1 #include <tommath.h> 2 #ifdef BN_MP_INVMOD_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, tomstdenis (at) gmail.com, http://math.libtomcrypt.com 16 */ 17 18 /* hac 14.61, pp608 */ 19 int mp_invmod (mp_int * a, mp_int * b, mp_int * c) 20 { 21 /* b cannot be negative */ 22 if (b->sign == MP_NEG || mp_iszero(b) == 1) { 23 return MP_VAL; 24 } 25 26 #ifdef BN_FAST_MP_INVMOD_C 27 /* if the modulus is odd we can use a faster routine instead */ 28 if (mp_isodd (b) == 1) { 29 return fast_mp_invmod (a, b, c); 30 } 31 #endif 32 33 #ifdef BN_MP_INVMOD_SLOW_C 34 return mp_invmod_slow(a, b, c); 35 #endif 36 37 return MP_VAL; 38 } 39 #endif 40 41 /* $Source: /cvs/libtom/libtommath/bn_mp_invmod.c,v $ */ 42 /* $Revision: 1.3 $ */ 43 /* $Date: 2006/03/31 14:18:44 $ */ 44
