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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: crc-mktab.c,v 1.2 2000/10/08 11:07:21 mdw Exp $ |
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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 $ |
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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 |
35 | * user. |
36 | * |
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37 | * Revision 1.1 2000/07/21 19:01:33 mdw |
38 | * Generate the CRC table rather than hardcoding it. |
39 | * |
40 | */ |
41 | |
42 | /*----- Header files ------------------------------------------------------*/ |
43 | |
44 | #include <ctype.h> |
45 | #include <errno.h> |
46 | #include <limits.h> |
47 | #include <stdarg.h> |
48 | #include <stdio.h> |
49 | #include <stdlib.h> |
50 | #include <string.h> |
51 | |
52 | #include "mdwopt.h" |
53 | #include "quis.h" |
54 | #include "report.h" |
55 | |
56 | /*----- Static variables --------------------------------------------------*/ |
57 | |
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; |
67 | static FILE *fp; |
68 | |
69 | enum { |
70 | f_bogus = 1, |
71 | f_ctab = 2, |
72 | f_reverse = 4 |
73 | }; |
74 | |
75 | #define BSCOL 72 |
76 | |
77 | /*----- Main code ---------------------------------------------------------*/ |
78 | |
79 | static unsigned long getint(const char *p, unsigned long max, |
80 | const char *what) |
81 | { |
82 | char *pp; |
83 | unsigned long x = strtoul(p, &pp, 0); |
84 | if (*pp || (max && x > max)) |
85 | die(EXIT_FAILURE, "bad %s `%s'", what, p); |
86 | return (x); |
87 | } |
88 | |
89 | static void version(FILE *fp) |
90 | { |
91 | pquis(fp, "$, mLib version " VERSION "\n"); |
92 | } |
93 | |
94 | static void usage(FILE *fp) |
95 | { |
96 | pquis(fp, "Usage: $ [-cr] [-g guard] [-o file] [-b bits] [-p poly]\n"); |
97 | } |
98 | |
99 | static void help(FILE *fp) |
100 | { |
101 | version(fp); |
102 | putc('\n', stdout); |
103 | usage(fp); |
104 | fputs("\n\ |
105 | Emits a table containing precomuted values for CRC algorithms. A number\n\ |
106 | of options are provided:\n\ |
107 | \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\ |
111 | \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\ |
121 | ", stdout); |
122 | } |
123 | |
124 | unsigned long reflect(unsigned long x, unsigned b) |
125 | { |
126 | unsigned long y = 0; |
127 | unsigned long xm, ym; |
128 | unsigned i; |
129 | if (!(flags & f_reverse)) |
130 | return (x); |
131 | xm = 1; |
132 | ym = 1 << (b - 1); |
133 | for (i = 0; i < b; i++) { |
134 | if (x & xm) |
135 | y |= ym; |
136 | xm <<= 1; |
137 | ym >>= 1; |
138 | } |
139 | return (y); |
140 | } |
141 | |
142 | int main(int argc, char *argv[]) |
143 | { |
144 | unsigned n, t, nw; |
145 | unsigned max, i; |
146 | unsigned long mask; |
147 | |
148 | ego(argv[0]); |
149 | |
150 | for (;;) { |
151 | static struct option opts[] = { |
152 | { "help", 0, 0, 'h' }, |
153 | { "version", 0, 0, 'v' }, |
154 | { "usage", 0, 0, 'u' }, |
155 | |
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' }, |
162 | |
163 | { "bits", OPTF_ARGREQ, 0, 'b' }, |
164 | { "bit-chunk", OPTF_ARGREQ, 0, 'B' }, |
165 | { "polynomial", OPTF_ARGREQ, 0, 'p' }, |
166 | { "reverse", 0, 0, 'r' }, |
167 | |
168 | { 0, 0, 0, 0 } |
169 | }; |
170 | int i = mdwopt(argc, argv, "hvu o:cs:t:i:g: b:B:p:r", opts, 0, 0, 0); |
171 | |
172 | if (i < 0) |
173 | break; |
174 | switch (i) { |
175 | case 'h': |
176 | help(stdout); |
177 | exit(0); |
178 | case 'v': |
179 | version(stdout); |
180 | exit(0); |
181 | case 'u': |
182 | usage(stdout); |
183 | exit(0); |
184 | |
185 | case 'o': |
186 | file = optarg; |
187 | break; |
188 | case 'c': |
189 | flags |= f_ctab; |
190 | break; |
191 | case 's': |
192 | sym = optarg; |
193 | break; |
194 | case 't': |
195 | type = optarg; |
196 | break; |
197 | case 'i': |
198 | inc = optarg; |
199 | break; |
200 | case 'g': |
201 | guard = optarg; |
202 | break; |
203 | |
204 | case 'b': |
205 | bits = getint(optarg, 32, "CRC width"); |
206 | break; |
207 | case 'B': |
