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comparison libtommath/bn_mp_montgomery_setup.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
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1691:2d3745d58843 1692:1051e4eea25a
1 #include "tommath_private.h" 1 #include "tommath_private.h"
2 #ifdef BN_MP_MONTGOMERY_SETUP_C 2 #ifdef BN_MP_MONTGOMERY_SETUP_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 /* setups the montgomery reduction stuff */ 6 /* setups the montgomery reduction stuff */
16 int mp_montgomery_setup(const mp_int *n, mp_digit *rho) 7 mp_err mp_montgomery_setup(const mp_int *n, mp_digit *rho)
17 { 8 {
18 mp_digit x, b; 9 mp_digit x, b;
19 10
20 /* fast inversion mod 2**k 11 /* fast inversion mod 2**k
21 * 12 *
42 #ifdef MP_64BIT 33 #ifdef MP_64BIT
43 x *= 2u - (b * x); /* here x*a==1 mod 2**64 */ 34 x *= 2u - (b * x); /* here x*a==1 mod 2**64 */
44 #endif 35 #endif
45 36
46 /* rho = -1/m mod b */ 37 /* rho = -1/m mod b */
47 *rho = (mp_digit)(((mp_word)1 << (mp_word)DIGIT_BIT) - x) & MP_MASK; 38 *rho = (mp_digit)(((mp_word)1 << (mp_word)MP_DIGIT_BIT) - x) & MP_MASK;
48 39
49 return MP_OKAY; 40 return MP_OKAY;
50 } 41 }
51 #endif 42 #endif
52
53 /* ref: HEAD -> master, tag: v1.1.0 */
54 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
55 /* commit time: 2019-01-28 20:32:32 +0100 */