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comparison libtommath/bn_mp_sub.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_SUB_C 2 #ifdef BN_MP_SUB_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 /* high level subtraction (handles signs) */ 15 /* high level subtraction (handles signs) */
19 int 16 int mp_sub(const mp_int *a, const mp_int *b, mp_int *c)
20 mp_sub (mp_int * a, mp_int * b, mp_int * c)
21 { 17 {
22 int sa, sb, res; 18 int sa, sb, res;
23 19
24 sa = a->sign; 20 sa = a->sign;
25 sb = b->sign; 21 sb = b->sign;
26 22
27 if (sa != sb) { 23 if (sa != sb) {
28 /* subtract a negative from a positive, OR */ 24 /* subtract a negative from a positive, OR */
29 /* subtract a positive from a negative. */ 25 /* subtract a positive from a negative. */
30 /* In either case, ADD their magnitudes, */ 26 /* In either case, ADD their magnitudes, */
31 /* and use the sign of the first number. */ 27 /* and use the sign of the first number. */
32 c->sign = sa;
33 res = s_mp_add (a, b, c);
34 } else {
35 /* subtract a positive from a positive, OR */
36 /* subtract a negative from a negative. */
37 /* First, take the difference between their */
38 /* magnitudes, then... */
39 if (mp_cmp_mag (a, b) != MP_LT) {
40 /* Copy the sign from the first */
41 c->sign = sa; 28 c->sign = sa;
42 /* The first has a larger or equal magnitude */ 29 res = s_mp_add(a, b, c);
43 res = s_mp_sub (a, b, c); 30 } else {
44 } else { 31 /* subtract a positive from a positive, OR */
45 /* The result has the *opposite* sign from */ 32 /* subtract a negative from a negative. */
46 /* the first number. */ 33 /* First, take the difference between their */
47 c->sign = (sa == MP_ZPOS) ? MP_NEG : MP_ZPOS; 34 /* magnitudes, then... */
48 /* The second has a larger magnitude */ 35 if (mp_cmp_mag(a, b) != MP_LT) {
49 res = s_mp_sub (b, a, c); 36 /* Copy the sign from the first */
50 } 37 c->sign = sa;
51 } 38 /* The first has a larger or equal magnitude */
52 return res; 39 res = s_mp_sub(a, b, c);
40 } else {
41 /* The result has the *opposite* sign from */
42 /* the first number. */
43 c->sign = (sa == MP_ZPOS) ? MP_NEG : MP_ZPOS;
44 /* The second has a larger magnitude */
45 res = s_mp_sub(b, a, c);
46 }
47 }
48 return res;
53 } 49 }
54 50
55 #endif 51 #endif
56 52
57 /* ref: $Format:%D$ */ 53 /* ref: HEAD -> master, tag: v1.1.0 */
58 /* git commit: $Format:%H$ */ 54 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
59 /* commit time: $Format:%ai$ */ 55 /* commit time: 2019-01-28 20:32:32 +0100 */