Commit | Line | Data |
---|---|---|
ae747c9b | 1 | /* -*-c-*- |
ae747c9b | 2 | * |
3 | * Low-level arithmetic on binary polynomials | |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
ae747c9b | 9 | * |
10 | * This file is part of Catacomb. | |
11 | * | |
12 | * Catacomb is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
45c0fd36 | 16 | * |
ae747c9b | 17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU Library General Public License for more details. | |
45c0fd36 | 21 | * |
ae747c9b | 22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
ae747c9b | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <assert.h> | |
31 | ||
32 | #include "mpx.h" | |
33 | #include "mpscan.h" | |
34 | ||
35 | /*----- Main code ---------------------------------------------------------*/ | |
36 | ||
37 | /* --- @gfx_add@ --- * | |
38 | * | |
39 | * Arguments: @mpw *dv, *dvl@ = destination vector base and limit | |
40 | * @const mpw *av, *avl@ = first addend vector base and limit | |
41 | * @const mpw *bv, *bvl@ = second addend vector base and limit | |
42 | * | |
43 | * Returns: --- | |
44 | * | |
45 | * Use: Adds two %$\gf{2}$% polynomials. This is the same as | |
46 | * subtraction. | |
47 | */ | |
48 | ||
49 | void gfx_add(mpw *dv, mpw *dvl, | |
50 | const mpw *av, const mpw *avl, | |
51 | const mpw *bv, const mpw *bvl) | |
52 | { | |
53 | MPX_SHRINK(av, avl); | |
54 | MPX_SHRINK(bv, bvl); | |
55 | ||
56 | while (av < avl || bv < bvl) { | |
57 | mpw a, b; | |
58 | if (dv >= dvl) | |
59 | return; | |
60 | a = (av < avl) ? *av++ : 0; | |
61 | b = (bv < bvl) ? *bv++ : 0; | |
62 | *dv++ = a ^ b; | |
63 | } | |
64 | if (dv < dvl) | |
65 | MPX_ZERO(dv, dvl); | |
66 | } | |
67 | ||
68 | /* --- @gfx_acc@ --- * | |
69 | * | |
70 | * Arguments: @mpw *dv, *dvl@ = destination vector base and limit | |
71 | * @const mpw *av, *avl@ = addend vector base and limit | |
72 | * | |
73 | * Returns: --- | |
74 | * | |
75 | * Use: Adds the addend into the destination. This is considerably | |
76 | * faster than the three-address add call. | |
77 | */ | |
78 | ||
79 | void gfx_acc(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl) | |
80 | { | |
81 | size_t dlen, alen; | |
82 | ||
83 | MPX_SHRINK(av, avl); | |
84 | dlen = dvl - dv; | |
85 | alen = avl - av; | |
86 | if (dlen < alen) | |
87 | avl = av + dlen; | |
88 | while (av < avl) | |
89 | *dv++ ^= *av++; | |
90 | } | |
91 | ||
92 | /* --- @gfx_accshift@ --- * | |
93 | * | |
94 | * Arguments: @mpw *dv, *dvl@ = destination vector base and limit | |
95 | * @const mpw *av, *avl@ = addend vector base and limit | |
96 | * @size_t n@ = number of bits to shift | |
97 | * | |
98 | * Returns: --- | |
99 | * | |
100 | * Use: Shifts the argument left by %$n$% places and adds it to the | |
