Commit | Line | Data |
---|---|---|
66b818fb | 1 | \input texinfo @c -*-Texinfo-*- |
4d32706e | 2 | @c Copyright (c) 1991, 92, 93, 94, 95, 96, 1997 Free Software Foundation, Inc. |
e680d737 RP |
3 | @c UPDATE!! On future updates-- |
4 | @c (1) check for new machine-dep cmdline options in | |
5 | @c md_parse_option definitions in config/tc-*.c | |
6 | @c (2) for platform-specific directives, examine md_pseudo_op | |
7 | @c in config/tc-*.c | |
8 | @c (3) for object-format specific directives, examine obj_pseudo_op | |
9 | @c in config/obj-*.c | |
10 | @c (4) portable directives in potable[] in read.c | |
f009d0ab RP |
11 | @c %**start of header |
12 | @setfilename as.info | |
13 | @c ---config--- | |
14 | @c defaults, config file may override: | |
15 | @set have-stabs | |
16 | @c --- | |
4b9f4409 | 17 | @include asconfig.texi |
f009d0ab RP |
18 | @c --- |
19 | @c common OR combinations of conditions | |
20 | @ifset AOUT | |
21 | @set aout-bout | |
22 | @end ifset | |
3ffb03b1 DE |
23 | @ifset ARM/Thumb |
24 | @set ARM | |
25 | @end ifset | |
f009d0ab RP |
26 | @ifset BOUT |
27 | @set aout-bout | |
28 | @end ifset | |
29 | @ifset H8/300 | |
30 | @set H8 | |
31 | @end ifset | |
32 | @ifset H8/500 | |
33 | @set H8 | |
34 | @end ifset | |
f009d0ab RP |
35 | @ifset SH |
36 | @set H8 | |
37 | @end ifset | |
9dcf8057 JL |
38 | @ifset HPPA |
39 | @set abnormal-separator | |
40 | @end ifset | |
f009d0ab RP |
41 | @c ------------ |
42 | @ifset GENERIC | |
43 | @settitle Using @value{AS} | |
44 | @end ifset | |
45 | @ifclear GENERIC | |
46 | @settitle Using @value{AS} (@value{TARGET}) | |
47 | @end ifclear | |
66b818fb | 48 | @setchapternewpage odd |
66b818fb RP |
49 | @c %**end of header |
50 | ||
fb5bec49 RP |
51 | @c @smallbook |
52 | @c @set SMALL | |
53 | @c WARE! Some of the machine-dependent sections contain tables of machine | |
54 | @c instructions. Except in multi-column format, these tables look silly. | |
55 | @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so | |
56 | @c the multi-col format is faked within @example sections. | |
57 | @c | |
58 | @c Again unfortunately, the natural size that fits on a page, for these tables, | |
59 | @c is different depending on whether or not smallbook is turned on. | |
60 | @c This matters, because of order: text flow switches columns at each page | |
61 | @c break. | |
62 | @c | |
63 | @c The format faked in this source works reasonably well for smallbook, | |
64 | @c not well for the default large-page format. This manual expects that if you | |
65 | @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the | |
66 | @c tables in question. You can turn on one without the other at your | |
67 | @c discretion, of course. | |
68 | @ifinfo | |
69 | @set SMALL | |
70 | @c the insn tables look just as silly in info files regardless of smallbook, | |
71 | @c might as well show 'em anyways. | |
72 | @end ifinfo | |
73 | ||
80381063 RP |
74 | @ifinfo |
75 | @format | |
dd565f85 RP |
76 | START-INFO-DIR-ENTRY |
77 | * As: (as). The GNU assembler. | |
78 | END-INFO-DIR-ENTRY | |
80381063 RP |
79 | @end format |
80 | @end ifinfo | |
81 | ||
66b818fb RP |
82 | @finalout |
83 | @syncodeindex ky cp | |
84 | ||
47342e8f | 85 | @ifinfo |
f009d0ab | 86 | This file documents the GNU Assembler "@value{AS}". |
47342e8f | 87 | |
4d32706e | 88 | Copyright (C) 1991, 92, 93, 94, 95, 96, 1997 Free Software Foundation, Inc. |
47342e8f RP |
89 | |
90 | Permission is granted to make and distribute verbatim copies of | |
91 | this manual provided the copyright notice and this permission notice | |
92 | are preserved on all copies. | |
93 | ||
94 | @ignore | |
95 | Permission is granted to process this file through Tex and print the | |
96 | results, provided the printed document carries copying permission | |
97 | notice identical to this one except for the removal of this paragraph | |
98 | (this paragraph not being relevant to the printed manual). | |
99 | ||
100 | @end ignore | |
81fcb3ff RP |
101 | Permission is granted to copy and distribute modified versions of this manual |
102 | under the conditions for verbatim copying, provided that the entire resulting | |
103 | derived work is distributed under the terms of a permission notice identical to | |
104 | this one. | |
47342e8f RP |
105 | |
106 | Permission is granted to copy and distribute translations of this manual | |
81fcb3ff | 107 | into another language, under the above conditions for modified versions. |
47342e8f | 108 | @end ifinfo |
66b818fb | 109 | |
93b45514 | 110 | @titlepage |
f009d0ab | 111 | @title Using @value{AS} |
71dd3c40 | 112 | @subtitle The @sc{gnu} Assembler |
f009d0ab RP |
113 | @ifclear GENERIC |
114 | @subtitle for the @value{TARGET} family | |
115 | @end ifclear | |
93b45514 | 116 | @sp 1 |
e680d737 | 117 | @subtitle January 1994 |
0b5b143a | 118 | @sp 1 |
93b45514 RP |
119 | @sp 13 |
120 | The Free Software Foundation Inc. thanks The Nice Computer | |
121 | Company of Australia for loaning Dean Elsner to write the | |
71dd3c40 | 122 | first (Vax) version of @code{as} for Project @sc{gnu}. |
93b45514 RP |
123 | The proprietors, management and staff of TNCCA thank FSF for |
124 | distracting the boss while they got some work | |
125 | done. | |
126 | @sp 3 | |
7d7ecbdd | 127 | @author Dean Elsner, Jay Fenlason & friends |
47342e8f RP |
128 | @page |
129 | @tex | |
47342e8f | 130 | {\parskip=0pt |
f009d0ab | 131 | \hfill {\it Using {\tt @value{AS}}}\par |
71dd3c40 | 132 | \hfill Edited by Cygnus Support\par |
47342e8f | 133 | } |
b50e59fe RP |
134 | %"boxit" macro for figures: |
135 | %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3) | |
136 | \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt | |
137 | \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil | |
138 | #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline | |
139 | \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box | |
47342e8f | 140 | @end tex |
93b45514 | 141 | |
47342e8f | 142 | @vskip 0pt plus 1filll |
4d32706e | 143 | Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 1997 Free Software Foundation, Inc. |
93b45514 RP |
144 | |
145 | Permission is granted to make and distribute verbatim copies of | |
146 | this manual provided the copyright notice and this permission notice | |
147 | are preserved on all copies. | |
148 | ||
81fcb3ff RP |
149 | Permission is granted to copy and distribute modified versions of this manual |
150 | under the conditions for verbatim copying, provided that the entire resulting | |
151 | derived work is distributed under the terms of a permission notice identical to | |
152 | this one. | |
93b45514 RP |
153 | |
154 | Permission is granted to copy and distribute translations of this manual | |
81fcb3ff | 155 | into another language, under the above conditions for modified versions. |
93b45514 | 156 | @end titlepage |
f009d0ab | 157 | |
d0281557 | 158 | @ifinfo |
242d9c06 | 159 | @node Top |
f009d0ab | 160 | @top Using @value{AS} |
242d9c06 | 161 | |
8babef85 | 162 | This file is a user guide to the @sc{gnu} assembler @code{@value{AS}}. |
f009d0ab RP |
163 | @ifclear GENERIC |
164 | This version of the file describes @code{@value{AS}} configured to generate | |
165 | code for @value{TARGET} architectures. | |
166 | @end ifclear | |
7a4c8e5c | 167 | @menu |
ba487f3a RP |
168 | * Overview:: Overview |
169 | * Invoking:: Command-Line Options | |
170 | * Syntax:: Syntax | |
171 | * Sections:: Sections and Relocation | |
172 | * Symbols:: Symbols | |
173 | * Expressions:: Expressions | |
174 | * Pseudo Ops:: Assembler Directives | |
f009d0ab | 175 | * Machine Dependencies:: Machine Dependent Features |
9a5acea8 | 176 | * Reporting Bugs:: Reporting Bugs |
9dcf8057 | 177 | * Acknowledgements:: Who Did What |
66b818fb | 178 | * Index:: Index |
7a4c8e5c | 179 | @end menu |
242d9c06 | 180 | @end ifinfo |
7a4c8e5c | 181 | |
242d9c06 | 182 | @node Overview |
b50e59fe | 183 | @chapter Overview |
d0281557 | 184 | @iftex |
8babef85 | 185 | This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}. |
f009d0ab RP |
186 | @ifclear GENERIC |
187 | This version of the manual describes @code{@value{AS}} configured to generate | |
188 | code for @value{TARGET} architectures. | |
189 | @end ifclear | |
d0281557 | 190 | @end iftex |
b50e59fe | 191 | |
66b818fb RP |
192 | @cindex invocation summary |
193 | @cindex option summary | |
194 | @cindex summary of options | |
f009d0ab | 195 | Here is a brief summary of how to invoke @code{@value{AS}}. For details, |
7a4c8e5c | 196 | @pxref{Invoking,,Comand-Line Options}. |
b50e59fe | 197 | |
7d7ecbdd | 198 | @c We don't use deffn and friends for the following because they seem |
b50e59fe | 199 | @c to be limited to one line for the header. |
d0281557 | 200 | @smallexample |
35cfacf0 | 201 | @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ] |
cd924033 | 202 | [ -f ] [ --gstabs ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ] |
71dd3c40 ILT |
203 | [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ] [ -version ] |
204 | [ --version ] [ -W ] [ -w ] [ -x ] [ -Z ] | |
f009d0ab | 205 | @ifset A29K |
2d8e0f62 | 206 | @c am29k has no machine-dependent assembler options |
f009d0ab | 207 | @end ifset |
99c4053d KR |
208 | @ifset ARC |
209 | [ -mbig-endian | -mlittle-endian ] | |
210 | @end ifset | |
3ffb03b1 DE |
211 | @ifset ARM |
212 | [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]7[t][[d]m[i]] ] | |
213 | [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t ] | |
214 | [ -mthumb | -mall ] | |
215 | [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ] | |
216 | [ -EB | -EL ] | |
217 | [ -mapcs-32 | -mapcs-26 ] | |
218 | @end ifset | |
9a5acea8 ILT |
219 | @ifset D10V |
220 | [ -O ] | |
221 | @end ifset | |
9a5acea8 | 222 | |
f009d0ab RP |
223 | @ifset H8 |
224 | @c Hitachi family chips have no machine-dependent assembler options | |
225 | @end ifset | |
9dcf8057 JL |
226 | @ifset HPPA |
227 | @c HPPA has no machine-dependent assembler options (yet). | |
228 | @end ifset | |
f009d0ab | 229 | @ifset SPARC |
71dd3c40 | 230 | @c The order here is important. See c-sparc.texi. |
945229ab DE |
231 | [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
232 | -Av8plus | -Av8plusa | -Av9 | -Av9a ] | |
ee73be40 | 233 | [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ] |
f009d0ab RP |
234 | @end ifset |
235 | @ifset Z8000 | |
2d8e0f62 | 236 | @c Z8000 has no machine-dependent assembler options |
f009d0ab RP |
237 | @end ifset |
238 | @ifset I960 | |
9ebc250f | 239 | @c see md_parse_option in tc-i960.c |
81fcb3ff | 240 | [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ] |
b3b2623c | 241 | [ -b ] [ -no-relax ] |
f009d0ab | 242 | @end ifset |
d745e6d9 | 243 | @c start-sanitize-m32rx |
ee73be40 NC |
244 | @ifset M32R |
245 | [ --m32rx ] | |
246 | @end ifset | |
d745e6d9 | 247 | @c start-sanitize-m32rx |
f009d0ab | 248 | @ifset M680X0 |
81fcb3ff | 249 | [ -l ] [ -m68000 | -m68010 | -m68020 | ... ] |
34214344 KR |
250 | @end ifset |
251 | @ifset MIPS | |
b3b2623c KR |
252 | [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ] |
253 | [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -m4650 ] [ -no-m4650 ] | |
dd565f85 | 254 | [ --trap ] [ --break ] |
ba5ceb30 | 255 | [ --emulation=@var{name} ] |
f009d0ab | 256 | @end ifset |
81fcb3ff | 257 | [ -- | @var{files} @dots{} ] |
d0281557 | 258 | @end smallexample |
47342e8f RP |
259 | |
260 | @table @code | |
68eaa141 | 261 | @item -a[cdhlmns] |
05a0e43b RP |
262 | Turn on listings, in any of a variety of ways: |
263 | ||
264 | @table @code | |
68eaa141 NC |
265 | @item -ac |
266 | omit false conditionals | |
267 | ||
05a0e43b | 268 | @item -ad |
b3b2623c | 269 | omit debugging directives |
05a0e43b RP |
270 | |
271 | @item -ah | |
272 | include high-level source | |
273 | ||
274 | @item -al | |
b3b2623c | 275 | include assembly |
05a0e43b | 276 | |
68eaa141 NC |
277 | @item -am |
278 | include macro expansions | |
279 | ||
05a0e43b | 280 | @item -an |
b3b2623c | 281 | omit forms processing |
05a0e43b RP |
282 | |
283 | @item -as | |
b3b2623c | 284 | include symbols |
85a961c6 ILT |
285 | |
286 | @item =file | |
287 | set the name of the listing file | |
05a0e43b RP |
288 | @end table |
289 | ||
290 | You may combine these options; for example, use @samp{-aln} for assembly | |
85a961c6 | 291 | listing without forms processing. The @samp{=file} option, if used, must be |
68eaa141 | 292 | the last one. By itself, @samp{-a} defaults to @samp{-ahls}. |
b50e59fe RP |
293 | |
294 | @item -D | |
b3b2623c KR |
295 | Ignored. This option is accepted for script compatibility with calls to |
296 | other assemblers. | |
b50e59fe | 297 | |
71dd3c40 ILT |
298 | @item --defsym @var{sym}=@var{value} |
299 | Define the symbol @var{sym} to be @var{value} before assembling the input file. | |
300 | @var{value} must be an integer constant. As in C, a leading @samp{0x} | |
301 | indicates a hexadecimal value, and a leading @samp{0} indicates an octal value. | |
302 | ||
47342e8f | 303 | @item -f |
9dcf8057 | 304 | ``fast''---skip whitespace and comment preprocessing (assume source is |
b3b2623c | 305 | compiler output). |
47342e8f | 306 | |
cd924033 ILT |
307 | @item --gstabs |
308 | Generate stabs debugging information for each assembler line. This | |
309 | may help debugging assembler code, if the debugger can handle it. | |
310 | ||
b3b2623c KR |
311 | @item --help |
312 | Print a summary of the command line options and exit. | |
313 | ||
314 | @item -I @var{dir} | |
315 | Add directory @var{dir} to the search list for @code{.include} directives. | |
316 | ||
317 | @item -J | |
318 | Don't warn about signed overflow. | |
b50e59fe | 319 | |
80381063 | 320 | @item -K |
f009d0ab RP |
321 | @ifclear DIFF-TBL-KLUGE |
322 | This option is accepted but has no effect on the @value{TARGET} family. | |
323 | @end ifclear | |
324 | @ifset DIFF-TBL-KLUGE | |
0b5b143a | 325 | Issue warnings when difference tables altered for long displacements. |
f009d0ab | 326 | @end ifset |
47342e8f RP |
327 | |
328 | @item -L | |
b3b2623c | 329 | Keep (in the symbol table) local symbols, starting with @samp{L}. |
47342e8f RP |
330 | |
331 | @item -o @var{objfile} | |
b3b2623c | 332 | Name the object-file output from @code{@value{AS}} @var{objfile}. |
47342e8f RP |
333 | |
334 | @item -R | |
b3b2623c | 335 | Fold the data section into the text section. |
47342e8f | 336 | |
62e59d28 | 337 | @item --statistics |
b3b2623c | 338 | Print the maximum space (in bytes) and total time (in seconds) used by |
62e59d28 RP |
339 | assembly. |
340 | ||
7d7ecbdd | 341 | @item -v |
b3b2623c KR |
342 | @itemx -version |
343 | Print the @code{as} version. | |
344 | ||
345 | @item --version | |
346 | Print the @code{as} version and exit. | |
7d7ecbdd | 347 | |
47342e8f | 348 | @item -W |
b3b2623c KR |
349 | Suppress warning messages. |
350 | ||
351 | @item -w | |
352 | Ignored. | |
353 | ||
354 | @item -x | |
355 | Ignored. | |
47342e8f | 356 | |
62e59d28 | 357 | @item -Z |
b3b2623c | 358 | Generate an object file even after errors. |
62e59d28 | 359 | |
9ebc250f KR |
360 | @item -- | @var{files} @dots{} |
361 | Standard input, or source files to assemble. | |
9ebc250f KR |
362 | |
363 | @end table | |
364 | ||
99c4053d KR |
365 | @ifset ARC |
366 | The following options are available when @value{AS} is configured for | |
367 | an ARC processor. | |
368 | ||
369 | @table @code | |
370 | ||
371 | @cindex ARC endianness | |
372 | @cindex endianness, ARC | |
373 | @cindex big endian output, ARC | |
374 | @item -mbig-endian | |
375 | Generate ``big endian'' format output. | |
376 | ||
377 | @cindex little endian output, ARC | |
378 | @item -mlittle-endian | |
379 | Generate ``little endian'' format output. | |
380 | ||
381 | @end table | |
382 | @end ifset | |
383 | ||
3ffb03b1 DE |
384 | @ifset ARM |
385 | The following options are available when @value{AS} is configured for the ARM | |
386 | processor family. | |
387 | ||
388 | @table @code | |
389 | @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 | |
390 | Specify which variant of the ARM architecture is the target. | |
391 | @item -mthumb | -mall | |
392 | Enable or disable Thumb only instruction decoding. | |
393 | @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu | |
394 | Select which Floating Point architcture is the target. | |
395 | @item -mapcs-32 | -mapcs-26 | |
396 | Select which procedure calling convention is in use. | |
397 | @item -EB | -EL | |
398 | Select either big-endian (-EB) or little-endian (-EL) output. | |
399 | @end table | |
400 | @end ifset | |
401 | ||
9a5acea8 ILT |
402 | @ifset D10V |
403 | The following options are available when @value{AS} is configured for | |
404 | a D10V processor. | |
405 | @table @code | |
406 | @cindex D10V optimization | |
407 | @cindex optimization, D10V | |
408 | @item -O | |
409 | Optimize output by parallelizing instructions. | |
410 | @end table | |
411 | @end ifset | |
9a5acea8 | 412 | |
f009d0ab RP |
413 | @ifset I960 |
414 | The following options are available when @value{AS} is configured for the | |
9ebc250f KR |
415 | Intel 80960 processor. |
416 | ||
417 | @table @code | |
d0281557 RP |
418 | @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC |
419 | Specify which variant of the 960 architecture is the target. | |
420 | ||
421 | @item -b | |
422 | Add code to collect statistics about branches taken. | |
423 | ||
b3b2623c | 424 | @item -no-relax |
66b818fb | 425 | Do not alter compare-and-branch instructions for long displacements; |
d0281557 | 426 | error if necessary. |
9ebc250f KR |
427 | |
428 | @end table | |
f009d0ab | 429 | @end ifset |
d0281557 | 430 | |
d745e6d9 | 431 | @c start-sanitize-m32rx |
ee73be40 NC |
432 | @ifset M32R |
433 | The following options are available when @value{AS} is configured for the | |
434 | Mitsubishi M32R series. | |
435 | ||
436 | @table @code | |
437 | ||
438 | @item --m32rx | |
439 | Specify which processor in the M32R family is the target. The default | |
440 | is normally the M32R, but this option changes it to the M32RX. | |
441 | ||
442 | @end table | |
443 | @end ifset | |
d745e6d9 | 444 | @c end-sanitize-m32rx |
ee73be40 | 445 | |
f009d0ab RP |
446 | @ifset M680X0 |
447 | The following options are available when @value{AS} is configured for the | |
9ebc250f KR |
448 | Motorola 68000 series. |
449 | ||
450 | @table @code | |
451 | ||
09352a5d | 452 | @item -l |
9ebc250f | 453 | Shorten references to undefined symbols, to one word instead of two. |
09352a5d | 454 | |
910d7df2 C |
455 | @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060 |
456 | @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200 | |
9ebc250f KR |
457 | Specify what processor in the 68000 family is the target. The default |
458 | is normally the 68020, but this can be changed at configuration time. | |
459 | ||
460 | @item -m68881 | -m68882 | -mno-68881 | -mno-68882 | |
461 | The target machine does (or does not) have a floating-point coprocessor. | |
462 | The default is to assume a coprocessor for 68020, 68030, and cpu32. Although | |
463 | the basic 68000 is not compatible with the 68881, a combination of the | |
464 | two can be specified, since it's possible to do emulation of the | |
465 | coprocessor instructions with the main processor. | |
466 | ||
467 | @item -m68851 | -mno-68851 | |
468 | The target machine does (or does not) have a memory-management | |
469 | unit coprocessor. The default is to assume an MMU for 68020 and up. | |
47342e8f | 470 | |
47342e8f | 471 | @end table |
f009d0ab RP |
472 | @end ifset |
473 | ||
474 | @ifset SPARC | |
475 | The following options are available when @code{@value{AS}} is configured | |
476 | for the SPARC architecture: | |
477 | ||
478 | @table @code | |
945229ab DE |
479 | @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite |
480 | @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a | |
f009d0ab RP |
481 | Explicitly select a variant of the SPARC architecture. |
482 | ||
945229ab DE |
483 | @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment. |
484 | @samp{-Av9} and @samp{-Av9a} select a 64 bit environment. | |
485 | ||
486 | @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with | |
487 | UltraSPARC extensions. | |
488 | ||
71dd3c40 ILT |
489 | @item -xarch=v8plus | -xarch=v8plusa |
490 | For compatibility with the Solaris v9 assembler. These options are | |
945229ab | 491 | equivalent to -Av8plus and -Av8plusa, respectively. |
71dd3c40 | 492 | |
f009d0ab RP |
493 | @item -bump |
494 | Warn when the assembler switches to another architecture. | |
495 | @end table | |
496 | @end ifset | |
47342e8f | 497 | |
34214344 KR |
498 | @ifset MIPS |
499 | The following options are available when @value{AS} is configured for | |
dd565f85 | 500 | a MIPS processor. |
34214344 KR |
501 | |
502 | @table @code | |
34214344 | 503 | @item -G @var{num} |
05a0e43b | 504 | This option sets the largest size of an object that can be referenced |
dd565f85 RP |
505 | implicitly with the @code{gp} register. It is only accepted for targets that |
506 | use ECOFF format, such as a DECstation running Ultrix. The default value is 8. | |
34214344 | 507 | |
05a0e43b RP |
508 | @cindex MIPS endianness |
509 | @cindex endianness, MIPS | |
05a0e43b | 510 | @cindex big endian output, MIPS |
dd565f85 | 511 | @item -EB |
05a0e43b RP |
512 | Generate ``big endian'' format output. |
513 | ||
05a0e43b | 514 | @cindex little endian output, MIPS |
dd565f85 | 515 | @item -EL |
05a0e43b | 516 | Generate ``little endian'' format output. |
34214344 | 517 | |
1051c97f ILT |
518 | @cindex MIPS ISA |
519 | @item -mips1 | |
dd565f85 RP |
520 | @itemx -mips2 |
521 | @itemx -mips3 | |
522 | Generate code for a particular MIPS Instruction Set Architecture level. | |
523 | @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors, | |
524 | @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000} | |
525 | processor. | |
1051c97f | 526 | |
b3b2623c KR |
527 | @item -m4650 |
528 | @item -no-m4650 | |
529 | Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept | |
530 | the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop} | |
531 | instructions around accesses to the @samp{HI} and @samp{LO} registers. | |
532 | @samp{-no-m4650} turns off this option. | |
533 | ||
534 | @item -mcpu=@var{CPU} | |
535 | Generate code for a particular MIPS cpu. This has little effect on the | |
536 | assembler, but it is passed by @code{@value{GCC}}. | |
537 | ||
ba5ceb30 KR |
538 | @cindex emulation |
539 | @item --emulation=@var{name} | |
3ffb03b1 | 540 | This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured |
ba5ceb30 KR |
541 | for some other target, in all respects, including output format (choosing |
542 | between ELF and ECOFF only), handling of pseudo-opcodes which may generate | |
543 | debugging information or store symbol table information, and default | |
544 | endianness. The available configuration names are: @samp{mipsecoff}, | |
545 | @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf}, | |
546 | @samp{mipsbelf}. The first two do not alter the default endianness from that | |
547 | of the primary target for which the assembler was configured; the others change | |
548 | the default to little- or big-endian as indicated by the @samp{b} or @samp{l} | |
549 | in the name. Using @samp{-EB} or @samp{-EL} will override the endianness | |
550 | selection in any case. | |
551 | ||
552 | This option is currently supported only when the primary target | |
553 | @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target. | |
554 | Furthermore, the primary target or others specified with | |
555 | @samp{--enable-targets=@dots{}} at configuration time must include support for | |
556 | the other format, if both are to be available. For example, the Irix 5 | |
557 | configuration includes support for both. | |
558 | ||
559 | Eventually, this option will support more configurations, with more | |
560 | fine-grained control over the assembler's behavior, and will be supported for | |
561 | more processors. | |
562 | ||
05a0e43b | 563 | @item -nocpp |
dd565f85 RP |
564 | @code{@value{AS}} ignores this option. It is accepted for compatibility with |
565 | the native tools. | |
566 | ||
71dd3c40 | 567 | @need 900 |
dd565f85 RP |
568 | @item --trap |
569 | @itemx --no-trap | |
570 | @itemx --break | |
571 | @itemx --no-break | |
572 | Control how to deal with multiplication overflow and division by zero. | |
573 | @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception | |
574 | (and only work for Instruction Set Architecture level 2 and higher); | |
575 | @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a | |
576 | break exception. | |
34214344 KR |
577 | @end table |
578 | @end ifset | |
579 | ||
7a4c8e5c | 580 | @menu |
ba487f3a | 581 | * Manual:: Structure of this Manual |
3ffb03b1 | 582 | * GNU Assembler:: The GNU Assembler |
ba487f3a RP |
583 | * Object Formats:: Object File Formats |
584 | * Command Line:: Command Line | |
585 | * Input Files:: Input Files | |
586 | * Object:: Output (Object) File | |
587 | * Errors:: Error and Warning Messages | |
7a4c8e5c RP |
588 | @end menu |
589 | ||
242d9c06 | 590 | @node Manual |
d0281557 | 591 | @section Structure of this Manual |
66b818fb RP |
592 | |
593 | @cindex manual, structure and purpose | |
594 | This manual is intended to describe what you need to know to use | |
f009d0ab | 595 | @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including |
47342e8f | 596 | notation for symbols, constants, and expressions; the directives that |
f009d0ab | 597 | @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}. |
47342e8f | 598 | |
f009d0ab RP |
599 | @ifclear GENERIC |
600 | We also cover special features in the @value{TARGET} | |
601 | configuration of @code{@value{AS}}, including assembler directives. | |
602 | @end ifclear | |
603 | @ifset GENERIC | |
66b818fb | 604 | This manual also describes some of the machine-dependent features of |
09352a5d | 605 | various flavors of the assembler. |
f009d0ab | 606 | @end ifset |
93b45514 | 607 | |
66b818fb | 608 | @cindex machine instructions (not covered) |
47342e8f | 609 | On the other hand, this manual is @emph{not} intended as an introduction |
b50e59fe RP |
610 | to programming in assembly language---let alone programming in general! |
611 | In a similar vein, we make no attempt to introduce the machine | |
47342e8f RP |
612 | architecture; we do @emph{not} describe the instruction set, standard |
613 | mnemonics, registers or addressing modes that are standard to a | |
f009d0ab RP |
614 | particular architecture. |
615 | @ifset GENERIC | |
66b818fb | 616 | You may want to consult the manufacturer's |
b50e59fe | 617 | machine architecture manual for this information. |
f009d0ab RP |
618 | @end ifset |
619 | @ifclear GENERIC | |
620 | @ifset H8/300 | |
66b818fb | 621 | For information on the H8/300 machine instruction set, see @cite{H8/300 |
8d8ddccb RP |
622 | Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H, |
623 | see @cite{H8/300H Series Programming Manual} (Hitachi). | |
f009d0ab RP |
624 | @end ifset |
625 | @ifset H8/500 | |
626 | For information on the H8/500 machine instruction set, see @cite{H8/500 | |
627 | Series Programming Manual} (Hitachi M21T001). | |
628 | @end ifset | |
f009d0ab RP |
629 | @ifset SH |
630 | For information on the Hitachi SH machine instruction set, see | |
631 | @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.). | |
632 | @end ifset | |
f009d0ab | 633 | @ifset Z8000 |
2d8e0f62 | 634 | For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual} |
f009d0ab RP |
635 | @end ifset |
636 | @end ifclear | |
93b45514 | 637 | |
71dd3c40 | 638 | @c I think this is premature---doc@cygnus.com, 17jan1991 |
47342e8f | 639 | @ignore |
66b818fb | 640 | Throughout this manual, we assume that you are running @dfn{GNU}, |
93b45514 RP |
641 | the portable operating system from the @dfn{Free Software |
642 | Foundation, Inc.}. This restricts our attention to certain kinds of | |
8babef85 | 643 | computer (in particular, the kinds of computers that @sc{gnu} can run on); |
93b45514 RP |
644 | once this assumption is granted examples and definitions need less |
645 | qualification. | |
646 | ||
f009d0ab | 647 | @code{@value{AS}} is part of a team of programs that turn a high-level |
93b45514 RP |
648 | human-readable series of instructions into a low-level |
649 | computer-readable series of instructions. Different versions of | |
f009d0ab | 650 | @code{@value{AS}} are used for different kinds of computer. |
47342e8f | 651 | @end ignore |
93b45514 | 652 | |
b50e59fe RP |
653 | @c There used to be a section "Terminology" here, which defined |
654 | @c "contents", "byte", "word", and "long". Defining "word" to any | |
655 | @c particular size is confusing when the .word directive may generate 16 | |
656 | @c bits on one machine and 32 bits on another; in general, for the user | |
657 | @c version of this manual, none of these terms seem essential to define. | |
658 | @c They were used very little even in the former draft of the manual; | |
659 | @c this draft makes an effort to avoid them (except in names of | |
d0281557 RP |
660 | @c directives). |
661 | ||
242d9c06 | 662 | @node GNU Assembler |
3ffb03b1 | 663 | @section The GNU Assembler |
66b818fb | 664 | |
8babef85 | 665 | @sc{gnu} @code{as} is really a family of assemblers. |
f009d0ab RP |
666 | @ifclear GENERIC |
667 | This manual describes @code{@value{AS}}, a member of that family which is | |
668 | configured for the @value{TARGET} architectures. | |
669 | @end ifclear | |
8babef85 | 670 | If you use (or have used) the @sc{gnu} assembler on one architecture, you |
7a4c8e5c RP |
671 | should find a fairly similar environment when you use it on another |
672 | architecture. Each version has much in common with the others, | |
673 | including object file formats, most assembler directives (often called | |
9ebc250f | 674 | @dfn{pseudo-ops}) and assembler syntax.@refill |
d0281557 | 675 | |
3ffb03b1 | 676 | @cindex purpose of @sc{gnu} assembler |
f009d0ab | 677 | @code{@value{AS}} is primarily intended to assemble the output of the |
8babef85 | 678 | @sc{gnu} C compiler @code{@value{GCC}} for use by the linker |
f009d0ab RP |
679 | @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}} |
680 | assemble correctly everything that other assemblers for the same | |
681 | machine would assemble. | |
682 | @ifset VAX | |
683 | Any exceptions are documented explicitly (@pxref{Machine Dependencies}). | |
684 | @end ifset | |
685 | @ifset M680X0 | |
686 | @c This remark should appear in generic version of manual; assumption | |
687 | @c here is that generic version sets M680x0. | |
688 | This doesn't mean @code{@value{AS}} always uses the same syntax as another | |
b50e59fe RP |
689 | assembler for the same architecture; for example, we know of several |
690 | incompatible versions of 680x0 assembly language syntax. | |
f009d0ab | 691 | @end ifset |
47342e8f | 692 | |
f009d0ab | 693 | Unlike older assemblers, @code{@value{AS}} is designed to assemble a source |
b50e59fe | 694 | program in one pass of the source file. This has a subtle impact on the |
7a4c8e5c | 695 | @kbd{.org} directive (@pxref{Org,,@code{.org}}). |
93b45514 | 696 | |
242d9c06 | 697 | @node Object Formats |
