| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 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 | } |