remove unused variable assignment, closes #14928

[wxWidgets.git] / include / wx / atomic.h

diff --git a/include/wx/atomic.h b/include/wx/atomic.h
index 83b285cf7fc54ef890503ee3777ba215e6ff1769..250ca27f19fe9b7dfcdb4904728bbb9652963977 100644 (file)
--- a/include/wx/atomic.h
+++ b/include/wx/atomic.h
@@ -25,46 +25,50 @@
 
 #if wxUSE_THREADS
 
-#if defined(__WXMSW__)
+#if defined(HAVE_GCC_ATOMIC_BUILTINS)
 
-// include standard Windows headers
-#include "wx/msw/wrapwin.h"
+// NB: we intentionally don't use Linux's asm/atomic.h header, because it's
+//     an internal kernel header that doesn't always work in userspace:
+//     http://bugs.mysql.com/bug.php?id=28456
+//     http://golubenco.org/blog/atomic-operations/
 
 inline void wxAtomicInc (wxUint32 &value)
 {
-    InterlockedIncrement ((LONG*)&value);
+    __sync_fetch_and_add(&value, 1);
 }
 
 inline wxUint32 wxAtomicDec (wxUint32 &value)
 {
-    return InterlockedDecrement ((LONG*)&value);
+    return __sync_sub_and_fetch(&value, 1);
 }
 
-#elif defined(__WXMAC__) || defined(__DARWIN__)
 
-#include "libkern/OSAtomic.h"
+#elif defined(__WINDOWS__)
+
+// include standard Windows headers
+#include "wx/msw/wrapwin.h"
+
 inline void wxAtomicInc (wxUint32 &value)
 {
-    OSAtomicIncrement32 ((int32_t*)&value);
+    InterlockedIncrement ((LONG*)&value);
 }
 
 inline wxUint32 wxAtomicDec (wxUint32 &value)
 {
-    return OSAtomicDecrement32 ((int32_t*)&value);
+    return InterlockedDecrement ((LONG*)&value);
 }
 
-#elif defined(__LINUX__)
-
-#include <asm/atomic.h>
+#elif defined(__WXMAC__) || defined(__DARWIN__)
 
+#include "libkern/OSAtomic.h"
 inline void wxAtomicInc (wxUint32 &value)
 {
-    atomic_inc ((atomic_t*)&value);
+    OSAtomicIncrement32 ((int32_t*)&value);
 }
 
 inline wxUint32 wxAtomicDec (wxUint32 &value)
 {
-    return atomic_dec_and_test ((atomic_t*)&value) ? 0 : 1;
+    return OSAtomicDecrement32 ((int32_t*)&value);
 }
 
 #elif defined (__SOLARIS__)
@@ -84,7 +88,7 @@ inline wxUint32 wxAtomicDec (wxUint32 &value)
 #else // unknown platform
 
 // it will result in inclusion if the generic implementation code a bit later in this page
-#define wxHAS_GENERIC_ATOMIC_OPS 1
+#define wxNEEDS_GENERIC_ATOMIC_OPS
 
 #endif // unknown platform
 
@@ -101,11 +105,8 @@ inline wxUint32 wxAtomicDec (wxUint32 &value) { return --value; }
 //  behaviour
 // ----------------------------------------------------------------------------
 
-#if !defined(wxHAS_GENERIC_ATOMIC_OPS)
-#define wxHAS_GENERIC_ATOMIC_OPS 0
-#endif
+#ifdef wxNEEDS_GENERIC_ATOMIC_OPS
 
-#if wxHAS_GENERIC_ATOMIC_OPS
 #include "wx/thread.h" // for wxCriticalSection
 
 class wxAtomicInt32
@@ -140,14 +141,16 @@ private:
 inline void wxAtomicInc(wxAtomicInt32 &value) { value.Inc(); }
 inline wxInt32 wxAtomicDec(wxAtomicInt32 &value) { return value.Dec(); }
 
-#else // !wxHAS_GENERIC_ATOMIC_OPS
+#else // !wxNEEDS_GENERIC_ATOMIC_OPS
+
+#define wxHAS_ATOMIC_OPS
 
 inline void wxAtomicInc(wxInt32 &value) { wxAtomicInc((wxUint32&)value); }
 inline wxInt32 wxAtomicDec(wxInt32 &value) { return wxAtomicDec((wxUint32&)value); }
 
 typedef wxInt32 wxAtomicInt32;
 
-#endif // wxHAS_GENERIC_ATOMIC_OPS
+#endif // wxNEEDS_GENERIC_ATOMIC_OPS
 
 // all the native implementations use 32 bits currently
 // for a 64 bits implementation we could use (a future) wxAtomicInt64 as