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MGTR

SndWords

Documentation for architecture MGTR/SndWords/a0

VHDL Contents

    1  -- EASE/HDL begin --------------------------------------------------------------
    2  -- 
    3  -- Architecture 'a0' of entity 'SndWords'.
    4  -- 
    5  --------------------------------------------------------------------------------
    6  -- 
    7  -- Copy of the interface declaration:
    8  -- 
    9  --   port(
   10  --     CAV   : out    std_logic;
   11  --     DAV   : out    std_logic;
   12  --     Data  : out    std_logic_vector(31 downto 0);
   13  --     EAV   : out    std_logic;
   14  --     EnSD  : in     std_logic;
   15  --     EnSX  : in     std_logic;
   16  --     LWD   : in     std_logic_vector(31 downto 0);
   17  --     LWX   : in     std_logic_vector(31 downto 0);
   18  --     RqD   : out    std_logic;
   19  --     RqX   : out    std_logic;
   20  --     Rst_n : in     std_logic;
   21  --     WDE   : in     std_logic;
   22  --     WXE   : in     std_logic;
   23  --     XClk  : in     std_logic);
   24  -- 
   25  -- EASE/HDL end ----------------------------------------------------------------
   26  
   27  architecture a0 of SndWords is
   28  
   29    type states is (doIdle1, doIdle2, doData, doCarExt, doEData);
   30    signal state  : states;
   31    signal CDS    : std_logic_vector(2 downto 0);
   32    signal RDX    : std_logic_vector(1 downto 0);
   33    signal RqData : std_logic;
   34    signal RqCExt : std_logic;
   35    signal Toggle : std_logic;
   36    signal Cycle  : unsigned (6 downto 0);
   37    signal ForceIdle : std_logic;
   38  
   39  begin
   40  
   41    Data <= LWD when (CDS(0) = '0') else LWX;
   42  
   43    CAV  <= CDS(2);
   44    DAV  <= CDS(1);
   45    EAV  <= Toggle;
   46    RqD  <= RDX(1);
   47    RqX  <= RDX(0);
   48  
   49    --RqData <= not WDE;                            -- fifo not empty
   50    --RqCExt <= not WXE;                            -- fifo not empty
   51  
   52    RqData <= '1' when (WDE = '0' and EnSD = '1') else '0';   -- when D fifo not empty
   53    RqCExt <= '1' when (WXE = '0' and EnSX = '1') else '0';   -- when X fifo not empty
   54  
   55    ForceIdle <= '1' when (Cycle(4 downto 0) = 31) else '0';
   56    --ForceIdle <= '1' when (Cycle(3 downto 0) = 15) else '0';
   57  
   58    prTrx:
   59    process (XClk, Rst_n)
   60    begin
   61      if (Rst_n = '0') then
   62        Toggle <= '0';
   63        CDS    <= "000";                  -- CAV, DAV, Select eXtra
   64        RDX    <= "00";                   -- Request Data or eXtra
   65        state  <= doIdle1;
   66        Cycle  <= (others => '0');
   67      elsif (rising_edge(XClk)) then
   68        if (Toggle = '1') then
   69          Toggle <= '0';
   70          case state is
   71          when doIdle1 =>
   72            CDS  <= "000";                -- CAV, DAV, Select eXtra
   73            RDX  <= "00";                 -- Request Data or eXtra
   74            state <= doIdle2;
   75          when doIdle2 =>
   76            CDS  <= "000";                -- CAV, DAV, Select eXtra
   77            if (RqData = '1') then
   78              RDX   <= "10";              -- Request Data or eXtra
   79              state <= doData;
   80            elsif (RqCExt = '1') then
   81              RDX   <= "01";              -- Request Data or eXtra
   82              state <= doCarExt;
   83            else
   84              RDX   <= "00";              -- Request Data or eXtra
   85              state <= doIdle1;
   86            end if;
   87          when doData =>
   88            CDS   <= "010";               -- CAV, DAV, Select eXtra
   89            Cycle <= Cycle + 1;
   90            if (ForceIdle = '1') then
   91              RDX   <= "00";              -- Request Data or eXtra
   92              state <= doIdle1;
   93            elsif (RqCExt = '1') then
   94              RDX   <= "01";              -- Request Data or eXtra
   95              state <= doCarExt;
   96            elsif (RqData = '1') then
   97              RDX   <= "10";              -- Request Data or eXtra
   98              state <= doData;
   99            else
  100              RDX   <= "00";              -- Request Data or eXtra
  101              state <= doIdle1;
  102            end if;
  103          when doCarExt =>
  104            CDS   <= "100";               -- CAV, DAV, Select eXtra
  105            RDX   <= "00";                -- Request Data or eXtra
  106            state <= doEData;
  107          when doEData =>
  108            CDS   <= "011";               -- CAV, DAV, Select eXtra
  109            Cycle <= Cycle + 1;
  110            if (RqData = '1') then
  111              RDX   <= "10";              -- Request Data or eXtra
  112              state <= doData;
  113            else
  114              RDX   <= "00";              -- Request Data or eXtra
  115              state <= doIdle1;   -- Idles first (before next "flags")
  116            end if;
  117          when others =>
  118            CDS   <= "000";               -- CAV, DAV, Select eXtra
  119            RDX   <= "00";                -- Request Data or eXtra
  120            state <= doIdle1;
  121          end case;
  122        else
  123          RDX    <= "00";                 -- no Request Data or eXtra
  124          Toggle <= '1';
  125        end if;
  126      end if;
  127    end process;
  128  
  129  end architecture a0 ; -- of SndWords
  130  
  131