ripple.vhd

来自「design compile synthesis user guide」· VHDL 代码 · 共 83 行

 Library IEEE;
 use IEEE.std_logic_1164.all;
 use IEEE.std_logic_arith.all;

 entity RIPPLE is

      Port ( clk : In    std_logic;
             reset : In    std_logic;
             count : BUFFER UNSIGNED (3 downto 0));
 end RIPPLE;

 architecture BEHAVIORAL of RIPPLE is
	signal count0, count1, count2 : std_logic;
	begin

	process(count)
	begin
	count0 <= count(0);
	count1 <= count(1);
	count2 <= count(2);
	end process;

	process(reset,clk)
	begin
	if (reset = '0') then
		count(0) <= '0';
	elsif (clk'event and clk = '1')then
		if (count(0) = '1') then
			count(0) <= '0';
		else
			count(0) <= '1';
		end if;
	end if;
	end process;

	process(reset,count0)
	begin
	if (reset = '0') then
		count(1) <= '0';
	elsif (count0'event and count0 = '1')then
		if (count(1) = '1') then
			count(1) <= '0';
		else
			count(1) <= '1';
		end if;
	end if;
	end process;

	process(reset,count1)
	begin
	if (reset = '0') then
		count(2) <= '0';
	elsif (count1'event and count1 = '1')then
		if (count(2) = '1') then
			count(2) <= '0';
		else
			count(2) <= '1';
		end if;
	end if;
	end process;

	process(reset,count2)
	begin
	if (reset = '0') then
		count(3) <= '0';
	elsif (count2'event and count2 = '1')then
		if (count(3) = '1') then
			count(3) <= '0';
		else
			count(3) <= '1';
		end if;
	end if;
	end process;
 end BEHAVIORAL;

configuration CFG_RIPPLE_BLOCK_BEHAVIORAL of RIPPLE is
        for BEHAVIORAL
 
        end for;
 
end CFG_RIPPLE_BLOCK_BEHAVIORAL;