d0281557 | 698 | @section Object File Formats |
66b818fb RP |
699 | |
700 | @cindex object file format | |
8babef85 | 701 | The @sc{gnu} assembler can be configured to produce several alternative |
7d7ecbdd RP |
702 | object file formats. For the most part, this does not affect how you |
703 | write assembly language programs; but directives for debugging symbols | |
704 | are typically different in different file formats. @xref{Symbol | |
705 | Attributes,,Symbol Attributes}. | |
f009d0ab RP |
706 | @ifclear GENERIC |
707 | @ifclear MULTI-OBJ | |
708 | On the @value{TARGET}, @code{@value{AS}} is configured to produce | |
709 | @value{OBJ-NAME} format object files. | |
710 | @end ifclear | |
711 | @c The following should exhaust all configs that set MULTI-OBJ, ideally | |
712 | @ifset A29K | |
713 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
24b1493d | 714 | @code{a.out} or COFF format object files. |
f009d0ab RP |
715 | @end ifset |
716 | @ifset I960 | |
717 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
718 | @code{b.out} or COFF format object files. | |
719 | @end ifset | |
9dcf8057 JL |
720 | @ifset HPPA |
721 | On the @value{TARGET}, @code{@value{AS}} can be configured to produce either | |
722 | SOM or ELF format object files. | |
723 | @end ifset | |
f009d0ab | 724 | @end ifclear |
d0281557 | 725 | |
242d9c06 | 726 | @node Command Line |
b50e59fe | 727 | @section Command Line |
93b45514 | 728 | |
66b818fb | 729 | @cindex command line conventions |
f009d0ab | 730 | After the program name @code{@value{AS}}, the command line may contain |
66b818fb | 731 | options and file names. Options may appear in any order, and may be |
93b45514 RP |
732 | before, after, or between file names. The order of file names is |
733 | significant. | |
734 | ||
66b818fb RP |
735 | @cindex standard input, as input file |
736 | @kindex -- | |
47342e8f | 737 | @file{--} (two hyphens) by itself names the standard input file |
f009d0ab | 738 | explicitly, as one of the files for @code{@value{AS}} to assemble. |
47342e8f | 739 | |
66b818fb | 740 | @cindex options, command line |
93b45514 RP |
741 | Except for @samp{--} any command line argument that begins with a |
742 | hyphen (@samp{-}) is an option. Each option changes the behavior of | |
f009d0ab | 743 | @code{@value{AS}}. No option changes the way another option works. An |
47342e8f | 744 | option is a @samp{-} followed by one or more letters; the case of |
b50e59fe | 745 | the letter is important. All options are optional. |
93b45514 RP |
746 | |
747 | Some options expect exactly one file name to follow them. The file | |
748 | name may either immediately follow the option's letter (compatible | |
8babef85 | 749 | with older assemblers) or it may be the next command argument (@sc{gnu} |
93b45514 RP |
750 | standard). These two command lines are equivalent: |
751 | ||
d0281557 | 752 | @smallexample |
f009d0ab RP |
753 | @value{AS} -o my-object-file.o mumble.s |
754 | @value{AS} -omy-object-file.o mumble.s | |
d0281557 | 755 | @end smallexample |
93b45514 | 756 | |
242d9c06 | 757 | @node Input Files |
47342e8f | 758 | @section Input Files |
93b45514 | 759 | |
66b818fb RP |
760 | @cindex input |
761 | @cindex source program | |
762 | @cindex files, input | |
47342e8f | 763 | We use the phrase @dfn{source program}, abbreviated @dfn{source}, to |
f009d0ab | 764 | describe the program input to one run of @code{@value{AS}}. The program may |
93b45514 RP |
765 | be in one or more files; how the source is partitioned into files |
766 | doesn't change the meaning of the source. | |
767 | ||
b50e59fe | 768 | @c I added "con" prefix to "catenation" just to prove I can overcome my |
71dd3c40 | 769 | @c APL training... doc@cygnus.com |
b50e59fe | 770 | The source program is a concatenation of the text in all the files, in the |
47342e8f | 771 | order specified. |
93b45514 | 772 | |
f009d0ab | 773 | Each time you run @code{@value{AS}} it assembles exactly one source |
47342e8f | 774 | program. The source program is made up of one or more files. |
93b45514 RP |
775 | (The standard input is also a file.) |
776 | ||
f009d0ab | 777 | You give @code{@value{AS}} a command line that has zero or more input file |
93b45514 RP |
778 | names. The input files are read (from left file name to right). A |
779 | command line argument (in any position) that has no special meaning | |
d0281557 | 780 | is taken to be an input file name. |
93b45514 | 781 | |
f009d0ab RP |
782 | If you give @code{@value{AS}} no file names it attempts to read one input file |
783 | from the @code{@value{AS}} standard input, which is normally your terminal. You | |
784 | may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program | |
d0281557 | 785 | to assemble. |
93b45514 | 786 | |
47342e8f RP |
787 | Use @samp{--} if you need to explicitly name the standard input file |
788 | in your command line. | |
93b45514 | 789 | |
05a0e43b | 790 | If the source is empty, @code{@value{AS}} produces a small, empty object |
d0281557 | 791 | file. |
b50e59fe | 792 | |
7a4c8e5c | 793 | @subheading Filenames and Line-numbers |
66b818fb RP |
794 | |
795 | @cindex input file linenumbers | |
796 | @cindex line numbers, in input files | |
797 | There are two ways of locating a line in the input file (or files) and | |
798 | either may be used in reporting error messages. One way refers to a line | |
93b45514 | 799 | number in a physical file; the other refers to a line number in a |
66b818fb | 800 | ``logical'' file. @xref{Errors, ,Error and Warning Messages}. |
93b45514 RP |
801 | |
802 | @dfn{Physical files} are those files named in the command line given | |
f009d0ab | 803 | to @code{@value{AS}}. |
93b45514 | 804 | |
47342e8f RP |
805 | @dfn{Logical files} are simply names declared explicitly by assembler |
806 | directives; they bear no relation to physical files. Logical file names | |
f009d0ab | 807 | help error messages reflect the original source file, when @code{@value{AS}} |
7a4c8e5c | 808 | source is itself synthesized from other files. |
f009d0ab | 809 | @xref{App-File,,@code{.app-file}}. |
93b45514 | 810 | |
242d9c06 | 811 | @node Object |
93b45514 | 812 | @section Output (Object) File |
66b818fb RP |
813 | |
814 | @cindex object file | |
815 | @cindex output file | |
816 | @kindex a.out | |
817 | @kindex .o | |
f009d0ab | 818 | Every time you run @code{@value{AS}} it produces an output file, which is |
93b45514 | 819 | your assembly language program translated into numbers. This file |
65fbb2d7 RP |
820 | is the object file. Its default name is |
821 | @ifclear BOUT | |
822 | @code{a.out}. | |
823 | @end ifclear | |
f009d0ab | 824 | @ifset BOUT |
f009d0ab | 825 | @ifset GENERIC |
65fbb2d7 | 826 | @code{a.out}, or |
f009d0ab | 827 | @end ifset |
65fbb2d7 | 828 | @code{b.out} when @code{@value{AS}} is configured for the Intel 80960. |
f009d0ab | 829 | @end ifset |
65fbb2d7 RP |
830 | You can give it another name by using the @code{-o} option. Conventionally, |
831 | object file names end with @file{.o}. The default name is used for historical | |
832 | reasons: older assemblers were capable of assembling self-contained programs | |
833 | directly into a runnable program. (For some formats, this isn't currently | |
834 | possible, but it can be done for the @code{a.out} format.) | |
93b45514 | 835 | |
66b818fb RP |
836 | @cindex linker |
837 | @kindex ld | |
f009d0ab RP |
838 | The object file is meant for input to the linker @code{@value{LD}}. It contains |
839 | assembled program code, information to help @code{@value{LD}} integrate | |
b50e59fe | 840 | the assembled program into a runnable file, and (optionally) symbolic |
d0281557 | 841 | information for the debugger. |
93b45514 | 842 | |
66b818fb | 843 | @c link above to some info file(s) like the description of a.out. |
71dd3c40 | 844 | @c don't forget to describe @sc{gnu} info as well as Unix lossage. |
93b45514 | 845 | |
242d9c06 | 846 | @node Errors |
93b45514 RP |
847 | @section Error and Warning Messages |
848 | ||
66b818fb RP |
849 | @cindex error messsages |
850 | @cindex warning messages | |
3ffb03b1 | 851 | @cindex messages from assembler |
f009d0ab | 852 | @code{@value{AS}} may write warnings and error messages to the standard error |
66b818fb | 853 | file (usually your terminal). This should not happen when a compiler |
f009d0ab RP |
854 | runs @code{@value{AS}} automatically. Warnings report an assumption made so |
855 | that @code{@value{AS}} could keep assembling a flawed program; errors report a | |
b50e59fe | 856 | grave problem that stops the assembly. |
93b45514 | 857 | |
66b818fb | 858 | @cindex format of warning messages |
93b45514 | 859 | Warning messages have the format |
66b818fb | 860 | |
d0281557 | 861 | @smallexample |
b50e59fe | 862 | file_name:@b{NNN}:Warning Message Text |
d0281557 | 863 | @end smallexample |
66b818fb | 864 | |
0b5b143a | 865 | @noindent |
66b818fb | 866 | @cindex line numbers, in warnings/errors |
f009d0ab RP |
867 | (where @b{NNN} is a line number). If a logical file name has been given |
868 | (@pxref{App-File,,@code{.app-file}}) it is used for the filename, | |
869 | otherwise the name of the current input file is used. If a logical line | |
870 | number was given | |
871 | @ifset GENERIC | |
872 | (@pxref{Line,,@code{.line}}) | |
873 | @end ifset | |
874 | @ifclear GENERIC | |
875 | @ifclear A29K | |
7a4c8e5c | 876 | (@pxref{Line,,@code{.line}}) |
f009d0ab RP |
877 | @end ifclear |
878 | @ifset A29K | |
7a4c8e5c | 879 | (@pxref{Ln,,@code{.ln}}) |
f009d0ab RP |
880 | @end ifset |
881 | @end ifclear | |
63f5d795 | 882 | then it is used to calculate the number printed, |
b50e59fe RP |
883 | otherwise the actual line in the current source file is printed. The |
884 | message text is intended to be self explanatory (in the grand Unix | |
f009d0ab | 885 | tradition). |
93b45514 | 886 | |
66b818fb | 887 | @cindex format of error messages |
93b45514 | 888 | Error messages have the format |
d0281557 | 889 | @smallexample |
b50e59fe | 890 | file_name:@b{NNN}:FATAL:Error Message Text |
d0281557 | 891 | @end smallexample |
47342e8f | 892 | The file name and line number are derived as for warning |
93b45514 RP |
893 | messages. The actual message text may be rather less explanatory |
894 | because many of them aren't supposed to happen. | |
895 | ||
242d9c06 | 896 | @node Invoking |
7a4c8e5c | 897 | @chapter Command-Line Options |
66b818fb | 898 | |
3ffb03b1 | 899 | @cindex options, all versions of assembler |
66b818fb | 900 | This chapter describes command-line options available in @emph{all} |
8babef85 | 901 | versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific |
f009d0ab RP |
902 | @ifclear GENERIC |
903 | to the @value{TARGET}. | |
904 | @end ifclear | |
905 | @ifset GENERIC | |
0b5b143a | 906 | to particular machine architectures. |
f009d0ab | 907 | @end ifset |
0193302d | 908 | |
8babef85 | 909 | If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2), you |
0193302d KR |
910 | can use the @samp{-Wa} option to pass arguments through to the |
911 | assembler. The assembler arguments must be separated from each other | |
912 | (and the @samp{-Wa}) by commas. For example: | |
913 | ||
914 | @smallexample | |
915 | gcc -c -g -O -Wa,-alh,-L file.c | |
916 | @end smallexample | |
917 | ||
05a0e43b RP |
918 | @noindent |
919 | emits a listing to standard output with high-level | |
0193302d KR |
920 | and assembly source. |
921 | ||
81fcb3ff RP |
922 | Usually you do not need to use this @samp{-Wa} mechanism, since many compiler |
923 | command-line options are automatically passed to the assembler by the compiler. | |
8babef85 | 924 | (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see |
81fcb3ff RP |
925 | precisely what options it passes to each compilation pass, including the |
926 | assembler.) | |
d0281557 | 927 | |
f009d0ab | 928 | @menu |
35cfacf0 | 929 | * a:: -a[cdhlns] enable listings |
f009d0ab RP |
930 | * D:: -D for compatibility |
931 | * f:: -f to work faster | |
932 | * I:: -I for .include search path | |
933 | @ifclear DIFF-TBL-KLUGE | |
934 | * K:: -K for compatibility | |
935 | @end ifclear | |
936 | @ifset DIFF-TBL-KLUGE | |
937 | * K:: -K for difference tables | |
938 | @end ifset | |
939 | ||
940 | * L:: -L to retain local labels | |
79e15b8a | 941 | * M:: -M or --mri to assemble in MRI compatibility mode |
8a51eeaf | 942 | * MD:: --MD for dependency tracking |
f009d0ab RP |
943 | * o:: -o to name the object file |
944 | * R:: -R to join data and text sections | |
62e59d28 | 945 | * statistics:: --statistics to see statistics about assembly |
f009d0ab RP |
946 | * v:: -v to announce version |
947 | * W:: -W to suppress warnings | |
62e59d28 | 948 | * Z:: -Z to make object file even after errors |
f009d0ab RP |
949 | @end menu |
950 | ||
951 | @node a | |
35cfacf0 | 952 | @section Enable Listings: @code{-a[cdhlns]} |
66b818fb RP |
953 | |
954 | @kindex -a | |
35cfacf0 | 955 | @kindex -ac |
0193302d KR |
956 | @kindex -ad |
957 | @kindex -ah | |
66b818fb | 958 | @kindex -al |
0193302d | 959 | @kindex -an |
66b818fb RP |
960 | @kindex -as |
961 | @cindex listings, enabling | |
962 | @cindex assembly listings, enabling | |
0193302d KR |
963 | |
964 | These options enable listing output from the assembler. By itself, | |
965 | @samp{-a} requests high-level, assembly, and symbols listing. | |
dd565f85 | 966 | You can use other letters to select specific options for the list: |
0193302d KR |
967 | @samp{-ah} requests a high-level language listing, |
968 | @samp{-al} requests an output-program assembly listing, and | |
969 | @samp{-as} requests a symbol table listing. | |
970 | High-level listings require that a compiler debugging option like | |
971 | @samp{-g} be used, and that assembly listings (@samp{-al}) be requested | |
972 | also. | |
973 | ||
35cfacf0 ILT |
974 | Use the @samp{-ac} option to omit false conditionals from a listing. Any lines |
975 | which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any | |
976 | other conditional), or a true @code{.if} followed by an @code{.else}, will be | |
977 | omitted from the listing. | |
978 | ||
dd565f85 | 979 | Use the @samp{-ad} option to omit debugging directives from the |
0193302d | 980 | listing. |
66b818fb RP |
981 | |
982 | Once you have specified one of these options, you can further control | |
983 | listing output and its appearance using the directives @code{.list}, | |
984 | @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and | |
985 | @code{.sbttl}. | |
0193302d | 986 | The @samp{-an} option turns off all forms processing. |
66b818fb RP |
987 | If you do not request listing output with one of the @samp{-a} options, the |
988 | listing-control directives have no effect. | |
989 | ||
0193302d KR |
990 | The letters after @samp{-a} may be combined into one option, |
991 | @emph{e.g.}, @samp{-aln}. | |
992 | ||
f009d0ab | 993 | @node D |
66b818fb RP |
994 | @section @code{-D} |
995 | ||
996 | @kindex -D | |
b50e59fe | 997 | This option has no effect whatsoever, but it is accepted to make it more |
05a0e43b | 998 | likely that scripts written for other assemblers also work with |
f009d0ab | 999 | @code{@value{AS}}. |
b50e59fe | 1000 | |
f009d0ab | 1001 | @node f |
66b818fb RP |
1002 | @section Work Faster: @code{-f} |
1003 | ||
1004 | @kindex -f | |
1005 | @cindex trusted compiler | |
1006 | @cindex faster processing (@code{-f}) | |
93b45514 | 1007 | @samp{-f} should only be used when assembling programs written by a |
9dcf8057 | 1008 | (trusted) compiler. @samp{-f} stops the assembler from doing whitespace |
05a0e43b RP |
1009 | and comment preprocessing on |
1010 | the input file(s) before assembling them. @xref{Preprocessing, | |
1011 | ,Preprocessing}. | |
66b818fb | 1012 | |
b50e59fe | 1013 | @quotation |
05a0e43b RP |
1014 | @emph{Warning:} if you use @samp{-f} when the files actually need to be |
1015 | preprocessed (if they contain comments, for example), @code{@value{AS}} does | |
1016 | not work correctly. | |
b50e59fe RP |
1017 | @end quotation |
1018 | ||
f009d0ab | 1019 | @node I |
66b818fb RP |
1020 | @section @code{.include} search path: @code{-I} @var{path} |
1021 | ||
1022 | @kindex -I @var{path} | |
1023 | @cindex paths for @code{.include} | |
1024 | @cindex search path for @code{.include} | |
1025 | @cindex @code{include} directive search path | |
d0281557 | 1026 | Use this option to add a @var{path} to the list of directories |
05a0e43b | 1027 | @code{@value{AS}} searches for files specified in @code{.include} |
7a4c8e5c RP |
1028 | directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as |
1029 | many times as necessary to include a variety of paths. The current | |
f009d0ab | 1030 | working directory is always searched first; after that, @code{@value{AS}} |
7a4c8e5c RP |
1031 | searches any @samp{-I} directories in the same order as they were |
1032 | specified (left to right) on the command line. | |
d0281557 | 1033 | |
f009d0ab | 1034 | @node K |
80381063 | 1035 | @section Difference Tables: @code{-K} |
66b818fb | 1036 | |
80381063 | 1037 | @kindex -K |
f009d0ab RP |
1038 | @ifclear DIFF-TBL-KLUGE |
1039 | On the @value{TARGET} family, this option is allowed, but has no effect. It is | |
8babef85 | 1040 | permitted for compatibility with the @sc{gnu} assembler on other platforms, |
d0281557 | 1041 | where it can be used to warn when the assembler alters the machine code |
f009d0ab | 1042 | generated for @samp{.word} directives in difference tables. The @value{TARGET} |
b50e59fe RP |
1043 | family does not have the addressing limitations that sometimes lead to this |
1044 | alteration on other platforms. | |
f009d0ab | 1045 | @end ifclear |
b50e59fe | 1046 | |
f009d0ab | 1047 | @ifset DIFF-TBL-KLUGE |
66b818fb RP |
1048 | @cindex difference tables, warning |
1049 | @cindex warning for altered difference tables | |
f009d0ab | 1050 | @code{@value{AS}} sometimes alters the code emitted for directives of the form |
7a4c8e5c | 1051 | @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}. |
80381063 | 1052 | You can use the @samp{-K} option if you want a warning issued when this |
d0281557 | 1053 | is done. |
f009d0ab | 1054 | @end ifset |
47342e8f | 1055 | |
f009d0ab | 1056 | @node L |
66b818fb RP |
1057 | @section Include Local Labels: @code{-L} |
1058 | ||
1059 | @kindex -L | |
1060 | @cindex local labels, retaining in output | |
b50e59fe | 1061 | Labels beginning with @samp{L} (upper case only) are called @dfn{local |
05a0e43b | 1062 | labels}. @xref{Symbol Names}. Normally you do not see such labels when |
47342e8f | 1063 | debugging, because they are intended for the use of programs (like |
b50e59fe | 1064 | compilers) that compose assembler programs, not for your notice. |
05a0e43b | 1065 | Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not |
b50e59fe | 1066 | normally debug with them. |
93b45514 | 1067 | |
f009d0ab | 1068 | This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols |
93b45514 | 1069 | in the object file. Usually if you do this you also tell the linker |
f009d0ab | 1070 | @code{@value{LD}} to preserve symbols whose names begin with @samp{L}. |
93b45514 | 1071 | |
9dcf8057 JL |
1072 | By default, a local label is any label beginning with @samp{L}, but each |
1073 | target is allowed to redefine the local label prefix. | |
509d5555 JL |
1074 | @ifset HPPA |
1075 | On the HPPA local labels begin with @samp{L$}. | |
1076 | @end ifset | |
3ffb03b1 DE |
1077 | @ifset ARM |
1078 | @samp{;} for the ARM family; | |
99c4053d | 1079 | @end ifset |
9dcf8057 | 1080 | |
79e15b8a ILT |
1081 | @node M |
1082 | @section Assemble in MRI Compatibility Mode: @code{-M} | |
1083 | ||
1084 | @kindex -M | |
1085 | @cindex MRI compatibility mode | |
1086 | The @code{-M} or @code{--mri} option selects MRI compatibility mode. This | |
1087 | changes the syntax and pseudo-op handling of @code{@value{AS}} to make it | |
71dd3c40 ILT |
1088 | compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the |
1089 | configured target) assembler from Microtec Research. The exact nature of the | |
1090 | MRI syntax will not be documented here; see the MRI manuals for more | |
7d99e8af ILT |
1091 | information. Note in particular that the handling of macros and macro |
1092 | arguments is somewhat different. The purpose of this option is to permit | |
1093 | assembling existing MRI assembler code using @code{@value{AS}}. | |
79e15b8a ILT |
1094 | |
1095 | The MRI compatibility is not complete. Certain operations of the MRI assembler | |
1096 | depend upon its object file format, and can not be supported using other object | |
1097 | file formats. Supporting these would require enhancing each object file format | |
1098 | individually. These are: | |
1099 | ||
1100 | @itemize @bullet | |
1101 | @item global symbols in common section | |
1102 | ||
71dd3c40 | 1103 | The m68k MRI assembler supports common sections which are merged by the linker. |
79e15b8a ILT |
1104 | Other object file formats do not support this. @code{@value{AS}} handles |
1105 | common sections by treating them as a single common symbol. It permits local | |
1106 | symbols to be defined within a common section, but it can not support global | |
1107 | symbols, since it has no way to describe them. | |
1108 | ||
1109 | @item complex relocations | |
1110 | ||
71dd3c40 | 1111 | The MRI assemblers support relocations against a negated section address, and |
79e15b8a ILT |
1112 | relocations which combine the start addresses of two or more sections. These |
1113 | are not support by other object file formats. | |
1114 | ||
1115 | @item @code{END} pseudo-op specifying start address | |
1116 | ||
1117 | The MRI @code{END} pseudo-op permits the specification of a start address. | |
1118 | This is not supported by other object file formats. The start address may | |
1119 | instead be specified using the @code{-e} option to the linker, or in a linker | |
1120 | script. | |
1121 | ||
71dd3c40 | 1122 | @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops |
79e15b8a | 1123 | |
71dd3c40 ILT |
1124 | The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module |
1125 | name to the output file. This is not supported by other object file formats. | |
79e15b8a ILT |
1126 | |
1127 | @item @code{ORG} pseudo-op | |
1128 | ||
71dd3c40 ILT |
1129 | The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given |
1130 | address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op, | |
1131 | which changes the location within the current section. Absolute sections are | |
1132 | not supported by other object file formats. The address of a section may be | |
79e15b8a ILT |
1133 | assigned within a linker script. |
1134 | @end itemize | |
1135 | ||
1136 | There are some other features of the MRI assembler which are not supported by | |
1137 | @code{@value{AS}}, typically either because they are difficult or because they | |
1138 | seem of little consequence. Some of these may be supported in future releases. | |
1139 | ||
1140 | @itemize @bullet | |
1141 | ||
79e15b8a ILT |
1142 | @item EBCDIC strings |
1143 | ||
1144 | EBCDIC strings are not supported. | |
1145 | ||
1146 | @item packed binary coded decimal | |
1147 | ||
1148 | Packed binary coded decimal is not supported. This means that the @code{DC.P} | |
1149 | and @code{DCB.P} pseudo-ops are not supported. | |
1150 | ||
1151 | @item @code{FEQU} pseudo-op | |
1152 | ||
71dd3c40 | 1153 | The m68k @code{FEQU} pseudo-op is not supported. |
79e15b8a ILT |
1154 | |
1155 | @item @code{NOOBJ} pseudo-op | |
1156 | ||
71dd3c40 | 1157 | The m68k @code{NOOBJ} pseudo-op is not supported. |
79e15b8a ILT |
1158 | |
1159 | @item @code{OPT} branch control options | |
1160 | ||
71dd3c40 | 1161 | The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB}, |
79e15b8a ILT |
1162 | @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically |
1163 | relaxes all branches, whether forward or backward, to an appropriate size, so | |
1164 | these options serve no purpose. | |
1165 | ||
1166 | @item @code{OPT} list control options | |
1167 | ||
71dd3c40 | 1168 | The following m68k @code{OPT} list control options are ignored: @code{C}, |
79e15b8a ILT |
1169 | @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M}, |
1170 | @code{MEX}, @code{MC}, @code{MD}, @code{X}. | |
1171 | ||
1172 | @item other @code{OPT} options | |
1173 | ||
71dd3c40 | 1174 | The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O}, |
79e15b8a ILT |
1175 | @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}. |
1176 | ||
1177 | @item @code{OPT} @code{D} option is default | |
1178 | ||
71dd3c40 | 1179 | The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler. |
79e15b8a ILT |
1180 | @code{OPT NOD} may be used to turn it off. |
1181 | ||
1182 | @item @code{XREF} pseudo-op. | |
1183 | ||
71dd3c40 ILT |
1184 | The m68k @code{XREF} pseudo-op is ignored. |
1185 | ||
1186 | @item @code{.debug} pseudo-op | |
1187 | ||
1188 | The i960 @code{.debug} pseudo-op is not supported. | |
1189 | ||
1190 | @item @code{.extended} pseudo-op | |
1191 | ||
1192 | The i960 @code{.extended} pseudo-op is not supported. | |
1193 | ||
1194 | @item @code{.list} pseudo-op. | |
1195 | ||
1196 | The various options of the i960 @code{.list} pseudo-op are not supported. | |
1197 | ||
1198 | @item @code{.optimize} pseudo-op | |
1199 | ||
1200 | The i960 @code{.optimize} pseudo-op is not supported. | |
1201 | ||
1202 | @item @code{.output} pseudo-op | |
1203 | ||
1204 | The i960 @code{.output} pseudo-op is not supported. | |
1205 | ||
1206 | @item @code{.setreal} pseudo-op | |
1207 | ||
1208 | The i960 @code{.setreal} pseudo-op is not supported. | |
79e15b8a | 1209 | |
79e15b8a ILT |
1210 | @end itemize |
1211 | ||
8a51eeaf TT |
1212 | @node MD |
1213 | @section Dependency tracking: @code{--MD} | |
1214 | ||
1215 | @kindex --MD | |
1216 | @cindex dependency tracking | |
1217 | @cindex make rules | |
1218 | ||
1219 | @code{@value{AS}} can generate a dependency file for the file it creates. This | |
1220 | file consists of a single rule suitable for @code{make} describing the | |
1221 | dependencies of the main source file. | |
1222 | ||
1223 | The rule is written to the file named in its argument. | |
1224 | ||
1225 | This feature is used in the automatic updating of makefiles. | |
1226 | ||
f009d0ab | 1227 | @node o |
66b818fb RP |
1228 | @section Name the Object File: @code{-o} |
1229 | ||
1230 | @kindex -o | |
1231 | @cindex naming object file | |
1232 | @cindex object file name | |
f009d0ab | 1233 | There is always one object file output when you run @code{@value{AS}}. By |
9ebc250f | 1234 | default it has the name |
f009d0ab RP |
1235 | @ifset GENERIC |
1236 | @ifset I960 | |
1237 | @file{a.out} (or @file{b.out}, for Intel 960 targets only). | |
1238 | @end ifset | |
1239 | @ifclear I960 | |
9ebc250f | 1240 | @file{a.out}. |
f009d0ab RP |
1241 | @end ifclear |
1242 | @end ifset | |
1243 | @ifclear GENERIC | |
1244 | @ifset I960 | |
9ebc250f | 1245 | @file{b.out}. |
f009d0ab RP |
1246 | @end ifset |
1247 | @ifclear I960 | |
9ebc250f | 1248 | @file{a.out}. |
f009d0ab RP |
1249 | @end ifclear |
1250 | @end ifclear | |
1251 | You use this option (which takes exactly one filename) to give the | |
1252 | object file a different name. | |
93b45514 | 1253 | |
05a0e43b | 1254 | Whatever the object file is called, @code{@value{AS}} overwrites any |
93b45514 RP |
1255 | existing file of the same name. |
1256 | ||
f009d0ab | 1257 | @node R |
66b818fb RP |
1258 | @section Join Data and Text Sections: @code{-R} |
1259 | ||
1260 | @kindex -R | |
1261 | @cindex data and text sections, joining | |
1262 | @cindex text and data sections, joining | |
1263 | @cindex joining text and data sections | |
1264 | @cindex merging text and data sections | |
f009d0ab | 1265 | @code{-R} tells @code{@value{AS}} to write the object file as if all |
24b1493d | 1266 | data-section data lives in the text section. This is only done at |
93b45514 | 1267 | the very last moment: your binary data are the same, but data |
24b1493d | 1268 | section parts are relocated differently. The data section part of |
9ebc250f | 1269 | your object file is zero bytes long because all its bytes are |
24b1493d | 1270 | appended to the text section. (@xref{Sections,,Sections and Relocation}.) |
93b45514 | 1271 | |
b50e59fe | 1272 | When you specify @code{-R} it would be possible to generate shorter |
05a0e43b | 1273 | address displacements (because we do not have to cross between text and |
24b1493d | 1274 | data section). We refrain from doing this simply for compatibility with |
f009d0ab | 1275 | older versions of @code{@value{AS}}. In future, @code{-R} may work this way. |
93b45514 | 1276 | |
f009d0ab RP |
1277 | @ifset COFF |
1278 | When @code{@value{AS}} is configured for COFF output, | |
66b818fb | 1279 | this option is only useful if you use sections named @samp{.text} and |
f009d0ab RP |
1280 | @samp{.data}. |
1281 | @end ifset | |
66b818fb | 1282 | |
9dcf8057 | 1283 | @ifset HPPA |
05a0e43b RP |
1284 | @code{-R} is not supported for any of the HPPA targets. Using |
1285 | @code{-R} generates a warning from @code{@value{AS}}. | |
9dcf8057 JL |
1286 | @end ifset |
1287 | ||
62e59d28 | 1288 | @node statistics |
81fcb3ff | 1289 | @section Display Assembly Statistics: @code{--statistics} |
62e59d28 RP |
1290 | |
1291 | @kindex --statistics | |
1292 | @cindex statistics, about assembly | |
1293 | @cindex time, total for assembly | |
1294 | @cindex space used, maximum for assembly | |
1295 | Use @samp{--statistics} to display two statistics about the resources used by | |
1296 | @code{@value{AS}}: the maximum amount of space allocated during the assembly | |
1297 | (in bytes), and the total execution time taken for the assembly (in @sc{cpu} | |
1298 | seconds). | |
1299 | ||
f009d0ab | 1300 | @node v |
66b818fb RP |
1301 | @section Announce Version: @code{-v} |
1302 | ||
1303 | @kindex -v | |
1304 | @kindex -version | |
3ffb03b1 DE |
1305 | @cindex assembler version |
1306 | @cindex version of assembler | |
7d7ecbdd RP |
1307 | You can find out what version of as is running by including the |
1308 | option @samp{-v} (which you can also spell as @samp{-version}) on the | |
1309 | command line. | |
1310 | ||
f009d0ab | 1311 | @node W |
66b818fb RP |
1312 | @section Suppress Warnings: @code{-W} |
1313 | ||
1314 | @kindex -W | |
1315 | @cindex suppressing warnings | |
1316 | @cindex warnings, suppressing | |
f009d0ab | 1317 | @code{@value{AS}} should never give a warning or error message when |
93b45514 | 1318 | assembling compiler output. But programs written by people often |
f009d0ab | 1319 | cause @code{@value{AS}} to give a warning that a particular assumption was |
93b45514 | 1320 | made. All such warnings are directed to the standard error file. |
47342e8f RP |
1321 | If you use this option, no warnings are issued. This option only |
1322 | affects the warning messages: it does not change any particular of how | |
f009d0ab | 1323 | @code{@value{AS}} assembles your file. Errors, which stop the assembly, are |
93b45514 RP |
1324 | still reported. |
1325 | ||
62e59d28 RP |
1326 | @node Z |
1327 | @section Generate Object File in Spite of Errors: @code{-Z} | |
1328 | @cindex object file, after errors | |
1329 | @cindex errors, continuing after | |
