3 * $Id: mp-arith.c,v 1.5 1999/12/22 15:54:41 mdw Exp $
5 * Basic arithmetic on multiprecision integers
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb 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 * Catacomb 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 Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
32 * $Log: mp-arith.c,v $
33 * Revision 1.5 1999/12/22 15:54:41 mdw
34 * Adjust Karatsuba parameters. Calculate destination size better.
36 * Revision 1.4 1999/12/13 15:35:16 mdw
37 * Slightly different rules on memory allocation.
39 * Revision 1.3 1999/12/11 10:57:43 mdw
40 * Karatsuba squaring algorithm.
42 * Revision 1.2 1999/12/10 23:18:39 mdw
43 * Change interface for suggested destinations.
45 * Revision 1.1 1999/11/17 18:02:16 mdw
46 * New multiprecision integer arithmetic suite.
50 /*----- Header files ------------------------------------------------------*/
54 /*----- Macros ------------------------------------------------------------*/
56 #define MAX(x, y) ((x) >= (y) ? (x) : (y))
58 /*----- Main code ---------------------------------------------------------*/
62 * Arguments: @mp *a@ = source
64 * Returns: Result, @a@ converted to two's complement notation.
67 mp *mp_2c(mp *d, mp *a)
72 MP_MODIFY(d, MP_LEN(a));
73 mpx_2c(d->v, d->vl, a->v, a->vl);
74 d->f = a->f & MP_BURN;
81 * Arguments: @mp *d@ = destination
84 * Returns: Result, @a@ converted to the native signed-magnitude
88 mp *mp_sm(mp *d, mp *a)
90 if (!MP_LEN(a) || a->vl[-1] < MPW_MAX / 2)
93 MP_MODIFY(d, MP_LEN(a));
94 mpx_2c(d->v, d->vl, a->v, a->vl);
95 d->f = (a->f & (MP_BURN | MP_NEG)) ^ MP_NEG;
100 /* --- @mp_lsl@ --- *
102 * Arguments: @mp *d@ = destination
104 * @size_t n@ = number of bits to move
106 * Returns: Result, @a@ shifted left by @n@.
109 mp *mp_lsl(mp *d, mp *a, size_t n)
111 MP_MODIFY(d, MP_LEN(a) + (n + MPW_BITS - 1) / MPW_BITS);
112 mpx_lsl(d->v, d->vl, a->v, a->vl, n);
113 d->f = a->f & (MP_NEG | MP_BURN);
118 /* --- @mp_lsr@ --- *
120 * Arguments: @mp *d@ = destination
122 * @size_t n@ = number of bits to move
124 * Returns: Result, @a@ shifted left by @n@.
127 mp *mp_lsr(mp *d, mp *a, size_t n)
129 MP_MODIFY(d, MP_LEN(a));
130 mpx_lsr(d->v, d->vl, a->v, a->vl, n);
131 d->f = a->f & (MP_NEG | MP_BURN);
136 /* --- @mp_cmp@ --- *
138 * Arguments: @const mp *a, *b@ = two numbers
140 * Returns: Less than, equal to or greater than zero, according to
141 * whether @a@ is less than, equal to or greater than @b@.
144 int mp_cmp(const mp *a, const mp *b)
146 if (!((a->f ^ b->f) & MP_NEG))
147 return (mpx_ucmp(a->v, a->vl, b->v, b->vl));
148 else if (a->f & MP_NEG)
154 /* --- @mp_add@ --- *
156 * Arguments: @mp *d@ = destination
157 * @mp *a, *b@ = sources
159 * Returns: Result, @a@ added to @b@.
162 mp *mp_add(mp *d, mp *a, mp *b)
164 MP_MODIFY(d, MAX(MP_LEN(a), MP_LEN(b)) + 1);
165 if (!((a->f ^ b->f) & MP_NEG))
166 mpx_uadd(d->v, d->vl, a->v, a->vl, b->v, b->vl);
168 if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {
169 mp *t = a; a = b; b = t;
171 mpx_usub(d->v, d->vl, a->v, a->vl, b->v, b->vl);
173 d->f = ((a->f | b->f) & MP_BURN) | (a->f & MP_NEG);
178 /* --- @mp_sub@ --- *
180 * Arguments: @mp *d@ = destination
181 * @mp *a, *b@ = sources
183 * Returns: Result, @b@ subtracted from @a@.
