Subversion Repositories gfir

----------

--! @file

--! @brief This is the supporting package. \b "JUST EDIT THIS FILE"

----------

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

package fir_pkg is

        type int_vector is array (natural range <>) of integer;

        constant coeff : int_vector := (-51,25,128,77,-203,-372,70,1122,2047,2047,1122,70,-372,-203,77,128,25,-51); --! Filter coefficients defined in the fir_pkg.vhd

        -- Q 12, N 18

        constant quantization   : positive := 12; --! Filter quantization bit-width

        constant order          : natural  := coeff'length;

        constant width_out      : natural  := 15;

        -- Global signals for internal debugging

        signal g_multi_add   : std_logic_vector((order-1)*width_out-1 downto 0);

        signal g_add_delay   : std_logic_vector((order-2)*width_out-1 downto 0);

        signal g_delay_add   : std_logic_vector((order-1)*width_out-1 downto 0);

        signal g_multi_delay : std_logic_vector(width_out-1 downto 0);

        function binary_width (

                x : natural)

        return natural;

        function EOp (

                M : positive

                )

        return natural;

        function EOn (

                M : positive

                )

        return natural;

end fir_pkg;

package body fir_pkg is

        function binary_width (

                x : natural)

        return natural is

                variable y      : integer;

                variable count  : natural;

                begin

                y := abs(x);

                count := 0;

                while y > 0 loop

                        y := y/2;

                        count := count + 1;

                end loop;

                return count;

                end function;

        function EOp (

                M : positive

                )

        return natural is

                begin

                        if (M mod 2) = 0 then

                                return M/2-1;

                        else

                                return M/2;

                        end if;

                end function;

        function EOn (

                M : positive

                )

        return natural is

                begin

                        if (M mod 2) = 0 then

                                return M/2-1;

                        else

                                return M/2-1;

                        end if;

                end function;

end fir_pkg;