Chris@102: //  endian/detail/intrinsic.hpp  -------------------------------------------------------//
Chris@102: 
Chris@102: //  Copyright (C) 2012 David Stone
Chris@102: //  Copyright Beman Dawes 2013
Chris@102: 
Chris@102: //  Distributed under the Boost Software License, Version 1.0.
Chris@102: //  http://www.boost.org/LICENSE_1_0.txt
Chris@102: 
Chris@102: #ifndef BOOST_ENDIAN_INTRINSIC_HPP
Chris@102: #define BOOST_ENDIAN_INTRINSIC_HPP
Chris@102: 
Chris@102: //  Allow user to force BOOST_ENDIAN_NO_INTRINSICS in case they aren't available for a
Chris@102: //  particular platform/compiler combination. Please report such platform/compiler
Chris@102: //  combinations to the Boost mailing list.
Chris@102: #ifndef BOOST_ENDIAN_NO_INTRINSICS
Chris@102: 
Chris@102: #ifndef __has_builtin         // Optional of course
Chris@102:   #define __has_builtin(x) 0  // Compatibility with non-clang compilers
Chris@102: #endif
Chris@102: 
Chris@102: //  GCC and Clang recent versions provide intrinsic byte swaps via builtins
Chris@102: #if (defined(__clang__) && __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)) \
Chris@102:   || (defined(__GNUC__ ) && \
Chris@102:   (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
Chris@102: # define BOOST_ENDIAN_INTRINSIC_MSG "__builtin_bswap16, etc."
Chris@102: // prior to 4.8, gcc did not provide __builtin_bswap16 on some platforms so we emulate it
Chris@102: // see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624
Chris@102: // Clang has a similar problem, but their feature test macros make it easier to detect
Chris@102: # if (defined(__clang__) && __has_builtin(__builtin_bswap16)) \
Chris@102:   || (defined(__GNUC__) &&(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))
Chris@102: #   define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap16(x)
Chris@102: # else
Chris@102: #   define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap32((x) << 16)
Chris@102: # endif
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) __builtin_bswap32(x)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) __builtin_bswap64(x)
Chris@102: 
Chris@102: //  Linux systems provide the byteswap.h header, with 
Chris@102: #elif defined(__linux__)
Chris@102: //  don't check for obsolete forms defined(linux) and defined(__linux) on the theory that
Chris@102: //  compilers that predefine only these are so old that byteswap.h probably isn't present.
Chris@102: # define BOOST_ENDIAN_INTRINSIC_MSG "byteswap.h bswap_16, etc."
Chris@102: # include <byteswap.h>
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) bswap_16(x)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) bswap_32(x)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) bswap_64(x)
Chris@102: 
Chris@102: #elif defined(_MSC_VER)
Chris@102: //  Microsoft documents these as being compatible since Windows 95 and specificly
Chris@102: //  lists runtime library support since Visual Studio 2003 (aka 7.1).
Chris@102: # define BOOST_ENDIAN_INTRINSIC_MSG "cstdlib _byteswap_ushort, etc."
Chris@102: # include <cstdlib>
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) _byteswap_ushort(x)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) _byteswap_ulong(x)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) _byteswap_uint64(x)
Chris@102: #else
Chris@102: # define BOOST_ENDIAN_NO_INTRINSICS
Chris@102: # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
Chris@102: #endif
Chris@102: 
Chris@102: #elif !defined(BOOST_ENDIAN_INTRINSIC_MSG)
Chris@102: # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
Chris@102: #endif  // BOOST_ENDIAN_NO_INTRINSICS
Chris@102: #endif  // BOOST_ENDIAN_INTRINSIC_HPP