数字钟代码，用VHDL语言设计一个数字钟系统，该系统具有显示时、分、秒的功能，具有较时功能，具有整点报时功能。-Digital Clock code using VHDL language to design a digital clock system, which has a display hours, minutes and seconds functions, when a more functional, with the whole point timekeeping functi