1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* mpihelp-sub.c - MPI helper functions 3 * 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 the 10 * way the data is stored; this is to support the abstraction 11 * of an optional secure memory allocation which may be used 12 * 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 of 22 * the two arguments. 23 * Return 1 if OP1 > OP2, 0 if they are equal, and -1 if OP1 < OP2. 24 */ 25 int 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 38 diff: 39 /* This can *not* be simplified to 40 * op2_word - op2_word 41 * since that expression might give signed overflow. */ 42 return (op1_word > op2_word) ? 1 : -1; 43 } 44