Let us start here, from square one. No, from Zero!

api/serial.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <string>
+#include <thread>
+#include <windows.h>
+
+namespace api {
+
+    class Controller;
+    struct ClientState;
+
+    class SerialController {
+    public:
+
+        SerialController(Controller *controller, std::string port, DWORD baud);
+        ~SerialController();
+
+        void open_port();
+        void free_port();
+
+    private:
+        Controller *controller = nullptr;
+        std::string port = "";
+        DWORD baud = 0;
+        HANDLE handle = INVALID_HANDLE_VALUE;
+        std::thread *thread = nullptr;
+        ClientState *state = nullptr;
+        bool running = true;
+    };
+}