用VHDL语言编写的VGA显示彩条

用VHDL语言编写的彩条显示，部分程序如下: architecture behave of VGA is -- horizontal timing signals constant h_data: integer:=640; constant h_front: integer:=16; constant h_back: integer:=48; constant h_sync: integer:=96; constant h_period: integer:= h_sync + h_data + h_front + h_back; -- vertical timing signals constant v_data: integer:=480; constant v_front: integer:=11; constant v_back: integer:=32; constant v_sync: integer:=2; constant v_period: integer:= v_sync + v_data + v_front + v_back; signal henable, venable : std_logic; signal clk50M : std_logic; signal hcnt: std_logic_vector(9 downto 0); -- horizontal pixel counter signal vcnt: std_logic_vector(9 downto 0); -- vertical line counter