1/*
2 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include "webrtc/system_wrappers/include/atomic32.h"
12
13#include <assert.h>
14#include <windows.h>
15
16#include "webrtc/common_types.h"
17
18namespace webrtc {
19
20Atomic32::Atomic32(int32_t initial_value)
21    : value_(initial_value) {
22  static_assert(sizeof(value_) == sizeof(LONG),
23                "counter variable is the expected size");
24  assert(Is32bitAligned());
25}
26
27Atomic32::~Atomic32() {
28}
29
30int32_t Atomic32::operator++() {
31  return static_cast<int32_t>(InterlockedIncrement(
32      reinterpret_cast<volatile LONG*>(&value_)));
33}
34
35int32_t Atomic32::operator--() {
36  return static_cast<int32_t>(InterlockedDecrement(
37      reinterpret_cast<volatile LONG*>(&value_)));
38}
39
40int32_t Atomic32::operator+=(int32_t value) {
41  return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
42                                value);
43}
44
45int32_t Atomic32::operator-=(int32_t value) {
46  return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
47                                -value);
48}
49
50bool Atomic32::CompareExchange(int32_t new_value, int32_t compare_value) {
51  const LONG old_value = InterlockedCompareExchange(
52      reinterpret_cast<volatile LONG*>(&value_),
53      new_value,
54      compare_value);
55
56  // If the old value and the compare value is the same an exchange happened.
57  return (old_value == compare_value);
58}
59
60}  // namespace webrtc
61