b_to_d.vhd

用VHDL语言将二进制数据转换成十进制数据

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY B_to_D IS
PORT(AIN:IN STD_LOGIC_VECTOR(25 DOWNTO 0);
CLK:IN STD_LOGIC;
SET107X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET106X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET105X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET104X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET103X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET102X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET101X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SET100X:OUT STD_LOGIC_VECTOR(3 DOWNTO 0));
END B_to_D;
ARCHITECTURE BEHAV OF B_to_D IS
TYPE STATES IS (S0,S1,S2,S3,S4,S5,S6,S7);
SIGNAL STATE: STATES;
BEGIN
PROCESS(CLK,AIN)
    VARIABLE   TEMP : STD_LOGIC_VECTOR(3 DOWNTO 0);
    VARIABLE   A    : STD_LOGIC_VECTOR(25 DOWNTO 0);

BEGIN
IF CLK'EVENT and CLK='1' THEN
        CASE STATE IS
        WHEN S0 =>         
			A:=AIN;
           	TEMP:="0000";
            STATE<=S1;
        WHEN S1 =>  
           	IF (A>=10000000) THEN
           		A:=A-10000000;
          		TEMP:=TEMP+1;
        		STATE<=S1;
          	ELSE
        		SET107X<=TEMP;
         		TEMP:="0000";
          		STATE<=S2;
            END IF;
        WHEN S2 =>  
            IF (A>=1000000) THEN
            	A:=A-1000000;
             	TEMP:=TEMP+1;
           		STATE<=S2;
          	ELSE
             	SET106X<=TEMP;
          		TEMP:="0000";
        		STATE<=S3;
           	END IF;
        WHEN S3 =>  
           	IF (A>=100000) THEN
     			A:=A-100000;
    			TEMP:=TEMP+1;
           		STATE<=S3;
      		ELSE
           		SET105X<=TEMP;
             	TEMP:="0000";
       			STATE<=S4;
      		END IF;
        WHEN S4 =>  
    		IF (A>=10000) THEN
               	A:=A-10000;
    			TEMP:=TEMP+1;
            	STATE<=S4;
           	ELSE
            	SET104X<=TEMP;
               	TEMP:="0000";
                STATE<=S5;
            END IF;
        WHEN S5 =>  
      		IF (A>=1000) THEN
            	A:=A-1000;
           		TEMP:=TEMP+1;
             	STATE<=S5;
           	ELSE
            	SET103X<=TEMP;
           		TEMP:="0000";
            	STATE<=S6;
           	END IF;
        WHEN S6 =>  
          	IF (A>=100) THEN
            	A:=A-100;
            	TEMP:=TEMP+1;
           		STATE<=S6;
           	ELSE
              	SET102X<=TEMP;
           		TEMP:="0000";
               	STATE<=S7;
      		END IF;
        WHEN S7 => 
	       	IF (A>=10) THEN
	        	A:=A-10;
	       		TEMP:=TEMP+1;
	        	STATE<=S7;
	        ELSE
	      		SET101X<=TEMP;
	       		SET100X<=A(3 DOWNTO 0);
	         	STATE<=S0;
	        END IF;
       	WHEN OTHERS => STATE<=S0;
END CASE;
END IF;
END PROCESS;
END BEHAV;