说明：  该程序用VHDL硬件描述语言编写而成,已调试通过,程序运行后可实现三分频,这样就用软件设计代替了硬件设计,方便,稳定,不需要硬件调试!
(the procedures used VHDL hardware description language, prepared debugging has passed, After running third frequency can be realized, so software designed to replace the hardware design, convenience, stability, no hardware debugging!)