1 /*
2 * Copyright (c) 2011 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 // Atomic system independant 32-bit signed integer.
12 // Linux implementation.
13 // Note: Requires gcc 4.1.2 or later.
14 #ifndef WEBRTC_SYSTEM_WRAPPERS_SOURCE_ATOMIC32_LINUX_H_
15 #define WEBRTC_SYSTEM_WRAPPERS_SOURCE_ATOMIC32_LINUX_H_
16
17 #include <inttypes.h>
18 #include <malloc.h>
19
20 #include "common_types.h"
21
22 namespace webrtc {
23 class Atomic32Impl
24 {
25 public:
26 inline Atomic32Impl(WebRtc_Word32 initialValue);
27 inline ~Atomic32Impl();
28
29 inline WebRtc_Word32 operator++();
30 inline WebRtc_Word32 operator--();
31
32 inline Atomic32Impl& operator=(const Atomic32Impl& rhs);
33 inline Atomic32Impl& operator=(WebRtc_Word32 rhs);
34 inline WebRtc_Word32 operator+=(WebRtc_Word32 rhs);
35 inline WebRtc_Word32 operator-=(WebRtc_Word32 rhs);
36
37 inline bool CompareExchange(WebRtc_Word32 newValue,
38 WebRtc_Word32 compareValue);
39
40 inline WebRtc_Word32 Value() const;
41 private:
42 void* _ptrMemory;
43 // Volatile ensures full memory barriers.
44 volatile WebRtc_Word32* _value;
45 };
46
47 // TODO (hellner) use aligned_malloc instead of doing it manually.
Atomic32Impl(WebRtc_Word32 initialValue)48 inline Atomic32Impl::Atomic32Impl(WebRtc_Word32 initialValue)
49 : _ptrMemory(NULL),
50 _value(NULL)
51 { // Align the memory associated with _value on a 32-bit boundary. This is a
52 // requirement for the used Linux APIs to be atomic.
53 // Keep _ptrMemory to be able to reclaim memory.
54 _ptrMemory = malloc(sizeof(WebRtc_Word32)*2);
55 _value = (WebRtc_Word32*) (((uintptr_t)_ptrMemory+3)&(~0x3));
56 *_value = initialValue;
57 }
58
~Atomic32Impl()59 inline Atomic32Impl::~Atomic32Impl()
60 {
61 if(_ptrMemory != NULL)
62 {
63 free(_ptrMemory);
64 }
65 }
66
67 inline WebRtc_Word32 Atomic32Impl::operator++()
68 {
69 WebRtc_Word32 returnValue = __sync_fetch_and_add(_value,1);
70 returnValue++;
71 return returnValue;
72 }
73
74 inline WebRtc_Word32 Atomic32Impl::operator--()
75 {
76 WebRtc_Word32 returnValue = __sync_fetch_and_sub(_value,1);
77 returnValue--;
78 return returnValue;
79 }
80
81 inline Atomic32Impl& Atomic32Impl::operator=(const Atomic32Impl& rhs)
82 {
83 *_value = *rhs._value;
84 return *this;
85 }
86
87 inline Atomic32Impl& Atomic32Impl::operator=(WebRtc_Word32 rhs)
88 {
89 *_value = rhs;
90 return *this;
91 }
92
93 inline WebRtc_Word32 Atomic32Impl::operator+=(WebRtc_Word32 rhs)
94 {
95 WebRtc_Word32 returnValue = __sync_fetch_and_add(_value,rhs);
96 returnValue += rhs;
97 return returnValue;
98 }
99
100 inline WebRtc_Word32 Atomic32Impl::operator-=(WebRtc_Word32 rhs)
101 {
102 WebRtc_Word32 returnValue = __sync_fetch_and_sub(_value,rhs);
103 returnValue -= rhs;
104 return returnValue;
105 }
106
CompareExchange(WebRtc_Word32 newValue,WebRtc_Word32 compareValue)107 inline bool Atomic32Impl::CompareExchange(WebRtc_Word32 newValue,
108 WebRtc_Word32 compareValue)
109 {
110 return __sync_bool_compare_and_swap(_value,compareValue,newValue);
111 }
112
Value()113 inline WebRtc_Word32 Atomic32Impl::Value() const
114 {
115 return *_value;
116 }
117 } // namespace webrtc
118
119 #endif // WEBRTC_SYSTEM_WRAPPERS_SOURCE_ATOMIC32_LINUX_H_
120