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

-- Funbase IP library Copyright (C) 2011 TUT Department of Computer Systems

--

-- This source file may be used and distributed without

-- restriction provided that this copyright statement is not

-- removed from the file and that any derivative work contains

-- the original copyright notice and the associated disclaimer.

--

-- This source file 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.

--

-- This source 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 this source; if not, download it

-- from http://www.opencores.org/lgpl.shtml

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

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

-- File        : fifo_muxes.vhdl

-- Description : Makes two fifos look like a single fifo.

--               Two components : one for writing and one for reading fifo.

--

--               Write_demux:

--               Input : data, addr valid and command 

--               Out   : data, addr valid and command to two fifos

--

--               Read_mux :

--               Input : data, addr valid and command from two fifos

--               Out   : data, addr valid and command

--

--              NOTE:

--              1) Fifo_mux_read does not fully support One_Data_Left_Out!

--

--              It works when writing to fifo. However, when something

--              is written to empty fifo, One_Data_Left_Out remains 0

--              even if Empty goes from 1 to 0! Be careful out there.

--

--              Case when new addr is written to fifo 0 and there is a gap before

--              corresponding data. At the same time there is some data in fifo

--              #1. It is not wise to wait for data#0, because it blocks the data#1.

--              In such case, transfer from fifo#0 is interrupted (Empty goes high).

--              At the moment, One_Data_Left_Out does not work in such case.

--              (Probably it could be repaired with fifo_bookkeeper component?)

--

--              2) Fifo_demux_write does not fully support One_Place_Left_Out!

--

--              When nothing is written to fifo, demux does not know which one-place

--              to select for output. When writing begins, it is possible that

--              target fifo becomes immediately full. The writer has no warning

--              of this event because one_place_left was zero before writing.

--              Same may happen when target fifo changes, e.g. data to msg

--              without interruption

--              Try-out : OR one-place_left signals together when command is IDLE

--              Caution : May prevent writing to one fifo if the other fifo is

--              is geting full.

--

--              

-- Author      : Erno Salminen

-- e-mail      : erno.salminen@tut.fi

-- Project     : Mikälie

-- Design      : Do not use term design when you mean system

-- Date        : 05.02.2003

-- Modified    : 

-- 18.09.03     ES generic Comb_delayG added to avoid zero delay oscillation in

--                 simulation

--

--              AK When no comm, full-signal is OR-red in write-demux

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;

use work.hibiv2_pkg.all;

-- Write_Mux checks the incoming addr. Same addr is not

-- written to fifo more than once! Written fifo is selected

-- according to incoming command

-- 13.04 Fully asynchronous!

entity fifo_demux_wr is

  generic (

--    comb_delay_g :     time    := 1 ns;  -- 18.09.03

    data_width_g :     integer := 0;

    comm_width_g :     integer := 0

    );

  port (

    data_in      : in  std_logic_vector (data_width_g-1 downto 0);

    av_in        : in  std_logic;

    comm_in      : in  std_logic_vector (comm_width_g-1 downto 0);

    we_in        : in  std_logic;

    full_out     : out std_logic;

    one_p_out    : out std_logic;

    -- Data/Comm/AV conencted to both fifos

    -- Distinction made with WE!

    data_out   : out std_logic_vector ( data_width_g-1 downto 0);

    comm_out   : out std_logic_vector ( comm_width_g-1 downto 0);

    av_out     : out std_logic;

    we_0_out   : out std_logic;

    we_1_out   : out std_logic;

    full_0_in  : in  std_logic;

    full_1_in  : in  std_logic;

    one_p_0_in : in  std_logic;

    one_p_1_in : in  std_logic

    );

end fifo_demux_wr;

architecture rtl of fifo_demux_wr is

  -- Selects if debug prints are used (1-3) or not ('0')

  constant dbg_level : integer range 0 to 3 := 0;  -- 0= no debug, use 0 for synthesis

