Subversion Repositories mips_enhanced

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

--  This file is a part of the GRLIB VHDL IP LIBRARY

--  Copyright (C) 2003, Gaisler Research

--

--  This program is free software; you can redistribute it and/or modify

--  it under the terms of the GNU General Public License as published by

--  the Free Software Foundation; either version 2 of the License, or

--  (at your option) any later version.

--

--  This program 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 General Public License for more details.

--

--  You should have received a copy of the GNU General Public License

--  along with this program; if not, write to the Free Software

--  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

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

-- Entity:      mmulrue

-- File:        mmulrue.vhd

-- Author:      Konrad Eisele, Jiri Gaisler, Gaisler Research

-- Description: MMU LRU logic

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

library ieee;

use ieee.std_logic_1164.all;

library grlib;

use grlib.amba.all;

use grlib.stdlib.all;

library gaisler;

use gaisler.libiu.all;

use gaisler.libcache.all;

use gaisler.leon3.all;

use gaisler.mmuconfig.all;

use gaisler.mmuiface.all;

entity mmulrue is

  generic (

    position : integer;

    entries  : integer := 8 );

  port (

    rst    : in std_logic;

    clk    : in std_logic;

    lruei  : in mmulrue_in_type;

    lrueo  : out mmulrue_out_type );

end mmulrue;

architecture rtl of mmulrue is

  constant entries_log : integer := log2(entries);

  type lru_rtype is record

    pos      : std_logic_vector(entries_log-1 downto 0);

    movetop  : std_logic;

    -- pragma translate_off

    dummy  : std_logic;

    -- pragma translate_on

  end record;

  signal c,r   : lru_rtype;

begin

  p0: process (rst, r, c, lruei)

    variable v : lru_rtype;

    variable ov : mmulrue_out_type;

  begin

    v := r; ov := mmulrue_out_none;

    -- #init

    if (r.movetop) = '1' then

      if (lruei.fromleft) = '0' then

        v.pos := lruei.left(entries_log-1 downto 0);

        v.movetop := '0';

      end if;

    elsif (lruei.fromright) = '1' then

      v.pos := lruei.right(entries_log-1 downto 0);

      v.movetop := not lruei.clear;

    end if;

    if (lruei.touch and not lruei.clear) = '1' then  -- touch request

      if (v.pos = lruei.pos(entries_log-1 downto 0)) then     -- check

          v.movetop := '1';

      end if;

    end if;

    if ((rst) = '0') or (lruei.flush = '1') then

      v.pos := conv_std_logic_vector(position, entries_log);

      v.movetop := '0';

    end if;

    --# Drive signals

    ov.pos(entries_log-1 downto 0) := r.pos;

    ov.movetop := r.movetop;

    lrueo <= ov;

    c <= v;

  end process p0;

  p1: process (clk)

  begin if rising_edge(clk) then r <= c; end if;

  end process p1;

end rtl;