44 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/* mpihelp-sub.c - MPI helper functions3 * Copyright (C) 1994, 1996 Free Software Foundation, Inc.4 * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.5 *6 * This file is part of GnuPG.7 *8 * Note: This code is heavily based on the GNU MP Library.9 * Actually it's the same code with only minor changes in the10 * way the data is stored; this is to support the abstraction11 * of an optional secure memory allocation which may be used12 * to avoid revealing of sensitive data due to paging etc.13 * The GNU MP Library itself is published under the LGPL;14 * however I decided to publish this code under the plain GPL.15 */16 17#include "mpi-internal.h"18 19/****************20 * Compare OP1_PTR/OP1_SIZE with OP2_PTR/OP2_SIZE.21 * There are no restrictions on the relative sizes of22 * the two arguments.23 * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2.24 */25int mpihelp_cmp(mpi_ptr_t op1_ptr, mpi_ptr_t op2_ptr, mpi_size_t size)26{27 mpi_size_t i;28 mpi_limb_t op1_word, op2_word;29 30 for (i = size - 1; i >= 0; i--) {31 op1_word = op1_ptr[i];32 op2_word = op2_ptr[i];33 if (op1_word != op2_word)34 goto diff;35 }36 return 0;37 38diff:39 /* This can *not* be simplified to40 * op2_word - op2_word41 * since that expression might give signed overflow. */42 return (op1_word > op2_word) ? 1 : -1;43}44