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Updated 5/28/13

SystemVerilog Errata

SystemVerilog for Verification, Second Edition, Errata

Thank you to everyone who has sent me the mistakes they found in my book, SystemVerilog for Verification, first edition. Like a hardware project, the book has "bugs". Both hardware and books should be verified by someone other than the person who created it. Now if I can only figure out how to perform constrained random testing of text...

This page will show any functional mistakes in the SECOND EDITION of the book. Code that does not work, explanations that are incorrect, etc. Simple typos and bad English are not included. The apostrophes point left and right in some examples - blame FrameMaker!

Remember - if you are the first to find a mistake in a chapter, you get a free, autographed copy. There are 12 chapters, so that is 12 copies. This offer is open only to residents of the USA, as overseas shipping is too high. You must have a legal copy of the book.

Chapter 1 Verification Guidelines


Chapter 2 Data Types

  • Page 29, Sample 2.7, the last line should be:
    descend = '{default:1}; // Sets all elements to 1
    Also, delete the last sentence of the previous paragraph.
  • Page 30, Sample 2.9, the fourth-to-last line should be:
    md = '{'{9, 8, 7}, '{3{
  • Page 32, Sample 2.13, the last three lines should be:
      $display("src[1:4] %s dst[1:4]",
               (src[1:4] == dst[1:4]) ? "==" : "!=");
  • Page 35, the paragraph after Sample 2-17 should say:
    Line F allocates 20 new elements, and copies the existing 5 elements of dyn to the beginning of the array.
  • Page 39, Sample 2.21, the first few lines should be:
    initial begin
       bit [63:0] assoc[
    bit [63:0]], idx = 1;
  • Page 42, 2nd paragraph, last sentence:
    just change the type of rand_idx to string
  • Page 51, Sample 2-38, the sixth line should have a shorter constant:
    my_struct_s st = '{32'haaaa_aaaa,
  • Page 55, Section 2.12:
    Before enumerated types, you had to use text macros. Their global scope is too broad, and, in most cases, are not visible in the debugger.
  • Page 57, the third to last sentence should read:
    This is similar to a for-loop that tries to step through the values 0 to 3 with an index declared as bit [1:0].
  • Page 58, Sample 2.51, the second to last line should be:
    $display("C2 is %0d / %s", c2,;
  • Page 60, Sample 2.53, in the 6th to last line, shortened the task name to:
    my_log($psprintf("%s %5d", s, 42));

Chapter 3 Procedural Statements and Routines

  • Page 70, Sample 3.12, the last three lines should be:
        checksum ^= a[i];
      $display("The array checksum is %0d",
  • Page 75, Sample 3.25:
    logic [7:0] local_addr;
    local_addr = addr << 2; // Bug
  • Page 77, section 3.7.4, the first sentence should be:
    "The system task $time returns an integer scaled to the time unit of the current module, ..."

Chapter 4 Connecting the Testbench and Design

  • Page 87: ignore the [Au3] note in the right margin.
  • Page 91, Sample 4.15, the nineth line should be:
      assign ifc.w = local_wire;
  • Page 98, Figure 4.6, the bottom signal should be labelled: TEST arbif.cb.grant
  • Page 105 and 106, Sample 4.32. Module instances outside of a module are not legal according to the latest interpretation of the LRM, so the explanation at the bottom of 105 and sample 4.32 are very different.

    "Sample 4-32 shows a program that is instantiated in a module that is implictly instantiated in the top-level scope. The program can use a relative or absolute reference to the clk signal in the module. You may want to use a macro to hold the hierarchical path so that when the path changes, you only have to change one piece of code. The LRM does not allow explicit instantiation of modules at the top-level scope."
    Sample 4.32 Cross-module references with $root
    module top;
      bit clk;
      test t1(.*);

    `define TOP $root.
    program automatic test;
      initial begin
        // Absolute reference
        $display("clk=%b", $root.
        $display("clk=%b", `TOP.clk);    // With macro

        // Relative reference

Chapter 5 Basic Object Oriented Programming

  • Page 133, section 5.7, swapped words. The sentence should read:
    A SystemVerilog handle can only point to objects of one type, so they are called "type-safe."
  • Page 149, Sample 5.25, last line should be:
    endfunction : create
  • Page 152, Sample 5.30, misspelling in second comment:
    // Construct a new Statistics object
  • Page 155, Sample 5.35, wrong copy on line 5!
    dst = src.copy();

Chapter 6 Randomization

  • Page 167, last paragraph, second sentance should read:
    In Sample 6.2, since there are no random variables, randomize() just checks the value of age to see if it is in the bounds specified by the constraint c_teenager.
  • Page 168, Sample 6-3, 12th line should be:
        dst inside {[CONGEST_ADDR-10:CONGEST_ADDR+10]};
  • Page 171, Sample 6.10, the last two constraints are missing ']':
    b inside ([$:4], [20:$]}; // 0 <= b <= 4 || 20 <= b <= 127
    e inside ([$:4], [20:$
    ]}; // 0 <= e <= 4 || 20 <= e <= 63
  • Page 173, Sample 6.14, the 12th line should be:
    repeat (20_000)
  • Page 188, Sample 6.34, first line should be:
    typedef enum {READ8, READ16, READ32} read_e;
  • Page 193, Sample 6.40, need to include the class definition in the program block.
    automatic test;
    `include ""
    constraint Packet::c_external {length == 1; }
  • Page 212, Sample 6-70, third line:
    atm_gen new_gen; // New ATM generator
  • Page 214, Sample 6.72, the build() method should be:
    function void build();
      foreach (gen[i]) begin
        // Build all components
        gen[i] = new();
        drv[i] = new();
        if (cfg.is_100[i])

