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kc3-lang/libtommath/bn_mp_reduce_is_2k_l.c

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  • Author : Tom St Denis
    Date : 2007-04-18 09:58:18
    Hash : 333aebc8
    Message : added libtommath-0.41

  • bn_mp_reduce_is_2k_l.c
  • #include <tommath.h>
    #ifdef BN_MP_REDUCE_IS_2K_L_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://libtom.org
     */
    
    /* determines if reduce_2k_l can be used */
    int mp_reduce_is_2k_l(mp_int *a)
    {
       int ix, iy;
       
       if (a->used == 0) {
          return MP_NO;
       } else if (a->used == 1) {
          return MP_YES;
       } else if (a->used > 1) {
          /* if more than half of the digits are -1 we're sold */
          for (iy = ix = 0; ix < a->used; ix++) {
              if (a->dp[ix] == MP_MASK) {
                  ++iy;
              }
          }
          return (iy >= (a->used/2)) ? MP_YES : MP_NO;
          
       }
       return MP_NO;
    }
    
    #endif
    
    /* $Source$ */
    /* $Revision$ */
    /* $Date$ */