base/atomicops_internals_x86_msvc.h

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file is an internal atomic implementation, use base/atomicops.h instead.

#ifndef BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_
#define BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_

#include "base/win/windows_types.h"

#include <intrin.h>

#include "base/macros.h"
#include "build/build_config.h"

#if defined(ARCH_CPU_64_BITS)
// windows.h #defines this (only on x64). This causes problems because the
// public API also uses MemoryBarrier at the public name for this fence. So, on
// X64, undef it, and call its documented
// (http://msdn.microsoft.com/en-us/library/windows/desktop/ms684208.aspx)
// implementation directly.
#undef MemoryBarrier
#endif

namespace base {
namespace subtle {

inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
                                         Atomic32 old_value,
                                         Atomic32 new_value) {
  LONG result = _InterlockedCompareExchange(
      reinterpret_cast<volatile LONG*>(ptr),
      static_cast<LONG>(new_value),
      static_cast<LONG>(old_value));
  return static_cast<Atomic32>(result);
}

inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
                                         Atomic32 new_value) {
  LONG result = _InterlockedExchange(
      reinterpret_cast<volatile LONG*>(ptr),
      static_cast<LONG>(new_value));
  return static_cast<Atomic32>(result);
}

inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
                                        Atomic32 increment) {
  return _InterlockedExchangeAdd(
      reinterpret_cast<volatile LONG*>(ptr),
      static_cast<LONG>(increment)) + increment;
}

inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
                                          Atomic32 increment) {
  return Barrier_AtomicIncrement(ptr, increment);
}

inline void MemoryBarrier() {
#if defined(ARCH_CPU_64_BITS)
  // See #undef and note at the top of this file.
  __faststorefence();
#else
  // We use the implementation of MemoryBarrier from WinNT.h
  LONG barrier;

  _InterlockedOr(&barrier, 0);
#endif
}

inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                       Atomic32 old_value,
                                       Atomic32 new_value) {
  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
}

inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                       Atomic32 old_value,
                                       Atomic32 new_value) {
  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
}

inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
  *ptr = value;
}

inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
  NoBarrier_AtomicExchange(ptr, value);
              // acts as a barrier in this implementation
}

inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
  *ptr = value; // works w/o barrier for current Intel chips as of June 2005
  // See comments in Atomic64 version of Release_Store() below.
}

inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
  return *ptr;
}

inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
  Atomic32 value = *ptr;
  return value;
}

inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
  MemoryBarrier();
  return *ptr;
}

#if defined(_WIN64)

// 64-bit low-level operations on 64-bit platform.

static_assert(sizeof(Atomic64) == sizeof(PVOID), "atomic word is atomic");

inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
                                         Atomic64 old_value,
                                         Atomic64 new_value) {
  PVOID result = _InterlockedCompareExchangePointer(
      reinterpret_cast<volatile PVOID*>(ptr),
      reinterpret_cast<PVOID>(new_value), reinterpret_cast<PVOID>(old_value));
  return reinterpret_cast<Atomic64>(result);
}

inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
                                         Atomic64 new_value) {
  PVOID result =
      _InterlockedExchangePointer(reinterpret_cast<volatile PVOID*>(ptr),
                                  reinterpret_cast<PVOID>(new_value));
  return reinterpret_cast<Atomic64>(result);
}

inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
                                        Atomic64 increment) {
  return _InterlockedExchangeAdd64(reinterpret_cast<volatile LONGLONG*>(ptr),
                                   static_cast<LONGLONG>(increment)) +
         increment;
}

inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
                                          Atomic64 increment) {
  return Barrier_AtomicIncrement(ptr, increment);
}

inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
  *ptr = value;
}

inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
  NoBarrier_AtomicExchange(ptr, value);
              // acts as a barrier in this implementation
}

inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
  *ptr = value; // works w/o barrier for current Intel chips as of June 2005

  // When new chips come out, check:
  //  IA-32 Intel Architecture Software Developer's Manual, Volume 3:
  //  System Programming Guide, Chatper 7: Multiple-processor management,
  //  Section 7.2, Memory Ordering.
  // Last seen at:
  //   http://developer.intel.com/design/pentium4/manuals/index_new.htm
}

inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
  return *ptr;
}

inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
  Atomic64 value = *ptr;
  return value;
}

inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
  MemoryBarrier();
  return *ptr;
}

inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
                                       Atomic64 old_value,
                                       Atomic64 new_value) {
  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
}

inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
                                       Atomic64 old_value,
                                       Atomic64 new_value) {
  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
}


#endif  // defined(_WIN64)

}  // namespace subtle
}  // namespace base

#endif  // BASE_ATOMICOPS_INTERNALS_X86_MSVC_H_