c3-lang/libtommath/bn_mp_reduce_is_2k.c

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• Hash : e45f75fd
  Author :
  Date : 2019-04-13T08:46:57
  

  deprecate DIGIT_BIT, use MP_DIGIT_BIT

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• bn_mp_reduce_is_2k.c

• #include "tommath_private.h"
  #ifdef BN_MP_REDUCE_IS_2K_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* determines if mp_reduce_2k can be used */
  int mp_reduce_is_2k(const mp_int *a)
  {
     int ix, iy, iw;
     mp_digit iz;
  
     if (a->used == 0) {
        return MP_NO;
     } else if (a->used == 1) {
        return MP_YES;
     } else if (a->used > 1) {
        iy = mp_count_bits(a);
        iz = 1;
        iw = 1;
  
        /* Test every bit from the second digit up, must be 1 */
        for (ix = MP_DIGIT_BIT; ix < iy; ix++) {
           if ((a->dp[iw] & iz) == 0u) {
              return MP_NO;
           }
           iz <<= 1;
           if (iz > (mp_digit)MP_MASK) {
              ++iw;
              iz = 1;
           }
        }
     }
     return MP_YES;
  }
  
  #endif
  

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