  -- Registers may be reset to 'Z' to 'X' so that reset state is clearly

  -- distinguished from active state. Using value of rst_value_arr array(dbg_level),

  -- the rst value may be easily set to '0' for synthesis.

  constant rst_value_arr : std_logic_vector ( 6 downto 0) := 'X' & 'Z' & 'X' & 'Z' & 'X' & 'Z' & '0';

begin  -- rtl

  -- Concurrent assignments

  av_out   <= av_in;

  data_out <= data_in;

  comm_out <= comm_in;

  -- COMB PROC

  -- Fully combinational

  Demultiplex_data : process (-- data_in,

                              -- av_in,

                              comm_in, we_in,

                              one_p_0_in, one_p_1_in,

                              full_0_in, full_1_in)

  begin  -- process Demultiplex_data

    if comm_in = conv_std_logic_vector (3, comm_width_g)

      or comm_in = conv_std_logic_vector (7, comm_width_g) then

      -- MESSAGE

      we_0_out  <= we_in;--     after comb_delay_g;

      we_1_out  <= '0';

      full_out  <= full_0_in;-- after comb_delay_g;

      one_p_out <= one_p_0_in;

    elsif comm_in = conv_std_logic_vector (2, comm_width_g)

      or comm_in = conv_std_logic_vector (4, comm_width_g)

      or comm_in = conv_std_logic_vector (6, comm_width_g) then

      -- DATA

      we_0_out  <= '0';

      we_1_out  <= we_in;--     after comb_delay_g;

      full_out  <= full_1_in;-- after comb_delay_g;

      one_p_out <= one_p_1_in;

    elsif comm_in = conv_std_logic_vector (1, comm_width_g)

      or comm_in = conv_std_logic_vector (5, comm_width_g) then

      -- CONFIG

      assert false report "Config comm to fifo_demux_wr" severity warning;

      we_0_out  <= '0';

      we_1_out  <= '0';

      full_out  <= '0';

      one_p_out <= '0';

    else

      --IDLE

      we_0_out  <= '0';

      we_1_out  <= '0';

      full_out  <= full_1_in or full_0_in; -- 18.03.05 0'

      one_p_out <= one_p_0_in or one_p_1_in;  -- 24.07 '0';

    end if;

  end process Demultiplex_data;

end rtl;                                --fifo_demux_wr

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

--entity fifo_mux_read kaytetaan lukemaan kahdesta fifosta osoite ja data perakkain

-- fifolla 0 on suurempi prioritetti. Jos ollaan lukemassa fifoa 1, ei ruveta

-- lukemaan fifoa 0 ennekuin on siirretty ainakin yksi data fifosta 1.

-- File        : fifo_muxes.vhdl

-- Description : Makes two fifos look like a single fifo for the reader

-- Author      : Erno Salminen

-- e-mail      : erno.salminen@tut.fi

-- Project     : Mikälie

-- Project     : Mikälie

-- Date        : 05.02.2003

-- Modified    : 

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;

entity fifo_mux_rd is

  generic (

    data_width_g :     integer := 0;

    comm_width_g :     integer := 0

    );

  port (

    clk          : in  std_logic;

    rst_n        : in  std_logic;

    data_0_in    : in  std_logic_vector ( data_width_g-1 downto 0);

    comm_0_in    : in  std_logic_vector ( comm_width_g-1 downto 0);

    av_0_in      : in  std_logic;

    one_d_0_in   : in  std_logic;

    empty_0_in   : in  std_logic;

    re_0_Out     : out std_logic;

    data_1_in    : in  std_logic_vector ( data_width_g-1 downto 0);

    comm_1_in    : in  std_logic_vector ( comm_width_g-1 downto 0);

    av_1_in      : in  std_logic;

    one_d_1_in   : in  std_logic;

    empty_1_in   : in  std_logic;

    re_1_Out     : out std_logic;

    re_in        : in  std_logic;

    data_out     : out std_logic_vector ( data_width_g-1 downto 0);

    comm_out     : out std_logic_vector ( comm_width_g-1 downto 0);

    av_out       : out std_logic;

    one_d_Out    : out std_logic;

    empty_Out    : out std_logic

    );

end fifo_mux_rd;

architecture rtl of fifo_mux_rd is

  -- Selects if debug prints are used (1-3) or not ('0')

  constant dbg_level : integer range 0 to 3 := 0;  -- 0= no debug, use 0 for synthesis

