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;