1 /* 2 * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #ifndef OSSL_INTERNAL_ENDIAN_H 11 # define OSSL_INTERNAL_ENDIAN_H 12 # pragma once 13 14 /* 15 * IS_LITTLE_ENDIAN and IS_BIG_ENDIAN can be used to detect the endiannes 16 * at compile time. To use it, DECLARE_IS_ENDIAN must be used to declare 17 * a variable. 18 * 19 * L_ENDIAN and B_ENDIAN can be used at preprocessor time. They can be set 20 * in the configarion using the lib_cppflags variable. If neither is 21 * set, it will fall back to code works with either endianness. 22 */ 23 24 # if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) 25 # define DECLARE_IS_ENDIAN const int ossl_is_little_endian = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ 26 # define IS_LITTLE_ENDIAN (ossl_is_little_endian) 27 # define IS_BIG_ENDIAN (!ossl_is_little_endian) 28 # if defined(L_ENDIAN) && (__BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__) 29 # error "L_ENDIAN defined on a big endian machine" 30 # endif 31 # if defined(B_ENDIAN) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) 32 # error "B_ENDIAN defined on a little endian machine" 33 # endif 34 # if !defined(L_ENDIAN) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) 35 # define L_ENDIAN 36 # endif 37 # if !defined(B_ENDIAN) && (__BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__) 38 # define B_ENDIAN 39 # endif 40 # else 41 # define DECLARE_IS_ENDIAN \ 42 const union { \ 43 long one; \ 44 char little; \ 45 } ossl_is_endian = { 1 } 46 47 # define IS_LITTLE_ENDIAN (ossl_is_endian.little != 0) 48 # define IS_BIG_ENDIAN (ossl_is_endian.little == 0) 49 # endif 50 51 #endif 52