import RT-Thread@9217865c without bsp, libcpu and components/net

examples/utest/testcases/mm/semaphore.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-03-24     WangXiaoyao  Complete testcase for synchronization
+ */
+#ifndef __SEMAPHORE_H__
+#define __SEMAPHORE_H__
+
+#include <stdatomic.h>
+
+typedef struct {
+    atomic_int count;
+} semaphore_t;
+
+void semaphore_init(semaphore_t *sem, int count)
+{
+    atomic_init(&sem->count, count);
+}
+
+void semaphore_wait(semaphore_t *sem)
+{
+    int count;
+    do {
+        count = atomic_load(&sem->count);
+    } while (count == 0 || !atomic_compare_exchange_weak(&sem->count, &count, count - 1));
+}
+
+void semaphore_signal(semaphore_t *sem)
+{
+    atomic_fetch_add(&sem->count, 1);
+}
+
+#endif /* __SEMAPHORE_H__ */