/* -*-c-*-
*
- * $Id: mpmont.c,v 1.10 2000/07/29 17:05:43 mdw Exp $
+ * $Id: mpmont.c,v 1.12 2000/10/08 15:48:35 mdw Exp $
*
* Montgomery reduction
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mpmont.c,v $
+ * Revision 1.12 2000/10/08 15:48:35 mdw
+ * Rename Karatsuba constants now that we have @gfx_kmul@ too.
+ *
+ * Revision 1.11 2000/10/08 12:04:27 mdw
+ * (mpmont_reduce, mpmont_mul): Cope with negative numbers.
+ *
* Revision 1.10 2000/07/29 17:05:43 mdw
* (mpmont_expr): Use sliding window exponentiation, with a drop-through
* for small exponents to use a simple left-to-right bitwise routine. This
/* --- Check for serious Karatsuba reduction --- */
- if (n > KARATSUBA_CUTOFF * 3) {
+ if (n > MPK_THRESH * 3) {
mp al;
mpw *vl;
mp *u;
memmove(d->v, d->v + n, MPWS(MP_LEN(d) - n));
d->vl -= n;
- if (MP_CMP(d, >=, mm->m))
- d = mp_sub(d, d, mm->m);
+ if (MPX_UCMP(d->v, d->vl, >=, mm->m->v, mm->m->vl))
+ mpx_usub(d->v, d->vl, d->v, d->vl, mm->m->v, mm->m->vl);
+ if (d->f & MP_NEG) {
+ mpx_usub(d->v, d->vl, mm->m->v, mm->m->vl, d->v, d->vl);
+ d->f &= ~MP_NEG;
+ }
MP_SHRINK(d);
return (d);
}
mp *mpmont_mul(mpmont *mm, mp *d, mp *a, mp *b)
{
- if (mm->n > KARATSUBA_CUTOFF * 3) {
+ if (mm->n > MPK_THRESH * 3) {
d = mp_mul(d, a, b);
d = mpmont_reduce(mm, d, d);
} else {
memmove(d->v, dv, MPWS(dvl - dv));
d->vl -= dv - d->v;
+ if (MPX_UCMP(d->v, d->vl, >=, mm->m->v, mm->m->vl))
+ mpx_usub(d->v, d->vl, d->v, d->vl, mm->m->v, mm->m->vl);
+ if ((a->f ^ b->f) & MP_NEG)
+ mpx_usub(d->v, d->vl, mm->m->v, mm->m->vl, d->v, d->vl);
MP_SHRINK(d);
d->f = (a->f | b->f) & MP_BURN;
- if (MP_CMP(d, >=, mm->m))
- d = mp_sub(d, d, mm->m);
MP_DROP(a);
MP_DROP(b);
}
ok = 0;
}
- if (MP_CMP(mm.r, !=, r)) {
+ if (!MP_EQ(mm.r, r)) {
fputs("\n*** bad r", stderr);
fputs("\nm = ", stderr); mp_writefile(m, stderr, 10);
fputs("\nexpected ", stderr); mp_writefile(r, stderr, 10);
ok = 0;
}
- if (MP_CMP(mm.r2, !=, r2)) {
+ if (!MP_EQ(mm.r2, r2)) {
fputs("\n*** bad r2", stderr);
fputs("\nm = ", stderr); mp_writefile(m, stderr, 10);
fputs("\nexpected ", stderr); mp_writefile(r2, stderr, 10);
mp *qr = mp_mul(MP_NEW, a, b);
mp_div(0, &qr, qr, m);
- if (MP_CMP(qr, !=, r)) {
+ if (!MP_EQ(qr, r)) {
fputs("\n*** classical modmul failed", stderr);
fputs("\n m = ", stderr); mp_writefile(m, stderr, 10);
fputs("\n a = ", stderr); mp_writefile(a, stderr, 10);
mp *br = mpmont_mul(&mm, MP_NEW, b, mm.r2);
mp *mr = mpmont_mul(&mm, MP_NEW, ar, br);
mr = mpmont_reduce(&mm, mr, mr);
- if (MP_CMP(mr, !=, r)) {
+ if (!MP_EQ(mr, r)) {
fputs("\n*** montgomery modmul failed", stderr);
fputs("\n m = ", stderr); mp_writefile(m, stderr, 10);
fputs("\n a = ", stderr); mp_writefile(a, stderr, 10);
mr = mpmont_exp(&mm, MP_NEW, a, b);
- if (MP_CMP(mr, !=, r)) {
+ if (!MP_EQ(mr, r)) {
fputs("\n*** montgomery modexp failed", stderr);
fputs("\n m = ", stderr); mp_writefile(m, stderr, 10);
fputs("\n a = ", stderr); mp_writefile(a, stderr, 10);