1/* $NetBSD: bn_mp_mod.c,v 1.2 2017/01/28 21:31:47 christos Exp $ */ 2 3#include <tommath.h> 4#ifdef BN_MP_MOD_C 5/* LibTomMath, multiple-precision integer library -- Tom St Denis 6 * 7 * LibTomMath is a library that provides multiple-precision 8 * integer arithmetic as well as number theoretic functionality. 9 * 10 * The library was designed directly after the MPI library by 11 * Michael Fromberger but has been written from scratch with 12 * additional optimizations in place. 13 * 14 * The library is free for all purposes without any express 15 * guarantee it works. 16 * 17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org 18 */ 19 20/* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */ 21int 22mp_mod (mp_int * a, mp_int * b, mp_int * c) 23{ 24 mp_int t; 25 int res; 26 27 if ((res = mp_init (&t)) != MP_OKAY) { 28 return res; 29 } 30 31 if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) { 32 mp_clear (&t); 33 return res; 34 } 35 36 if (mp_iszero(&t) || t.sign == b->sign) { 37 res = MP_OKAY; 38 mp_exch (&t, c); 39 } else { 40 res = mp_add (b, &t, c); 41 } 42 43 mp_clear (&t); 44 return res; 45} 46#endif 47 48/* Source: /cvs/libtom/libtommath/bn_mp_mod.c,v */ 49/* Revision: 1.4 */ 50/* Date: 2006/12/28 01:25:13 */ 51