/* -*-c-*-
*
- * $Id: f-prime.c,v 1.3 2003/05/15 23:25:59 mdw Exp $
+ * $Id: f-prime.c,v 1.3.4.1 2003/06/10 13:43:53 mdw Exp $
*
* Prime fields with Montgomery arithmetic
*
/*----- Revision history --------------------------------------------------*
*
* $Log: f-prime.c,v $
+ * Revision 1.3.4.1 2003/06/10 13:43:53 mdw
+ * Simple (non-projective) curves over prime fields now seem to work.
+ *
* Revision 1.3 2003/05/15 23:25:59 mdw
* Make elliptic curve stuff build.
*
static mp *fin(field *ff, mp *d, mp *x)
{
fctx *f = (fctx *)ff;
- return (mpmont_mul(&f->mm, d, x, f->mm.r2));
+ mp_div(0, &d, x, f->mm.m);
+ return (mpmont_mul(&f->mm, d, d, f->mm.r2));
}
static mp *fout(field *ff, mp *d, mp *x)
static mp *fadd(field *ff, mp *d, mp *x, mp *y)
{
- return (mp_add(d, x, y));
+ fctx *f = (fctx *)ff;
+ d = mp_add(d, x, y);
+ if (d->f & MP_NEG)
+ d = mp_add(d, d, f->mm.m);
+ else if (MP_CMP(d, >, f->mm.m))
+ d = mp_sub(d, d, f->mm.m);
+ return (d);
}
static mp *fsub(field *ff, mp *d, mp *x, mp *y)
{
- return (mp_sub(d, x, y));
+ fctx *f = (fctx *)ff;
+ d = mp_sub(d, x, y);
+ if (d->f & MP_NEG)
+ d = mp_add(d, d, f->mm.m);
+ else if (MP_CMP(d, >, f->mm.m))
+ d = mp_sub(d, d, f->mm.m);
+ return (d);
}
static mp *fmul(field *ff, mp *d, mp *x, mp *y)
static mp *fdbl(field *ff, mp *d, mp *x)
{
-/* fctx *f = (fctx *)ff; */
- return (mp_lsl(d, x, 1));
+ fctx *f = (fctx *)ff;
+ d = mp_lsl(d, x, 1);
+ if (MP_CMP(d, >, f->mm.m))
+ d = mp_sub(d, d, f->mm.m);
+ return (d);
}
static mp *ftpl(field *ff, mp *d, mp *x)
{
-/* fctx *f = (fctx *)ff; */
+ 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->mm.m))
+ d = mp_sub(d, d, f->mm.m);
return (d);
}