gcd: General tidying up.

[u/mdw/catacomb] / gf-gcd.c

diff --git a/gf-gcd.c b/gf-gcd.c
index 622679a..048d29d 100644 (file)
--- a/gf-gcd.c
+++ b/gf-gcd.c
@@ -106,15 +106,7 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
     return;
   }
 
-  /* --- Take a reference to the arguments --- */
-
-  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;
+  /* --- Main extended Euclidean algorithm --- */
 
   u = MP_COPY(a);
   v = MP_COPY(b);
@@ -124,10 +116,10 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
     gf_div(&q, &u, u, v);
     if (f & f_ext) {
       t = gf_mul(MP_NEW, X, q);
-      t = gf_add(t, x, t);
+      t = gf_add(t, t, x);
       MP_DROP(x); x = X; X = t;
       t = gf_mul(MP_NEW, Y, q);
-      t = gf_add(t, y, t);
+      t = gf_add(t, t, y);
       MP_DROP(y); y = Y; Y = t;
     }
     t = u; u = v; v = t;
@@ -172,7 +164,6 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
 
   MP_DROP(v);
   MP_DROP(X); MP_DROP(Y);
-  MP_DROP(a); MP_DROP(b);
 }
 
 /* -- @gf_modinv@ --- *