  -- Registers may be reset to 'Z' to 'X' so that reset state is clearly

  -- distinguished from active state. Using dbg_level+rst_value_arr array, the rst value may

  -- be easily set to '0' for synthesis.

  constant rst_value_arr : std_logic_vector ( 6 downto 0) := 'X' & 'Z' & 'X' & 'Z' & 'X' & 'Z' & '0';

  type addr_comm_type is record

                           addr : std_logic_vector ( data_width_g -1 downto 0);

                           comm : std_logic_vector ( comm_width_g -1 downto 0);

                         end record;

  signal last_addr_0_r : addr_comm_type;

  signal last_addr_1_r : addr_comm_type;

  signal curr_state_r : integer range 0 to 5;

  -- Transferred_Reg - siirron tila

  -- 00) Ei ole siirretty viela mitaan, saman tien pois. Alkutila ilman resettia.

  -- 01) Osoite fifossa 0

  -- 02) data   fifossa 0

  -- 03) Osoite fifosta 1

  -- 04) data   fifosta 1

  -- 05) molemmat fifot tyhjia. Alkutila resetissa.

  -- Tilasiirtymat

  -- 00 -> 05

  -- 01 -> 02

  -- 02 -> 01, 02, 03

  -- 03 -> 04

  -- 04 -> 01, 04, 05

  -- 05 -> 01, 03

begin  -- rtl

  -- COMB PROC

  Assign_Outputs : process (curr_state_r,

                            av_1_in, av_0_in,

                            data_1_in, data_0_in,

                            comm_1_in, comm_0_in,

                            empty_1_in, empty_0_in,

                            one_d_1_in, one_d_0_in,

                            Last_Addr_0_r, Last_Addr_1_r,

                            re_in

                            )

  begin  -- process Assign_Outputs

      case curr_state_r is

        when 0                 =>

          -- Ei ole tehty mitaan

          data_out  <= (others => rst_value_arr (dbg_level *1));

          comm_out  <= (others => rst_value_arr (dbg_level *1));

          av_out    <= '0';

          empty_Out <= '1';

          re_0_Out  <= '0';

          re_1_Out  <= '0';

        when 1 =>

          -- Osoite fifossa 0

          -- Siirretaan osoite 0

          -- joko rekisterista (sama osoite kuin viimeksikin)

          -- tai suoraan fifosta (uusi osoite, otetaan se myos talteen)

          if av_0_in = '1' then

            -- Uusi osoite

            data_out <= data_0_in;

            comm_out <= comm_0_in;

            re_0_Out <= re_in;

          else

            data_out <= Last_Addr_0_r.addr;

            comm_out <= Last_Addr_0_r.comm;

            re_0_Out <= '0';

          end if;

          av_out    <= '1';

          empty_Out         <= '0';

          re_1_Out          <= '0';

        when 2 =>

          -- data fifossa 0

          -- Siirretaan data fifosta 0

          if av_0_in = '1' and one_d_0_in = '1' then

            -- Fifossa 0 pelkka osoite

            if empty_1_in = '1'

              or (av_1_in = '1' and one_d_1_in = '1') then

              -- Fifo 1 tyhja tai siella pelkka osoite

              re_0_Out  <= '0';

              re_1_Out  <= '0';

              data_out  <= (others => rst_value_arr (dbg_level *2));

              comm_out  <= (others => rst_value_arr (dbg_level *2));

