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comparison libtommath/bn_mp_add_d.c @ 1655:f52919ffd3b1

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update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79) * make key-generation compliant to FIPS 186.4 * fix includes in tommath_class.h * update fuzzcorpus instead of error-out * fixup fuzzing make-targets * update Makefile.in * apply necessary patches to ltm sources * clean-up not required ltm files * update to vanilla ltm 1.1.0 this already only contains the required files * remove set/get double
author Steffen Jaeckel <s_jaeckel@gmx.de>
date Mon, 16 Sep 2019 15:50:38 +0200
parents 8bba51a55704
children 1051e4eea25a
comparison
equal deleted inserted replaced
1654:cc0fc5131c5c 1655:f52919ffd3b1
1 #include <tommath_private.h> 1 #include "tommath_private.h"
2 #ifdef BN_MP_ADD_D_C 2 #ifdef BN_MP_ADD_D_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 * 4 *
5 * LibTomMath is a library that provides multiple-precision 5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality. 6 * integer arithmetic as well as number theoretic functionality.
7 * 7 *
8 * The library was designed directly after the MPI library by 8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with 9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place. 10 * additional optimizations in place.
11 * 11 *
12 * The library is free for all purposes without any express 12 * SPDX-License-Identifier: Unlicense
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://libtom.org
16 */ 13 */
17 14
18 /* single digit addition */ 15 /* single digit addition */
19 int 16 int mp_add_d(const mp_int *a, mp_digit b, mp_int *c)
20 mp_add_d (mp_int * a, mp_digit b, mp_int * c)
21 { 17 {
22 int res, ix, oldused; 18 int res, ix, oldused;
23 mp_digit *tmpa, *tmpc, mu; 19 mp_digit *tmpa, *tmpc, mu;
24 20
25 /* grow c as required */ 21 /* grow c as required */
26 if (c->alloc < (a->used + 1)) { 22 if (c->alloc < (a->used + 1)) {
27 if ((res = mp_grow(c, a->used + 1)) != MP_OKAY) { 23 if ((res = mp_grow(c, a->used + 1)) != MP_OKAY) {
28 return res; 24 return res;
29 } 25 }
30 } 26 }
31 27
32 /* if a is negative and |a| >= b, call c = |a| - b */ 28 /* if a is negative and |a| >= b, call c = |a| - b */
33 if ((a->sign == MP_NEG) && ((a->used > 1) || (a->dp[0] >= b))) { 29 if ((a->sign == MP_NEG) && ((a->used > 1) || (a->dp[0] >= b))) {
34 /* temporarily fix sign of a */ 30 mp_int a_ = *a;
35 a->sign = MP_ZPOS; 31 /* temporarily fix sign of a */
32 a_.sign = MP_ZPOS;
36 33
37 /* c = |a| - b */ 34 /* c = |a| - b */
38 res = mp_sub_d(a, b, c); 35 res = mp_sub_d(&a_, b, c);
39 36
40 /* fix sign */ 37 /* fix sign */
41 a->sign = c->sign = MP_NEG; 38 c->sign = MP_NEG;
42 39
43 /* clamp */ 40 /* clamp */
44 mp_clamp(c); 41 mp_clamp(c);
45 42
46 return res; 43 return res;
47 } 44 }
48 45
49 /* old number of used digits in c */ 46 /* old number of used digits in c */
50 oldused = c->used; 47 oldused = c->used;
51 48
52 /* source alias */ 49 /* source alias */
53 tmpa = a->dp; 50 tmpa = a->dp;
54 51
55 /* destination alias */ 52 /* destination alias */
56 tmpc = c->dp; 53 tmpc = c->dp;
57 54
58 /* if a is positive */ 55 /* if a is positive */
59 if (a->sign == MP_ZPOS) { 56 if (a->sign == MP_ZPOS) {
60 /* add digit, after this we're propagating 57 /* add digit, after this we're propagating
61 * the carry. 58 * the carry.
62 */ 59 */
63 *tmpc = *tmpa++ + b; 60 *tmpc = *tmpa++ + b;
64 mu = *tmpc >> DIGIT_BIT; 61 mu = *tmpc >> DIGIT_BIT;
65 *tmpc++ &= MP_MASK; 62 *tmpc++ &= MP_MASK;
66 63
67 /* now handle rest of the digits */ 64 /* now handle rest of the digits */
68 for (ix = 1; ix < a->used; ix++) { 65 for (ix = 1; ix < a->used; ix++) {
69 *tmpc = *tmpa++ + mu; 66 *tmpc = *tmpa++ + mu;
70 mu = *tmpc >> DIGIT_BIT; 67 mu = *tmpc >> DIGIT_BIT;
71 *tmpc++ &= MP_MASK; 68 *tmpc++ &= MP_MASK;
72 } 69 }
73 /* set final carry */ 70 /* set final carry */
74 ix++; 71 ix++;
75 *tmpc++ = mu; 72 *tmpc++ = mu;
76 73
77 /* setup size */ 74 /* setup size */
78 c->used = a->used + 1; 75 c->used = a->used + 1;
79 } else { 76 } else {
80 /* a was negative and |a| < b */ 77 /* a was negative and |a| < b */
81 c->used = 1; 78 c->used = 1;
82 79
83 /* the result is a single digit */ 80 /* the result is a single digit */
84 if (a->used == 1) { 81 if (a->used == 1) {
85 *tmpc++ = b - a->dp[0]; 82 *tmpc++ = b - a->dp[0];
86 } else { 83 } else {
87 *tmpc++ = b; 84 *tmpc++ = b;
88 } 85 }
89 86
90 /* setup count so the clearing of oldused 87 /* setup count so the clearing of oldused
91 * can fall through correctly 88 * can fall through correctly
92 */ 89 */
93 ix = 1; 90 ix = 1;
94 } 91 }
95 92
96 /* sign always positive */ 93 /* sign always positive */
97 c->sign = MP_ZPOS; 94 c->sign = MP_ZPOS;
98 95
99 /* now zero to oldused */ 96 /* now zero to oldused */
100 while (ix++ < oldused) { 97 while (ix++ < oldused) {
101 *tmpc++ = 0; 98 *tmpc++ = 0;
102 } 99 }
103 mp_clamp(c); 100 mp_clamp(c);
104 101
105 return MP_OKAY; 102 return MP_OKAY;
106 } 103 }
107 104
108 #endif 105 #endif
109 106
110 /* ref: $Format:%D$ */ 107 /* ref: HEAD -> master, tag: v1.1.0 */
111 /* git commit: $Format:%H$ */ 108 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
112 /* commit time: $Format:%ai$ */ 109 /* commit time: 2019-01-28 20:32:32 +0100 */