1330 | After an error message, @code{@value{AS}} normally produces no output. If for | |
1331 | some reason you are interested in object file output even after | |
1332 | @code{@value{AS}} gives an error message on your program, use the @samp{-Z} | |
1333 | option. If there are any errors, @code{@value{AS}} continues anyways, and | |
1334 | writes an object file after a final warning message of the form @samp{@var{n} | |
1335 | errors, @var{m} warnings, generating bad object file.} | |
1336 | ||
242d9c06 | 1337 | @node Syntax |
d0281557 | 1338 | @chapter Syntax |
66b818fb RP |
1339 | |
1340 | @cindex machine-independent syntax | |
1341 | @cindex syntax, machine-independent | |
47342e8f | 1342 | This chapter describes the machine-independent syntax allowed in a |
f009d0ab RP |
1343 | source file. @code{@value{AS}} syntax is similar to what many other |
1344 | assemblers use; it is inspired by the BSD 4.2 | |
1345 | @ifclear VAX | |
1346 | assembler. | |
1347 | @end ifclear | |
1348 | @ifset VAX | |
1349 | assembler, except that @code{@value{AS}} does not assemble Vax bit-fields. | |
1350 | @end ifset | |
b50e59fe | 1351 | |
7a4c8e5c | 1352 | @menu |
05a0e43b | 1353 | * Preprocessing:: Preprocessing |
ba487f3a RP |
1354 | * Whitespace:: Whitespace |
1355 | * Comments:: Comments | |
1356 | * Symbol Intro:: Symbols | |
1357 | * Statements:: Statements | |
1358 | * Constants:: Constants | |
7a4c8e5c RP |
1359 | @end menu |
1360 | ||
05a0e43b RP |
1361 | @node Preprocessing |
1362 | @section Preprocessing | |
93b45514 | 1363 | |
66b818fb | 1364 | @cindex preprocessing |
05a0e43b | 1365 | The @code{@value{AS}} internal preprocessor: |
b50e59fe | 1366 | @itemize @bullet |
66b818fb | 1367 | @cindex whitespace, removed by preprocessor |
b50e59fe RP |
1368 | @item |
1369 | adjusts and removes extra whitespace. It leaves one space or tab before | |
1370 | the keywords on a line, and turns any other whitespace on the line into | |
1371 | a single space. | |
93b45514 | 1372 | |
66b818fb | 1373 | @cindex comments, removed by preprocessor |
b50e59fe RP |
1374 | @item |
1375 | removes all comments, replacing them with a single space, or an | |
1376 | appropriate number of newlines. | |
93b45514 | 1377 | |
66b818fb | 1378 | @cindex constants, converted by preprocessor |
b50e59fe RP |
1379 | @item |
1380 | converts character constants into the appropriate numeric values. | |
1381 | @end itemize | |
1382 | ||
dd565f85 | 1383 | It does not do macro processing, include file handling, or |
05a0e43b | 1384 | anything else you may get from your C compiler's preprocessor. You can |
9dcf8057 | 1385 | do include file processing with the @code{.include} directive |
dd565f85 RP |
1386 | (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver |
1387 | to get other ``CPP'' style preprocessing, by giving the input file a | |
1388 | @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of | |
1389 | Output, gcc.info, Using GNU CC}. | |
9dcf8057 | 1390 | |
b50e59fe | 1391 | Excess whitespace, comments, and character constants |
93b45514 | 1392 | cannot be used in the portions of the input text that are not |
05a0e43b | 1393 | preprocessed. |
93b45514 | 1394 | |
66b818fb RP |
1395 | @cindex turning preprocessing on and off |
1396 | @cindex preprocessing, turning on and off | |
1397 | @kindex #NO_APP | |
1398 | @kindex #APP | |
05a0e43b RP |
1399 | If the first line of an input file is @code{#NO_APP} or if you use the |
1400 | @samp{-f} option, whitespace and comments are not removed from the input file. | |
1401 | Within an input file, you can ask for whitespace and comment removal in | |
1402 | specific portions of the by putting a line that says @code{#APP} before the | |
1403 | text that may contain whitespace or comments, and putting a line that says | |
1404 | @code{#NO_APP} after this text. This feature is mainly intend to support | |
1405 | @code{asm} statements in compilers whose output is otherwise free of comments | |
1406 | and whitespace. | |
93b45514 | 1407 | |
242d9c06 | 1408 | @node Whitespace |
93b45514 | 1409 | @section Whitespace |
66b818fb RP |
1410 | |
1411 | @cindex whitespace | |
93b45514 | 1412 | @dfn{Whitespace} is one or more blanks or tabs, in any order. |
7a4c8e5c RP |
1413 | Whitespace is used to separate symbols, and to make programs neater for |
1414 | people to read. Unless within character constants | |
1415 | (@pxref{Characters,,Character Constants}), any whitespace means the same | |
1416 | as exactly one space. | |
93b45514 | 1417 | |
242d9c06 | 1418 | @node Comments |
93b45514 | 1419 | @section Comments |
66b818fb RP |
1420 | |
1421 | @cindex comments | |
f009d0ab | 1422 | There are two ways of rendering comments to @code{@value{AS}}. In both |
93b45514 RP |
1423 | cases the comment is equivalent to one space. |
1424 | ||
d0281557 RP |
1425 | Anything from @samp{/*} through the next @samp{*/} is a comment. |
1426 | This means you may not nest these comments. | |
93b45514 | 1427 | |
d0281557 | 1428 | @smallexample |
93b45514 RP |
1429 | /* |
1430 | The only way to include a newline ('\n') in a comment | |
1431 | is to use this sort of comment. | |
1432 | */ | |
47342e8f | 1433 | |
93b45514 | 1434 | /* This sort of comment does not nest. */ |
d0281557 | 1435 | @end smallexample |
93b45514 | 1436 | |
66b818fb | 1437 | @cindex line comment character |
93b45514 | 1438 | Anything from the @dfn{line comment} character to the next newline |
47342e8f | 1439 | is considered a comment and is ignored. The line comment character is |
910d7df2 C |
1440 | @ifset A29K |
1441 | @samp{;} for the AMD 29K family; | |
1442 | @end ifset | |
99c4053d KR |
1443 | @ifset ARC |
1444 | @samp{;} on the ARC; | |
1445 | @end ifset | |
f009d0ab | 1446 | @ifset H8/300 |
9ebc250f | 1447 | @samp{;} for the H8/300 family; |
f009d0ab RP |
1448 | @end ifset |
1449 | @ifset H8/500 | |
1450 | @samp{!} for the H8/500 family; | |
1451 | @end ifset | |
9dcf8057 JL |
1452 | @ifset HPPA |
1453 | @samp{;} for the HPPA; | |
1454 | @end ifset | |
910d7df2 C |
1455 | @ifset I960 |
1456 | @samp{#} on the i960; | |
1457 | @end ifset | |
f009d0ab RP |
1458 | @ifset SH |
1459 | @samp{!} for the Hitachi SH; | |
1460 | @end ifset | |
910d7df2 C |
1461 | @ifset SPARC |
1462 | @samp{!} on the SPARC; | |
1463 | @end ifset | |
ee73be40 NC |
1464 | @ifset M32R |
1465 | @samp{#} on the m32r; | |
1466 | @end ifset | |
910d7df2 C |
1467 | @ifset M680X0 |
1468 | @samp{|} on the 680x0; | |
1469 | @end ifset | |
1470 | @ifset VAX | |
1471 | @samp{#} on the Vax; | |
1472 | @end ifset | |
f009d0ab | 1473 | @ifset Z8000 |
ba487f3a | 1474 | @samp{!} for the Z8000; |
f009d0ab | 1475 | @end ifset |
68eaa141 NC |
1476 | @ifset V850 |
1477 | @samp{#} on the V850; | |
1478 | @end ifset | |
f009d0ab | 1479 | see @ref{Machine Dependencies}. @refill |
9ebc250f | 1480 | @c FIXME What about i386, m88k, i860? |
09352a5d | 1481 | |
f009d0ab | 1482 | @ifset GENERIC |
b50e59fe | 1483 | On some machines there are two different line comment characters. One |
05a0e43b RP |
1484 | character only begins a comment if it is the first non-whitespace character on |
1485 | a line, while the other always begins a comment. | |
f009d0ab | 1486 | @end ifset |
93b45514 | 1487 | |
68eaa141 NC |
1488 | @ifset V850 |
1489 | The V850 assembler also supports a double dash as starting a comment that | |
1490 | extends to the end of the line. | |
1491 | ||
1492 | @samp{--}; | |
1493 | @end ifset | |
68eaa141 | 1494 | |
66b818fb RP |
1495 | @kindex # |
1496 | @cindex lines starting with @code{#} | |
1497 | @cindex logical line numbers | |
dd565f85 RP |
1498 | To be compatible with past assemblers, lines that begin with @samp{#} have a |
1499 | special interpretation. Following the @samp{#} should be an absolute | |
05a0e43b | 1500 | expression (@pxref{Expressions}): the logical line number of the @emph{next} |
dd565f85 RP |
1501 | line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a |
1502 | new logical file name. The rest of the line, if any, should be whitespace. | |
93b45514 RP |
1503 | |
1504 | If the first non-whitespace characters on the line are not numeric, | |
1505 | the line is ignored. (Just like a comment.) | |
dd565f85 | 1506 | |
d0281557 | 1507 | @smallexample |
93b45514 RP |
1508 | # This is an ordinary comment. |
1509 | # 42-6 "new_file_name" # New logical file name | |
1510 | # This is logical line # 36. | |
d0281557 | 1511 | @end smallexample |
93b45514 | 1512 | This feature is deprecated, and may disappear from future versions |
f009d0ab | 1513 | of @code{@value{AS}}. |
93b45514 | 1514 | |
242d9c06 | 1515 | @node Symbol Intro |
93b45514 | 1516 | @section Symbols |
66b818fb | 1517 | |
66b818fb | 1518 | @cindex characters used in symbols |
f009d0ab RP |
1519 | @ifclear SPECIAL-SYMS |
1520 | A @dfn{symbol} is one or more characters chosen from the set of all | |
1521 | letters (both upper and lower case), digits and the three characters | |
1522 | @samp{_.$}. | |
1523 | @end ifclear | |
1524 | @ifset SPECIAL-SYMS | |
1525 | @ifclear GENERIC | |
1526 | @ifset H8 | |
93b45514 | 1527 | A @dfn{symbol} is one or more characters chosen from the set of all |
f009d0ab RP |
1528 | letters (both upper and lower case), digits and the three characters |
1529 | @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in | |
1530 | symbol names.) | |
1531 | @end ifset | |
1532 | @end ifclear | |
1533 | @end ifset | |
1534 | @ifset GENERIC | |
24b1493d | 1535 | On most machines, you can also use @code{$} in symbol names; exceptions |
f009d0ab RP |
1536 | are noted in @ref{Machine Dependencies}. |
1537 | @end ifset | |
24b1493d | 1538 | No symbol may begin with a digit. Case is significant. |
b50e59fe RP |
1539 | There is no length limit: all characters are significant. Symbols are |
1540 | delimited by characters not in that set, or by the beginning of a file | |
1541 | (since the source program must end with a newline, the end of a file is | |
1542 | not a possible symbol delimiter). @xref{Symbols}. | |
66b818fb | 1543 | @cindex length of symbols |
93b45514 | 1544 | |
242d9c06 | 1545 | @node Statements |
93b45514 | 1546 | @section Statements |
66b818fb RP |
1547 | |
1548 | @cindex statements, structure of | |
1549 | @cindex line separator character | |
1550 | @cindex statement separator character | |
f009d0ab RP |
1551 | @ifclear GENERIC |
1552 | @ifclear abnormal-separator | |
d0281557 RP |
1553 | A @dfn{statement} ends at a newline character (@samp{\n}) or at a |
1554 | semicolon (@samp{;}). The newline or semicolon is considered part of | |
1555 | the preceding statement. Newlines and semicolons within character | |
05a0e43b | 1556 | constants are an exception: they do not end statements. |
f009d0ab RP |
1557 | @end ifclear |
1558 | @ifset abnormal-separator | |
1559 | @ifset A29K | |
d0281557 RP |
1560 | A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at'' |
1561 | sign (@samp{@@}). The newline or at sign is considered part of the | |
1562 | preceding statement. Newlines and at signs within character constants | |
05a0e43b | 1563 | are an exception: they do not end statements. |
f009d0ab | 1564 | @end ifset |
9dcf8057 JL |
1565 | @ifset HPPA |
1566 | A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation | |
1567 | point (@samp{!}). The newline or exclamation point is considered part of the | |
1568 | preceding statement. Newlines and exclamation points within character | |
05a0e43b | 1569 | constants are an exception: they do not end statements. |
9dcf8057 | 1570 | @end ifset |
f009d0ab RP |
1571 | @ifset H8 |
1572 | A @dfn{statement} ends at a newline character (@samp{\n}); or (for the | |
1573 | H8/300) a dollar sign (@samp{$}); or (for the | |
f009d0ab | 1574 | Hitachi-SH or the |
f009d0ab RP |
1575 | H8/500) a semicolon |
1576 | (@samp{;}). The newline or separator character is considered part of | |
1577 | the preceding statement. Newlines and separators within character | |
05a0e43b | 1578 | constants are an exception: they do not end statements. |
f009d0ab RP |
1579 | @end ifset |
1580 | @end ifset | |
1581 | @end ifclear | |
1582 | @ifset GENERIC | |
24b1493d RP |
1583 | A @dfn{statement} ends at a newline character (@samp{\n}) or line |
1584 | separator character. (The line separator is usually @samp{;}, unless | |
f009d0ab | 1585 | this conflicts with the comment character; @pxref{Machine Dependencies}.) The |
24b1493d RP |
1586 | newline or separator character is considered part of the preceding |
1587 | statement. Newlines and separators within character constants are an | |
05a0e43b | 1588 | exception: they do not end statements. |
f009d0ab | 1589 | @end ifset |
d0281557 | 1590 | |
66b818fb RP |
1591 | @cindex newline, required at file end |
1592 | @cindex EOF, newline must precede | |
93b45514 | 1593 | It is an error to end any statement with end-of-file: the last |
b50e59fe | 1594 | character of any input file should be a newline.@refill |
93b45514 | 1595 | |
66b818fb RP |
1596 | @cindex continuing statements |
1597 | @cindex multi-line statements | |
1598 | @cindex statement on multiple lines | |
93b45514 RP |
1599 | You may write a statement on more than one line if you put a |
1600 | backslash (@kbd{\}) immediately in front of any newlines within the | |
f009d0ab | 1601 | statement. When @code{@value{AS}} reads a backslashed newline both |
93b45514 RP |
1602 | characters are ignored. You can even put backslashed newlines in |
1603 | the middle of symbol names without changing the meaning of your | |
1604 | source program. | |
1605 | ||
47342e8f | 1606 | An empty statement is allowed, and may include whitespace. It is ignored. |
93b45514 | 1607 | |
66b818fb RP |
1608 | @cindex instructions and directives |
1609 | @cindex directives and instructions | |
b50e59fe | 1610 | @c "key symbol" is not used elsewhere in the document; seems pedantic to |
71dd3c40 | 1611 | @c @defn{} it in that case, as was done previously... doc@cygnus.com, |
d0281557 | 1612 | @c 13feb91. |
47342e8f | 1613 | A statement begins with zero or more labels, optionally followed by a |
b50e59fe | 1614 | key symbol which determines what kind of statement it is. The key |
93b45514 | 1615 | symbol determines the syntax of the rest of the statement. If the |
b50e59fe | 1616 | symbol begins with a dot @samp{.} then the statement is an assembler |
47342e8f RP |
1617 | directive: typically valid for any computer. If the symbol begins with |
1618 | a letter the statement is an assembly language @dfn{instruction}: it | |
05a0e43b | 1619 | assembles into a machine language instruction. |
f009d0ab | 1620 | @ifset GENERIC |
05a0e43b | 1621 | Different versions of @code{@value{AS}} for different computers |
d0281557 RP |
1622 | recognize different instructions. In fact, the same symbol may |
1623 | represent a different instruction in a different computer's assembly | |
1624 | language.@refill | |
f009d0ab | 1625 | @end ifset |
47342e8f | 1626 | |
66b818fb RP |
1627 | @cindex @code{:} (label) |
1628 | @cindex label (@code{:}) | |
d0281557 | 1629 | A label is a symbol immediately followed by a colon (@code{:}). |
47342e8f | 1630 | Whitespace before a label or after a colon is permitted, but you may not |
d0281557 | 1631 | have whitespace between a label's symbol and its colon. @xref{Labels}. |
93b45514 | 1632 | |
9dcf8057 JL |
1633 | @ifset HPPA |
1634 | For HPPA targets, labels need not be immediately followed by a colon, but | |
1635 | the definition of a label must begin in column zero. This also implies that | |
1636 | only one label may be defined on each line. | |
1637 | @end ifset | |
1638 | ||
d0281557 | 1639 | @smallexample |
93b45514 | 1640 | label: .directive followed by something |
24b1493d | 1641 | another_label: # This is an empty statement. |
93b45514 | 1642 | instruction operand_1, operand_2, @dots{} |
d0281557 | 1643 | @end smallexample |
93b45514 | 1644 | |
242d9c06 | 1645 | @node Constants |
93b45514 | 1646 | @section Constants |
66b818fb RP |
1647 | |
1648 | @cindex constants | |
93b45514 RP |
1649 | A constant is a number, written so that its value is known by |
1650 | inspection, without knowing any context. Like this: | |
f4335d56 | 1651 | @smallexample |
f009d0ab | 1652 | @group |
93b45514 RP |
1653 | .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. |
1654 | .ascii "Ring the bell\7" # A string constant. | |
1655 | .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. | |
1656 | .float 0f-314159265358979323846264338327\ | |
1657 | 95028841971.693993751E-40 # - pi, a flonum. | |
f009d0ab | 1658 | @end group |
f4335d56 | 1659 | @end smallexample |
93b45514 | 1660 | |
7a4c8e5c | 1661 | @menu |
ba487f3a RP |
1662 | * Characters:: Character Constants |
1663 | * Numbers:: Number Constants | |
7a4c8e5c RP |
1664 | @end menu |
1665 | ||
242d9c06 | 1666 | @node Characters |
93b45514 | 1667 | @subsection Character Constants |
66b818fb RP |
1668 | |
1669 | @cindex character constants | |
1670 | @cindex constants, character | |
47342e8f RP |
1671 | There are two kinds of character constants. A @dfn{character} stands |
1672 | for one character in one byte and its value may be used in | |
93b45514 | 1673 | numeric expressions. String constants (properly called string |
47342e8f | 1674 | @emph{literals}) are potentially many bytes and their values may not be |
93b45514 RP |
1675 | used in arithmetic expressions. |
1676 | ||
7a4c8e5c | 1677 | @menu |
ba487f3a RP |
1678 | * Strings:: Strings |
1679 | * Chars:: Characters | |
7a4c8e5c RP |
1680 | @end menu |
1681 | ||
242d9c06 | 1682 | @node Strings |
93b45514 | 1683 | @subsubsection Strings |
66b818fb RP |
1684 | |
1685 | @cindex string constants | |
1686 | @cindex constants, string | |
93b45514 | 1687 | A @dfn{string} is written between double-quotes. It may contain |
47342e8f | 1688 | double-quotes or null characters. The way to get special characters |
93b45514 | 1689 | into a string is to @dfn{escape} these characters: precede them with |
b50e59fe | 1690 | a backslash @samp{\} character. For example @samp{\\} represents |
93b45514 | 1691 | one backslash: the first @code{\} is an escape which tells |
f009d0ab RP |
1692 | @code{@value{AS}} to interpret the second character literally as a backslash |
1693 | (which prevents @code{@value{AS}} from recognizing the second @code{\} as an | |
93b45514 RP |
1694 | escape character). The complete list of escapes follows. |
1695 | ||
66b818fb RP |
1696 | @cindex escape codes, character |
1697 | @cindex character escape codes | |
93b45514 | 1698 | @table @kbd |
ba487f3a RP |
1699 | @c @item \a |
1700 | @c Mnemonic for ACKnowledge; for ASCII this is octal code 007. | |
66b818fb | 1701 | @c |
66b818fb RP |
1702 | @cindex @code{\b} (backspace character) |
1703 | @cindex backspace (@code{\b}) | |
71dd3c40 | 1704 | @item \b |
93b45514 | 1705 | Mnemonic for backspace; for ASCII this is octal code 010. |
66b818fb | 1706 | |
ba487f3a RP |
1707 | @c @item \e |
1708 | @c Mnemonic for EOText; for ASCII this is octal code 004. | |
66b818fb | 1709 | @c |
66b818fb RP |
1710 | @cindex @code{\f} (formfeed character) |
1711 | @cindex formfeed (@code{\f}) | |
71dd3c40 | 1712 | @item \f |
93b45514 | 1713 | Mnemonic for FormFeed; for ASCII this is octal code 014. |
66b818fb | 1714 | |
66b818fb RP |
1715 | @cindex @code{\n} (newline character) |
1716 | @cindex newline (@code{\n}) | |
71dd3c40 | 1717 | @item \n |
93b45514 | 1718 | Mnemonic for newline; for ASCII this is octal code 012. |
66b818fb | 1719 | |
ba487f3a RP |
1720 | @c @item \p |
1721 | @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}. | |
66b818fb | 1722 | @c |
66b818fb RP |
1723 | @cindex @code{\r} (carriage return character) |
1724 | @cindex carriage return (@code{\r}) | |
71dd3c40 | 1725 | @item \r |
93b45514 | 1726 | Mnemonic for carriage-Return; for ASCII this is octal code 015. |
66b818fb | 1727 | |
ba487f3a RP |
1728 | @c @item \s |
1729 | @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with | |
1730 | @c other assemblers. | |
66b818fb | 1731 | @c |
66b818fb RP |
1732 | @cindex @code{\t} (tab) |
1733 | @cindex tab (@code{\t}) | |
71dd3c40 | 1734 | @item \t |
93b45514 | 1735 | Mnemonic for horizontal Tab; for ASCII this is octal code 011. |
66b818fb | 1736 | |
ba487f3a RP |
1737 | @c @item \v |
1738 | @c Mnemonic for Vertical tab; for ASCII this is octal code 013. | |
1739 | @c @item \x @var{digit} @var{digit} @var{digit} | |
1740 | @c A hexadecimal character code. The numeric code is 3 hexadecimal digits. | |
66b818fb | 1741 | @c |
66b818fb RP |
1742 | @cindex @code{\@var{ddd}} (octal character code) |
1743 | @cindex octal character code (@code{\@var{ddd}}) | |
71dd3c40 | 1744 | @item \ @var{digit} @var{digit} @var{digit} |
93b45514 | 1745 | An octal character code. The numeric code is 3 octal digits. |
47342e8f RP |
1746 | For compatibility with other Unix systems, 8 and 9 are accepted as digits: |
1747 | for example, @code{\008} has the value 010, and @code{\009} the value 011. | |
66b818fb | 1748 | |
910d7df2 C |
1749 | @cindex @code{\@var{xd...}} (hex character code) |
1750 | @cindex hex character code (@code{\@var{xd...}}) | |
1751 | @item \@code{x} @var{hex-digits...} | |
1752 | A hex character code. All trailing hex digits are combined. Either upper or | |
1753 | lower case @code{x} works. | |
9dcf8057 | 1754 | |
66b818fb RP |
1755 | @cindex @code{\\} (@samp{\} character) |
1756 | @cindex backslash (@code{\\}) | |
71dd3c40 | 1757 | @item \\ |
93b45514 | 1758 | Represents one @samp{\} character. |
66b818fb | 1759 | |
ba487f3a RP |
1760 | @c @item \' |
1761 | @c Represents one @samp{'} (accent acute) character. | |
1762 | @c This is needed in single character literals | |
7a4c8e5c | 1763 | @c (@xref{Characters,,Character Constants}.) to represent |
ba487f3a | 1764 | @c a @samp{'}. |
66b818fb | 1765 | @c |
66b818fb RP |
1766 | @cindex @code{\"} (doublequote character) |
1767 | @cindex doublequote (@code{\"}) | |
71dd3c40 | 1768 | @item \" |
93b45514 RP |
1769 | Represents one @samp{"} character. Needed in strings to represent |
1770 | this character, because an unescaped @samp{"} would end the string. | |
66b818fb | 1771 | |
93b45514 | 1772 | @item \ @var{anything-else} |
05a0e43b | 1773 | Any other character when escaped by @kbd{\} gives a warning, but |
dd565f85 | 1774 | assembles as if the @samp{\} was not present. The idea is that if |
93b45514 | 1775 | you used an escape sequence you clearly didn't want the literal |
f009d0ab RP |
1776 | interpretation of the following character. However @code{@value{AS}} has no |
1777 | other interpretation, so @code{@value{AS}} knows it is giving you the wrong | |
93b45514 RP |
1778 | code and warns you of the fact. |
1779 | @end table | |
1780 | ||
1781 | Which characters are escapable, and what those escapes represent, | |
1782 | varies widely among assemblers. The current set is what we think | |
d0281557 | 1783 | the BSD 4.2 assembler recognizes, and is a subset of what most C |
05a0e43b | 1784 | compilers recognize. If you are in doubt, do not use an escape |
93b45514 RP |
1785 | sequence. |
1786 | ||
242d9c06 | 1787 | @node Chars |
93b45514 | 1788 | @subsubsection Characters |
66b818fb RP |
1789 | |
1790 | @cindex single character constant | |
1791 | @cindex character, single | |
1792 | @cindex constant, single character | |
93b45514 RP |
1793 | A single character may be written as a single quote immediately |
1794 | followed by that character. The same escapes apply to characters as | |
1795 | to strings. So if you want to write the character backslash, you | |
1796 | must write @kbd{'\\} where the first @code{\} escapes the second | |
b50e59fe | 1797 | @code{\}. As you can see, the quote is an acute accent, not a |
d0281557 | 1798 | grave accent. A newline |
f009d0ab RP |
1799 | @ifclear GENERIC |
1800 | @ifclear abnormal-separator | |
09352a5d | 1801 | (or semicolon @samp{;}) |
f009d0ab RP |
1802 | @end ifclear |
1803 | @ifset abnormal-separator | |
1804 | @ifset A29K | |
b50e59fe | 1805 | (or at sign @samp{@@}) |
f009d0ab RP |
1806 | @end ifset |
1807 | @ifset H8 | |
1808 | (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the | |
f009d0ab | 1809 | Hitachi SH or |
f009d0ab RP |
1810 | H8/500) |
1811 | @end ifset | |
1812 | @end ifset | |
1813 | @end ifclear | |
d0281557 RP |
1814 | immediately following an acute accent is taken as a literal character |
1815 | and does not count as the end of a statement. The value of a character | |
93b45514 | 1816 | constant in a numeric expression is the machine's byte-wide code for |
f009d0ab | 1817 | that character. @code{@value{AS}} assumes your character code is ASCII: |
d0281557 | 1818 | @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill |
93b45514 | 1819 | |
242d9c06 | 1820 | @node Numbers |
93b45514 | 1821 | @subsection Number Constants |
66b818fb RP |
1822 | |
1823 | @cindex constants, number | |
1824 | @cindex number constants | |
f009d0ab | 1825 | @code{@value{AS}} distinguishes three kinds of numbers according to how they |
47342e8f RP |
1826 | are stored in the target machine. @emph{Integers} are numbers that |
1827 | would fit into an @code{int} in the C language. @emph{Bignums} are | |
d0281557 | 1828 | integers, but they are stored in more than 32 bits. @emph{Flonums} |
93b45514 RP |
1829 | are floating point numbers, described below. |
1830 | ||
7a4c8e5c | 1831 | @menu |
ba487f3a RP |
1832 | * Integers:: Integers |
1833 | * Bignums:: Bignums | |
1834 | * Flonums:: Flonums | |
f009d0ab RP |
1835 | @ifclear GENERIC |
1836 | @ifset I960 | |
ba487f3a | 1837 | * Bit Fields:: Bit Fields |
f009d0ab RP |
1838 | @end ifset |
1839 | @end ifclear | |
7a4c8e5c RP |
1840 | @end menu |
1841 | ||
242d9c06 | 1842 | @node Integers |
93b45514 | 1843 | @subsubsection Integers |
66b818fb RP |
1844 | @cindex integers |
1845 | @cindex constants, integer | |
1846 | ||
1847 | @cindex binary integers | |
1848 | @cindex integers, binary | |
b50e59fe RP |
1849 | A binary integer is @samp{0b} or @samp{0B} followed by zero or more of |
1850 | the binary digits @samp{01}. | |
1851 | ||
66b818fb RP |
1852 | @cindex octal integers |
1853 | @cindex integers, octal | |
93b45514 RP |
1854 | An octal integer is @samp{0} followed by zero or more of the octal |
1855 | digits (@samp{01234567}). | |
1856 | ||
66b818fb RP |
1857 | @cindex decimal integers |
1858 | @cindex integers, decimal | |
93b45514 RP |
1859 | A decimal integer starts with a non-zero digit followed by zero or |
1860 | more digits (@samp{0123456789}). | |
1861 | ||
66b818fb RP |
1862 | @cindex hexadecimal integers |
1863 | @cindex integers, hexadecimal | |
93b45514 RP |
1864 | A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or |
1865 | more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}. | |
1866 | ||
47342e8f | 1867 | Integers have the usual values. To denote a negative integer, use |
b50e59fe | 1868 | the prefix operator @samp{-} discussed under expressions |
7a4c8e5c | 1869 | (@pxref{Prefix Ops,,Prefix Operators}). |
93b45514 | 1870 | |
242d9c06 | 1871 | @node Bignums |
93b45514 | 1872 | @subsubsection Bignums |
66b818fb RP |
1873 | |
1874 | @cindex bignums | |
1875 | @cindex constants, bignum | |
93b45514 RP |
1876 | A @dfn{bignum} has the same syntax and semantics as an integer |
1877 | except that the number (or its negative) takes more than 32 bits to | |
1878 | represent in binary. The distinction is made because in some places | |
1879 | integers are permitted while bignums are not. | |
1880 | ||
242d9c06 | 1881 | @node Flonums |
93b45514 | 1882 | @subsubsection Flonums |
66b818fb RP |
1883 | @cindex flonums |
1884 | @cindex floating point numbers | |
1885 | @cindex constants, floating point | |
1886 | ||
1887 | @cindex precision, floating point | |
b50e59fe | 1888 | A @dfn{flonum} represents a floating point number. The translation is |
66b818fb | 1889 | indirect: a decimal floating point number from the text is converted by |
f009d0ab | 1890 | @code{@value{AS}} to a generic binary floating point number of more than |
b50e59fe RP |
1891 | sufficient precision. This generic floating point number is converted |
1892 | to a particular computer's floating point format (or formats) by a | |
f009d0ab | 1893 | portion of @code{@value{AS}} specialized to that computer. |
93b45514 RP |
1894 | |
1895 | A flonum is written by writing (in order) | |
1896 | @itemize @bullet | |
1897 | @item | |
1898 | The digit @samp{0}. | |
9dcf8057 | 1899 | @ifset HPPA |
05a0e43b | 1900 | (@samp{0} is optional on the HPPA.) |
9dcf8057 | 1901 | @end ifset |
f009d0ab | 1902 | |
93b45514 | 1903 | @item |
f009d0ab RP |
1904 | A letter, to tell @code{@value{AS}} the rest of the number is a flonum. |
1905 | @ifset GENERIC | |
66b818fb | 1906 | @kbd{e} is recommended. Case is not important. |
0b5b143a RP |
1907 | @ignore |
1908 | @c FIXME: verify if flonum syntax really this vague for most cases | |
05a0e43b RP |
1909 | (Any otherwise illegal letter works here, but that might be changed. Vax BSD |
1910 | 4.2 assembler seems to allow any of @samp{defghDEFGH}.) | |
0b5b143a | 1911 | @end ignore |
f009d0ab RP |
1912 | |
1913 | On the H8/300, H8/500, | |
f009d0ab | 1914 | Hitachi SH, |
f009d0ab RP |
1915 | and AMD 29K architectures, the letter must be |
1916 | one of the letters @samp{DFPRSX} (in upper or lower case). | |
1917 | ||
3ffb03b1 | 1918 | On the ARC, the letter must be one of the letters @samp{DFRS} |
99c4053d | 1919 | (in upper or lower case). |
99c4053d | 1920 | |
f009d0ab RP |
1921 | On the Intel 960 architecture, the letter must be |
1922 | one of the letters @samp{DFT} (in upper or lower case). | |
9dcf8057 JL |
1923 | |
1924 | On the HPPA architecture, the letter must be @samp{E} (upper case only). | |
f009d0ab RP |
1925 | @end ifset |
1926 | @ifclear GENERIC | |
1927 | @ifset A29K | |
66b818fb | 1928 | One of the letters @samp{DFPRSX} (in upper or lower case). |
f009d0ab | 1929 | @end ifset |
99c4053d KR |
1930 | @ifset ARC |
1931 | One of the letters @samp{DFRS} (in upper or lower case). | |
1932 | @end ifset | |
f009d0ab RP |
1933 | @ifset H8 |
1934 | One of the letters @samp{DFPRSX} (in upper or lower case). | |
1935 | @end ifset | |
9dcf8057 | 1936 | @ifset HPPA |
05a0e43b | 1937 | The letter @samp{E} (upper case only). |
9dcf8057 | 1938 | @end ifset |
910d7df2 C |
1939 | @ifset I960 |
1940 | One of the letters @samp{DFT} (in upper or lower case). | |
1941 | @end ifset | |
f009d0ab RP |
1942 | @end ifclear |
1943 | ||
93b45514 RP |
1944 | @item |
1945 | An optional sign: either @samp{+} or @samp{-}. | |
f009d0ab | 1946 | |
93b45514 | 1947 | @item |
47342e8f | 1948 | An optional @dfn{integer part}: zero or more decimal digits. |
f009d0ab | 1949 | |
93b45514 | 1950 | @item |
66b818fb | 1951 | An optional @dfn{fractional part}: @samp{.} followed by zero |
93b45514 | 1952 | or more decimal digits. |
f009d0ab | 1953 | |
93b45514 RP |
1954 | @item |
1955 | An optional exponent, consisting of: | |
f009d0ab | 1956 | |
93b45514 RP |
1957 | @itemize @bullet |
1958 | @item | |
b50e59fe | 1959 | An @samp{E} or @samp{e}. |
d0281557 RP |
1960 | @c I can't find a config where "EXP_CHARS" is other than 'eE', but in |
1961 | @c principle this can perfectly well be different on different targets. | |
93b45514 RP |
1962 | @item |
1963 | Optional sign: either @samp{+} or @samp{-}. | |
1964 | @item | |
1965 | One or more decimal digits. | |
1966 | @end itemize | |
f009d0ab | 1967 | |
93b45514 RP |
