/* -*-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.
*
* 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,
*
* 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.
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);
}
projects / u / mdw / catacomb / blobdiff