signal x1_1 : signed(23 downto 0) := (others => '0');		-- x(n-1)
	signal x2_1 : signed(23 downto 0) := (others => '0');		-- x(n-2)
	signal y1_1 : signed(23 downto 0) := (others => '0');		-- y(n-1)
	signal y2_1 : signed(23 downto 0) := (others => '0');		-- y(n-2)

	signal x1_2 : signed(23 downto 0) := (others => '0');		-- x(n-3)
	signal x2_2 : signed(23 downto 0) := (others => '0');		-- x(n-4)
	signal y1_2 : signed(23 downto 0) := (others => '0');		-- y(n-3)
	signal y2_2 : signed(23 downto 0) := (others => '0');		-- y(n-4)

	signal x1_3 : signed(23 downto 0) := (others => '0');		-- x(n-5)
	signal x2_3 : signed(23 downto 0) := (others => '0');		-- x(n-6)
	signal y1_3 : signed(23 downto 0) := (others => '0');		-- y(n-5)
	signal y2_3 : signed(23 downto 0) := (others => '0');		-- y(n-6)

	signal x1_4 : signed(23 downto 0) := (others => '0');		-- x(n-7)
	signal x2_4 : signed(23 downto 0) := (others => '0');		-- x(n-8)
	signal y1_4 : signed(23 downto 0) := (others => '0');		-- y(n-7)
	signal y2_4 : signed(23 downto 0) := (others => '0');		-- y(n-8)

	signal x1_5 : signed(23 downto 0) := (others => '0');		-- x(n-9)
	signal x2_5 : signed(23 downto 0) := (others => '0');		-- x(n-10)
	signal y1_5 : signed(23 downto 0) := (others => '0');		-- y(n-9)
	signal y2_5 : signed(23 downto 0) := (others => '0');		-- y(n-10)

	signal x1_6 : signed(23 downto 0) := (others => '0');		-- x(n-11)
	signal x2_6 : signed(23 downto 0) := (others => '0');		-- x(n-12)
	signal y1_6 : signed(23 downto 0) := (others => '0');		-- y(n-11)
	signal y2_6 : signed(23 downto 0) := (others => '0');		-- y(n-12)

	signal x1_7 : signed(23 downto 0) := (others => '0');		-- x(n-13)
	signal x2_7 : signed(23 downto 0) := (others => '0');		-- x(n-14)
	signal y1_7 : signed(23 downto 0) := (others => '0');		-- y(n-13)
	signal y2_7 : signed(23 downto 0) := (others => '0');		-- y(n-14)

	signal x1_8 : signed(23 downto 0) := (others => '0');		-- x(n-15)
	signal x2_8 : signed(23 downto 0) := (others => '0');		-- x(n-16)
	signal y1_8 : signed(23 downto 0) := (others => '0');		-- y(n-15)
	signal y2_8 : signed(23 downto 0) := (others => '0');		-- y(n-16)
		
	signal x1_9 : signed(23 downto 0) := (others => '0');		-- x(n-17)
	signal x2_9 : signed(23 downto 0) := (others => '0');		-- x(n-18)
	signal y1_9 : signed(23 downto 0) := (others => '0');		-- y(n-17)
	signal y2_9 : signed(23 downto 0) := (others => '0');		-- y(n-18)
		
	signal x1_10 : signed(23 downto 0) := (others => '0');	-- x(n-19)
	signal x2_10 : signed(23 downto 0) := (others => '0');	-- x(n-20)
	signal y1_10 : signed(23 downto 0) := (others => '0');	-- y(n-19)
	signal y2_10 : signed(23 downto 0) := (others => '0');	-- y(n-20)
		
	signal x1_11 : signed(23 downto 0) := (others => '0');	-- x(n-21)
	signal x2_11 : signed(23 downto 0) := (others => '0');	-- x(n-22)
	signal y1_11 : signed(23 downto 0) := (others => '0');	-- y(n-21)
	signal y2_11 : signed(23 downto 0) := (others => '0');	-- y(n.22)
		
	signal x1_12 : signed(23 downto 0) := (others => '0');	-- x(n-23)
	signal x2_12 : signed(23 downto 0) := (others => '0');	-- x(n-24)
	signal y1_12 : signed(23 downto 0) := (others => '0');	-- y(n-23)
	signal y2_12 : signed(23 downto 0) := (others => '0');	-- y(n-24)
		
	signal x1_13 : signed(23 downto 0) := (others => '0');	-- x(n-25)
	signal x2_13 : signed(23 downto 0) := (others => '0');	-- x(n-26)
	signal y1_13 : signed(23 downto 0) := (others => '0');	-- y(n-25)
	signal y2_13 : signed(23 downto 0) := (others => '0');	-- y(n-26)

	signal x1_14 : signed(23 downto 0) := (others => '0');	-- x(n-27)
	signal x2_14 : signed(23 downto 0) := (others => '0');	-- x(n-28)
	signal y1_14 : signed(23 downto 0) := (others => '0');	-- y(n-27)
	signal y2_14 : signed(23 downto 0) := (others => '0');	-- y(n-28)

