// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
// In this HDL repository, there are many different and unique modules, consisting
// of various HDL (Verilog or VHDL) components. The individual modules are
// developed independently, and may be accompanied by separate and unique license
// terms.
//
// The user should read each of these license terms, and understand the
// freedoms and responsibilities that he or she has by using this source/core.
//
// This core 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.
//
// Redistribution and use of source or resulting binaries, with or without modification
// of this file, are permitted under one of the following two license terms:
//
//   1. The GNU General Public License version 2 as published by the
//      Free Software Foundation, which can be found in the top level directory
//      of this repository (LICENSE_GPL2), and also online at:
//      <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
//
// OR
//
//   2. An ADI specific BSD license, which can be found in the top level directory
//      of this repository (LICENSE_ADIBSD), and also on-line at:
//      https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
//      This will allow to generate bit files and not release the source code,
//      as long as it attaches to an ADI device.
//
// ***************************************************************************
// ***************************************************************************

`timescale 1ns/100ps

module dest_fifo_inf #(

  parameter ID_WIDTH = 3,
  parameter DATA_WIDTH = 64,
  parameter BEATS_PER_BURST_WIDTH = 4
) (
  input clk,
  input resetn,

  input enable,
  output enabled,

  input req_valid,
  output req_ready,

  output [ID_WIDTH-1:0] response_id,
  output reg [ID_WIDTH-1:0] data_id = 'h0,
  input data_eot,
  input response_eot,

  input en,
  output reg [DATA_WIDTH-1:0] dout,
  output reg valid,
  output reg underflow,

  output xfer_req,

  output fifo_ready,
  input fifo_valid,
  input [DATA_WIDTH-1:0] fifo_data,
  input fifo_last,

  output response_valid,
  input response_ready,
  output response_resp_eot,
  output [1:0] response_resp
);

`include "inc_id.vh"

  reg active = 1'b0;

  // Last beat of the burst
  wire fifo_last_beat;
  // Last beat of the segment
  wire fifo_eot_beat;

  assign enabled = enable;
  assign fifo_ready = en & (fifo_valid | ~enable);

  // fifo_last == 1'b1 implies fifo_valid == 1'b1
  assign fifo_last_beat = fifo_ready & fifo_last;
  assign fifo_eot_beat = fifo_last_beat & data_eot;

  assign req_ready = fifo_eot_beat | ~active;
  assign xfer_req = active;

  always @(posedge clk) begin
    if (en) begin
      dout <= fifo_valid ? fifo_data : {DATA_WIDTH{1'b0}};
      valid <= fifo_valid & enable;
      underflow <= ~(fifo_valid & enable);
    end else begin
      valid <= 1'b0;
      underflow <= 1'b0;
    end
  end

  always @(posedge clk) begin
    if (resetn == 1'b0) begin
      data_id <= 'h00;
    end else if (fifo_last_beat == 1'b1) begin
      data_id <= inc_id(data_id);
    end
  end

  always @(posedge clk) begin
    if (resetn == 1'b0) begin
      active <= 1'b0;
    end else if (req_valid == 1'b1) begin
      active <= 1'b1;
    end else if (fifo_eot_beat == 1'b1) begin
      active <= 1'b0;
    end
  end

  response_generator #(
    .ID_WIDTH(ID_WIDTH)
  ) i_response_generator (
    .clk(clk),
    .resetn(resetn),

    .enable(enable),
    .enabled(),

    .request_id(data_id),
    .response_id(response_id),

    .eot(response_eot),

    .resp_valid(response_valid),
    .resp_ready(response_ready),
    .resp_eot(response_resp_eot),
    .resp_resp(response_resp));

endmodule