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Filename : interlocked_read.hpp
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#ifndef BOOST_THREAD_DETAIL_INTERLOCKED_READ_WIN32_HPP
#define BOOST_THREAD_DETAIL_INTERLOCKED_READ_WIN32_HPP

//  interlocked_read_win32.hpp
//
//  (C) Copyright 2005-8 Anthony Williams
//  (C) Copyright 2012 Vicente J. Botet Escriba
//  (C) Copyright 2017 Andrey Semashev
//
//  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)

#include <boost/detail/interlocked.hpp>
#include <boost/thread/detail/config.hpp>

#include <boost/config/abi_prefix.hpp>

// Define compiler barriers
#if defined(__INTEL_COMPILER)
#define BOOST_THREAD_DETAIL_COMPILER_BARRIER() __memory_barrier()
#elif defined(__clang__)
#define BOOST_THREAD_DETAIL_COMPILER_BARRIER() __atomic_signal_fence(__ATOMIC_SEQ_CST)
#elif defined(_MSC_VER) && !defined(_WIN32_WCE)
extern "C" void _ReadWriteBarrier(void);
#pragma intrinsic(_ReadWriteBarrier)
#define BOOST_THREAD_DETAIL_COMPILER_BARRIER() _ReadWriteBarrier()
#endif

#ifndef BOOST_THREAD_DETAIL_COMPILER_BARRIER
#define BOOST_THREAD_DETAIL_COMPILER_BARRIER()
#endif

#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))

// Since VS2005 and until VS2012 volatile reads always acquire and volatile writes are always release.
// But VS2012 adds a compiler switch that can change behavior to the standard. On x86 though
// the compiler generates a single instruction for the load/store, which is enough synchronization
// as far as uarch is concerned. To prevent compiler reordering code around the load/store we add
// compiler barriers.

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            long const res=*x;
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            return res;
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            void* const res=*x;
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            return res;
        }

        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            *x=value;
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            *x=value;
        }
    }
}

#elif defined(_MSC_VER) && _MSC_VER >= 1700 && (defined(_M_ARM) || defined(_M_ARM64))

#include <intrin.h>

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            long const res=__iso_volatile_load32((const volatile __int32*)x);
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            __dmb(0xB); // _ARM_BARRIER_ISH, see armintr.h from MSVC 11 and later
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            return res;
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            void* const res=
#if defined(_M_ARM64)
                (void*)__iso_volatile_load64((const volatile __int64*)x);
#else
                (void*)__iso_volatile_load32((const volatile __int32*)x);
#endif
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            __dmb(0xB); // _ARM_BARRIER_ISH, see armintr.h from MSVC 11 and later
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            return res;
        }

        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            __dmb(0xB); // _ARM_BARRIER_ISH, see armintr.h from MSVC 11 and later
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            __iso_volatile_store32((volatile __int32*)x, (__int32)value);
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
            __dmb(0xB); // _ARM_BARRIER_ISH, see armintr.h from MSVC 11 and later
            BOOST_THREAD_DETAIL_COMPILER_BARRIER();
#if defined(_M_ARM64)
            __iso_volatile_store64((volatile __int64*)x, (__int64)value);
#else
            __iso_volatile_store32((volatile __int32*)x, (__int32)value);
#endif
        }
    }
}

#elif defined(__GNUC__) && (((__GNUC__ * 100 + __GNUC_MINOR__) >= 407) || (defined(__clang__) && (__clang_major__ * 100 + __clang_minor__) >= 302))

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            return __atomic_load_n((long*)x, __ATOMIC_ACQUIRE);
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            return __atomic_load_n((void**)x, __ATOMIC_ACQUIRE);
        }

        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            __atomic_store_n((long*)x, value, __ATOMIC_RELEASE);
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            __atomic_store_n((void**)x, value, __ATOMIC_RELEASE);
        }
    }
}

#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            long res;
            __asm__ __volatile__ ("movl %1, %0" : "=r" (res) : "m" (*x) : "memory");
            return res;
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            void* res;
#if defined(__x86_64__)
            __asm__ __volatile__ ("movq %1, %0" : "=r" (res) : "m" (*x) : "memory");
#else
            __asm__ __volatile__ ("movl %1, %0" : "=r" (res) : "m" (*x) : "memory");
#endif
            return res;
        }

        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            __asm__ __volatile__ ("movl %1, %0" : "=m" (*x) : "r" (value) : "memory");
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
#if defined(__x86_64__)
            __asm__ __volatile__ ("movq %1, %0" : "=m" (*x) : "r" (value) : "memory");
#else
            __asm__ __volatile__ ("movl %1, %0" : "=m" (*x) : "r" (value) : "memory");
#endif
        }
    }
}

#else

namespace boost
{
    namespace detail
    {
        inline long interlocked_read_acquire(long volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE((long*)x,0,0);
        }
        inline void* interlocked_read_acquire(void* volatile* x) BOOST_NOEXCEPT
        {
            return BOOST_INTERLOCKED_COMPARE_EXCHANGE_POINTER((void**)x,0,0);
        }
        inline void interlocked_write_release(long volatile* x,long value) BOOST_NOEXCEPT
        {
            BOOST_INTERLOCKED_EXCHANGE((long*)x,value);
        }
        inline void interlocked_write_release(void* volatile* x,void* value) BOOST_NOEXCEPT
        {
            BOOST_INTERLOCKED_EXCHANGE_POINTER((void**)x,value);
        }
    }
}

#endif

#include <boost/config/abi_suffix.hpp>

#endif