1/* mpi-cmp.c  -  MPI functions
2 * Copyright (C) 1998, 1999, 2001, 2002, 2005 Free Software Foundation, Inc.
3 *
4 * This file is part of Libgcrypt.
5 *
6 * Libgcrypt is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation; either version 2.1 of
9 * the License, or (at your option) any later version.
10 *
11 * Libgcrypt is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19 */
20
21#include <config.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include "mpi-internal.h"
25
26int
27gcry_mpi_cmp_ui (gcry_mpi_t u, unsigned long v)
28{
29  mpi_limb_t limb = v;
30
31  _gcry_mpi_normalize (u);
32
33  /* Handle the case that U contains no limb.  */
34  if (u->nlimbs == 0)
35    return -(limb != 0);
36
37  /* Handle the case that U is negative.  */
38  if (u->sign)
39    return -1;
40
41  if (u->nlimbs == 1)
42    {
43      /* Handle the case that U contains exactly one limb.  */
44
45      if (u->d[0] > limb)
46	return 1;
47      if (u->d[0] < limb)
48	return -1;
49      return 0;
50    }
51  else
52    /* Handle the case that U contains more than one limb.  */
53    return 1;
54}
55
56
57int
58gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)
59{
60  mpi_size_t usize;
61  mpi_size_t vsize;
62  int cmp;
63
64  if (mpi_is_opaque (u) || mpi_is_opaque (v))
65    {
66      if (mpi_is_opaque (u) && !mpi_is_opaque (v))
67        return -1;
68      if (!mpi_is_opaque (u) && mpi_is_opaque (v))
69        return 1;
70      if (!u->sign && !v->sign)
71        return 0; /* Empty buffers are identical.  */
72      if (u->sign < v->sign)
73        return -1;
74      if (u->sign > v->sign)
75        return 1;
76      return memcmp (u->d, v->d, (u->sign+7)/8);
77    }
78  else
79    {
80      _gcry_mpi_normalize (u);
81      _gcry_mpi_normalize (v);
82
83      usize = u->nlimbs;
84      vsize = v->nlimbs;
85
86      /* Compare sign bits.  */
87
88      if (!u->sign && v->sign)
89        return 1;
90      if (u->sign && !v->sign)
91        return -1;
92
93      /* U and V are either both positive or both negative.  */
94
95      if (usize != vsize && !u->sign && !v->sign)
96        return usize - vsize;
97      if (usize != vsize && u->sign && v->sign)
98        return vsize + usize;
99      if (!usize )
100        return 0;
101      if (!(cmp = _gcry_mpih_cmp (u->d, v->d, usize)))
102        return 0;
103      if ((cmp < 0?1:0) == (u->sign?1:0))
104        return 1;
105    }
106  return -1;
107}
108