/********************************************************************** * Assigning structures a default value for all members * * Author: Stuart Sutherland * * (c) Copyright 2003, Sutherland HDL, Inc. *** ALL RIGHTS RESERVED *** * www.sutherland-hdl.com * * Used with permission in the book, "SystemVerilog for Design" *  By Stuart Sutherland, Simon Davidmann, and Peter Flake. *  Book copyright: 2003, Kluwer Academic Publishers, Norwell, MA, USA *  www.wkap.il, ISBN: 0-4020-7530-8 * * Revision History: *   1.00 15 Dec 2003 -- original code, as included in book *   1.01 10 Jul 2004 -- cleaned up comments, added expected results *                       to output messages * * Caveat: Expected results displayed for this code example are based * on an interpretation of the SystemVerilog 3.1 standard by the code * author or authors.  At the time of writing, official SystemVerilog * validation suites were not available to validate the example. * * RIGHT TO USE: This code example, or any portion thereof, may be * used and distributed without restriction, provided that this entire * comment block is included with the example. * * DISCLAIMER: THIS CODE EXAMPLE IS PROVIDED "AS IS" WITHOUT WARRANTY * OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED * TO WARRANTIES OF MERCHANTABILITY, FITNESS OR CORRECTNESS. IN NO * EVENT SHALL THE AUTHOR OR AUTHORS BE LIABLE FOR ANY DAMAGES, * INCLUDING INCIDENTAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF THE * USE OF THIS CODE. *********************************************************************/module test;  bit clock, resetN = 1;  typedef struct {    int        a, b;    byte       opcode;    bit [23:0] address;  } instruction_word_t;  instruction_word_t IW;  always @(posedge clock, negedge resetN)    if (!resetN) IW = {default:0};    else begin      //...    end  always #5 clock = ~clock;  initial begin    @(negedge clock) resetN = 0;    @(negedge clock) resetN = 1;    @(negedge clock) $display("\nIW.opcode=%h (expect 00 (hex))", IW.opcode);    @(negedge clock) IW = {default:'1}; // set all bits of all members to ones    @(negedge clock) $display("IW.opcode=%h (expect ff (hex))\n", IW.opcode);    @(negedge clock) $finish;  endendmodule