X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/a69a3efddbe1261f55e90d4ff477053ab80663a5..45c0fd363937c6e9b05da04a9167e9912c05ca0c:/mp-gcd.c

diff --git a/mp-gcd.c b/mp-gcd.c
index d997072..2583c8e 100644
--- a/mp-gcd.c
+++ b/mp-gcd.c
@@ -7,7 +7,7 @@
  * (c) 1999 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,12 +15,12 @@
  * 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,
@@ -118,19 +118,19 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
     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);
 
+  /* --- Main extended Euclidean algorithm --- */
+
   while (!MP_ZEROP(v)) {
     mp *t;
     mp_div(&q, &u, u, v);
@@ -254,6 +254,27 @@ mp *mp_modinv(mp *d, mp *x, mp *p)
 
 #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;
@@ -267,8 +288,8 @@ static int gcd(dstr *v)
   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);
@@ -276,8 +297,8 @@ static int gcd(dstr *v)
   }
   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);
@@ -296,8 +317,8 @@ static int gcd(dstr *v)
 
   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);
@@ -311,6 +332,7 @@ static int gcd(dstr *v)
 
 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 } }
 };