1968 | @end itemize |
1969 | ||
66b818fb | 1970 | At least one of the integer part or the fractional part must be |
47342e8f | 1971 | present. The floating point number has the usual base-10 value. |
93b45514 | 1972 | |
f009d0ab | 1973 | @code{@value{AS}} does all processing using integers. Flonums are computed |
47342e8f | 1974 | independently of any floating point hardware in the computer running |
f009d0ab | 1975 | @code{@value{AS}}. |
d0281557 | 1976 | |
f009d0ab RP |
1977 | @ifclear GENERIC |
1978 | @ifset I960 | |
d0281557 RP |
1979 | @c Bit fields are written as a general facility but are also controlled |
1980 | @c by a conditional-compilation flag---which is as of now (21mar91) | |
1981 | @c turned on only by the i960 config of GAS. | |
242d9c06 | 1982 | @node Bit Fields |
d0281557 | 1983 | @subsubsection Bit Fields |
66b818fb RP |
1984 | |
1985 | @cindex bit fields | |
1986 | @cindex constants, bit field | |
d0281557 RP |
1987 | You can also define numeric constants as @dfn{bit fields}. |
1988 | specify two numbers separated by a colon--- | |
1989 | @example | |
1990 | @var{mask}:@var{value} | |
1991 | @end example | |
1992 | @noindent | |
05a0e43b RP |
1993 | @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and |
1994 | @var{value}. | |
d0281557 RP |
1995 | |
1996 | The resulting number is then packed | |
f009d0ab | 1997 | @ifset GENERIC |
7a4c8e5c | 1998 | @c this conditional paren in case bit fields turned on elsewhere than 960 |
d0281557 | 1999 | (in host-dependent byte order) |
f009d0ab | 2000 | @end ifset |
d0281557 RP |
2001 | into a field whose width depends on which assembler directive has the |
2002 | bit-field as its argument. Overflow (a result from the bitwise and | |
2003 | requiring more binary digits to represent) is not an error; instead, | |
2004 | more constants are generated, of the specified width, beginning with the | |
2005 | least significant digits.@refill | |
2006 | ||
2007 | The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long}, | |
2008 | @code{.short}, and @code{.word} accept bit-field arguments. | |
f009d0ab RP |
2009 | @end ifset |
2010 | @end ifclear | |
93b45514 | 2011 | |
242d9c06 | 2012 | @node Sections |
24b1493d | 2013 | @chapter Sections and Relocation |
66b818fb RP |
2014 | @cindex sections |
2015 | @cindex relocation | |
d0281557 | 2016 | |
7a4c8e5c | 2017 | @menu |
ba487f3a | 2018 | * Secs Background:: Background |
3ffb03b1 DE |
2019 | * Ld Sections:: Linker Sections |
2020 | * As Sections:: Assembler Internal Sections | |
ba487f3a RP |
2021 | * Sub-Sections:: Sub-Sections |
2022 | * bss:: bss Section | |
7a4c8e5c RP |
2023 | @end menu |
2024 | ||
242d9c06 | 2025 | @node Secs Background |
b50e59fe | 2026 | @section Background |
66b818fb | 2027 | |
24b1493d | 2028 | Roughly, a section is a range of addresses, with no gaps; all data |
d0281557 | 2029 | ``in'' those addresses is treated the same for some particular purpose. |
24b1493d | 2030 | For example there may be a ``read only'' section. |
93b45514 | 2031 | |
66b818fb RP |
2032 | @cindex linker, and assembler |
2033 | @cindex assembler, and linker | |
f009d0ab RP |
2034 | The linker @code{@value{LD}} reads many object files (partial programs) and |
2035 | combines their contents to form a runnable program. When @code{@value{AS}} | |
05a0e43b RP |
2036 | emits an object file, the partial program is assumed to start at address 0. |
2037 | @code{@value{LD}} assigns the final addresses for the partial program, so that | |
2038 | different partial programs do not overlap. This is actually an | |
2039 | oversimplification, but it suffices to explain how @code{@value{AS}} uses | |
2040 | sections. | |
93b45514 | 2041 | |
f009d0ab | 2042 | @code{@value{LD}} moves blocks of bytes of your program to their run-time |
93b45514 | 2043 | addresses. These blocks slide to their run-time addresses as rigid |
47342e8f | 2044 | units; their length does not change and neither does the order of bytes |
24b1493d RP |
2045 | within them. Such a rigid unit is called a @emph{section}. Assigning |
2046 | run-time addresses to sections is called @dfn{relocation}. It includes | |
47342e8f | 2047 | the task of adjusting mentions of object-file addresses so they refer to |
d0281557 | 2048 | the proper run-time addresses. |
f009d0ab RP |
2049 | @ifset H8 |
2050 | For the H8/300 and H8/500, | |
f009d0ab | 2051 | and for the Hitachi SH, |
f009d0ab RP |
2052 | @code{@value{AS}} pads sections if needed to |
2053 | ensure they end on a word (sixteen bit) boundary. | |
2054 | @end ifset | |
2055 | ||
3ffb03b1 | 2056 | @cindex standard assembler sections |
f009d0ab | 2057 | An object file written by @code{@value{AS}} has at least three sections, any |
24b1493d | 2058 | of which may be empty. These are named @dfn{text}, @dfn{data} and |
f009d0ab | 2059 | @dfn{bss} sections. |
93b45514 | 2060 | |
f009d0ab RP |
2061 | @ifset COFF |
2062 | @ifset GENERIC | |
2063 | When it generates COFF output, | |
2064 | @end ifset | |
2065 | @code{@value{AS}} can also generate whatever other named sections you specify | |
24b1493d | 2066 | using the @samp{.section} directive (@pxref{Section,,@code{.section}}). |
05a0e43b RP |
2067 | If you do not use any directives that place output in the @samp{.text} |
2068 | or @samp{.data} sections, these sections still exist, but are empty. | |
f009d0ab | 2069 | @end ifset |
d0281557 | 2070 | |
9dcf8057 JL |
2071 | @ifset HPPA |
2072 | @ifset GENERIC | |
2073 | When @code{@value{AS}} generates SOM or ELF output for the HPPA, | |
2074 | @end ifset | |
2075 | @code{@value{AS}} can also generate whatever other named sections you | |
2076 | specify using the @samp{.space} and @samp{.subspace} directives. See | |
2077 | @cite{HP9000 Series 800 Assembly Language Reference Manual} | |
2078 | (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace} | |
2079 | assembler directives. | |
2080 | ||
2081 | @ifset SOM | |
2082 | Additionally, @code{@value{AS}} uses different names for the standard | |
2083 | text, data, and bss sections when generating SOM output. Program text | |
2084 | is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and | |
2085 | BSS into @samp{$BSS$}. | |
2086 | @end ifset | |
2087 | @end ifset | |
2088 | ||
24b1493d RP |
2089 | Within the object file, the text section starts at address @code{0}, the |
2090 | data section follows, and the bss section follows the data section. | |
d0281557 | 2091 | |
9dcf8057 JL |
2092 | @ifset HPPA |
2093 | When generating either SOM or ELF output files on the HPPA, the text | |
2094 | section starts at address @code{0}, the data section at address | |
2095 | @code{0x4000000}, and the bss section follows the data section. | |
2096 | @end ifset | |
2097 | ||
05a0e43b | 2098 | To let @code{@value{LD}} know which data changes when the sections are |
f009d0ab | 2099 | relocated, and how to change that data, @code{@value{AS}} also writes to the |
93b45514 | 2100 | object file details of the relocation needed. To perform relocation |
f009d0ab | 2101 | @code{@value{LD}} must know, each time an address in the object |
47342e8f | 2102 | file is mentioned: |
93b45514 RP |
2103 | @itemize @bullet |
2104 | @item | |
47342e8f RP |
2105 | Where in the object file is the beginning of this reference to |
2106 | an address? | |
93b45514 | 2107 | @item |
47342e8f | 2108 | How long (in bytes) is this reference? |
93b45514 | 2109 | @item |
24b1493d | 2110 | Which section does the address refer to? What is the numeric value of |
b50e59fe | 2111 | @display |
24b1493d | 2112 | (@var{address}) @minus{} (@var{start-address of section})? |
b50e59fe | 2113 | @end display |
93b45514 | 2114 | @item |
b50e59fe | 2115 | Is the reference to an address ``Program-Counter relative''? |
93b45514 RP |
2116 | @end itemize |
2117 | ||
66b818fb RP |
2118 | @cindex addresses, format of |
2119 | @cindex section-relative addressing | |
f009d0ab | 2120 | In fact, every address @code{@value{AS}} ever uses is expressed as |
d0281557 | 2121 | @display |
24b1493d | 2122 | (@var{section}) + (@var{offset into section}) |
d0281557 RP |
2123 | @end display |
2124 | @noindent | |
65fbb2d7 RP |
2125 | Further, most expressions @code{@value{AS}} computes have this section-relative |
2126 | nature. | |
2127 | @ifset SOM | |
2128 | (For some object formats, such as SOM for the HPPA, some expressions are | |
2129 | symbol-relative instead.) | |
2130 | @end ifset | |
dd565f85 RP |
2131 | |
2132 | In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset | |
2133 | @var{N} into section @var{secname}.'' | |
24b1493d RP |
2134 | |
2135 | Apart from text, data and bss sections you need to know about the | |
f009d0ab | 2136 | @dfn{absolute} section. When @code{@value{LD}} mixes partial programs, |
66b818fb | 2137 | addresses in the absolute section remain unchanged. For example, address |
05a0e43b RP |
2138 | @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by |
2139 | @code{@value{LD}}. Although the linker never arranges two partial programs' | |
2140 | data sections with overlapping addresses after linking, @emph{by definition} | |
2141 | their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one | |
2142 | part of a program is always the same address when the program is running as | |
2143 | address @code{@{absolute@ 239@}} in any other part of the program. | |
47342e8f | 2144 | |
24b1493d RP |
2145 | The idea of sections is extended to the @dfn{undefined} section. Any |
2146 | address whose section is unknown at assembly time is by definition | |
05a0e43b | 2147 | rendered @{undefined @var{U}@}---where @var{U} is filled in later. |
47342e8f | 2148 | Since numbers are always defined, the only way to generate an undefined |
93b45514 RP |
2149 | address is to mention an undefined symbol. A reference to a named |
2150 | common block would be such a symbol: its value is unknown at assembly | |
24b1493d | 2151 | time so it has section @emph{undefined}. |
93b45514 | 2152 | |
24b1493d | 2153 | By analogy the word @emph{section} is used to describe groups of sections in |
f009d0ab | 2154 | the linked program. @code{@value{LD}} puts all partial programs' text |
24b1493d RP |
2155 | sections in contiguous addresses in the linked program. It is |
2156 | customary to refer to the @emph{text section} of a program, meaning all | |
05a0e43b | 2157 | the addresses of all partial programs' text sections. Likewise for |
24b1493d | 2158 | data and bss sections. |
93b45514 | 2159 | |
f009d0ab RP |
2160 | Some sections are manipulated by @code{@value{LD}}; others are invented for |
2161 | use of @code{@value{AS}} and have no meaning except during assembly. | |
47342e8f | 2162 | |
f009d0ab | 2163 | @node Ld Sections |
3ffb03b1 | 2164 | @section Linker Sections |
f009d0ab | 2165 | @code{@value{LD}} deals with just four kinds of sections, summarized below. |
b50e59fe RP |
2166 | |
2167 | @table @strong | |
47342e8f | 2168 | |
f009d0ab | 2169 | @ifset COFF |
66b818fb RP |
2170 | @cindex named sections |
2171 | @cindex sections, named | |
24b1493d | 2172 | @item named sections |
f009d0ab RP |
2173 | @end ifset |
2174 | @ifset aout-bout | |
66b818fb RP |
2175 | @cindex text section |
2176 | @cindex data section | |
9dcf8057 | 2177 | @itemx text section |
24b1493d | 2178 | @itemx data section |
f009d0ab RP |
2179 | @end ifset |
2180 | These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as | |
24b1493d | 2181 | separate but equal sections. Anything you can say of one section is |
f009d0ab RP |
2182 | true another. |
2183 | @ifset aout-bout | |
24b1493d RP |
2184 | When the program is running, however, it is |
2185 | customary for the text section to be unalterable. The | |
05a0e43b | 2186 | text section is often shared among processes: it contains |
24b1493d | 2187 | instructions, constants and the like. The data section of a running |
b50e59fe | 2188 | program is usually alterable: for example, C variables would be stored |
24b1493d | 2189 | in the data section. |
f009d0ab | 2190 | @end ifset |
47342e8f | 2191 | |
66b818fb | 2192 | @cindex bss section |
24b1493d RP |
2193 | @item bss section |
2194 | This section contains zeroed bytes when your program begins running. It | |
47342e8f | 2195 | is used to hold unitialized variables or common storage. The length of |
24b1493d | 2196 | each partial program's bss section is important, but because it starts |
47342e8f | 2197 | out containing zeroed bytes there is no need to store explicit zero |
24b1493d | 2198 | bytes in the object file. The bss section was invented to eliminate |
d0281557 | 2199 | those explicit zeros from object files. |
47342e8f | 2200 | |
66b818fb | 2201 | @cindex absolute section |
24b1493d RP |
2202 | @item absolute section |
2203 | Address 0 of this section is always ``relocated'' to runtime address 0. | |
f009d0ab | 2204 | This is useful if you want to refer to an address that @code{@value{LD}} must |
47342e8f | 2205 | not change when relocating. In this sense we speak of absolute |
05a0e43b | 2206 | addresses being ``unrelocatable'': they do not change during relocation. |
47342e8f | 2207 | |
66b818fb | 2208 | @cindex undefined section |
24b1493d RP |
2209 | @item undefined section |
2210 | This ``section'' is a catch-all for address references to objects not in | |
2211 | the preceding sections. | |
47342e8f | 2212 | @c FIXME: ref to some other doc on obj-file formats could go here. |
93b45514 | 2213 | @end table |
47342e8f | 2214 | |
66b818fb | 2215 | @cindex relocation example |
f009d0ab RP |
2216 | An idealized example of three relocatable sections follows. |
2217 | @ifset COFF | |
66b818fb | 2218 | The example uses the traditional section names @samp{.text} and @samp{.data}. |
f009d0ab | 2219 | @end ifset |
24b1493d | 2220 | Memory addresses are on the horizontal axis. |
93b45514 | 2221 | |
7d7ecbdd | 2222 | @c TEXI2ROFF-KILL |
b50e59fe | 2223 | @ifinfo |
7d7ecbdd | 2224 | @c END TEXI2ROFF-KILL |
d0281557 | 2225 | @smallexample |
93b45514 RP |
2226 | +-----+----+--+ |
2227 | partial program # 1: |ttttt|dddd|00| | |
2228 | +-----+----+--+ | |
2229 | ||
2230 | text data bss | |
2231 | seg. seg. seg. | |
2232 | ||
2233 | +---+---+---+ | |
2234 | partial program # 2: |TTT|DDD|000| | |
2235 | +---+---+---+ | |
2236 | ||
2237 | +--+---+-----+--+----+---+-----+~~ | |
2238 | linked program: | |TTT|ttttt| |dddd|DDD|00000| | |
2239 | +--+---+-----+--+----+---+-----+~~ | |
2240 | ||
2241 | addresses: 0 @dots{} | |
d0281557 | 2242 | @end smallexample |
7d7ecbdd | 2243 | @c TEXI2ROFF-KILL |
b50e59fe | 2244 | @end ifinfo |
8babef85 | 2245 | @need 5000 |
b50e59fe | 2246 | @tex |
d0281557 | 2247 | |
66b818fb | 2248 | \line{\it Partial program \#1: \hfil} |
d0281557 RP |
2249 | \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
2250 | \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil} | |
2251 | ||
66b818fb | 2252 | \line{\it Partial program \#2: \hfil} |
d0281557 RP |
2253 | \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil} |
2254 | \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil} | |
2255 | ||
66b818fb | 2256 | \line{\it linked program: \hfil} |
d0281557 RP |
2257 | \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil} |
2258 | \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt | |
b50e59fe | 2259 | ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt |
d0281557 RP |
2260 | DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil} |
2261 | ||
66b818fb | 2262 | \line{\it addresses: \hfil} |
d0281557 RP |
2263 | \line{0\dots\hfil} |
2264 | ||
b50e59fe | 2265 | @end tex |
7d7ecbdd | 2266 | @c END TEXI2ROFF-KILL |
93b45514 | 2267 | |
f009d0ab | 2268 | @node As Sections |
3ffb03b1 | 2269 | @section Assembler Internal Sections |
66b818fb | 2270 | |
3ffb03b1 | 2271 | @cindex internal assembler sections |
66b818fb | 2272 | @cindex sections in messages, internal |
f009d0ab | 2273 | These sections are meant only for the internal use of @code{@value{AS}}. They |
05a0e43b | 2274 | have no meaning at run-time. You do not really need to know about these |
f009d0ab | 2275 | sections for most purposes; but they can be mentioned in @code{@value{AS}} |
24b1493d | 2276 | warning messages, so it might be helpful to have an idea of their |
f009d0ab | 2277 | meanings to @code{@value{AS}}. These sections are used to permit the |
24b1493d RP |
2278 | value of every expression in your assembly language program to be a |
2279 | section-relative address. | |
93b45514 | 2280 | |
d0281557 | 2281 | @table @b |
66b818fb | 2282 | @cindex assembler internal logic error |
71dd3c40 | 2283 | @item ASSEMBLER-INTERNAL-LOGIC-ERROR! |
24b1493d RP |
2284 | An internal assembler logic error has been found. This means there is a |
2285 | bug in the assembler. | |
2286 | ||
9dcf8057 | 2287 | @cindex expr (internal section) |
71dd3c40 | 2288 | @item expr section |
9dcf8057 JL |
2289 | The assembler stores complex expression internally as combinations of |
2290 | symbols. When it needs to represent an expression as a symbol, it puts | |
2291 | it in the expr section. | |
24b1493d RP |
2292 | @c FIXME item debug |
2293 | @c FIXME item transfer[t] vector preload | |
2294 | @c FIXME item transfer[t] vector postload | |
2295 | @c FIXME item register | |
93b45514 RP |
2296 | @end table |
2297 | ||
242d9c06 | 2298 | @node Sub-Sections |
24b1493d | 2299 | @section Sub-Sections |
66b818fb RP |
2300 | |
2301 | @cindex numbered subsections | |
2302 | @cindex grouping data | |
f009d0ab | 2303 | @ifset aout-bout |
24b1493d | 2304 | Assembled bytes |
f009d0ab | 2305 | @ifset COFF |
24b1493d | 2306 | conventionally |
f009d0ab RP |
2307 | @end ifset |
2308 | fall into two sections: text and data. | |
2309 | @end ifset | |
66b818fb | 2310 | You may have separate groups of |
f009d0ab | 2311 | @ifset GENERIC |
66b818fb | 2312 | data in named sections |
f009d0ab RP |
2313 | @end ifset |
2314 | @ifclear GENERIC | |
2315 | @ifclear aout-bout | |
2316 | data in named sections | |
2317 | @end ifclear | |
2318 | @ifset aout-bout | |
2319 | text or data | |
2320 | @end ifset | |
2321 | @end ifclear | |
05a0e43b RP |
2322 | that you want to end up near to each other in the object file, even though they |
2323 | are not contiguous in the assembler source. @code{@value{AS}} allows you to | |
2324 | use @dfn{subsections} for this purpose. Within each section, there can be | |
2325 | numbered subsections with values from 0 to 8192. Objects assembled into the | |
2326 | same subsection go into the object file together with other objects in the same | |
2327 | subsection. For example, a compiler might want to store constants in the text | |
2328 | section, but might not want to have them interspersed with the program being | |
2329 | assembled. In this case, the compiler could issue a @samp{.text 0} before each | |
2330 | section of code being output, and a @samp{.text 1} before each group of | |
2331 | constants being output. | |
2332 | ||
2333 | Subsections are optional. If you do not use subsections, everything | |
2334 | goes in subsection number zero. | |
93b45514 | 2335 | |
f009d0ab | 2336 | @ifset GENERIC |
24b1493d RP |
2337 | Each subsection is zero-padded up to a multiple of four bytes. |
2338 | (Subsections may be padded a different amount on different flavors | |
f009d0ab RP |
2339 | of @code{@value{AS}}.) |
2340 | @end ifset | |
2341 | @ifclear GENERIC | |
2342 | @ifset H8 | |
2343 | On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word | |
66b818fb | 2344 | boundary (two bytes). |
f009d0ab | 2345 | The same is true on the Hitachi SH. |
f009d0ab RP |
2346 | @end ifset |
2347 | @ifset I960 | |
24b1493d | 2348 | @c FIXME section padding (alignment)? |
d0281557 RP |
2349 | @c Rich Pixley says padding here depends on target obj code format; that |
2350 | @c doesn't seem particularly useful to say without further elaboration, | |
2351 | @c so for now I say nothing about it. If this is a generic BFD issue, | |
2352 | @c these paragraphs might need to vanish from this manual, and be | |
2353 | @c discussed in BFD chapter of binutils (or some such). | |
f009d0ab RP |
2354 | @end ifset |
2355 | @ifset A29K | |
66b818fb | 2356 | On the AMD 29K family, no particular padding is added to section or |
f009d0ab RP |
2357 | subsection sizes; @value{AS} forces no alignment on this platform. |
2358 | @end ifset | |
2359 | @end ifclear | |
66b818fb | 2360 | |
24b1493d | 2361 | Subsections appear in your object file in numeric order, lowest numbered |
b50e59fe | 2362 | to highest. (All this to be compatible with other people's assemblers.) |
f009d0ab | 2363 | The object file contains no representation of subsections; @code{@value{LD}} and |
05a0e43b | 2364 | other programs that manipulate object files see no trace of them. |
24b1493d RP |
2365 | They just see all your text subsections as a text section, and all your |
2366 | data subsections as a data section. | |
93b45514 | 2367 | |
24b1493d | 2368 | To specify which subsection you want subsequent statements assembled |
66b818fb RP |
2369 | into, use a numeric argument to specify it, in a @samp{.text |
2370 | @var{expression}} or a @samp{.data @var{expression}} statement. | |
f009d0ab RP |
2371 | @ifset COFF |
2372 | @ifset GENERIC | |
2373 | When generating COFF output, you | |
2374 | @end ifset | |
2375 | @ifclear GENERIC | |
66b818fb | 2376 | You |
f009d0ab | 2377 | @end ifclear |
66b818fb RP |
2378 | can also use an extra subsection |
2379 | argument with arbitrary named sections: @samp{.section @var{name}, | |
2380 | @var{expression}}. | |
f009d0ab | 2381 | @end ifset |
66b818fb RP |
2382 | @var{Expression} should be an absolute expression. |
2383 | (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0} | |
2384 | is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly | |
2385 | begins in @code{text 0}. For instance: | |
d0281557 | 2386 | @smallexample |
24b1493d RP |
2387 | .text 0 # The default subsection is text 0 anyway. |
2388 | .ascii "This lives in the first text subsection. *" | |
93b45514 | 2389 | .text 1 |
24b1493d | 2390 | .ascii "But this lives in the second text subsection." |
93b45514 | 2391 | .data 0 |
24b1493d RP |
2392 | .ascii "This lives in the data section," |
2393 | .ascii "in the first data subsection." | |
93b45514 | 2394 | .text 0 |
24b1493d | 2395 | .ascii "This lives in the first text section," |
93b45514 | 2396 | .ascii "immediately following the asterisk (*)." |
d0281557 | 2397 | @end smallexample |
93b45514 | 2398 | |
05a0e43b RP |
2399 | Each section has a @dfn{location counter} incremented by one for every byte |
2400 | assembled into that section. Because subsections are merely a convenience | |
2401 | restricted to @code{@value{AS}} there is no concept of a subsection location | |
2402 | counter. There is no way to directly manipulate a location counter---but the | |
2403 | @code{.align} directive changes it, and any label definition captures its | |
2404 | current value. The location counter of the section where statements are being | |
2405 | assembled is said to be the @dfn{active} location counter. | |
93b45514 | 2406 | |
242d9c06 | 2407 | @node bss |
24b1493d | 2408 | @section bss Section |
66b818fb RP |
2409 | |
2410 | @cindex bss section | |
2411 | @cindex common variable storage | |
24b1493d RP |
2412 | The bss section is used for local common variable storage. |
2413 | You may allocate address space in the bss section, but you may | |
93b45514 | 2414 | not dictate data to load into it before your program executes. When |
b50e59fe | 2415 | your program starts running, all the contents of the bss |
24b1493d | 2416 | section are zeroed bytes. |
93b45514 | 2417 | |
35cfacf0 ILT |
2418 | The @code{.lcomm} pseudo-op defines a symbol in the bss section; see |
2419 | @ref{Lcomm,,@code{.lcomm}}. | |
2420 | ||
2421 | The @code{.comm} pseudo-op may be used to declare a common symbol, which is | |
2422 | another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}. | |
2423 | ||
2424 | @ifset GENERIC | |
2425 | When assembling for a target which supports multiple sections, such as ELF or | |
2426 | COFF, you may switch into the @code{.bss} section and define symbols as usual; | |
2427 | see @ref{Section,,@code{.section}}. You may only assemble zero values into the | |
2428 | section. Typically the section will only contain symbol definitions and | |
2429 | @code{.skip} directives (@pxref{Skip,,@code{.skip}}). | |
2430 | @end ifset | |
93b45514 | 2431 | |
242d9c06 | 2432 | @node Symbols |
93b45514 | 2433 | @chapter Symbols |
66b818fb RP |
2434 | |
2435 | @cindex symbols | |
47342e8f RP |
2436 | Symbols are a central concept: the programmer uses symbols to name |
2437 | things, the linker uses symbols to link, and the debugger uses symbols | |
d0281557 | 2438 | to debug. |
47342e8f | 2439 | |
b50e59fe | 2440 | @quotation |
66b818fb | 2441 | @cindex debuggers, and symbol order |
f009d0ab | 2442 | @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in |
b50e59fe RP |
2443 | the same order they were declared. This may break some debuggers. |
2444 | @end quotation | |
93b45514 | 2445 | |
7a4c8e5c | 2446 | @menu |
ba487f3a RP |
2447 | * Labels:: Labels |
2448 | * Setting Symbols:: Giving Symbols Other Values | |
2449 | * Symbol Names:: Symbol Names | |
2450 | * Dot:: The Special Dot Symbol | |
2451 | * Symbol Attributes:: Symbol Attributes | |
7a4c8e5c RP |
2452 | @end menu |
2453 | ||
242d9c06 | 2454 | @node Labels |
93b45514 | 2455 | @section Labels |
66b818fb RP |
2456 | |
2457 | @cindex labels | |
93b45514 | 2458 | A @dfn{label} is written as a symbol immediately followed by a colon |
b50e59fe | 2459 | @samp{:}. The symbol then represents the current value of the |
93b45514 RP |
2460 | active location counter, and is, for example, a suitable instruction |
2461 | operand. You are warned if you use the same symbol to represent two | |
2462 | different locations: the first definition overrides any other | |
2463 | definitions. | |
2464 | ||
9dcf8057 | 2465 | @ifset HPPA |
81fcb3ff RP |
2466 | On the HPPA, the usual form for a label need not be immediately followed by a |
2467 | colon, but instead must start in column zero. Only one label may be defined on | |
2468 | a single line. To work around this, the HPPA version of @code{@value{AS}} also | |
2469 | provides a special directive @code{.label} for defining labels more flexibly. | |
9dcf8057 JL |
2470 | @end ifset |
2471 | ||
242d9c06 | 2472 | @node Setting Symbols |
93b45514 | 2473 | @section Giving Symbols Other Values |
66b818fb RP |
2474 | |
2475 | @cindex assigning values to symbols | |
2476 | @cindex symbol values, assigning | |
b50e59fe RP |
2477 | A symbol can be given an arbitrary value by writing a symbol, followed |
2478 | by an equals sign @samp{=}, followed by an expression | |
93b45514 | 2479 | (@pxref{Expressions}). This is equivalent to using the @code{.set} |
7a4c8e5c | 2480 | directive. @xref{Set,,@code{.set}}. |
93b45514 | 2481 | |
242d9c06 | 2482 | @node Symbol Names |
93b45514 | 2483 | @section Symbol Names |
66b818fb RP |
2484 | |
2485 | @cindex symbol names | |
2486 | @cindex names, symbol | |
f009d0ab RP |
2487 | @ifclear SPECIAL-SYMS |
2488 | Symbol names begin with a letter or with one of @samp{._}. On most | |
2489 | machines, you can also use @code{$} in symbol names; exceptions are | |
2490 | noted in @ref{Machine Dependencies}. That character may be followed by any | |
2491 | string of digits, letters, dollar signs (unless otherwise noted in | |
2492 | @ref{Machine Dependencies}), and underscores. | |
2493 | @end ifclear | |
2494 | @ifset A29K | |
b50e59fe RP |
2495 | For the AMD 29K family, @samp{?} is also allowed in the |
2496 | body of a symbol name, though not at its beginning. | |
f009d0ab RP |
2497 | @end ifset |
2498 | ||
2499 | @ifset SPECIAL-SYMS | |
2500 | @ifset H8 | |
2501 | Symbol names begin with a letter or with one of @samp{._}. On the | |
f009d0ab | 2502 | Hitachi SH or the |
f009d0ab RP |
2503 | H8/500, you can also use @code{$} in symbol names. That character may |
2504 | be followed by any string of digits, letters, dollar signs (save on the | |
2505 | H8/300), and underscores. | |
2506 | @end ifset | |
2507 | @end ifset | |
2508 | ||
2509 | Case of letters is significant: @code{foo} is a different symbol name | |
2510 | than @code{Foo}. | |
b50e59fe | 2511 | |
05a0e43b RP |
2512 | Each symbol has exactly one name. Each name in an assembly language program |
2513 | refers to exactly one symbol. You may use that symbol name any number of times | |
2514 | in a program. | |
93b45514 | 2515 | |
7a4c8e5c | 2516 | @subheading Local Symbol Names |
93b45514 | 2517 | |
66b818fb RP |
2518 | @cindex local symbol names |
2519 | @cindex symbol names, local | |
2520 | @cindex temporary symbol names | |
2521 | @cindex symbol names, temporary | |
93b45514 | 2522 | Local symbols help compilers and programmers use names temporarily. |
b50e59fe RP |
2523 | There are ten local symbol names, which are re-used throughout the |
2524 | program. You may refer to them using the names @samp{0} @samp{1} | |
2525 | @dots{} @samp{9}. To define a local symbol, write a label of the form | |
2526 | @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most | |
2527 | recent previous definition of that symbol write @samp{@b{N}b}, using the | |
2528 | same digit as when you defined the label. To refer to the next | |
2529 | definition of a local label, write @samp{@b{N}f}---where @b{N} gives you | |
2530 | a choice of 10 forward references. The @samp{b} stands for | |
2531 | ``backwards'' and the @samp{f} stands for ``forwards''. | |
2532 | ||
8babef85 | 2533 | Local symbols are not emitted by the current @sc{gnu} C compiler. |
93b45514 RP |
2534 | |
2535 | There is no restriction on how you can use these labels, but | |
2536 | remember that at any point in the assembly you can refer to at most | |
2537 | 10 prior local labels and to at most 10 forward local labels. | |
2538 | ||
47342e8f | 2539 | Local symbol names are only a notation device. They are immediately |
93b45514 | 2540 | transformed into more conventional symbol names before the assembler |
47342e8f RP |
2541 | uses them. The symbol names stored in the symbol table, appearing in |
2542 | error messages and optionally emitted to the object file have these | |
2543 | parts: | |
2544 | ||
2545 | @table @code | |
93b45514 | 2546 | @item L |
f009d0ab RP |
2547 | All local labels begin with @samp{L}. Normally both @code{@value{AS}} and |
2548 | @code{@value{LD}} forget symbols that start with @samp{L}. These labels are | |
05a0e43b RP |
2549 | used for symbols you are never intended to see. If you use the |
2550 | @samp{-L} option then @code{@value{AS}} retains these symbols in the | |
f009d0ab | 2551 | object file. If you also instruct @code{@value{LD}} to retain these symbols, |
93b45514 | 2552 | you may use them in debugging. |
47342e8f RP |
2553 | |
2554 | @item @var{digit} | |
93b45514 RP |
2555 | If the label is written @samp{0:} then the digit is @samp{0}. |
2556 | If the label is written @samp{1:} then the digit is @samp{1}. | |
2557 | And so on up through @samp{9:}. | |
47342e8f | 2558 | |
35cfacf0 | 2559 | @item @kbd{C-A} |
05a0e43b | 2560 | This unusual character is included so you do not accidentally invent |
93b45514 RP |
2561 | a symbol of the same name. The character has ASCII value |
2562 | @samp{\001}. | |
47342e8f RP |
2563 | |
