1 files changed, 68 insertions, 0 deletions
diff --git a/boehm-gc/include/private/darwin_semaphore.h b/boehm-gc/include/private/darwin_semaphore.h
new file mode 100644
index 000000000..0f43982d5
--- /dev/null
+++ b/boehm-gc/include/private/darwin_semaphore.h
@@ -0,0 +1,68 @@
+#ifndef GC_DARWIN_SEMAPHORE_H
+#define GC_DARWIN_SEMAPHORE_H
+
+#if !defined(GC_DARWIN_THREADS)
+#error darwin_semaphore.h included with GC_DARWIN_THREADS not defined
+#endif
+
+/*
+   This is a very simple semaphore implementation for darwin. It
+   is implemented in terms of pthreads calls so it isn't async signal
+   safe. This isn't a problem because signals aren't used to
+   suspend threads on darwin.
+*/
+   
+typedef struct {
+    pthread_mutex_t mutex;
+    pthread_cond_t cond;
+    int value;
+} sem_t;
+
+static int sem_init(sem_t *sem, int pshared, int value) {
+    int ret;
+    if(pshared)
+        GC_abort("sem_init with pshared set");
+    sem->value = value;
+    
+    ret = pthread_mutex_init(&sem->mutex,NULL);
+    if(ret < 0) return -1;
+    ret = pthread_cond_init(&sem->cond,NULL);
+    if(ret < 0) return -1;
+    return 0;
+}
+
+static int sem_post(sem_t *sem) {
+    if(pthread_mutex_lock(&sem->mutex) < 0)
+        return -1;
+    sem->value++;
+    if(pthread_cond_signal(&sem->cond) < 0) {
+        pthread_mutex_unlock(&sem->mutex);
+        return -1;
+    }
+    if(pthread_mutex_unlock(&sem->mutex) < 0)
+        return -1;
+    return 0;
+}
+
+static int sem_wait(sem_t *sem) {
+    if(pthread_mutex_lock(&sem->mutex) < 0)
+        return -1;
+    while(sem->value == 0) {
+        pthread_cond_wait(&sem->cond,&sem->mutex);
+    }
+    sem->value--;
+    if(pthread_mutex_unlock(&sem->mutex) < 0)
+        return -1;    
+    return 0;
+}
+
+static int sem_destroy(sem_t *sem) {
+    int ret;
+    ret = pthread_cond_destroy(&sem->cond);
+    if(ret < 0) return -1;
+    ret = pthread_mutex_destroy(&sem->mutex);
+    if(ret < 0) return -1;
+    return 0;
+}
+
+#endif