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[/] [xmatchpro/] [trunk/] [xmw4-comdec/] [src/] [shift_byte.vhd] - Blame information for rev 9

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1 8 eejlny
--This library is free software; you can redistribute it and/or
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--modify it under the terms of the GNU Lesser General Public
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--License as published by the Free Software Foundation; either
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--version 2.1 of the License, or (at your option) any later version.
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--This library is distributed in the hope that it will be useful,
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--but WITHOUT ANY WARRANTY; without even the implied warranty of
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--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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--Lesser General Public License for more details.
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--You should have received a copy of the GNU Lesser General Public
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--License along with this library; if not, write to the Free Software
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--Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
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-- e_mail : j.l.nunez-yanez@byacom.co.uk
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---------------------------------
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--  ENTITY       = CAM_BIT     --
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--  version      = 1.0         --
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--  last update  = 30/05/98    --
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--  author       = Mark Gooch  --
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---------------------------------
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-- FUNCTION
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-- basic bit element of the CAM array
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-- reset to zero
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--  PIN LIST
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--  SEARCH   = input search data bit
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--  PREVIOUS = data from the previous location in the array
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--  MOVE     = movement control
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--  CLEAR    = asynchronous clear of the data latch (active LOW)
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--  CLK      = master clock
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--  RESET    = asynchronous reset of the data latch (active LOW)
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--  DOUT     = output of the data latch
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--  MATCH    = indicates a match between search bit and data bit (active LOW)
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library ieee;
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use ieee.std_logic_1164.all;
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entity CAM_BIT is
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port
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(
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        SEARCH : in bit;
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        PREVIOUS : in bit;
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        MOVE : in bit;
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        CLEAR : in bit ;
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        RESET : in bit;
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        CLK : in bit ;
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        DOUT : out bit;
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        MATCH : out bit
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);
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end CAM_BIT;
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-----------------------------------
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--  entity       = CAM_BIT       --
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--  ARCHITECTURE = BIT1          --
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--  version      = 1.0           --
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--  last update  = 30/05/95      --
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--  author       = Mark Gooch    --
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-----------------------------------
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architecture BIT1 of CAM_BIT is
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signal TEMP_D : bit;
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signal TEMP_Q : bit;
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begin
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COMB : process (TEMP_Q , PREVIOUS , MOVE)
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begin
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if (MOVE = '1') then
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                TEMP_D <= PREVIOUS;     -- get data from previous location
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else
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                TEMP_D <= TEMP_Q;       -- keep current data
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end if;
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--end if;
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end process COMB;
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LATCHES : process (CLK,CLEAR)
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begin
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if (CLEAR = '0') then
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        TEMP_Q <= '0';
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elsif ((CLK'event) and (CLK = '1')) then
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        if (RESET = '0') then
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                TEMP_Q <= '0';
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        else
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                TEMP_Q <= TEMP_D;
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        end if;
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end if;
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end process LATCHES;
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DOUT <= TEMP_Q;
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MATCH <= SEARCH xor TEMP_Q;             -- match goes low if SEARCH = TEMP_Q
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end BIT1;
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