3 * $Id: crc-mktab.c,v 1.6 2004/04/08 01:36:11 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 /*----- Header files ------------------------------------------------------*/
44 /*----- Static variables --------------------------------------------------*/
46 static unsigned long poly = 0;
47 static const char *guard = 0;
48 static unsigned bits = 0;
49 static unsigned chunk = 8;
50 static const char *file = 0;
51 static unsigned flags = 0;
52 static const char *sym = 0;
53 static const char *type = 0;
54 static const char *inc = 0;
63 /*----- Main code ---------------------------------------------------------*/
65 static unsigned long getint(const char *p, unsigned long max,
69 unsigned long x = strtoul(p, &pp, 0);
70 if (*pp || (max && x > max))
71 die(EXIT_FAILURE, "bad %s `%s'", what, p);
75 static void version(FILE *fp)
77 pquis(fp, "$, mLib version " VERSION "\n");
80 static void usage(FILE *fp)
82 pquis(fp, "Usage: $ [-cr] [-o FILE] [-g GUARD] [-s SYM] [-i HEADER]\n\
83 [-t TYPE] [-b BITS] [-B BITS] [-p POLY]\n");
86 static void help(FILE *fp)
92 Emits a table containing precomuted values for CRC algorithms. A number\n\
93 of options are provided:\n\
95 -h, --help Show this help text.\n\
96 -v, --version Show the program's version number.\n\
97 -u, --usage Show a terse usage message.\n\
99 -c, --c-source Emit a C source file rather than a header.\n\
100 -b, --bits=BITS Emit a table for a BITS bits-wide CRC.\n\
101 -B, --bit-chunk=BITS Emit a table to process BITS bits at a time.\n\
102 -p, --polynomial=POLY Use the POLY as the dividing polynomial.\n\
103 -r, --reverse Create a `reversed' CRC table.\n\
104 -g, --guard=GUARD Use GUARD as a multiple-inclusion guard constant.\n\
105 -i, --include=HEADER Include HEADER at top of C source file.\n\
106 -s, --symbol=SYM Name the generated table SYM.\n\
107 -t, --type=TYPE Give the table entries type TYPE in C source.\n\
108 -o, --output=FILE Write the output to FILE.\n\
112 unsigned long reflect(unsigned long x, unsigned b)
115 unsigned long xm, ym;
117 if (!(flags & f_reverse))
121 for (i = 0; i < b; i++) {
130 int main(int argc, char *argv[])
139 static struct option opts[] = {
140 { "help", 0, 0, 'h' },
141 { "version", 0, 0, 'v' },
142 { "usage", 0, 0, 'u' },
144 { "output", OPTF_ARGREQ, 0, 'o' },
145 { "c-source", 0, 0, 'c' },
146 { "symbol", OPTF_ARGREQ, 0, 's' },
147 { "type", OPTF_ARGREQ, 0, 't' },
148 { "include", OPTF_ARGREQ, 0, 'i' },
149 { "guard", OPTF_ARGREQ, 0, 'g' },
151 { "bits", OPTF_ARGREQ, 0, 'b' },
152 { "bit-chunk", OPTF_ARGREQ, 0, 'B' },
153 { "polynomial", OPTF_ARGREQ, 0, 'p' },
154 { "reverse", 0, 0, 'r' },
158 int i = mdwopt(argc, argv, "hvu o:cs:t:i:g: b:B:p:r", opts, 0, 0, 0);
193 bits = getint(optarg, 32, "CRC width");
196 chunk = getint(optarg, 32, "chunk size");
199 poly = getint(optarg, 0xffffffff, "CRC poly");
210 if ((flags & f_bogus) || optind != argc) {
215 /* --- Sort out the various parameters --- */
220 if (flags & f_reverse)
231 die(EXIT_FAILURE, "no polynomial or bit width set");
234 die(EXIT_FAILURE, "no standard polynomials for %u bits", bits);
240 unsigned long x = poly;
248 if ((flags & f_ctab) && !type)
249 type = bits > 16 ? "unsigned long" : "unsigned short";
251 /* --- Start output --- */
256 if (!(flags & f_ctab) && !guard) {
259 if ((p = malloc(strlen(file) + 1)) == 0)
260 die(EXIT_FAILURE, "not enough memory");
262 for (q = file; *q; p++, q++) {
263 if (isalnum((unsigned char)*q))
264 *p = toupper((unsigned char)*q);
270 if ((fp = fopen(file, "w")) == 0)
271 die(EXIT_FAILURE, "couldn't write `%s': %s", file, strerror(errno));
275 sym = (flags & f_ctab) ? "crctab" : "CRC_TAB";
277 /* --- Dump out the first chunk of the file --- */
282 * CRC table (poly = %0*lx%s) [generated]\n\
285 nw, poly, flags & f_reverse ? "; reversed" : "");
287 if (flags & f_ctab) {
289 fprintf(fp, "#include \"%s\"\n\n", inc);
290 fprintf(fp, "%s %s[] = {\n", type, sym);
294 fprintf(fp, "#ifndef %s\n#define %s\n\n", guard, guard);
295 n = fprintf(fp, "#define %s {", sym);
303 /* --- Sort out the line width --- */
306 while (2 + n * (nw + 4) < BSCOL)
313 while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
316 /* --- Start grinding --- */
318 mask = 0xffffffff >> (32 - bits);
320 for (i = 0; i < max; i++) {
321 unsigned long x, y, z;
325 x = reflect(i, chunk);
332 z = (x >> (nn - ni)) & (0xffffffff >> (32 - ni));
333 y ^= z << (bits - ni);
334 for (j = 0; j < ni; j++)
335 y = ((y << 1) ^ (y & (1 << (bits - 1)) ? poly : 0)) & mask;
338 x = reflect(y, bits);
340 fprintf(fp, " 0x%0*lx", nw, x);
342 if (!(flags & f_ctab) && ((2 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
346 if (i + 1 == max || (i + 1)%n == 0) {
347 if (!(flags & f_ctab)) {
348 for (j = 0; j < t; j++)
360 fputs(flags & f_ctab ? "};\n" : "}\n", fp);
361 if (!(flags & f_ctab) && guard)
362 fputs("\n#endif\n", fp);
367 /*----- That's all, folks -------------------------------------------------*/