How to transform a binary 4 digit number into a 8 bit number for a seven segment display, characters 0 to 15 i.e. Hexadecimal.

这是一段用VHDL语言写的24进制计数器，用数码管显示，我用了例化语句，分为24进制计数器模块，十位译码，个位译码，用cycloneII ep2系列实验板验证，能计数0~23。此程序还可以修改为100以内任何进制计数器。-This is a written in VHDL language 24 a binary counter, using digital tube display, I used the instantiated statements, divided into 24 hex