X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/f46efa79cd2bb9adc81541f1218965f85a6b2eef..e564e3f84ad0ea42b78559c0bfe304893fd5e76b:/f-niceprime.c

diff --git a/f-niceprime.c b/f-niceprime.c
index c34e24e..83b9ca5 100644
--- a/f-niceprime.c
+++ b/f-niceprime.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: f-niceprime.c,v 1.1 2004/03/27 00:04:46 mdw Exp $
+ * $Id$
  *
  * Prime fields with efficient reduction for special-form primes
  *
  * (c) 2004 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of Catacomb.
  *
@@ -15,172 +15,119 @@
  * 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,
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: f-niceprime.c,v $
- * Revision 1.1  2004/03/27 00:04:46  mdw
- * Implement efficient reduction for pleasant-looking primes.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <mLib/sub.h>
 
 #include "field.h"
-#include "mpreduce.h"
+#include "field-guts.h"
 #include "mprand.h"
 
-/*----- Data structures ---------------------------------------------------*/
-
-typedef struct fctx {
-  field f;
-  mpreduce r;
-} fctx;
-
 /*----- Main code ---------------------------------------------------------*/
 
 /* --- Field operations --- */
 
-static void fdestroy(field *ff)
-{
-  fctx *f = (fctx *)ff;
+static void fdestroy(field *ff) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
   mpreduce_destroy(&f->r);
   DESTROY(f);
 }
 
-static mp *frand(field *ff, mp *d, grand *r)
-{
-  fctx *f = (fctx *)ff;
+static mp *frand(field *ff, mp *d, grand *r) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
   return (mprand_range(d, f->r.p, r, 0));
 }
 
-static int fzerop(field *ff, mp *x)
-{
-  return (!MP_LEN(x));
-}
+static int fzerop(field *ff, mp *x) { return (MP_ZEROP(x)); }
 
-static mp *fneg(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
+static mp *fneg(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
   return (mp_sub(d, f->r.p, x));
 }
 
-static mp *fadd(field *ff, mp *d, mp *x, mp *y)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_add(d, x, y);
-  if (d->f & MP_NEG)
-    d = mp_add(d, d, f->r.p);
-  else if (MP_CMP(d, >, f->r.p))
-    d = mp_sub(d, d, f->r.p);
+static mp *fadd(field *ff, mp *d, mp *x, mp *y) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_add(d, x, y);
+  if (MP_NEGP(d)) d = mp_add(d, d, f->r.p);
+  else if (MP_CMP(d, >, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
-static mp *fsub(field *ff, mp *d, mp *x, mp *y)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_sub(d, x, y);
-  if (d->f & MP_NEG)
-    d = mp_add(d, d, f->r.p);
-  else if (MP_CMP(d, >, f->r.p))
-    d = mp_sub(d, d, f->r.p);
+static mp *fsub(field *ff, mp *d, mp *x, mp *y) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_sub(d, x, y);
+  if (MP_NEGP(d)) d = mp_add(d, d, f->r.p);
+  else if (MP_CMP(d, >, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
-static mp *fmul(field *ff, mp *d, mp *x, mp *y)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_mul(d, x, y);
+static mp *fmul(field *ff, mp *d, mp *x, mp *y) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_mul(d, x, y);
   return (mpreduce_do(&f->r, d, d));
 }
 
-static mp *fsqr(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_sqr(d, x);
+static mp *fsqr(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_sqr(d, x);
   return (mpreduce_do(&f->r, d, d));
 }
 
-static mp *finv(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  mp_gcd(0, 0, &d, f->r.p, x);
+static mp *finv(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
+  d = mp_modinv(d, x, f->r.p);
   return (d);
 }
 
-static mp *freduce(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
+static mp *freduce(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
   return (mpreduce_do(&f->r, d, x));
 }
 
-static mp *fsqrt(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
+static mp *fsqrt(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
   return (mp_modsqrt(d, x, f->r.p));
 }
 
-static mp *fdbl(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_lsl(d, x, 1);
-  if (MP_CMP(d, >, f->r.p))
-    d = mp_sub(d, d, f->r.p);
+static mp *fdbl(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_lsl(d, x, 1);
+  if (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
-static mp *ftpl(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  MP_DEST(d, MP_LEN(x) + 1, x->f);
-  MPX_UMULN(d->v, d->vl, x->v, x->vl, 3);
-  while (MP_CMP(d, >, f->r.p))
-    d = mp_sub(d, d, f->r.p);
+static mp *ftpl(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; MP_DEST(d, MP_LEN(x) + 1, x->f);
+  MPX_UMULN(d->v, d->vl, x->v, x->vl, 3); d->f &= ~MP_UNDEF;
+  while (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
-static mp *fqdl(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  d = mp_lsl(d, x, 2);
-  while (MP_CMP(d, >, f->r.p))
-    d = mp_sub(d, d, f->r.p);
+static mp *fqdl(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_lsl(d, x, 2);
+  while (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
-static mp *fhlv(field *ff, mp *d, mp *x)
-{
-  fctx *f = (fctx *)ff;
-  if (!MP_LEN(x)) {
-    MP_COPY(x);
-    MP_DROP(d);
-    return (x);
-  }
-  if (x->v[0] & 1) {
-    d = mp_add(d, x, f->r.p);
-    x = d;
-  }
+static mp *fhlv(field *ff, mp *d, mp *x) {
+  fctx_niceprime *f = (fctx_niceprime *)ff;
+  if (MP_ZEROP(x)) { MP_COPY(x); MP_DROP(d); return (x); }
+  if (x->v[0] & 1) { d = mp_add(d, x, f->r.p); x = d; }
   return (mp_lsr(d, x, 1));
 }
 
 /* --- Field operations table --- */
 
-static field_ops fops = {
+static const field_ops fops = {
   FTY_PRIME, "niceprime",
-  fdestroy, frand,
+  fdestroy, frand, field_stdsamep,
   freduce, field_id,
   fzerop, fneg, fadd, fsub, fmul, fsqr, finv, freduce, fsqrt,
   0,
@@ -191,7 +138,7 @@ static field_ops fops = {
  *
  * Arguments:	@mp *p@ = the characteristic of the field
  *
- * Returns:	A pointer to the field.
+ * Returns:	A pointer to the field, or null.
  *
  * Use:		Creates a field structure for a prime field of size %$p$%,
  *		using efficient reduction for nice primes.
@@ -199,11 +146,18 @@ static field_ops fops = {
 
 field *field_niceprime(mp *p)
 {
-  fctx *f = CREATE(fctx);
+  fctx_niceprime *f = CREATE(fctx_niceprime);
   f->f.ops = &fops;
   f->f.zero = MP_ZERO;
   f->f.one = MP_ONE;
-  mpreduce_create(&f->r, p);
+  f->f.nbits = mp_bits(p);
+  f->f.noctets = (f->f.nbits + 7) >> 3;
+  if (mpreduce_create(&f->r, p)) {
+    DESTROY(f);
+    return (0);
+  }
+  f->f.m = f->r.p;
+  f->f.q = f->r.p;
   return (&f->f);
 }