From a02032a37c71fcbe35796781d3dad8ff068ca611 Mon Sep 17 00:00:00 2001
From: mdw <mdw>
Date: Sat, 5 Mar 2005 16:43:25 +0000
Subject: [PATCH] Add some fast paths for standard operations.

---
 ec.c | 51 ++++++++++++++++++++++-----------------------------
 1 file changed, 22 insertions(+), 29 deletions(-)

diff --git a/ec.c b/ec.c
index a84dd7a..e5e1c87 100644
--- a/ec.c
+++ b/ec.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec.c,v 1.10 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
  *
  * Elliptic curve definitions
  *
@@ -46,7 +46,8 @@
 
 int ec_samep(ec_curve *c, ec_curve *d)
 {
-  return (field_samep(c->f, d->f) && c->ops == d->ops && EC_SAMEP(c, d));
+  return (c == d || (field_samep(c->f, d->f) &&
+		     c->ops == d->ops && EC_SAMEP(c, d)));
 }
 
 /* --- @ec_create@ --- *
@@ -127,9 +128,7 @@ int ec_eq(const ec *p, const ec *q) { return (EC_EQ(p, q)); }
  */
 
 int ec_stdsamep(ec_curve *c, ec_curve *d)
-{
-  return (MP_EQ(c->a, d->a) && MP_EQ(c->b, d->b));
-}
+  { return (MP_EQ(c->a, d->a) && MP_EQ(c->b, d->b)); }
 
 /* --- @ec_idin@, @ec_idout@, @ec_idfix@ --- *
  *
@@ -171,10 +170,7 @@ ec *ec_idout(ec_curve *c, ec *d, const ec *p)
 }
 
 ec *ec_idfix(ec_curve *c, ec *d, const ec *p)
-{
-  EC_COPY(d, p);
-  return (d);
-}
+  { EC_COPY(d, p); return (d); }
 
 /* --- @ec_projin@, @ec_projout@, @ec_projfix@ --- *
  *
@@ -208,16 +204,21 @@ ec *ec_projout(ec_curve *c, ec *d, const ec *p)
   else {
     mp *x, *y, *z, *zz;
     field *f = c->f;
-    z = F_INV(f, MP_NEW, p->z);
-    zz = F_SQR(f, MP_NEW, z);
-    z = F_MUL(f, z, zz, z);
-    x = F_MUL(f, d->x, p->x, zz);
-    y = F_MUL(f, d->y, p->y, z);
-    mp_drop(z);
-    mp_drop(zz);
+    if (p->z == f->one) {
+      d->x = F_OUT(f, d->x, p->x);
+      d->y = F_OUT(f, d->y, p->y);
+    } else {
+      z = F_INV(f, MP_NEW, p->z);
+      zz = F_SQR(f, MP_NEW, z);
+      z = F_MUL(f, z, zz, z);
+      x = F_MUL(f, d->x, p->x, zz);
+      y = F_MUL(f, d->y, p->y, z);
+      mp_drop(z);
+      mp_drop(zz);
+      d->x = F_OUT(f, x, x);
+      d->y = F_OUT(f, y, y);
+    }
     mp_drop(d->z);
-    d->x = F_OUT(f, x, x);
-    d->y = F_OUT(f, y, y);
     d->z = 0;
   }
   return (d);
@@ -227,7 +228,7 @@ ec *ec_projfix(ec_curve *c, ec *d, const ec *p)
 {
   if (EC_ATINF(p))
     EC_SETINF(d);
-  else if (d->z == c->f->one)
+  else if (p->z == c->f->one)
     EC_COPY(d, p);
   else {
     mp *z, *zz;
@@ -315,11 +316,7 @@ ec *ec_find(ec_curve *c, ec *d, mp *x)
  */
 
 ec *ec_neg(ec_curve *c, ec *d, const ec *p)
-{
-  EC_IN(c, d, p);
-  EC_NEG(c, d, d);
-  return (EC_OUT(c, d, d));
-}
+  { EC_IN(c, d, p); EC_NEG(c, d, d); return (EC_OUT(c, d, d)); }
 
 /* --- @ec_add@ --- *
  *
@@ -379,11 +376,7 @@ ec *ec_sub(ec_curve *c, ec *d, const ec *p, const ec *q)
  */
 
 ec *ec_dbl(ec_curve *c, ec *d, const ec *p)
-{
-  EC_IN(c, d, p);
-  EC_DBL(c, d, d);
-  return (EC_OUT(c, d, d));
-}
+  { EC_IN(c, d, p); EC_DBL(c, d, d); return (EC_OUT(c, d, d)); }
 
 /* --- @ec_check@ --- *
  *
-- 
2.11.0