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1 /////////////////////////////////////////////////////////////////////////////
2 // Name: wx/atomic.h
3 // Purpose: functions to manipulate atomically integers and pointers
4 // Author: Armel Asselin
5 // Created: 12/13/2006
6 // RCS-ID: $Id$
7 // Copyright: (c) Armel Asselin
8 // Licence: wxWindows licence
9 /////////////////////////////////////////////////////////////////////////////
10
11 #ifndef _WX_ATOMIC_H_
12 #define _WX_ATOMIC_H_
13
14 // ----------------------------------------------------------------------------
15 // headers
16 // ----------------------------------------------------------------------------
17
18 // get the value of wxUSE_THREADS configuration flag
19 #include "wx/defs.h"
20
21 // constraints on the various functions:
22 // - wxAtomicDec must return a zero value if the value is zero once
23 // decremented else it must return any non-zero value (the true value is OK
24 // but not necessary).
25
26 #if wxUSE_THREADS
27
28 #if defined(HAVE_GCC_ATOMIC_BUILTINS)
29
30 // NB: we intentionally don't use Linux's asm/atomic.h header, because it's
31 // an internal kernel header that doesn't always work in userspace:
32 // http://bugs.mysql.com/bug.php?id=28456
33 // http://golubenco.org/blog/atomic-operations/
34
35 inline void wxAtomicInc (wxUint32 &value)
36 {
37 __sync_fetch_and_add(&value, 1);
38 }
39
40 inline wxUint32 wxAtomicDec (wxUint32 &value)
41 {
42 return __sync_sub_and_fetch(&value, 1);
43 }
44
45
46 #elif defined(__WXMSW__)
47
48 // include standard Windows headers
49 #include "wx/msw/wrapwin.h"
50
51 inline void wxAtomicInc (wxUint32 &value)
52 {
53 InterlockedIncrement ((LONG*)&value);
54 }
55
56 inline wxUint32 wxAtomicDec (wxUint32 &value)
57 {
58 return InterlockedDecrement ((LONG*)&value);
59 }
60
61 #elif defined(__WXMAC__) || defined(__DARWIN__)
62
63 #include "libkern/OSAtomic.h"
64 inline void wxAtomicInc (wxUint32 &value)
65 {
66 OSAtomicIncrement32 ((int32_t*)&value);
67 }
68
69 inline wxUint32 wxAtomicDec (wxUint32 &value)
70 {
71 return OSAtomicDecrement32 ((int32_t*)&value);
72 }
73
74 #elif defined (__SOLARIS__)
75
76 #include <atomic.h>
77
78 inline void wxAtomicInc (wxUint32 &value)
79 {
80 atomic_add_32 ((uint32_t*)&value, 1);
81 }
82
83 inline wxUint32 wxAtomicDec (wxUint32 &value)
84 {
85 return atomic_add_32_nv ((uint32_t*)&value, (uint32_t)-1);
86 }
87
88 #else // unknown platform
89
90 // it will result in inclusion if the generic implementation code a bit later in this page
91 #define wxHAS_GENERIC_ATOMIC_OPS 1
92
93 #endif // unknown platform
94
95 #else // else of wxUSE_THREADS
96 // if no threads are used we can safely use simple ++/--
97
98 inline void wxAtomicInc (wxUint32 &value) { ++value; }
99 inline wxUint32 wxAtomicDec (wxUint32 &value) { return --value; }
100
101 #endif // !wxUSE_THREADS
102
103 // ----------------------------------------------------------------------------
104 // proxies to actual implementations, but for various other types with same
105 // behaviour
106 // ----------------------------------------------------------------------------
107
108 #if !defined(wxHAS_GENERIC_ATOMIC_OPS)
109 #define wxHAS_GENERIC_ATOMIC_OPS 0
110 #endif
111
112 #if wxHAS_GENERIC_ATOMIC_OPS
113 #include "wx/thread.h" // for wxCriticalSection
114
115 class wxAtomicInt32
116 {
117 public:
118 wxAtomicInt32() { } // non initialized for consistency with basic int type
119 wxAtomicInt32(wxInt32 v) : m_value(v) { }
120 wxAtomicInt32(const wxAtomicInt32& a) : m_value(a.m_value) {}
121
122 operator wxInt32() const { return m_value; }
123 operator volatile wxInt32&() { return m_value; }
124
125 wxAtomicInt32& operator=(wxInt32 v) { m_value = v; return *this; }
126
127 void Inc()
128 {
129 wxCriticalSectionLocker lock(m_locker);
130 ++m_value;
131 }
132
133 wxInt32 Dec()
134 {
135 wxCriticalSectionLocker lock(m_locker);
136 return --m_value;
137 }
138
139 private:
140 volatile wxInt32 m_value;
141 wxCriticalSection m_locker;
142 };
143
144 inline void wxAtomicInc(wxAtomicInt32 &value) { value.Inc(); }
145 inline wxInt32 wxAtomicDec(wxAtomicInt32 &value) { return value.Dec(); }
146
147 #else // !wxHAS_GENERIC_ATOMIC_OPS
148
149 inline void wxAtomicInc(wxInt32 &value) { wxAtomicInc((wxUint32&)value); }
150 inline wxInt32 wxAtomicDec(wxInt32 &value) { return wxAtomicDec((wxUint32&)value); }
151
152 typedef wxInt32 wxAtomicInt32;
153
154 #endif // wxHAS_GENERIC_ATOMIC_OPS
155
156 // all the native implementations use 32 bits currently
157 // for a 64 bits implementation we could use (a future) wxAtomicInt64 as
158 // default type
159 typedef wxAtomicInt32 wxAtomicInt;
160
161 #endif // _WX_ATOMIC_H_