added backtracking. Is needed to determine the input signals, a output signal depends on.

src/main/java/de/neemann/digital/analyse/DependencyAnalyser.java

@@ -0,0 +1,69 @@
+package de.neemann.digital.analyse;
+
+import de.neemann.digital.core.*;
+import de.neemann.digital.draw.elements.PinException;
+import de.neemann.digital.lang.Lang;
+
+import java.util.*;
+
+import static de.neemann.digital.core.Model.MAX_LOOP_COUNTER;
+
+/**
+ * Used to analyse on which inputs a given output depends.
+ * So you only have to take into account the inputs, a given outputs
+ * depends on.
+ * Created by hneemann on 11.06.17.
+ */
+public class DependencyAnalyser {
+
+    private final HashMap<Signal, Set<ObservableValue>> sigMap;
+
+    /**
+     * Creates a new instance
+     *
+     * @param modelAnalyser the model analyser
+     * @throws BackTracException BackTracException
+     * @throws PinException      PinException
+     */
+    public DependencyAnalyser(ModelAnalyser modelAnalyser) throws BackTracException, PinException {
+        sigMap = new HashMap<>();
+        for (Signal s : modelAnalyser.getInputs()) {
+            Set<ObservableValue> effected = new HashSet<>();
+            backTrac(s.getValue(), effected, MAX_LOOP_COUNTER);
+            sigMap.put(s, effected);
+        }
+    }
+
+    /**
+     * Returns all inputs the given output depends on
+     *
+     * @param output the output to analyse
+     * @return the list of inputs which effect the given output
+     */
+    public ArrayList<Signal> getInputs(Signal output) {
+        ArrayList<Signal> list = new ArrayList<>();
+        for (Map.Entry<Signal, Set<ObservableValue>> e : sigMap.entrySet()) {
+            if (e.getValue().contains(output.getValue())) {
+                list.add(e.getKey());
+            }
+        }
+        return list;
+    }
+
+    private void backTrac(ObservableValue value, Set<ObservableValue> effected, int depth) throws PinException, BackTracException {
+        effected.add(value);
+
+        if (depth < 0)
+            throw new BackTracException(Lang.get("err_backtracLoopFound"));
+
+        for (de.neemann.digital.core.Observer o : value) {
+            if ((o instanceof NodeInterface)) {
+                ObservableValues outputs = ((NodeInterface) o).getOutputs();
+                for (ObservableValue co : outputs)
+                    backTrac(co, effected, depth - 1);
+            } else
+                throw new BackTracException(Lang.get("err_backtracOf_N_isImpossible", o.getClass().getSimpleName()));
+        }
+    }
+
+}

src/main/java/de/neemann/digital/analyse/ModelAnalyser.java

@@ -84,7 +84,12 @@ public class ModelAnalyser {
             inputs.add(sig);
 
             ObservableValue notQ = ff.getOutputs().get(1);
-            q.addObserver(() -> notQ.setValue(~q.getValue()));
+            q.addObserver(new NodeWithoutDelay(notQ) {
+                @Override
+                public void hasChanged() {
+                    notQ.setValue(~q.getValue());
+                }
+            });
         }
 
         if (inputs.size() == 0)
@@ -167,10 +172,13 @@ public class ModelAnalyser {
                     final ObservableValue qout = ff.getOutputs().get(0);
                     final ObservableValue nqout = ff.getOutputs().get(1);
                     ObservableValue spq = outsp.getOutputs().get(0);
-                    spq.addObserver(() -> {
+                    spq.addObserver(new NodeWithoutDelay(qout, nqout) {
-                        final long value = spq.getValue();
+                        @Override
-                        qout.setValue(value);
+                        public void hasChanged() {
-                        nqout.setValue(~value);
+                            final long value = spq.getValue();
+                            qout.setValue(value);
+                            nqout.setValue(~value);
+                        }
                     });
 