              av_out    <= '0';

              empty_Out <= '1';

            else

              -- Fifossa 1 olisi jotain, otetaan varman paalle

              re_0_Out  <= '0';

              re_1_Out  <= '0';

              data_out  <= (others => rst_value_arr (dbg_level *2));

              comm_out  <= (others => rst_value_arr (dbg_level *2));

              av_out    <= '0';

              empty_Out <= '1';

            end if;  --e_1 || (av1&1left1)            

          else

            -- Fifossa 0 osoite+jotain tai dataa

            re_0_Out    <= re_in;

            re_1_Out    <= '0';

            data_out  <= data_0_in;

            comm_out  <= comm_0_in;

            av_out    <= av_0_in;

            empty_Out <= empty_0_in;

          end if;  --av_1

        when 3                      =>

          -- Osoite fifossa 1

          -- Siirretaan osoite 1

          if av_1_in = '1' then

            -- Uusi osoite

            data_out <= data_1_in;

            comm_out <= comm_1_in;

            re_1_Out <= re_in;

          else

            data_out <= Last_Addr_1_r.addr;

            comm_out <= Last_Addr_1_r.comm;

            re_1_Out <= '0';

          end if;

          re_0_Out   <= '0';

          av_out     <= '1';

          empty_Out  <= '0';

        when 4 =>

          -- data fifossa 1

          -- Siirretaan fifosta 1

          if av_1_in = '1' and one_d_1_in = '1' then

            -- Fifossa 1 pelkka osoite

            if empty_0_in = '1'

              or (av_0_in = '1' and one_d_0_in = '1') then

              -- Fifo 0 tyhja tai siella pelkka osoite

              re_0_Out  <= '0';

              re_1_Out  <= '0';

              data_out  <= (others => rst_value_arr (dbg_level *2));

              comm_out  <= (others => rst_value_arr (dbg_level *2));

              av_out    <= '0';

              empty_Out <= '1';

            else

              -- Fifossa 0 olisi jotain, otetaan varman paalle

              re_0_Out  <= '0';

              re_1_Out  <= '0';

              data_out  <= (others => rst_value_arr (dbg_level *2));

              comm_out  <= (others => rst_value_arr (dbg_level *2));

              av_out    <= '0';

              empty_Out <= '1';

            end if;  --e_0 || (av0&1left0)            

          else

            -- Fifossa 1 osoite+jotain tai dataa

            re_0_Out    <= '0';

            re_1_Out    <= re_in;

            data_out  <= data_1_in;

            comm_out  <= comm_1_in;

            av_out    <= av_1_in;

            empty_Out <= empty_1_in;

          end if;  --av_1

        when 5                 =>

          -- Molemmat fifot tyhjia

          re_0_Out  <= '0';

          re_1_Out  <= '0';

          data_out  <= (others => rst_value_arr (dbg_level *1));

          comm_out  <= (others => rst_value_arr (dbg_level *1));

          av_out    <= '0';

          empty_Out <= '1';

        when others            =>

          re_0_Out  <= '0';

          re_1_Out  <= '0';

          data_out  <= (others => rst_value_arr (dbg_level));

          comm_out  <= (others => rst_value_arr (dbg_level));

          av_out    <= '0';

          empty_Out <= '1';

          assert false report "Illegal state in fifo_mux_rd" severity warning;

      end case;

  end process Assign_Outputs;

  -- SEQ PROC

  Reg_proc : process (clk, rst_n)

  begin  -- process Reg_proc

    if rst_n = '0' then                 -- asynchronous reset (active low)

      curr_state_r       <= 5;

      Last_Addr_0_r.addr <= (others => rst_value_arr (dbg_level));

      Last_Addr_0_r.comm <= (others => rst_value_arr (dbg_level));

      Last_Addr_1_r.addr <= (others => rst_value_arr (dbg_level));

