Subversion Repositories core_arm

 
 
 
 
----------------------------------------------------------------------------
--  This file is a part of the LEON VHDL model
--  Copyright (C) 1999  European Space Agency (ESA)
--
--  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.
 
 
-----------------------------------------------------------------------------
-- Entity: 	mctrl
-- File:	mctrl.vhd
-- Author:	Jiri Gaisler - ESA/ESTEC
-- Description:	External memory controller.
------------------------------------------------------------------------------
 
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned."+";
use IEEE.std_logic_unsigned."-";
use IEEE.std_logic_unsigned.conv_integer;
use IEEE.std_logic_arith.conv_unsigned;
use work.peri_mem_config.all;
use work.peri_mem_comp.all;
use work.peri_io_comp.all;
use work.tech_map.all;
use work.macro.all;
use work.amba.all;
 
entity mctrl is
  port (
    rst    : in  std_logic;
    clk    : in  std_logic;
    memi   : in  memory_in_type;
    memo   : out memory_out_type;
    ahbsi  : in  ahb_slv_in_type;
    ahbso  : out ahb_slv_out_type;
    apbi   : in  apb_slv_in_type;
    apbo   : out apb_slv_out_type;
    pioo   : in  pio_out_type;
    wpo    : in  wprot_out_type;
    sdo    : out sdram_out_type;
    mctrlo : out mctrl_out_type
  );
end; 
 
architecture rtl of mctrl is
 
 
type areatype is (rom, io, ram);
type memcycletype is (idle, berr, bread, bwrite, bread8, bwrite8, bread16, bwrite16);
 
 
-- memory configuration register 1 type
 
type mcfg1type is record
  romrws           : std_logic_vector(3 downto 0);
  romwws           : std_logic_vector(3 downto 0);
  romwidth         : std_logic_vector(1 downto 0);
  romwrite         : std_logic;
 
  ioen             : std_logic;
  iows             : std_logic_vector(3 downto 0);
  bexcen           : std_logic;
  brdyen           : std_logic;
  iowidth          : std_logic_vector(1 downto 0);
end record;
 
-- memory configuration register 2 type
 
type mcfg2type is record
  ramrws           : std_logic_vector(1 downto 0);
  ramwws           : std_logic_vector(1 downto 0);
  ramwidth         : std_logic_vector(1 downto 0);
  rambanksz        : std_logic_vector(3 downto 0);
  rmw              : std_logic;
  brdyen           : std_logic;
  srdis            : std_logic;
  sdren            : std_logic;
end record;
 
-- memory status register type
 
 
 
-- local registers
 
type reg_type is record
  address          : std_logic_vector(31 downto 0);  -- memory address
  data             : std_logic_vector(31 downto 0);  -- latched memory data
  writedata        : std_logic_vector(31 downto 0);
  writedata8       : std_logic_vector(15 downto 0);  -- lsb write data buffer
  readdata         : std_logic_vector(31 downto 0);
  brdyn            : std_logic;
  ready            : std_logic;
  ready8           : std_logic;
  bdrive           : std_logic_vector(3 downto 0);
  ws               : std_logic_vector(3 downto 0);
  romsn		   : std_logic_vector(1 downto 0);
  ramsn		   : std_logic_vector(4 downto 0);
  ramoen	   : std_logic_vector(4 downto 0);
  size		   : std_logic_vector(1 downto 0);
  busw		   : std_logic_vector(1 downto 0);
  psel		   : std_logic_vector(1 downto 0);
  oen              : std_logic;
  iosn		   : std_logic_vector(1 downto 0);
  read             : std_logic;
  wrn              : std_logic_vector(3 downto 0);
  writen           : std_logic;
  bstate           : memcycletype;
  area  	   : areatype;
  mcfg1		   : mcfg1type;
  mcfg2		   : mcfg2type;
  bexcn            : std_logic;		-- latched external bexcn
  echeck           : std_logic;
  brmw             : std_logic;
  haddr            : std_logic_vector(31 downto 0);
  hsel             : std_logic;
  srhsel           : std_logic;
  hwrite           : std_logic;
  hburst           : std_logic_vector(2 downto 0);
  htrans           : std_logic_vector(1 downto 0);
  hresp 	   : std_logic_vector(1 downto 0);
end record;
 
component sdmctrl
  port (
    rst    : in  std_logic;
    clk    : in  std_logic;
    sdi    : in  sdram_in_type;
    sdo    : out sdram_out_type;
    apbi   : in  apb_slv_in_type;
    apbo   : out apb_slv_out_type;
    wpo    : in  wprot_out_type;
    sdmo   : out sdram_mctrl_out_type
  );
end component; 
 
