// ***************************************************************************
// ***************************************************************************
// Copyright (C) 2014-2023 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.
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// 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>
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// 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/main/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 util_mfifo #(

  parameter   NUM_OF_CHANNELS = 4,
  parameter   DIN_DATA_WIDTH = 32,
  parameter   ADDRESS_WIDTH = 8
) (

  // d-in interface

  input                   din_rst,
  input                   din_clk,
  input                   din_valid,
  input       [DIN_DATA_WIDTH-1:0]  din_data_0,
  input       [DIN_DATA_WIDTH-1:0]  din_data_1,
  input       [DIN_DATA_WIDTH-1:0]  din_data_2,
  input       [DIN_DATA_WIDTH-1:0]  din_data_3,
  input       [DIN_DATA_WIDTH-1:0]  din_data_4,
  input       [DIN_DATA_WIDTH-1:0]  din_data_5,
  input       [DIN_DATA_WIDTH-1:0]  din_data_6,
  input       [DIN_DATA_WIDTH-1:0]  din_data_7,

  // d-out interface

  input                   dout_rst,
  input                   dout_clk,
  output  reg             dout_valid,
  output      [15:0]      dout_data_0,
  output      [15:0]      dout_data_1,
  output      [15:0]      dout_data_2,
  output      [15:0]      dout_data_3,
  output      [15:0]      dout_data_4,
  output      [15:0]      dout_data_5,
  output      [15:0]      dout_data_6,
  output      [15:0]      dout_data_7
);

  // internal registers

  reg                                 din_dout_toggle_m1 = 'd0;
  reg                                 din_dout_toggle_m2 = 'd0;
  reg                                 din_dout_toggle_m3 = 'd0;
  reg                                 din_wr = 'd0;
  reg     [(ADDRESS_WIDTH-1):0]       din_waddr = 'd0;
  reg                                 din_enable = 'd0;
  reg                                 din_toggle = 'd0;
  reg                                 dout_din_toggle_m1 = 'd0;
  reg                                 dout_din_toggle_m2 = 'd0;
  reg                                 dout_din_toggle_m3 = 'd0;
  reg     [ 4:0]                      dout_cnt = 'd0;
  reg                                 dout_ld = 'd0;
  reg                                 dout_ld_d = 'd0;
  reg     [(ADDRESS_WIDTH-1):0]       dout_raddr = 'd0;
  reg                                 dout_enable = 'd0;
  reg                                 dout_toggle = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_0 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_1 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_2 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_3 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_4 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_5 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_6 = 'd0;
  reg     [(DIN_DATA_WIDTH-1):0]      dout_rdata_7 = 'd0;

  // internal signals

  wire    [(DIN_DATA_WIDTH-1):0]      din_wdata_s[0:7];
  wire                                din_waddr_max_s;
  wire                                din_dout_toggle_s;
  wire                                dout_raddr_max_s;
  wire                                dout_rd_s;
  wire                                dout_din_toggle_s;
  wire    [(DIN_DATA_WIDTH-1):0]      dout_rdata_s[0:7];

  // variables

  genvar                              n;

  // write interface

  assign din_wdata_s[7] = din_data_7;
  assign din_wdata_s[6] = din_data_6;
  assign din_wdata_s[5] = din_data_5;
  assign din_wdata_s[4] = din_data_4;
  assign din_wdata_s[3] = din_data_3;
  assign din_wdata_s[2] = din_data_2;
  assign din_wdata_s[1] = din_data_1;
  assign din_wdata_s[0] = din_data_0;
  assign din_waddr_max_s = & din_waddr;
  assign din_dout_toggle_s = din_dout_toggle_m3 ^ din_dout_toggle_m2;

  always @(posedge din_clk or posedge din_rst) begin
    if (din_rst == 1'b1) begin
      din_dout_toggle_m1 <= 1'd0;
      din_dout_toggle_m2 <= 1'd0;
      din_dout_toggle_m3 <= 1'd0;
      din_wr <= 1'd0;
      din_waddr <= 'd0;
      din_enable <= 1'd0;
      din_toggle <= 1'd0;
    end else begin
      din_dout_toggle_m1 <= dout_toggle;
      din_dout_toggle_m2 <= din_dout_toggle_m1;
      din_dout_toggle_m3 <= din_dout_toggle_m2;
      din_wr <= din_valid & din_enable;
      if (din_dout_toggle_s == 1'b1) begin
        din_waddr <= 'd0;
        din_enable <= 1'b1;
      end else if (din_wr == 1'b1) begin
        din_waddr <= din_waddr + 1'b1;
        if (din_waddr_max_s == 1) begin
          din_enable <= 1'b0;
        end
      end
      if ((din_wr == 1'b1) && (din_waddr_max_s == 1)) begin
        din_toggle <= ~din_toggle;
      end
    end
  end