      Last_Addr_1_r.comm <= (others => rst_value_arr (dbg_level));

    elsif clk'event and clk = '1' then  -- rising clock edge

      case curr_state_r is

        when 0 =>

          --           -- Ei ole tehty mitaan

          -- Tassa tilassa ei kauaa viihdy.

          curr_state_r <= 5;

        when 1 =>

          -- Siirretaan osoite 0

          -- joko rekisterista (sama osoite kuin viimeksikin)

          -- tai suoraan fifosta (uusi osoite, otetaan se myos talteen)

          if re_in = '1' then

            curr_state_r <= 2;

          else

            curr_state_r <= 1;

          end if;

          if av_0_in = '1' then

            -- Uusi osoite

            Last_Addr_0_r.addr <= data_0_in;

            Last_Addr_0_r.comm <= comm_0_in;

          else

            Last_Addr_0_r      <= Last_Addr_0_r;

          end if;

        when 2 =>

          -- Siirretaan fifosta 0

          if re_in = '1' then

            -- Luetaan fifosta 0

            if one_d_0_in = '1' then

              -- Oli viim data fifossa 0

              if empty_1_in = '1'

              or (av_1_in = '1' and one_d_1_in = '1') then

                -- Myos fifo 1 tyhja tai siella pelkka osoite

                curr_state_r <= 5;

              else

                -- Siirretaan osoite 1 (fifosta tai rekisterista)

                curr_state_r <= 3;

              end if;                   --empty_1_in

              Last_Addr_0_r <= Last_Addr_0_r;

              Last_Addr_1_r <= Last_Addr_1_r;

            else

              -- Fifossa 0 lukemisen jalkeenkin viela jotain

              curr_state_r       <= 2;

              Last_Addr_1_r <= Last_Addr_1_r;

              if av_0_in = '1' then

                -- fifosta 0 luettiin osoite

                Last_Addr_0_r.addr <= data_0_in;

                Last_Addr_0_r.comm <= comm_0_in;

              else

                -- Fifosta 0 luettiin dataa

                Last_Addr_0_r      <= Last_Addr_0_r;

              end if;  --av_0_in

            end if;  --empty_0_in

          else

            -- Odotellaan etta data luetaan

            curr_state_r       <= 2;

            Last_Addr_0_r <= Last_Addr_0_r;

            Last_Addr_1_r <= Last_Addr_1_r;

          end if;  --re_in

        when 3 =>

          -- Siirretaan osoite 1

          if re_in = '1' then

              curr_state_r <= 4;

          else

            -- Odotellaan lukua

            curr_state_r <= 3;

          end if;

          if av_1_in = '1' then

            -- Uusi osoite

            Last_Addr_1_r.addr <= data_1_in;

            Last_Addr_1_r.comm <= comm_1_in;

          else

            Last_Addr_1_r <= Last_Addr_1_r;

          end if;

        when 4 =>

          -- Siirretaan fifosta 1

          if re_in = '1' then

            -- Luetaan fifoa 1

            if av_1_in = '1' then

              -- Luetaan osoite fifosta 1

              Last_Addr_0_r      <= Last_Addr_0_r;

              Last_Addr_1_r.addr <= data_1_in;

              Last_Addr_1_r.comm <= comm_1_in;

              if one_d_1_in = '1' then

                -- fifossa oli pelkka osoite

                -- puolittainen VIRHE?