 
signal r, ri : reg_type;
signal wrnout : std_logic_vector(3 downto 0);
signal promdata : std_logic_vector(31 downto 0); -- data from boot-prom
signal sdmo : sdram_mctrl_out_type;
signal sdi  : sdram_in_type;
signal sdapbo   :  apb_slv_out_type;
 
begin
 
  ctrl : process(rst, ahbsi, apbi, memi, r, pioo, promdata, wpo, sdmo
 
		)
  variable v : reg_type;		-- local variables for registers
  variable start : std_logic;
  variable dataout : std_logic_vector(31 downto 0); -- data from memory
  variable regsd : std_logic_vector(31 downto 0);   -- data from registers
  variable memdata : std_logic_vector(31 downto 0);   -- data to memory
  variable rws : std_logic_vector(3 downto 0);		-- read waitstates
  variable wws : std_logic_vector(3 downto 0);		-- write waitstates
  variable wsnew : std_logic_vector(3 downto 0);		-- write waitstates
  variable adec : std_logic_vector(1 downto 0);
  variable rams : std_logic_vector(4 downto 0);
  variable bready, leadin : std_logic;
  variable csen : std_logic;			-- Generate chip selects
  variable aprot   : std_logic_vector(14 downto 0); -- 
  variable wrn   : std_logic_vector(3 downto 0); -- 
  variable bexc, addrerr : std_logic;
  variable ready : std_logic;
  variable writedata : std_logic_vector(31 downto 0);
  variable bwdata : std_logic_vector(31 downto 0);
  variable merrtype  : std_logic_vector(2 downto 0); -- memory error type
  variable noerror : std_logic;
  variable area  : areatype;
  variable bdrive : std_logic_vector(3 downto 0);
  variable ramsn : std_logic_vector(4 downto 0);
  variable romsn, busw : std_logic_vector(1 downto 0);
  variable iosn : std_logic;
  variable lock : std_logic;
  variable wprothitx : std_logic;
  variable brmw : std_logic;
  variable bpsel : std_logic;
  variable psel : std_logic;
  variable bidle: std_logic;
  variable haddr   : std_logic_vector(31 downto 0);
  variable hsize   : std_logic_vector(1 downto 0);
  variable hwrite  : std_logic;
  variable hburst  : std_logic_vector(2 downto 0);
  variable htrans  : std_logic_vector(1 downto 0);
  variable sdhsel, srhsel, hready  : std_logic;
 
  begin
 
-- Variable default settings to avoid latches
 
    v := r; wprothitx := '0'; v.ready8 := '0'; v.iosn(0) := r.iosn(1);
 
    ready := '0'; addrerr := '0'; regsd := (others => '0'); csen := '0';
 
    v.ready := '0'; v.echeck := '0'; bpsel := '0';
    merrtype := "---"; bready := '1';
 
    v.data := memi.data; v.bexcn := memi.bexcn; v.brdyn := memi.brdyn;
    if (((r.brdyn and r.mcfg1.brdyen) = '1') and (r.area = io)) or
       (((r.brdyn and r.mcfg2.brdyen) = '1') and (r.area = ram) and
	 (r.ramsn(4) = '0') and CFG_PERIMEM_RAMSEL5)
    then
      bready := '0';
    else bready := '1'; end if;
 
    v.hresp := HRESP_OKAY;
 
 
 
    if CFG_PERIMEM_SDRAMEN and (r.hsel = '1') and (ahbsi.hready = '0') then 
      haddr := r.haddr;  hsize := r.size; hburst := r.hburst;
      htrans := r.htrans; hwrite := r.hwrite;
    else 
      haddr := ahbsi.haddr;  hsize := ahbsi.hsize(1 downto 0); 
      hburst := ahbsi.hburst; htrans := ahbsi.htrans; hwrite := ahbsi.hwrite;
    end if;
 
    if CFG_PERIMEM_SDRAMEN then
      sdhsel := ahbsi.hsel and r.mcfg2.sdren and ahbsi.haddr(30) and
		(ahbsi.haddr(29) or r.mcfg2.srdis);
      srhsel := ahbsi.hsel and not sdhsel;
    else sdhsel := '0'; srhsel := ahbsi.hsel; end if;
 