2564 | @item @emph{ordinal number} | |
2565 | This is a serial number to keep the labels distinct. The first | |
93b45514 | 2566 | @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the |
47342e8f | 2567 | number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:} |
93b45514 RP |
2568 | through @samp{9:}. |
2569 | @end table | |
47342e8f | 2570 | |
35cfacf0 ILT |
2571 | For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th |
2572 | @code{3:} is named @code{L3@kbd{C-A}44}. | |
93b45514 | 2573 | |
242d9c06 | 2574 | @node Dot |
93b45514 RP |
2575 | @section The Special Dot Symbol |
2576 | ||
66b818fb RP |
2577 | @cindex dot (symbol) |
2578 | @cindex @code{.} (symbol) | |
2579 | @cindex current address | |
2580 | @cindex location counter | |
b50e59fe | 2581 | The special symbol @samp{.} refers to the current address that |
f009d0ab | 2582 | @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin: |
05a0e43b | 2583 | .long .} defines @code{melvin} to contain its own address. |
93b45514 RP |
2584 | Assigning a value to @code{.} is treated the same as a @code{.org} |
2585 | directive. Thus, the expression @samp{.=.+4} is the same as saying | |
f009d0ab | 2586 | @ifclear no-space-dir |
09352a5d | 2587 | @samp{.space 4}. |
f009d0ab RP |
2588 | @end ifclear |
2589 | @ifset no-space-dir | |
2590 | @ifset A29K | |
b50e59fe | 2591 | @samp{.block 4}. |
f009d0ab RP |
2592 | @end ifset |
2593 | @end ifset | |
b50e59fe | 2594 | |
242d9c06 | 2595 | @node Symbol Attributes |
93b45514 | 2596 | @section Symbol Attributes |
66b818fb RP |
2597 | |
2598 | @cindex symbol attributes | |
2599 | @cindex attributes, symbol | |
d0281557 | 2600 | Every symbol has, as well as its name, the attributes ``Value'' and |
66b818fb | 2601 | ``Type''. Depending on output format, symbols can also have auxiliary |
f009d0ab RP |
2602 | attributes. |
2603 | @ifset INTERNALS | |
2604 | The detailed definitions are in @file{a.out.h}. | |
2605 | @end ifset | |
93b45514 | 2606 | |
f009d0ab | 2607 | If you use a symbol without defining it, @code{@value{AS}} assumes zero for |
93b45514 RP |
2608 | all these attributes, and probably won't warn you. This makes the |
2609 | symbol an externally defined symbol, which is generally what you | |
2610 | would want. | |
2611 | ||
7a4c8e5c | 2612 | @menu |
ba487f3a RP |
2613 | * Symbol Value:: Value |
2614 | * Symbol Type:: Type | |
f009d0ab RP |
2615 | @ifset aout-bout |
2616 | @ifset GENERIC | |
2617 | * a.out Symbols:: Symbol Attributes: @code{a.out} | |
2618 | @end ifset | |
2619 | @ifclear GENERIC | |
2620 | @ifclear BOUT | |
ba487f3a | 2621 | * a.out Symbols:: Symbol Attributes: @code{a.out} |
f009d0ab RP |
2622 | @end ifclear |
2623 | @ifset BOUT | |
ba487f3a | 2624 | * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out} |
f009d0ab RP |
2625 | @end ifset |
2626 | @end ifclear | |
2627 | @end ifset | |
2628 | @ifset COFF | |
ba487f3a | 2629 | * COFF Symbols:: Symbol Attributes for COFF |
f009d0ab | 2630 | @end ifset |
9dcf8057 JL |
2631 | @ifset SOM |
2632 | * SOM Symbols:: Symbol Attributes for SOM | |
2633 | @end ifset | |
7a4c8e5c RP |
2634 | @end menu |
2635 | ||
242d9c06 | 2636 | @node Symbol Value |
93b45514 | 2637 | @subsection Value |
66b818fb RP |
2638 | |
2639 | @cindex value of a symbol | |
2640 | @cindex symbol value | |
24b1493d RP |
2641 | The value of a symbol is (usually) 32 bits. For a symbol which labels a |
2642 | location in the text, data, bss or absolute sections the value is the | |
2643 | number of addresses from the start of that section to the label. | |
2644 | Naturally for text, data and bss sections the value of a symbol changes | |
f009d0ab | 2645 | as @code{@value{LD}} changes section base addresses during linking. Absolute |
24b1493d RP |
2646 | symbols' values do not change during linking: that is why they are |
2647 | called absolute. | |
93b45514 | 2648 | |
b50e59fe | 2649 | The value of an undefined symbol is treated in a special way. If it is |
05a0e43b RP |
2650 | 0 then the symbol is not defined in this assembler source file, and |
2651 | @code{@value{LD}} tries to determine its value from other files linked into the | |
2652 | same program. You make this kind of symbol simply by mentioning a symbol | |
b50e59fe RP |
2653 | name without defining it. A non-zero value represents a @code{.comm} |
2654 | common declaration. The value is how much common storage to reserve, in | |
2655 | bytes (addresses). The symbol refers to the first address of the | |
2656 | allocated storage. | |
93b45514 | 2657 | |
242d9c06 | 2658 | @node Symbol Type |
93b45514 | 2659 | @subsection Type |
66b818fb RP |
2660 | |
2661 | @cindex type of a symbol | |
2662 | @cindex symbol type | |
24b1493d | 2663 | The type attribute of a symbol contains relocation (section) |
d0281557 RP |
2664 | information, any flag settings indicating that a symbol is external, and |
2665 | (optionally), other information for linkers and debuggers. The exact | |
2666 | format depends on the object-code output format in use. | |
93b45514 | 2667 | |
f009d0ab RP |
2668 | @ifset aout-bout |
2669 | @ifclear GENERIC | |
2670 | @ifset BOUT | |
2671 | @c The following avoids a "widow" subsection title. @group would be | |
2672 | @c better if it were available outside examples. | |
2673 | @need 1000 | |
242d9c06 | 2674 | @node a.out Symbols |
d0281557 | 2675 | @subsection Symbol Attributes: @code{a.out}, @code{b.out} |
66b818fb RP |
2676 | |
2677 | @cindex @code{b.out} symbol attributes | |
2678 | @cindex symbol attributes, @code{b.out} | |
f009d0ab RP |
2679 | These symbol attributes appear only when @code{@value{AS}} is configured for |
2680 | one of the Berkeley-descended object output formats---@code{a.out} or | |
2681 | @code{b.out}. | |
2682 | ||
2683 | @end ifset | |
2684 | @ifclear BOUT | |
2685 | @node a.out Symbols | |
2686 | @subsection Symbol Attributes: @code{a.out} | |
2687 | ||
2688 | @cindex @code{a.out} symbol attributes | |
2689 | @cindex symbol attributes, @code{a.out} | |
2690 | ||
2691 | @end ifclear | |
2692 | @end ifclear | |
2693 | @ifset GENERIC | |
2694 | @node a.out Symbols | |
0b5b143a | 2695 | @subsection Symbol Attributes: @code{a.out} |
7a4c8e5c | 2696 | |
66b818fb RP |
2697 | @cindex @code{a.out} symbol attributes |
2698 | @cindex symbol attributes, @code{a.out} | |
2699 | ||
f009d0ab | 2700 | @end ifset |
7a4c8e5c | 2701 | @menu |
ba487f3a RP |
2702 | * Symbol Desc:: Descriptor |
2703 | * Symbol Other:: Other | |
7a4c8e5c | 2704 | @end menu |
93b45514 | 2705 | |
242d9c06 | 2706 | @node Symbol Desc |
d0281557 | 2707 | @subsubsection Descriptor |
66b818fb RP |
2708 | |
2709 | @cindex descriptor, of @code{a.out} symbol | |
93b45514 | 2710 | This is an arbitrary 16-bit value. You may establish a symbol's |
7a4c8e5c RP |
2711 | descriptor value by using a @code{.desc} statement |
2712 | (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to | |
f009d0ab | 2713 | @code{@value{AS}}. |
93b45514 | 2714 | |
242d9c06 | 2715 | @node Symbol Other |
d0281557 | 2716 | @subsubsection Other |
66b818fb RP |
2717 | |
2718 | @cindex other attribute, of @code{a.out} symbol | |
f009d0ab RP |
2719 | This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}. |
2720 | @end ifset | |
d0281557 | 2721 | |
f009d0ab | 2722 | @ifset COFF |
242d9c06 | 2723 | @node COFF Symbols |
d0281557 | 2724 | @subsection Symbol Attributes for COFF |
66b818fb RP |
2725 | |
2726 | @cindex COFF symbol attributes | |
2727 | @cindex symbol attributes, COFF | |
2728 | ||
d0281557 RP |
2729 | The COFF format supports a multitude of auxiliary symbol attributes; |
2730 | like the primary symbol attributes, they are set between @code{.def} and | |
f009d0ab | 2731 | @code{.endef} directives. |
d0281557 RP |
2732 | |
2733 | @subsubsection Primary Attributes | |
66b818fb RP |
2734 | |
2735 | @cindex primary attributes, COFF symbols | |
d0281557 RP |
2736 | The symbol name is set with @code{.def}; the value and type, |
2737 | respectively, with @code{.val} and @code{.type}. | |
2738 | ||
2739 | @subsubsection Auxiliary Attributes | |
66b818fb RP |
2740 | |
2741 | @cindex auxiliary attributes, COFF symbols | |
f009d0ab | 2742 | The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl}, |
d0281557 RP |
2743 | @code{.size}, and @code{.tag} can generate auxiliary symbol table |
2744 | information for COFF. | |
f009d0ab | 2745 | @end ifset |
93b45514 | 2746 | |
9dcf8057 JL |
2747 | @ifset SOM |
2748 | @node SOM Symbols | |
2749 | @subsection Symbol Attributes for SOM | |
2750 | ||
2751 | @cindex SOM symbol attributes | |
2752 | @cindex symbol attributes, SOM | |
2753 | ||
05a0e43b RP |
2754 | The SOM format for the HPPA supports a multitude of symbol attributes set with |
2755 | the @code{.EXPORT} and @code{.IMPORT} directives. | |
9dcf8057 JL |
2756 | |
2757 | The attributes are described in @cite{HP9000 Series 800 Assembly | |
2758 | Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and | |
2759 | @code{EXPORT} assembler directive documentation. | |
2760 | @end ifset | |
2761 | ||
242d9c06 | 2762 | @node Expressions |
93b45514 | 2763 | @chapter Expressions |
66b818fb RP |
2764 | |
2765 | @cindex expressions | |
2766 | @cindex addresses | |
2767 | @cindex numeric values | |
93b45514 RP |
2768 | An @dfn{expression} specifies an address or numeric value. |
2769 | Whitespace may precede and/or follow an expression. | |
2770 | ||
dd565f85 RP |
2771 | The result of an expression must be an absolute number, or else an offset into |
2772 | a particular section. If an expression is not absolute, and there is not | |
2773 | enough information when @code{@value{AS}} sees the expression to know its | |
2774 | section, a second pass over the source program might be necessary to interpret | |
2775 | the expression---but the second pass is currently not implemented. | |
2776 | @code{@value{AS}} aborts with an error message in this situation. | |
2777 | ||
7a4c8e5c | 2778 | @menu |
ba487f3a RP |
2779 | * Empty Exprs:: Empty Expressions |
2780 | * Integer Exprs:: Integer Expressions | |
7a4c8e5c RP |
2781 | @end menu |
2782 | ||
242d9c06 | 2783 | @node Empty Exprs |
93b45514 | 2784 | @section Empty Expressions |
66b818fb RP |
2785 | |
2786 | @cindex empty expressions | |
2787 | @cindex expressions, empty | |
47342e8f | 2788 | An empty expression has no value: it is just whitespace or null. |
93b45514 | 2789 | Wherever an absolute expression is required, you may omit the |
05a0e43b | 2790 | expression, and @code{@value{AS}} assumes a value of (absolute) 0. This |
93b45514 RP |
2791 | is compatible with other assemblers. |
2792 | ||
242d9c06 | 2793 | @node Integer Exprs |
93b45514 | 2794 | @section Integer Expressions |
66b818fb RP |
2795 | |
2796 | @cindex integer expressions | |
2797 | @cindex expressions, integer | |
47342e8f RP |
2798 | An @dfn{integer expression} is one or more @emph{arguments} delimited |
2799 | by @emph{operators}. | |
2800 | ||
7a4c8e5c | 2801 | @menu |
ba487f3a RP |
2802 | * Arguments:: Arguments |
2803 | * Operators:: Operators | |
2804 | * Prefix Ops:: Prefix Operators | |
2805 | * Infix Ops:: Infix Operators | |
7a4c8e5c RP |
2806 | @end menu |
2807 | ||
242d9c06 | 2808 | @node Arguments |
47342e8f | 2809 | @subsection Arguments |
93b45514 | 2810 | |
66b818fb RP |
2811 | @cindex expression arguments |
2812 | @cindex arguments in expressions | |
2813 | @cindex operands in expressions | |
2814 | @cindex arithmetic operands | |
47342e8f RP |
2815 | @dfn{Arguments} are symbols, numbers or subexpressions. In other |
2816 | contexts arguments are sometimes called ``arithmetic operands''. In | |
2817 | this manual, to avoid confusing them with the ``instruction operands'' of | |
2818 | the machine language, we use the term ``argument'' to refer to parts of | |
b50e59fe | 2819 | expressions only, reserving the word ``operand'' to refer only to machine |
d0281557 | 2820 | instruction operands. |
93b45514 | 2821 | |
24b1493d RP |
2822 | Symbols are evaluated to yield @{@var{section} @var{NNN}@} where |
2823 | @var{section} is one of text, data, bss, absolute, | |
d0281557 | 2824 | or undefined. @var{NNN} is a signed, 2's complement 32 bit |
93b45514 RP |
2825 | integer. |
2826 | ||
2827 | Numbers are usually integers. | |
2828 | ||
2829 | A number can be a flonum or bignum. In this case, you are warned | |
f009d0ab | 2830 | that only the low order 32 bits are used, and @code{@value{AS}} pretends |
93b45514 RP |
2831 | these 32 bits are an integer. You may write integer-manipulating |
2832 | instructions that act on exotic constants, compatible with other | |
2833 | assemblers. | |
2834 | ||
66b818fb | 2835 | @cindex subexpressions |
b50e59fe RP |
2836 | Subexpressions are a left parenthesis @samp{(} followed by an integer |
2837 | expression, followed by a right parenthesis @samp{)}; or a prefix | |
47342e8f | 2838 | operator followed by an argument. |
93b45514 | 2839 | |
242d9c06 | 2840 | @node Operators |
93b45514 | 2841 | @subsection Operators |
66b818fb RP |
2842 | |
2843 | @cindex operators, in expressions | |
2844 | @cindex arithmetic functions | |
2845 | @cindex functions, in expressions | |
b50e59fe RP |
2846 | @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix |
2847 | operators are followed by an argument. Infix operators appear | |
47342e8f | 2848 | between their arguments. Operators may be preceded and/or followed by |
93b45514 RP |
2849 | whitespace. |
2850 | ||
242d9c06 | 2851 | @node Prefix Ops |
66b818fb RP |
2852 | @subsection Prefix Operator |
2853 | ||
2854 | @cindex prefix operators | |
f009d0ab | 2855 | @code{@value{AS}} has the following @dfn{prefix operators}. They each take |
47342e8f | 2856 | one argument, which must be absolute. |
d0281557 RP |
2857 | |
2858 | @c the tex/end tex stuff surrounding this small table is meant to make | |
2859 | @c it align, on the printed page, with the similar table in the next | |
2860 | @c section (which is inside an enumerate). | |
2861 | @tex | |
2862 | \global\advance\leftskip by \itemindent | |
2863 | @end tex | |
2864 | ||
b50e59fe | 2865 | @table @code |
93b45514 | 2866 | @item - |
b50e59fe | 2867 | @dfn{Negation}. Two's complement negation. |
93b45514 | 2868 | @item ~ |
b50e59fe | 2869 | @dfn{Complementation}. Bitwise not. |
93b45514 RP |
2870 | @end table |
2871 | ||
d0281557 RP |
2872 | @tex |
2873 | \global\advance\leftskip by -\itemindent | |
2874 | @end tex | |
2875 | ||
242d9c06 | 2876 | @node Infix Ops |
b50e59fe | 2877 | @subsection Infix Operators |
47342e8f | 2878 | |
66b818fb RP |
2879 | @cindex infix operators |
2880 | @cindex operators, permitted arguments | |
b50e59fe RP |
2881 | @dfn{Infix operators} take two arguments, one on either side. Operators |
2882 | have precedence, but operations with equal precedence are performed left | |
2883 | to right. Apart from @code{+} or @code{-}, both arguments must be | |
2884 | absolute, and the result is absolute. | |
47342e8f | 2885 | |
93b45514 | 2886 | @enumerate |
66b818fb RP |
2887 | @cindex operator precedence |
2888 | @cindex precedence of operators | |
47342e8f | 2889 | |
93b45514 | 2890 | @item |
47342e8f | 2891 | Highest Precedence |
66b818fb | 2892 | |
93b45514 RP |
2893 | @table @code |
2894 | @item * | |
2895 | @dfn{Multiplication}. | |
66b818fb | 2896 | |
93b45514 RP |
2897 | @item / |
2898 | @dfn{Division}. Truncation is the same as the C operator @samp{/} | |
66b818fb | 2899 | |
93b45514 RP |
2900 | @item % |
2901 | @dfn{Remainder}. | |
66b818fb | 2902 | |
f009d0ab RP |
2903 | @item < |
2904 | @itemx << | |
2905 | @dfn{Shift Left}. Same as the C operator @samp{<<}. | |
66b818fb | 2906 | |
f009d0ab RP |
2907 | @item > |
2908 | @itemx >> | |
2909 | @dfn{Shift Right}. Same as the C operator @samp{>>}. | |
93b45514 | 2910 | @end table |
47342e8f | 2911 | |
93b45514 | 2912 | @item |
47342e8f | 2913 | Intermediate precedence |
66b818fb | 2914 | |
47342e8f | 2915 | @table @code |
93b45514 | 2916 | @item | |
66b818fb | 2917 | |
93b45514 | 2918 | @dfn{Bitwise Inclusive Or}. |
66b818fb | 2919 | |
93b45514 RP |
2920 | @item & |
2921 | @dfn{Bitwise And}. | |
66b818fb | 2922 | |
93b45514 RP |
2923 | @item ^ |
2924 | @dfn{Bitwise Exclusive Or}. | |
66b818fb | 2925 | |
93b45514 RP |
2926 | @item ! |
2927 | @dfn{Bitwise Or Not}. | |
2928 | @end table | |
47342e8f | 2929 | |
93b45514 | 2930 | @item |
47342e8f | 2931 | Lowest Precedence |
66b818fb | 2932 | |
47342e8f | 2933 | @table @code |
66b818fb RP |
2934 | @cindex addition, permitted arguments |
2935 | @cindex plus, permitted arguments | |
2936 | @cindex arguments for addition | |
71dd3c40 | 2937 | @item + |
dd565f85 RP |
2938 | @dfn{Addition}. If either argument is absolute, the result has the section of |
2939 | the other argument. You may not add together arguments from different | |
2940 | sections. | |
66b818fb | 2941 | |
66b818fb RP |
2942 | @cindex subtraction, permitted arguments |
2943 | @cindex minus, permitted arguments | |
2944 | @cindex arguments for subtraction | |
71dd3c40 | 2945 | @item - |
47342e8f | 2946 | @dfn{Subtraction}. If the right argument is absolute, the |
24b1493d | 2947 | result has the section of the left argument. |
dd565f85 RP |
2948 | If both arguments are in the same section, the result is absolute. |
2949 | You may not subtract arguments from different sections. | |
2950 | @c FIXME is there still something useful to say about undefined - undefined ? | |
93b45514 RP |
2951 | @end table |
2952 | @end enumerate | |
2953 | ||
dd565f85 RP |
2954 | In short, it's only meaningful to add or subtract the @emph{offsets} in an |
2955 | address; you can only have a defined section in one of the two arguments. | |
47342e8f | 2956 | |
242d9c06 | 2957 | @node Pseudo Ops |
93b45514 | 2958 | @chapter Assembler Directives |
d0281557 | 2959 | |
66b818fb RP |
2960 | @cindex directives, machine independent |
2961 | @cindex pseudo-ops, machine independent | |
2962 | @cindex machine independent directives | |
d0281557 | 2963 | All assembler directives have names that begin with a period (@samp{.}). |
66b818fb | 2964 | The rest of the name is letters, usually in lower case. |
d0281557 | 2965 | |
f009d0ab | 2966 | This chapter discusses directives that are available regardless of the |
8babef85 | 2967 | target machine configuration for the @sc{gnu} assembler. |
f009d0ab RP |
2968 | @ifset GENERIC |
2969 | Some machine configurations provide additional directives. | |
2970 | @xref{Machine Dependencies}. | |
2971 | @end ifset | |
2972 | @ifclear GENERIC | |
2973 | @ifset machine-directives | |
2974 | @xref{Machine Dependencies} for additional directives. | |
2975 | @end ifset | |
2976 | @end ifclear | |
d0281557 | 2977 | |
7a4c8e5c | 2978 | @menu |
ba487f3a | 2979 | * Abort:: @code{.abort} |
f009d0ab RP |
2980 | @ifset COFF |
2981 | * ABORT:: @code{.ABORT} | |
2982 | @end ifset | |
2983 | ||
ba487f3a | 2984 | * Align:: @code{.align @var{abs-expr} , @var{abs-expr}} |
2d8e0f62 | 2985 | * App-File:: @code{.app-file @var{string}} |
ba487f3a RP |
2986 | * Ascii:: @code{.ascii "@var{string}"}@dots{} |
2987 | * Asciz:: @code{.asciz "@var{string}"}@dots{} | |
931a8fab | 2988 | * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}} |
ba487f3a RP |
2989 | * Byte:: @code{.byte @var{expressions}} |
2990 | * Comm:: @code{.comm @var{symbol} , @var{length} } | |
2991 | * Data:: @code{.data @var{subsection}} | |
f009d0ab | 2992 | @ifset COFF |
ba487f3a | 2993 | * Def:: @code{.def @var{name}} |
f009d0ab RP |
2994 | @end ifset |
2995 | @ifset aout-bout | |
ba487f3a | 2996 | * Desc:: @code{.desc @var{symbol}, @var{abs-expression}} |
f009d0ab RP |
2997 | @end ifset |
2998 | @ifset COFF | |
ba487f3a | 2999 | * Dim:: @code{.dim} |
f009d0ab RP |
3000 | @end ifset |
3001 | ||
ba487f3a RP |
3002 | * Double:: @code{.double @var{flonums}} |
3003 | * Eject:: @code{.eject} | |
3004 | * Else:: @code{.else} | |
f009d0ab | 3005 | @ifset COFF |
ba487f3a | 3006 | * Endef:: @code{.endef} |
f009d0ab RP |
3007 | @end ifset |
3008 | ||
ba487f3a RP |
3009 | * Endif:: @code{.endif} |
3010 | * Equ:: @code{.equ @var{symbol}, @var{expression}} | |
35cfacf0 ILT |
3011 | * Equiv:: @code{.equiv @var{symbol}, @var{expression}} |
3012 | * Err:: @code{.err} | |
ba487f3a | 3013 | * Extern:: @code{.extern} |
f009d0ab | 3014 | @ifclear no-file-dir |
ba487f3a | 3015 | * File:: @code{.file @var{string}} |
f009d0ab RP |
3016 | @end ifclear |
3017 | ||
ba487f3a RP |
3018 | * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}} |
3019 | * Float:: @code{.float @var{flonums}} | |
3020 | * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}} | |
3021 | * hword:: @code{.hword @var{expressions}} | |
3022 | * Ident:: @code{.ident} | |
3023 | * If:: @code{.if @var{absolute expression}} | |
3024 | * Include:: @code{.include "@var{file}"} | |
3025 | * Int:: @code{.int @var{expressions}} | |
95074dc3 ILT |
3026 | * Irp:: @code{.irp @var{symbol},@var{values}}@dots{} |
3027 | * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{} | |
ba487f3a | 3028 | * Lcomm:: @code{.lcomm @var{symbol} , @var{length}} |
66b818fb | 3029 | * Lflags:: @code{.lflags} |
f009d0ab | 3030 | @ifclear no-line-dir |
ba487f3a | 3031 | * Line:: @code{.line @var{line-number}} |
f009d0ab RP |
3032 | @end ifclear |
3033 | ||
ba487f3a | 3034 | * Ln:: @code{.ln @var{line-number}} |
910d7df2 | 3035 | * Linkonce:: @code{.linkonce [@var{type}]} |
ba487f3a RP |
3036 | * List:: @code{.list} |
3037 | * Long:: @code{.long @var{expressions}} | |
f009d0ab | 3038 | @ignore |
ba487f3a | 3039 | * Lsym:: @code{.lsym @var{symbol}, @var{expression}} |
f009d0ab RP |
3040 | @end ignore |
3041 | ||
95074dc3 | 3042 | * Macro:: @code{.macro @var{name} @var{args}}@dots{} |
910d7df2 | 3043 | * MRI:: @code{.mri @var{val}} |
95074dc3 | 3044 | |
ba487f3a RP |
3045 | * Nolist:: @code{.nolist} |
3046 | * Octa:: @code{.octa @var{bignums}} | |
3047 | * Org:: @code{.org @var{new-lc} , @var{fill}} | |
931a8fab | 3048 | * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}} |
66b818fb | 3049 | * Psize:: @code{.psize @var{lines}, @var{columns}} |
ba487f3a | 3050 | * Quad:: @code{.quad @var{bignums}} |
95074dc3 | 3051 | * Rept:: @code{.rept @var{count}} |
ba487f3a | 3052 | * Sbttl:: @code{.sbttl "@var{subheading}"} |
f009d0ab | 3053 | @ifset COFF |
ba487f3a | 3054 | * Scl:: @code{.scl @var{class}} |
66b818fb | 3055 | * Section:: @code{.section @var{name}, @var{subsection}} |
f009d0ab RP |
3056 | @end ifset |
3057 | ||
ba487f3a RP |
3058 | * Set:: @code{.set @var{symbol}, @var{expression}} |
3059 | * Short:: @code{.short @var{expressions}} | |
3060 | * Single:: @code{.single @var{flonums}} | |
f009d0ab | 3061 | @ifset COFF |
ba487f3a | 3062 | * Size:: @code{.size} |
f009d0ab RP |
3063 | @end ifset |
3064 | ||
910d7df2 | 3065 | * Skip:: @code{.skip @var{size} , @var{fill}} |
3ffb03b1 | 3066 | * Sleb128:: @code{.sleb128 @var{expressions}} |
ba487f3a | 3067 | * Space:: @code{.space @var{size} , @var{fill}} |
f009d0ab | 3068 | @ifset have-stabs |
ba487f3a | 3069 | * Stab:: @code{.stabd, .stabn, .stabs} |
f009d0ab | 3070 | @end ifset |
e680d737 RP |
3071 | |
3072 | * String:: @code{.string "@var{str}"} | |
35cfacf0 ILT |
3073 | @ifset ELF |
3074 | * Symver:: @code{.symver @var{name},@var{name2@@nodename}} | |
3075 | @end ifset | |
f009d0ab | 3076 | @ifset COFF |
ba487f3a | 3077 | * Tag:: @code{.tag @var{structname}} |
f009d0ab RP |
3078 | @end ifset |
3079 | ||
ba487f3a RP |
3080 | * Text:: @code{.text @var{subsection}} |
3081 | * Title:: @code{.title "@var{heading}"} | |
f009d0ab | 3082 | @ifset COFF |
ba487f3a RP |
3083 | * Type:: @code{.type @var{int}} |
3084 | * Val:: @code{.val @var{addr}} | |
f009d0ab RP |
3085 | @end ifset |
3086 | ||
3ffb03b1 | 3087 | * Uleb128:: @code{.uleb128 @var{expressions}} |
ba487f3a RP |
3088 | * Word:: @code{.word @var{expressions}} |
3089 | * Deprecated:: Deprecated Directives | |
7a4c8e5c RP |
3090 | @end menu |
3091 | ||
242d9c06 | 3092 | @node Abort |
b50e59fe | 3093 | @section @code{.abort} |
66b818fb RP |
3094 | |
3095 | @cindex @code{abort} directive | |
3096 | @cindex stopping the assembly | |
93b45514 RP |
3097 | This directive stops the assembly immediately. It is for |
3098 | compatibility with other assemblers. The original idea was that the | |
d0281557 | 3099 | assembly language source would be piped into the assembler. If the sender |
f009d0ab | 3100 | of the source quit, it could use this directive tells @code{@value{AS}} to |
93b45514 RP |
3101 | quit also. One day @code{.abort} will not be supported. |
3102 | ||
f009d0ab RP |
3103 | @ifset COFF |
3104 | @node ABORT | |
d0281557 | 3105 | @section @code{.ABORT} |
66b818fb RP |
3106 | |
3107 | @cindex @code{ABORT} directive | |
f009d0ab | 3108 | When producing COFF output, @code{@value{AS}} accepts this directive as a |
d0281557 | 3109 | synonym for @samp{.abort}. |
66b818fb | 3110 | |
f009d0ab RP |
3111 | @ifset BOUT |
3112 | When producing @code{b.out} output, @code{@value{AS}} accepts this directive, | |
d0281557 | 3113 | but ignores it. |
f009d0ab RP |
3114 | @end ifset |
3115 | @end ifset | |
d0281557 | 3116 | |
242d9c06 | 3117 | @node Align |
c6c7035c | 3118 | @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
66b818fb RP |
3119 | |
3120 | @cindex padding the location counter | |
66b818fb | 3121 | @cindex @code{align} directive |
c6c7035c MM |
3122 | Pad the location counter (in the current subsection) to a particular storage |
3123 | boundary. The first expression (which must be absolute) is the alignment | |
3124 | required, as described below. | |
3125 | ||
3126 | The second expression (also absolute) gives the fill value to be stored in the | |
3127 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
3128 | padding bytes are normally zero. However, on some systems, if the section is | |
3129 | marked as containing code and the fill value is omitted, the space is filled | |
3130 | with no-op instructions. | |
3131 | ||
3132 | The third expression is also absolute, and is also optional. If it is present, | |
3133 | it is the maximum number of bytes that should be skipped by this alignment | |
3134 | directive. If doing the alignment would require skipping more bytes than the | |
3135 | specified maximum, then the alignment is not done at all. You can omit the | |
3136 | fill value (the second argument) entirely by simply using two commas after the | |
3137 | required alignment; this can be useful if you want the alignment to be filled | |
3138 | with no-op instructions when appropriate. | |
93b45514 | 3139 | |
931a8fab | 3140 | The way the required alignment is specified varies from system to system. |
910d7df2 | 3141 | For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF |
71dd3c40 | 3142 | format, |
931a8fab | 3143 | the first expression is the |
05a0e43b | 3144 | alignment request in bytes. For example @samp{.align 8} advances |
9dcf8057 JL |
3145 | the location counter until it is a multiple of 8. If the location counter |
3146 | is already a multiple of 8, no change is needed. | |
9dcf8057 | 3147 | |
931a8fab KR |
3148 | For other systems, including the i386 using a.out format, it is the |
3149 | number of low-order zero bits the location counter must have after | |
3150 | advancement. For example @samp{.align 3} advances the location | |
3151 | counter until it a multiple of 8. If the location counter is already a | |
3152 | multiple of 8, no change is needed. | |
3153 | ||
3154 | This inconsistency is due to the different behaviors of the various | |
3155 | native assemblers for these systems which GAS must emulate. | |
3156 | GAS also provides @code{.balign} and @code{.p2align} directives, | |
3157 | described later, which have a consistent behavior across all | |
3158 | architectures (but are specific to GAS). | |
93b45514 | 3159 | |
2d8e0f62 RP |
3160 | @node App-File |
3161 | @section @code{.app-file @var{string}} | |
66b818fb RP |
3162 | |
3163 | @cindex logical file name | |
3164 | @cindex file name, logical | |
2d8e0f62 RP |
3165 | @cindex @code{app-file} directive |
3166 | @code{.app-file} | |
f009d0ab | 3167 | @ifclear no-file-dir |
d0281557 | 3168 | (which may also be spelled @samp{.file}) |
f009d0ab RP |
3169 | @end ifclear |
3170 | tells @code{@value{AS}} that we are about to start a new | |
d0281557 RP |
3171 | logical file. @var{string} is the new file name. In general, the |
3172 | filename is recognized whether or not it is surrounded by quotes @samp{"}; | |
b50e59fe RP |
3173 | but if you wish to specify an empty file name is permitted, |
3174 | you must give the quotes--@code{""}. This statement may go away in | |
f009d0ab | 3175 | future: it is only recognized to be compatible with old @code{@value{AS}} |
d0281557 | 3176 | programs.@refill |
b50e59fe | 3177 | |
242d9c06 | 3178 | @node Ascii |
b50e59fe | 3179 | @section @code{.ascii "@var{string}"}@dots{} |
66b818fb RP |
3180 | |
3181 | @cindex @code{ascii} directive | |
3182 | @cindex string literals | |
47342e8f | 3183 | @code{.ascii} expects zero or more string literals (@pxref{Strings}) |
93b45514 RP |
3184 | separated by commas. It assembles each string (with no automatic |
3185 | trailing zero byte) into consecutive addresses. | |
3186 | ||
242d9c06 | 3187 | @node Asciz |
b50e59fe | 3188 | @section @code{.asciz "@var{string}"}@dots{} |
66b818fb RP |
3189 | |
3190 | @cindex @code{asciz} directive | |
3191 | @cindex zero-terminated strings | |
3192 | @cindex null-terminated strings | |
b50e59fe RP |
3193 | @code{.asciz} is just like @code{.ascii}, but each string is followed by |
3194 | a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''. | |
93b45514 | 3195 | |
931a8fab | 3196 | @node Balign |
c6c7035c | 3197 | @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
931a8fab KR |
3198 | |
3199 | @cindex padding the location counter given number of bytes | |
3200 | @cindex @code{balign} directive | |
3201 | Pad the location counter (in the current subsection) to a particular | |
3202 | storage boundary. The first expression (which must be absolute) is the | |
3203 | alignment request in bytes. For example @samp{.balign 8} advances | |
3204 | the location counter until it is a multiple of 8. If the location counter | |
3205 | is already a multiple of 8, no change is needed. | |
3206 | ||
c6c7035c MM |
3207 | The second expression (also absolute) gives the fill value to be stored in the |
3208 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
3209 | padding bytes are normally zero. However, on some systems, if the section is | |
3210 | marked as containing code and the fill value is omitted, the space is filled | |
3211 | with no-op instructions. | |
3212 | ||
3213 | The third expression is also absolute, and is also optional. If it is present, | |
3214 | it is the maximum number of bytes that should be skipped by this alignment | |
3215 | directive. If doing the alignment would require skipping more bytes than the | |
3216 | specified maximum, then the alignment is not done at all. You can omit the | |
3217 | fill value (the second argument) entirely by simply using two commas after the | |
3218 | required alignment; this can be useful if you want the alignment to be filled | |
3219 | with no-op instructions when appropriate. | |
931a8fab | 3220 | |
71dd3c40 ILT |
3221 | @cindex @code{balignw} directive |
3222 | @cindex @code{balignl} directive | |
3223 | The @code{.balignw} and @code{.balignl} directives are variants of the | |
