--
-- OutputGenerator.vhd
--
-- Copyright (c) 2006 Mitsutaka Okazaki (brezza@pokipoki.org)
-- All rights reserved.
--
-- Redistribution and use of this source code or any derivative works, are
-- permitted provided that the following conditions are met:
--
-- 1. Redistributions of source code must retain the above copyright notice,
--    this list of conditions and the following disclaimer.
-- 2. Redistributions in binary form must reproduce the above copyright
--    notice, this list of conditions and the following disclaimer in the
--    documentation and/or other materials provided with the distribution.
-- 3. Redistributions may not be sold, nor may they be used in a commercial
--    product or activity without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
-- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
-- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
-- OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-- WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
-- OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
-- ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--
--
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use WORK.VM2413.ALL;

entity OutputGenerator is
  port (
    clk     : in std_logic;
    reset   : in std_logic;
    clkena  : in std_logic;
    slot    : in SLOT_TYPE;
    stage   : in STAGE_TYPE;

    rhythm  : in std_logic;
    opout   : in SIGNED_DB_TYPE;

    faddr  : in CH_TYPE;
    fdata  : out SIGNED_LI_TYPE;

    maddr  : in SLOT_TYPE;
    mdata  : out SIGNED_LI_TYPE
  );
end OutputGenerator;

architecture RTL of OutputGenerator is

  component FeedbackMemory port (
    clk    : in std_logic;
    reset  : in std_logic;
    wr     : in std_logic;
    waddr  : in CH_TYPE;
    wdata  : in SIGNED_LI_TYPE;
    raddr  : in CH_TYPE;
    rdata  : out SIGNED_LI_TYPE
  );
  end component;

  component OutputMemory port (
    clk    : in std_logic;
    reset  : in std_logic;
    wr     : in std_logic;
    addr   : in SLOT_TYPE;
    wdata  : in SIGNED_LI_TYPE;
    rdata  : out SIGNED_LI_TYPE;
    addr2  : in SLOT_TYPE;
    rdata2 : out SIGNED_LI_TYPE
  );
  end component;

  component LinearTable port (
    clk    : in std_logic;
    reset  : in std_logic;
    addr   : in  SIGNED_DB_TYPE;
    data   : out SIGNED_LI_TYPE
  );
  end component;

  function AVERAGE ( L : SIGNED_LI_TYPE ; R : SIGNED_LI_TYPE ) return SIGNED_LI_TYPE is
    variable vL, vR : std_logic_vector(LI_TYPE'high + 2 downto 0);
  begin

    if L.sign = '0' then
      vL := "00" & L.value;
    else
      vL := not ( "00" & L.value ) + '1';
    end if;
     if R.sign = '0' then
      vR := "00" & R.value;
    else
      vR := not ( "00" & R.value ) + '1';
    end if;

    vL := vL + vR;

    if vL(vL'high) = '0' then -- positive
      return ( sign => '0', value => vL(vL'high-1 downto 1) );
    else -- negative
      vL := not ( vL - '1' );
      return ( sign => '1', value => vL(vL'high-1 downto 1) );
    end if;

  end;

  signal fb_wr, mo_wr : std_logic;
  signal fb_addr : CH_TYPE;
  signal mo_addr : SLOT_TYPE;
  signal li_addr : SIGNED_DB_TYPE;
  signal li_data, fb_wdata, mo_wdata, mo_rdata : SIGNED_LI_TYPE;

begin

  Fmem : FeedbackMemory port map( clk, reset, fb_wr, fb_addr, fb_wdata, faddr, fdata );

  Mmem : OutputMemory port map( clk, reset, mo_wr, mo_addr, mo_wdata, mo_rdata, maddr, mdata );

  Ltbl : LinearTable port map( clk, reset, li_addr, li_data );

  process (clk, reset)

  begin

    if reset = '1' then

      mo_wr <= '0';
      fb_wr <= '0';

    elsif clk'event and clk = '1' then if clkena = '1' then

      if stage = 0 then

        mo_wr <= '0';
        fb_wr <= '0';

        mo_addr <= slot;
        li_addr  <= opout;

      elsif stage = 1 then

        -- wait for linear table data & feedback memory

      elsif stage = 2 then

        -- Store modulator output to feedback memory
        if slot mod 2 = 0 then
          fb_addr  <= slot/2;
          fb_wdata <= AVERAGE(mo_rdata, li_data);
          fb_wr <= '1';
        end if;

        -- Store raw output
        mo_addr <= slot;
        mo_wdata <= li_data;
        mo_wr <= '1';

      elsif stage = 3 then

        mo_wr <= '0';
        fb_wr <= '0';

      end if;

    end if; end if;

  end process;

end RTL;