                 } catch (NodeException e) {
@@ -216,7 +224,12 @@ public class ModelAnalyser {
                 try {
                     Splitter sp = Splitter.createNToOne(bits);
                     final ObservableValue out = sp.getOutputs().get(0);
-                    out.addObserver(() -> s.getValue().setValue(out.getValue()));
+                    out.addObserver(new NodeWithoutDelay(s.getValue()) {
+                        @Override
+                        public void hasChanged() {
+                            s.getValue().setValue(out.getValue());
+                        }
+                    });
                     out.fireHasChanged();
 
                     ObservableValues.Builder builder = new ObservableValues.Builder();
@@ -338,5 +351,17 @@ public class ModelAnalyser {
         }
     }
 
+    /**
+     * @return the models inputs
+     */
+    public ArrayList<Signal> getInputs() {
+        return inputs;
+    }
 
+    /**
+     * @return the models outputs
+     */
+    public ArrayList<Signal> getOutputs() {
+        return outputs;
+    }
 }

src/main/java/de/neemann/digital/core/BackTracException.java

@@ -0,0 +1,17 @@
+package de.neemann.digital.core;
+
+/**
+ * Indicates an error backtracking a value to all affected values
+ * Created by hneemann on 11.06.17.
+ */
+public class BackTracException extends Exception {
+
+    /**
+     * Creates a new instance
+     *
+     * @param message the message
+     */
+    public BackTracException(String message) {
+        super(message);
+    }
+}

src/main/java/de/neemann/digital/core/Model.java

@@ -41,7 +41,7 @@ public class Model implements Iterable<Node> {
     /**
      * Maximal number of calculation loops before oscillating behaviour is detected
      */
-    private static final int MAX_COUNTER = 1000;
+    public static final int MAX_LOOP_COUNTER = 1000;
 
     private final ArrayList<Clock> clocks;
     private final ArrayList<Break> breaks;
@@ -191,7 +191,7 @@ public class Model implements Iterable<Node> {
         int counter = 0;
         if (needsUpdate()) {
             while (needsUpdate()) {
-                if (counter++ > MAX_COUNTER) {
+                if (counter++ > MAX_LOOP_COUNTER) {
                     throw new NodeException(Lang.get("err_seemsToOscillate")).addNodes(nodesToUpdateNext);
                 }
                 doMicroStep(noise);

src/main/java/de/neemann/digital/core/Node.java

@@ -16,7 +16,7 @@ import java.io.File;
  *
  * @author hneemann
  */
-public abstract class Node implements Observer {
+public abstract class Node implements NodeInterface {
 
     private final boolean hasState;
     private Model model;

src/main/java/de/neemann/digital/core/NodeInterface.java

@@ -0,0 +1,19 @@
+package de.neemann.digital.core;
+
+import de.neemann.digital.draw.elements.PinException;
+
+/**
+ * The simplest possible node
+ * Created by hneemann on 11.06.17.
+ */
+public interface NodeInterface extends Observer {
+
+    /**
+     * returns the outputs effected by this node
+     *
+     * @return the outputs
+     * @throws PinException PinException
+     */
+    ObservableValues getOutputs() throws PinException;
+
+}

src/main/java/de/neemann/digital/core/NodeWithoutDelay.java

@@ -0,0 +1,35 @@
+package de.neemann.digital.core;
+
+import de.neemann.digital.draw.elements.PinException;
+
+/**
+ * A node which has no delay
+ * Created by hneemann on 11.06.17.
+ */
+public abstract class NodeWithoutDelay implements NodeInterface {
+
+    private ObservableValues outputs;
+
+    /**
+     * Creates a new instance
+     *
+     * @param outputs the nodes outputs
+     */
+    public NodeWithoutDelay(ObservableValue... outputs) {
+        this(new ObservableValues(outputs));
+    }
+
+    /**
+     * Creates a new instance
+     *
+     * @param outputs the nodes outputs
+     */
+    public NodeWithoutDelay(ObservableValues outputs) {
+        this.outputs = outputs;
+    }
+
+    @Override
+    public ObservableValues getOutputs() throws PinException {
+        return outputs;
+    }
+}

src/main/java/de/neemann/digital/core/Observable.java

@@ -8,7 +8,7 @@ import java.util.Iterator;
  *
  * @author hneemann
  */
-public class Observable {
+public class Observable implements Iterable<Observer> {
     private final ArrayList<Observer> observers;
 
