recover.tdf

verilog编写实用多功能电子表

SUBDESIGN recover 
(
	clk : INPUT;
	go  : INPUT; 
	ok	: OUTPUT;
)
VARIABLE
	sequence : MACHINE 
				OF BITS (q[2..0])
				WITH STATES (	
					idle, 
					one, 
					two, 
					three, 
					four, 
	illegal1, 	
	illegal2, 	
	illegal3);
BEGIN
	sequence.clk = clk;

	CASE sequence IS
		WHEN idle =>
			IF go THEN
				sequence = one;
			END IF;
		WHEN one =>
			sequence = two;
		WHEN two =>
			sequence = three;
		WHEN three =>
			sequence = four;
		WHEN OTHERS =>
			sequence = idle;
	END CASE;

	ok = (sequence == four);
END;