一个简单的密码控制的跑表的vhdl代码，6位数码管显示，有顶层文件和底层文件，当密码为：00001111时，为加计数；当密码为：11110000时，为减计数；当密码为：11001100时，停止计数。

-A simple password-controlled stopwatch the vhdl code, 6 digit LED display, a top-level files and the underlying documents, when the password is: 00001111, in order to increase the count　when the password is: 11110000, in order to reduce the count　when the password is : 11001100, stop counting.