Merge pull request #5 from WinampDesktop/community

Merge to main

1 files changed, 43 insertions, 0 deletions

diff --git a/Src/replicant/nx/win/nxonce.c b/Src/replicant/nx/win/nxonce.c
new file mode 100644
index 00000000..293534f7
--- /dev/null
+++ b/Src/replicant/nx/win/nxonce.c
@@ -0,0 +1,43 @@
+#include "nxonce.h"
+#include "foundation/error.h"
+#if 0 && _WIN32_WINNT >= 0x600
+
+void NXOnce(nx_once_t once, int (NX_ONCE_API *init_fn)(nx_once_t, void *, void **), void *param)
+{
+	InitOnceExecuteOnce(once, (PINIT_ONCE_FN)init_fn, param, 0);
+}
+
+void NXOnceInit(nx_once_t once)
+{
+	InitOnceInitialize(once);
+}
+#else
+/* this ONLY works because of the strict(ish) memory ordering of the AMD64/x86 processors. 
+ Don't use this implementation for a processor that has loose memory ordering restriction (e.g. ARM, PowerPC)
+ see http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf
+ */
+void NXOnce(nx_once_t once, int (NX_ONCE_API *init_fn)(nx_once_t, void *, void **), void *param)
+{
+    if (once->status)
+        return;
+    
+    EnterCriticalSection(&once->critical_section);
+    if (once->status)
+    {
+        LeaveCriticalSection(&once->critical_section);
+        return;
+    }
+    
+    init_fn(once, param, 0);
+    // benski> not important for the x86, but on processors with weak memory-order on stores, once->status might set to 1 BEFORE all stores from init_fn complete!
+    once->status = 1;
+    LeaveCriticalSection(&once->critical_section);
+}
+
+void NXOnceInit(nx_once_t once)
+{
+	once->status=0;
+	InitializeCriticalSection(&once->critical_section);	
+}
+
+#endif
\ No newline at end of file