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kc3-lang/libtommath/bn_mp_reduce_2k_setup.c

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  • Author : Daniel Mendler
    Date : 2019-04-07 15:29:11
    Hash : ff561404
    Message : shorter headers

  • bn_mp_reduce_2k_setup.c
  • #include "tommath_private.h"
    #ifdef BN_MP_REDUCE_2K_SETUP_C
    /* LibTomMath, multiple-precision integer library -- Tom St Denis */
    /* SPDX-License-Identifier: Unlicense */
    
    /* determines the setup value */
    int mp_reduce_2k_setup(const 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