3224 | @code{.balign} directive. The @code{.balignw} directive treats the fill | |
3225 | pattern as a two byte word value. The @code{.balignl} directives treats the | |
3226 | fill pattern as a four byte longword value. For example, @code{.balignw | |
3227 | 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
3228 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
3229 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
3230 | undefined. | |
3231 | ||
242d9c06 | 3232 | @node Byte |
b50e59fe | 3233 | @section @code{.byte @var{expressions}} |
93b45514 | 3234 | |
66b818fb RP |
3235 | @cindex @code{byte} directive |
3236 | @cindex integers, one byte | |
47342e8f | 3237 | @code{.byte} expects zero or more expressions, separated by commas. |
93b45514 RP |
3238 | Each expression is assembled into the next byte. |
3239 | ||
242d9c06 | 3240 | @node Comm |
b50e59fe | 3241 | @section @code{.comm @var{symbol} , @var{length} } |
66b818fb RP |
3242 | |
3243 | @cindex @code{comm} directive | |
3244 | @cindex symbol, common | |
35cfacf0 ILT |
3245 | @code{.comm} declares a common symbol named @var{symbol}. When linking, a |
3246 | common symbol in one object file may be merged with a defined or common symbol | |
3247 | of the same name in another object file. If @code{@value{LD}} does not see a | |
3248 | definition for the symbol--just one or more common symbols--then it will | |
3249 | allocate @var{length} bytes of uninitialized memory. @var{length} must be an | |
3250 | absolute expression. If @code{@value{LD}} sees multiple common symbols with | |
3251 | the same name, and they do not all have the same size, it will allocate space | |
3252 | using the largest size. | |
3253 | ||
3254 | @ifset ELF | |
3255 | When using ELF, the @code{.comm} directive takes an optional third argument. | |
3256 | This is the desired alignment of the symbol, specified as a byte boundary (for | |
3257 | example, an alignment of 16 means that the least significant 4 bits of the | |
3258 | address should be zero). The alignment must be an absolute expression, and it | |
3259 | must be a power of two. If @code{@value{LD}} allocates uninitialized memory | |
3260 | for the common symbol, it will use the alignment when placing the symbol. If | |
3261 | no alignment is specified, @code{@value{AS}} will set the alignment to the | |
3262 | largest power of two less than or equal to the size of the symbol, up to a | |
3263 | maximum of 16. | |
3264 | @end ifset | |
47342e8f | 3265 | |
9dcf8057 JL |
3266 | @ifset HPPA |
3267 | The syntax for @code{.comm} differs slightly on the HPPA. The syntax is | |
509d5555 | 3268 | @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional. |
9dcf8057 JL |
3269 | @end ifset |
3270 | ||
242d9c06 | 3271 | @node Data |
24b1493d | 3272 | @section @code{.data @var{subsection}} |
66b818fb RP |
3273 | |
3274 | @cindex @code{data} directive | |
f009d0ab | 3275 | @code{.data} tells @code{@value{AS}} to assemble the following statements onto the |
24b1493d RP |
3276 | end of the data subsection numbered @var{subsection} (which is an |
3277 | absolute expression). If @var{subsection} is omitted, it defaults | |
93b45514 RP |
3278 | to zero. |
3279 | ||
f009d0ab | 3280 | @ifset COFF |
242d9c06 | 3281 | @node Def |
d0281557 | 3282 | @section @code{.def @var{name}} |
66b818fb RP |
3283 | |
3284 | @cindex @code{def} directive | |
3285 | @cindex COFF symbols, debugging | |
3286 | @cindex debugging COFF symbols | |
d0281557 RP |
3287 | Begin defining debugging information for a symbol @var{name}; the |
3288 | definition extends until the @code{.endef} directive is encountered. | |
f009d0ab | 3289 | @ifset BOUT |
d0281557 | 3290 | |
f009d0ab | 3291 | This directive is only observed when @code{@value{AS}} is configured for COFF |
d0281557 RP |
3292 | format output; when producing @code{b.out}, @samp{.def} is recognized, |
3293 | but ignored. | |
f009d0ab RP |
3294 | @end ifset |
3295 | @end ifset | |
d0281557 | 3296 | |
f009d0ab | 3297 | @ifset aout-bout |
242d9c06 | 3298 | @node Desc |
f4335d56 | 3299 | @section @code{.desc @var{symbol}, @var{abs-expression}} |
66b818fb RP |
3300 | |
3301 | @cindex @code{desc} directive | |
3302 | @cindex COFF symbol descriptor | |
3303 | @cindex symbol descriptor, COFF | |
b50e59fe | 3304 | This directive sets the descriptor of the symbol (@pxref{Symbol Attributes}) |
f4335d56 | 3305 | to the low 16 bits of an absolute expression. |
93b45514 | 3306 | |
f009d0ab RP |
3307 | @ifset COFF |
3308 | The @samp{.desc} directive is not available when @code{@value{AS}} is | |
d0281557 | 3309 | configured for COFF output; it is only for @code{a.out} or @code{b.out} |
05a0e43b RP |
3310 | object format. For the sake of compatibility, @code{@value{AS}} accepts |
3311 | it, but produces no output, when configured for COFF. | |
f009d0ab RP |
3312 | @end ifset |
3313 | @end ifset | |
d0281557 | 3314 | |
f009d0ab | 3315 | @ifset COFF |
242d9c06 | 3316 | @node Dim |
d0281557 | 3317 | @section @code{.dim} |
66b818fb RP |
3318 | |
3319 | @cindex @code{dim} directive | |
3320 | @cindex COFF auxiliary symbol information | |
3321 | @cindex auxiliary symbol information, COFF | |
d0281557 RP |
3322 | This directive is generated by compilers to include auxiliary debugging |
3323 | information in the symbol table. It is only permitted inside | |
3324 | @code{.def}/@code{.endef} pairs. | |
f009d0ab | 3325 | @ifset BOUT |
d0281557 RP |
3326 | |
3327 | @samp{.dim} is only meaningful when generating COFF format output; when | |
f009d0ab | 3328 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 3329 | ignores it. |
f009d0ab RP |
3330 | @end ifset |
3331 | @end ifset | |
d0281557 | 3332 | |
242d9c06 | 3333 | @node Double |
b50e59fe | 3334 | @section @code{.double @var{flonums}} |
66b818fb RP |
3335 | |
3336 | @cindex @code{double} directive | |
3337 | @cindex floating point numbers (double) | |
d0281557 RP |
3338 | @code{.double} expects zero or more flonums, separated by commas. It |
3339 | assembles floating point numbers. | |
f009d0ab | 3340 | @ifset GENERIC |
09352a5d | 3341 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
3342 | @code{@value{AS}} is configured. @xref{Machine Dependencies}. |
3343 | @end ifset | |
3344 | @ifclear GENERIC | |
3345 | @ifset IEEEFLOAT | |
3346 | On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers | |
66b818fb | 3347 | in @sc{ieee} format. |
f009d0ab RP |
3348 | @end ifset |
3349 | @end ifclear | |
b50e59fe | 3350 | |
242d9c06 | 3351 | @node Eject |
66b818fb RP |
3352 | @section @code{.eject} |
3353 | ||
3354 | @cindex @code{eject} directive | |
3355 | @cindex new page, in listings | |
3356 | @cindex page, in listings | |
3357 | @cindex listing control: new page | |
3358 | Force a page break at this point, when generating assembly listings. | |
3359 | ||
242d9c06 | 3360 | @node Else |
b50e59fe | 3361 | @section @code{.else} |
66b818fb RP |
3362 | |
3363 | @cindex @code{else} directive | |
f009d0ab | 3364 | @code{.else} is part of the @code{@value{AS}} support for conditional |
7a4c8e5c RP |
3365 | assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section |
3366 | of code to be assembled if the condition for the preceding @code{.if} | |
3367 | was false. | |
b50e59fe | 3368 | |
f009d0ab | 3369 | @ignore |
7a4c8e5c | 3370 | @node End, Endef, Else, Pseudo Ops |
b50e59fe | 3371 | @section @code{.end} |
66b818fb RP |
3372 | |
3373 | @cindex @code{end} directive | |
b50e59fe RP |
3374 | This doesn't do anything---but isn't an s_ignore, so I suspect it's |
3375 | meant to do something eventually (which is why it isn't documented here | |
3376 | as "for compatibility with blah"). | |
f009d0ab | 3377 | @end ignore |
d0281557 | 3378 | |
f009d0ab | 3379 | @ifset COFF |
242d9c06 | 3380 | @node Endef |
d0281557 | 3381 | @section @code{.endef} |
66b818fb RP |
3382 | |
3383 | @cindex @code{endef} directive | |
d0281557 | 3384 | This directive flags the end of a symbol definition begun with |
f009d0ab RP |
3385 | @code{.def}. |
3386 | @ifset BOUT | |
d0281557 RP |
3387 | |
3388 | @samp{.endef} is only meaningful when generating COFF format output; if | |
f009d0ab | 3389 | @code{@value{AS}} is configured to generate @code{b.out}, it accepts this |
d0281557 | 3390 | directive but ignores it. |
f009d0ab RP |
3391 | @end ifset |
3392 | @end ifset | |
7a4c8e5c | 3393 | |
242d9c06 | 3394 | @node Endif |
b50e59fe | 3395 | @section @code{.endif} |
66b818fb RP |
3396 | |
3397 | @cindex @code{endif} directive | |
f009d0ab | 3398 | @code{.endif} is part of the @code{@value{AS}} support for conditional assembly; |
b50e59fe | 3399 | it marks the end of a block of code that is only assembled |
7a4c8e5c | 3400 | conditionally. @xref{If,,@code{.if}}. |
b50e59fe | 3401 | |
242d9c06 | 3402 | @node Equ |
b50e59fe RP |
3403 | @section @code{.equ @var{symbol}, @var{expression}} |
3404 | ||
66b818fb RP |
3405 | @cindex @code{equ} directive |
3406 | @cindex assigning values to symbols | |
3407 | @cindex symbols, assigning values to | |
d0281557 | 3408 | This directive sets the value of @var{symbol} to @var{expression}. |
7a4c8e5c RP |
3409 | It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}. |
3410 | ||
9dcf8057 JL |
3411 | @ifset HPPA |
3412 | The syntax for @code{equ} on the HPPA is | |
509d5555 | 3413 | @samp{@var{symbol} .equ @var{expression}}. |
9dcf8057 JL |
3414 | @end ifset |
3415 | ||
35cfacf0 ILT |
3416 | @node Equiv |
3417 | @section @code{.equiv @var{symbol}, @var{expression}} | |
3418 | @cindex @code{equiv} directive | |
3419 | The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that | |
3420 | the assembler will signal an error if @var{symbol} is already defined. | |
3421 | ||
3422 | Except for the contents of the error message, this is roughly equivalent to | |
3423 | @smallexample | |
3424 | .ifdef SYM | |
3425 | .err | |
3426 | .endif | |
3427 | .equ SYM,VAL | |
3428 | @end smallexample | |
3429 | ||
3430 | @node Err | |
3431 | @section @code{.err} | |
3432 | @cindex @code{err} directive | |
3433 | If @code{@value{AS}} assembles a @code{.err} directive, it will print an error | |
3434 | message and, unless the @code{-Z} option was used, it will not generate an | |
3435 | object file. This can be used to signal error an conditionally compiled code. | |
3436 | ||
242d9c06 | 3437 | @node Extern |
b50e59fe | 3438 | @section @code{.extern} |
66b818fb RP |
3439 | |
3440 | @cindex @code{extern} directive | |
b50e59fe | 3441 | @code{.extern} is accepted in the source program---for compatibility |
f009d0ab | 3442 | with other assemblers---but it is ignored. @code{@value{AS}} treats |
b50e59fe RP |
3443 | all undefined symbols as external. |
3444 | ||
f009d0ab | 3445 | @ifclear no-file-dir |
242d9c06 | 3446 | @node File |
66b818fb RP |
3447 | @section @code{.file @var{string}} |
3448 | ||
3449 | @cindex @code{file} directive | |
3450 | @cindex logical file name | |
3451 | @cindex file name, logical | |
2d8e0f62 | 3452 | @code{.file} (which may also be spelled @samp{.app-file}) tells |
f009d0ab | 3453 | @code{@value{AS}} that we are about to start a new logical file. |
d0281557 RP |
3454 | @var{string} is the new file name. In general, the filename is |
3455 | recognized whether or not it is surrounded by quotes @samp{"}; but if | |
3456 | you wish to specify an empty file name, you must give the | |
3457 | quotes--@code{""}. This statement may go away in future: it is only | |
f009d0ab RP |
3458 | recognized to be compatible with old @code{@value{AS}} programs. |
3459 | @ifset A29K | |
3460 | In some configurations of @code{@value{AS}}, @code{.file} has already been | |
3461 | removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}. | |
3462 | @end ifset | |
3463 | @end ifclear | |
7a4c8e5c | 3464 | |
242d9c06 | 3465 | @node Fill |
b50e59fe | 3466 | @section @code{.fill @var{repeat} , @var{size} , @var{value}} |
66b818fb RP |
3467 | |
3468 | @cindex @code{fill} directive | |
3469 | @cindex writing patterns in memory | |
3470 | @cindex patterns, writing in memory | |
93b45514 RP |
3471 | @var{result}, @var{size} and @var{value} are absolute expressions. |
3472 | This emits @var{repeat} copies of @var{size} bytes. @var{Repeat} | |
3473 | may be zero or more. @var{Size} may be zero or more, but if it is | |
3474 | more than 8, then it is deemed to have the value 8, compatible with | |
3475 | other people's assemblers. The contents of each @var{repeat} bytes | |
3476 | is taken from an 8-byte number. The highest order 4 bytes are | |
3477 | zero. The lowest order 4 bytes are @var{value} rendered in the | |
f009d0ab | 3478 | byte-order of an integer on the computer @code{@value{AS}} is assembling for. |
93b45514 RP |
3479 | Each @var{size} bytes in a repetition is taken from the lowest order |
3480 | @var{size} bytes of this number. Again, this bizarre behavior is | |
3481 | compatible with other people's assemblers. | |
3482 | ||
d0281557 | 3483 | @var{size} and @var{value} are optional. |
93b45514 RP |
3484 | If the second comma and @var{value} are absent, @var{value} is |
3485 | assumed zero. If the first comma and following tokens are absent, | |
3486 | @var{size} is assumed to be 1. | |
3487 | ||
242d9c06 | 3488 | @node Float |
b50e59fe | 3489 | @section @code{.float @var{flonums}} |
66b818fb RP |
3490 | |
3491 | @cindex floating point numbers (single) | |
3492 | @cindex @code{float} directive | |
b50e59fe | 3493 | This directive assembles zero or more flonums, separated by commas. It |
d0281557 | 3494 | has the same effect as @code{.single}. |
f009d0ab | 3495 | @ifset GENERIC |
09352a5d | 3496 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
3497 | @code{@value{AS}} is configured. |
3498 | @xref{Machine Dependencies}. | |
3499 | @end ifset | |
3500 | @ifclear GENERIC | |
3501 | @ifset IEEEFLOAT | |
3502 | On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers | |
66b818fb | 3503 | in @sc{ieee} format. |
f009d0ab RP |
3504 | @end ifset |
3505 | @end ifclear | |
93b45514 | 3506 | |
242d9c06 | 3507 | @node Global |
b50e59fe | 3508 | @section @code{.global @var{symbol}}, @code{.globl @var{symbol}} |
66b818fb RP |
3509 | |
3510 | @cindex @code{global} directive | |
3511 | @cindex symbol, making visible to linker | |
f009d0ab | 3512 | @code{.global} makes the symbol visible to @code{@value{LD}}. If you define |
93b45514 RP |
3513 | @var{symbol} in your partial program, its value is made available to |
3514 | other partial programs that are linked with it. Otherwise, | |
05a0e43b RP |
3515 | @var{symbol} takes its attributes from a symbol of the same name |
3516 | from another file linked into the same program. | |
93b45514 | 3517 | |
b50e59fe RP |
3518 | Both spellings (@samp{.globl} and @samp{.global}) are accepted, for |
3519 | compatibility with other assemblers. | |
3520 | ||
9dcf8057 | 3521 | @ifset HPPA |
e680d737 RP |
3522 | On the HPPA, @code{.global} is not always enough to make it accessible to other |
3523 | partial programs. You may need the HPPA-only @code{.EXPORT} directive as well. | |
3524 | @xref{HPPA Directives,, HPPA Assembler Directives}. | |
9dcf8057 JL |
3525 | @end ifset |
3526 | ||
242d9c06 | 3527 | @node hword |
d0281557 | 3528 | @section @code{.hword @var{expressions}} |
66b818fb RP |
3529 | |
3530 | @cindex @code{hword} directive | |
3531 | @cindex integers, 16-bit | |
3532 | @cindex numbers, 16-bit | |
3533 | @cindex sixteen bit integers | |
d0281557 RP |
3534 | This expects zero or more @var{expressions}, and emits |
3535 | a 16 bit number for each. | |
3536 | ||
f009d0ab | 3537 | @ifset GENERIC |
d0281557 RP |
3538 | This directive is a synonym for @samp{.short}; depending on the target |
3539 | architecture, it may also be a synonym for @samp{.word}. | |
f009d0ab RP |
3540 | @end ifset |
3541 | @ifclear GENERIC | |
3542 | @ifset W32 | |
d0281557 | 3543 | This directive is a synonym for @samp{.short}. |
f009d0ab RP |
3544 | @end ifset |
3545 | @ifset W16 | |
24b1493d | 3546 | This directive is a synonym for both @samp{.short} and @samp{.word}. |
f009d0ab RP |
3547 | @end ifset |
3548 | @end ifclear | |
d0281557 | 3549 | |
242d9c06 | 3550 | @node Ident |
b50e59fe | 3551 | @section @code{.ident} |
66b818fb RP |
3552 | |
3553 | @cindex @code{ident} directive | |
b50e59fe | 3554 | This directive is used by some assemblers to place tags in object files. |
f009d0ab | 3555 | @code{@value{AS}} simply accepts the directive for source-file |
b50e59fe RP |
3556 | compatibility with such assemblers, but does not actually emit anything |
3557 | for it. | |
3558 | ||
242d9c06 | 3559 | @node If |
b50e59fe | 3560 | @section @code{.if @var{absolute expression}} |
66b818fb RP |
3561 | |
3562 | @cindex conditional assembly | |
3563 | @cindex @code{if} directive | |
b50e59fe RP |
3564 | @code{.if} marks the beginning of a section of code which is only |
3565 | considered part of the source program being assembled if the argument | |
3566 | (which must be an @var{absolute expression}) is non-zero. The end of | |
3567 | the conditional section of code must be marked by @code{.endif} | |
7a4c8e5c | 3568 | (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the |
910d7df2 | 3569 | alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}). |
b50e59fe RP |
3570 | |
3571 | The following variants of @code{.if} are also supported: | |
3572 | @table @code | |
66b818fb | 3573 | @cindex @code{ifdef} directive |
71dd3c40 | 3574 | @item .ifdef @var{symbol} |
b50e59fe RP |
3575 | Assembles the following section of code if the specified @var{symbol} |
3576 | has been defined. | |
3577 | ||
f009d0ab | 3578 | @ignore |
66b818fb | 3579 | @cindex @code{ifeqs} directive |
71dd3c40 | 3580 | @item .ifeqs |
d0281557 | 3581 | Not yet implemented. |
f009d0ab | 3582 | @end ignore |
b50e59fe | 3583 | |
66b818fb RP |
3584 | @cindex @code{ifndef} directive |
3585 | @cindex @code{ifnotdef} directive | |
71dd3c40 | 3586 | @item .ifndef @var{symbol} |
910d7df2 | 3587 | @itemx .ifnotdef @var{symbol} |
b50e59fe RP |
3588 | Assembles the following section of code if the specified @var{symbol} |
3589 | has not been defined. Both spelling variants are equivalent. | |
93b45514 | 3590 | |
f009d0ab | 3591 | @ignore |
b50e59fe | 3592 | @item ifnes |
d0281557 | 3593 | Not yet implemented. |
f009d0ab | 3594 | @end ignore |
b50e59fe RP |
3595 | @end table |
3596 | ||
242d9c06 | 3597 | @node Include |
b50e59fe | 3598 | @section @code{.include "@var{file}"} |
66b818fb RP |
3599 | |
3600 | @cindex @code{include} directive | |
3601 | @cindex supporting files, including | |
3602 | @cindex files, including | |
b50e59fe RP |
3603 | This directive provides a way to include supporting files at specified |
3604 | points in your source program. The code from @var{file} is assembled as | |
3605 | if it followed the point of the @code{.include}; when the end of the | |
3606 | included file is reached, assembly of the original file continues. You | |
3607 | can control the search paths used with the @samp{-I} command-line option | |
7a4c8e5c RP |
3608 | (@pxref{Invoking,,Command-Line Options}). Quotation marks are required |
3609 | around @var{file}. | |
b50e59fe | 3610 | |
242d9c06 | 3611 | @node Int |
b50e59fe | 3612 | @section @code{.int @var{expressions}} |
66b818fb RP |
3613 | |
3614 | @cindex @code{int} directive | |
f009d0ab | 3615 | @cindex integers, 32-bit |
05a0e43b RP |
3616 | Expect zero or more @var{expressions}, of any section, separated by commas. |
3617 | For each expression, emit a number that, at run time, is the value of that | |
3618 | expression. The byte order and bit size of the number depends on what kind | |
3619 | of target the assembly is for. | |
f009d0ab RP |
3620 | |
3621 | @ifclear GENERIC | |
3622 | @ifset H8 | |
8d8ddccb RP |
3623 | On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit |
3624 | integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits | |
3625 | 32-bit integers. | |
f009d0ab RP |
3626 | @end ifset |
3627 | @end ifclear | |
93b45514 | 3628 | |
95074dc3 ILT |
3629 | @node Irp |
3630 | @section @code{.irp @var{symbol},@var{values}}@dots{} | |
3631 | ||
3632 | @cindex @code{irp} directive | |
3633 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
3634 | The sequence of statements starts at the @code{.irp} directive, and is | |
3635 | terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is | |
3636 | set to @var{value}, and the sequence of statements is assembled. If no | |
3637 | @var{value} is listed, the sequence of statements is assembled once, with | |
3638 | @var{symbol} set to the null string. To refer to @var{symbol} within the | |
3639 | sequence of statements, use @var{\symbol}. | |
3640 | ||
3641 | For example, assembling | |
3642 | ||
3643 | @example | |
3644 | .irp param,1,2,3 | |
3645 | move d\param,sp@@- | |
3646 | .endr | |
3647 | @end example | |
3648 | ||
3649 | is equivalent to assembling | |
3650 | ||
3651 | @example | |
3652 | move d1,sp@@- | |
3653 | move d2,sp@@- | |
3654 | move d3,sp@@- | |
3655 | @end example | |
3656 | ||
3657 | @node Irpc | |
3658 | @section @code{.irpc @var{symbol},@var{values}}@dots{} | |
3659 | ||
3660 | @cindex @code{irpc} directive | |
3661 | Evaluate a sequence of statements assigning different values to @var{symbol}. | |
3662 | The sequence of statements starts at the @code{.irpc} directive, and is | |
3663 | terminated by an @code{.endr} directive. For each character in @var{value}, | |
3664 | @var{symbol} is set to the character, and the sequence of statements is | |
3665 | assembled. If no @var{value} is listed, the sequence of statements is | |
3666 | assembled once, with @var{symbol} set to the null string. To refer to | |
3667 | @var{symbol} within the sequence of statements, use @var{\symbol}. | |
3668 | ||
3669 | For example, assembling | |
3670 | ||
3671 | @example | |
3672 | .irpc param,123 | |
3673 | move d\param,sp@@- | |
3674 | .endr | |
3675 | @end example | |
3676 | ||
3677 | is equivalent to assembling | |
3678 | ||
3679 | @example | |
3680 | move d1,sp@@- | |
3681 | move d2,sp@@- | |
3682 | move d3,sp@@- | |
3683 | @end example | |
3684 | ||
242d9c06 | 3685 | @node Lcomm |
b50e59fe | 3686 | @section @code{.lcomm @var{symbol} , @var{length}} |
66b818fb RP |
3687 | |
3688 | @cindex @code{lcomm} directive | |
3689 | @cindex local common symbols | |
3690 | @cindex symbols, local common | |
7a4c8e5c | 3691 | Reserve @var{length} (an absolute expression) bytes for a local common |
24b1493d | 3692 | denoted by @var{symbol}. The section and value of @var{symbol} are |
7a4c8e5c | 3693 | those of the new local common. The addresses are allocated in the bss |
05a0e43b | 3694 | section, so that at run-time the bytes start off zeroed. @var{Symbol} |
7a4c8e5c | 3695 | is not declared global (@pxref{Global,,@code{.global}}), so is normally |
f009d0ab | 3696 | not visible to @code{@value{LD}}. |
93b45514 | 3697 | |
35cfacf0 ILT |
3698 | @ifset GENERIC |
3699 | Some targets permit a third argument to be used with @code{.lcomm}. This | |
3700 | argument specifies the desired alignment of the symbol in the bss section. | |
3701 | @end ifset | |
3702 | ||
9dcf8057 JL |
3703 | @ifset HPPA |
3704 | The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is | |
509d5555 | 3705 | @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional. |
9dcf8057 JL |
3706 | @end ifset |
3707 | ||
242d9c06 | 3708 | @node Lflags |
66b818fb RP |
3709 | @section @code{.lflags} |
3710 | ||
3711 | @cindex @code{lflags} directive (ignored) | |
f009d0ab | 3712 | @code{@value{AS}} accepts this directive, for compatibility with other |
66b818fb RP |
3713 | assemblers, but ignores it. |
3714 | ||
f009d0ab | 3715 | @ifclear no-line-dir |
242d9c06 | 3716 | @node Line |
d0281557 | 3717 | @section @code{.line @var{line-number}} |
66b818fb RP |
3718 | |
3719 | @cindex @code{line} directive | |
f009d0ab RP |
3720 | @end ifclear |
3721 | @ifset no-line-dir | |
242d9c06 | 3722 | @node Ln |
b50e59fe | 3723 | @section @code{.ln @var{line-number}} |
66b818fb RP |
3724 | |
3725 | @cindex @code{ln} directive | |
f009d0ab | 3726 | @end ifset |
66b818fb | 3727 | @cindex logical line number |
f009d0ab | 3728 | @ifset aout-bout |
05a0e43b RP |
3729 | Change the logical line number. @var{line-number} must be an absolute |
3730 | expression. The next line has that logical line number. Therefore any other | |
3731 | statements on the current line (after a statement separator character) are | |
3732 | reported as on logical line number @var{line-number} @minus{} 1. One day | |
3733 | @code{@value{AS}} will no longer support this directive: it is recognized only | |
f009d0ab | 3734 | for compatibility with existing assembler programs. |
7a4c8e5c | 3735 | |
f009d0ab RP |
3736 | @ifset GENERIC |
3737 | @ifset A29K | |
3738 | @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is | |
65fbb2d7 | 3739 | not available; use the synonym @code{.ln} in that context. |
f009d0ab RP |
3740 | @end ifset |
3741 | @end ifset | |
3742 | @end ifset | |
d0281557 | 3743 | |
f009d0ab | 3744 | @ifclear no-line-dir |
d0281557 | 3745 | Even though this is a directive associated with the @code{a.out} or |
05a0e43b RP |
3746 | @code{b.out} object-code formats, @code{@value{AS}} still recognizes it |
3747 | when producing COFF output, and treats @samp{.line} as though it | |
d0281557 | 3748 | were the COFF @samp{.ln} @emph{if} it is found outside a |
f009d0ab | 3749 | @code{.def}/@code{.endef} pair. |
d0281557 RP |
3750 | |
3751 | Inside a @code{.def}, @samp{.line} is, instead, one of the directives | |
3752 | used by compilers to generate auxiliary symbol information for | |
3753 | debugging. | |
f009d0ab | 3754 | @end ifclear |
d0281557 | 3755 | |
910d7df2 C |
3756 | @node Linkonce |
3757 | @section @code{.linkonce [@var{type}]} | |
3758 | @cindex COMDAT | |
3759 | @cindex @code{linkonce} directive | |
3760 | @cindex common sections | |
3761 | Mark the current section so that the linker only includes a single copy of it. | |
3762 | This may be used to include the same section in several different object files, | |
3763 | but ensure that the linker will only include it once in the final output file. | |
3764 | The @code{.linkonce} pseudo-op must be used for each instance of the section. | |
3765 | Duplicate sections are detected based on the section name, so it should be | |
3766 | unique. | |
3767 | ||
3768 | This directive is only supported by a few object file formats; as of this | |
3769 | writing, the only object file format which supports it is the Portable | |
3770 | Executable format used on Windows NT. | |
3771 | ||
3772 | The @var{type} argument is optional. If specified, it must be one of the | |
3773 | following strings. For example: | |
3774 | @smallexample | |
3775 | .linkonce same_size | |
3776 | @end smallexample | |
3777 | Not all types may be supported on all object file formats. | |
3778 | ||
3779 | @table @code | |
3780 | @item discard | |
3781 | Silently discard duplicate sections. This is the default. | |
3782 | ||
3783 | @item one_only | |
3784 | Warn if there are duplicate sections, but still keep only one copy. | |
3785 | ||
3786 | @item same_size | |
3787 | Warn if any of the duplicates have different sizes. | |
3788 | ||
3789 | @item same_contents | |
3790 | Warn if any of the duplicates do not have exactly the same contents. | |
3791 | @end table | |
3792 | ||
242d9c06 | 3793 | @node Ln |
d0281557 | 3794 | @section @code{.ln @var{line-number}} |
66b818fb RP |
3795 | |
3796 | @cindex @code{ln} directive | |
f009d0ab | 3797 | @ifclear no-line-dir |
d0281557 | 3798 | @samp{.ln} is a synonym for @samp{.line}. |
f009d0ab RP |
3799 | @end ifclear |
3800 | @ifset no-line-dir | |
3801 | Tell @code{@value{AS}} to change the logical line number. @var{line-number} | |
05a0e43b | 3802 | must be an absolute expression. The next line has that logical |
7a4c8e5c | 3803 | line number, so any other statements on the current line (after a |
05a0e43b | 3804 | statement separator character @code{;}) are reported as on logical |
d0281557 | 3805 | line number @var{line-number} @minus{} 1. |
f009d0ab | 3806 | @ifset BOUT |
d0281557 | 3807 | |
f009d0ab RP |
3808 | This directive is accepted, but ignored, when @code{@value{AS}} is |
3809 | configured for @code{b.out}; its effect is only associated with COFF | |
3810 | output format. | |
3811 | @end ifset | |
3812 | @end ifset | |
d0281557 | 3813 | |
910d7df2 C |
3814 | @node MRI |
3815 | @section @code{.mri @var{val}} | |
3816 | ||
3817 | @cindex @code{mri} directive | |
3818 | @cindex MRI mode, temporarily | |
3819 | If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If | |
3820 | @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change | |
3821 | affects code assembled until the next @code{.mri} directive, or until the end | |
3822 | of the file. @xref{M, MRI mode, MRI mode}. | |
3823 | ||
242d9c06 | 3824 | @node List |
66b818fb RP |
3825 | @section @code{.list} |
3826 | ||
3827 | @cindex @code{list} directive | |
3828 | @cindex listing control, turning on | |
3829 | Control (in conjunction with the @code{.nolist} directive) whether or | |
3830 | not assembly listings are generated. These two directives maintain an | |
3831 | internal counter (which is zero initially). @code{.list} increments the | |
3832 | counter, and @code{.nolist} decrements it. Assembly listings are | |
3833 | generated whenever the counter is greater than zero. | |
3834 | ||
3835 | By default, listings are disabled. When you enable them (with the | |
3836 | @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}), | |
3837 | the initial value of the listing counter is one. | |
b50e59fe | 3838 | |
242d9c06 | 3839 | @node Long |
b50e59fe | 3840 | @section @code{.long @var{expressions}} |
66b818fb RP |
3841 | |
3842 | @cindex @code{long} directive | |
7a4c8e5c | 3843 | @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}. |
93b45514 | 3844 | |
242d9c06 SC |
3845 | @ignore |
3846 | @c no one seems to know what this is for or whether this description is | |
3847 | @c what it really ought to do | |
3848 | @node Lsym | |
b50e59fe | 3849 | @section @code{.lsym @var{symbol}, @var{expression}} |
66b818fb RP |
3850 | |
3851 | @cindex @code{lsym} directive | |
3852 | @cindex symbol, not referenced in assembly | |
47342e8f | 3853 | @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in |
93b45514 RP |
3854 | the hash table, ensuring it cannot be referenced by name during the |
3855 | rest of the assembly. This sets the attributes of the symbol to be | |
47342e8f | 3856 | the same as the expression value: |
d0281557 | 3857 | @smallexample |
b50e59fe | 3858 | @var{other} = @var{descriptor} = 0 |
24b1493d | 3859 | @var{type} = @r{(section of @var{expression})} |
b50e59fe | 3860 | @var{value} = @var{expression} |
d0281557 RP |
3861 | @end smallexample |
3862 | @noindent | |
3863 | The new symbol is not flagged as external. | |
242d9c06 | 3864 | @end ignore |
93b45514 | 3865 | |
95074dc3 ILT |
3866 | @node Macro |
3867 | @section @code{.macro} | |
3868 | ||
3869 | @cindex macros | |
3870 | The commands @code{.macro} and @code{.endm} allow you to define macros that | |
3871 | generate assembly output. For example, this definition specifies a macro | |
3872 | @code{sum} that puts a sequence of numbers into memory: | |
3873 | ||
3874 | @example | |
3875 | .macro sum from=0, to=5 | |
3876 | .long \from | |
3877 | .if \to-\from | |
3878 | sum "(\from+1)",\to | |
