Subversion Repositories mips_enhanced

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

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

--  Copyright (C) 2004 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.

--

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

--

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

-- Entity:      ahbrom

-- File:        ahbrom.vhd

-- Author:      Jiri Gaisler - Gaisler Research

-- Description: AHB rom. 0/1-waitstate read

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

library ieee;

use ieee.std_logic_1164.all;

library grlib;

use grlib.amba.all;

use grlib.stdlib.all;

use grlib.devices.all;

entity ahbrom is

  generic (

    hindex  : integer := 0;

    haddr   : integer := 0;

    hmask   : integer := 16#fff#;

    pipe    : integer := 0;

    tech    : integer := 0;

    kbytes  : integer := 1);

  port (

    rst     : in  std_ulogic;

    clk     : in  std_ulogic;

    ahbsi   : in  ahb_slv_in_type;

    ahbso   : out ahb_slv_out_type

  );

end;

architecture rtl of ahbrom is

constant abits : integer := 17;

constant bytes : integer := 89996;

constant hconfig : ahb_config_type := (

  4 => ahb_membar(haddr, '1', '1', hmask), others => zero32);

signal romdata : std_logic_vector(31 downto 0);

signal addr : std_logic_vector(abits-1 downto 2);

signal hsel, hready : std_ulogic;

begin

  ahbso.hresp   <= "00";

  ahbso.hsplit  <= (others => '0');

  ahbso.hirq    <= (others => '0');

  ahbso.hcache  <= '1';

  ahbso.hconfig <= hconfig;

  ahbso.hindex  <= hindex;

  reg : process (clk)

  begin

    if rising_edge(clk) then

      addr <= ahbsi.haddr(abits-1 downto 2);

    end if;

  end process;

  p0 : if pipe = 0 generate

    ahbso.hrdata  <= romdata;

    ahbso.hready  <= '1';

  end generate;

  p1 : if pipe = 1 generate

    reg2 : process (clk)

    begin

      if rising_edge(clk) then

        hsel <= ahbsi.hsel(hindex) and ahbsi.htrans(1);

        hready <= ahbsi.hready;

        ahbso.hready <=  (not rst) or (hsel and hready) or

          (ahbsi.hsel(hindex) and not ahbsi.htrans(1) and ahbsi.hready);

        ahbso.hrdata  <= romdata;

      end if;

    end process;

  end generate;

  comb : process (addr)

  begin

    case conv_integer(addr) is

    when 16#00000# => romdata <= X"88100000";

    when 16#00001# => romdata <= X"09100031";

    when 16#00002# => romdata <= X"81C12314";

    when 16#00003# => romdata <= X"01000000";

    when 16#00004# => romdata <= X"A1480000";

    when 16#00005# => romdata <= X"A7500000";

    when 16#00006# => romdata <= X"10800836";

    when others => romdata <= (others => '-');

    end case;

  end process;

  -- pragma translate_off

  bootmsg : report_version

  generic map ("ahbrom" & tost(hindex) &

  ": 32-bit AHB ROM Module,  " & tost(bytes/4) & " words, " & tost(abits-2) & " address bits" );

  -- pragma translate_on

  end;