101 | * destination. This is a primitive used by multiplication and | |
102 | * division. | |
103 | */ | |
104 | ||
105 | void gfx_accshift(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, size_t n) | |
106 | { | |
107 | size_t c = n / MPW_BITS; | |
108 | mpw x = 0, y; | |
109 | size_t dlen, alen; | |
110 | ||
111 | /* --- Sort out the shift amounts --- */ | |
112 | ||
113 | if (dvl - dv < c) | |
114 | return; | |
115 | dv += c; | |
116 | n %= MPW_BITS; | |
117 | if (!n) { | |
118 | gfx_acc(dv, dvl, av, avl); | |
119 | return; | |
120 | } | |
121 | c = MPW_BITS - n; | |
122 | ||
123 | /* --- Sort out vector lengths --- */ | |
124 | ||
125 | MPX_SHRINK(av, avl); | |
126 | dlen = dvl - dv; | |
127 | alen = avl - av; | |
128 | if (dlen < alen) | |
129 | avl = av + dlen; | |
130 | ||
131 | /* --- Now do the hard work --- */ | |
132 | ||
133 | while (av < avl) { | |
134 | y = *av++; | |
135 | *dv++ ^= MPW((y << n) | (x >> c)); | |
136 | x = y; | |
137 | } | |
138 | if (dv < dvl) | |
139 | *dv++ ^= x >> c; | |
140 | } | |
141 | ||
142 | /* --- @gfx_mul@ --- * | |
143 | * | |
144 | * Arguments: @mpw *dv, *dvl@ = destination vector base and limit | |
145 | * @const mpw *av, *avl@ = first argument vector base and limit | |
146 | * @const mpw *bv, *bvl@ = second argument vector base and limit | |
147 | * | |
148 | * Returns: --- | |
149 | * | |
150 | * Use: Does multiplication of polynomials over %$\gf{2}$%. | |
151 | */ | |
152 | ||
153 | void gfx_mul(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, | |
154 | const mpw *bv, const mpw *bvl) | |
155 | { | |
156 | mpscan sc; | |
157 | const mpw *v; | |
158 | mpw *vv; | |
159 | mpw z; | |
160 | mpd x, y; | |
161 | ||
162 | MPX_SHRINK(av, avl); | |
163 | MPX_SHRINK(bv, bvl); | |
164 | MPSCAN_INITX(&sc, av, avl); | |
165 | MPX_ZERO(dv, dvl); | |
166 | ||
167 | while (bv < bvl && dv < dvl) { | |
168 | x = 0; | |
169 | for (v = av, vv = dv++; v < avl && vv < dvl; v++) { | |
170 | z = *bv; y = *v; | |
171 | while (z) { | |
172 | if (z & 1u) x ^= y; | |
173 | z >>= 1; y <<= 1; | |
174 | } | |
175 | *vv++ ^= MPW(x); | |
176 | x >>= MPW_BITS; | |
177 | } | |
178 | if (vv < dvl) | |
179 | *vv++ = MPW(x); | |
180 | bv++; | |
181 | } | |
182 | } | |
183 | ||
184 | /* --- @gfx_div@ --- * | |
185 | * | |
186 | * Arguments: @mpw *qv, *qvl@ = quotient vector base and limit | |
45c0fd36 MW |
187 | * @mpw *rv, *rvl@ = dividend/remainder vector base and limit |
188 | * @const mpw *dv, *dvl@ = divisor vector base and limit | |
ae747c9b | 189 | * |
45c0fd36 | 190 | * Returns: --- |
ae747c9b | 191 | * |
45c0fd36 | 192 | * Use: Performs division on polynomials over %$\gf{2}$%. |
ae747c9b | 193 | */ |
194 | ||
