From a406cfaa4724b3a78683b732f016c9ad33cad187 Mon Sep 17 00:00:00 2001
From: Nikias Bassen
Date: Fri, 21 Mar 2014 20:41:56 +0100
Subject: common: add thread_once() implementation

---
 common/thread.c | 16 ++++++++++++++++
 common/thread.h |  9 +++++++++
 2 files changed, 25 insertions(+)

diff --git a/common/thread.c b/common/thread.c
index 2cf4321..d6d6c1a 100644
--- a/common/thread.c
+++ b/common/thread.c
@@ -81,3 +81,19 @@ void mutex_unlock(mutex_t* mutex)
 	pthread_mutex_unlock(mutex);
 #endif
 }
+
+void thread_once(thread_once_t *once_control, void (*init_routine)(void))
+{
+#ifdef WIN32
+	while (InterlockedExchange(&(once_control->lock), 1) != 0) {
+		Sleep(1);
+	}
+	if (!once_control->state) {
+		once_control->state = 1;
+		init_routine();
+	}
+	InterlockedExchange(&(once_control->lock), 0);
+#else
+	pthread_once(once_control, init_routine);
+#endif	
+}
diff --git a/common/thread.h b/common/thread.h
index e74ee74..5d20083 100644
--- a/common/thread.h
+++ b/common/thread.h
@@ -26,10 +26,17 @@
 #include <windows.h>
 typedef HANDLE thread_t;
 typedef CRITICAL_SECTION mutex_t;
+typedef volatile struct {
+	LONG lock;
+	int state;
+} thread_once_t;
+#define THREAD_ONCE_INIT {0, 0}
 #else
 #include <pthread.h>
 typedef pthread_t thread_t;
 typedef pthread_mutex_t mutex_t;
+typedef pthread_once_t thread_once_t;
+#define THREAD_ONCE_INIT PTHREAD_ONCE_INIT
 #endif
 
 typedef void* (*thread_func_t)(void* data);
@@ -42,4 +49,6 @@ void mutex_destroy(mutex_t* mutex);
 void mutex_lock(mutex_t* mutex);
 void mutex_unlock(mutex_t* mutex);
 
+void thread_once(thread_once_t *once_control, void (*init_routine)(void));
+
 #endif
-- 
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