// SPDX-License-Identifier: GPL-2.0-or-later
/* 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.
 *
 * 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;
}