195 | void gfx_div(mpw *qv, mpw *qvl, mpw *rv, mpw *rvl, | |
196 | const mpw *dv, const mpw *dvl) | |
197 | { | |
198 | size_t dlen, rlen, qlen; | |
199 | size_t dbits; | |
200 | mpw *rvv, *rvd; | |
201 | unsigned rvm, n, qi; | |
202 | mpw q; | |
203 | ||
204 | MPX_SHRINK(rv, rvl); | |
205 | MPX_SHRINK(dv, dvl); | |
206 | assert(((void)"division by zero in gfx_div", dv < dvl)); | |
207 | MPX_BITS(dbits, dv, dvl); | |
208 | dlen = dvl - dv; | |
209 | rlen = rvl - rv; | |
210 | qlen = qvl - qv; | |
211 | ||
212 | MPX_ZERO(qv, qvl); | |
213 | if (dlen > rlen) | |
214 | return; | |
215 | rvd = rvl - dlen; | |
216 | rvv = rvl - 1; | |
217 | rvm = 1 << (MPW_BITS - 1); | |
218 | n = MPW_BITS - (dbits % MPW_BITS); | |
219 | if (n == MPW_BITS) | |
220 | n = 0; | |
221 | q = 0; | |
222 | qi = rvd - rv; | |
223 | ||
224 | for (;;) { | |
225 | q <<= 1; | |
226 | if (*rvv & rvm) { | |
227 | q |= 1; | |
228 | gfx_accshift(rvd, rvl, dv, dvl, n); | |
229 | } | |
230 | rvm >>= 1; | |
231 | if (!rvm) { | |
232 | rvm = 1 << (MPW_BITS - 1); | |
233 | rvv--; | |
234 | } | |
235 | if (n) | |
236 | n--; | |
237 | else { | |
238 | if (qi < qlen) | |
239 | qv[qi] = q; | |
240 | q = 0; | |
241 | qi--; | |
242 | if (rvd == rv) | |
243 | break; | |
244 | n = MPW_BITS - 1; | |
245 | rvd--; | |
246 | } | |
247 | } | |
248 | } | |
249 | ||
250 | /*----- Test rig ----------------------------------------------------------*/ | |
251 | ||
252 | #ifdef TEST_RIG | |
253 | ||
254 | #include <mLib/alloc.h> | |
255 | #include <mLib/dstr.h> | |
256 | #include <mLib/quis.h> | |
257 | #include <mLib/testrig.h> | |
258 | ||
259 | #define ALLOC(v, vl, sz) do { \ | |
260 | size_t _sz = (sz); \ | |
261 | mpw *_vv = xmalloc(MPWS(_sz)); \ | |
262 | mpw *_vvl = _vv + _sz; \ | |
263 | (v) = _vv; \ | |
264 | (vl) = _vvl; \ | |
265 | } while (0) | |
266 | ||
267 | #define LOAD(v, vl, d) do { \ | |
268 | const dstr *_d = (d); \ | |
269 | mpw *_v, *_vl; \ | |
270 | ALLOC(_v, _vl, MPW_RQ(_d->len)); \ | |
271 | mpx_loadb(_v, _vl, _d->buf, _d->len); \ | |
272 | (v) = _v; \ | |
273 | (vl) = _vl; \ | |
274 | } while (0) | |
275 | ||
276 | #define MAX(x, y) ((x) > (y) ? (x) : (y)) | |
45c0fd36 | 277 | |
ae747c9b | 278 | static void dumpmp(const char *msg, const mpw *v, const mpw *vl) |
279 | { | |
280 | fputs(msg, stderr); | |
281 | MPX_SHRINK(v, vl); | |
282 | while (v < vl) | |
283 | fprintf(stderr, " %08lx", (unsigned long)*--vl); | |
284 | fputc('\n', stderr); | |
285 | } | |
286 | ||
287 | static int vadd(dstr *v) | |
288 | { | |
289 | mpw *a, *al; | |
290 | mpw *b, *bl; | |
291 | mpw *c, *cl; | |
292 | mpw *d, *dl; | |
293 | int ok = 1; | |
294 | ||
295 | LOAD(a, al, &v[0]); | |
296 | LOAD(b, bl, &v[1]); | |
297 | LOAD(c, cl, &v[2]); | |
