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comparison libtommath/bn_mp_mod_2d.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
parents f52919ffd3b1
children
comparison
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1691:2d3745d58843 1692:1051e4eea25a
1 #include "tommath_private.h" 1 #include "tommath_private.h"
2 #ifdef BN_MP_MOD_2D_C 2 #ifdef BN_MP_MOD_2D_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
4 * 4 /* SPDX-License-Identifier: Unlicense */
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * SPDX-License-Identifier: Unlicense
13 */
14 5
15 /* calc a value mod 2**b */ 6 /* calc a value mod 2**b */
16 int mp_mod_2d(const mp_int *a, int b, mp_int *c) 7 mp_err mp_mod_2d(const mp_int *a, int b, mp_int *c)
17 { 8 {
18 int x, res; 9 int x;
10 mp_err err;
19 11
20 /* if b is <= 0 then zero the int */ 12 /* if b is <= 0 then zero the int */
21 if (b <= 0) { 13 if (b <= 0) {
22 mp_zero(c); 14 mp_zero(c);
23 return MP_OKAY; 15 return MP_OKAY;
24 } 16 }
25 17
26 /* if the modulus is larger than the value than return */ 18 /* if the modulus is larger than the value than return */
27 if (b >= (a->used * DIGIT_BIT)) { 19 if (b >= (a->used * MP_DIGIT_BIT)) {
28 res = mp_copy(a, c); 20 return mp_copy(a, c);
29 return res;
30 } 21 }
31 22
32 /* copy */ 23 /* copy */
33 if ((res = mp_copy(a, c)) != MP_OKAY) { 24 if ((err = mp_copy(a, c)) != MP_OKAY) {
34 return res; 25 return err;
35 } 26 }
36 27
37 /* zero digits above the last digit of the modulus */ 28 /* zero digits above the last digit of the modulus */
38 for (x = (b / DIGIT_BIT) + (((b % DIGIT_BIT) == 0) ? 0 : 1); x < c->used; x++) { 29 x = (b / MP_DIGIT_BIT) + (((b % MP_DIGIT_BIT) == 0) ? 0 : 1);
39 c->dp[x] = 0; 30 MP_ZERO_DIGITS(c->dp + x, c->used - x);
40 } 31
41 /* clear the digit that is not completely outside/inside the modulus */ 32 /* clear the digit that is not completely outside/inside the modulus */
42 c->dp[b / DIGIT_BIT] &= 33 c->dp[b / MP_DIGIT_BIT] &=
43 ((mp_digit)1 << (mp_digit)(b % DIGIT_BIT)) - (mp_digit)1; 34 ((mp_digit)1 << (mp_digit)(b % MP_DIGIT_BIT)) - (mp_digit)1;
44 mp_clamp(c); 35 mp_clamp(c);
45 return MP_OKAY; 36 return MP_OKAY;
46 } 37 }
47 #endif 38 #endif
48
49 /* ref: HEAD -> master, tag: v1.1.0 */
50 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
51 /* commit time: 2019-01-28 20:32:32 +0100 */