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Giac_maj/libtommath-0.39/bn_mp_prime_is_divisible.c 1.25 KB
6663b6c9   adorian   projet complet av...
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  #include <tommath.h>
  #ifdef BN_MP_PRIME_IS_DIVISIBLE_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 if an integers is divisible by one 
   * of the first PRIME_SIZE primes or not
   *
   * sets result to 0 if not, 1 if yes
   */
  int mp_prime_is_divisible (mp_int * a, int *result)
  {
    int     err, ix;
    mp_digit res;
  
    /* default to not */
    *result = MP_NO;
  
    for (ix = 0; ix < PRIME_SIZE; ix++) {
      /* what is a mod LBL_prime_tab[ix] */
      if ((err = mp_mod_d (a, ltm_prime_tab[ix], &res)) != MP_OKAY) {
        return err;
      }
  
      /* is the residue zero? */
      if (res == 0) {
        *result = MP_YES;
        return MP_OKAY;
      }
    }
  
    return MP_OKAY;
  }
  #endif
  
  /* $Source: /cvs/libtom/libtommath/bn_mp_prime_is_divisible.c,v $ */
  /* $Revision: 1.3 $ */
  /* $Date: 2006/03/31 14:18:44 $ */