利用VHDL语言设计一个十字路*通灯控制器，分成两个方向，六个灯。三个灯按合理的顺序亮灭。 两个方向的灯亮时间可以进行调节。-Using VHDL design of a traffic signal controllers, divided into two directions, six lights. Three lights blinking at a reasonable order. Time light can be adjusted in both directions.