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 
18 namespace webrtc {
19 
Atomic32(int32_t initial_value)20 Atomic32::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 
~Atomic32()27 Atomic32::~Atomic32() {
28 }
29 
operator ++()30 int32_t Atomic32::operator++() {
31   return static_cast<int32_t>(InterlockedIncrement(
32       reinterpret_cast<volatile LONG*>(&value_)));
33 }
34 
operator --()35 int32_t Atomic32::operator--() {
36   return static_cast<int32_t>(InterlockedDecrement(
37       reinterpret_cast<volatile LONG*>(&value_)));
38 }
39 
operator +=(int32_t value)40 int32_t Atomic32::operator+=(int32_t value) {
41   return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
42                                 value);
43 }
44 
operator -=(int32_t value)45 int32_t Atomic32::operator-=(int32_t value) {
46   return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
47                                 -value);
48 }
49 
CompareExchange(int32_t new_value,int32_t compare_value)50 bool 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