208 | chunk = getint(optarg, 32, "chunk size"); |
209 | break; |
210 | case 'p': |
211 | poly = getint(optarg, 0xffffffff, "CRC poly"); |
212 | break; |
213 | case 'r': |
214 | flags |= f_reverse; |
215 | break; |
216 | |
217 | default: |
218 | flags |= f_bogus; |
219 | break; |
220 | } |
221 | } |
222 | if ((flags & f_bogus) || optind != argc) { |
223 | usage(stderr); |
224 | exit(EXIT_FAILURE); |
225 | } |
226 | |
227 | /* --- Sort out the various parameters --- */ |
228 | |
229 | if (!poly) { |
230 | switch (bits) { |
231 | case 16: |
232 | if (flags & f_reverse) |
233 | poly = 0x8408; |
234 | else |
235 | poly = 0x1021; |
236 | break; |
237 | case 32: |
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238 | poly = 0x04c11db7; |
239 | flags |= f_reverse; |
240 | bits = 32; |
241 | break; |
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242 | case 0: |
243 | die(EXIT_FAILURE, "no polynomial or bit width set"); |
244 | break; |
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245 | default: |
246 | die(EXIT_FAILURE, "no standard polynomials for %u bits", bits); |
247 | break; |
248 | } |
249 | } |
250 | |
251 | if (!bits) { |
252 | unsigned long x = poly; |
253 | while (x > 1) { |
254 | x >>= 8; |
255 | bits += 8; |
256 | } |
257 | } |
258 | nw = bits/4; |
259 | |
260 | if ((flags & f_ctab) && !type) |
261 | type = bits > 16 ? "unsigned long" : "unsigned short"; |
262 | |
263 | /* --- Start output --- */ |
264 | |
265 | if (!file) |
266 | fp = stdout; |
267 | else { |
268 | if (!(flags & f_ctab) && !guard) { |
269 | char *p; |
270 | const char *q; |
271 | if ((p = malloc(strlen(file) + 1)) == 0) |
272 | die(EXIT_FAILURE, "not enough memory"); |
273 | guard = p; |
274 | for (q = file; *q; p++, q++) { |
275 | if (isalnum((unsigned char)*q)) |
276 | *p = *q; |
277 | else |
278 | *p = '_'; |
279 | } |
280 | *p++ = 0; |
281 | } |
282 | if ((fp = fopen(file, "w")) == 0) |
283 | die(EXIT_FAILURE, "couldn't write `%s': %s", file, strerror(errno)); |
284 | } |
285 | |
286 | if (!sym) |
287 | sym = (flags & f_ctab) ? "crctab" : "CRC_TAB"; |
288 | |
289 | /* --- Dump out the first chunk of the file --- */ |
290 | |
291 | fprintf(fp, "\ |
292 | /* -*-c-*-\n\ |
293 | *\n\ |
294 | * CRC table (poly = %0*lx%s) [generated]\n\ |
295 | */\n\ |
296 | \n", |
297 | nw, poly, flags & f_reverse ? "; reversed" : ""); |
298 | |
299 | if (flags & f_ctab) { |
300 | if (inc) |
301 | fprintf(fp, "#include \"%s\"\n\n", inc); |
302 | fprintf(fp, "%s %s[] = {\n", type, sym); |
303 | } else { |
304 | int n; |
305 | if (guard) |
306 | fprintf(fp, "#ifndef %s\n#define %s\n\n", guard, guard); |
307 | n = fprintf(fp, "#define %s {", sym); |
308 | while (n < BSCOL) { |
309 | fputc('\t', fp); |
310 | n = (n + 8) & ~7; |
311 | } |
312 | fputc('\n', fp); |
313 | } |
314 | |
315 | /* --- Sort out the line width --- */ |
316 | |
317 | n = 1; |
318 | while (2 + n * (nw + 4) < BSCOL) |
319 | n <<= 1; |
320 | n >>= 1; |
321 | t = 0; |
322 | while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL) |
323 | t++; |
324 | |
325 | /* --- Start grinding --- */ |
326 | |
327 | max = 1 << chunk; |
328 | mask = 0xffffffff >> (32 - bits); |
329 | fputc(' ', fp); |
330 | for (i = 0; i < max; i++) { |
331 | unsigned long x; |
332 | unsigned j; |
333 | |
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); |
338 | |
339 | fprintf(fp, " 0x%0*lx", nw, x); |
340 | if (i == max - 1) { |
341 | if (!(flags & f_ctab) && ((2 + n * (nw + 4)) & ~7) + 8 * t < BSCOL) |
342 | fputc('\t', fp); |
343 | } else |
344 | fputc(',', fp); |
345 | if (i + 1 == max || (i + 1)%n == 0) { |
346 | if (!(flags & f_ctab)) { |
347 | for (j = 0; j < t; j++) |
348 | fputc('\t', fp); |
349 | fputc('\\', fp); |
350 | } |
351 | fputc('\n', fp); |
352 | if (i + 1 != max) |
353 | fputc(' ', fp); |
354 | } |
355 | } |
356 | |
357 | /* --- Done --- */ |
358 | |
359 | fputs(flags & f_ctab ? "};\n" : "}\n", fp); |
360 | if (!(flags & f_ctab) && guard) |
361 | fputs("\n#endif\n", fp); |
362 | |
363 | return (0); |
364 | } |
365 | |
366 | /*----- That's all, folks -------------------------------------------------*/ |