Mercurial > dropbear

comparison bn_mp_reduce_2k_setup.c @ 282:91fbc376f010 libtommath-orig libtommath-0.35

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Import of libtommath 0.35 From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:16:18 +0000
parents
children 97db060d0ef5
comparison
equal deleted inserted replaced
-1:000000000000 282:91fbc376f010
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.org
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