  // read interface

  assign dout_raddr_max_s = & dout_raddr;
  assign dout_rd_s = (dout_cnt == 5'd0) ? dout_enable : 1'b0;
  assign dout_din_toggle_s = dout_din_toggle_m3 ^ dout_din_toggle_m2;

  always @(posedge dout_clk or posedge dout_rst) begin
    if (dout_rst == 1'b1) begin
      dout_din_toggle_m1 <= 1'd0;
      dout_din_toggle_m2 <= 1'd0;
      dout_din_toggle_m3 <= 1'd0;
      dout_cnt <= 'd0;
      dout_ld <= 'd0;
      dout_ld_d <= 'd0;
      dout_raddr <= 'd0;
      dout_enable <= 1'd0;
      dout_toggle <= 1'd1;
    end else begin
      dout_din_toggle_m1 <= din_toggle;
      dout_din_toggle_m2 <= dout_din_toggle_m1;
      dout_din_toggle_m3 <= dout_din_toggle_m2;
      if ((dout_din_toggle_s == 1'b1) || (dout_cnt >= ((DIN_DATA_WIDTH/16) - 1))) begin
        dout_cnt <= 'd0;
      end else begin
        dout_cnt <= dout_cnt + 1'b1;
      end
      dout_ld <= | dout_cnt;
      dout_ld_d <= dout_ld;
      if (dout_din_toggle_s == 1'b1) begin
        dout_raddr <= 'd0;
        dout_enable <= 1'b1;
      end else if (dout_rd_s == 1'b1) begin
        dout_raddr <= dout_raddr + 1'b1;
        if (dout_raddr_max_s == 1'b1) begin
          dout_enable <= 1'b0;
        end
      end
      if ((dout_rd_s == 1'b1) && (dout_raddr_max_s == 1'b1)) begin
        dout_toggle <= ~dout_toggle;
      end
    end
  end

  always @(posedge dout_clk or posedge dout_rst) begin
    if (dout_rst == 1'b1) begin
      dout_valid <= 'd0;
      dout_rdata_0 <= 'd0;
      dout_rdata_1 <= 'd0;
      dout_rdata_2 <= 'd0;
      dout_rdata_3 <= 'd0;
      dout_rdata_4 <= 'd0;
      dout_rdata_5 <= 'd0;
      dout_rdata_6 <= 'd0;
      dout_rdata_7 <= 'd0;
    end else begin
      if (dout_ld_d == 1'b0) begin
        dout_valid <= dout_enable;
        dout_rdata_0 <= dout_rdata_s[0];
        dout_rdata_1 <= dout_rdata_s[1];
        dout_rdata_2 <= dout_rdata_s[2];
        dout_rdata_3 <= dout_rdata_s[3];
        dout_rdata_4 <= dout_rdata_s[4];
        dout_rdata_5 <= dout_rdata_s[5];
        dout_rdata_6 <= dout_rdata_s[6];
        dout_rdata_7 <= dout_rdata_s[7];
      end else begin
        dout_valid <= dout_valid;
        dout_rdata_0 <= {16'd0, dout_rdata_0[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_1 <= {16'd0, dout_rdata_1[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_2 <= {16'd0, dout_rdata_2[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_3 <= {16'd0, dout_rdata_3[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_4 <= {16'd0, dout_rdata_4[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_5 <= {16'd0, dout_rdata_5[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_6 <= {16'd0, dout_rdata_6[(DIN_DATA_WIDTH-1):16]};
        dout_rdata_7 <= {16'd0, dout_rdata_7[(DIN_DATA_WIDTH-1):16]};
      end
    end
  end

  assign dout_data_0 = dout_rdata_0[15:0];
  assign dout_data_1 = dout_rdata_1[15:0];
  assign dout_data_2 = dout_rdata_2[15:0];
  assign dout_data_3 = dout_rdata_3[15:0];
  assign dout_data_4 = dout_rdata_4[15:0];
  assign dout_data_5 = dout_rdata_5[15:0];
  assign dout_data_6 = dout_rdata_6[15:0];
  assign dout_data_7 = dout_rdata_7[15:0];

  // instantiations

  generate

  if (NUM_OF_CHANNELS < 8) begin
  for (n = NUM_OF_CHANNELS; n < 8; n = n + 1) begin: g_channels_unused
  assign dout_rdata_s[n] = 'd0;
  end
  end

  for (n = 0; n < NUM_OF_CHANNELS; n = n + 1) begin: g_channels
  ad_mem #(
    .ADDRESS_WIDTH (ADDRESS_WIDTH),
    .DATA_WIDTH (DIN_DATA_WIDTH)
  ) i_mem (
    .clka (din_clk),
    .wea (din_wr),
    .addra (din_waddr),
    .dina (din_wdata_s[n]),
    .clkb (dout_clk),
    .reb (1'b1),
    .addrb (dout_raddr),
    .doutb (dout_rdata_s[n]));
  end

  endgenerate

endmodule