3 * $Id: crc-mktab.c,v 1.2 2000/10/08 11:07:21 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 1.2 2000/10/08 11:07:21 mdw
34 * With no arguments, give an error rather than spewing a big table at the
37 * Revision 1.1 2000/07/21 19:01:33 mdw
38 * Generate the CRC table rather than hardcoding it.
42 /*----- Header files ------------------------------------------------------*/
56 /*----- Static variables --------------------------------------------------*/
58 static unsigned long poly = 0;
59 static const char *guard = 0;
60 static unsigned bits = 0;
61 static unsigned chunk = 8;
62 static const char *file = 0;
63 static unsigned flags = 0;
64 static const char *sym = 0;
65 static const char *type = 0;
66 static const char *inc = 0;
77 /*----- Main code ---------------------------------------------------------*/
79 static unsigned long getint(const char *p, unsigned long max,
83 unsigned long x = strtoul(p, &pp, 0);
84 if (*pp || (max && x > max))
85 die(EXIT_FAILURE, "bad %s `%s'", what, p);
89 static void version(FILE *fp)
91 pquis(fp, "$, mLib version " VERSION "\n");
94 static void usage(FILE *fp)
96 pquis(fp, "Usage: $ [-cr] [-g guard] [-o file] [-b bits] [-p poly]\n");
99 static void help(FILE *fp)
105 Emits a table containing precomuted values for CRC algorithms. A number\n\
106 of options are provided:\n\
108 -h, --help Show this help text.\n\
109 -v, --version Show the program's version number.\n\
110 -u, --usage Show a terse usage message.\n\
112 -c, --c-source Emit a C source file rather than a header.\n\
113 -b, --bits=BITS Emit a table for a BITS bits-wide CRC.\n\
114 -B, --bit-chunk=BITS Emit a table to process BITS bits at a time.\n\
115 -p, --polynomial=POLY Use the POLY as the dividing polynomial.\n\
116 -r, --reverse Create a `reversed' CRC table.\n\
117 -g, --guard=GUARD Use GUARD as a multiple-inclusion guard constant.\n\
118 -s, --symbol=SYM Name the generated table SYM\n\
119 -t, --type=TYPE Give the table entries type TYPE in C source.\n\
120 -o, --output=FILE Write the output to FILE.\n\
124 unsigned long reflect(unsigned long x, unsigned b)
127 unsigned long xm, ym;
129 if (!(flags & f_reverse))
133 for (i = 0; i < b; i++) {
142 int main(int argc, char *argv[])
151 static struct option opts[] = {
152 { "help", 0, 0, 'h' },
153 { "version", 0, 0, 'v' },
154 { "usage", 0, 0, 'u' },
156 { "output", OPTF_ARGREQ, 0, 'o' },
157 { "c-source", 0, 0, 'c' },
158 { "symbol", OPTF_ARGREQ, 0, 's' },
159 { "type", OPTF_ARGREQ, 0, 't' },
160 { "include", OPTF_ARGREQ, 0, 'i' },
161 { "guard", OPTF_ARGREQ, 0, 'g' },
163 { "bits", OPTF_ARGREQ, 0, 'b' },
164 { "bit-chunk", OPTF_ARGREQ, 0, 'B' },
165 { "polynomial", OPTF_ARGREQ, 0, 'p' },
166 { "reverse", 0, 0, 'r' },
170 int i = mdwopt(argc, argv, "hvu o:cs:t:i:g: b:B:p:r", opts, 0, 0, 0);
205 bits = getint(optarg, 32, "CRC width");
208 chunk = getint(optarg, 32, "chunk size");
211 poly = getint(optarg, 0xffffffff, "CRC poly");
222 if ((flags & f_bogus) || optind != argc) {
227 /* --- Sort out the various parameters --- */
232 if (flags & f_reverse)
243 die(EXIT_FAILURE, "no polynomial or bit width set");
246 die(EXIT_FAILURE, "no standard polynomials for %u bits", bits);
252 unsigned long x = poly;
260 if ((flags & f_ctab) && !type)
261 type = bits > 16 ? "unsigned long" : "unsigned short";
263 /* --- Start output --- */
268 if (!(flags & f_ctab) && !guard) {
271 if ((p = malloc(strlen(file) + 1)) == 0)
272 die(EXIT_FAILURE, "not enough memory");
274 for (q = file; *q; p++, q++) {
275 if (isalnum((unsigned char)*q))
282 if ((fp = fopen(file, "w")) == 0)
283 die(EXIT_FAILURE, "couldn't write `%s': %s", file, strerror(errno));
287 sym = (flags & f_ctab) ? "crctab" : "CRC_TAB";
289 /* --- Dump out the first chunk of the file --- */
294 * CRC table (poly = %0*lx%s) [generated]\n\
297 nw, poly, flags & f_reverse ? "; reversed" : "");
299 if (flags & f_ctab) {
301 fprintf(fp, "#include \"%s\"\n\n", inc);
302 fprintf(fp, "%s %s[] = {\n", type, sym);
306 fprintf(fp, "#ifndef %s\n#define %s\n\n", guard, guard);
307 n = fprintf(fp, "#define %s {", sym);
315 /* --- Sort out the line width --- */
318 while (2 + n * (nw + 4) < BSCOL)
322 while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
325 /* --- Start grinding --- */
328 mask = 0xffffffff >> (32 - bits);
330 for (i = 0; i < max; i++) {
334 x = reflect(i, chunk) << (bits - chunk);
335 for (j = 0; j < chunk; j++)
336 x = ((x << 1) ^ (x & (1 << (bits - 1)) ? poly : 0)) & mask;
337 x = reflect(x, bits);
339 fprintf(fp, " 0x%0*lx", nw, x);
341 if (!(flags & f_ctab) && ((2 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
345 if (i + 1 == max || (i + 1)%n == 0) {
346 if (!(flags & f_ctab)) {
347 for (j = 0; j < t; j++)
359 fputs(flags & f_ctab ? "};\n" : "}\n", fp);
360 if (!(flags & f_ctab) && guard)
361 fputs("\n#endif\n", fp);
366 /*----- That's all, folks -------------------------------------------------*/