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The SimulatorCallback Interface

Overview

Details

  // Called each time the simulator resets
  public void simulatorReset();

  // Called each clock step after the circuit settles
  public void simulatorUpdate(int cycle, int phase);

  // Called each time the JHDL system deems a refresh of all
  // GUI elements is warranted (i.e. after a simulation run which
  // could be of multiple cycles)
  public void simulatorRefresh(int cycle, int phase);

Debug Printing With The SimulatorCallback Interface

///////////////////////////////////////////////////////////////////////
import byucc.jhdl.base.*;
import byucc.jhdl.Logic.*;

// Class name is TestSimCallback.  It implements the SimulatorCallback interface...
public class TestSimCallback extends Logic implements SimulatorCallback {

  public static CellInterface[] cell_interface = {
    out ( "q", "WID" ),
    param ("WID", INTEGER),
  };

  Wire q;

  // This is just the constructor as normal
  public TestSimCallback(
           Node parent,
           Wire q,
           String instanceName
         ) {
    super(parent, instanceName);
    bind("WID", q.getWidth());
    this.q = connect("q", q);

    // Build a simple counter...
    Wire s = wire(q.getWidth(), "sum");
    add_o(q, constant(q.getWidth(), 1), s, "addn");
    reg_o( s, q, "cntOut");
  }

  // The SimulatorCallback interface stuff follows


  public void simulatorReset() {
  }

  public void simulatorRefresh(int cycle, int phase) {
  }

  // Print results to screen as well
  public void simulatorUpdate(int cycle, int phase) {
    System.out.println("Cycle = " + cycle +
                       ", Phase = " + phase +
                       ": " + q.get(this));
  }
}
///////////////////////////////////////////////////////////////////////

This same capability has been successfully used to do complex validation of stream-based DSP designs that would be extremely difficult to do by looking at waveforms. For example, consider a system where data arrives infrequently and must be converted from serial to parallel format before any other meaningful processing occurs. The simulatorUpdate() method can test the circuit's internal signals each clock cycle and print out key circuit values only on clock cycles when something of interest occurs (a conversion has completed). In addition, this output can be printed in a format that a tool such as Matlab could read in and post-process or plot. It often makes sense to also convert the bits in the circuit to their equivalent floating point representations for viewing (the JAB tools have only integer types available for display).

Creating Self-Validating Designs

Creating Custom Graphical Browser Elements

  // The SimulatorCallback interface stuff follows
  TestFrame tf;        // Frame to hold cycle count in GUI

  public void simulatorReset() {
    // Create a testFrame if one doesn't exist yet
    if (tf != null)
      tf.dispose();
    tf = new TestFrame();
  }

  // Update information in TestFrame
  public void simulatorRefresh(int cycle, int phase) {
    tf.updateValues(q.get(this));
  }

  // Print results to screen as well
  public void simulatorUpdate(int cycle, int phase) {
    System.out.println("Cycle = " + cycle +
                       ", Step = " + step +
                       ": " + q.get(this));
  }
}

The Complete Example

tb_TestSimCallback.java

TestSimulatorCallback.java

TestFrame.java

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Reproduction in whole or in part in any form or medium without express permission of Brigham Young University is prohibited.

Documentation Revision: $Date: 2003/04/24 14:15:12 $