-- decode memory area parameters
 
    case haddr(30 downto 28) is
    when "000" | "001" => area := rom;
    when "010" | "011" => area := io;
    when others => area := ram;
    end case;
 
    leadin := '0'; rws := "----"; wws := "----"; adec := "--";
    busw := (others => '-'); brmw := '0';
    case area is
    when rom => 
      busw := r.mcfg1.romwidth;
    when ram => 
      adec := genmux(r.mcfg2.rambanksz, haddr(29 downto 14)) &
              genmux(r.mcfg2.rambanksz, haddr(28 downto 13));
 
      if sdhsel = '1' then busw := "10";
 
      else
        busw := r.mcfg2.ramwidth;
        if ((r.mcfg2.rmw and ahbsi.hwrite) = '1') and 
	 ((CFG_PERIMEM_BUS16EN and (busw = "01") and (hsize = "00")) or
	  ((busw(1) = '1') and (hsize(1) = '0'))
 
        )
        then brmw := '1'; end if;	 -- do a read-modify-write cycle
      end if;
    when io =>
      leadin := '1';
      busw := r.mcfg1.iowidth;
    when others =>
    end case;
 
-- decode waitstates, illegal access and cacheability
 
    case r.area is
    when rom =>
      rws := r.mcfg1.romrws; wws := r.mcfg1.romwws;
      if (r.mcfg1.romwrite or r.read) = '0' then addrerr := '1'; end if;
    when ram =>
      rws := "00" & r.mcfg2.ramrws; wws := "00" & r.mcfg2.ramwws;
    when io =>
      rws := r.mcfg1.iows; wws := r.mcfg1.iows;
      if r.mcfg1.ioen = '0' then addrerr := '1'; end if;
    when others => null;
    end case;
 
-- generate data buffer enables
 
    bdrive := (others => '1');
    case r.busw is
    when "00" => if CFG_PERIMEM_BUS8EN then bdrive := "0001"; end if;
    when "01" => if CFG_PERIMEM_BUS16EN then bdrive := "0011"; end if;
    when others =>
    end case;
 
-- generate chip select and output enable
 
    rams := '0' & decode(adec);
    if CFG_PERIMEM_RAMSEL5 then 
      if haddr(29) = '1' then rams := "10000"; end if;
    end if;
 
    iosn := '1'; ramsn := (others => '1'); romsn := (others => '1');
    psel := '1'; v.psel(1) := r.psel(0);
    case area is
    when rom => 
      if ((CFG_PERIMEM_BOOT = perimem_memory) or ((CFG_PERIMEM_BOOT = perimem_dual) and (pioo.io8lsb(4) = '0'))) then
	romsn(0) := haddr(28); 
      else psel := haddr(28); end if;
      romsn(1) := not haddr(28);
    when ram => ramsn := not rams;
    when io => iosn := '0'; 
    when others => null;
    end case;
 
-- generate write strobe
 
    wrn := "0000";
    case r.busw is
    when "00" => 
      if CFG_PERIMEM_BUS8EN then wrn := "1110"; end if;
    when "01" => 
      if CFG_PERIMEM_BUS16EN then
	if (r.size = "00") and (r.brmw = '0') then
	  wrn := "11" & (not r.address(0)) & r.address(0);
        else wrn := "1100"; end if;
      end if;
    when "10" | "11" =>
      case r.size is
      when "00" => 
        case r.address(1 downto 0) is
        when "00" => wrn := "1110";
        when "01" => wrn := "1101";
        when "10" => wrn := "1011";
        when others => wrn := "0111";
        end case;
      when "01" => 
        wrn := not r.address(1) & not r.address(1) & r.address(1) & r.address(1);
      when others => null;
      end case;
    when others => null;
    end case;
 
    if (r.mcfg2.rmw = '1') and (r.area = ram) then wrn := not bdrive; end if;
 
    if (((ahbsi.hready and ahbsi.hsel) = '1') or (((sdmo.aload and r.hsel) = '1') and CFG_PERIMEM_SDRAMEN))
    then
      v.area := area;
      v.address  := haddr; v.psel(0) := psel;
      if (busw = "00") and (hwrite = '0') and (area /= io) and CFG_PERIMEM_BUS8EN
      then v.address(1 downto 0) := "00"; end if;
      if (busw = "01") and (hwrite = '0') and (area /= io) and CFG_PERIMEM_BUS16EN
      then v.address(1 downto 0) := "00"; end if;
      if (brmw = '1') then 
	v.read := '1'; 
 
      else v.read := not hwrite; end if;
      v.busw := busw; v.brmw := brmw;
 
    end if;
 
