/src/dropbear/libtommath/bn_mp_mod.c
Line | Count | Source |
1 | | #include "tommath_private.h" |
2 | | #ifdef BN_MP_MOD_C |
3 | | /* LibTomMath, multiple-precision integer library -- Tom St Denis */ |
4 | | /* SPDX-License-Identifier: Unlicense */ |
5 | | |
6 | | /* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */ |
7 | | mp_err mp_mod(const mp_int *a, const mp_int *b, mp_int *c) |
8 | 236k | { |
9 | 236k | mp_int t; |
10 | 236k | mp_err err; |
11 | | |
12 | 236k | if ((err = mp_init_size(&t, b->used)) != MP_OKAY) { |
13 | 0 | return err; |
14 | 0 | } |
15 | | |
16 | 236k | if ((err = mp_div(a, b, NULL, &t)) != MP_OKAY) { |
17 | 0 | goto LBL_ERR; |
18 | 0 | } |
19 | | |
20 | 236k | if (MP_IS_ZERO(&t) || (t.sign == b->sign)) { |
21 | 235k | err = MP_OKAY; |
22 | 235k | mp_exch(&t, c); |
23 | 235k | } else { |
24 | 444 | err = mp_add(b, &t, c); |
25 | 444 | } |
26 | | |
27 | 236k | LBL_ERR: |
28 | 236k | mp_clear(&t); |
29 | 236k | return err; |
30 | 236k | } |
31 | | #endif |