Add semaphore based signal implementation

include/sta/os2/signal.hpp

@@ -0,0 +1,27 @@
+#ifndef STA_OS2_SIGNAL_HPP
+#define STA_OS2_SIGNAL_HPP
+
+#include <sta/signal.hpp>
+
+#include <cmsis_os2.h>
+
+
+namespace sta
+{
+	class Os2Signal : public Signal
+	{
+	public:
+		Os2Signal(osSemaphoreId_t * semaphore);
+
+		void notify() override;
+		bool peek() override;
+		bool test() override;
+		void wait() override;
+
+	private:
+		osSemaphoreId_t * semaphore_;
+	};
+} // namespace sta
+
+
+#endif // STA_OS2_SIGNAL_HPP

src/os2/signal.cpp

@@ -0,0 +1,29 @@
+#include <sta/os2/signal.hpp>
+
+
+namespace sta
+{
+	Os2Signal::Os2Signal(osSemaphoreId_t * semaphore)
+		: semaphore_{semaphore}
+	{}
+
+	void Os2Signal::notify()
+	{
+		osSemaphoreRelease(*semaphore_);
+	}
+
+	bool Os2Signal::peek()
+	{
+		return (osSemaphoreGetCount(*semaphore_) != 0);
+	}
+
+	bool Os2Signal::test()
+	{
+		return (osSemaphoreAcquire(*semaphore_, 0) == osOK);
+	}
+
+	void Os2Signal::wait()
+	{
+		osSemaphoreAcquire(*semaphore_, osWaitForever);
+	}
+} // namespace sta