// ***************************************************************************
// ***************************************************************************
// Copyright 2013(c) Analog Devices, Inc.
//  Author: Lars-Peter Clausen <lars@metafoo.de>
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
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//       from this software without specific prior written permission.
//     - The use of this software may or may not infringe the patent rights
//       of one or more patent holders.  This license does not release you
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//     - Use of the software either in source or binary form, must be run
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//    
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// ***************************************************************************
// ***************************************************************************

module dmac_2d_transfer (
  input req_aclk,
  input req_aresetn,

  input req_valid,
  output reg req_ready,

  input [31:BYTES_PER_BEAT_WIDTH_DEST] req_dest_address,
  input [31:BYTES_PER_BEAT_WIDTH_SRC] req_src_address,
  input [DMA_LENGTH_WIDTH-1:0] req_x_length,
  input [DMA_LENGTH_WIDTH-1:0] req_y_length,
  input [DMA_LENGTH_WIDTH-1:0] req_dest_stride,
  input [DMA_LENGTH_WIDTH-1:0] req_src_stride,
  input req_sync_transfer_start,
  output reg req_eot,
  
  output reg out_req_valid,
  input out_req_ready,
  output [31:BYTES_PER_BEAT_WIDTH_DEST] out_req_dest_address,
  output [31:BYTES_PER_BEAT_WIDTH_SRC] out_req_src_address,
  output [DMA_LENGTH_WIDTH-1:0] out_req_length,
  output reg out_req_sync_transfer_start,
  input out_eot
);

parameter DMA_LENGTH_WIDTH = 24;
parameter BYTES_PER_BEAT_WIDTH_SRC = 3;
parameter BYTES_PER_BEAT_WIDTH_DEST = 3;

reg [31:BYTES_PER_BEAT_WIDTH_DEST] dest_address;
reg [31:BYTES_PER_BEAT_WIDTH_SRC] src_address;
reg [DMA_LENGTH_WIDTH-1:0] x_length;
reg [DMA_LENGTH_WIDTH-1:0] y_length;
reg [DMA_LENGTH_WIDTH-1:0] dest_stride;
reg [DMA_LENGTH_WIDTH-1:0] src_stride;

reg [1:0] req_id;
reg [1:0] eot_id;
reg [3:0] last_req;

assign out_req_dest_address = dest_address;
assign out_req_src_address = src_address;
assign out_req_length = x_length;

always @(posedge req_aclk)
begin
  if (req_aresetn == 1'b0) begin
    req_id <= 2'b0;
    eot_id <= 2'b0;
    req_eot <= 1'b0;
  end else begin
    if (out_req_valid && out_req_ready) begin
      req_id <= req_id + 1'b1;
      last_req[req_id] <= y_length == 0;
    end
    req_eot <= 1'b0;
    if (out_eot) begin
      eot_id <= eot_id + 1'b1;
      req_eot <= last_req[eot_id];
    end
  end
end

always @(posedge req_aclk)
begin
  if (req_aresetn == 1'b0) begin
    dest_address <= 'h00;
    src_address <= 'h00;
    x_length <= 'h00;
    y_length <= 'h00;
    dest_stride <= 'h00;
    src_stride <= 'h00;
    req_ready <= 1'b1;
    out_req_valid <= 1'b0;
    out_req_sync_transfer_start <= 1'b0;
  end else begin
    if (req_ready) begin
      if (req_valid) begin
        dest_address <= req_dest_address;
        src_address <= req_src_address;
        x_length <= req_x_length;
        y_length <= req_y_length;
        dest_stride <= req_dest_stride;
        src_stride <= req_src_stride;
        out_req_sync_transfer_start <= req_sync_transfer_start;
        req_ready <= 1'b0;
        out_req_valid <= 1'b1;
      end
    end else begin
      if (out_req_valid && out_req_ready) begin
        dest_address <= dest_address + dest_stride[DMA_LENGTH_WIDTH-1:BYTES_PER_BEAT_WIDTH_DEST];
        src_address <= src_address + src_stride[DMA_LENGTH_WIDTH-1:BYTES_PER_BEAT_WIDTH_SRC];
        y_length <= y_length - 1'b1;
        out_req_sync_transfer_start <= 1'b0;
        if (y_length == 0) begin
          out_req_valid <= 1'b0;
          req_ready <= 1'b1;
        end
      end
    end
  end
end

endmodule
