traffic_control.vhd

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LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY traffic_control IS
	PORT(
		 clk        :IN STD_LOGIC;
         c1,c2,c3   :OUT STD_LOGIC;
         w1,w2,w3   :IN STD_LOGIC;
         r1,r2      :OUT STD_LOGIC;
         y1,y2      :OUT STD_LOGIC;
         g1,g2      :OUT STD_LOGIC;
         reset      :IN STD_LOGIC);
  END traffic_control;

ARCHITECTURE  a OF traffic_control IS
 TYPE STATE_SPACE IS(S0,S1,S2,S3);
 SIGNAL  state:STATE_SPACE;
BEGING
  PROCESS(clk)
  BEGIN
   IF reset='1'THEN
		state<=S0;
   ELSIF(clk'EVENT AND clk='1')THEN
        CASE state IS
			WHEN S0=>
					IF w1='1'THEN
                         state<=S1;
                    END IF;
            WHEN S1=>
                    IF w2='1'THEN
                         state<=S2;
                    END IF;
            WHEN S2=>
                    IF w3='1'THEN
                         state<=S3;
                    END IF;

            WHEN S3=>
                    IF w2='1'THEN
                         state<=S0;
                    END IF;
          END CASE;
       END IF;
  END PROCESS;
  c1<='1'  WHEN state=S0 ELSE '0';
  c2<='1'  WHEN state=S1 OR state=S3 ELSE '0';
  c3<='1'  WHEN state=S2 ELSE '0';
  r1<='1'  WHEN state=S1 OR state=S0 ELSE '0';
  y1<='1'  WHEN state=S3 ELSE '0';
  g1<='1'  WHEN state=S2 ELSE '0';
  r2<='1'  WHEN state=S2 OR state=S3 ELSE '0';
  y2<='1'  WHEN state=S1 ELSE '0';
  g2<='1'  WHEN state=S0 ELSE '0';
END a;