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[/] [qaz_libs/] [trunk/] [axi4_stream_lib/] [src/] [axis_fanout.sv] - Rev 49

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//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2019 Authors and OPENCORES.ORG                 ////
////                                                              ////
//// 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////

module
  axis_fanout #(F)
  (
    axis_if axis_in,
    axis_if axis_out[F],
    input   aclk,
    input   aresetn
  );

  // --------------------------------------------------------------------
  wire [F-1:0] handshake;
  wire [F-1:0] stalled;
  reg [F-1:0] transfer_stalled;
  wire [F-1:0] out_tready;
  wire all_ready = &out_tready;
  wire [F-1:0] done;
  wire all_done = &done;

  // --------------------------------------------------------------------
  enum reg [1:0]
    {
      FANOUT  = 2'b01,
      STALL   = 2'b10
    } state, next_state;

  // --------------------------------------------------------------------
  always_ff @(posedge aclk)
    if(~aresetn)
      state <= FANOUT;
    else
      state <= next_state;

  // --------------------------------------------------------------------
  always_comb
    case(state)
      FANOUT:   if(~axis_in.tvalid)
                  next_state = FANOUT;
                else if(all_ready)
                  next_state = FANOUT;
                else
                  next_state = STALL;

      STALL:    if(all_done)
                  next_state = FANOUT;
                else
                  next_state = STALL;

      default:  next_state = FANOUT;
    endcase

  // --------------------------------------------------------------------
  generate
    for(genvar j = 0; j < F; j++)
    begin: tready_gen
      // --------------------------------------------------------------------
      assign handshake[j] = axis_in.tvalid &  axis_out[j].tready;
      assign stalled[j]   = axis_in.tvalid & ~axis_out[j].tready;
      assign done[j]      = ~transfer_stalled[j] | handshake[j];

      always_ff @(posedge aclk)
        if(handshake[j])
          transfer_stalled[j] <= 0;
        else if(stalled[j])
          transfer_stalled[j] <= 1;

      // --------------------------------------------------------------------
      assign out_tready[j]      = axis_out[j].tready;
      assign axis_out[j].tlast  = axis_in.tlast;
      assign axis_out[j].tuser  = axis_in.tuser;
      assign axis_out[j].tdata  = axis_in.tdata;
      assign axis_out[j].tstrb  = axis_in.tstrb;
      assign axis_out[j].tkeep  = axis_in.tkeep;
      assign axis_out[j].tid    = axis_in.tid;
      assign axis_out[j].tdest  = axis_in.tdest;
      assign axis_out[j].tvalid = (state == FANOUT) ? axis_in.tvalid : transfer_stalled[j];
    end
  endgenerate

  // --------------------------------------------------------------------
  assign axis_in.tready = (state == FANOUT) ? all_ready : (next_state == FANOUT);

// --------------------------------------------------------------------
endmodule

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