-- 庫聲明
library IEEE;
use IEEE.STD_LOGIC_1164.all;
-- 實體聲明
entity counter is
	generic (
	MAX_COUNT : integer := 66 );
	port (
	clk : in std_logic;
	reset_n : in std_logic;      --復位信號
	ce : in std_logic;           --使能信號
	overflow : out std_logic );  --計數到達上閾的提示信號
end counter;

--}} End of automatically maintained section
-- 結構體
architecture counter of counter is

signal count : integer;

begin

	-- enter your statements here --
	-- 主過程
	main: process( clk, reset_n )
	begin
		-- 判斷復位信號
		if reset_n = '0' then
			count <= 0;
			overflow <= '0';
		-- 時鐘信號的上升沿動作
		elsif rising_edge(clk) and ce = '1' then
			-- 在計數上閾時候輸出提示信號overflow
			if count = MAX_COUNT-1 then
				count <= 0;
				overflow <= '1';
			-- 恢復提示信號overflow為低
			elsif count = 0 then
				count <= count+1;
				overflow <= '0';
			else
				count <= count+1;
			end if;
		end if;
	end process;

end counter;