+/**
+ * Initializes a semaphore.
+ */
+void vlc_sem_init (vlc_sem_t *sem, unsigned value)
+{
+ if (sem_init (sem, 0, value))
+ abort ();
+}
+
+/**
+ * Destroys a semaphore.
+ */
+void vlc_sem_destroy (vlc_sem_t *sem)
+{
+ int val = sem_destroy (sem);
+ VLC_THREAD_ASSERT ("destroying semaphore");
+}
+
+/**
+ * Increments the value of a semaphore.
+ */
+int vlc_sem_post (vlc_sem_t *sem)
+{
+ int val = sem_post (sem);
+ if (val != EOVERFLOW)
+ VLC_THREAD_ASSERT ("unlocking semaphore");
+ return val;
+}
+
+/**
+ * Atomically wait for the semaphore to become non-zero (if needed),
+ * then decrements it.
+ */
+void vlc_sem_wait (vlc_sem_t *sem)
+{
+ int val;
+ do
+ val = sem_wait (sem);
+ while (val == EINTR);
+ VLC_THREAD_ASSERT ("locking semaphore");
+}
+