     /**
@@ -75,4 +75,9 @@ public class Observable {
     public boolean hasObserver(Observer observer) {
         return observers.contains(observer);
     }
+
+    @Override
+    public Iterator<Observer> iterator() {
+        return observers.iterator();
+    }
 }

src/main/java/de/neemann/digital/core/ObservableValue.java

@@ -104,7 +104,7 @@ public class ObservableValue extends Observable implements PinDescription {
      * @return this for chained calls
      */
     public ObservableValue addObserverToValue(Observer observer) {
-        super.addObserver(observer);
+        addObserver(observer);
         return this;
     }
 

src/main/java/de/neemann/digital/core/element/Element.java

@@ -22,7 +22,7 @@ public interface Element {
     void setInputs(ObservableValues inputs) throws NodeException;
 
     /**
-     * When the connections between the elements are build all outputs a collected
+     * When the connections between the elements are build, all outputs are collected
      * by calling this method. After the interconnection they are set to the inputs
      * by calling <code>setInputs()</code>
      *

src/main/java/de/neemann/digital/core/pld/Diode.java

@@ -10,7 +10,7 @@ import de.neemann.digital.core.element.Keys;
  * A diode needed to create wired elements
  * Used to build a wired OR or AND.
  */
-public class Diode implements Element, Observer {
+public class Diode implements Element, NodeInterface {
 
     /**
      * The diodes description

src/main/java/de/neemann/digital/core/pld/DiodeForward.java

@@ -11,7 +11,7 @@ import static de.neemann.digital.core.element.PinInfo.input;
  * A diode needed to pull a wire to VDD.
  * Used to build a wired OR.
  */
-public class DiodeForward implements Element, Observer {
+public class DiodeForward implements Element, NodeInterface {
 
     /**
      * The diodes description

src/main/java/de/neemann/digital/core/switching/Switch.java

@@ -12,7 +12,7 @@ import de.neemann.digital.lang.Lang;
 /**
  * A simple switch
  */
-public class Switch implements Element, Observer {
+public class Switch implements Element, NodeInterface {
 
     /**
      * The switch description

src/main/java/de/neemann/digital/core/wiring/Splitter.java

@@ -141,14 +141,22 @@ public class Splitter implements Element {
                 final ObservableValue inValue = inputs.get(in.number);
                 final ObservableValue outValue = outputs.get(out.number);
                 if (highZIn)
-                    inValue.addObserverToValue(() -> {
+                    inValue.addObserverToValue(new NodeWithoutDelay(outValue) {
-                        if (inValue.isHighZ())
+                        @Override
-                            outValue.set(0, true);
+                        public void hasChanged() {
-                        else
+                            if (inValue.isHighZ())
-                            outValue.set(inValue.getValue() >> bitPos, false);
+                                outValue.set(0, true);
+                            else
+                                outValue.set(inValue.getValue() >> bitPos, false);
+                        }
                     });
                 else
-                    inValue.addObserverToValue(() -> outValue.setValue(inValue.getValue() >> bitPos));
+                    inValue.addObserverToValue(new NodeWithoutDelay(outValue) {
+                        @Override
+                        public void hasChanged() {
+                            outValue.setValue(inValue.getValue() >> bitPos);
+                        }
+                    });
                 break; // done!! out is completely filled!
             }
 
