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comparison libtommath/bn_mp_mod.c @ 284:eed26cff980b

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propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
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children 5ff8218bcee9
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283:bd240aa12ba7 284:eed26cff980b
1 #include <tommath.h>
2 #ifdef BN_MP_MOD_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 /* c = a mod b, 0 <= c < b */
19 int
20 mp_mod (mp_int * a, mp_int * b, mp_int * c)
21 {
22 mp_int t;
23 int res;
24
25 if ((res = mp_init (&t)) != MP_OKAY) {
26 return res;
27 }
28
29 if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
30 mp_clear (&t);
31 return res;
32 }
33
34 if (t.sign != b->sign) {
35 res = mp_add (b, &t, c);
36 } else {
37 res = MP_OKAY;
38 mp_exch (&t, c);
39 }
40
41 mp_clear (&t);
42 return res;
43 }
44 #endif