Subversion Repositories pcie_sg_dma

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-- Company:  ziti, Uni. HD

-- Engineer:  wgao

-- 

-- Create Date:    11:47:02 07 Dec 2006 

-- Design Name: 

-- Module Name:    Tx_Output_Arbitor - Behavioral 

-- Project Name: 

-- Target Devices: 

-- Tool versions: 

-- Description: 

--

-- Dependencies:

--

-- Revision 1.00 - first release.  14.12.2006

-- 

-- Additional Comments:

--                      Dimension can be easily expanded.

-- 

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

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

USE IEEE.STD_LOGIC_ARITH.ALL;

USE IEEE.STD_LOGIC_UNSIGNED.ALL;

library work;

use work.abb64Package.all;

-----------  Top entity   ---------------

entity Tx_Output_Arbitor is

        port (

              rst_n     : IN  std_logic;

              clk       : IN  std_logic;

              arbtake   : IN  std_logic;                                       -- take a valid arbitration by the user

              Req       : IN  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);  -- similar to FIFO not-empty

              bufread   : OUT std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);  -- Read FIFO

              Ack       : OUT std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0)   -- tells who is the winner

        );

end Tx_Output_Arbitor;

architecture Behavioral of Tx_Output_Arbitor is

  TYPE ArbStates is         (

                               aSt_Reset

                             , aSt_Idle

                             , aSt_ReadOne

                             , aSt_Ready

                             );

  signal Arb_FSM             : ArbStates;

  signal Arb_FSM_NS          : ArbStates;

  TYPE PriorMatrix is ARRAY (C_ARBITRATE_WIDTH-1 downto 0)

                               of std_logic_vector (C_ARBITRATE_WIDTH-1 downto 0);

  signal ChPriority          : PriorMatrix;

  signal Prior_Init_Value    : PriorMatrix;

  signal Wide_Req            : PriorMatrix;

  signal Wide_Req_turned     : PriorMatrix;

  signal  take_i             :  std_logic;

  signal  Req_i              :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  Req_r1             :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  read_prep          :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  read_i             :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  Indice_prep        :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  Indice_i           :  std_logic_vector(C_ARBITRATE_WIDTH-1 downto 0);

  signal  Champion_Vector    :  std_logic_vector (C_ARBITRATE_WIDTH-1 downto 0);

begin

   bufread   <= read_i;

   Ack       <= Indice_i;

   take_i    <= arbtake;

   Req_i     <= Req;

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

  Prior_Init_Value(0) <= C_LOWEST_PRIORITY;

  Gen_Prior_Init_Values:

    FOR i IN 1 TO C_ARBITRATE_WIDTH-1 generate

      Prior_Init_Value(i) <= Prior_Init_Value(i-1)(C_ARBITRATE_WIDTH-2 downto 0) & '1';

    end generate;

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

  --  Mask the requests

  -- 

  Gen_Wide_Requests:

    FOR i IN 0 TO C_ARBITRATE_WIDTH-1 generate

      Wide_Req(i) <= ChPriority(i) when Req_i(i)='1'

                     else C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

    end generate;

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

-- Synchronous Delay: Req

--

   Synch_Delay_Req:

   process(clk)

   begin

     if clk'event and clk = '1' then

       Req_r1  <= Req_i;

     end if;

   end process;

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

-- Synchronous: States

--

   Seq_FSM_NextState:

   process(clk, rst_n)

   begin

     if (rst_n = '0') then

       Arb_FSM <= aSt_Reset;

     elsif clk'event and clk = '1' then

       Arb_FSM <= Arb_FSM_NS;

     end if;

   end process;

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

-- Combinatorial: Next States

--

   Comb_FSM_NextState:

   process (

             Arb_FSM

           , take_i

           , Req_r1

           )

   begin

     case Arb_FSM  is

       when aSt_Reset  =>

          Arb_FSM_NS <= aSt_Idle;

       when aSt_Idle  =>

          if Req_r1 = C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0) then

             Arb_FSM_NS <= aSt_Idle;

          else

             Arb_FSM_NS <= aSt_ReadOne;

          end if;

       when aSt_ReadOne  =>

          if Req_r1 = C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0) then  -- Ghost Request !!!

             Arb_FSM_NS <= aSt_Idle;

          else

             Arb_FSM_NS <= aSt_Ready;

          end if;

       when aSt_Ready  =>

          if take_i = '0' then

             Arb_FSM_NS <= aSt_Ready;

          elsif Req_r1 = C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0) then

             Arb_FSM_NS <= aSt_Idle;

          else

             Arb_FSM_NS <= aSt_ReadOne;

          end if;

       when Others  =>

          Arb_FSM_NS <= aSt_Reset;

     end case;

   end process;

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

-- Turn the Request-Array Around

--

   Turn_the_Request_Array_Around:

       FOR i IN 0 TO C_ARBITRATE_WIDTH-1 generate

         Dimension_2nd:

         FOR j IN 0 TO C_ARBITRATE_WIDTH-1 generate

            Wide_Req_turned(i)(j) <= Wide_Req(j)(i);

         END generate;

       END generate;

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

-- Synchronous Calculation: Champion_Vector

--

   Sync_Champion_Vector:

   process(clk)

   begin

     if clk'event and clk = '1' then

       FOR i IN 0 TO C_ARBITRATE_WIDTH-1 LOOP

         if Wide_Req_turned(i)=C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0) then

            Champion_Vector(i) <= '0';

         else

            Champion_Vector(i) <= '1';

         end if;

       END LOOP;

     end if;

   end process;

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

--  Prepare the buffer read signal: read_i

-- 

   Gen_Read_Signals:

     FOR i IN 0 TO C_ARBITRATE_WIDTH-1 generate

       read_prep(i) <= '1' when Champion_Vector=ChPriority(i) else '0';

     end generate;

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

-- FSM Output :  Buffer read_i and Indice_i

--

   FSM_Output_read_Indice:

   process (clk, rst_n)

   begin

     if (rst_n = '0') then

       read_i      <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

       Indice_prep <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

       Indice_i    <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

     elsif clk'event and clk = '1' then

       case Arb_FSM is

         when aSt_ReadOne =>

           read_i      <= read_prep;

           Indice_prep <= read_prep;

           Indice_i    <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

         when aSt_Ready =>

           read_i      <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

           Indice_prep <= Indice_prep;

           if take_i ='1' then

            Indice_i    <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

           else

            Indice_i    <= Indice_prep;

           end if;

         when Others =>

           read_i      <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

           Indice_prep <= Indice_prep;

           Indice_i    <= C_ALL_ZEROS(C_ARBITRATE_WIDTH-1 downto 0);

       end case;

     end if;

   end process;

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

--

 Gen_Modify_Priorities:

   FOR i IN 0 TO C_ARBITRATE_WIDTH-1 generate

      Proc_Priority_Cycling:

      process (clk, rst_n)

      begin

        if (rst_n = '0') then

          ChPriority(i) <= Prior_Init_Value(i);

        elsif clk'event and clk = '1' then

          case Arb_FSM is

            when aSt_ReadOne =>

              if ChPriority(i) = Champion_Vector then

                 ChPriority(i) <= C_LOWEST_PRIORITY;

              elsif (ChPriority(i) and Champion_Vector) = Champion_Vector then

                 ChPriority(i) <= ChPriority(i);

              else

                 ChPriority(i) <= ChPriority(i)(C_ARBITRATE_WIDTH-2 downto 0) & '1';

              end if;

            when Others =>

                 ChPriority(i) <= ChPriority(i);

          end case;

        end if;

      end process;

  end generate;

end architecture Behavioral;