用VHDL编程实现一条主干道，一条乡间公路。组成十字路口，要求优先保证主干道通行。有MR（主红）、MY（主黄）、MG（主绿）、CR(乡红)、CY（乡黄）、CG（乡绿）六盏交通灯需要控制；交通灯由绿→红有4秒黄灯亮的间隔时间，由红→绿没有间隔时间；系统有MRCY、MRCG、MYCR、MGCR四个状态；-VHDL programming to a main road, a country road. Composed of a crossroads, requiring priority to ensuring the main road traffic. MR (red), MY (main yellow), MG (green), CR (Township red), CY (Township yellow), CG (Township Green) six traffic lights need to be controlled　traffic lights green → red four seconds of yellow light intervals by red → green interval of time　system MRCY, MRCG, MYCR, MGCR four states