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//
// detail/gcc_x86_fenced_block.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef ASIO_DETAIL_GCC_X86_FENCED_BLOCK_HPP
#define ASIO_DETAIL_GCC_X86_FENCED_BLOCK_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
#include "asio/detail/noncopyable.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
class gcc_x86_fenced_block
: private noncopyable
{
public:
enum half_t { half };
enum full_t { full };
// Constructor for a half fenced block.
explicit gcc_x86_fenced_block(half_t)
{
}
// Constructor for a full fenced block.
explicit gcc_x86_fenced_block(full_t)
{
lbarrier();
}
// Destructor.
~gcc_x86_fenced_block()
{
sbarrier();
}
private:
static int barrier()
{
int r = 0, m = 1;
__asm__ __volatile__ (
"xchgl %0, %1" :
"=r"(r), "=m"(m) :
"0"(1), "m"(m) :
"memory", "cc");
return r;
}
static void lbarrier()
{
#if defined(__SSE2__)
# if (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
__builtin_ia32_lfence();
# else // (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
__asm__ __volatile__ ("lfence" ::: "memory");
# endif // (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
#else // defined(__SSE2__)
barrier();
#endif // defined(__SSE2__)
}
static void sbarrier()
{
#if defined(__SSE2__)
# if (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
__builtin_ia32_sfence();
# else // (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
__asm__ __volatile__ ("sfence" ::: "memory");
# endif // (__GNUC__ >= 4) && !defined(__INTEL_COMPILER) && !defined(__ICL)
#else // defined(__SSE2__)
barrier();
#endif // defined(__SSE2__)
}
};
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
#endif // ASIO_DETAIL_GCC_X86_FENCED_BLOCK_HPP
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