| #include <tommath.h> |
| #ifdef BN_MP_REDUCE_2K_SETUP_C |
| /* LibTomMath, multiple-precision integer library -- Tom St Denis |
| * |
| * LibTomMath is a library that provides multiple-precision |
| * integer arithmetic as well as number theoretic functionality. |
| * |
| * The library was designed directly after the MPI library by |
| * Michael Fromberger but has been written from scratch with |
| * additional optimizations in place. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| * |
| * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com |
| */ |
| |
| /* determines the setup value */ |
| int mp_reduce_2k_setup(mp_int *a, mp_digit *d) |
| { |
| int res, p; |
| mp_int tmp; |
| |
| if ((res = mp_init(&tmp)) != MP_OKAY) { |
| return res; |
| } |
| |
| p = mp_count_bits(a); |
| if ((res = mp_2expt(&tmp, p)) != MP_OKAY) { |
| mp_clear(&tmp); |
| return res; |
| } |
| |
| if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) { |
| mp_clear(&tmp); |
| return res; |
| } |
| |
| *d = tmp.dp[0]; |
| mp_clear(&tmp); |
| return MP_OKAY; |
| } |
| #endif |
| |
| /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k_setup.c,v $ */ |
| /* $Revision: 1.3 $ */ |
| /* $Date: 2006/03/31 14:18:44 $ */ |
