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       = POINTER_1        --
--  version      = 1.0              --
--  last update  = 9/05/00          --
--  author       = Jose Nunez       --
--------------------------------------
 
 
-- FUNCTION
-- first pointer
 
 
--  PIN LIST
--  PREVIOUS = data from the previous location in the pointer array
--  MOVE = select if load data or keep current data
--  CLEAR    = asynchronous clear of the data latches (active LOW)
--  CLK      = master clock
--  DOUT     = output of the data latches
 
 
 
library ieee;
use ieee.std_logic_1164.all;
 
entity POINTER_1 is
port
(
	PREVIOUS : in bit_vector(3 downto 0);
	MOVE : in bit;
	CLEAR : in bit ;
	RESET : in bit;
	CLK : in bit ;
	DOUT : out bit_vector(3 downto 0)
 
);
end POINTER_1;
 
architecture POINTER1 of POINTER_1 is
 
signal DOUT_AUX : bit_vector(3 downto 0);
 
 
begin
 
FLIP_FLOPS : process (CLK,CLEAR)
begin
     if (CLEAR = '0') then
	    DOUT_AUX <= "0001";
	  elsif ((CLK'event) and (CLK = '1')) then
	  	    if (RESET = '0') then
	    		DOUT_AUX <= "0001";
	  		elsif (MOVE = '1') then
	    		DOUT_AUX <= PREVIOUS;
			else
				DOUT_AUX <= DOUT_AUX;		
	        end if;
	end if;
end process FLIP_FLOPS;
 
DOUT <= DOUT_AUX;
 
end POINTER1;