3 * $Id: crc-mktab.c,v 1.4 2001/03/10 10:59:21 mdw Exp $
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
32 * $Log: crc-mktab.c,v $
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
38 * Revision 1.3 2001/01/20 12:06:01 mdw
39 * Define flags with macros, to ensure unsignedness.
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
45 * Revision 1.1 2000/07/21 19:01:33 mdw
46 * Generate the CRC table rather than hardcoding it.
50 /*----- Header files ------------------------------------------------------*/
64 /*----- Static variables --------------------------------------------------*/
66 static unsigned long poly = 0;
67 static const char *guard = 0;
68 static unsigned bits = 0;
69 static unsigned chunk = 8;
70 static const char *file = 0;
71 static unsigned flags = 0;
72 static const char *sym = 0;
73 static const char *type = 0;
74 static const char *inc = 0;
83 /*----- Main code ---------------------------------------------------------*/
85 static unsigned long getint(const char *p, unsigned long max,
89 unsigned long x = strtoul(p, &pp, 0);
90 if (*pp || (max && x > max))
91 die(EXIT_FAILURE, "bad %s `%s'", what, p);
95 static void version(FILE *fp)
97 pquis(fp, "$, mLib version " VERSION "\n");
100 static void usage(FILE *fp)
102 pquis(fp, "Usage: $ [-cr] [-g guard] [-o file] [-b bits] [-p poly]\n");
105 static void help(FILE *fp)
111 Emits a table containing precomuted values for CRC algorithms. A number\n\
112 of options are provided:\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\
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\
130 unsigned long reflect(unsigned long x, unsigned b)
133 unsigned long xm, ym;
135 if (!(flags & f_reverse))
139 for (i = 0; i < b; i++) {
148 int main(int argc, char *argv[])
157 static struct option opts[] = {
158 { "help", 0, 0, 'h' },
159 { "version", 0, 0, 'v' },
160 { "usage", 0, 0, 'u' },
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' },
169 { "bits", OPTF_ARGREQ, 0, 'b' },
170 { "bit-chunk", OPTF_ARGREQ, 0, 'B' },
171 { "polynomial", OPTF_ARGREQ, 0, 'p' },
172 { "reverse", 0, 0, 'r' },
176 int i = mdwopt(argc, argv, "hvu o:cs:t:i:g: b:B:p:r", opts, 0, 0, 0);
211 bits = getint(optarg, 32, "CRC width");
214 chunk = getint(optarg, 32, "chunk size");
217 poly = getint(optarg, 0xffffffff, "CRC poly");
228 if ((flags & f_bogus) || optind != argc) {
233 /* --- Sort out the various parameters --- */
238 if (flags & f_reverse)
249 die(EXIT_FAILURE, "no polynomial or bit width set");
252 die(EXIT_FAILURE, "no standard polynomials for %u bits", bits);
258 unsigned long x = poly;
266 if ((flags & f_ctab) && !type)
267 type = bits > 16 ? "unsigned long" : "unsigned short";
269 /* --- Start output --- */
274 if (!(flags & f_ctab) && !guard) {
277 if ((p = malloc(strlen(file) + 1)) == 0)
278 die(EXIT_FAILURE, "not enough memory");
280 for (q = file; *q; p++, q++) {
281 if (isalnum((unsigned char)*q))
282 *p = toupper((unsigned char)*q);
288 if ((fp = fopen(file, "w")) == 0)
289 die(EXIT_FAILURE, "couldn't write `%s': %s", file, strerror(errno));
293 sym = (flags & f_ctab) ? "crctab" : "CRC_TAB";
295 /* --- Dump out the first chunk of the file --- */
300 * CRC table (poly = %0*lx%s) [generated]\n\
303 nw, poly, flags & f_reverse ? "; reversed" : "");
305 if (flags & f_ctab) {
307 fprintf(fp, "#include \"%s\"\n\n", inc);
308 fprintf(fp, "%s %s[] = {\n", type, sym);
312 fprintf(fp, "#ifndef %s\n#define %s\n\n", guard, guard);
313 n = fprintf(fp, "#define %s {", sym);
321 /* --- Sort out the line width --- */
324 while (2 + n * (nw + 4) < BSCOL)
331 while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
334 /* --- Start grinding --- */
336 mask = 0xffffffff >> (32 - bits);
338 for (i = 0; i < max; i++) {
339 unsigned long x, y, z;
343 x = reflect(i, chunk);
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;
356 x = reflect(y, bits);
358 fprintf(fp, " 0x%0*lx", nw, x);
360 if (!(flags & f_ctab) && ((2 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
364 if (i + 1 == max || (i + 1)%n == 0) {
365 if (!(flags & f_ctab)) {
366 for (j = 0; j < t; j++)
378 fputs(flags & f_ctab ? "};\n" : "}\n", fp);
379 if (!(flags & f_ctab) && guard)
380 fputs("\n#endif\n", fp);
385 /*----- That's all, folks -------------------------------------------------*/