| // endian/detail/intrinsic.hpp -------------------------------------------------------// |
| |
| // Copyright (C) 2012 David Stone |
| // Copyright Beman Dawes 2013 |
| |
| // Distributed under the Boost Software License, Version 1.0. |
| // http://www.boost.org/LICENSE_1_0.txt |
| |
| #ifndef BOOST_ENDIAN_INTRINSIC_HPP |
| #define BOOST_ENDIAN_INTRINSIC_HPP |
| |
| // Allow user to force BOOST_ENDIAN_NO_INTRINSICS in case they aren't available for a |
| // particular platform/compiler combination. Please report such platform/compiler |
| // combinations to the Boost mailing list. |
| #ifndef BOOST_ENDIAN_NO_INTRINSICS |
| |
| #ifndef __has_builtin // Optional of course |
| #define __has_builtin(x) 0 // Compatibility with non-clang compilers |
| #endif |
| |
| // GCC and Clang recent versions provide intrinsic byte swaps via builtins |
| #if (defined(__clang__) && __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)) \ |
| || (defined(__GNUC__ ) && \ |
| (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))) |
| # define BOOST_ENDIAN_INTRINSIC_MSG "__builtin_bswap16, etc." |
| // prior to 4.8, gcc did not provide __builtin_bswap16 on some platforms so we emulate it |
| // see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624 |
| // Clang has a similar problem, but their feature test macros make it easier to detect |
| # if (defined(__clang__) && __has_builtin(__builtin_bswap16)) \ |
| || (defined(__GNUC__) &&(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap16(x) |
| # else |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap32((x) << 16) |
| # endif |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) __builtin_bswap32(x) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) __builtin_bswap64(x) |
| |
| // Linux systems provide the byteswap.h header, with |
| #elif defined(__linux__) |
| // don't check for obsolete forms defined(linux) and defined(__linux) on the theory that |
| // compilers that predefine only these are so old that byteswap.h probably isn't present. |
| # define BOOST_ENDIAN_INTRINSIC_MSG "byteswap.h bswap_16, etc." |
| # include <byteswap.h> |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) bswap_16(x) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) bswap_32(x) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) bswap_64(x) |
| |
| #elif defined(_MSC_VER) |
| // Microsoft documents these as being compatible since Windows 95 and specificly |
| // lists runtime library support since Visual Studio 2003 (aka 7.1). |
| # define BOOST_ENDIAN_INTRINSIC_MSG "cstdlib _byteswap_ushort, etc." |
| # include <cstdlib> |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) _byteswap_ushort(x) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) _byteswap_ulong(x) |
| # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) _byteswap_uint64(x) |
| #else |
| # define BOOST_ENDIAN_NO_INTRINSICS |
| # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics" |
| #endif |
| |
| #elif !defined(BOOST_ENDIAN_INTRINSIC_MSG) |
| # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics" |
| #endif // BOOST_ENDIAN_NO_INTRINSICS |
| #endif // BOOST_ENDIAN_INTRINSIC_HPP |