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/* 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);
}