-- Select read data depending on bus width
 
    if CFG_PERIMEM_BUS8EN and (r.busw = "00") then 
      memdata := r.readdata(23 downto 0) & r.data(31 downto 24);
    elsif CFG_PERIMEM_BUS16EN and (r.busw = "01") then 
      memdata := r.readdata(15 downto 0) & r.data(31 downto 16);
    else 
      memdata := r.data;
    end if;
 
    bwdata := memdata;
 
-- Merge data during byte write
 
    writedata := ahbsi.hwdata;
    if ((r.brmw and r.busw(1)) = '1')
 
    then
      case r.address(1 downto 0) is
 
      when "00" => 
	writedata(15 downto 0) := bwdata(15 downto 0);
	if r.size = "00" then 
	  writedata(23 downto 16) := bwdata(23 downto 16);
	end if;
      when "01" => 
	writedata(31 downto 24) := bwdata(31 downto 24);
	writedata(15 downto 0) := bwdata(15 downto 0);
      when "10" => 
	writedata(31 downto 16) := bwdata(31 downto 16);
	if r.size = "00" then 
	  writedata(7 downto 0) := bwdata(7 downto 0);
	end if;
      when  others => 
	writedata(31 downto 8) := bwdata(31 downto 8);
      end case;
    end if;
    if (r.brmw = '1') and (r.busw = "01") and CFG_PERIMEM_BUS16EN then
      if (r.address(0) = '0') then 
        writedata(23 downto 16) :=  r.data(23 downto 16);
      else
        writedata(31 downto 24) :=  r.data(31 downto 24);
      end if;
    end if;
 
-- save read data during 8/16 bit reads
 
    if CFG_PERIMEM_BUS8EN and (r.ready8 = '1') and (r.busw = "00") then
      v.readdata := v.readdata(23 downto 0) & r.data(31 downto 24);
    elsif CFG_PERIMEM_BUS16EN and (r.ready8 = '1') and (r.busw = "01") then
      v.readdata := v.readdata(15 downto 0) & r.data(31 downto 16);
    end if;
 
-- Ram, rom, IO access FSM
 
    if r.read = '1' then wsnew := rws; else wsnew := wws; end if;
 
    case r.bstate is
    when idle =>
      v.ws := wsnew; 
 
      if r.bdrive(0) = '1' then 
 
        if r.busw(1) = '1' then v.writedata := writedata;
	else
	  v.writedata(31 downto 16) := writedata(31 downto 16);
	  v.writedata8 := writedata(15 downto 0);
	end if;
 
      end if;
      if (r.srhsel = '1') and ((sdmo.busy = '0') or not CFG_PERIMEM_SDRAMEN)
 
      then
        if CFG_PERIMEM_WPROTEN then wprothitx := wpo.wprothit; end if;
	if (wprothitx or addrerr) = '1' then
	  v.hresp := HRESP_ERROR; v.bstate := berr; v.bdrive := (others => '1');
	elsif r.read = '0' then 
	  if (r.busw = "00") and (r.area /= io) and CFG_PERIMEM_BUS8EN then 
	    v.bstate := bwrite8;
	  elsif (r.busw = "01") and (r.area /= io) and CFG_PERIMEM_BUS16EN then 
	    v.bstate := bwrite16;
   	  else v.bstate := bwrite; end if;
	  v.wrn := wrn; v.writen := '0'; v.bdrive := not bdrive;
	else 
	  if r.oen = '1' then v.ramoen := r.ramsn; v.oen := '0';
	  else
	    if (r.busw = "00") and (r.area /= io) and CFG_PERIMEM_BUS8EN then v.bstate := bread8;
	    elsif (r.busw = "01") and (r.area /= io) and CFG_PERIMEM_BUS16EN then v.bstate := bread16;
	    else v.bstate := bread; end if;
	  end if;
	end if;
      end if;
    when berr =>
      v.bstate := idle; ready := '1';
      v.hresp := HRESP_ERROR;
      v.ramsn := (others => '1'); v.romsn := (others => '1'); v.psel(0) := '1';
      v.ramoen := (others => '1'); v.oen := '1'; v.iosn := "11"; v.bdrive := (others => '1');
    when bread => 
      if ((r.ws = "0000") and (r.ready = '0') and (bready = '1'))
      then 
	if r.brmw = '0' then
	  ready := '1'; v.address := ahbsi.haddr; v.echeck := '1';
	end if;
        if (((ahbsi.hsel = '0') or (ahbsi.htrans /= HTRANS_SEQ)) or (r.hburst = HBURST_SINGLE))
        then
  	  v.ramoen := (others => '1'); v.oen := '1'; v.iosn := "11";
   	  v.bstate := idle; v.read := not r.hwrite;
	  if r.brmw = '0' then
  	    v.ramsn := (others => '1'); v.romsn := (others => '1'); 
	    v.psel(0) := '1';
	  else 
	    v.echeck := '1'; 
	  end if;
	end if;
      end if;
      if r.ready = '1' then
	v.ws := rws;
      else
	if r.ws /= "0000" then v.ws := r.ws - 1; end if;
      end if;
    when bwrite =>
      if (r.ws = "0000") and (bready = '1') then
	ready := '1'; v.wrn := (others => '1'); v.writen := '1'; v.echeck := '1';
	v.ramsn := (others => '1'); v.romsn := (others => '1'); v.iosn := "11";
	v.bdrive := (others => '1'); v.bstate := idle;
	v.psel(0) := '1';
      end if;
      if r.ws /= "0000" then v.ws := r.ws - 1; end if;
    when bread8 => 
      if CFG_PERIMEM_BUS8EN then
        if (r.ws = "0000") and (r.ready8 = '0') then
	  v.ready8 := '1'; v.ws := rws; 
	  v.address(1 downto 0) := r.address(1 downto 0) + 1;
 
