应用VHD语言描述一个彩灯控制器，彩灯为21个，每次顺序点亮相邻的四个彩灯，如此循环下去执行，循环的方向可以控制-VHD language to describe the application of a lamp controller, the lantern is 21, each adjacent sequence of four lights lit, and so the cycle continues execution, you can control the direction