/* -*-c-*-
*
- * $Id: mpreduce.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
*
* Efficient reduction modulo nice primes
*
/* --- Fill in the easy stuff --- */
- assert(MP_ISPOS(p));
+ assert(MP_POSP(p));
d = mp_bits(p);
r->lim = d/MPW_BITS;
r->s = d%MPW_BITS;
/* --- If source is negative, divide --- */
- if (MP_ISNEG(x)) {
+ if (MP_NEGP(x)) {
mp_div(0, &d, x, r->p);
return (d);
}
mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
MP_SHRINK(e);
- if (!MP_LEN(e))
+ MP_COPY(a);
+ if (MP_ZEROP(e))
;
- else if (MP_LEN(e) < EXP_THRESH)
- EXP_SIMPLE(x, a, e);
- else
- EXP_WINDOW(x, a, e);
+ else {
+ if (MP_NEGP(e))
+ a = mp_modinv(a, a, mr->p);
+ if (MP_LEN(e) < EXP_THRESH)
+ EXP_SIMPLE(x, a, e);
+ else
+ EXP_WINDOW(x, a, e);
+ }
+ mp_drop(a);
mp_drop(d);
mp_drop(spare);
return (x);