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comparison libtommath/bn_mp_reduce_2k_setup.c @ 389:5ff8218bcee9

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propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e) to branch 'au.asn.ucc.matt.dropbear' (head ecd779509ef23a8cdf64888904fc9b31d78aa933)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 03:14:55 +0000
parents eed26cff980b
children 60fc6476e044
comparison
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388:fb54020f78e1 389:5ff8218bcee9
1 #include <tommath.h>
2 #ifdef BN_MP_REDUCE_2K_SETUP_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
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 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com
16 */
17
18 /* determines the setup value */
19 int mp_reduce_2k_setup(mp_int *a, mp_digit *d)
20 {
21 int res, p;
22 mp_int tmp;
23
24 if ((res = mp_init(&tmp)) != MP_OKAY) {
25 return res;
26 }
27
28 p = mp_count_bits(a);
29 if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
30 mp_clear(&tmp);
31 return res;
32 }
33
34 if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
35 mp_clear(&tmp);
36 return res;
37 }
38
39 *d = tmp.dp[0];
40 mp_clear(&tmp);
41 return MP_OKAY;
42 }
43 #endif
44
45 /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k_setup.c,v $ */
46 /* $Revision: 1.3 $ */
47 /* $Date: 2006/03/31 14:18:44 $ */