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comparison libtommath/bn_mp_decr.c @ 1692:1051e4eea25a

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Update LibTomMath to 1.2.0 (#84) * update C files * update other files * update headers * update makefiles * remove mp_set/get_double() * use ltm 1.2.0 API * update ltm_desc * use bundled tommath if system-tommath is too old * XMALLOC etc. were changed to MP_MALLOC etc.
author Steffen Jaeckel <s@jaeckel.eu>
date Tue, 26 May 2020 17:36:47 +0200
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1691:2d3745d58843 1692:1051e4eea25a
1 #include "tommath_private.h"
2 #ifdef BN_MP_DECR_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
4 /* SPDX-License-Identifier: Unlicense */
5
6 /* Decrement "a" by one like "a--". Changes input! */
7 mp_err mp_decr(mp_int *a)
8 {
9 if (MP_IS_ZERO(a)) {
10 mp_set(a,1uL);
11 a->sign = MP_NEG;
12 return MP_OKAY;
13 } else if (a->sign == MP_NEG) {
14 mp_err err;
15 a->sign = MP_ZPOS;
16 if ((err = mp_incr(a)) != MP_OKAY) {
17 return err;
18 }
19 /* There is no -0 in LTM */
20 if (!MP_IS_ZERO(a)) {
21 a->sign = MP_NEG;
22 }
23 return MP_OKAY;
24 } else if (a->dp[0] > 1uL) {
25 a->dp[0]--;
26 if (a->dp[0] == 0u) {
27 mp_zero(a);
28 }
29 return MP_OKAY;
30 } else {
31 return mp_sub_d(a, 1uL,a);
32 }
33 }
34 #endif