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