added stdc++ coroutine example

Author: rajszym

stdc++/coroutine.cpp

@@ -0,0 +1,45 @@
+#include "stm32f4_discovery.h"
+#include <thread>
+#include <coroutine>
+
+struct Generator
+{
+	struct promise_type
+	{
+		int current_value;
+
+		Generator get_return_object() { return Generator{std::coroutine_handle<promise_type>::from_promise(*this)}; }
+
+		std::suspend_always initial_suspend() { return {}; }
+		std::suspend_always final_suspend() noexcept { return {}; }
+		std::suspend_always yield_value(int value) { current_value = value; return {}; }
+
+		void return_void() {}
+		void unhandled_exception() { std::terminate(); }
+	};
+
+	std::coroutine_handle<promise_type> handle;
+
+	~Generator() { if (handle) handle.destroy(); }
+
+	bool next() { handle.resume(); return !handle.done(); }
+	int value() { return handle.promise().current_value; }
+};
+
+Generator counter(int value)
+{
+	for (;;)
+	{
+		std::this_thread::sleep_for(std::chrono::seconds{1});
+		co_yield value;
+	}
+}
+
+int main()
+{
+	auto gen = counter(0);
+	auto led = device::Led();
+	
+	while (gen.next())
+		led.tick();
+}