mpih-cmp.c
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/* mpihelp-sub.c - MPI helper functions
* Copyright (C) 1994, 1996 Free Software Foundation, Inc.
* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG 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 General Public License for more details.
*
* You should have received a copy of the GNU 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
*
* Note: This code is heavily based on the GNU MP Library.
* Actually it's the same code with only minor changes in the
* way the data is stored; this is to support the abstraction
* of an optional secure memory allocation which may be used
* to avoid revealing of sensitive data due to paging etc.
* The GNU MP Library itself is published under the LGPL;
* however I decided to publish this code under the plain GPL.
*/
#include "mpi-internal.h"
/****************
* Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.
* There are no restrictions on the relative sizes of
* the two arguments.
* Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.
*/
int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size)
{
mpi_size_t i;
mpi_limb_t op1_word, op2_word;
for (i = size - 1; i >= 0; i--) {
op1_word = op1_ptr[i];
op2_word = op2_ptr[i];
if (op1_word != op2_word)
goto diff;
}
return 0;
diff:
/* This can *not* be simplified to
* op2_word - op2_word
* since that expression might give signed overflow. */
return (op1_word > op2_word) ? 1 : -1;
}