1 // endian/detail/intrinsic.hpp -------------------------------------------------------// 2 3 // Copyright (C) 2012 David Stone 4 // Copyright Beman Dawes 2013 5 6 // Distributed under the Boost Software License, Version 1.0. 7 // http://www.boost.org/LICENSE_1_0.txt 8 9 #ifndef BOOST_ENDIAN_INTRINSIC_HPP 10 #define BOOST_ENDIAN_INTRINSIC_HPP 11 12 // Allow user to force BOOST_ENDIAN_NO_INTRINSICS in case they aren't available for a 13 // particular platform/compiler combination. Please report such platform/compiler 14 // combinations to the Boost mailing list. 15 #ifndef BOOST_ENDIAN_NO_INTRINSICS 16 17 #ifndef __has_builtin // Optional of course 18 #define __has_builtin(x) 0 // Compatibility with non-clang compilers 19 #endif 20 21 #if defined(_MSC_VER) && ( !defined(__clang__) || defined(__c2__) ) 22 // Microsoft documents these as being compatible since Windows 95 and specifically 23 // lists runtime library support since Visual Studio 2003 (aka 7.1). 24 // Clang/c2 uses the Microsoft rather than GCC intrinsics, so we check for 25 // defined(_MSC_VER) before defined(__clang__) 26 # define BOOST_ENDIAN_INTRINSIC_MSG "cstdlib _byteswap_ushort, etc." 27 # include <cstdlib> 28 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) _byteswap_ushort(x) 29 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) _byteswap_ulong(x) 30 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) _byteswap_uint64(x) 31 32 // GCC and Clang recent versions provide intrinsic byte swaps via builtins 33 #elif (defined(__clang__) && __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)) \ 34 || (defined(__GNUC__ ) && \ 35 (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))) 36 # define BOOST_ENDIAN_INTRINSIC_MSG "__builtin_bswap16, etc." 37 // prior to 4.8, gcc did not provide __builtin_bswap16 on some platforms so we emulate it 38 // see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624 39 // Clang has a similar problem, but their feature test macros make it easier to detect 40 # if (defined(__clang__) && __has_builtin(__builtin_bswap16)) \ 41 || (defined(__GNUC__) &&(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) 42 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap16(x) 43 # else 44 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap32((x) << 16) 45 # endif 46 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) __builtin_bswap32(x) 47 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) __builtin_bswap64(x) 48 49 # define BOOST_ENDIAN_CONSTEXPR_INTRINSICS 50 51 // Linux systems provide the byteswap.h header, with 52 #elif defined(__linux__) 53 // don't check for obsolete forms defined(linux) and defined(__linux) on the theory that 54 // compilers that predefine only these are so old that byteswap.h probably isn't present. 55 # define BOOST_ENDIAN_INTRINSIC_MSG "byteswap.h bswap_16, etc." 56 # include <byteswap.h> 57 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) bswap_16(x) 58 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) bswap_32(x) 59 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) bswap_64(x) 60 61 #else 62 # define BOOST_ENDIAN_NO_INTRINSICS 63 # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics" 64 #endif 65 66 #elif !defined(BOOST_ENDIAN_INTRINSIC_MSG) 67 # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics" 68 #endif // BOOST_ENDIAN_NO_INTRINSICS 69 #endif // BOOST_ENDIAN_INTRINSIC_HPP 70