3879 | .endif | |
3880 | .endm | |
3881 | @end example | |
3882 | ||
3883 | @noindent | |
3884 | With that definition, @samp{SUM 0,5} is equivalent to this assembly input: | |
3885 | ||
3886 | @example | |
3887 | .long 0 | |
3888 | .long 1 | |
3889 | .long 2 | |
3890 | .long 3 | |
3891 | .long 4 | |
3892 | .long 5 | |
3893 | @end example | |
3894 | ||
3895 | @ftable @code | |
3896 | @item .macro @var{macname} | |
3897 | @itemx .macro @var{macname} @var{macargs} @dots{} | |
3898 | @cindex @code{macro} directive | |
3899 | Begin the definition of a macro called @var{macname}. If your macro | |
3900 | definition requires arguments, specify their names after the macro name, | |
3901 | separated by commas or spaces. You can supply a default value for any | |
3902 | macro argument by following the name with @samp{=@var{deflt}}. For | |
3903 | example, these are all valid @code{.macro} statements: | |
3904 | ||
3905 | @table @code | |
3906 | @item .macro comm | |
3907 | Begin the definition of a macro called @code{comm}, which takes no | |
3908 | arguments. | |
3909 | ||
3910 | @item .macro plus1 p, p1 | |
3911 | @itemx .macro plus1 p p1 | |
3912 | Either statement begins the definition of a macro called @code{plus1}, | |
3913 | which takes two arguments; within the macro definition, write | |
3914 | @samp{\p} or @samp{\p1} to evaluate the arguments. | |
3915 | ||
3916 | @item .macro reserve_str p1=0 p2 | |
3917 | Begin the definition of a macro called @code{reserve_str}, with two | |
3918 | arguments. The first argument has a default value, but not the second. | |
3919 | After the definition is complete, you can call the macro either as | |
3920 | @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to | |
3921 | @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str | |
3922 | ,@var{b}} (with @samp{\p1} evaluating as the default, in this case | |
3923 | @samp{0}, and @samp{\p2} evaluating to @var{b}). | |
3924 | @end table | |
3925 | ||
3926 | When you call a macro, you can specify the argument values either by | |
3927 | position, or by keyword. For example, @samp{sum 9,17} is equivalent to | |
3928 | @samp{sum to=17, from=9}. | |
3929 | ||
3930 | @item .endm | |
3931 | @cindex @code{endm} directive | |
3932 | Mark the end of a macro definition. | |
3933 | ||
3934 | @item .exitm | |
3935 | @cindex @code{exitm} directive | |
3936 | Exit early from the current macro definition. | |
3937 | ||
3938 | @cindex number of macros executed | |
3939 | @cindex macros, count executed | |
3940 | @item \@@ | |
3941 | @code{@value{AS}} maintains a counter of how many macros it has | |
3942 | executed in this pseudo-variable; you can copy that number to your | |
3943 | output with @samp{\@@}, but @emph{only within a macro definition}. | |
3944 | ||
3945 | @ignore | |
3946 | @item LOCAL @var{name} [ , @dots{} ] | |
3947 | @emph{Warning: @code{LOCAL} is only available if you select ``alternate | |
3948 | macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,, | |
3949 | Alternate macro syntax}. | |
3950 | ||
3951 | Generate a string replacement for each of the @var{name} arguments, and | |
3952 | replace any instances of @var{name} in each macro expansion. The | |
3953 | replacement string is unique in the assembly, and different for each | |
3954 | separate macro expansion. @code{LOCAL} allows you to write macros that | |
3955 | define symbols, without fear of conflict between separate macro expansions. | |
3956 | @end ignore | |
3957 | @end ftable | |
3958 | ||
242d9c06 | 3959 | @node Nolist |
66b818fb RP |
3960 | @section @code{.nolist} |
3961 | ||
3962 | @cindex @code{nolist} directive | |
3963 | @cindex listing control, turning off | |
3964 | Control (in conjunction with the @code{.list} directive) whether or | |
3965 | not assembly listings are generated. These two directives maintain an | |
3966 | internal counter (which is zero initially). @code{.list} increments the | |
3967 | counter, and @code{.nolist} decrements it. Assembly listings are | |
3968 | generated whenever the counter is greater than zero. | |
3969 | ||
242d9c06 | 3970 | @node Octa |
b50e59fe | 3971 | @section @code{.octa @var{bignums}} |
66b818fb RP |
3972 | |
3973 | @c FIXME: double size emitted for "octa" on i960, others? Or warn? | |
3974 | @cindex @code{octa} directive | |
3975 | @cindex integer, 16-byte | |
3976 | @cindex sixteen byte integer | |
47342e8f | 3977 | This directive expects zero or more bignums, separated by commas. For each |
b50e59fe RP |
3978 | bignum, it emits a 16-byte integer. |
3979 | ||
d0281557 RP |
3980 | The term ``octa'' comes from contexts in which a ``word'' is two bytes; |
3981 | hence @emph{octa}-word for 16 bytes. | |
93b45514 | 3982 | |
242d9c06 | 3983 | @node Org |
b50e59fe | 3984 | @section @code{.org @var{new-lc} , @var{fill}} |
47342e8f | 3985 | |
66b818fb RP |
3986 | @cindex @code{org} directive |
3987 | @cindex location counter, advancing | |
3988 | @cindex advancing location counter | |
3989 | @cindex current address, advancing | |
05a0e43b | 3990 | Advance the location counter of the current section to |
93b45514 | 3991 | @var{new-lc}. @var{new-lc} is either an absolute expression or an |
24b1493d RP |
3992 | expression with the same section as the current subsection. That is, |
3993 | you can't use @code{.org} to cross sections: if @var{new-lc} has the | |
3994 | wrong section, the @code{.org} directive is ignored. To be compatible | |
3995 | with former assemblers, if the section of @var{new-lc} is absolute, | |
05a0e43b | 3996 | @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc} |
24b1493d | 3997 | is the same as the current subsection. |
47342e8f RP |
3998 | |
3999 | @code{.org} may only increase the location counter, or leave it | |
4000 | unchanged; you cannot use @code{.org} to move the location counter | |
d0281557 | 4001 | backwards. |
47342e8f | 4002 | |
b50e59fe RP |
4003 | @c double negative used below "not undefined" because this is a specific |
4004 | @c reference to "undefined" (as SEG_UNKNOWN is called in this manual) | |
71dd3c40 | 4005 | @c section. doc@cygnus.com 18feb91 |
dd565f85 | 4006 | Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc} |
b50e59fe | 4007 | may not be undefined. If you really detest this restriction we eagerly await |
d0281557 | 4008 | a chance to share your improved assembler. |
93b45514 | 4009 | |
24b1493d RP |
4010 | Beware that the origin is relative to the start of the section, not |
4011 | to the start of the subsection. This is compatible with other | |
93b45514 RP |
4012 | people's assemblers. |
4013 | ||
24b1493d | 4014 | When the location counter (of the current subsection) is advanced, the |
93b45514 RP |
4015 | intervening bytes are filled with @var{fill} which should be an |
4016 | absolute expression. If the comma and @var{fill} are omitted, | |
4017 | @var{fill} defaults to zero. | |
4018 | ||
931a8fab | 4019 | @node P2align |
c6c7035c | 4020 | @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}} |
931a8fab KR |
4021 | |
4022 | @cindex padding the location counter given a power of two | |
4023 | @cindex @code{p2align} directive | |
4024 | Pad the location counter (in the current subsection) to a particular | |
4025 | storage boundary. The first expression (which must be absolute) is the | |
4026 | number of low-order zero bits the location counter must have after | |
4027 | advancement. For example @samp{.p2align 3} advances the location | |
4028 | counter until it a multiple of 8. If the location counter is already a | |
4029 | multiple of 8, no change is needed. | |
4030 | ||
c6c7035c MM |
4031 | The second expression (also absolute) gives the fill value to be stored in the |
4032 | padding bytes. It (and the comma) may be omitted. If it is omitted, the | |
4033 | padding bytes are normally zero. However, on some systems, if the section is | |
4034 | marked as containing code and the fill value is omitted, the space is filled | |
4035 | with no-op instructions. | |
4036 | ||
4037 | The third expression is also absolute, and is also optional. If it is present, | |
4038 | it is the maximum number of bytes that should be skipped by this alignment | |
4039 | directive. If doing the alignment would require skipping more bytes than the | |
4040 | specified maximum, then the alignment is not done at all. You can omit the | |
4041 | fill value (the second argument) entirely by simply using two commas after the | |
4042 | required alignment; this can be useful if you want the alignment to be filled | |
4043 | with no-op instructions when appropriate. | |
931a8fab | 4044 | |
71dd3c40 ILT |
4045 | @cindex @code{p2alignw} directive |
4046 | @cindex @code{p2alignl} directive | |
4047 | The @code{.p2alignw} and @code{.p2alignl} directives are variants of the | |
4048 | @code{.p2align} directive. The @code{.p2alignw} directive treats the fill | |
4049 | pattern as a two byte word value. The @code{.p2alignl} directives treats the | |
4050 | fill pattern as a four byte longword value. For example, @code{.p2alignw | |
4051 | 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be | |
4052 | filled in with the value 0x368d (the exact placement of the bytes depends upon | |
4053 | the endianness of the processor). If it skips 1 or 3 bytes, the fill value is | |
4054 | undefined. | |
4055 | ||
242d9c06 | 4056 | @node Psize |
66b818fb RP |
4057 | @section @code{.psize @var{lines} , @var{columns}} |
4058 | ||
4059 | @cindex @code{psize} directive | |
4060 | @cindex listing control: paper size | |
4061 | @cindex paper size, for listings | |
4062 | Use this directive to declare the number of lines---and, optionally, the | |
f009d0ab | 4063 | number of columns---to use for each page, when generating listings. |
66b818fb | 4064 | |
05a0e43b | 4065 | If you do not use @code{.psize}, listings use a default line-count |
66b818fb RP |
4066 | of 60. You may omit the comma and @var{columns} specification; the |
4067 | default width is 200 columns. | |
4068 | ||
05a0e43b | 4069 | @code{@value{AS}} generates formfeeds whenever the specified number of |
66b818fb | 4070 | lines is exceeded (or whenever you explicitly request one, using |
f009d0ab | 4071 | @code{.eject}). |
66b818fb RP |
4072 | |
4073 | If you specify @var{lines} as @code{0}, no formfeeds are generated save | |
4074 | those explicitly specified with @code{.eject}. | |
4075 | ||
242d9c06 | 4076 | @node Quad |
b50e59fe | 4077 | @section @code{.quad @var{bignums}} |
66b818fb RP |
4078 | |
4079 | @cindex @code{quad} directive | |
b50e59fe | 4080 | @code{.quad} expects zero or more bignums, separated by commas. For |
d0281557 | 4081 | each bignum, it emits |
f009d0ab RP |
4082 | @ifclear bignum-16 |
4083 | an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a | |
4084 | warning message; and just takes the lowest order 8 bytes of the bignum. | |
66b818fb RP |
4085 | @cindex eight-byte integer |
4086 | @cindex integer, 8-byte | |
b50e59fe | 4087 | |
d0281557 | 4088 | The term ``quad'' comes from contexts in which a ``word'' is two bytes; |
b50e59fe | 4089 | hence @emph{quad}-word for 8 bytes. |
f009d0ab RP |
4090 | @end ifclear |
4091 | @ifset bignum-16 | |
d0281557 | 4092 | a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a |
f009d0ab | 4093 | warning message; and just takes the lowest order 16 bytes of the bignum. |
66b818fb RP |
4094 | @cindex sixteen-byte integer |
4095 | @cindex integer, 16-byte | |
f009d0ab | 4096 | @end ifset |
d0281557 | 4097 | |
95074dc3 ILT |
4098 | @node Rept |
4099 | @section @code{.rept @var{count}} | |
4100 | ||
4101 | @cindex @code{rept} directive | |
4102 | Repeat the sequence of lines between the @code{.rept} directive and the next | |
4103 | @code{.endr} directive @var{count} times. | |
4104 | ||
4105 | For example, assembling | |
4106 | ||
4107 | @example | |
4108 | .rept 3 | |
4109 | .long 0 | |
4110 | .endr | |
4111 | @end example | |
4112 | ||
4113 | is equivalent to assembling | |
4114 | ||
4115 | @example | |
4116 | .long 0 | |
4117 | .long 0 | |
4118 | .long 0 | |
4119 | @end example | |
4120 | ||
242d9c06 | 4121 | @node Sbttl |
66b818fb RP |
4122 | @section @code{.sbttl "@var{subheading}"} |
4123 | ||
4124 | @cindex @code{sbttl} directive | |
4125 | @cindex subtitles for listings | |
4126 | @cindex listing control: subtitle | |
4127 | Use @var{subheading} as the title (third line, immediately after the | |
f009d0ab | 4128 | title line) when generating assembly listings. |
66b818fb RP |
4129 | |
4130 | This directive affects subsequent pages, as well as the current page if | |
4131 | it appears within ten lines of the top of a page. | |
4132 | ||
f009d0ab | 4133 | @ifset COFF |
242d9c06 | 4134 | @node Scl |
d0281557 | 4135 | @section @code{.scl @var{class}} |
66b818fb RP |
4136 | |
4137 | @cindex @code{scl} directive | |
4138 | @cindex symbol storage class (COFF) | |
4139 | @cindex COFF symbol storage class | |
d0281557 RP |
4140 | Set the storage-class value for a symbol. This directive may only be |
4141 | used inside a @code{.def}/@code{.endef} pair. Storage class may flag | |
4142 | whether a symbol is static or external, or it may record further | |
4143 | symbolic debugging information. | |
f009d0ab | 4144 | @ifset BOUT |
d0281557 RP |
4145 | |
4146 | The @samp{.scl} directive is primarily associated with COFF output; when | |
05a0e43b RP |
4147 | configured to generate @code{b.out} output format, @code{@value{AS}} |
4148 | accepts this directive but ignores it. | |
f009d0ab RP |
4149 | @end ifset |
4150 | @end ifset | |
d0281557 | 4151 | |
242d9c06 | 4152 | @node Section |
868c3513 | 4153 | @section @code{.section @var{name}} |
66b818fb RP |
4154 | |
4155 | @cindex @code{section} directive | |
868c3513 ILT |
4156 | @cindex named section |
4157 | Use the @code{.section} directive to assemble the following code into a section | |
4158 | named @var{name}. | |
4159 | ||
4b9f4409 KR |
4160 | This directive is only supported for targets that actually support arbitrarily |
4161 | named sections; on @code{a.out} targets, for example, it is not accepted, even | |
868c3513 ILT |
4162 | with a standard @code{a.out} section name. |
4163 | ||
4164 | @ifset COFF | |
4165 | For COFF targets, the @code{.section} directive is used in one of the following | |
4166 | ways: | |
4167 | @smallexample | |
4168 | .section @var{name}[, "@var{flags}"] | |
4169 | .section @var{name}[, @var{subsegment}] | |
4170 | @end smallexample | |
4171 | ||
4172 | If the optional argument is quoted, it is taken as flags to use for the | |
4173 | section. Each flag is a single character. The following flags are recognized: | |
4174 | @table @code | |
4175 | @item b | |
4176 | bss section (uninitialized data) | |
4177 | @item n | |
4178 | section is not loaded | |
4179 | @item w | |
4180 | writable section | |
4181 | @item d | |
4182 | data section | |
35cfacf0 ILT |
4183 | @item r |
4184 | read-only section | |
868c3513 ILT |
4185 | @item x |
4186 | executable section | |
4187 | @end table | |
4188 | ||
4189 | If no flags are specified, the default flags depend upon the section name. If | |
4190 | the section name is not recognized, the default will be for the section to be | |
4191 | loaded and writable. | |
4192 | ||
4193 | If the optional argument to the @code{.section} directive is not quoted, it is | |
4194 | taken as a subsegment number (@pxref{Sub-Sections}). | |
4b9f4409 | 4195 | @end ifset |
868c3513 ILT |
4196 | |
4197 | @ifset ELF | |
4198 | For ELF targets, the @code{.section} directive is used like this: | |
4199 | @smallexample | |
4200 | .section @var{name}[, "@var{flags}"[, @@@var{type}]] | |
4201 | @end smallexample | |
4202 | The optional @var{flags} argument is a quoted string which may contain any | |
4203 | combintion of the following characters: | |
4204 | @table @code | |
4205 | @item a | |
4206 | section is allocatable | |
4207 | @item w | |
4208 | section is writable | |
4209 | @item x | |
4210 | section is executable | |
4211 | @end table | |
4212 | ||
4213 | The optional @var{type} argument may contain one of the following constants: | |
4214 | @table @code | |
4215 | @item @@progbits | |
4216 | section contains data | |
4217 | @item @@nobits | |
4218 | section does not contain data (i.e., section only occupies space) | |
4219 | @end table | |
4220 | ||
4221 | If no flags are specified, the default flags depend upon the section name. If | |
4222 | the section name is not recognized, the default will be for the section to have | |
4223 | none of the above flags: it will not be allocated in memory, nor writable, nor | |
4224 | executable. The section will contain data. | |
4225 | ||
4226 | For ELF targets, the assembler supports another type of @code{.section} | |
4227 | directive for compatibility with the Solaris assembler: | |
4228 | @smallexample | |
4229 | .section "@var{name}"[, @var{flags}...] | |
4230 | @end smallexample | |
4231 | Note that the section name is quoted. There may be a sequence of comma | |
4232 | separated flags: | |
4233 | @table @code | |
4234 | @item #alloc | |
4235 | section is allocatable | |
4236 | @item #write | |
4237 | section is writable | |
4238 | @item #execinstr | |
4239 | section is executable | |
4240 | @end table | |
f009d0ab | 4241 | @end ifset |
242d9c06 SC |
4242 | |
4243 | @node Set | |
b50e59fe | 4244 | @section @code{.set @var{symbol}, @var{expression}} |
93b45514 | 4245 | |
66b818fb RP |
4246 | @cindex @code{set} directive |
4247 | @cindex symbol value, setting | |
05a0e43b RP |
4248 | Set the value of @var{symbol} to @var{expression}. This |
4249 | changes @var{symbol}'s value and type to conform to | |
d0281557 | 4250 | @var{expression}. If @var{symbol} was flagged as external, it remains |
c6c7035c | 4251 | flagged (@pxref{Symbol Attributes}). |
93b45514 | 4252 | |
47342e8f | 4253 | You may @code{.set} a symbol many times in the same assembly. |
93b45514 RP |
4254 | |
4255 | If you @code{.set} a global symbol, the value stored in the object | |
4256 | file is the last value stored into it. | |
4257 | ||
9dcf8057 JL |
4258 | @ifset HPPA |
4259 | The syntax for @code{set} on the HPPA is | |
509d5555 | 4260 | @samp{@var{symbol} .set @var{expression}}. |
9dcf8057 JL |
4261 | @end ifset |
4262 | ||
242d9c06 | 4263 | @node Short |
b50e59fe | 4264 | @section @code{.short @var{expressions}} |
66b818fb RP |
4265 | |
4266 | @cindex @code{short} directive | |
f009d0ab RP |
4267 | @ifset GENERIC |
4268 | @code{.short} is normally the same as @samp{.word}. | |
4269 | @xref{Word,,@code{.word}}. | |
4270 | ||
7a4c8e5c | 4271 | In some configurations, however, @code{.short} and @code{.word} generate |
f009d0ab RP |
4272 | numbers of different lengths; @pxref{Machine Dependencies}. |
4273 | @end ifset | |
4274 | @ifclear GENERIC | |
4275 | @ifset W16 | |
4276 | @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}. | |
4277 | @end ifset | |
4278 | @ifset W32 | |
b50e59fe RP |
4279 | This expects zero or more @var{expressions}, and emits |
4280 | a 16 bit number for each. | |
f009d0ab RP |
4281 | @end ifset |
4282 | @end ifclear | |
242d9c06 SC |
4283 | |
4284 | @node Single | |
b50e59fe | 4285 | @section @code{.single @var{flonums}} |
66b818fb RP |
4286 | |
4287 | @cindex @code{single} directive | |
4288 | @cindex floating point numbers (single) | |
b50e59fe | 4289 | This directive assembles zero or more flonums, separated by commas. It |
d0281557 | 4290 | has the same effect as @code{.float}. |
f009d0ab | 4291 | @ifset GENERIC |
09352a5d | 4292 | The exact kind of floating point numbers emitted depends on how |
f009d0ab RP |
4293 | @code{@value{AS}} is configured. @xref{Machine Dependencies}. |
4294 | @end ifset | |
4295 | @ifclear GENERIC | |
4296 | @ifset IEEEFLOAT | |
4297 | On the @value{TARGET} family, @code{.single} emits 32-bit floating point | |
66b818fb | 4298 | numbers in @sc{ieee} format. |
f009d0ab RP |
4299 | @end ifset |
4300 | @end ifclear | |
d0281557 | 4301 | |
f009d0ab | 4302 | @ifset COFF |
242d9c06 | 4303 | @node Size |
d0281557 | 4304 | @section @code{.size} |
66b818fb RP |
4305 | |
4306 | @cindex @code{size} directive | |
d0281557 RP |
4307 | This directive is generated by compilers to include auxiliary debugging |
4308 | information in the symbol table. It is only permitted inside | |
4309 | @code{.def}/@code{.endef} pairs. | |
f009d0ab | 4310 | @ifset BOUT |
d0281557 RP |
4311 | |
4312 | @samp{.size} is only meaningful when generating COFF format output; when | |
f009d0ab | 4313 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 4314 | ignores it. |
f009d0ab RP |
4315 | @end ifset |
4316 | @end ifset | |
7a4c8e5c | 4317 | |
3ffb03b1 DE |
4318 | @node Sleb128 |
4319 | @section @code{.sleb128 @var{expressions}} | |
4320 | ||
4321 | @cindex @code{sleb128} directive | |
4322 | @var{sleb128} stands for ``signed little endian base 128.'' This is a | |
4323 | compact, variable length representation of numbers used by the DWARF | |
4324 | symbolic debugging format. @xref{Uleb128,@code{.uleb128}}. | |
4325 | ||
f009d0ab | 4326 | @ifclear no-space-dir |
910d7df2 C |
4327 | @node Skip |
4328 | @section @code{.skip @var{size} , @var{fill}} | |
4329 | ||
4330 | @cindex @code{skip} directive | |
4331 | @cindex filling memory | |
4332 | This directive emits @var{size} bytes, each of value @var{fill}. Both | |
4333 | @var{size} and @var{fill} are absolute expressions. If the comma and | |
4334 | @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as | |
4335 | @samp{.space}. | |
4336 | ||
242d9c06 | 4337 | @node Space |
b50e59fe | 4338 | @section @code{.space @var{size} , @var{fill}} |
66b818fb RP |
4339 | |
4340 | @cindex @code{space} directive | |
4341 | @cindex filling memory | |
47342e8f | 4342 | This directive emits @var{size} bytes, each of value @var{fill}. Both |
93b45514 | 4343 | @var{size} and @var{fill} are absolute expressions. If the comma |
910d7df2 C |
4344 | and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same |
4345 | as @samp{.skip}. | |
05a0e43b RP |
4346 | |
4347 | @ifset HPPA | |
4348 | @quotation | |
4349 | @emph{Warning:} @code{.space} has a completely different meaning for HPPA | |
e680d737 RP |
4350 | targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800 |
4351 | Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the | |
4352 | @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives}, | |
4353 | for a summary. | |
05a0e43b RP |
4354 | @end quotation |
4355 | @end ifset | |
f009d0ab | 4356 | @end ifclear |
b50e59fe | 4357 | |
f009d0ab RP |
4358 | @ifset A29K |
4359 | @ifclear GENERIC | |
4360 | @node Space | |
24b1493d | 4361 | @section @code{.space} |
66b818fb | 4362 | @cindex @code{space} directive |
f009d0ab | 4363 | @end ifclear |
7a4c8e5c RP |
4364 | On the AMD 29K, this directive is ignored; it is accepted for |
4365 | compatibility with other AMD 29K assemblers. | |
b50e59fe RP |
4366 | |
4367 | @quotation | |
8babef85 | 4368 | @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive |
f009d0ab | 4369 | @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}. |
b50e59fe | 4370 | @end quotation |
f009d0ab | 4371 | @end ifset |
93b45514 | 4372 | |
f009d0ab | 4373 | @ifset have-stabs |
242d9c06 | 4374 | @node Stab |
b50e59fe | 4375 | @section @code{.stabd, .stabn, .stabs} |
66b818fb RP |
4376 | |
4377 | @cindex symbolic debuggers, information for | |
4378 | @cindex @code{stab@var{x}} directives | |
47342e8f | 4379 | There are three directives that begin @samp{.stab}. |
b50e59fe | 4380 | All emit symbols (@pxref{Symbols}), for use by symbolic debuggers. |
f009d0ab | 4381 | The symbols are not entered in the @code{@value{AS}} hash table: they |
d0281557 | 4382 | cannot be referenced elsewhere in the source file. |
93b45514 | 4383 | Up to five fields are required: |
f009d0ab | 4384 | |
93b45514 RP |
4385 | @table @var |
4386 | @item string | |
f009d0ab RP |
4387 | This is the symbol's name. It may contain any character except |
4388 | @samp{\000}, so is more general than ordinary symbol names. Some | |
4389 | debuggers used to code arbitrarily complex structures into symbol names | |
4390 | using this field. | |
4391 | ||
93b45514 | 4392 | @item type |
f009d0ab RP |
4393 | An absolute expression. The symbol's type is set to the low 8 bits of |
4394 | this expression. Any bit pattern is permitted, but @code{@value{LD}} | |
05a0e43b | 4395 | and debuggers choke on silly bit patterns. |
f009d0ab | 4396 | |
93b45514 | 4397 | @item other |
f009d0ab RP |
4398 | An absolute expression. The symbol's ``other'' attribute is set to the |
4399 | low 8 bits of this expression. | |
4400 | ||
93b45514 | 4401 | @item desc |
f009d0ab RP |
4402 | An absolute expression. The symbol's descriptor is set to the low 16 |
4403 | bits of this expression. | |
4404 | ||
93b45514 | 4405 | @item value |
b50e59fe | 4406 | An absolute expression which becomes the symbol's value. |
93b45514 RP |
4407 | @end table |
4408 | ||
b50e59fe | 4409 | If a warning is detected while reading a @code{.stabd}, @code{.stabn}, |
05a0e43b RP |
4410 | or @code{.stabs} statement, the symbol has probably already been created; |
4411 | you get a half-formed symbol in your object file. This is | |
b50e59fe | 4412 | compatible with earlier assemblers! |
93b45514 | 4413 | |
47342e8f | 4414 | @table @code |
66b818fb | 4415 | @cindex @code{stabd} directive |
47342e8f | 4416 | @item .stabd @var{type} , @var{other} , @var{desc} |
93b45514 RP |
4417 | |
4418 | The ``name'' of the symbol generated is not even an empty string. | |
4419 | It is a null pointer, for compatibility. Older assemblers used a | |
4420 | null pointer so they didn't waste space in object files with empty | |
4421 | strings. | |
4422 | ||
b50e59fe | 4423 | The symbol's value is set to the location counter, |
93b45514 | 4424 | relocatably. When your program is linked, the value of this symbol |
05a0e43b | 4425 | is the address of the location counter when the @code{.stabd} was |
93b45514 RP |
4426 | assembled. |
4427 | ||
66b818fb | 4428 | @cindex @code{stabn} directive |
71dd3c40 | 4429 | @item .stabn @var{type} , @var{other} , @var{desc} , @var{value} |
93b45514 RP |
4430 | The name of the symbol is set to the empty string @code{""}. |
4431 | ||
66b818fb | 4432 | @cindex @code{stabs} directive |
71dd3c40 | 4433 | @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value} |
47342e8f RP |
4434 | All five fields are specified. |
4435 | @end table | |
f009d0ab RP |
4436 | @end ifset |
4437 | @c end have-stabs | |
d0281557 | 4438 | |
e680d737 RP |
4439 | @node String |
4440 | @section @code{.string} "@var{str}" | |
4441 | ||
4442 | @cindex string, copying to object file | |
4443 | @cindex @code{string} directive | |
4444 | ||
4445 | Copy the characters in @var{str} to the object file. You may specify more than | |
4446 | one string to copy, separated by commas. Unless otherwise specified for a | |
4447 | particular machine, the assembler marks the end of each string with a 0 byte. | |
81fcb3ff | 4448 | You can use any of the escape sequences described in @ref{Strings,,Strings}. |
e680d737 | 4449 | |
35cfacf0 ILT |
4450 | @ifset ELF |
4451 | @node Symver | |
4452 | @section @code{.symver} | |
4453 | @cindex @code{symver} directive | |
4454 | @cindex symbol versioning | |
4455 | @cindex versions of symbols | |
4456 | Use the @code{.symver} directive to bind symbols to specific version nodes | |
4457 | within a source file. This is only supported on ELF platforms, and is | |
4458 | typically used when assembling files to be linked into a shared library. | |
4459 | There are cases where it may make sense to use this in objects to be bound | |
4460 | into an application itself so as to override a versioned symbol from a | |
4461 | shared library. | |
4462 | ||
4463 | For ELF targets, the @code{.symver} directive is used like this: | |
4464 | @smallexample | |
4465 | .symver @var{name}, @var{name2@@nodename} | |
4466 | @end smallexample | |
4467 | In this case, the symbol @var{name} must exist and be defined within the file | |
4468 | being assembled. The @code{.versym} directive effectively creates a symbol | |
4469 | alias with the name @var{name2@@nodename}, and in fact the main reason that we | |
4470 | just don't try and create a regular alias is that the @var{@@} character isn't | |
4471 | permitted in symbol names. The @var{name2} part of the name is the actual name | |
4472 | of the symbol by which it will be externally referenced. The name @var{name} | |
4473 | itself is merely a name of convenience that is used so that it is possible to | |
4474 | have definitions for multiple versions of a function within a single source | |
4475 | file, and so that the compiler can unambiguously know which version of a | |
4476 | function is being mentioned. The @var{nodename} portion of the alias should be | |
4477 | the name of a node specified in the version script supplied to the linker when | |
4478 | building a shared library. If you are attempting to override a versioned | |
4479 | symbol from a shared library, then @var{nodename} should correspond to the | |
4480 | nodename of the symbol you are trying to override. | |
4481 | @end ifset | |
4482 | ||
f009d0ab | 4483 | @ifset COFF |
242d9c06 | 4484 | @node Tag |
d0281557 | 4485 | @section @code{.tag @var{structname}} |
66b818fb RP |
4486 | |
4487 | @cindex COFF structure debugging | |
4488 | @cindex structure debugging, COFF | |
4489 | @cindex @code{tag} directive | |
d0281557 RP |
4490 | This directive is generated by compilers to include auxiliary debugging |
4491 | information in the symbol table. It is only permitted inside | |
4492 | @code{.def}/@code{.endef} pairs. Tags are used to link structure | |
4493 | definitions in the symbol table with instances of those structures. | |
f009d0ab | 4494 | @ifset BOUT |
d0281557 RP |
4495 | |
4496 | @samp{.tag} is only used when generating COFF format output; when | |
f009d0ab | 4497 | @code{@value{AS}} is generating @code{b.out}, it accepts this directive but |
d0281557 | 4498 | ignores it. |
f009d0ab RP |
4499 | @end ifset |
4500 | @end ifset | |
7a4c8e5c | 4501 | |
242d9c06 | 4502 | @node Text |
24b1493d | 4503 | @section @code{.text @var{subsection}} |
66b818fb RP |
4504 | |
4505 | @cindex @code{text} directive | |
f009d0ab | 4506 | Tells @code{@value{AS}} to assemble the following statements onto the end of |
24b1493d RP |
4507 | the text subsection numbered @var{subsection}, which is an absolute |
4508 | expression. If @var{subsection} is omitted, subsection number zero | |
93b45514 RP |
4509 | is used. |
4510 | ||
242d9c06 | 4511 | @node Title |
66b818fb RP |
4512 | @section @code{.title "@var{heading}"} |
4513 | ||
4514 | @cindex @code{title} directive | |
4515 | @cindex listing control: title line | |
4516 | Use @var{heading} as the title (second line, immediately after the | |
f009d0ab | 4517 | source file name and pagenumber) when generating assembly listings. |
66b818fb RP |
4518 | |
4519 | This directive affects subsequent pages, as well as the current page if | |
4520 | it appears within ten lines of the top of a page. | |
4521 | ||
f009d0ab | 4522 | @ifset COFF |
242d9c06 | 4523 | @node Type |
d0281557 | 4524 | @section @code{.type @var{int}} |
66b818fb RP |
4525 | |
4526 | @cindex COFF symbol type | |
4527 | @cindex symbol type, COFF | |
4528 | @cindex @code{type} directive | |
d0281557 RP |
