/* mpi-gcd.c  -  MPI functions

 *  Copyright (C) 1998, 2001, 2002, 2003 Free Software Foundation, Inc.

 *

 * This file is part of Libgcrypt.

 *

 * Libgcrypt is free software; you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * Libgcrypt 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

 */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#include "mpi-internal.h"

/****************

 * Find the greatest common divisor G of A and B.

 * Return: true if this 1, false in all other cases

 */

int

_gcry_mpi_gcd (gcry_mpi_t g, gcry_mpi_t xa, gcry_mpi_t xb)

{

    gcry_mpi_t a, b;

    a = mpi_copy(xa);

    b = mpi_copy(xb);

    /* TAOCP Vol II, 4.5.2, Algorithm A */

    a->sign = 0;

    b->sign = 0;

    while (mpi_cmp_ui (b, 0))

      {

  _gcry_mpi_fdiv_r( g, a, b ); /* G is used as temporary variable. */

  mpi_set(a,b);

  mpi_set(b,g);

      }

    mpi_set(g, a);

    mpi_free(a);

    mpi_free(b);

    return !mpi_cmp_ui( g, 1);

}