1 /* mpi-cmp.c - MPI functions
2 * Copyright (C) 1998, 1999 Free Software Foundation, Inc.
3 *
4 * This file is part of GnuPG.
5 *
6 * GnuPG is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * GnuPG 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 General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * 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 "mpi-internal.h"
22
23 int mpi_cmp_ui(MPI u, unsigned long v)
24 {
25 mpi_limb_t limb = v;
26
27 mpi_normalize(u);
28 if (u->nlimbs == 0) {
29 if (v == 0)
30 return 0;
31 else
32 return -1;
33 }
34 if (u->sign)
35 return -1;
36 if (u->nlimbs > 1)
37 return 1;
38
39 if (u->d[0] == limb)
40 return 0;
41 else if (u->d[0] > limb)
42 return 1;
43 else
44 return -1;
45 }
46 EXPORT_SYMBOL_GPL(mpi_cmp_ui);
47
48 static int do_mpi_cmp(MPI u, MPI v, int absmode)
49 {
50 mpi_size_t usize;
51 mpi_size_t vsize;
52 int usign;
53 int vsign;
54 int cmp;
55
56 mpi_normalize(u);
57 mpi_normalize(v);
58
59 usize = u->nlimbs;
60 vsize = v->nlimbs;
61 usign = absmode ? 0 : u->sign;
62 vsign = absmode ? 0 : v->sign;
63
64 /* Compare sign bits. */
65
66 if (!usign && vsign)
67 return 1;
68 if (usign && !vsign)
69 return -1;
70
71 /* U and V are either both positive or both negative. */
72
73 if (usize != vsize && !usign && !vsign)
74 return usize - vsize;
75 if (usize != vsize && usign && vsign)
76 return vsize + usize;
77 if (!usize)
78 return 0;
79 cmp = mpihelp_cmp(u->d, v->d, usize);
80 if (!cmp)
81 return 0;
82 if ((cmp < 0?1:0) == (usign?1:0))
83 return 1;
84
85 return -1;
86 }
87
88 int mpi_cmp(MPI u, MPI v)
89 {
90 return do_mpi_cmp(u, v, 0);
91 }
92 EXPORT_SYMBOL_GPL(mpi_cmp);
93
94 int mpi_cmpabs(MPI u, MPI v)
95 {
96 return do_mpi_cmp(u, v, 1);
97 }
98 EXPORT_SYMBOL_GPL(mpi_cmpabs);
99
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