          if (r.address(1 downto 0) = "11") then
	    ready := '1'; v.address := ahbsi.haddr; v.echeck := '1';
 
            if (((ahbsi.hsel = '0') or (ahbsi.htrans /= HTRANS_SEQ)) or 
	        (r.hburst = HBURST_SINGLE))
            then
  	      v.ramoen := (others => '1'); v.oen := '1'; v.iosn := "11";
   	      v.bstate := idle;
 
  	      v.ramsn := (others => '1'); v.romsn := (others => '1');
	      v.psel(0) := '1';
 
	    end if;
          end if;
        end if;
        if (r.ready8 = '1') then v.ws := rws;
        elsif r.ws /= "0000" then v.ws := r.ws - 1; end if;
      else
	v.bstate := idle;
      end if;
    when bwrite8 =>
      if CFG_PERIMEM_BUS8EN then
        if (r.ws = "0000") and (r.ready8 = '0') then 
	  v.ready8 := '1'; v.wrn := (others => '1'); v.writen := '1';
        end if;
 
        if (r.ws = "0000") and 
           ((r.address(1 downto 0) = "11") or 
            ((r.address(1 downto 0) = "01") and (r.size = "01")) or
	    (r.size = "00")) 
 
        then
	  ready := '1'; v.wrn := (others => '1'); v.writen := '1'; v.echeck := '1';
	  v.ramsn := (others => '1'); v.romsn := (others => '1'); v.iosn := "11";
	  v.bdrive := (others => '1'); v.bstate := idle;
	  v.psel(0) := '1';
 
        end if;
        if (r.ready8 = '1') then
	  v.address(1 downto 0) := r.address(1 downto 0) + 1; v.ws := rws; 
--	  v.writedata(31 downto 8) := r.writedata(23 downto 0);
	  v.writedata(31 downto 16) := r.writedata(23 downto 16) & r.writedata8(15 downto 8);
	  v.writedata8(15 downto 8) := r.writedata8(7 downto 0);
	  v.bstate := idle; 
 
