wanted code for distributed arithmetic fir filter

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_SIGNED.ALL;
use IEEE.NUMERIC_STD.ALL;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity subfilt0 is
Port ( dout : out STD_LOGIC_vector(28 downto 0);
clk : in STD_LOGIC;
clk1:in std_logic;
reset : in STD_LOGIC;
din : in STD_LOGIC_vector(7 downto 0));
end subfilt0;

architecture Behavioral of subfilt0 is

component DFF is
port(
q : out STD_LOGIC_vector(27 downto 0); --output connected to the adder
Clk :in std_logic; -- Clock input
d :in STD_LOGIC_vector(27 downto 0) -- Data input from the MCM block.
);
end component;

signal H00,H048 : STD_LOGIC_vector(19 downto 0) := (others => '0');
signal MCM00,MCM01 : STD_LOGIC_vector(27 downto 0) := (others => '0');
signal add_out01: STD_LOGIC_vector(28 downto 0) := (others => '0');
signal Q01 : STD_LOGIC_vector(27 downto 0) := (others => '0');

begin

H00 <= "11111111111111100101";
H048 <= "00000010101101101100";
dff1 : DFF port map(Q01,Clk,MCM00);
p01000rocess(Clk1,reset)
begin

if reset='0' then
dout <= "00000000000000000000000000000";

elsif clk1'event and clk1='1' then

MCM00 <= din * H00;
MCM01 <= din * H048;

add_out01 <= Q01+ MCM01;
dout <= add_out01;
end if;
end process p01000;

end Behavioral;

this is the code in vhdl for 2 coefficient fir filter.for distributed arithmetic form what changes i have to make .whether the above code is correct.This code may generate overflow problem.whether distributed arithmetic solve the problem of overflow .where can i get the the information about distributed arithmetic and vhdl libraries and packages . i tried to increase the output width so that carry over at the last bit can be considered but then also i did not get the desired result. is there any solution to the above problem.

You can generate proper VHDL code by the PDA IP core generator built in the Aldec AHDL simulator, which implements similar distributed arithmetic.