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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 "atomic32.h"
     12 
     13 #include <assert.h>
     14 #include <windows.h>
     15 
     16 #include "common_types.h"
     17 #include "compile_assert.h"
     18 
     19 namespace webrtc {
     20 
     21 Atomic32::Atomic32(WebRtc_Word32 initialValue) : _value(initialValue)
     22 {
     23     // Make sure that the counter variable we're using is of the same size
     24     // as what the API expects.
     25     COMPILE_ASSERT(sizeof(_value) == sizeof(LONG));
     26     assert(Is32bitAligned());
     27 }
     28 
     29 Atomic32::~Atomic32()
     30 {
     31 }
     32 
     33 WebRtc_Word32 Atomic32::operator++()
     34 {
     35     return static_cast<WebRtc_Word32>(InterlockedIncrement(
     36         reinterpret_cast<volatile LONG*>(&_value)));
     37 }
     38 
     39 WebRtc_Word32 Atomic32::operator--()
     40 {
     41     return static_cast<WebRtc_Word32>(InterlockedDecrement(
     42         reinterpret_cast<volatile LONG*>(&_value)));
     43 }
     44 
     45 WebRtc_Word32 Atomic32::operator+=(WebRtc_Word32 value)
     46 {
     47     return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&_value),
     48                                   value);
     49 }
     50 
     51 WebRtc_Word32 Atomic32::operator-=(WebRtc_Word32 value)
     52 {
     53     return InterlockedExchangeAdd(reinterpret_cast<volatile LONG*>(&_value),
     54                                   -value);
     55 }
     56 
     57 bool Atomic32::CompareExchange(WebRtc_Word32 newValue,
     58                                WebRtc_Word32 compareValue)
     59 {
     60     const LONG oldValue = InterlockedCompareExchange(
     61           reinterpret_cast<volatile LONG*>(&_value),
     62           newValue,
     63           compareValue);
     64     // If the old value and the compare value is the same an exchange happened.
     65     return (oldValue == compareValue);
     66 }
     67 
     68 WebRtc_Word32 Atomic32::Value() const
     69 {
     70     return _value;
     71 }
     72 }  // namespace webrtc
     73