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cdec9cb5 DK |
1 | /* mpihelp-sub.c - MPI helper functions |
2 | * Copyright (C) 1994, 1996 Free Software Foundation, Inc. | |
3 | * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. | |
4 | * | |
5 | * This file is part of GnuPG. | |
6 | * | |
7 | * GnuPG is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * GnuPG is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA | |
20 | * | |
21 | * Note: This code is heavily based on the GNU MP Library. | |
22 | * Actually it's the same code with only minor changes in the | |
23 | * way the data is stored; this is to support the abstraction | |
24 | * of an optional secure memory allocation which may be used | |
25 | * to avoid revealing of sensitive data due to paging etc. | |
26 | * The GNU MP Library itself is published under the LGPL; | |
27 | * however I decided to publish this code under the plain GPL. | |
28 | */ | |
29 | ||
30 | #include "mpi-internal.h" | |
31 | ||
32 | /**************** | |
33 | * Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE. | |
34 | * There are no restrictions on the relative sizes of | |
35 | * the two arguments. | |
36 | * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2. | |
37 | */ | |
38 | int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size) | |
39 | { | |
40 | mpi_size_t i; | |
41 | mpi_limb_t op1_word, op2_word; | |
42 | ||
43 | for (i = size - 1; i >= 0; i--) { | |
44 | op1_word = op1_ptr[i]; | |
45 | op2_word = op2_ptr[i]; | |
46 | if (op1_word != op2_word) | |
47 | goto diff; | |
48 | } | |
49 | return 0; | |
50 | ||
51 | diff: | |
52 | /* This can *not* be simplified to | |
53 | * op2_word - op2_word | |
54 | * since that expression might give signed overflow. */ | |
55 | return (op1_word > op2_word) ? 1 : -1; | |
56 | } |