186 mp *mp_sub(mp *d, mp *a, mp *b)
189 MP_MODIFY(d, MAX(MP_LEN(a), MP_LEN(b)) + 1);
190 if ((a->f ^ b->f) & MP_NEG)
191 mpx_uadd(d->v, d->vl, a->v, a->vl, b->v, b->vl);
193 if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {
194 mp *t = a; a = b; b = t;
197 mpx_usub(d->v, d->vl, a->v, a->vl, b->v, b->vl);
199 d->f = ((a->f | b->f) & MP_BURN) | ((a->f ^ sgn) & MP_NEG);
204 /* --- @mp_mul@ --- *
206 * Arguments: @mp *d@ = destination
207 * @mp *a, *b@ = sources
209 * Returns: Result, @a@ multiplied by @b@.
212 mp *mp_mul(mp *d, mp *a, mp *b)
217 if (MP_LEN(a) <= KARATSUBA_CUTOFF || MP_LEN(b) <= KARATSUBA_CUTOFF) {
218 MP_MODIFY(d, MP_LEN(a) + MP_LEN(b));
219 mpx_umul(d->v, d->vl, a->v, a->vl, b->v, b->vl);
221 size_t m = 2 * MAX(MP_LEN(a), MP_LEN(b)) + 2;
226 mpx_kmul(d->v, d->vl, a->v, a->vl, b->v, b->vl, s, s + m);
230 d->f = ((a->f | b->f) & MP_BURN) | ((a->f ^ b->f) & MP_NEG);
237 /* --- @mp_sqr@ --- *
239 * Arguments: @mp *d@ = destination
242 * Returns: Result, @a@ squared.
245 mp *mp_sqr(mp *d, mp *a)
247 size_t m = MP_LEN(a);
250 MP_MODIFY(d, 2 * m + 2);
251 if (m > KARATSUBA_CUTOFF) {
253 m = 2 * (m + 1) + KARATSUBA_SLOP;
255 mpx_ksqr(d->v, d->vl, a->v, a->vl, s, s + m);
258 mpx_usqr(d->v, d->vl, a->v, a->vl);
259 d->f = a->f & MP_BURN;
265 /* --- @mp_div@ --- *
267 * Arguments: @mp **qq, **rr@ = destination, quotient and remainder
268 * @mp *a, *b@ = sources
270 * Use: Calculates the quotient and remainder when @a@ is divided by
271 * @b@. The destinations @*qq@ and @*rr@ must be distinct.
272 * Either of @qq@ or @rr@ may be null to indicate that the
273 * result is irrelevant. (Discarding both results is silly.)
274 * There is a performance advantage if @a == *rr@.
276 * The behaviour when @a@ and @b@ have the same sign is
277 * straightforward. When the signs differ, this implementation
278 * chooses @r@ to have the same sign as @b@, rather than the
279 * more normal choice that the remainder has the same sign as
280 * the dividend. This makes modular arithmetic a little more
284 void mp_div(mp **qq, mp **rr, mp *a, mp *b)
286 mp *r = rr ? *rr : MP_NEW;
287 mp *q = qq ? *qq : MP_NEW;
290 /* --- Set up some temporary workspace --- */
293 size_t rq = MP_LEN(b) + 1;
298 /* --- Set the remainder up right --- *
300 * Just in case the divisor is larger, be able to cope with this. It's not
301 * important in @mpx_udiv@, but it is here because of the sign correction.