298 | ALLOC(d, dl, MAX(al - a, bl - b) + 1); | |
299 | ||
300 | gfx_add(d, dl, a, al, b, bl); | |
301 | if (!mpx_ueq(d, dl, c, cl)) { | |
302 | fprintf(stderr, "\n*** vadd failed\n"); | |
45c0fd36 MW |
303 | dumpmp(" a", a, al); |
304 | dumpmp(" b", b, bl); | |
ae747c9b | 305 | dumpmp("expected", c, cl); |
306 | dumpmp(" result", d, dl); | |
307 | ok = 0; | |
308 | } | |
309 | ||
12ed8a1f | 310 | xfree(a); xfree(b); xfree(c); xfree(d); |
ae747c9b | 311 | return (ok); |
312 | } | |
313 | ||
314 | static int vmul(dstr *v) | |
315 | { | |
316 | mpw *a, *al; | |
317 | mpw *b, *bl; | |
318 | mpw *c, *cl; | |
319 | mpw *d, *dl; | |
320 | int ok = 1; | |
321 | ||
322 | LOAD(a, al, &v[0]); | |
323 | LOAD(b, bl, &v[1]); | |
324 | LOAD(c, cl, &v[2]); | |
325 | ALLOC(d, dl, (al - a) + (bl - b)); | |
326 | ||
327 | gfx_mul(d, dl, a, al, b, bl); | |
328 | if (!mpx_ueq(d, dl, c, cl)) { | |
329 | fprintf(stderr, "\n*** vmul failed\n"); | |
45c0fd36 MW |
330 | dumpmp(" a", a, al); |
331 | dumpmp(" b", b, bl); | |
ae747c9b | 332 | dumpmp("expected", c, cl); |
333 | dumpmp(" result", d, dl); | |
334 | ok = 0; | |
335 | } | |
336 | ||
12ed8a1f | 337 | xfree(a); xfree(b); xfree(c); xfree(d); |
ae747c9b | 338 | return (ok); |
339 | } | |
340 | ||
341 | static int vdiv(dstr *v) | |
342 | { | |
343 | mpw *a, *al; | |
344 | mpw *b, *bl; | |
345 | mpw *q, *ql; | |
346 | mpw *r, *rl; | |
347 | mpw *qq, *qql; | |
348 | int ok = 1; | |
349 | ||
350 | ALLOC(a, al, MPW_RQ(v[0].len) + 2); mpx_loadb(a, al, v[0].buf, v[0].len); | |
351 | LOAD(b, bl, &v[1]); | |
352 | LOAD(q, ql, &v[2]); | |
353 | LOAD(r, rl, &v[3]); | |
354 | ALLOC(qq, qql, al - a); | |
355 | ||
356 | gfx_div(qq, qql, a, al, b, bl); | |
357 | if (!mpx_ueq(qq, qql, q, ql) || | |
358 | !mpx_ueq(a, al, r, rl)) { | |
359 | fprintf(stderr, "\n*** vdiv failed\n"); | |
360 | dumpmp(" divisor", b, bl); | |
361 | dumpmp("expect r", r, rl); | |
362 | dumpmp("result r", a, al); | |
363 | dumpmp("expect q", q, ql); | |
364 | dumpmp("result q", qq, qql); | |
365 | ok = 0; | |
366 | } | |
367 | ||
12ed8a1f | 368 | xfree(a); xfree(b); xfree(r); xfree(q); xfree(qq); |
ae747c9b | 369 | return (ok); |
370 | } | |
371 | ||
372 | static test_chunk defs[] = { | |
373 | { "add", vadd, { &type_hex, &type_hex, &type_hex, 0 } }, | |
374 | { "mul", vmul, { &type_hex, &type_hex, &type_hex, 0 } }, | |
375 | { "div", vdiv, { &type_hex, &type_hex, &type_hex, &type_hex, 0 } }, | |
376 | { 0, 0, { 0 } } | |
377 | }; | |
378 | ||
379 | int main(int argc, char *argv[]) | |
380 | { | |
0f00dc4c | 381 | test_run(argc, argv, defs, SRCDIR"/t/gfx"); |
ae747c9b | 382 | return (0); |
383 | } | |
384 | ||
385 | #endif | |
386 | ||
387 | /*----- That's all, folks -------------------------------------------------*/ |