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[mLib] / crc-mktab.c
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b7580524 1/* -*-c-*-
2 *
0521f473 3 * $Id: crc-mktab.c,v 1.4 2001/03/10 10:59:21 mdw Exp $
b7580524 4 *
5 * Build CRC tables
6 *
7 * (c) 2000 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: crc-mktab.c,v $
0521f473 33 * Revision 1.4 2001/03/10 10:59:21 mdw
34 * Fix generating tables where the chunk size is longer than the
35 * polynomial. Also fix output formatting when there aren't enough entries
36 * to fill a line.
37 *
393cf1d9 38 * Revision 1.3 2001/01/20 12:06:01 mdw
39 * Define flags with macros, to ensure unsignedness.
40 *
000ba0de 41 * Revision 1.2 2000/10/08 11:07:21 mdw
42 * With no arguments, give an error rather than spewing a big table at the
43 * user.
44 *
b7580524 45 * Revision 1.1 2000/07/21 19:01:33 mdw
46 * Generate the CRC table rather than hardcoding it.
47 *
48 */
49
50/*----- Header files ------------------------------------------------------*/
51
52#include <ctype.h>
53#include <errno.h>
54#include <limits.h>
55#include <stdarg.h>
56#include <stdio.h>
57#include <stdlib.h>
58#include <string.h>
59
60#include "mdwopt.h"
61#include "quis.h"
62#include "report.h"
63
64/*----- Static variables --------------------------------------------------*/
65
66static unsigned long poly = 0;
67static const char *guard = 0;
68static unsigned bits = 0;
69static unsigned chunk = 8;
70static const char *file = 0;
71static unsigned flags = 0;
72static const char *sym = 0;
73static const char *type = 0;
74static const char *inc = 0;
75static FILE *fp;
76
393cf1d9 77#define f_bogus 1u
78#define f_ctab 2u
79#define f_reverse 4u
b7580524 80
81#define BSCOL 72
82
83/*----- Main code ---------------------------------------------------------*/
84
85static unsigned long getint(const char *p, unsigned long max,
86 const char *what)
87{
88 char *pp;
89 unsigned long x = strtoul(p, &pp, 0);
90 if (*pp || (max && x > max))
91 die(EXIT_FAILURE, "bad %s `%s'", what, p);
92 return (x);
93}
94
95static void version(FILE *fp)
96{
97 pquis(fp, "$, mLib version " VERSION "\n");
98}
99
100static void usage(FILE *fp)
101{
102 pquis(fp, "Usage: $ [-cr] [-g guard] [-o file] [-b bits] [-p poly]\n");
103}
104
105static void help(FILE *fp)
106{
107 version(fp);
108 putc('\n', stdout);
109 usage(fp);
110 fputs("\n\
111Emits a table containing precomuted values for CRC algorithms. A number\n\
112of options are provided:\n\
113\n\
114-h, --help Show this help text.\n\
115-v, --version Show the program's version number.\n\
116-u, --usage Show a terse usage message.\n\
117\n\
118-c, --c-source Emit a C source file rather than a header.\n\
119-b, --bits=BITS Emit a table for a BITS bits-wide CRC.\n\
120-B, --bit-chunk=BITS Emit a table to process BITS bits at a time.\n\
121-p, --polynomial=POLY Use the POLY as the dividing polynomial.\n\
122-r, --reverse Create a `reversed' CRC table.\n\
123-g, --guard=GUARD Use GUARD as a multiple-inclusion guard constant.\n\
124-s, --symbol=SYM Name the generated table SYM\n\
125-t, --type=TYPE Give the table entries type TYPE in C source.\n\
126-o, --output=FILE Write the output to FILE.\n\
127", stdout);
128}
129
130unsigned long reflect(unsigned long x, unsigned b)
131{
132 unsigned long y = 0;
133 unsigned long xm, ym;
134 unsigned i;
135 if (!(flags & f_reverse))
136 return (x);
137 xm = 1;
138 ym = 1 << (b - 1);
139 for (i = 0; i < b; i++) {
140 if (x & xm)
141 y |= ym;
142 xm <<= 1;
143 ym >>= 1;
144 }
145 return (y);
146}
147
148int main(int argc, char *argv[])
149{
150 unsigned n, t, nw;
151 unsigned max, i;
152 unsigned long mask;
153
154 ego(argv[0]);
155
156 for (;;) {
157 static struct option opts[] = {
158 { "help", 0, 0, 'h' },
159 { "version", 0, 0, 'v' },
160 { "usage", 0, 0, 'u' },
161
162 { "output", OPTF_ARGREQ, 0, 'o' },
163 { "c-source", 0, 0, 'c' },
164 { "symbol", OPTF_ARGREQ, 0, 's' },
165 { "type", OPTF_ARGREQ, 0, 't' },
166 { "include", OPTF_ARGREQ, 0, 'i' },
167 { "guard", OPTF_ARGREQ, 0, 'g' },
168
169 { "bits", OPTF_ARGREQ, 0, 'b' },
170 { "bit-chunk", OPTF_ARGREQ, 0, 'B' },
171 { "polynomial", OPTF_ARGREQ, 0, 'p' },
172 { "reverse", 0, 0, 'r' },
173
174 { 0, 0, 0, 0 }
175 };
176 int i = mdwopt(argc, argv, "hvu o:cs:t:i:g: b:B:p:r", opts, 0, 0, 0);
177
178 if (i < 0)
179 break;
