/* 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;

}

/* Helper for _gcry_mpi_cmp and _gcry_mpi_cmpabs.  */

static int

do_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v, int absmode)

{

  mpi_size_t usize;

  mpi_size_t vsize;

  int usign;

  int vsign;

  int cmp;

  if (mpi_is_opaque (u) || mpi_is_opaque (v))

    {

      /* We have no signan and thus ABSMODE has no efeect here.  */

      if (mpi_is_opaque (u) && !mpi_is_opaque (v))

        return -1;

      if (!mpi_is_opaque (u) && mpi_is_opaque (v))

        return 1;

      if (!u->sign && !v->sign)

        return 0; /* Empty buffers are identical.  */

      if (u->sign < v->sign)

        return -1;

      if (u->sign > v->sign)

        return 1;

      return memcmp (u->d, v->d, (u->sign+7)/8);

    }

  else

    {

      _gcry_mpi_normalize (u);

      _gcry_mpi_normalize (v);

      usize = u->nlimbs;

      vsize = v->nlimbs;

      usign = absmode? 0 : u->sign;

      vsign = absmode? 0 : v->sign;

      /* Special treatment for +0 == -0 */

      if (!usize && !vsize)

        return 0;

      /* Compare sign bits.  */

      if (!usign && vsign)

        return 1;

      if (usign && !vsign)

        return -1;

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

      if (usize != vsize && !usign && !vsign)

        return usize - vsize;

      if (usize != vsize && usign && vsign)

        return vsize + usize;

      if (!usize )

        return 0;

      if (!(cmp = _gcry_mpih_cmp (u->d, v->d, usize)))

        return 0;

      if ((cmp < 0?1:0) == (usign?1:0))

        return 1;

    }

  return -1;

}

int

_gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)

{

  return do_mpi_cmp (u, v, 0);

}

/* Compare only the absolute values.  */

int

_gcry_mpi_cmpabs (gcry_mpi_t u, gcry_mpi_t v)

{

  return do_mpi_cmp (u, v, 1);

}