305 size_t rq = MP_LEN(a) + 2;
313 MP_ENSURE(r, MP_LEN(r) + 2);
316 MP_MODIFY(r, MP_LEN(a) + 2);
317 memcpy(r->v, a->v, MPWS(MP_LEN(a)));
318 memset(r->v + MP_LEN(a), 0, MPWS(2));
322 /* --- Fix up the quotient too --- */
324 MP_MODIFY(q, MP_LEN(a));
326 /* --- Perform the calculation --- */
328 mpx_udiv(q->v, q->vl, r->v, r->vl, b->v, b->vl, sv, svl);
330 /* --- Sort out the sign of the results --- *
332 * If the signs of the arguments differ, and the remainder is nonzero, I
333 * must add one to the absolute value of the quotient and subtract the
334 * remainder from @b@.
337 q->f = ((a->f | b->f) & MP_BURN) | ((a->f ^ b->f) & MP_NEG);
340 for (v = r->v; v < r->vl; v++) {
342 MPX_UADDN(q->v, q->vl, 1);
343 mpx_usub(r->v, r->vl, b->v, b->vl, r->v, r->vl);
349 r->f = ((a->f | b->f) & MP_BURN) | (b->f & MP_NEG);
351 /* --- Store the return values --- */
372 /*----- Test rig ----------------------------------------------------------*/
376 static int verify(const char *op, mp *expect, mp *result, mp *a, mp *b)
378 if (MP_CMP(expect, !=, result)) {
379 fprintf(stderr, "\n*** %s failed", op);
380 fputs("\n*** a = ", stderr); mp_writefile(a, stderr, 10);
381 fputs("\n*** b = ", stderr); mp_writefile(b, stderr, 10);
382 fputs("\n*** result = ", stderr); mp_writefile(result, stderr, 10);
383 fputs("\n*** expect = ", stderr); mp_writefile(expect, stderr, 10);
390 #define RIG(name, op) \
391 static int t##name(dstr *v) \
393 mp *a = *(mp **)v[0].buf; \
394 mpw n = *(int *)v[1].buf; \
396 mp *r = *(mp **)v[2].buf; \
397 mp *c = op(MP_NEW, a, n); \
399 mp_build(&b, &n, &n + 1); \
400 ok = verify(#name, r, c, a, &b); \
401 mp_drop(a); mp_drop(c); mp_drop(r); \
402 assert(mparena_count(MPARENA_GLOBAL) == 0); \
411 #define RIG(name, op) \
412 static int t##name(dstr *v) \
414 mp *a = *(mp **)v[0].buf; \
415 mp *b = *(mp **)v[1].buf; \
416 mp *r = *(mp **)v[2].buf; \
417 mp *c = op(MP_NEW, a, b); \
418 int ok = verify(#name, r, c, a, b); \
419 mp_drop(a); mp_drop(b); mp_drop(c); mp_drop(r); \
420 assert(mparena_count(MPARENA_GLOBAL) == 0); \
430 static int tdiv(dstr *v)
432 mp *a = *(mp **)v[0].buf;
433 mp *b = *(mp **)v[1].buf;
434 mp *q = *(mp **)v[2].buf;
435 mp *r = *(mp **)v[3].buf;
436 mp *c = MP_NEW, *d = MP_NEW;
438 mp_div(&c, &d, a, b);
439 ok &= verify("div(quotient)", q, c, a, b);
440 ok &= verify("div(remainder)", r, d, a, b);
441 mp_drop(a); mp_drop(b); mp_drop(c); mp_drop(d); mp_drop(r); mp_drop(q);
442 assert(mparena_count(MPARENA_GLOBAL) == 0);
446 static test_chunk tests[] = {
447 { "lsl", tlsl, { &type_mp, &type_mp, &type_mp, 0 } },
448 { "lsr", tlsr, { &type_mp, &type_mp, &type_mp, 0 } },
449 { "add", tadd, { &type_mp, &type_mp, &type_mp, 0 } },
450 { "sub", tsub, { &type_mp, &type_mp, &type_mp, 0 } },
451 { "mul", tmul, { &type_mp, &type_mp, &type_mp, 0 } },
452 { "div", tdiv, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
456 int main(int argc, char *argv[])
459 test_run(argc, argv, tests, SRCDIR "/tests/mp");
465 /*----- That's all, folks -------------------------------------------------*/