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       = NFL_COUNTERS2  --

--  version      = 2.0            --

--  last update  = 08/08/01       --

--  author       = Jose Nunez     --

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

-- FUNCTION

-- synchronous counters to provide the next free location (NFL)

-- and next free location minus 1 (NFL_MINUS_ONE).

--  PIN LIST

--  INC           = synchronous increment of counters (active HIGH).

--  COUNT_ENABLE  = enable counting (active LOW).

--  CLK           = master clock.

--  RESET         = asynchronous reset of counters (active LOW).

--  NFL_MINUS_ONE = next free location minus one.

--  TABLE_FULL    = indicates that the table is full and the counters have been frozen

library ieee,dzx;

use ieee.std_logic_1164.all;

use dzx.bit_arith.all;

use dzx.attributes.all;

entity NFL_COUNTERS2 is

port

(

      INC : in bit ;

      COUNT_ENABLE : in bit ;

      CLK : in bit ;

      RESET : in bit ;

      CLEAR : in bit;

      NFL_MINUS_ONE : out bit_vector(7 downto 0) ;

      TABLE_FULL : out bit

);

end NFL_COUNTERS2;

architecture COUNT3 of NFL_COUNTERS2 is

signal TEMP_NFL_M_ONE : bit_vector(7 downto 0);

begin

COUNTERS : process ( CLK , CLEAR)

begin

-- CAM array starts with 1 valid locations 

if (CLEAR = '0') then

        TEMP_NFL_M_ONE <= "00000000";

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

                if( RESET = '0') then

                        TEMP_NFL_M_ONE <= "00000000";

                elsif ((INC = '1') and (COUNT_ENABLE = '0')) then            -- INC is full match active at one

                        if (TEMP_NFL_M_ONE = "00001111") then

                                TEMP_NFL_M_ONE <= TEMP_NFL_M_ONE;

                        else

                                TEMP_NFL_M_ONE <= TEMP_NFL_M_ONE + "00000001";

                        end if;

                end if;

end if;

end process COUNTERS;

TABLE_FULL <= '0' when TEMP_NFL_M_ONE = "00001111" else '1';

NFL_MINUS_ONE <= TEMP_NFL_M_ONE;

end COUNT3;