1 /* $NetBSD: bn_mp_reduce_is_2k_l.c,v 1.2 2017/01/28 21:31:47 christos Exp $ */ 2 3 #include <tommath.h> 4 #ifdef BN_MP_REDUCE_IS_2K_L_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 /* determines if reduce_2k_l can be used */ mp_reduce_is_2k_l(mp_int * a)21int mp_reduce_is_2k_l(mp_int *a) 22 { 23 int ix, iy; 24 25 if (a->used == 0) { 26 return MP_NO; 27 } else if (a->used == 1) { 28 return MP_YES; 29 } else if (a->used > 1) { 30 /* if more than half of the digits are -1 we're sold */ 31 for (iy = ix = 0; ix < a->used; ix++) { 32 if (a->dp[ix] == MP_MASK) { 33 ++iy; 34 } 35 } 36 return (iy >= (a->used/2)) ? MP_YES : MP_NO; 37 38 } 39 return MP_NO; 40 } 41 42 #endif 43 44 /* Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k_l.c,v */ 45 /* Revision: 1.4 */ 46 /* Date: 2006/12/28 01:25:13 */ 47