	-- Zwischenspeicher der Koeffizienten und 
	-- Signale zur einzelnen Berechnung einer Kaskade,
	-- sowie von Zwischenergebnissen
	signal b0 : signed(63 downto 0);
	signal b1 : signed(63 downto 0);
	signal b2 : signed(63 downto 0);
	signal a1 : signed(63 downto 0);
	signal a2 : signed(63 downto 0);
	signal x1 : signed(23 downto 0);
	signal x0 : signed(23 downto 0);
	signal x2 : signed(23 downto 0);
	signal y1 : signed(23 downto 0);
	signal y2 : signed(23 downto 0);
	signal tmp1 : signed(87 downto 0);
	signal tmp2 : signed(87 downto 0);
	signal yn : signed(23 downto 0);
	signal mul_a_1 : signed(23 downto 0);
	signal mul_b_1 : signed(63 downto 0);
	signal mul_r_1 : signed(87 downto 0);
	signal mul_a_2 : signed(23 downto 0);
	signal mul_b_2 : signed(63 downto 0);
	signal mul_r_2 : signed(87 downto 0);

	-- Multiplizierer Komponente (Megafunctions LPM_MULT)
	component lpm_mult0
		port
		(
			dataa		: IN signed (23 DOWNTO 0);
			datab		: IN signed (63 DOWNTO 0);
			result	: OUT signed (87 DOWNTO 0)
		);
	end component;
	
begin
	
	-- Multiplizierer Ports zuweisen
	lpm_mult0_1 : lpm_mult0 port map (mul_a_1, mul_b_1, mul_r_1);
	lpm_mult0_2 : lpm_mult0 port map (mul_a_2, mul_b_2, mul_r_2);
	
	-- Filterprozess
	process begin
	
		-- Warten auf steigende Flanke des 50 MHz Taktes
		wait until rising_edge(clk_50MHz);
		
