Null video driver: Add driver parameter to run until exit

src/video/null_v.cpp

@@ -19,6 +19,8 @@
 /** Factory for the null video driver. */
 static FVideoDriver_Null iFVideoDriver_Null;
 
+extern bool _exit_game;
+
 const char *VideoDriver_Null::Start(const char * const *parm)
 {
 #ifdef _MSC_VER
@@ -27,6 +29,7 @@ const char *VideoDriver_Null::Start(const char * const *parm)
 #endif
 
 	this->ticks = GetDriverParamInt(parm, "ticks", 1000);
+	this->until_exit = GetDriverParamBool(parm, "until_exit");
 	_screen.width  = _screen.pitch = _cur_resolution.width;
 	_screen.height = _cur_resolution.height;
 	_screen.dst_ptr = nullptr;
@@ -44,12 +47,17 @@ void VideoDriver_Null::MakeDirty(int left, int top, int width, int height) {}
 
 void VideoDriver_Null::MainLoop()
 {
-	uint i;
+	if (this->until_exit) {
-
+		while (!_exit_game) {
-	for (i = 0; i < this->ticks; i++) {
 			GameLoop();
 			UpdateWindows();
 		}
+	} else {
+		for (int i = 0; i < this->ticks; i++) {
+			GameLoop();
+			UpdateWindows();
+		}
+	}
 }
 
 bool VideoDriver_Null::ChangeResolution(int w, int h) { return false; }

src/video/null_v.h

@@ -17,7 +17,8 @@
 /** The null video driver. */
 class VideoDriver_Null : public VideoDriver {
 private:
-	uint ticks; ///< Amount of ticks to run.
+	int ticks; ///< Amount of ticks to run.
+	bool until_exit;
 
 public:
 	const char *Start(const char * const *param) override;