bcddecoder_4_10.vhd

将BCD码的转换为四位二进制,实现是一个十线输入,四线输出的转换功能

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY bcddecoder_4_10 IS
PORT (datain  : IN  STD_LOGIC_VECTOR (1 TO 9);
      dataout : OUT STD_LOGIC_VECTOR (3 DOWNTO 0)
      );
END ENTITY bcddecoder_4_10 ;

ARCHITECTURE ONE OF bcddecoder_4_10 IS
BEGIN 
  PROCESS( datain )
     BEGIN 
       IF ( datain="111111111" ) THEN
           dataout<= "1111";
       ELSE
          IF  ( datain (9) ='0' ) THEN
            dataout <="0110" ;
          ELSIF  ( datain (8) ='0' ) THEN
            dataout <="0111" ; 
          ELSIF  ( datain (7) ='0' ) THEN
            dataout <="1000" ; 
          ELSIF  ( datain (6) ='0' ) THEN
            dataout <="1001" ;
          ELSIF  ( datain (5) ='0' ) THEN
            dataout <="1010" ;
          ELSIF  ( datain (4) ='0' ) THEN
            dataout <="1011" ; 
          ELSIF  ( datain (3) ='0' ) THEN
            dataout <="1100" ; 
          ELSIF  ( datain (2) ='0' ) THEN
            dataout <="1101" ;
          ELSIF  ( datain (1) ='0' ) THEN
            dataout <="1110" ; 
          ELSE
             dataout <="1111" ;
          END IF ;
		END IF;
      END PROCESS ;
END ARCHITECTURE ONE ;