[C++] Add C++ interface for RT-Thread kernel.

components/cplusplus/Semaphore.cpp

@@ -0,0 +1,30 @@
+#include "Semaphore.h"
+
+using namespace rtthread;
+
+Semaphore::Semaphore(const char *name, int32_t count)
+{
+    rt_sem_init(&mID, name, count, RT_IPC_FLAG_FIFO);
+}
+
+bool Semaphore::wait(int32_t millisec)
+{
+    rt_int32_t tick;
+
+    if (millisec < 0)
+        tick = -1;
+    else
+        tick = rt_tick_from_millisecond(millisec);
+
+    return rt_sem_take(&mID, tick) == RT_EOK;
+}
+
+void Semaphore::release(void)
+{
+    rt_sem_release(&mID);
+}
+
+Semaphore::~Semaphore()
+{
+    rt_sem_detach(&mID);
+}