多种基本功能的Verilog代码实现，包括多路选择器，二进制到BCD码转换，二进制到格雷码转换，7段译码器，8位数据锁存器，移位寄存器等等多种功能。(Verilog code implementation of a variety of basic functions, including multiplexer, binary to BCD code conversion, binary to Gray code conversion, 7-segment decoder, 8-bit dat