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

-- test2.vhd

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

-- project: HPC-16 Microprocessor

--

-- usage: basic testbench top-level

--

-- dependency: cpu.vhd, ramNx16.vhd

--

-- Author: M. Umair Siddiqui (umairsiddiqui@opencores.org)

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

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

--                                                                                --

--    Copyright (c) 2005, M. Umair Siddiqui all rights reserved                   --

--                                                                                --

--    This file is part of HPC-16.                                                --

--                                                                                --

--    HPC-16 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.                                         --

--                                                                                --

--    HPC-16 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 HPC-16; if not, write to the Free Software                       --

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

--                                                                                --

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;

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

entity test2 is

  generic

  (

    clk_period          : time    := 40 ns;

    half_clk_period     : time    := 20 ns;

    --

    cpu_pc_preset_value : std_logic_vector(15 downto 0) := X"0000";

    cpu_sp_preset_value : std_logic_vector(15 downto 0) := X"001e";

    --

    ram_adr_width       : integer := 4;

    file_name_prefix    : string  := "prog1";

    sim_stop_time       : time    := 1500 ns

  );

end test2;

architecture sim of test2 is

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

  -- cpu interface signal

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

  signal clk_i : std_logic;

  signal rst_i : std_logic;

  signal ack_i : std_logic;

  signal intr_i : std_logic;

  --

  signal sel_o : std_logic_vector(1 downto 0);

  signal stb_o : std_logic;

  signal cyc_o : std_logic;

  signal we_o  : std_logic;

  --

  signal inta_cyc_o : std_logic;

  signal i_cyc_o    : std_logic;

  signal c_cyc_o    : std_logic;

  signal d_cyc_o    : std_logic;

  --

  signal adr_o : std_logic_vector(15 downto 0);

  signal dat_io : std_logic_vector(15 downto 0);

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

  -- ram interfacing

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

  signal ram_cs : std_logic;

  signal ram_oe : std_logic;

begin

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

  ram_cs_gen : process(stb_o, adr_o)

    variable temp : integer;

    constant max_loc : integer := (2 ** (ram_adr_width + 1)) - 1;

  begin

    if stb_o = '1' then

      temp := conv_integer(adr_o);

      if 0 <= temp and temp <= max_loc then

        ram_cs <= '1';

      else

        ram_cs <= '0';

      end if;

    end if;

  end process ram_cs_gen;

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

  ram_oe <= not we_o;

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

  clk_gen : process

  begin

    wait for half_clk_period;

    clk_i <= '1';

    wait for half_clk_period;

    clk_i <= '0';

    if now >= sim_stop_time then

      assert false

        report "simulation completed (not an error)"

        severity error;

      wait;

    end if;

  end process;

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

  rst_gen : process

  begin

    wait for half_clk_period;

    rst_i <= '1';

    wait for 4 * clk_period;

    rst_i <= '0';

    wait;

  end process;

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

  ram: entity work.ramNx16(async)

  generic map

  (

    init_file_name => file_name_prefix & "_init_ram.txt",

    adr_width => ram_adr_width

  )

  port map

  (

    clk => clk_i,

    adr => adr_o(ram_adr_width downto 1),

    dat_i => dat_io,

    --

    cs => ram_cs,

    we => we_o,

    ub => sel_o(1),

    lb => sel_o(0),

    oe => ram_oe,

    --

    dat_o => dat_io

  );

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

  cpu : entity work.cpu

  generic map

  (

    pc_preset_value => cpu_pc_preset_value,

    sp_preset_value => cpu_sp_preset_value

  )

  port map

  (

     CLK_I => clk_i,

     RST_I => rst_i,

     ACK_I => ack_i,

     INTR_I => intr_i,

     --

     SEL_O => sel_o,

     STB_O => stb_o,

     CYC_O => cyc_o,

     WE_O => we_o,

     --

     INTA_CYC_O => inta_cyc_o,

     I_CYC_O => i_cyc_o,

     C_CYC_O => c_cyc_o,

     D_CYC_O => d_cyc_o,

     --

     DAT_IO => dat_io,

     ADR_O => adr_o

  );

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

  ack_gen : ack_i <= stb_o;

end sim;