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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  wb_master_model.v                                           ////

////                                                              ////

////  This file is part of the SPI IP core project                ////

////  http://www.opencores.org/projects/spi/                      ////

////                                                              ////

////  Author(s):                                                  ////

////      - Simon Srot (simons@opencores.org)                     ////

////                                                              ////

////  Based on:                                                   ////

////      - i2c/bench/verilog/wb_master_model.v                   ////

////        Copyright (C) 2001 Richard Herveille                  ////

////                                                              ////

////  All additional information is avaliable in the Readme.txt   ////

////  file.                                                       ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2002 Authors                                   ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source 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 Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

`include "timescale.v"

module wb_master_model(clk, rst, adr, din, dout, cyc, stb, we, sel, ack, err, rty);

  parameter dwidth = 32;

  parameter awidth = 32;

  input                  clk, rst;

  output [awidth   -1:0] adr;

  input  [dwidth   -1:0] din;

  output [dwidth   -1:0] dout;

  output                 cyc, stb;

  output                 we;

  output [dwidth/8 -1:0] sel;

  input                  ack, err, rty;

  // Internal signals

  reg    [awidth   -1:0] adr;

  reg    [dwidth   -1:0] dout;

  reg                    cyc, stb;

  reg                    we;

  reg    [dwidth/8 -1:0] sel;

  reg    [dwidth   -1:0] q;

  // Memory Logic

  initial

    begin

      adr  = {awidth{1'bx}};

      dout = {dwidth{1'bx}};

      cyc  = 1'b0;

      stb  = 1'bx;

      we   = 1'hx;

      sel  = {dwidth/8{1'bx}};

      #1;

    end

  // Wishbone write cycle

  task wb_write;

    input   delay;

    integer delay;

    input [awidth -1:0] a;

    input [dwidth -1:0] d;

    begin

      // wait initial delay

      repeat(delay) @(posedge clk);

      // assert wishbone signal

      #1;

      adr  = a;

      dout = d;

      cyc  = 1'b1;

      stb  = 1'b1;

      we   = 1'b1;

      sel  = {dwidth/8{1'b1}};

      @(posedge clk);

      // wait for acknowledge from slave

      while(~ack) @(posedge clk);

      // negate wishbone signals

      #1;

      cyc  = 1'b0;

      stb  = 1'bx;

      adr  = {awidth{1'bx}};

      dout = {dwidth{1'bx}};

      we   = 1'hx;

      sel  = {dwidth/8{1'bx}};

    end

  endtask

  // Wishbone read cycle

  task wb_read;

    input   delay;

    integer delay;

    input  [awidth -1:0]  a;

    output  [dwidth -1:0] d;

    begin

      // wait initial delay

      repeat(delay) @(posedge clk);

      // assert wishbone signals

      #1;

      adr  = a;

      dout = {dwidth{1'bx}};

      cyc  = 1'b1;

      stb  = 1'b1;

      we   = 1'b0;

      sel  = {dwidth/8{1'b1}};

      @(posedge clk);

      // wait for acknowledge from slave

      while(~ack) @(posedge clk);

      // negate wishbone signals

      #1;

      cyc  = 1'b0;

      stb  = 1'bx;

      adr  = {awidth{1'bx}};

      dout = {dwidth{1'bx}};

      we   = 1'hx;

      sel  = {dwidth/8{1'bx}};

      d    = din;

    end

  endtask

  // Wishbone compare cycle (read data from location and compare with expected data)

  task wb_cmp;

    input   delay;

    integer delay;

    input [awidth -1:0] a;

    input [dwidth -1:0] d_exp;

    begin

      wb_read (delay, a, q);

    if (d_exp !== q)

      $display("Data compare error. Received %h, expected %h at time %t", q, d_exp, $time);

    end

  endtask

endmodule