68 lines
3.1 KiB
C++
68 lines
3.1 KiB
C++
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// endian/detail/intrinsic.hpp -------------------------------------------------------//
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// Copyright (C) 2012 David Stone
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// Copyright Beman Dawes 2013
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// Distributed under the Boost Software License, Version 1.0.
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// http://www.boost.org/LICENSE_1_0.txt
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#ifndef BOOST_ENDIAN_INTRINSIC_HPP
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#define BOOST_ENDIAN_INTRINSIC_HPP
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// Allow user to force BOOST_ENDIAN_NO_INTRINSICS in case they aren't available for a
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// particular platform/compiler combination. Please report such platform/compiler
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// combinations to the Boost mailing list.
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#ifndef BOOST_ENDIAN_NO_INTRINSICS
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#ifndef __has_builtin // Optional of course
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#define __has_builtin(x) 0 // Compatibility with non-clang compilers
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#endif
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#if defined(_MSC_VER)
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// Microsoft documents these as being compatible since Windows 95 and specifically
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// lists runtime library support since Visual Studio 2003 (aka 7.1).
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// Clang/c2 uses the Microsoft rather than GCC intrinsics, so we check for
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// defined(_MSC_VER) before defined(__clang__)
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# define BOOST_ENDIAN_INTRINSIC_MSG "cstdlib _byteswap_ushort, etc."
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# include <cstdlib>
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) _byteswap_ushort(x)
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) _byteswap_ulong(x)
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) _byteswap_uint64(x)
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// GCC and Clang recent versions provide intrinsic byte swaps via builtins
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#elif (defined(__clang__) && __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)) \
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|| (defined(__GNUC__ ) && \
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(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
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# define BOOST_ENDIAN_INTRINSIC_MSG "__builtin_bswap16, etc."
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// prior to 4.8, gcc did not provide __builtin_bswap16 on some platforms so we emulate it
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// see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624
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// Clang has a similar problem, but their feature test macros make it easier to detect
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# if (defined(__clang__) && __has_builtin(__builtin_bswap16)) \
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|| (defined(__GNUC__) &&(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap16(x)
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# else
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap32((x) << 16)
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# endif
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) __builtin_bswap32(x)
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) __builtin_bswap64(x)
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// Linux systems provide the byteswap.h header, with
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#elif defined(__linux__)
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// don't check for obsolete forms defined(linux) and defined(__linux) on the theory that
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// compilers that predefine only these are so old that byteswap.h probably isn't present.
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# define BOOST_ENDIAN_INTRINSIC_MSG "byteswap.h bswap_16, etc."
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# include <byteswap.h>
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) bswap_16(x)
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) bswap_32(x)
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# define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) bswap_64(x)
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#else
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# define BOOST_ENDIAN_NO_INTRINSICS
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# define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
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#endif
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#elif !defined(BOOST_ENDIAN_INTRINSIC_MSG)
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# define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
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#endif // BOOST_ENDIAN_NO_INTRINSICS
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#endif // BOOST_ENDIAN_INTRINSIC_HPP
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