ENTITY detect IS
  PORT (x, clk : IN BIT;
        z : OUT BIT);
END detect;

ARCHITECTURE detect OF detect IS
BEGIN
  PROCESS (clk)
    VARIABLE temp : BIT_VECTOR (3 DOWNTO 0) := "0000";
    VARIABLE count : INTEGER RANGE 0 TO 4 := 0;
  BEGIN
    IF (clk = '1') THEN
      z<= '0';
      count := count + 1;
      temp := temp (2 DOWNTO 0) & X;
      IF (count = 4) THEN
        IF (temp = "1100" OR temp = "1001") THEN
          Z <= '1';
        END IF;
        count := 0;
        temp := "0000";
      END IF;
    END IF;
  END PROCESS;
END detect;