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comparison bn_mp_prime_is_divisible.c @ 2:86e0b50a9b58 libtommath-orig ltm-0.30-orig

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ltm 0.30 orig import
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:22 +0000
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-1:000000000000 2:86e0b50a9b58
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* determines if an integers is divisible by one
18 * of the first PRIME_SIZE primes or not
19 *
20 * sets result to 0 if not, 1 if yes
21 */
22 int mp_prime_is_divisible (mp_int * a, int *result)
23 {
24 int err, ix;
25 mp_digit res;
26
27 /* default to not */
28 *result = MP_NO;
29
30 for (ix = 0; ix < PRIME_SIZE; ix++) {
31 /* what is a mod __prime_tab[ix] */
32 if ((err = mp_mod_d (a, __prime_tab[ix], &res)) != MP_OKAY) {
33 return err;
34 }
35
36 /* is the residue zero? */
37 if (res == 0) {
38 *result = MP_YES;
39 return MP_OKAY;
40 }
41 }
42
43 return MP_OKAY;
44 }