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comparison bn_mp_reduce.c @ 142:d29b64170cf0 libtommath-orig

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import of libtommath 0.32
author Matt Johnston <matt@ucc.asn.au>
date Sun, 19 Dec 2004 11:33:56 +0000
parents 86e0b50a9b58
children d8254fc979e9
comparison
equal deleted inserted replaced
19:e1037a1e12e7 142:d29b64170cf0
1 #include <tommath.h>
2 #ifdef BN_MP_REDUCE_C
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 * 4 *
3 * LibTomMath is a library that provides multiple-precision 5 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality. 6 * integer arithmetic as well as number theoretic functionality.
5 * 7 *
10 * The library is free for all purposes without any express 12 * The library is free for all purposes without any express
11 * guarantee it works. 13 * guarantee it works.
12 * 14 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org 15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */ 16 */
15 #include <tommath.h>
16 17
17 /* reduces x mod m, assumes 0 < x < m**2, mu is 18 /* reduces x mod m, assumes 0 < x < m**2, mu is
18 * precomputed via mp_reduce_setup. 19 * precomputed via mp_reduce_setup.
19 * From HAC pp.604 Algorithm 14.42 20 * From HAC pp.604 Algorithm 14.42
20 */ 21 */
36 if (((unsigned long) um) > (((mp_digit)1) << (DIGIT_BIT - 1))) { 37 if (((unsigned long) um) > (((mp_digit)1) << (DIGIT_BIT - 1))) {
37 if ((res = mp_mul (&q, mu, &q)) != MP_OKAY) { 38 if ((res = mp_mul (&q, mu, &q)) != MP_OKAY) {
38 goto CLEANUP; 39 goto CLEANUP;
39 } 40 }
40 } else { 41 } else {
42 #ifdef BN_S_MP_MUL_HIGH_DIGS_C
41 if ((res = s_mp_mul_high_digs (&q, mu, &q, um - 1)) != MP_OKAY) { 43 if ((res = s_mp_mul_high_digs (&q, mu, &q, um - 1)) != MP_OKAY) {
42 goto CLEANUP; 44 goto CLEANUP;
43 } 45 }
46 #elif defined(BN_FAST_S_MP_MUL_HIGH_DIGS_C)
47 if ((res = fast_s_mp_mul_high_digs (&q, mu, &q, um - 1)) != MP_OKAY) {
48 goto CLEANUP;
49 }
50 #else
51 {
52 res = MP_VAL;
53 goto CLEANUP;
54 }
55 #endif
44 } 56 }
45 57
46 /* q3 = q2 / b**(k+1) */ 58 /* q3 = q2 / b**(k+1) */
47 mp_rshd (&q, um + 1); 59 mp_rshd (&q, um + 1);
48 60
80 CLEANUP: 92 CLEANUP:
81 mp_clear (&q); 93 mp_clear (&q);
82 94
83 return res; 95 return res;
84 } 96 }
97 #endif