library ieee;
use ieee.std_logic_1164.ALL;
use ieee.std_logic_ARITH.ALL;
use ieee.std_logic_UNSIGNED.ALL;

entity vga is port ( 
			CLOCK_50 	          : in std_logic;	
			GPIO_1_D		        : out std_logic_vector(33 downto 0)  
			);
end vga;

architecture Behavioral of vga is

			--Sync Signals
  signal h_sync	          :	std_logic;
  signal v_sync           : std_logic;
			
      --Video Enables
  signal video_en         :	std_logic;
	signal horizontal_en    :	std_logic; 
	signal vertical_en	    : std_logic;
			--Color Signals
  signal red_signal       :	std_logic;
	signal green_signal     :	std_logic;
	signal blue_signal	    : std_logic;
			--Sync Counters 
  signal h_cnt            : std_logic_vector(10 downto 0) := (others => '0');
	signal v_cnt            : std_logic_vector(10 downto 0) := (others => '0');

begin

  video_en <= horizontal_en AND vertical_en;		
		
process
  begin

	wait until(CLOCK_50'EVENT) AND (CLOCK_50 = '1');
	
	--Generate Screen
	if (v_cnt >= 0) AND  (v_cnt <= 799) then
    red_signal <= '0';
		green_signal <= '0';
		blue_signal <= '0';
			if (((v_cnt >= 200) AND (v_cnt <= 400)) AND ((h_cnt >= 300) AND (h_cnt <= 500))) then
				red_signal <= '1';
			end if;
	end if;
		
	--Generate Horizontal Sync
	if (h_cnt <= 975) AND (h_cnt >= 855) then
		h_sync <= '0';
	else
		h_sync <= '1';
	end if;
		
		--Reset Horizontal Counter
	if (h_cnt = 1039) then
		h_cnt <= "00000000000";
	else
		h_cnt <= h_cnt + 1;
	end if;			
	
	--Reset Vertical Counter
	if (v_cnt >= 665) AND (h_cnt >= 1039) then
		v_cnt <= "00000000000";
	elsif (h_cnt = 1039) then
		v_cnt <= v_cnt + 1;
	end if;
		
		--Generate Vertical Sync
	if (v_cnt <= 642) AND (v_cnt >= 636) then
		v_sync <= '0';	
	else
		v_sync <= '1';
	end if;
	
	--Generate Horizontal Data
	if (h_cnt <= 799) then
		horizontal_en <= '1';
	else
		horizontal_en <= '0';
	end if;
	
	--Generate Vertical Data
	if (v_cnt <= 599) then
		vertical_en <= '1';
	else
		vertical_en <= '0';
	end if;
	
	--Assign Physical Signals To VGA
	--red		<= red_signal AND video_en;
	GPIO_1_D(1)	<= red_signal AND video_en;
	--green   <= green_signal AND video_en;
	GPIO_1_D(3)	<= green_signal AND video_en;
	--blue	<= blue_signal AND video_en;
	GPIO_1_D(5)	<= blue_signal AND video_en;
	
	--hsync	<= h_sync;
	GPIO_1_D(7) <= h_sync;
	--vsync	<= v_sync;		
	GPIO_1_D(9) <= v_sync;	
end process;
				
end Behavioral;