summaryrefslogtreecommitdiffstats
path: root/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_submod.c
blob: 5ebd374986adee67825fcb4d199443a5e7ccbbfd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
#include "tommath_private.h"
#ifdef BN_MP_SUBMOD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* d = a - b (mod c) */
mp_err mp_submod(const mp_int *a, const mp_int *b, const mp_int *c, mp_int *d)
{
   mp_err err;
   mp_int t;

   if ((err = mp_init(&t)) != MP_OKAY) {
      return err;
   }

   if ((err = mp_sub(a, b, &t)) != MP_OKAY) {
      goto LBL_ERR;
   }
   err = mp_mod(&t, c, d);

LBL_ERR:
   mp_clear(&t);
   return err;
}
#endif