ceph/src/boost/libs/endian/include/boost/endian/detail/intrinsic.hpp

   1 //  endian/detail/intrinsic.hpp  -------------------------------------------------------//
   2
   3 //  Copyright (C) 2012 David Stone
   4 //  Copyright Beman Dawes 2013
   5
   6 //  Distributed under the Boost Software License, Version 1.0.
   7 //  http://www.boost.org/LICENSE_1_0.txt
   8
   9 #ifndef BOOST_ENDIAN_INTRINSIC_HPP
  10 #define BOOST_ENDIAN_INTRINSIC_HPP
  11
  12 //  Allow user to force BOOST_ENDIAN_NO_INTRINSICS in case they aren't available for a
  13 //  particular platform/compiler combination. Please report such platform/compiler
  14 //  combinations to the Boost mailing list.
  15 #ifndef BOOST_ENDIAN_NO_INTRINSICS
  16
  17 #ifndef __has_builtin         // Optional of course
  18   #define __has_builtin(x) 0  // Compatibility with non-clang compilers
  19 #endif
  20
  21 #if defined(_MSC_VER)
  22 //  Microsoft documents these as being compatible since Windows 95 and specifically
  23 //  lists runtime library support since Visual Studio 2003 (aka 7.1).
  24 //  Clang/c2 uses the Microsoft rather than GCC intrinsics, so we check for
  25 //  defined(_MSC_VER) before defined(__clang__)
  26 # define BOOST_ENDIAN_INTRINSIC_MSG "cstdlib _byteswap_ushort, etc."
  27 # include <cstdlib>
  28 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) _byteswap_ushort(x)
  29 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) _byteswap_ulong(x)
  30 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) _byteswap_uint64(x)
  31
  32 //  GCC and Clang recent versions provide intrinsic byte swaps via builtins
  33 #elif (defined(__clang__) && __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)) \
  34   || (defined(__GNUC__ ) && \
  35   (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
  36 # define BOOST_ENDIAN_INTRINSIC_MSG "__builtin_bswap16, etc."
  37 // prior to 4.8, gcc did not provide __builtin_bswap16 on some platforms so we emulate it
  38 // see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624
  39 // Clang has a similar problem, but their feature test macros make it easier to detect
  40 # if (defined(__clang__) && __has_builtin(__builtin_bswap16)) \
  41   || (defined(__GNUC__) &&(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))
  42 #   define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap16(x)
  43 # else
  44 #   define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) __builtin_bswap32((x) << 16)
  45 # endif
  46 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) __builtin_bswap32(x)
  47 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) __builtin_bswap64(x)
  48
  49 //  Linux systems provide the byteswap.h header, with
  50 #elif defined(__linux__)
  51 //  don't check for obsolete forms defined(linux) and defined(__linux) on the theory that
  52 //  compilers that predefine only these are so old that byteswap.h probably isn't present.
  53 # define BOOST_ENDIAN_INTRINSIC_MSG "byteswap.h bswap_16, etc."
  54 # include <byteswap.h>
  55 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_2(x) bswap_16(x)
  56 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_4(x) bswap_32(x)
  57 # define BOOST_ENDIAN_INTRINSIC_BYTE_SWAP_8(x) bswap_64(x)
  58
  59 #else
  60 # define BOOST_ENDIAN_NO_INTRINSICS
  61 # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
  62 #endif
  63
  64 #elif !defined(BOOST_ENDIAN_INTRINSIC_MSG)
  65 # define BOOST_ENDIAN_INTRINSIC_MSG "no byte swap intrinsics"
  66 #endif  // BOOST_ENDIAN_NO_INTRINSICS
  67 #endif  // BOOST_ENDIAN_INTRINSIC_HPP