        end if;
        if r.ws /= "0000" then v.ws := r.ws - 1; end if;
      else
	v.bstate := idle;
      end if;
    when bread16 => 
      if CFG_PERIMEM_BUS16EN then
        if (r.ws = "0000") and ((r.address(1) or r.brmw) = '1') and 
	   (r.ready8 = '0') 
        then
	  if r.brmw = '0' then
	    ready := '1'; v.address := ahbsi.haddr; v.echeck := '1';
	  end if;
          if (((ahbsi.hsel = '0') or (ahbsi.htrans /= HTRANS_SEQ)) or 
	      (r.hburst = HBURST_SINGLE))
          then
	    if r.brmw = '0' then
  	      v.ramsn := (others => '1'); v.romsn := (others => '1');
	      v.psel(0) := '1';
	    end if;
  	    v.ramoen := (others => '1'); v.oen := '1'; v.iosn := "11";
   	    v.bstate := idle; v.read := not r.hwrite;
	  end if;
        end if;
        if (r.ws = "0000") and (r.ready8 = '0') then 
	  v.ready8 := '1'; v.ws := rws; 
	  if r.brmw = '0' then v.address(1) := not r.address(1); end if;
        end if;
        if r.ws /= "0000" then v.ws := r.ws - 1; end if;
      else
	v.bstate := idle;
      end if;
    when bwrite16 =>
      if CFG_PERIMEM_BUS16EN then
        if (r.ws = "0000") and 
           ((r.address(1 downto 0) = "10") or (r.size(1) = '0')) 
        then
	  ready := '1'; v.wrn := (others => '1'); v.writen := '1'; v.echeck := '1';
	  v.ramsn := (others => '1'); v.romsn := (others => '1'); v.iosn := "11";
	  v.bdrive := (others => '1'); v.bstate := idle;
	  v.psel(0) := '1';
        end if;
        if (r.ws = "0000") and (r.ready8 = '0') then 
	  v.ready8 := '1'; v.wrn := (others => '1'); v.writen := '1';
        end if;
        if (r.ready8 = '1') then
	  v.address(1) := not r.address(1); v.ws := rws; 
	  v.writedata(31 downto 16) := r.writedata8(15 downto 0);
	  v.bstate := idle; 
        end if;
        if r.ws /= "0000" then v.ws := r.ws - 1; end if;
      else
	v.bstate := idle;
      end if;
    when others =>
    end case;
 
-- if BUSY or IDLE cycle seen, or if de-selected, return to idle state
    if (ahbsi.hready = '1') then
      if ((ahbsi.hsel = '0') or (ahbsi.htrans = HTRANS_BUSY) or 
	(ahbsi.htrans = HTRANS_IDLE))
      then
        v.bstate := idle;
        v.ramsn := (others => '1'); v.romsn := (others => '1');
        v.ramoen := (others => '1'); v.oen := '1'; v.iosn := "11";
        v.bdrive := (others => '1'); v.wrn := (others => '1');
        v.writen := '1'; v.hsel := '0'; ready := ahbsi.hsel; v.srhsel := '0';
	v.psel(0) := '1';
      elsif srhsel = '1' then
        v.romsn := romsn; v.ramsn(4 downto 0) := ramsn(4 downto 0); v.iosn := iosn & '1';
        v.psel(0) := psel;
        if v.read = '1' then v.ramoen(4 downto 0) := ramsn(4 downto 0); v.oen := leadin; end if;
      end if;
    end if;
 
-- error checking and reporting
 
    noerror := '1';
    if ((r.echeck and r.mcfg1.bexcen and not r.bexcn) = '1') then
      noerror := '0'; v.bstate := berr; v.hresp := HRESP_ERROR; v.bdrive := (others => '1');
    end if;
 
-- APB register access
 
    case apbi.paddr(3 downto 2) is
    when "00" => 
      regsd(28 downto 0) := r.mcfg1.iowidth & 
	r.mcfg1.brdyen & r.mcfg1.bexcen & "0" & r.mcfg1.iows & r.mcfg1.ioen &
	'0' & 
 
	"000000" & r.mcfg1.romwrite & 
 
	'0' & r.mcfg1.romwidth & r.mcfg1.romwws & r.mcfg1.romrws;
    when "01" => 
      if CFG_PERIMEM_SDRAMEN then
	regsd(31 downto 19) := sdapbo.prdata(31 downto 19);
        regsd(14 downto 13) := r.mcfg2.sdren & r.mcfg2.srdis;
      end if;
      regsd(12 downto 9) := r.mcfg2.rambanksz;
      if CFG_PERIMEM_RAMSEL5 then regsd(7) := r.mcfg2.brdyen; end if;
      regsd(6 downto 0) := r.mcfg2.rmw & r.mcfg2.ramwidth & 
	r.mcfg2.ramwws & r.mcfg2.ramrws;
    when "10" => 
 
      if CFG_PERIMEM_SDRAMEN then
	regsd(26 downto 12) := sdapbo.prdata(26 downto 12);
      end if;
    when others => regsd := (others => '0');
    end case;
 
    apbo.prdata <= regsd;
 
    if (apbi.psel and apbi.penable and apbi.pwrite) = '1' then
      case apbi.paddr(5 downto 2) is
      when "0000" => 
        v.mcfg1.romrws      :=  apbi.pwdata(3 downto 0); 
        v.mcfg1.romwws      :=  apbi.pwdata(7 downto 4);
        v.mcfg1.romwidth    :=  apbi.pwdata(9 downto 8);
        v.mcfg1.romwrite    :=  apbi.pwdata(11);
 