4529 | This directive, permitted only within @code{.def}/@code{.endef} pairs, |
4530 | records the integer @var{int} as the type attribute of a symbol table entry. | |
f009d0ab | 4531 | @ifset BOUT |
d0281557 RP |
4532 | |
4533 | @samp{.type} is associated only with COFF format output; when | |
f009d0ab | 4534 | @code{@value{AS}} is configured for @code{b.out} output, it accepts this |
d0281557 | 4535 | directive but ignores it. |
f009d0ab RP |
4536 | @end ifset |
4537 | @end ifset | |
d0281557 | 4538 | |
f009d0ab | 4539 | @ifset COFF |
242d9c06 | 4540 | @node Val |
d0281557 | 4541 | @section @code{.val @var{addr}} |
66b818fb RP |
4542 | |
4543 | @cindex @code{val} directive | |
4544 | @cindex COFF value attribute | |
4545 | @cindex value attribute, COFF | |
d0281557 RP |
4546 | This directive, permitted only within @code{.def}/@code{.endef} pairs, |
4547 | records the address @var{addr} as the value attribute of a symbol table | |
4548 | entry. | |
f009d0ab | 4549 | @ifset BOUT |
d0281557 | 4550 | |
f009d0ab | 4551 | @samp{.val} is used only for COFF output; when @code{@value{AS}} is |
d0281557 | 4552 | configured for @code{b.out}, it accepts this directive but ignores it. |
f009d0ab RP |
4553 | @end ifset |
4554 | @end ifset | |
7a4c8e5c | 4555 | |
3ffb03b1 DE |
4556 | @node Uleb128 |
4557 | @section @code{.uleb128 @var{expressions}} | |
4558 | ||
4559 | @cindex @code{uleb128} directive | |
4560 | @var{uleb128} stands for ``unsigned little endian base 128.'' This is a | |
4561 | compact, variable length representation of numbers used by the DWARF | |
4562 | symbolic debugging format. @xref{Sleb128,@code{.sleb128}}. | |
4563 | ||
242d9c06 | 4564 | @node Word |
b50e59fe | 4565 | @section @code{.word @var{expressions}} |
66b818fb RP |
4566 | |
4567 | @cindex @code{word} directive | |
24b1493d | 4568 | This directive expects zero or more @var{expressions}, of any section, |
b50e59fe | 4569 | separated by commas. |
f009d0ab RP |
4570 | @ifclear GENERIC |
4571 | @ifset W32 | |
4572 | For each expression, @code{@value{AS}} emits a 32-bit number. | |
4573 | @end ifset | |
4574 | @ifset W16 | |
4575 | For each expression, @code{@value{AS}} emits a 16-bit number. | |
4576 | @end ifset | |
4577 | @end ifclear | |
4578 | @ifset GENERIC | |
4579 | ||
0b5b143a | 4580 | The size of the number emitted, and its byte order, |
05a0e43b | 4581 | depend on what target computer the assembly is for. |
f009d0ab | 4582 | @end ifset |
09352a5d | 4583 | |
7a4c8e5c | 4584 | @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't |
09352a5d | 4585 | @c happen---32-bit addressability, period; no long/short jumps. |
f009d0ab | 4586 | @ifset DIFF-TBL-KLUGE |
66b818fb RP |
4587 | @cindex difference tables altered |
4588 | @cindex altered difference tables | |
0b5b143a RP |
4589 | @quotation |
4590 | @emph{Warning: Special Treatment to support Compilers} | |
4591 | @end quotation | |
47342e8f | 4592 | |
f009d0ab | 4593 | @ifset GENERIC |
24b1493d RP |
4594 | Machines with a 32-bit address space, but that do less than 32-bit |
4595 | addressing, require the following special treatment. If the machine of | |
4596 | interest to you does 32-bit addressing (or doesn't require it; | |
f009d0ab | 4597 | @pxref{Machine Dependencies}), you can ignore this issue. |
7a4c8e5c | 4598 | |
f009d0ab | 4599 | @end ifset |
05a0e43b RP |
4600 | In order to assemble compiler output into something that works, |
4601 | @code{@value{AS}} occasionlly does strange things to @samp{.word} directives. | |
47342e8f | 4602 | Directives of the form @samp{.word sym1-sym2} are often emitted by |
f009d0ab | 4603 | compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a |
47342e8f | 4604 | directive of the form @samp{.word sym1-sym2}, and the difference between |
05a0e43b RP |
4605 | @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}} |
4606 | creates a @dfn{secondary jump table}, immediately before the next label. | |
4607 | This secondary jump table is preceded by a short-jump to the | |
47342e8f RP |
4608 | first byte after the secondary table. This short-jump prevents the flow |
4609 | of control from accidentally falling into the new table. Inside the | |
05a0e43b RP |
4610 | table is a long-jump to @code{sym2}. The original @samp{.word} |
4611 | contains @code{sym1} minus the address of the long-jump to | |
d0281557 | 4612 | @code{sym2}. |
47342e8f RP |
4613 | |
4614 | If there were several occurrences of @samp{.word sym1-sym2} before the | |
05a0e43b | 4615 | secondary jump table, all of them are adjusted. If there was a |
47342e8f | 4616 | @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a |
05a0e43b RP |
4617 | long-jump to @code{sym4} is included in the secondary jump table, |
4618 | and the @code{.word} directives are adjusted to contain @code{sym3} | |
47342e8f | 4619 | minus the address of the long-jump to @code{sym4}; and so on, for as many |
d0281557 | 4620 | entries in the original jump table as necessary. |
09352a5d | 4621 | |
f009d0ab RP |
4622 | @ifset INTERNALS |
4623 | @emph{This feature may be disabled by compiling @code{@value{AS}} with the | |
47342e8f RP |
4624 | @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse |
4625 | assembly language programmers. | |
f009d0ab RP |
4626 | @end ifset |
4627 | @end ifset | |
4628 | @c end DIFF-TBL-KLUGE | |
93b45514 | 4629 | |
242d9c06 | 4630 | @node Deprecated |
93b45514 | 4631 | @section Deprecated Directives |
66b818fb RP |
4632 | |
4633 | @cindex deprecated directives | |
4634 | @cindex obsolescent directives | |
93b45514 RP |
4635 | One day these directives won't work. |
4636 | They are included for compatibility with older assemblers. | |
4637 | @table @t | |
4638 | @item .abort | |
2d8e0f62 | 4639 | @item .app-file |
93b45514 RP |
4640 | @item .line |
4641 | @end table | |
4642 | ||
f009d0ab RP |
4643 | @ifset GENERIC |
4644 | @node Machine Dependencies | |
09352a5d | 4645 | @chapter Machine Dependent Features |
66b818fb RP |
4646 | |
4647 | @cindex machine dependencies | |
4648 | The machine instruction sets are (almost by definition) different on | |
f009d0ab RP |
4649 | each machine where @code{@value{AS}} runs. Floating point representations |
4650 | vary as well, and @code{@value{AS}} often supports a few additional | |
66b818fb RP |
4651 | directives or command-line options for compatibility with other |
4652 | assemblers on a particular platform. Finally, some versions of | |
f009d0ab | 4653 | @code{@value{AS}} support special pseudo-instructions for branch |
66b818fb RP |
4654 | optimization. |
4655 | ||
4656 | This chapter discusses most of these differences, though it does not | |
4657 | include details on any machine's instruction set. For details on that | |
4658 | subject, see the hardware manufacturer's manual. | |
4659 | ||
7a4c8e5c | 4660 | @menu |
910d7df2 C |
4661 | @ifset A29K |
4662 | * AMD29K-Dependent:: AMD 29K Dependent Features | |
4663 | @end ifset | |
99c4053d KR |
4664 | @ifset ARC |
4665 | * ARC-Dependent:: ARC Dependent Features | |
4666 | @end ifset | |
3ffb03b1 DE |
4667 | @ifset ARM |
4668 | * ARM-Dependent:: ARM Dependent Features | |
4669 | @end ifset | |
9a5acea8 ILT |
4670 | @ifset D10V |
4671 | * D10V-Dependent:: D10V Dependent Features | |
4672 | @end ifset | |
f009d0ab | 4673 | @ifset H8/300 |
ba487f3a | 4674 | * H8/300-Dependent:: Hitachi H8/300 Dependent Features |
f009d0ab RP |
4675 | @end ifset |
4676 | @ifset H8/500 | |
4677 | * H8/500-Dependent:: Hitachi H8/500 Dependent Features | |
4678 | @end ifset | |
9dcf8057 | 4679 | @ifset HPPA |
fb5bec49 | 4680 | * HPPA-Dependent:: HPPA Dependent Features |
9dcf8057 | 4681 | @end ifset |
910d7df2 C |
4682 | @ifset I80386 |
4683 | * i386-Dependent:: Intel 80386 Dependent Features | |
f009d0ab | 4684 | @end ifset |
f009d0ab | 4685 | @ifset I960 |
ba487f3a | 4686 | * i960-Dependent:: Intel 80960 Dependent Features |
f009d0ab | 4687 | @end ifset |
ee73be40 NC |
4688 | @ifset M32R |
4689 | * M32R-Dependent:: M32R Dependent Features | |
4690 | @end ifset | |
f009d0ab | 4691 | @ifset M680X0 |
ba487f3a | 4692 | * M68K-Dependent:: M680x0 Dependent Features |
f009d0ab | 4693 | @end ifset |
910d7df2 C |
4694 | @ifset MIPS |
4695 | * MIPS-Dependent:: MIPS Dependent Features | |
4696 | @end ifset | |
4697 | @ifset SH | |
4698 | * SH-Dependent:: Hitachi SH Dependent Features | |
4699 | @end ifset | |
f009d0ab | 4700 | @ifset SPARC |
ba487f3a | 4701 | * Sparc-Dependent:: SPARC Dependent Features |
f009d0ab | 4702 | @end ifset |
11959ebc ILT |
4703 | @ifset V850 |
4704 | * V850-Dependent:: V850 Dependent Features | |
4705 | @end ifset | |
f009d0ab | 4706 | @ifset Z8000 |
ba487f3a | 4707 | * Z8000-Dependent:: Z8000 Dependent Features |
f009d0ab | 4708 | @end ifset |
910d7df2 C |
4709 | @ifset VAX |
4710 | * Vax-Dependent:: VAX Dependent Features | |
f009d0ab | 4711 | @end ifset |
7a4c8e5c RP |
4712 | @end menu |
4713 | ||
9dcf8057 | 4714 | @lowersections |
f009d0ab RP |
4715 | @end ifset |
4716 | ||
4717 | @c The following major nodes are *sections* in the GENERIC version, *chapters* | |
9dcf8057 | 4718 | @c in single-cpu versions. This is mainly achieved by @lowersections. There is a |
f009d0ab RP |
4719 | @c peculiarity: to preserve cross-references, there must be a node called |
4720 | @c "Machine Dependencies". Hence the conditional nodenames in each | |
4721 | @c major node below. Node defaulting in makeinfo requires adjacency of | |
4722 | @c node and sectioning commands; hence the repetition of @chapter BLAH | |
4723 | @c in both conditional blocks. | |
99c4053d | 4724 | |
99c4053d KR |
4725 | @ifset ARC |
4726 | @ifset GENERIC | |
4727 | @page | |
4728 | @node ARC-Dependent | |
4729 | @chapter ARC Dependent Features | |
4730 | @end ifset | |
4731 | @ifclear GENERIC | |
4732 | @node Machine Dependencies | |
4733 | @chapter ARC Dependent Features | |
4734 | @end ifclear | |
4735 | ||
4736 | @cindex ARC support | |
4737 | @menu | |
4738 | * ARC-Opts:: Options | |
4739 | * ARC-Float:: Floating Point | |
4740 | * ARC-Directives:: Sparc Machine Directives | |
4741 | @end menu | |
4742 | ||
4743 | @node ARC-Opts | |
4744 | @section Options | |
4745 | ||
4746 | @cindex options for ARC | |
4747 | @cindex ARC options | |
4748 | @cindex architectures, ARC | |
4749 | @cindex ARC architectures | |
4750 | The ARC chip family includes several successive levels (or other | |
4751 | variants) of chip, using the same core instruction set, but including | |
4752 | a few additional instructions at each level. | |
4753 | ||
4754 | By default, @code{@value{AS}} assumes the core instruction set (ARC | |
3ffb03b1 DE |
4755 | base). The @code{.cpu} pseudo-op is intended to be used to select |
4756 | the variant. | |
99c4053d KR |
4757 | |
4758 | @table @code | |
4759 | @cindex @code{-mbig-endian} option (ARC) | |
4760 | @cindex @code{-mlittle-endian} option (ARC) | |
4761 | @cindex ARC big-endian output | |
4762 | @cindex ARC little-endian output | |
4763 | @cindex big-endian output, ARC | |
4764 | @cindex little-endian output, ARC | |
4765 | @item -mbig-endian | |
4766 | @itemx -mlittle-endian | |
4767 | Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or | |
4768 | little-endian output at run time (unlike most other @sc{gnu} development | |
4769 | tools, which must be configured for one or the other). Use | |
4770 | @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian} | |
4771 | for little-endian. | |
4772 | @end table | |
4773 | ||
4774 | @node ARC-Float | |
4775 | @section Floating Point | |
4776 | ||
4777 | @cindex floating point, ARC (@sc{ieee}) | |
4778 | @cindex ARC floating point (@sc{ieee}) | |
4779 | The ARC cpu family currently does not have hardware floating point | |
4780 | support. Software floating point support is provided by @code{GCC} | |
4781 | and uses @sc{ieee} floating-point numbers. | |
4782 | ||
4783 | @node ARC-Directives | |
4784 | @section ARC Machine Directives | |
4785 | ||
4786 | @cindex ARC machine directives | |
4787 | @cindex machine directives, ARC | |
4788 | The ARC version of @code{@value{AS}} supports the following additional | |
4789 | machine directives: | |
4790 | ||
4791 | @table @code | |
4792 | @item .cpu | |
4793 | @cindex @code{cpu} directive, SPARC | |
3ffb03b1 DE |
4794 | This must be followed by the desired cpu. |
4795 | The ARC is intended to be customizable, @code{.cpu} is used to | |
4796 | select the desired variant [though currently there are none]. | |
99c4053d KR |
4797 | |
4798 | @end table | |
4799 | ||
4800 | @end ifset | |
99c4053d | 4801 | |
f009d0ab | 4802 | @ifset A29K |
79e15b8a | 4803 | @include c-a29k.texi |
f009d0ab | 4804 | @end ifset |
b50e59fe | 4805 | |
3ffb03b1 DE |
4806 | @ifset ARM |
4807 | @include c-arm.texi | |
4808 | @end ifset | |
4809 | ||
f009d0ab RP |
4810 | @ifset Hitachi-all |
4811 | @ifclear GENERIC | |
4812 | @node Machine Dependencies | |
4813 | @chapter Machine Dependent Features | |
4814 | ||
4815 | The machine instruction sets are different on each Hitachi chip family, | |
4816 | and there are also some syntax differences among the families. This | |
4817 | chapter describes the specific @code{@value{AS}} features for each | |
4818 | family. | |
4819 | ||
4820 | @menu | |
4821 | * H8/300-Dependent:: Hitachi H8/300 Dependent Features | |
4822 | * H8/500-Dependent:: Hitachi H8/500 Dependent Features | |
f009d0ab | 4823 | * SH-Dependent:: Hitachi SH Dependent Features |
f009d0ab | 4824 | @end menu |
9dcf8057 | 4825 | @lowersections |
f009d0ab RP |
4826 | @end ifclear |
4827 | @end ifset | |
4828 | ||
9a5acea8 ILT |
4829 | @ifset D10V |
4830 | @include c-d10v.texi | |
4831 | @end ifset | |
9a5acea8 | 4832 | |
f009d0ab | 4833 | @ifset H8/300 |
79e15b8a | 4834 | @include c-h8300.texi |
f009d0ab | 4835 | @end ifset |
24b1493d | 4836 | |
79e15b8a ILT |
4837 | @ifset H8/500 |
4838 | @include c-h8500.texi | |
fb5bec49 | 4839 | @end ifset |
66b818fb | 4840 | |
79e15b8a ILT |
4841 | @ifset HPPA |
4842 | @include c-hppa.texi | |
4843 | @end ifset | |
66b818fb | 4844 | |
910d7df2 C |
4845 | @ifset I80386 |
4846 | @include c-i386.texi | |
79e15b8a | 4847 | @end ifset |
66b818fb | 4848 | |
79e15b8a ILT |
4849 | @ifset I960 |
4850 | @include c-i960.texi | |
f009d0ab RP |
4851 | @end ifset |
4852 | ||
ee73be40 NC |
4853 | @ifset M32R |
4854 | @include c-m32r.texi | |
4855 | @end ifset | |
4856 | ||
79e15b8a ILT |
4857 | @ifset M680X0 |
4858 | @include c-m68k.texi | |
4859 | @end ifset | |
f009d0ab | 4860 | |
910d7df2 C |
4861 | @ifset MIPS |
4862 | @include c-mips.texi | |
4863 | @end ifset | |
4864 | ||
71dd3c40 ILT |
4865 | @ifset NS32K |
4866 | @include c-ns32k.texi | |
4867 | @end ifset | |
f009d0ab | 4868 | |
910d7df2 C |
4869 | @ifset SH |
4870 | @include c-sh.texi | |
79e15b8a | 4871 | @end ifset |
f009d0ab | 4872 | |
910d7df2 C |
4873 | @ifset SPARC |
4874 | @include c-sparc.texi | |
79e15b8a | 4875 | @end ifset |
fb5bec49 | 4876 | |
79e15b8a ILT |
4877 | @ifset Z8000 |
4878 | @include c-z8k.texi | |
4879 | @end ifset | |
34214344 | 4880 | |
910d7df2 C |
4881 | @ifset VAX |
4882 | @include c-vax.texi | |
34214344 KR |
4883 | @end ifset |
4884 | ||
68eaa141 NC |
4885 | @ifset V850 |
4886 | @include c-v850.texi | |
4887 | @end ifset | |
68eaa141 | 4888 | |
f009d0ab RP |
4889 | @ifset GENERIC |
4890 | @c reverse effect of @down at top of generic Machine-Dep chapter | |
9dcf8057 | 4891 | @raisesections |
f009d0ab RP |
4892 | @end ifset |
4893 | ||
9a5acea8 ILT |
4894 | @node Reporting Bugs |
4895 | @chapter Reporting Bugs | |
3ffb03b1 DE |
4896 | @cindex bugs in assembler |
4897 | @cindex reporting bugs in assembler | |
9a5acea8 ILT |
4898 | |
4899 | Your bug reports play an essential role in making @code{@value{AS}} reliable. | |
4900 | ||
4901 | Reporting a bug may help you by bringing a solution to your problem, or it may | |
4902 | not. But in any case the principal function of a bug report is to help the | |
4903 | entire community by making the next version of @code{@value{AS}} work better. | |
4904 | Bug reports are your contribution to the maintenance of @code{@value{AS}}. | |
4905 | ||
4906 | In order for a bug report to serve its purpose, you must include the | |
4907 | information that enables us to fix the bug. | |
4908 | ||
4909 | @menu | |
4910 | * Bug Criteria:: Have you found a bug? | |
4911 | * Bug Reporting:: How to report bugs | |
4912 | @end menu | |
4913 | ||
4914 | @node Bug Criteria | |
4915 | @section Have you found a bug? | |
4916 | @cindex bug criteria | |
4917 | ||
4918 | If you are not sure whether you have found a bug, here are some guidelines: | |
4919 | ||
4920 | @itemize @bullet | |
4921 | @cindex fatal signal | |
4922 | @cindex assembler crash | |
4923 | @cindex crash of assembler | |
4924 | @item | |
4925 | If the assembler gets a fatal signal, for any input whatever, that is a | |
4926 | @code{@value{AS}} bug. Reliable assemblers never crash. | |
4927 | ||
4928 | @cindex error on valid input | |
4929 | @item | |
4930 | If @code{@value{AS}} produces an error message for valid input, that is a bug. | |
4931 | ||
4932 | @cindex invalid input | |
4933 | @item | |
4934 | If @code{@value{AS}} does not produce an error message for invalid input, that | |
4935 | is a bug. However, you should note that your idea of ``invalid input'' might | |
4936 | be our idea of ``an extension'' or ``support for traditional practice''. | |
4937 | ||
4938 | @item | |
4939 | If you are an experienced user of assemblers, your suggestions for improvement | |
4940 | of @code{@value{AS}} are welcome in any case. | |
4941 | @end itemize | |
4942 | ||
4943 | @node Bug Reporting | |
4944 | @section How to report bugs | |
4945 | @cindex bug reports | |
3ffb03b1 | 4946 | @cindex assembler bugs, reporting |
9a5acea8 ILT |
4947 | |
4948 | A number of companies and individuals offer support for @sc{gnu} products. If | |
4949 | you obtained @code{@value{AS}} from a support organization, we recommend you | |
4950 | contact that organization first. | |
4951 | ||
4952 | You can find contact information for many support companies and | |
4953 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
4954 | distribution. | |
4955 | ||
4956 | In any event, we also recommend that you send bug reports for @code{@value{AS}} | |
4957 | to @samp{bug-gnu-utils@@prep.ai.mit.edu}. | |
4958 | ||
4959 | The fundamental principle of reporting bugs usefully is this: | |
4960 | @strong{report all the facts}. If you are not sure whether to state a | |
4961 | fact or leave it out, state it! | |
4962 | ||
4963 | Often people omit facts because they think they know what causes the problem | |
4964 | and assume that some details do not matter. Thus, you might assume that the | |
4965 | name of a symbol you use in an example does not matter. Well, probably it does | |
4966 | not, but one cannot be sure. Perhaps the bug is a stray memory reference which | |
4967 | happens to fetch from the location where that name is stored in memory; | |
4968 | perhaps, if the name were different, the contents of that location would fool | |
4969 | the assembler into doing the right thing despite the bug. Play it safe and | |
4970 | give a specific, complete example. That is the easiest thing for you to do, | |
4971 | and the most helpful. | |
4972 | ||
4973 | Keep in mind that the purpose of a bug report is to enable us to fix the bug if | |
4974 | it is new to us. Therefore, always write your bug reports on the assumption | |
4975 | that the bug has not been reported previously. | |
4976 | ||
4977 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
4978 | bell?'' Those bug reports are useless, and we urge everyone to | |
4979 | @emph{refuse to respond to them} except to chide the sender to report | |
4980 | bugs properly. | |
4981 | ||
4982 | To enable us to fix the bug, you should include all these things: | |
4983 | ||
4984 | @itemize @bullet | |
4985 | @item | |
4986 | The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start | |
868c3513 | 4987 | it with the @samp{--version} argument. |
9a5acea8 ILT |
4988 | |
4989 | Without this, we will not know whether there is any point in looking for | |
4990 | the bug in the current version of @code{@value{AS}}. | |
4991 | ||
4992 | @item | |
4993 | Any patches you may have applied to the @code{@value{AS}} source. | |
4994 | ||
4995 | @item | |
4996 | The type of machine you are using, and the operating system name and | |
4997 | version number. | |
4998 | ||
4999 | @item | |
5000 | What compiler (and its version) was used to compile @code{@value{AS}}---e.g. | |
5001 | ``@code{gcc-2.7}''. | |
5002 | ||
5003 | @item | |
5004 | The command arguments you gave the assembler to assemble your example and | |
5005 | observe the bug. To guarantee you will not omit something important, list them | |
5006 | all. A copy of the Makefile (or the output from make) is sufficient. | |
5007 | ||
5008 | If we were to try to guess the arguments, we would probably guess wrong | |
5009 | and then we might not encounter the bug. | |
5010 | ||
5011 | @item | |
5012 | A complete input file that will reproduce the bug. If the bug is observed when | |
5013 | the assembler is invoked via a compiler, send the assembler source, not the | |
5014 | high level language source. Most compilers will produce the assembler source | |
5015 | when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use | |
5016 | the options @samp{-v --save-temps}; this will save the assembler source in a | |
5017 | file with an extension of @file{.s}, and also show you exactly how | |
5018 | @code{@value{AS}} is being run. | |
5019 | ||
5020 | @item | |
5021 | A description of what behavior you observe that you believe is | |
5022 | incorrect. For example, ``It gets a fatal signal.'' | |
5023 | ||
5024 | Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we | |
5025 | will certainly notice it. But if the bug is incorrect output, we might not | |
5026 | notice unless it is glaringly wrong. You might as well not give us a chance to | |
5027 | make a mistake. | |
5028 | ||
5029 | Even if the problem you experience is a fatal signal, you should still say so | |
5030 | explicitly. Suppose something strange is going on, such as, your copy of | |
5031 | @code{@value{AS}} is out of synch, or you have encountered a bug in the C | |
5032 | library on your system. (This has happened!) Your copy might crash and ours | |
5033 | would not. If you told us to expect a crash, then when ours fails to crash, we | |
5034 | would know that the bug was not happening for us. If you had not told us to | |
5035 | expect a crash, then we would not be able to draw any conclusion from our | |
5036 | observations. | |
5037 | ||
5038 | @item | |
5039 | If you wish to suggest changes to the @code{@value{AS}} source, send us context | |
5040 | diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p} | |
5041 | option. Always send diffs from the old file to the new file. If you even | |
5042 | discuss something in the @code{@value{AS}} source, refer to it by context, not | |
5043 | by line number. | |
5044 | ||
5045 | The line numbers in our development sources will not match those in your | |
5046 | sources. Your line numbers would convey no useful information to us. | |
5047 | @end itemize | |
5048 | ||
5049 | Here are some things that are not necessary: | |
5050 | ||
5051 | @itemize @bullet | |
5052 | @item | |
5053 | A description of the envelope of the bug. | |
5054 | ||
5055 | Often people who encounter a bug spend a lot of time investigating | |
5056 | which changes to the input file will make the bug go away and which | |
5057 | changes will not affect it. | |
5058 | ||
5059 | This is often time consuming and not very useful, because the way we | |
5060 | will find the bug is by running a single example under the debugger | |
5061 | with breakpoints, not by pure deduction from a series of examples. | |
5062 | We recommend that you save your time for something else. | |
5063 | ||
5064 | Of course, if you can find a simpler example to report @emph{instead} | |
5065 | of the original one, that is a convenience for us. Errors in the | |
5066 | output will be easier to spot, running under the debugger will take | |
5067 | less time, and so on. | |
5068 | ||
5069 | However, simplification is not vital; if you do not want to do this, | |
5070 | report the bug anyway and send us the entire test case you used. | |
5071 | ||
5072 | @item | |
5073 | A patch for the bug. | |
5074 | ||
5075 | A patch for the bug does help us if it is a good one. But do not omit | |
5076 | the necessary information, such as the test case, on the assumption that | |
5077 | a patch is all we need. We might see problems with your patch and decide | |
5078 | to fix the problem another way, or we might not understand it at all. | |
5079 | ||
5080 | Sometimes with a program as complicated as @code{@value{AS}} it is very hard to | |
5081 | construct an example that will make the program follow a certain path through | |
5082 | the code. If you do not send us the example, we will not be able to construct | |
5083 | one, so we will not be able to verify that the bug is fixed. | |
5084 | ||
5085 | And if we cannot understand what bug you are trying to fix, or why your | |
5086 | patch should be an improvement, we will not install it. A test case will | |
5087 | help us to understand. | |
5088 | ||
5089 | @item | |
5090 | A guess about what the bug is or what it depends on. | |
5091 | ||
5092 | Such guesses are usually wrong. Even we cannot guess right about such | |
5093 | things without first using the debugger to find the facts. | |
5094 | @end itemize | |
5095 | ||
9dcf8057 JL |
5096 | @node Acknowledgements |
5097 | @chapter Acknowledgements | |
5098 | ||
05a0e43b RP |
5099 | If you have contributed to @code{@value{AS}} and your name isn't listed here, |
5100 | it is not meant as a slight. We just don't know about it. Send mail to the | |
71dd3c40 ILT |
5101 | maintainer, and we'll correct the situation. Currently |
5102 | @c (January 1994), | |
5103 | the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}). | |
9dcf8057 | 5104 | |
79e15b8a ILT |
5105 | Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any |
5106 | more details?} | |
9dcf8057 | 5107 | |
05a0e43b | 5108 | Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug |
9dcf8057 | 5109 | information and the 68k series machines, most of the preprocessing pass, and |
05a0e43b | 5110 | extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}. |
9dcf8057 JL |
5111 | |
5112 | K. Richard Pixley maintained GAS for a while, adding various enhancements and | |
5113 | many bug fixes, including merging support for several processors, breaking GAS | |
05a0e43b RP |
5114 | up to handle multiple object file format back ends (including heavy rewrite, |
5115 | testing, an integration of the coff and b.out back ends), adding configuration | |
9dcf8057 | 5116 | including heavy testing and verification of cross assemblers and file splits |
05a0e43b RP |
5117 | and renaming, converted GAS to strictly ANSI C including full prototypes, added |
5118 | support for m680[34]0 and cpu32, did considerable work on i960 including a COFF | |
5119 | port (including considerable amounts of reverse engineering), a SPARC opcode | |
5120 | file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know'' | |
9dcf8057 JL |
5121 | assertions and made them work, much other reorganization, cleanup, and lint. |
5122 | ||
5123 | Ken Raeburn wrote the high-level BFD interface code to replace most of the code | |
5124 | in format-specific I/O modules. | |
5125 | ||
5126 | The original VMS support was contributed by David L. Kashtan. Eric Youngdale | |
5127 | has done much work with it since. | |
5128 | ||
5129 | The Intel 80386 machine description was written by Eliot Dresselhaus. | |
5130 | ||
5131 | Minh Tran-Le at IntelliCorp contributed some AIX 386 support. | |
5132 | ||
5133 | The Motorola 88k machine description was contributed by Devon Bowen of Buffalo | |
5134 | University and Torbjorn Granlund of the Swedish Institute of Computer Science. | |
5135 | ||
5136 | Keith Knowles at the Open Software Foundation wrote the original MIPS back end | |
05a0e43b RP |
5137 | (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support |
5138 | (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to | |
5139 | support a.out format. | |
9dcf8057 JL |
5140 | |
5141 | Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k, | |
5142 | tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by | |
5143 | Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to | |
5144 | use BFD for some low-level operations, for use with the H8/300 and AMD 29k | |
5145 | targets. | |
5146 | ||
05a0e43b RP |
5147 | John Gilmore built the AMD 29000 support, added @code{.include} support, and |
5148 | simplified the configuration of which versions accept which directives. He | |
9dcf8057 | 5149 | updated the 68k machine description so that Motorola's opcodes always produced |
05a0e43b RP |
5150 | fixed-size instructions (e.g. @code{jsr}), while synthetic instructions |
5151 | remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested | |
9dcf8057 | 5152 | cross-compilation support, and one bug in relaxation that took a week and |
47c7ceb5 | 5153 | required the proverbial one-bit fix. |
9dcf8057 | 5154 | |
05a0e43b | 5155 | Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the |
9dcf8057 | 5156 | 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), |
910d7df2 C |
5157 | added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and |
5158 | PowerPC assembler, and made a few other minor patches. | |
9dcf8057 JL |
5159 | |
5160 | Steve Chamberlain made @code{@value{AS}} able to generate listings. | |
5161 | ||
05a0e43b | 5162 | Hewlett-Packard contributed support for the HP9000/300. |
9dcf8057 | 5163 | |
05a0e43b RP |
5164 | Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) |
5165 | along with a fairly extensive HPPA testsuite (for both SOM and ELF object | |
5166 | formats). This work was supported by both the Center for Software Science at | |
5167 | the University of Utah and Cygnus Support. | |
9dcf8057 JL |
5168 | |
5169 | Support for ELF format files has been worked on by Mark Eichin of Cygnus | |
5170 | Support (original, incomplete implementation for SPARC), Pete Hoogenboom and | |
5171 | Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open | |
5172 | Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, | |
5173 | and some initial 64-bit support). | |
5174 | ||
8a51eeaf TT |
5175 | Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD |
5176 | support for openVMS/Alpha. | |
910d7df2 | 5177 | |
9dcf8057 JL |
5178 | Several engineers at Cygnus Support have also provided many small bug fixes and |
5179 | configuration enhancements. | |
5180 | ||
5181 | Many others have contributed large or small bugfixes and enhancements. If | |
05a0e43b RP |
5182 | you have contributed significant work and are not mentioned on this list, and |
5183 | want to be, let us know. Some of the history has been lost; we are not | |
9dcf8057 JL |
5184 | intentionally leaving anyone out. |
5185 | ||
242d9c06 | 5186 | @node Index |
66b818fb RP |
5187 | @unnumbered Index |
5188 | ||
5189 | @printindex cp | |
5190 | ||
93b45514 RP |
5191 | @contents |
5192 | @bye | |
9dcf8057 JL |
5193 | @c Local Variables: |
5194 | @c fill-column: 79 | |
5195 | @c End: |