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

--  This file is a part of the LEON VHDL model

--  Copyright (C) 2003  Gaisler Research, all rights reserved

--

--  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 of the License, or (at your option) any later version.

--

--  See the file COPYING.LGPL for the full details of the license.

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

-- Konrad Eisele<eiselekd@web.de> ,2002  

library ieee;

use ieee.std_logic_1164.all;

use work.leon_config.all;

use work.leon_iface.all;

use work.mmuconfig.all;

entity mmutw is

  port (

    rst     : in  std_logic;

    clk     : in  std_logic;

    mmctrl1 : in  mmctrl_type1;

    twi     : in  mmutw_in_type;

    two     : out mmutw_out_type;

    mcmmo   : in  memory_mm_out_type;

    mcmmi   : out memory_mm_in_type

    );

end mmutw;

architecture rtl of mmutw is

  type write_buffer_type is record                      -- write buffer 

    addr, data  : std_logic_vector(31 downto 0);

    read        : std_logic;

  end record;

  type states is (idle, waitm, pte, lv1, lv2, lv3, lv4);

  type tw_rtype is record

    state       : states;

    wb          : write_buffer_type;

    req         : std_logic;

    walk_op     : std_logic;

    --#dump

    -- pragma translate_off

    finish      : std_logic;

    index       : std_logic_vector(31-2 downto 0);

    lvl         : std_logic_vector(1 downto 0);

    fault_mexc  : std_logic;

    fault_trans : std_logic;

    fault_lvl   : std_logic_vector(1 downto 0);

    pte,ptd,inv,rvd : std_logic;

    goon, found : std_logic;

    base        : std_logic_vector(31 downto 0);

    -- pragma translate_on

  end record;

  signal c,r : tw_rtype;

begin

  p0: process (clk, rst, r, c, twi, mcmmo, mmctrl1)

  variable v           : tw_rtype;

  variable finish      : std_logic;

  variable index       : std_logic_vector(31-2 downto 0);

  variable lvl         : std_logic_vector(1 downto 0);

  variable fault_mexc  : std_logic;

  variable fault_trans : std_logic;

  variable fault_inv   : std_logic;

  variable fault_lvl   : std_logic_vector(1 downto 0);

  variable pte,ptd,inv,rvd : std_logic;

  variable goon, found : std_logic;

  variable base        : std_logic_vector(31 downto 0);

  begin

    v := r;

    --#init

    finish := '0';

    index := (others => '0');

    lvl := (others => '0');

    fault_mexc := '0';

    fault_trans := '0';

    fault_inv := '0';

    fault_lvl := (others => '0');

    pte := '0';ptd := '0';inv := '0';rvd := '0';

    goon := '0'; found := '0';

    base := (others => '0');

    base(PADDR_PTD_U downto PADDR_PTD_D) := mcmmo.data(PTD_PTP32_U downto PTD_PTP32_D);

    if mcmmo.grant = '1' then

      v.req := '0';

    end if;

    -- # pte/ptd

    if ((mcmmo.ready and not r.req)= '1') then -- context

      case mcmmo.data(PT_ET_U downto PT_ET_D) is

        when ET_INV => inv := '1';

        when ET_PTD => ptd := '1'; goon := '1';

        when ET_PTE => pte := '1'; found := '1';

        when ET_RVD => rvd := '1'; null;

        when others => null;

      end case;

    end if;

    fault_trans := (rvd);

    fault_inv := inv;

    -- # state machine

    case r.state is

      when idle =>

        if (twi.walk_op_ur) = '1' then

          v.walk_op := '1';

          index(M_CTX_SZ-1 downto 0) := mmctrl1.ctx;

          base := (others => '0');

          base(PADDR_PTD_U downto PADDR_PTD_D) := mmctrl1.ctxp(MMCTRL_PTP32_U downto MMCTRL_PTP32_D);

          v.wb.addr := base or (index&"00");

          v.wb.read := '1';

          v.req := '1';

          v.state := lv1;

        elsif (twi.areq_ur) = '1' then

          index := (others => '0');

          v.wb.addr := twi.aaddr;

          v.wb.data := twi.adata;

          v.wb.read := '0';

          v.req := '1';

          v.state := waitm;

        end if;

      when waitm =>

        if ((mcmmo.ready and not r.req)= '1') then          -- amba: result ready current cycle

          fault_mexc := mcmmo.mexc;

          v.state := idle;

          finish := '1';

        end if;

      when lv1 =>

        if ((mcmmo.ready and not r.req)= '1') then

          lvl := LVL_CTX; fault_lvl := FS_L_CTX;

          index(VA_I1_SZ-1 downto 0) := twi.data(VA_I1_U downto VA_I1_D);

          v.state := lv2;

        end if;

      when lv2 =>

        if ((mcmmo.ready and not r.req)= '1') then

          lvl := LVL_REGION; fault_lvl :=  FS_L_L1;

          index(VA_I2_SZ-1 downto 0) := twi.data(VA_I2_U downto VA_I2_D);

          v.state := lv3;

        end if;

      when lv3 =>

        if ((mcmmo.ready and not r.req)= '1') then

          lvl := LVL_SEGMENT; fault_lvl := FS_L_L2;

          index(VA_I3_SZ-1 downto 0) := twi.data(VA_I3_U downto VA_I3_D);

          v.state := lv4;

        end if;

      when lv4 =>

        if ((mcmmo.ready and not r.req)= '1') then

          lvl := LVL_PAGE; fault_lvl := FS_L_L3;

          fault_trans := fault_trans or ptd;

          v.state := idle;

          finish := '1';

        end if;

      when others =>

        v.state := idle;

        finish := '0';

    end case;

    base := base or (index&"00");

    if r.walk_op = '1' then

      if (mcmmo.ready and (not r.req)) = '1' then

        fault_mexc := mcmmo.mexc;

        if (( ptd and

              (not fault_mexc ) and

              (not fault_trans) and

              (not fault_inv  )) = '1') then -- tw  : break table walk?

          v.wb.addr := base;

          v.req := '1';

        else

          v.walk_op := '0';

          finish := '1';

          v.state := idle;

        end if;

      end if;

    end if;

    -- # reset

    if ( rst = '0' ) then

      v.state := idle;

      v.req := '0';

    end if;

    --# drive signals

    two.finish      <= finish;

    two.data        <= mcmmo.data;

    two.addr        <= r.wb.addr(31 downto 0);

    two.lvl         <= lvl;

    two.fault_mexc  <= fault_mexc;

    two.fault_trans <= fault_trans;

    two.fault_inv   <= fault_inv;

    two.fault_lvl   <= fault_lvl;

    mcmmi.address  <= r.wb.addr;

    mcmmi.data     <= r.wb.data;

    mcmmi.burst    <= '0';

    mcmmi.size     <= "10";

    mcmmi.read     <= r.wb.read;

    mcmmi.lock     <= '0';

    mcmmi.req      <= r.req;

    --#dump

    -- pragma translate_off

    v.finish := finish;

    v.index := index;

    v.lvl   := lvl;

    v.fault_mexc := fault_mexc;

    v.fault_trans := fault_trans;

    v.fault_lvl := fault_lvl;

    v.pte   := pte;

    v.ptd   := ptd;

    v.inv   := inv;

    v.rvd   := rvd;

    v.goon  := goon;

    v.found := found;

    v.base  := base;

    -- pragma translate_on

    c <= v;

  end process p0;

  p1: process (clk)

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

  end process p1;

end rtl;