millerrabin_safe_trial.c

/*
 * Copyright 2008 2009 2010 2011 2013 Torbjorn Granlund, Douglas Wikstrom
 *
 * This file is part of GMP Modular Exponentiation Extension (GMPMEE).
 *
 * GMPMEE is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * GMPMEE is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GMPMEE. If not, see <http://www.gnu.org/licenses/>.
 */

#include <gmp.h>
#include "gmpmee.h"

int
gmpmee_millerrabin_safe_trial(mpz_t n)
{
  mp_limb_t r;
  int res = 1;

  mpz_t m;

  /* Odd or smaller than 5. */
  if (mpz_tstbit(n, 0) == 0 || mpz_cmp_ui(n, 5) < 0)
    {
      res = 0;
    }
  else
    {

      mpz_init(m);
      mpz_tdiv_q_2exp (m, n, 1); /* m = (n-1)/2 */

#if __SIZEOF_INT__ == 4
#include "trialdiv_safe_32.c"
#elif __SIZEOF_INT__ == 8
#include "trialdiv_safe_64.c"
#endif

      mpz_clear(m);
    }
  return res;
}