1 #include <tommath.h> 2 #ifdef BN_MP_REDUCE_IS_2K_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 /* determines if mp_reduce_2k can be used */ 19 int mp_reduce_is_2k(mp_int *a) 20 { 21 int ix, iy, iw; 22 mp_digit iz; 23 24 if (a->used == 0) { 25 return MP_NO; 26 } else if (a->used == 1) { 27 return MP_YES; 28 } else if (a->used > 1) { 29 iy = mp_count_bits(a); 30 iz = 1; 31 iw = 1; 32 33 /* Test every bit from the second digit up, must be 1 */ 34 for (ix = DIGIT_BIT; ix < iy; ix++) { 35 if ((a->dp[iw] & iz) == 0) { 36 return MP_NO; 37 } 38 iz <<= 1; 39 if (iz > (mp_digit)MP_MASK) { 40 ++iw; 41 iz = 1; 42 } 43 } 44 } 45 return MP_YES; 46 } 47 48 #endif 49 50 /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k.c,v $ */ 51 /* $Revision: 1.3 $ */ 52 /* $Date: 2006/03/31 14:18:44 $ */ 53