Chapter 7 Threads and Interprocess Communication

  • Page 236, Sample 7-26, the 3rd to last line should not have () as triggered is an event property, not a method.
    wait(gen_done.triggered); // Wait for finish
  • Page 237, Sample 7-27 and 7-28, the create / start loop should pass the event to the constructor, not the run method.
    initial begin
      foreach (gen[i]) begin
        gen[i] = new
    (done[i]); // Create N generators
    (); // Start them running
  • Page 249, Sample 7.41, after the class declaration:
      endclass : Consumer

      Producer p;
      Consumer c;
  • Page 250, Sample 7.43, add some declarations:
    program automatic mbx_evt;
    mailbox mbx;
  • Page 251, Sample 7.44, after the class declaration:
      endclass : Consumer

      Producer p;
      Consumer c;

    initial begin
        mbx = new();
  • Page 252, Sample 7.46, same as previous:
      endclass : Consumer

      Producer p;
      Consumer c;

    initial begin
        mbx = new();
        rtn = new();
  • Page 255, Sample 7-49, second line, run_for_n_trans needs to be rand:
      rand bit [31:0] run_for_n_trans;

Chapter 8 Advanced Object Oriented Programming and Testbench Guidelines

  • Page 264, Sample 8.4, the last assignment should be:
      ifc.cb.src <= tr.src;
  • Page 282, Sample 8-25, first line should be:
    class BadTr extends Transaction;
  • Page 282, second to last paragraph. The original wording is unclear, so try the following:
    OOP languages such as SystemVerilog have two constructs to allow you to build a shareable base class. The first is an abstract class, which is a class that can be extended, but not instantiated directly. It is defined with the virtual keyword. The second is a pure virtual method, which is a prototype without a body. A class extended from an abstract class can only be instantiated if all virtual methods have bodies. The pure keyword specifies that a method declaration is a prototype, and not just an empty virtual method. Lastly, pure virtual methods can only be declared in an abstract class. An abstract class can contain pure virtual methods, virtual methods with and without a body, and non-virtual methods. Note that if you define a virtual method without a body, you can call it, but it just immediately returns.
  • Page 286, last line should be:
    This is because a typical callback uses only one of them. If a class has even one pure virtual method without an implementation, OOP rules won't allow you to instantiate it.
  • Page 288, Sample 8.32, the correct scoreboard function should be save_expected:
      function void save_expected(input Transaction tr);

Chapter 9 Functional Coverage

  • Page 303, Sample 9-2, the transaction must be declared before the covergroup.
    Transaction tr;

    covergroup CovPort;
      coverpoint tr.port; // Measure coverage

    initial begin
      CovPort ck;
  • Page 311, Sample 9-11, the third line should have "option", not "options".
      { option.auto_bin_max = 2; } // Divide into 2 bins
  • Page 312, Sample 9-13, the second line should have "option", not "options".
      option.auto_bin_max = 2; // Affects port & data
  • Page 312, Section 9.6.4, the last sentence of the first paragraph should be:
    For example, sampling a 3-bit header length (0:7) plus a 4-bit payload length (0:15) creates only 24 or 16 bins, which may not be enough if your transactions can actually be from 0 to 22 bytes long.
  • Page 318, Sample 9-27, the fourth line should have "option", not "options".
      option.auto_bin_max = 4; // 0:1, 2:3, 4:5, 6:7
  • Page 318, Samples 9-26, -27, and -28, the third from last line should not have any square brackets:
      ignore_bins hi = {6,7}; // Ignore upper 2 values
  • Page 321, Section 9.7.2, final line:
    other values, 1 or 3, are not seen.

Chapter 10 Advanced Interfaces

  • Page 344, Sample 10.19, the foreach loop has two mistakes:
      foreach (driver[i]) begin
        int j = i
    ; // Missing semicolon
    end // Missing end

Chapter 11 A Complete SystemVerilog Testbench

  • Page 357, sample 11-6, the 14th line should be:
    cfg = new(numRx, numTx);
    Otherwise this is accessing program-level parameters instead of local variables.
  • Page 363, sample 11-12, the 14th line should be:
    $write("%sConfig: numRx=%0d, numTx=%0d, nCells=%0d (", prefix, numRx, numRx, nCells);

Chapter 12 Interfacing with C

  • Page 383, Sample 12.4, the second line should be:
    output int sum
  • Page 387, last paragraph, change the third sentance to:
    If you need more than one instance of a module that calls C code, the C code needs to store its variables somewhere other than in static variables.
  • Page 390, Figure 12-1, the bit labels 39:31 should be 39:32.
  • Page 391, Figure 12-1, the bit labels 39:31 should be 39:32.
  • Page 402, section 12.5.3, remove the sentence:
    In Sample 12.24, the C code assumed that the array had five elements, numbered 0.4.


  • Page 421, the VMM was copyrighted 2006, even though it was published in 2005.


Thanks to Alok Agrawal, Richard Byrne, Ching-Chi Chang, Yan Chen, Cliff Cummings, Ed D'Avignon, Xiaobin Chu, Jaikumar Devaraj, Cory Dearing, Tony Hsu, Dave Hamilton, Pochang Hsu, Ken Imboden, Brian Jensen, Jim Kann, John Keen, Amirtha Kasturi, Devendra Kumar, John Mcandrew, Chet Nibby, Eric Ohana, Simon Peter, Duc Pham, Hani Poly, Robert Qi, Ranbir Rana, Ramakrishna Reddy, Dan Shupe, Alex Seibulescu, Neill Shepherd, Greg Tumbush, Daniel Wei, Randy Wetzel, Jeff Yang, Dan Yingling and Hualong Zhao for their help.
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