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+// 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