Subversion Repositories srdydrdy_lib

module ring_arb

  (

   input        clk,

   input        reset,

   input [`NUM_PORTS-1:0] rarb_req,

   output reg [`NUM_PORTS-1:0] rarb_ack

   );

  integer                      i;

  reg [`NUM_PORTS-1:0]         nxt_rarb_ack;

  //reg [$clog2(`NUM_PORTS)-1:0] nxt_ack;

  function [`NUM_PORTS-1:0] nxt_grant;

    input [`NUM_PORTS-1:0] cur_grant;

    input [`NUM_PORTS-1:0] cur_req;

    reg [`NUM_PORTS-1:0]   msk_req;

    reg [`NUM_PORTS-1:0]   tmp_grant;

    begin

      msk_req = cur_req & ~((cur_grant - 1) | cur_grant);

      tmp_grant = msk_req & (~msk_req + 1);

      if (msk_req != 0)

        nxt_grant = tmp_grant;

      else

        nxt_grant = cur_req & (~cur_req + 1);

    end

  endfunction // if

  //assign nxt_rarb_ack = nxt_grant (rarb_ack, rarb_req);

  always @*

    begin

      nxt_rarb_ack = rarb_ack;

      if (rarb_req == 0)

        nxt_rarb_ack = 0;

      else if ((rarb_req & rarb_ack) == 0)

        begin

          nxt_rarb_ack = nxt_grant (rarb_ack, rarb_req);

/* -----\/----- EXCLUDED -----\/-----

          nxt_ack = 0;

          for (i=`NUM_PORTS; i>0; i=i-1)

            if (rarb_req[i-1])

              nxt_ack = i-1;

          nxt_rarb_ack = 1 << nxt_ack;

 -----/\----- EXCLUDED -----/\----- */

        end

    end // always @ *

  always @(posedge clk)

    begin

      if (reset)

        rarb_ack <= #1 0;

      else if ((rarb_req & rarb_ack) == 0)

        rarb_ack <= #1 nxt_rarb_ack;

    end

endmodule // ring_arb