By default, do not halt on BRK (#14)

This change introduces a new command line flag, '-b', that cause the
simulator to halt on the `BRK` instruction. By default, however, the
simulator will no longer halt on `BRK`.

As before, this behavior can be toggled in the preferences at run-time.

README.md

@@ -227,6 +227,7 @@ to specify machine type and CPU type. The options are:
   - `-machine simple`: Use the **Simple** machine type by default.
   - `-machine beneater`: Use the **BenEater** machine type by default.
   - `-rom <file>`: Use the specified file as the ROM image.
+  - `-brk`: Halt the simulator on a BRK instruction (default is to continue)
 
 ### 4.2 ROM images
 

src/main/java/com/loomcom/symon/Main.java

@@ -53,6 +53,7 @@ public class Main {
         options.addOption(new Option("m", "machine", true, "Specify machine type."));
         options.addOption(new Option("c", "cpu", true, "Specify CPU type."));
         options.addOption(new Option("r", "rom", true, "Specify ROM file."));
+        options.addOption(new Option("b", "brk", false, "Halt on BRK"));
 
         CommandLineParser parser = new DefaultParser();
 
@@ -60,6 +61,7 @@ public class Main {
             CommandLine line = parser.parse(options, args);
             InstructionTable.CpuBehavior cpuBehavior = null;
             String romFile = null;
+            boolean haltOnBreak = false;
 
             if (line.hasOption("machine")) {
                 String machine = line.getOptionValue("machine").toLowerCase(Locale.ENGLISH);
@@ -104,6 +106,10 @@ public class Main {
                 romFile = line.getOptionValue("rom");
             }
 
+            if (line.hasOption("brk")) {
+                haltOnBreak = true;
+            }
+
             while (true) {
                 if (machineClass == null) {
                     Object[] possibilities = {"Symon", "Multicomp", "Simple", "BenEater"};
@@ -132,7 +138,7 @@ public class Main {
                     cpuBehavior = InstructionTable.CpuBehavior.NMOS_6502;
                 }
 
-                final Simulator simulator = new Simulator(machineClass, cpuBehavior, romFile);
+                final Simulator simulator = new Simulator(machineClass, cpuBehavior, romFile, haltOnBreak);
 
                 SwingUtilities.invokeLater(new Runnable() {
                     @Override

src/main/java/com/loomcom/symon/Preferences.java

@@ -29,8 +29,6 @@ public interface Preferences {
 
     int DEFAULT_PROGRAM_LOAD_ADDRESS = 0x0300;
 
-    boolean DEFAULT_HALT_ON_BREAK = true;
-
     JDialog getDialog();
 
     int getProgramStartAddress();

src/main/java/com/loomcom/symon/Simulator.java

@@ -126,6 +126,8 @@ public class Simulator {
 
     private MainCommand command = MainCommand.NONE;
 
+    private boolean haltOnBreak;
+
     public enum MainCommand {
         NONE,
         SELECTMACHINE
@@ -137,16 +139,17 @@ public class Simulator {
     private static final String[] STEPS = {"1", "5", "10", "20", "50", "100"};
 
     public Simulator(Class machineClass) throws Exception {
-        this(machineClass, InstructionTable.CpuBehavior.NMOS_6502, null);
+        this(machineClass, InstructionTable.CpuBehavior.NMOS_6502, null, false);
     }
 
-    public Simulator(Class machineClass, InstructionTable.CpuBehavior cpuType, String romFile) throws Exception {
+    public Simulator(Class machineClass, InstructionTable.CpuBehavior cpuType,
+                     String romFile, boolean haltOnBreak) throws Exception {
+        this.haltOnBreak = haltOnBreak;
         this.breakpoints = new Breakpoints(this);
 
         this.machine = (Machine) machineClass.getConstructors()[0].newInstance(romFile);
         this.machine.getCpu().setBehavior(cpuType);
 
-
         // Initialize final fields in the constructor.
         this.traceLog = new TraceLog();
         this.memoryWindow = new MemoryWindow(machine.getBus());
@@ -176,7 +179,7 @@ public class Simulator {
 
         // File Chooser
         fileChooser = new JFileChooser(System.getProperty("user.dir"));
-        preferences = new PreferencesDialog(mainWindow, true);
+        preferences = new PreferencesDialog(mainWindow, true, haltOnBreak);
 
         // Panel for Console and Buttons
         JPanel consoleContainer = new JPanel();

src/main/java/com/loomcom/symon/ui/PreferencesDialog.java

@@ -42,11 +42,11 @@ public class PreferencesDialog extends Observable implements Preferences {
     private JTextField programLoadAddressField;
 
     private int programLoadAddress = DEFAULT_PROGRAM_LOAD_ADDRESS;
-    private boolean haltOnBreak = DEFAULT_HALT_ON_BREAK;
+    private boolean haltOnBreak;
 
-    public PreferencesDialog(Frame parent, boolean modal) {
+    public PreferencesDialog(Frame parent, boolean modal, boolean haltOnBreak) {
         this.dialog = new JDialog(parent, modal);
-
+        this.haltOnBreak = haltOnBreak;
         createUi();
         updateUi();
     }