--偶數(shù)倍 分頻電路
--分頻倍數(shù)=2（n+1）

LIBRARY ieee;
USE ieee.std_logic_1164.all; 
USE ieee.std_logic_arith.all; 
USE ieee.std_logic_unsigned.all; 

entity test1 is
	port
	(
		clkin:in std_logic;
		clkout:out std_logic
	);
end test1;

architecture test_a of test1 is
constant n: integer:=3;---------------------
signal count: integer range 0 to n;
signal clk: std_logic;
begin
	process(clkin)
	begin
	if rising_edge(clkin)then
		if(count=n)then
			count<=0;
			clk<=not clk; 
		else
			count<=count+1;
		end if;
	end if;	
	end process;
	clkout<=clk;
end;