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       = INPUT_COUNTER                   --

--  version      = 1.0                         --

--  last update  = 30/5/01                     --

--  author       = Jose Nunez                  --

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

-- FUNCTION

-- 8 bit counter for the read and write of the input buffer

--  PIN LIST

--  ENABLE = enable count 

--  CLEAR = asyncronus clear of the counter

--  CLEAR_COUNTERS : syncronous clear of counters

--  CLK   = master clock

--  COUNT = count output

library ieee,dzx;

use ieee.std_logic_1164.all;

use dzx.bit_arith.all;

use dzx.bit_utils.all;

entity INPUT_COUNTER_9BITS is

port (ENABLE : in bit;

          CLEAR : in bit;

          CLEAR_COUNTERS : in bit;

          CLK : in bit;

          COUNT : out bit_vector(8 downto 0)

     );

end INPUT_COUNTER_9BITS;

architecture STRUCTURAL of INPUT_COUNTER_9BITS is

signal COUNT_AUX : bit_vector(8 downto 0);

begin

COUNTING : process (CLK,CLEAR,ENABLE,CLEAR_COUNTERS)

begin

        -- asynchronous RESET signal forces all outputs LOW

      if (CLEAR = '0') then

            COUNT_AUX <= "000000000";

            -- check for +ve clock edge

          elsif ((CLK'event) and (CLK = '1')) then

                    if (CLEAR_COUNTERS = '1') then

                               COUNT_AUX <= "000000000";

                  elsif( ENABLE = '1') then

                           COUNT_AUX <= COUNT_AUX+"000000001";

                          else

                               COUNT_AUX <= COUNT_AUX;

                          end if;

         end if;

end process COUNTING;

COUNT <= COUNT_AUX;

end STRUCTURAL;