libgcrypt-1.4.6/mpi/mpi-cmp.c

/* mpi-cmp.c  -  MPI functions
 * Copyright (C) 1998, 1999, 2001, 2002, 2005 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"

int
gcry_mpi_cmp_ui (gcry_mpi_t u, unsigned long v)
{
  mpi_limb_t limb = v;

  _gcry_mpi_normalize (u);

  /* Handle the case that U contains no limb.  */
  if (u->nlimbs == 0)
    return -(limb != 0);

  /* Handle the case that U is negative.  */
  if (u->sign)
    return -1;

  if (u->nlimbs == 1)
    {
      /* Handle the case that U contains exactly one limb.  */

      if (u->d[0] > limb)
	return 1;
      if (u->d[0] < limb)
	return -1;
      return 0;
    }
  else
    /* Handle the case that U contains more than one limb.  */
    return 1;
}

int
gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)
{
  mpi_size_t usize;
  mpi_size_t vsize;
  int cmp;

  _gcry_mpi_normalize (u);
  _gcry_mpi_normalize (v);

  usize = u->nlimbs;
  vsize = v->nlimbs;

  /* Compare sign bits.  */

  if (!u->sign && v->sign)
    return 1;
  if (u->sign && !v->sign)
    return -1;

  /* U and V are either both positive or both negative.  */

  if( usize != vsize && !u->sign && !v->sign )
    return usize - vsize;
  if( usize != vsize && u->sign && v->sign )
    return vsize + usize;
  if( !usize )
    return 0;
  if( !(cmp = _gcry_mpih_cmp( u->d, v->d, usize )) )
    return 0;
  if( (cmp < 0?1:0) == (u->sign?1:0))
    return 1;

  return -1;
}