Subversion Repositories xmatchpro

--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       = MLD_DPROP   --

--  version      = 1.0         --

--  last update  = 20/07/98    --

--  author       = Jose Nunez  --

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

-- FUNCTION

-- Match location decision down propagation logic.

-- This takes in a column of priority bits and produces a resultant bit vector

-- with only one bit (at most) set. This bit is the first bit set in

-- the input column.

-- This is the down propagation that is required, i.e for equal priorities,

-- the location closest to the top of the table is the one to be chosen.

-- PIN LIST

-- DIN     = input column of bits

-- DOUT    = resultant column of bits

-- FULL_OR = or function of all bits in DIN.

library ieee,dzx;

use ieee.std_logic_1164.all;

entity MLD_DPROP is

port

        (

        DIN : in bit_vector(0 to 15);

        DOUT : out bit_vector(0 to 15);

        FULL_OR : out bit

        );

end MLD_DPROP;

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

--  entity       = MLD_DPROP   --

--  ARCHITECTURE = DOWN        --

--  version      = 1.0         --

--  last update  = 20/07/95    --

--  author       = Mark Gooch  --

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

architecture DOWN of MLD_DPROP is

signal B_ROW : bit_vector(0 to 15);

signal C_ROW : bit_vector(0 to 15);

signal D_ROW : bit_vector(0 to 15);

signal E_ROW : bit_vector(0 to 15);

begin

GEN_B : process (DIN)

begin

for I in 0 to 7 loop

        B_ROW(2*I) <= DIN(2*I);

        B_ROW(2*I+1) <= DIN(2*I+1) or DIN(2*I);

end loop;

end process GEN_B;

GEN_C : process (B_ROW)

begin

for I in 0 to 3 loop

        for J in 0 to 1 loop

                C_ROW(4*I+J) <= B_ROW(4*I+J);

        end loop;

        for J in 2 to 3 loop

                C_ROW(4*I+J) <= B_ROW(4*I+1) or B_ROW(4*I+J);

        end loop;

end loop;

end process GEN_C;

GEN_D : process (C_ROW)

begin

for I in 0 to 1 loop

        for J in 0 to 3 loop

                D_ROW(8*I+J) <= C_ROW(8*I+J);

        end loop;

        for J in 4 to 7 loop

                D_ROW(8*I+J) <= C_ROW(8*I+3) or C_ROW(8*I+J);

        end loop;

end loop;

end process GEN_D;

GEN_E : process (D_ROW)

begin

        for J in 0 to 7 loop

                E_ROW(J) <= D_ROW(J);

        end loop;

        for J in 8 to 15 loop

                E_ROW(J) <= D_ROW(7) or D_ROW(J);

        end loop;

end process GEN_E;

DOUT <= not(DIN(0) & (DIN(1 to 15) and not(E_ROW(0 to 14))));

FULL_OR <= E_ROW(15);

end DOWN; -- end of architecture