        v.mcfg1.ioen        :=  apbi.pwdata(19);
        v.mcfg1.iows        :=  apbi.pwdata(23 downto 20);
        v.mcfg1.bexcen      :=  apbi.pwdata(25);
        v.mcfg1.brdyen      :=  apbi.pwdata(26);
        v.mcfg1.iowidth     :=  apbi.pwdata(28 downto 27);
      when "0001" => 
        v.mcfg2.ramrws      := apbi.pwdata(1 downto 0);
        v.mcfg2.ramwws      := apbi.pwdata(3 downto 2);
        v.mcfg2.ramwidth    := apbi.pwdata(5 downto 4);
        v.mcfg2.rmw         := apbi.pwdata(6);
        v.mcfg2.brdyen      := apbi.pwdata(7);
        v.mcfg2.rambanksz   := apbi.pwdata(12 downto 9);
	if CFG_PERIMEM_SDRAMEN then
          v.mcfg2.srdis       := apbi.pwdata(13);
          v.mcfg2.sdren       := apbi.pwdata(14);
	end if;
 
      when others => null;
      end case;
    end if;
 
-- select appropriate data during reads
 
    case r.area is
    when rom | ram => 
      dataout := memdata;
      if (r.area = rom) and (CFG_PERIMEM_BOOT /= perimem_memory) then
	if (r.psel(0) = '0') then v.readdata := promdata; end if;
        if r.psel(1) = '0' then dataout := r.readdata; end if;
      end if;
    when others =>
      if CFG_PERIMEM_BUS8EN and (r.busw = "00") then
        dataout := r.data(31 downto 24) & r.data(31 downto 24) 
		 & r.data(31 downto 24) & r.data(31 downto 24);
      elsif CFG_PERIMEM_BUS16EN and (r.busw = "01") then
        dataout := r.data(31 downto 16) & r.data(31 downto 16); 
      else dataout := r.data; end if;
    end case;
 
 
    v.ready := ready;
    v.srhsel := r.srhsel and not ready;
    if ahbsi.hready = '1' then v.hsel := ahbsi.hsel; end if;
 
    if ((ahbsi.hready and ahbsi.hsel) = '1') then
      v.size := ahbsi.hsize(1 downto 0); v.hwrite := ahbsi.hwrite;
      v.hburst := ahbsi.hburst; v.htrans := ahbsi.htrans;
      if ahbsi.htrans(1) = '1' then v.hsel := '1'; v.srhsel := srhsel; end if;
      if CFG_PERIMEM_SDRAMEN then 
	v.haddr := ahbsi.haddr;
      end if;
    end if;
 
-- sdram synchronisation
 
    if CFG_PERIMEM_SDRAMEN then
      if (r.bstate /= idle) then bidle := '0';
      else
        bidle := '1';
        if (sdmo.busy and not sdmo.aload) = '1' then 
	  v.address(16 downto 2) := sdmo.address;
	  v.romsn := (others => '1'); v.ramsn(4 downto 0) := (others => '1'); 
	  v.iosn := (others =>'1'); v.ramoen(4 downto 0) := (others => '1'); 
	  v.oen := '1';
          v.bdrive := not (sdmo.bdrive & sdmo.bdrive & sdmo.bdrive & sdmo.bdrive);
	  v.hresp := sdmo.hresp;
        end if;
      end if;
      if (sdmo.aload and r.srhsel) = '1' then
        v.romsn := romsn; v.ramsn(4 downto 0) := ramsn(4 downto 0); v.iosn := iosn & '1';
        v.psel(0) := psel;
        if v.read = '1' then v.ramoen(4 downto 0) := ramsn(4 downto 0); v.oen := leadin; end if;
      end if;
      if sdmo.hsel = '1' then 
	v.writedata := writedata;
	hready := sdmo.hready and noerror and not r.brmw;
 
      else hready := r.ready and noerror; end if;
    else
      hready := r.ready and noerror;
    end if;
 
-- use d(15:0) as I/O ports (only usefull in 8/16-bit mode)
 
    if (CFG_PERIMEM_BUS8EN or CFG_PERIMEM_BUS16EN) then 
      mctrlo.pioh <= r.data(15 downto 0);
      if ((r.mcfg1.romwidth(1) or r.mcfg1.iowidth(1) or r.mcfg2.ramwidth(1)) = '0')
	 and ((r.mcfg2.sdren = '0') or not CFG_PERIMEM_SDRAMEN)
      then
        v.writedata(15 downto 0) := r.writedata(15 downto 0);
        if pioo.wrio = '1' then 
	  v.writedata(15 downto 0) := pioo.piol(31 downto 16);
        end if;
        v.wrn(3 downto 2) := "11";
	v.bdrive(3 downto 2) := pioo.piodir(17 downto 16);
      end if;
    else mctrlo.pioh <= (others => '0'); end if;
 
