//
// The ADI JESD204 Core is released under the following license, which is
// different than all other HDL cores in this repository.
//
// Please read this, and understand the freedoms and responsibilities you have
// by using this source code/core.
//
// The JESD204 HDL, is copyright © 2016-2017 Analog Devices Inc.
//
// This core is free software, you can use run, copy, study, change, ask
// questions about and improve this core. Distribution of source, or resulting
// binaries (including those inside an FPGA or ASIC) require you to release the
// source of the entire project (excluding the system libraries provide by the
// tools/compiler/FPGA vendor). These are the terms of the GNU General Public
// License version 2 as published by the Free Software Foundation.
//
// 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. See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License version 2
// along with this source code, and binary.  If not, see
// <http://www.gnu.org/licenses/>.
//
// Commercial licenses (with commercial support) of this JESD204 core are also
// available under terms different than the General Public License. (e.g. they
// do not require you to accompany any image (FPGA or ASIC) using the JESD204
// core with any corresponding source code.) For these alternate terms you must
// purchase a license from Analog Devices Technology Licensing Office. Users
// interested in such a license should contact jesd204-licensing@analog.com for
// more information. This commercial license is sub-licensable (if you purchase
// chips from Analog Devices, incorporate them into your PCB level product, and
// purchase a JESD204 license, end users of your product will also have a
// license to use this core in a commercial setting without releasing their
// source code).
//
// In addition, we kindly ask you to acknowledge ADI in any program, application
// or publication in which you use this JESD204 HDL core. (You are not required
// to do so; it is up to your common sense to decide whether you want to comply
// with this request or not.) For general publications, we suggest referencing :
// “The design and implementation of the JESD204 HDL Core used in this project
// is copyright © 2016-2017, Analog Devices, Inc.”
//

`timescale 1ns/100ps

// Constraints:
//   - IN_DATA_PATH_WIDTH >= OUT_DATA_PATH_WIDTH
//

module jesd204_tx_gearbox #(
  parameter IN_DATA_PATH_WIDTH = 6,
  parameter OUT_DATA_PATH_WIDTH = 4,
  parameter NUM_LANES = 1,
  parameter DEPTH = 16
) (
  input link_clk,
  input reset,
  input device_clk,
  input device_reset,
  input [NUM_LANES*IN_DATA_PATH_WIDTH*8-1:0] device_data,
  input device_lmfc_edge,
  output [NUM_LANES*OUT_DATA_PATH_WIDTH*8-1:0] link_data,
  input output_ready
);

localparam MEM_W = IN_DATA_PATH_WIDTH*8*NUM_LANES;
localparam D_LOG2 = $clog2(DEPTH);

reg [MEM_W-1:0] mem [0:DEPTH-1];
reg [D_LOG2-1:0]  in_addr ='h00;
reg [D_LOG2-1:0]  out_addr = 'b0;
reg               mem_rd_valid = 'b0;
reg [MEM_W-1:0]  mem_rd_data;

wire                mem_wr_en = 1'b1;
wire                mem_rd_en;
wire [D_LOG2-1:0]  in_out_addr;
wire [D_LOG2-1:0]  out_in_addr;
wire [NUM_LANES-1:0] unpacker_ready;
wire output_ready_sync;

sync_bits i_sync_ready (
  .in_bits(output_ready),
  .out_resetn(~device_reset),
  .out_clk(device_clk),
  .out_bits(output_ready_sync)
);

always @(posedge device_clk) begin
  if (device_lmfc_edge & ~output_ready_sync) begin
    in_addr <= 'h01;
  end else if (mem_wr_en) begin
    in_addr <= in_addr + 1;
  end
end

always @(posedge device_clk) begin
  if (mem_wr_en) begin
    mem[in_addr] <= device_data;
  end
end

assign mem_rd_en = output_ready&unpacker_ready[0];

always @(posedge link_clk) begin
  if (mem_rd_en) begin
    mem_rd_data <= mem[out_addr];
  end
  mem_rd_valid <= mem_rd_en;
end

always @(posedge link_clk) begin
  if (reset) begin
    out_addr <= 'b0;
  end else if (mem_rd_en) begin
    out_addr <= out_addr + 1;
  end
end

genvar i;
generate for (i = 0; i < NUM_LANES; i=i+1) begin: unpacker

ad_upack #(
  .I_W(IN_DATA_PATH_WIDTH),
  .O_W(OUT_DATA_PATH_WIDTH),
  .UNIT_W(8),
  .O_REG(0)
) i_ad_upack (
  .clk(link_clk),
  .reset(reset),
  .idata(mem_rd_data[i*IN_DATA_PATH_WIDTH*8+:IN_DATA_PATH_WIDTH*8]),
  .ivalid(mem_rd_valid),
  .iready(unpacker_ready[i]),

  .odata(link_data[i*OUT_DATA_PATH_WIDTH*8+:OUT_DATA_PATH_WIDTH*8]),
  .ovalid()
);

end
endgenerate

endmodule