180 switch (i) {
181 case 'h':
182 help(stdout);
183 exit(0);
184 case 'v':
185 version(stdout);
186 exit(0);
187 case 'u':
188 usage(stdout);
189 exit(0);
190
191 case 'o':
192 file = optarg;
193 break;
194 case 'c':
195 flags |= f_ctab;
196 break;
197 case 's':
198 sym = optarg;
199 break;
200 case 't':
201 type = optarg;
202 break;
203 case 'i':
204 inc = optarg;
205 break;
206 case 'g':
207 guard = optarg;
208 break;
209
210 case 'b':
211 bits = getint(optarg, 32, "CRC width");
212 break;
213 case 'B':
214 chunk = getint(optarg, 32, "chunk size");
215 break;
216 case 'p':
217 poly = getint(optarg, 0xffffffff, "CRC poly");
218 break;
219 case 'r':
220 flags |= f_reverse;
221 break;
222
223 default:
224 flags |= f_bogus;
225 break;
226 }
227 }
228 if ((flags & f_bogus) || optind != argc) {
229 usage(stderr);
230 exit(EXIT_FAILURE);
231 }
232
233 /* --- Sort out the various parameters --- */
234
235 if (!poly) {
236 switch (bits) {
237 case 16:
238 if (flags & f_reverse)
239 poly = 0x8408;
240 else
241 poly = 0x1021;
242 break;
243 case 32:
b7580524 244 poly = 0x04c11db7;
245 flags |= f_reverse;
246 bits = 32;
247 break;
000ba0de 248 case 0:
249 die(EXIT_FAILURE, "no polynomial or bit width set");
250 break;
b7580524 251 default:
252 die(EXIT_FAILURE, "no standard polynomials for %u bits", bits);
253 break;
254 }
255 }
256
257 if (!bits) {
258 unsigned long x = poly;
259 while (x > 1) {
260 x >>= 8;
261 bits += 8;
262 }
263 }
0521f473 264 nw = (bits + 3)/4;
b7580524 265
266 if ((flags & f_ctab) && !type)
267 type = bits > 16 ? "unsigned long" : "unsigned short";
268
269 /* --- Start output --- */
270
271 if (!file)
272 fp = stdout;
273 else {
274 if (!(flags & f_ctab) && !guard) {
275 char *p;
276 const char *q;
277 if ((p = malloc(strlen(file) + 1)) == 0)
278 die(EXIT_FAILURE, "not enough memory");
279 guard = p;
280 for (q = file; *q; p++, q++) {
281 if (isalnum((unsigned char)*q))
0521f473 282 *p = toupper((unsigned char)*q);
b7580524 283 else
284 *p = '_';
285 }
286 *p++ = 0;
287 }
288 if ((fp = fopen(file, "w")) == 0)
289 die(EXIT_FAILURE, "couldn't write `%s': %s", file, strerror(errno));
290 }
291
292 if (!sym)
293 sym = (flags & f_ctab) ? "crctab" : "CRC_TAB";
294
295 /* --- Dump out the first chunk of the file --- */
296
297 fprintf(fp, "\
298/* -*-c-*-\n\
299 *\n\
300 * CRC table (poly = %0*lx%s) [generated]\n\
301 */\n\
302\n",
303 nw, poly, flags & f_reverse ? "; reversed" : "");
304
305 if (flags & f_ctab) {
306 if (inc)
307 fprintf(fp, "#include \"%s\"\n\n", inc);
308 fprintf(fp, "%s %s[] = {\n", type, sym);
309 } else {
310 int n;
311 if (guard)
312 fprintf(fp, "#ifndef %s\n#define %s\n\n", guard, guard);
313 n = fprintf(fp, "#define %s {", sym);
314 while (n < BSCOL) {
315 fputc('\t', fp);
316 n = (n + 8) & ~7;
317 }
318 fputc('\n', fp);
319 }
320
321 /* --- Sort out the line width --- */
322
323 n = 1;
324 while (2 + n * (nw + 4) < BSCOL)
325 n <<= 1;
326 n >>= 1;
0521f473 327 max = 1 << chunk;
328 if (n > max)
329 n = max;
b7580524 330 t = 0;
331 while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
332 t++;
333
334 /* --- Start grinding --- */
335
b7580524 336 mask = 0xffffffff >> (32 - bits);
337 fputc(' ', fp);
338 for (i = 0; i < max; i++) {
0521f473 339 unsigned long x, y, z;
b7580524 340 unsigned j;
0521f473 341 unsigned ni, nn;
342
343 x = reflect(i, chunk);
344 y = 0;
345 nn = chunk;
346 while (nn) {
347 ni = bits;
348 if (ni > nn)
349 ni = nn;
350 z = (x >> (nn - ni)) & (0xffffffff >> (32 - ni));
351 y ^= z << (bits - ni);
352 for (j = 0; j < ni; j++)
353 y = ((y << 1) ^ (y & (1 << (bits - 1)) ? poly : 0)) & mask;
354 nn -= ni;
355 }
356 x = reflect(y, bits);
b7580524 357
358 fprintf(fp, " 0x%0*lx", nw, x);
359 if (i == max - 1) {
360 if (!(flags & f_ctab) && ((2 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
361 fputc('\t', fp);
362 } else
363 fputc(',', fp);
364 if (i + 1 == max || (i + 1)%n == 0) {
365 if (!(flags & f_ctab)) {
366 for (j = 0; j < t; j++)
367 fputc('\t', fp);
368 fputc('\\', fp);
369 }
370 fputc('\n', fp);
371 if (i + 1 != max)
372 fputc(' ', fp);
373 }
374 }
375
376 /* --- Done --- */
377
378 fputs(flags & f_ctab ? "};\n" : "}\n", fp);
379 if (!(flags & f_ctab) && guard)
380 fputs("\n#endif\n", fp);
381
382 return (0);
383}
384
385/*----- That's all, folks -------------------------------------------------*/