libtommath/bn_mp_mod.c
2019-09-03 05:45:33 +02:00

32 lines
657 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 */
mp_err mp_mod(const mp_int *a, const mp_int *b, mp_int *c)
{
mp_int t;
mp_err err;
if ((err = mp_init_size(&t, b->used)) != MP_OKAY) {
return err;
}
if ((err = mp_div(a, b, NULL, &t)) != MP_OKAY) {
goto LBL_ERR;
}
if (MP_IS_ZERO(&t) || (t.sign == b->sign)) {
err = MP_OKAY;
mp_exch(&t, c);
} else {
err = mp_add(b, &t, c);
}
LBL_ERR:
mp_clear(&t);
return err;
}
#endif