		-- Bei Freigabeimpuls alle Zähler zurücksetzen
		if (en = '0') then
			counter <= (others => '0');
			section <= (others => '0');
		else
			case counter is
				when x"00" => 
					-- Koeffizienten an die entsprechenden Signale übergeben je nach gewählter Kaskade gemäß section
					case section is 
						when x"0" => a1 <= b1_1;   a2 <= a2_1;   b0 <= b0_1;   b1 <= b1_1;   b2 <= b2_1;   x0 <= x;   x1 <= x1_1;  x2 <= x2_1;  y1 <= y1_1;  y2 <= y2_1;
						when x"1" => a1 <= b1_2;   a2 <= a2_2;   b0 <= b0_2;   b1 <= b1_2;   b2 <= b2_2;   x0 <= yn;  x1 <= x1_2;  x2 <= x2_2;  y1 <= y1_2;  y2 <= y2_2;
						when x"2" => a1 <= b1_3;   a2 <= a2_3;   b0 <= b0_3;   b1 <= b1_3;   b2 <= b2_3;   x0 <= yn;  x1 <= x1_3;  x2 <= x2_3;  y1 <= y1_3;  y2 <= y2_3;
						when x"3" => a1 <= b1_4;   a2 <= a2_4;   b0 <= b0_4;   b1 <= b1_4;   b2 <= b2_4;   x0 <= yn;  x1 <= x1_4;  x2 <= x2_4;  y1 <= y1_4;  y2 <= y2_4;
						when x"4" => a1 <= b1_5;   a2 <= a2_5;   b0 <= b0_5;   b1 <= b1_5;   b2 <= b2_5;   x0 <= yn;  x1 <= x1_5;  x2 <= x2_5;  y1 <= y1_5;  y2 <= y2_5;
						when x"5" => a1 <= b1_6;   a2 <= a2_6;   b0 <= b0_6;   b1 <= b1_6;   b2 <= b2_6;   x0 <= yn;  x1 <= x1_6;  x2 <= x2_6;  y1 <= y1_6;  y2 <= y2_6;
						when x"6" => a1 <= b1_7;   a2 <= a2_7;   b0 <= b0_7;   b1 <= b1_7;   b2 <= b2_7;   x0 <= yn;  x1 <= x1_7;  x2 <= x2_7;  y1 <= y1_7;  y2 <= y2_7;
						when x"7" => a1 <= b1_8;   a2 <= a2_8;   b0 <= b0_8;   b1 <= b1_8;   b2 <= b2_8;   x0 <= yn;  x1 <= x1_8;  x2 <= x2_8;  y1 <= y1_8;  y2 <= y2_8;
						when x"8" => a1 <= b1_9;   a2 <= a2_9;   b0 <= b0_9;   b1 <= b1_9;   b2 <= b2_9;   x0 <= yn;  x1 <= x1_9;  x2 <= x2_9;  y1 <= y1_9;  y2 <= y2_9;
						when x"9" => a1 <= b1_10;  a2 <= a2_10;  b0 <= b0_10;  b1 <= b1_10;  b2 <= b2_10;  x0 <= yn;  x1 <= x1_10; x2 <= x2_10; y1 <= y1_10; y2 <= y2_10;
						when x"A" => a1 <= b1_11;  a2 <= a2_11;  b0 <= b0_11;  b1 <= b1_11;  b2 <= b2_11;  x0 <= yn;  x1 <= x1_11; x2 <= x2_11; y1 <= y1_11; y2 <= y2_11;
						when x"B" => a1 <= b1_12;  a2 <= a2_12;  b0 <= b0_12;  b1 <= b1_12;  b2 <= b2_12;  x0 <= yn;  x1 <= x1_12; x2 <= x2_12; y1 <= y1_12; y2 <= y2_12;
						when x"C" => a1 <= b1_13;  a2 <= a2_13;  b0 <= b0_13;  b1 <= b1_13;  b2 <= b2_13;  x0 <= yn;  x1 <= x1_13; x2 <= x2_13; y1 <= y1_13; y2 <= y2_13;
						when x"D" => a1 <= b1_14;  a2 <= a2_14;  b0 <= b0_14;  b1 <= b1_14;  b2 <= b2_14;  x0 <= yn;  x1 <= x1_14; x2 <= x2_14; y1 <= y1_14; y2 <= y2_14;
						when others => null;
					end case;
				-- Berechnung zur Filterung mittels einer Kaskade durchführen
				-- Bei der Berechnung wird folgende Formel angewandt.
				-- y(n) = b0*x(n) + b1*x(n-1) + b2*x(n-2) - a1*y(n-1) - a2*y(n-2)
				when x"01" => mul_a_1 <= x0; mul_b_1 <= b0; mul_a_2 <= x1; mul_b_2 <= b1; 
				when x"02" => tmp1 <= mul_r_1 + mul_r_2;
				when x"03" => mul_a_1 <= x2; mul_b_1 <= b2; mul_a_2 <= y1; mul_b_2 <= a1; 
				when x"04" => tmp2 <= tmp1 + mul_r_1 - mul_r_2;
				when x"05" => mul_a_1 <= y2; mul_b_1 <= a2;
				when x"06" => tmp1 <= tmp2 - mul_r_1;
				when x"07" => yn <= tmp1(82 downto 59);
				when x"08" =>
					-- Zwischenergebnisse links schieben 
					case section is
						when x"0" => x2_1   <= x1_1;   x1_1   <= x0;  y2_1  <= y1_1;  y1_1  <= yn; section <= x"1"; counter <= x"00";
						when x"1" => x2_2   <= x1_2;   x1_2   <= x0;  y2_2  <= y1_2;  y1_2  <= yn; section <= x"2"; counter <= x"00";
						when x"2" => x2_3   <= x1_3;   x1_3   <= x0;  y2_3  <= y1_3;  y1_3  <= yn; section <= x"3"; counter <= x"00";
						when x"3" => x2_4   <= x1_4;   x1_4   <= x0;  y2_4  <= y1_4;  y1_4  <= yn; section <= x"4"; counter <= x"00";
						when x"4" => x2_5   <= x1_5;   x1_5   <= x0;  y2_5  <= y1_5;  y1_5  <= yn; section <= x"5"; counter <= x"00";
						when x"5" => x2_6   <= x1_6;   x1_6   <= x0;  y2_6  <= y1_6;  y1_6  <= yn; section <= x"6"; counter <= x"00";
						when x"6" => x2_7   <= x1_7;   x1_7   <= x0;  y2_7  <= y1_7;  y1_7  <= yn; section <= x"7"; counter <= x"00";
						when x"7" => x2_8   <= x1_8;   x1_8   <= x0;  y2_8  <= y1_8;  y1_8  <= yn; section <= x"8"; counter <= x"00";
						when x"8" => x2_9   <= x1_9;   x1_9   <= x0;  y2_9  <= y1_9;  y1_9  <= yn; section <= x"9"; counter <= x"00";
						when x"9" => x2_10  <= x1_10;  x1_10  <= x0;  y2_10 <= y1_10; y1_10 <= yn; section <= x"A"; counter <= x"00";
						when x"A" => x2_11  <= x1_11;  x1_11  <= x0;  y2_11 <= y1_11; y1_11 <= yn; section <= x"B"; counter <= x"00";
						when x"B" => x2_12  <= x1_12;  x1_12  <= x0;  y2_12 <= y1_12; y1_12 <= yn; section <= x"C"; counter <= x"00";
						when x"C" => x2_13  <= x1_13;  x1_13  <= x0;  y2_13 <= y1_13; y1_13 <= yn; section <= x"D"; counter <= x"00";
						when x"D" => x2_14  <= x1_14;  x1_14  <= x0;  y2_14 <= y1_14; y1_14 <= yn; y <= yn; counter <= x"09";
						when others => null;
					end case;
				when others => null;
			end case;
			if (counter < x"08") then counter <= counter + 1; end if;
		end if;
	end process;
end behavior;