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--This library is free software; you can redistribute it and/or

--modify it under the terms of the GNU Lesser General Public

--License as published by the Free Software Foundation; either

--version 2.1 of the License, or (at your option) any later version.

--This library is distributed in the hope that it will be useful,

--but WITHOUT ANY WARRANTY; without even the implied warranty of

--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

--Lesser General Public License for more details.

--You should have received a copy of the GNU Lesser General Public

--License along with this library; if not, write to the Free Software

--Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

-- e_mail : j.l.nunez-yanez@byacom.co.uk

---------------------------------------------

--  ENTITY       = PARSER_CONCATENATOR     --

--  version      = 1.0                     --

--  last update  = 30/05/00                --

--  author       = Jose Nunez              --

---------------------------------------------

-- FUNCTION

-- The parser concatenator adds more data when required

--  PIN LIST

--  DATA_IN_BUFFER  = 32 bits of data comming from the buffer

--  DATA_OLD = old data

--  LENGTH_OLD = old length

--  DATA_NEW = new data negerated

--  LENGTH_OUT = new length generated 

library ieee;

use ieee.std_logic_1164.all;

entity PARSER_CONCATENATOR is

port

        (

        DATA_IN_BUFFER : in bit_vector(31 downto 0);

        ENABLE: in bit;

        READ : in bit;

        DATA_OLD : in bit_vector(55 downto 0);

        LENGTH_OLD : in bit_vector(2 downto 0);

        DATA_NEW : out bit_vector(55 downto 0);

        LENGTH_NEW : out bit_vector(2 downto 0)

        );

end PARSER_CONCATENATOR;

architecture STRUCTURAL of PARSER_CONCATENATOR is

begin

LENGTH_CALC : process(LENGTH_OLD,ENABLE, READ)

begin

if (ENABLE = '1' and READ = '1') then

   case LENGTH_OLD is

                when "011" => LENGTH_NEW <= "111";

                when "010" => LENGTH_NEW <= "110";

            when "001" => LENGTH_NEW <= "101";

                when "000" => LENGTH_NEW <= "100";

                when others => LENGTH_NEW <= LENGTH_OLD;

   end case;

else

        LENGTH_NEW <= LENGTH_OLD;

end if;

end process LENGTH_CALC;

CODE_CALC : process(LENGTH_OLD , DATA_IN_BUFFER , DATA_OLD)

begin

case LENGTH_OLD is

    when "000" => DATA_NEW(55 downto 0)  <= DATA_IN_BUFFER & "000000000000000000000000";

    when "001" => DATA_NEW(55 downto 0)  <= DATA_OLD(55 downto 48) & DATA_IN_BUFFER &  "0000000000000000";

    when "010" => DATA_NEW(55 downto 0)  <= DATA_OLD(55 downto 40) & DATA_IN_BUFFER & "00000000";

    when "011" => DATA_NEW(55 downto 0)  <= DATA_OLD(55 downto 32) & DATA_IN_BUFFER;

    when others   => DATA_NEW(55 downto 0) <= DATA_OLD(55 downto 0);

end case;

end process CODE_CALC;

end STRUCTURAL;