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Diffstat (limited to 'boost/endian/detail/intrinsic.hpp')
-rw-r--r-- | boost/endian/detail/intrinsic.hpp | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/boost/endian/detail/intrinsic.hpp b/boost/endian/detail/intrinsic.hpp new file mode 100644 index 0000000000..6ead6813a2 --- /dev/null +++ b/boost/endian/detail/intrinsic.hpp @@ -0,0 +1,64 @@ +// 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 |