/* -*-c-*-
*
- * $Id: mp-gcd.c,v 1.7 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* Extended GCD calculation
*
* (c) 1999 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
- *
+ *
* Catacomb is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
- *
+ *
* You should have received a copy of the GNU Library General Public
* License along with Catacomb; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
if (xx || yy)
f |= f_ext;
- if (a->f & MP_NEG)
+ if (MP_NEGP(a))
f |= f_aneg;
- if (b->f & MP_NEG)
+ if (MP_NEGP(b))
f |= f_bneg;
/* --- Ensure that @a@ is larger than @b@ --- *
if (gcd) {
if (*gcd) MP_DROP(*gcd);
a = MP_COPY(a);
- if (a->f & MP_NEG) {
+ if (MP_NEGP(a)) {
MP_SPLIT(a);
a->f &= ~MP_NEG;
f |= f_aneg;
return;
}
- /* --- Take a reference to the arguments --- */
+ /* --- Force the signs on the arguments and take copies --- */
a = MP_COPY(a);
b = MP_COPY(b);
- /* --- Make sure @a@ and @b@ are not both even --- */
-
MP_SPLIT(a); a->f &= ~MP_NEG;
MP_SPLIT(b); b->f &= ~MP_NEG;
u = MP_COPY(a);
v = MP_COPY(b);
- while (MP_LEN(v)) {
+ /* --- Main extended Euclidean algorithm --- */
+
+ while (!MP_ZEROP(v)) {
mp *t;
mp_div(&q, &u, u, v);
if (f & f_ext) {
*/
if (yy) {
- if (y->f & MP_NEG) {
+ if (MP_NEGP(y)) {
do {
y = mp_add(y, y, a);
x = mp_sub(x, x, b);
- } while (y->f & MP_NEG);
+ } while (MP_NEGP(y));
} else {
while (MP_CMP(y, >=, a)) {
y = mp_sub(y, y, a);
}
}
} else {
- if (x->f & MP_NEG) {
+ if (MP_NEGP(x)) {
do
x = mp_add(x, x, b);
- while (x->f & MP_NEG);
+ while (MP_NEGP(x));
} else {
while (MP_CMP(x, >=, b))
x = mp_sub(x, x, b);
#ifdef TEST_RIG
+static int modinv(dstr *v)
+{
+ int ok = 1;
+ mp *x = *(mp **)v[0].buf;
+ mp *m = *(mp **)v[1].buf;
+ mp *r = *(mp **)v[2].buf;
+
+ mp *y = mp_modinv(MP_NEW, x, m);
+ if (!MP_EQ(y, r)) {
+ fputs("\n*** mp_modinv failed", stderr);
+ fputs("\nx = ", stderr); mp_writefile(x, stderr, 10);
+ fputs("\nm = ", stderr); mp_writefile(m, stderr, 10);
+ fputs("\nexpect = ", stderr); mp_writefile(r, stderr, 10);
+ fputs("\nresult = ", stderr); mp_writefile(y, stderr, 10);
+ ok = 0;
+ }
+ MP_DROP(x); MP_DROP(m); MP_DROP(r); MP_DROP(y);
+ assert(mparena_count(MPARENA_GLOBAL) == 0);
+ return (ok);
+}
+
static int gcd(dstr *v)
{
int ok = 1;
mp_gcd(&gg, &xx, &yy, a, b);
if (!MP_EQ(x, xx)) {
fputs("\n*** mp_gcd(x) failed", stderr);
- fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
- fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
+ fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
+ fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
fputs("\nexpect = ", stderr); mp_writefile(x, stderr, 10);
fputs("\nresult = ", stderr); mp_writefile(xx, stderr, 10);
fputc('\n', stderr);
}
if (!MP_EQ(y, yy)) {
fputs("\n*** mp_gcd(y) failed", stderr);
- fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
- fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
+ fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
+ fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
fputs("\nexpect = ", stderr); mp_writefile(y, stderr, 10);
fputs("\nresult = ", stderr); mp_writefile(yy, stderr, 10);
fputc('\n', stderr);
if (!MP_EQ(g, gg)) {
fputs("\n*** mp_gcd(gcd) failed", stderr);
- fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
- fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
+ fputs("\na = ", stderr); mp_writefile(a, stderr, 10);
+ fputs("\nb = ", stderr); mp_writefile(b, stderr, 10);
fputs("\nexpect = ", stderr); mp_writefile(g, stderr, 10);
fputs("\nresult = ", stderr); mp_writefile(gg, stderr, 10);
fputc('\n', stderr);
static test_chunk tests[] = {
{ "gcd", gcd, { &type_mp, &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
+ { "modinv", modinv, { &type_mp, &type_mp, &type_mp, 0 } },
{ 0, 0, { 0 } }
};