@@ -163,10 +171,13 @@ public class Splitter implements Element {
                 final long mask = ~(((1L << in.bits) - 1) << bitPos);
                 final ObservableValue inValue = inputs.get(in.number);
                 final ObservableValue outValue = outputs.get(out.number);
-                inputs.get(in.number).addObserverToValue(() -> {
+                inputs.get(in.number).addObserverToValue(new NodeWithoutDelay(outValue) {
-                    long in1 = inValue.getValue();
+                    @Override
-                    long out1 = outValue.getValue();
+                    public void hasChanged() {
-                    outValue.setValue((out1 & mask) | (in1 << bitPos));
+                        long in1 = inValue.getValue();
+                        long out1 = outValue.getValue();
+                        outValue.setValue((out1 & mask) | (in1 << bitPos));
+                    }
                 });
                 continue; // done with this input, its completely copied to the output!
             }
@@ -180,10 +191,13 @@ public class Splitter implements Element {
                 final int shift = out.getPos() - in.getPos();
                 final ObservableValue inValue = inputs.get(in.number);
                 final ObservableValue outValue = outputs.get(out.number);
-                inputs.get(in.number).addObserverToValue(() -> {
+                inputs.get(in.number).addObserverToValue(new NodeWithoutDelay(outValue) {
-                    long in12 = inValue.getValue();
+                    @Override
-                    long out12 = outValue.getValue();
+                    public void hasChanged() {
-                    outValue.setValue((out12 & mask) | (in12 >> shift));
+                        long in12 = inValue.getValue();
+                        long out12 = outValue.getValue();
+                        outValue.setValue((out12 & mask) | (in12 >> shift));
+                    }
                 });
                 continue;
             }
@@ -194,10 +208,13 @@ public class Splitter implements Element {
             final long mask = ~(((1L << bitsToCopy) - 1) << shift);
             final ObservableValue inValue = inputs.get(in.number);
             final ObservableValue outValue = outputs.get(out.number);
-            inputs.get(in.number).addObserverToValue(() -> {
+            inputs.get(in.number).addObserverToValue(new NodeWithoutDelay(outValue) {
-                long in13 = inValue.getValue();
+                @Override
-                long out13 = outValue.getValue();
+                public void hasChanged() {
-                outValue.setValue((out13 & mask) | (in13 << shift));
+                    long in13 = inValue.getValue();
+                    long out13 = outValue.getValue();
+                    outValue.setValue((out13 & mask) | (in13 << shift));
+                }
             });
 
         }

src/main/java/de/neemann/digital/draw/model/InverterConfig.java

@@ -1,5 +1,6 @@
 package de.neemann.digital.draw.model;
 
+import de.neemann.digital.core.NodeWithoutDelay;
 import de.neemann.digital.core.ObservableValue;
 
 import java.util.HashSet;
@@ -51,7 +52,12 @@ public class InverterConfig {
             return orig;
 
         ObservableValue out = new ObservableValue("~" + orig.getName(), orig.getBits());
-        orig.addObserver(() -> out.set(~orig.getValue(), orig.isHighZ()));
+        orig.addObserver(new NodeWithoutDelay(out) {
+            @Override
+            public void hasChanged() {
+                out.set(~orig.getValue(), orig.isHighZ());
+            }
+        });
         out.set(~orig.getValue(), orig.isHighZ());
         return out;
     }

src/main/java/de/neemann/digital/gui/components/table/ExpressionCreator.java

@@ -82,7 +82,7 @@ public class ExpressionCreator {
         TableReducer tr = new TableReducer(vars, boolTable);
         List<Variable> localVars = vars;
         if (tr.canReduce()) {
-            LOGGER.debug(resultName + " reduced from " + vars.size() + " to " + tr.getVars().size() + " variables");
+            LOGGER.debug(resultName + " reduced from " + vars.size() + " to " + tr.getVars().size() + " variables ("+tr.getVars()+")");
             boolTable = tr.getTable();
             localVars = tr.getVars();
         }

src/main/resources/lang/lang_de.xml

@@ -539,6 +539,8 @@ Sind evtl. die Namen der Variablen nicht eindeutig?</string>
     <string name="err_invalidTransmissionGateState">Die Steuereingänge eines Transmission-Gates müssen invertiert beschaltet werden!</string>
     <string name="err_nameUsedTwice_N">Signal {0} wurde mehrfach verwendet!</string>
     <string name="err_errorParsingTestdata">Fehler beim Einlesen der Testdaten.</string>
+    <string name="err_backtracLoopFound">Das Model enthält zirkuläre Abhängigkeiten.</string>
+    <string name="err_backtracOf_N_isImpossible">Die Modelkomponente {0} kann nicht analysiert werden.</string>
 
