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

module
  axis_to_memory
  #(
    W, // data width in bits
    A, // address width in bits
    P = 1 // pipeline delay
  )
  (
    axis_if        axis_ar,
    axis_if        axis_r,
    output         wr,
    output [A-1:0] addr,
    output [W-1:0] din,
    input  [W-1:0] dout,
    input          aclk,
    input          aresetn
  );

  // --------------------------------------------------------------------
  localparam CW = ($clog2(P) == 0) ? 1 : $clog2(P);
  localparam D = 2 ** CW;
  localparam UB = $clog2(D);

  // --------------------------------------------------------------------
  reg [P-1:0] pipeline;
  wire ar = axis_ar.tready & axis_ar.tvalid;
  wire rd_ready = pipeline[0];
  wire bypass;

  generate
    if(P > 1) begin: pipeline_gen
      always_ff @(posedge aclk)
        if(~aresetn)
          pipeline <= 0;
        else
          pipeline <= {ar, pipeline[P-1:1]};
    end
    else begin: min_pipeline_gen // P == 1
      always_ff @(posedge aclk)
        if(~aresetn)
          pipeline <= 0;
        else
          pipeline <= ar;
    end
  endgenerate

  // --------------------------------------------------------------------
  wire          wr_full;
  wire [W-1:0]  wr_data = dout;
  wire          wr_en = bypass ? 0 : rd_ready;
  wire          rd_empty;
  wire [W-1:0]  rd_data;
  wire          rd_en = axis_r.tready & axis_r.tvalid & ~bypass;
  wire [UB:0]   count;

  sync_fifo #(W, D) fifo_i(.clk(aclk), .reset(~aresetn), .*);

  // --------------------------------------------------------------------
  // assign bypass = rd_empty & (count != 0) & rd_ready;
  assign bypass = 0;

  // // --------------------------------------------------------------------
  // logic [$clog2($bits(pipeline)+1)-1:0] in_pipeline;

  // always_comb begin
    // in_pipeline = '0;

    // foreach(pipeline[idx]) begin
      // in_pipeline += pipeline[idx];
    // end
  // end

  // --------------------------------------------------------------------
  reg [$clog2($bits(pipeline)+1)-1:0] pipeline_count;
  reg [$clog2($bits(pipeline)+1)-1:0] next_pipeline_count;

  always_comb
    case({rd_ready, ar})
      2'b0_0: next_pipeline_count = pipeline_count;
      2'b0_1: next_pipeline_count = pipeline_count + 1;
      2'b1_0: next_pipeline_count = pipeline_count - 1;
      2'b1_1: next_pipeline_count = pipeline_count;
  endcase

  always_ff @(posedge aclk)
    if(~aresetn)
      pipeline_count <= 0;
    else
      pipeline_count <= next_pipeline_count;

  // --------------------------------------------------------------------
  assign axis_ar.tready = (pipeline_count + count < D) | rd_en;
  assign axis_r.tdata = bypass ? dout : rd_data;
  assign axis_r.tlast = 1;
  assign axis_r.tvalid = ~rd_empty | bypass;

  // --------------------------------------------------------------------
  assign wr = 0;
  // assign addr = axis_ar.tdata;

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