1 files changed, 36 insertions, 0 deletions
diff --git a/basys3/basys3.srcs/ppu_comp.vhd b/basys3/basys3.srcs/ppu_comp.vhd
new file mode 100644
index 0000000..e79738f
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_comp.vhd
@@ -0,0 +1,36 @@
+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));
+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');
+begin
+	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';
+			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';
+					HIT := true;
+				else
+					-- make rest low
+					FG_EN(i) <= '0';
+				end if;
+			end loop;
+			HIT := false;
+		else
+			BG_EN <= '1';
+			FG_EN <= (others => '0');
+		end if;
+	end process;
+end Behavioral;