1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /* mpihelp-sub.c - MPI helper functions
3*4882a593Smuzhiyun * Copyright (C) 1994, 1996 Free Software Foundation, Inc.
4*4882a593Smuzhiyun * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
5*4882a593Smuzhiyun *
6*4882a593Smuzhiyun * This file is part of GnuPG.
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * Note: This code is heavily based on the GNU MP Library.
9*4882a593Smuzhiyun * Actually it's the same code with only minor changes in the
10*4882a593Smuzhiyun * way the data is stored; this is to support the abstraction
11*4882a593Smuzhiyun * of an optional secure memory allocation which may be used
12*4882a593Smuzhiyun * to avoid revealing of sensitive data due to paging etc.
13*4882a593Smuzhiyun * The GNU MP Library itself is published under the LGPL;
14*4882a593Smuzhiyun * however I decided to publish this code under the plain GPL.
15*4882a593Smuzhiyun */
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #include "mpi-internal.h"
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun /****************
20*4882a593Smuzhiyun * Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.
21*4882a593Smuzhiyun * There are no restrictions on the relative sizes of
22*4882a593Smuzhiyun * the two arguments.
23*4882a593Smuzhiyun * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.
24*4882a593Smuzhiyun */
mpihelp_cmp(mpi_ptr_t op1_ptr,mpi_ptr_t op2_ptr,mpi_size_t size)25*4882a593Smuzhiyun int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun mpi_size_t i;
28*4882a593Smuzhiyun mpi_limb_t op1_word, op2_word;
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun for (i = size - 1; i >= 0; i--) {
31*4882a593Smuzhiyun op1_word = op1_ptr[i];
32*4882a593Smuzhiyun op2_word = op2_ptr[i];
33*4882a593Smuzhiyun if (op1_word != op2_word)
34*4882a593Smuzhiyun goto diff;
35*4882a593Smuzhiyun }
36*4882a593Smuzhiyun return 0;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun diff:
39*4882a593Smuzhiyun /* This can *not* be simplified to
40*4882a593Smuzhiyun * op2_word - op2_word
41*4882a593Smuzhiyun * since that expression might give signed overflow. */
42*4882a593Smuzhiyun return (op1_word > op2_word) ? 1 : -1;
43*4882a593Smuzhiyun }
44