-- Scott Sirowy
-- February 7th, 2007
-- Component reads memory and outputs appropriate colors to VGA screen

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;


entity rgb_read is
    Port ( 
		hcount	: in 		std_logic_vector(9 downto 0);
		vcount	: in 		std_logic_vector(8 downto 0);
		input 	: in  	std_logic_vector(3 downto 0);
				
		ram_addr 	: out		std_logic_vector(11 downto 0);
		red 		: out  	std_logic;
		blue 		: out  	std_logic;
		green 	: out  	std_logic
			);
end rgb_read;

architecture arch of rgb_read is

begin


--create an address that will address all 64x48 locations
--Notice we need 6 bits to address 64 horizontal increments, and also 6 bits 
--for 48 vertical increments, if we want a finer grained increment, we simply
--add a few more bits
--
ram_addr <= vcount(8 downto 3) & hcount(9 downto 4);

process(hcount, vcount)
begin

--make sure hcount or vcount are still within the screen window
if (hcount > "1010000000" or vcount > "111100000") then
	red <= '0'; 
	green <= '0';
	blue <= '0';
else
	red <= input(0);
	green <= input(1);
	blue <= input(2);
end if;

end process;

end arch;