-- reset
 
    if rst = '0' then
 
      v.bstate 	 	   := idle; 
      v.read 		   := '1'; 
      v.wrn                := "1111";
      v.writen		   := '1'; 
      v.mcfg1.romwrite     := '0';
      v.mcfg1.ioen         := '0';
      v.mcfg1.brdyen       := '0';
      v.mcfg1.bexcen       := '0';
      v.hsel		   := '0';
      v.srhsel		   := '0';
      if ((CFG_PERIMEM_BOOT = perimem_memory) or ((CFG_PERIMEM_BOOT = perimem_dual) and (pioo.io8lsb(4) = '0'))) 
      then
        v.mcfg1.romrws     := "1111";
        v.mcfg1.romwws     := "1111";
        v.mcfg1.romwidth   := pioo.io8lsb(1 downto 0);
      else
	v.mcfg2.ramrws	   := std_logic_vector(CFG_PERIMEM_BRAMRWS(1 downto 0));
	v.mcfg2.ramwws	   := std_logic_vector(CFG_PERIMEM_BRAMWWS(1 downto 0));
        v.mcfg1.romrws     := "0001";
        v.mcfg1.romwws     := "0001";
        v.mcfg1.romwidth   := "11";
      end if;
      v.mcfg2.srdis        := '0';
      v.mcfg2.sdren        := '0';
    end if;
 
-- optional feeb-back from write stobe to data bus drivers
 
    if CFG_PERIMEM_WENDFB then bdrive := r.bdrive and memi.wrn;
    else bdrive := r.bdrive; end if;
 
-- pragma translate_off
    for i in dataout'range loop --'
      if is_x(dataout(i)) then dataout(i) := '1'; end if;
    end loop;
-- pragma translate_on
 
-- drive various register inputs and external outputs
 
    ri <= v; 
 
    memo.address(27 downto 0) <= r.address(27 downto 0);
    memo.ramsn(4 downto 0)  <= r.ramsn;
    memo.ramoen(4 downto 0) <= r.ramoen;
    memo.romsn       	<= r.romsn;
    memo.oen  		<= r.oen;
    memo.iosn  		<= r.iosn(0);
    memo.read  		<= r.read;
    memo.wrn 		<= r.wrn; 
    memo.writen 	<= r.writen;
    memo.bdrive  	<= bdrive;
    memo.data		<= r.writedata;
    sdi.idle 		<= bidle;
    sdi.haddr		<= haddr;
    sdi.rhaddr		<= r.haddr;
    sdi.nhtrans		<= htrans;
    sdi.rhtrans		<= r.htrans;
    sdi.htrans		<= ahbsi.htrans;
    sdi.hready		<= ahbsi.hready;
    sdi.hsize		<= r.size;
    sdi.hwrite		<= r.hwrite;
    sdi.hsel		<= sdhsel;
    sdi.enable		<= r.mcfg2.sdren;
 
 
    ahbso.hrdata <= dataout;
    ahbso.hready <= hready;
    ahbso.hresp  <= r.hresp;
    ahbso.hsplit <= (others => '0');
 
  end process;
 
 
  stdregs : process(clk,rst)
  begin 
    if rising_edge(clk) then r <= ri; end if;
    if rst = '0' then
      r.ramsn <= (others => '1'); r.romsn <= (others => '1');
      r.oen <= '1'; r.bdrive <= (others => '1');
      r.iosn <= "11"; r.ramoen <= (others => '1');
    end if;
  end process;
 
 
 
-- optional boot-prom
 
 promgen : if (CFG_PERIMEM_BOOT /= perimem_memory) generate
    bprom0 : bprom port map
 
      (clk => clk, cs => r.psel(0), addr => r.address, data => promdata);
 
  end generate;
 
-- optional sdram controller
 
  sd0 : if CFG_PERIMEM_SDRAMEN generate
    sdctrl : sdmctrl port map ( rst => rst, clk => clk, sdi => sdi, 
	sdo => sdo, apbi => apbi, apbo => sdapbo, wpo => wpo, sdmo => sdmo);
  end generate;
 
end;