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-- Copyright 2015, Jürgen Defurne

--

-- This file is part of the Experimental Unstable CPU System.

--

-- The Experimental Unstable CPU System 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 3 of the

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

--

-- The Experimental Unstable CPU System 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 Experimental Unstable CPU System. If not, see

-- http://www.gnu.org/licenses/lgpl.txt.

-- This package is the main interface to the memory. When defining

-- different sizes, this package generates the main component.

-- The components themselves are responsible for using the contents

-- of the passed file name to initialise the memory array.

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.numeric_std.ALL;

PACKAGE RAM IS

  COMPONENT memory IS

    GENERIC (

      filename : STRING                := "";

      w_data   : NATURAL RANGE 1 TO 32 := 16;

      w_addr   : NATURAL RANGE 8 TO 15 := 10);

    PORT (

      clk : IN  STD_LOGIC;

      we  : IN  STD_LOGIC;

      a1  : IN  STD_LOGIC_VECTOR(w_addr - 1 DOWNTO 0);  -- Data port address

      a2  : IN  STD_LOGIC_VECTOR(w_addr - 1 DOWNTO 0);  -- Instruction port address

      d1  : IN  STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0);  -- Data port input

      q1  : OUT STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0);  -- Data port output

      q2  : OUT STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0));  -- Instruction port output

  END COMPONENT memory;

END PACKAGE RAM;

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.numeric_std.ALL;

USE work.ram_parts.ALL;

USE work.hexio.ALL;

ENTITY memory IS

  -- Memory component based upon Xilinx Spartan-6 block RAM

  -- Maximum capacity is 16k words

  -- This component can be initialised by passing a file name as a generic

  -- parameter.

  GENERIC (

    filename : STRING                := "";

    w_data   : NATURAL RANGE 1 TO 32 := 16;

    w_addr   : NATURAL RANGE 8 TO 15 := 10);

  PORT (

    clk : IN  STD_LOGIC;

    we  : IN  STD_LOGIC;

    a1  : IN  STD_LOGIC_VECTOR(w_addr - 1 DOWNTO 0);  -- Data port address

    a2  : IN  STD_LOGIC_VECTOR(w_addr - 1 DOWNTO 0);  -- Instruction port address

    d1  : IN  STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0);  -- Data port input

    q1  : OUT STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0);  -- Data port output

    q2  : OUT STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0));  -- Instruction port output

END memory;

ARCHITECTURE Structural OF memory IS

  CONSTANT dummy : INTEGER := notify_f("Initialisation of memory component starts");

BEGIN  -- Structural

  SMALL_MEM : IF w_addr >= 8 AND w_addr <= 14 GENERATE

    MEM0 : RAM_GENERIC

      GENERIC MAP (

        filename => filename,

        w_data   => w_data,

        w_addr   => w_addr)

      PORT MAP (

        clk => clk,

        we  => we,

        a1  => a1,

        a2  => a2,

        d1  => d1,

        q1  => q1,

        q2  => q2);

  END GENERATE SMALL_MEM;

  LARGE_MEM : IF w_addr = 15 GENERATE

    MEM1 : RAM32K

      GENERIC MAP (

        filename => filename,

        w_data   => w_data)

      PORT MAP (

        clk => clk,

        we  => we,

        a1  => a1,

        a2  => a2,

        d1  => d1,

        q1  => q1,

        q2  => q2);

  END GENERATE LARGE_MEM;

END Structural;