libtommath/bn_mp_mod.c
2019-04-07 17:26:31 +02:00

32 lines
660 B
C

#include "tommath_private.h"
#ifdef BN_MP_MOD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */
int mp_mod(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_int t;
int res;
if ((res = mp_init_size(&t, b->used)) != MP_OKAY) {
return res;
}
if ((res = mp_div(a, b, NULL, &t)) != MP_OKAY) {
mp_clear(&t);
return res;
}
if (IS_ZERO(&t) || (t.sign == b->sign)) {
res = MP_OKAY;
mp_exch(&t, c);
} else {
res = mp_add(b, &t, c);
}
mp_clear(&t);
return res;
}
#endif