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      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/interface/atomic32.h"
     12 
     13 #include <assert.h>
     14 #include <windows.h>
     15 
     16 #include "webrtc/common_types.h"
     17 #include "webrtc/system_wrappers/interface/compile_assert.h"
     18 
     19 namespace webrtc {
     20 
     21 Atomic32::Atomic32(int32_t initial_value)
     22     : value_(initial_value) {
     23   COMPILE_ASSERT(sizeof(value_) == sizeof(LONG),
     24                  counter_variable_is_the_expected_size);
     25   assert(Is32bitAligned());
     26 }
     27 
     28 Atomic32::~Atomic32() {
     29 }
     30 
     31 int32_t Atomic32::operator++() {
     32   return static_cast<int32_t>(InterlockedIncrement(
     33       reinterpret_cast<volatile LONG*>(&value_)));
     34 }
     35 
     36 int32_t Atomic32::operator--() {
     37   return static_cast<int32_t>(InterlockedDecrement(
     38       reinterpret_cast<volatile LONG*>(&value_)));
     39 }
     40 
     41 int32_t Atomic32::operator+=(int32_t value) {
     42   return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
     43                                 value);
     44 }
     45 
     46 int32_t Atomic32::operator-=(int32_t value) {
     47   return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&value_),
     48                                 -value);
     49 }
     50 
     51 bool Atomic32::CompareExchange(int32_t new_value, int32_t compare_value) {
     52   const LONG old_value = InterlockedCompareExchange(
     53       reinterpret_cast<volatile LONG*>(&value_),
     54       new_value,
     55       compare_value);
     56 
     57   // If the old value and the compare value is the same an exchange happened.
     58   return (old_value == compare_value);
     59 }
     60 
     61 }  // namespace webrtc
     62