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.

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();