1 files changed, 15 insertions, 9 deletions

diff --git a/basys3/basys3.srcs/ppu_comp.vhd b/basys3/basys3.srcs/ppu_comp.vhd
index e79738f..30b161c 100644
--- a/basys3/basys3.srcs/ppu_comp.vhd
+++ b/basys3/basys3.srcs/ppu_comp.vhd
@@ -2,35 +2,41 @@ library ieee;
 use ieee.std_logic_1164.all;
 use work.ppu_consts.all;
 
-entity ppu_comp is port ( 
-	FG_HIT : in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
-	BG_EN : out std_logic;
-	FG_EN : out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0));
+entity ppu_comp is port (
+	OE : in std_logic; -- global output enable (screen active)
+	FG_HIT : in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0); -- foreground hit array
+	BG_EN : out std_logic; -- background enable output
+	FG_EN : out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0)); -- foreground enable output
 end ppu_comp;
 
 architecture Behavioral of ppu_comp is
 	signal FG_HIT_EMPTY : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0) := (others => '0');
+	signal TMP_BG_EN : std_logic; -- background enable output
+	signal TMP_FG_EN : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0); -- foreground enable output
 begin
+	BG_EN <= TMP_BG_EN and OE;
+	FG_EN <= TMP_FG_EN and OE;
+
 	process (FG_HIT)
 		variable HIT : boolean := false;
 	begin
 		-- check if FG_HIT is not empty
 		if FG_HIT /= FG_HIT_EMPTY then
-			BG_EN <= '0';
+			TMP_BG_EN <= '0';
 			for i in 0 to PPU_FG_SPRITE_COUNT-1 loop
 				-- if FG_HIT is the first one then enable it
 				if(FG_HIT(i) = '1' and HIT = false) then
-					FG_EN(i) <= '1';
+					TMP_FG_EN(i) <= '1';
 					HIT := true;
 				else
 					-- make rest low
-					FG_EN(i) <= '0';
+					TMP_FG_EN(i) <= '0';
 				end if;
 			end loop;
 			HIT := false;
 		else
-			BG_EN <= '1';
-			FG_EN <= (others => '0');
+			TMP_BG_EN <= '1';
+			TMP_FG_EN <= (others => '0');
 		end if;
 	end process;
 end Behavioral;