2 #ifdef BN_MP_REDUCE_2K_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
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.
12 * The library is free for all purposes without any express
15 * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
18 /* reduces a modulo n where n is of the form 2**p - d */
19 int mp_reduce_2k(mp_int *a, mp_int *n, mp_digit d)
24 if ((res = mp_init(&q)) != MP_OKAY) {
30 /* q = a/2**p, a = a mod 2**p */
31 if ((res = mp_div_2d(a, p, &q, a)) != MP_OKAY) {
37 if ((res = mp_mul_d(&q, d, &q)) != MP_OKAY) {
43 if ((res = s_mp_add(a, &q, a)) != MP_OKAY) {
47 if (mp_cmp_mag(a, n) != MP_LT) {
59 /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k.c,v $ */
60 /* $Revision: 1.3 $ */
61 /* $Date: 2006/03/31 14:18:44 $ */