilmore built the AMD 29000 support, added @code{.include} support, and |
5287 | simplified the configuration of which versions accept which directives. He | |
9dcf8057 | 5288 | updated the 68k machine description so that Motorola's opcodes always produced |
05a0e43b RP |
5289 | fixed-size instructions (e.g. @code{jsr}), while synthetic instructions |
5290 | remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested | |
9dcf8057 | 5291 | cross-compilation support, and one bug in relaxation that took a week and |
47c7ceb5 | 5292 | required the proverbial one-bit fix. |
9dcf8057 | 5293 | |
05a0e43b | 5294 | Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the |
9dcf8057 | 5295 | 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), |
910d7df2 C |
5296 | added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and |
5297 | PowerPC assembler, and made a few other minor patches. | |
9dcf8057 JL |
5298 | |
5299 | Steve Chamberlain made @code{@value{AS}} able to generate listings. | |
5300 | ||
05a0e43b | 5301 | Hewlett-Packard contributed support for the HP9000/300. |
9dcf8057 | 5302 | |
05a0e43b RP |
5303 | Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) |
5304 | along with a fairly extensive HPPA testsuite (for both SOM and ELF object | |
5305 | formats). This work was supported by both the Center for Software Science at | |
5306 | the University of Utah and Cygnus Support. | |
9dcf8057 JL |
5307 | |
5308 | Support for ELF format files has been worked on by Mark Eichin of Cygnus | |
5309 | Support (original, incomplete implementation for SPARC), Pete Hoogenboom and | |
5310 | Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open | |
5311 | Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, | |
5312 | and some initial 64-bit support). | |
5313 | ||
8a51eeaf TT |
5314 | Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD |
5315 | support for openVMS/Alpha. | |
910d7df2 | 5316 | |
9dcf8057 JL |
5317 | Several engineers at Cygnus Support have also provided many small bug fixes and |
5318 | configuration enhancements. | |
5319 | ||
5320 | Many others have contributed large or small bugfixes and enhancements. If | |
05a0e43b RP |
5321 | you have contributed significant work and are not mentioned on this list, and |
5322 | want to be, let us know. Some of the history has been lost; we are not | |
9dcf8057 JL |
5323 | intentionally leaving anyone out. |
5324 | ||
242d9c06 | 5325 | @node Index |
66b818fb RP |
5326 | @unnumbered Index |
5327 | ||
5328 | @printindex cp | |
5329 | ||
93b45514 RP |
5330 | @contents |
5331 | @bye | |
9dcf8057 JL |
5332 | @c Local Variables: |
5333 | @c fill-column: 79 | |
5334 | @c End: |