                --assert false report "Was? 1" severity note;

                curr_state_r <= 5;

              else

                -- Fifossa 1 on myos dataa, luetaan se 

                -- ennen (mahdollista) siirtymista

                -- fifon 1 lukemiseen

                curr_state_r <= 4;

              end if;  --one_d_1_in

            else

              -- Luetaan data fifosta 1

              if empty_0_in = '1'

                or (av_0_in = '1' and one_d_0_in = '1') then

                -- Fifo 0 tyhja tai siella pelkka osoite

                if one_d_1_in = '0' then

                  -- Onneksi fifossa 1 on viela jotain

                  curr_state_r <= 4;

                else

                  -- Ei ole siis kummassakaan fifossa mit'n

                  curr_state_r <= 5;

                end if;  -- one_d_1_in

              else

                -- fifossa 0 luettavaa

                -- siirretann siis osoite 1 seuraavaksi (fifosta/rekisterista)

                curr_state_r       <= 1;

                Last_Addr_0_r <= Last_Addr_0_r;

                Last_Addr_1_r <= Last_Addr_1_r;

              end if;  --empty_0_in or (av0 & 1left_0)

            end if;  --av_0_in

          else

            -- Odotetaan etta luetaan fifoa 1

            --curr_state_r       <= 4;

            Last_Addr_0_r <= Last_Addr_0_r;

            Last_Addr_1_r <= Last_Addr_1_r;

            if av_1_in = '1' and one_d_1_in ='1' then

              -- Ei olekaan kuin pelkka osoite fifossa #1!

              if empty_0_in = '1'

                or (av_0_in = '1' and one_d_0_in ='1') then

                -- Ei ole fifossa 0 :kaan mitaan jarkevaa

                curr_state_r <= 5;

              else

                -- Voidaan siirtaa osoite 0 seuraavaksi

                curr_state_r <= 1;

              end if;

            else

              -- fifossa 1 on myos dataa, odotellaan lukemista

              curr_state_r <= 4;

            end if;

          end if;  --re_in

        when 5 =>

          -- Ei voitu lukea kummastakaan fifosta

          Last_Addr_0_r <= Last_Addr_0_r;

          Last_Addr_1_r <= Last_Addr_1_r;

          if empty_0_in = '1' or ( av_0_in = '1' and one_d_0_in ='1') then

            -- Fifo 0 tyhja tai siella pelkka osoite

            if empty_1_in = '1' or ( av_1_in = '1' and one_d_1_in ='1') then

              -- Fifo 1 tyhja tai siella pelkka osoite

              -- => KUmmastakaan ei voi lukea

              curr_state_r       <= 5;

            else

              -- Fifossa 1 jotain

              -- siirretann siis osoite 1 seuraavaksi (fifosta/rekisterista)

              curr_state_r <= 3;

            end if;--empty_0_in or (av0 & 1left_0)

          else

            -- Fifossa 0 jotain

            -- siirretann siis osoite 0 seuraavaksi (fifosta/rekisterista)

            curr_state_r <= 1;

          end if; --empty_0_in or (av0 & 1left_0)

        when others =>

          assert false report "Illegal state in fifo_mux_rd" severity warning;

      end case;

    end if;

  end process Reg_proc;

  -- one_d_Out on sen verta vaikea, etta tehdaan se omassa prosessissaan

  Assign_1_D_Left_Out : process (curr_state_r,

                                 -- data_0_in,     data_1_in,

                                 -- comm_0_in,     comm_1_in,

                                 empty_0_in,    empty_1_in,

                                 av_0_in,       av_1_in,

                                 one_d_0_in,    one_d_1_in--,

                                 -- Last_Addr_0_r, Last_Addr_1_r,

                                 -- re_in

                                 )

  begin  -- process Assign_1_D_Left_Out

      case curr_state_r is

        when 0                         =>

          -- Ei ole tehty mitaan

          one_d_Out <= '0';

        when 1 =>

          -- Siirretaan osoite 0

          -- ellei ihmeita tapahdu, one_d_Out pitaisi olla 0!

          if av_0_in = '1' then

            --Olisi syyta olla dataakin fifossa 0, toivotaan

            one_d_Out <= '0';

          else

            -- Sama osoite kuin viimeksi (rekisterista)

            if empty_0_in = '1' then

              -- Fifossa 0 tyhja

              assert false report

                "Retrsnferring addr#0, but fifo#0 is empty. ERROR?" severity warning;

              if empty_1_in = '1'