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comparison libtommath/bn_s_mp_add.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
equal deleted inserted replaced
1691:2d3745d58843 1692:1051e4eea25a
1 #include "tommath_private.h" 1 #include "tommath_private.h"
2 #ifdef BN_S_MP_ADD_C 2 #ifdef BN_S_MP_ADD_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 /* low level addition, based on HAC pp.594, Algorithm 14.7 */ 6 /* low level addition, based on HAC pp.594, Algorithm 14.7 */
16 int s_mp_add(const mp_int *a, const mp_int *b, mp_int *c) 7 mp_err s_mp_add(const mp_int *a, const mp_int *b, mp_int *c)
17 { 8 {
18 const mp_int *x; 9 const mp_int *x;
19 int olduse, res, min, max; 10 mp_err err;
11 int olduse, min, max;
20 12
21 /* find sizes, we let |a| <= |b| which means we have to sort 13 /* find sizes, we let |a| <= |b| which means we have to sort
22 * them. "x" will point to the input with the most digits 14 * them. "x" will point to the input with the most digits
23 */ 15 */
24 if (a->used > b->used) { 16 if (a->used > b->used) {
31 x = b; 23 x = b;
32 } 24 }
33 25
34 /* init result */ 26 /* init result */
35 if (c->alloc < (max + 1)) { 27 if (c->alloc < (max + 1)) {
36 if ((res = mp_grow(c, max + 1)) != MP_OKAY) { 28 if ((err = mp_grow(c, max + 1)) != MP_OKAY) {
37 return res; 29 return err;
38 } 30 }
39 } 31 }
40 32
41 /* get old used digit count and set new one */ 33 /* get old used digit count and set new one */
42 olduse = c->used; 34 olduse = c->used;
62 for (i = 0; i < min; i++) { 54 for (i = 0; i < min; i++) {
63 /* Compute the sum at one digit, T[i] = A[i] + B[i] + U */ 55 /* Compute the sum at one digit, T[i] = A[i] + B[i] + U */
64 *tmpc = *tmpa++ + *tmpb++ + u; 56 *tmpc = *tmpa++ + *tmpb++ + u;
65 57
66 /* U = carry bit of T[i] */ 58 /* U = carry bit of T[i] */
67 u = *tmpc >> (mp_digit)DIGIT_BIT; 59 u = *tmpc >> (mp_digit)MP_DIGIT_BIT;
68 60
69 /* take away carry bit from T[i] */ 61 /* take away carry bit from T[i] */
70 *tmpc++ &= MP_MASK; 62 *tmpc++ &= MP_MASK;
71 } 63 }
72 64
77 for (; i < max; i++) { 69 for (; i < max; i++) {
78 /* T[i] = X[i] + U */ 70 /* T[i] = X[i] + U */
79 *tmpc = x->dp[i] + u; 71 *tmpc = x->dp[i] + u;
80 72
81 /* U = carry bit of T[i] */ 73 /* U = carry bit of T[i] */
82 u = *tmpc >> (mp_digit)DIGIT_BIT; 74 u = *tmpc >> (mp_digit)MP_DIGIT_BIT;
83 75
84 /* take away carry bit from T[i] */ 76 /* take away carry bit from T[i] */
85 *tmpc++ &= MP_MASK; 77 *tmpc++ &= MP_MASK;
86 } 78 }
87 } 79 }
88 80
89 /* add carry */ 81 /* add carry */
90 *tmpc++ = u; 82 *tmpc++ = u;
91 83
92 /* clear digits above oldused */ 84 /* clear digits above oldused */
93 for (i = c->used; i < olduse; i++) { 85 MP_ZERO_DIGITS(tmpc, olduse - c->used);
94 *tmpc++ = 0;
95 }
96 } 86 }
97 87
98 mp_clamp(c); 88 mp_clamp(c);
99 return MP_OKAY; 89 return MP_OKAY;
100 } 90 }
101 #endif 91 #endif
102
103 /* ref: HEAD -> master, tag: v1.1.0 */
104 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
105 /* commit time: 2019-01-28 20:32:32 +0100 */