     <string name="key_AddrBits">Adress-Bits</string>
     <string name="key_AddrBits_tt">Anzahl der Adress-Bits die verwendet werden.</string>

src/main/resources/lang/lang_en.xml

@@ -529,6 +529,8 @@ The names of the variables may not be unique.</string>
     <string name="err_invalidTransmissionGateState">The two control inputs of a transmission gate must be inverted!</string>
     <string name="err_nameUsedTwice_N">Signal {0} is used twice!</string>
     <string name="err_errorParsingTestdata">Error parsing the test data.</string>
+    <string name="err_backtracLoopFound">Thes model contains circular dependencies.</string>
+    <string name="err_backtracOf_N_isImpossible">The model component {0} can not be analysed.</string>
 
     <string name="key_AddrBits">Address Bits</string>
     <string name="key_AddrBits_tt">Number of address bits used.</string>

src/test/java/de/neemann/digital/analyse/DependencyAnalyserTest.java

@@ -0,0 +1,62 @@
+package de.neemann.digital.analyse;
+
+import de.neemann.digital.core.*;
+import de.neemann.digital.draw.elements.PinException;
+import de.neemann.digital.integration.ToBreakRunner;
+import junit.framework.TestCase;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * @author hneemann
+ */
+public class DependencyAnalyserTest extends TestCase {
+
+    private static final int[] VAL = new int[]{1, 1, 1, 2, 6, 5, 5, 3, 8, 7, 7, 5, 10, 9, 9, 7, 2, 14, 14, 14, 14, 14, 14, 14, 2, 2};
+
+    public void testAnalyzer() throws Exception {
+        Model model = new ToBreakRunner("dig/backTrac/Plexer.dig").getModel();
+        ModelAnalyser m = new ModelAnalyser(model);
+        DependencyAnalyser da = new DependencyAnalyser(m);
+
+        assertEquals(17, m.getInputs().size());
+        assertEquals(26, m.getOutputs().size());
+        for (int i = 0; i < m.getOutputs().size(); i++)
+            assertEquals("" + i, VAL[i], da.getInputs(m.getOutputs().get(i)).size());
+    }
+
+}
+
+/*
+
+ExpressionCreator - p0n+1 reduced from 17 to 1 variables ([Count])
+ExpressionCreator - p1n+1 reduced from 17 to 1 variables ([p0n])
+ExpressionCreator - Q_1n+1 reduced from 17 to 1 variables ([Q_0n])
+ExpressionCreator - Q_0n+1 reduced from 17 to 2 variables ([Q_1n, Q_0n])
+ExpressionCreator - C0Q_3n+1 reduced from 17 to 6 variables ([p0n, p1n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n])
+ExpressionCreator - C0Q_2n+1 reduced from 17 to 5 variables ([p0n, p1n, C0Q_2n, C0Q_1n, C0Q_0n])
+ExpressionCreator - C0Q_1n+1 reduced from 17 to 5 variables ([p0n, p1n, C0Q_3n, C0Q_1n, C0Q_0n])
+ExpressionCreator - C0Q_0n+1 reduced from 17 to 3 variables ([p0n, p1n, C0Q_0n])
+ExpressionCreator - C1Q_3n+1 reduced from 17 to 8 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n])
+ExpressionCreator - C1Q_2n+1 reduced from 17 to 7 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_2n, C1Q_1n, C1Q_0n])
+ExpressionCreator - C1Q_1n+1 reduced from 17 to 7 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_1n, C1Q_0n])
+ExpressionCreator - C1Q_0n+1 reduced from 17 to 5 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_0n])
+ExpressionCreator - C2Q_3n+1 reduced from 17 to 10 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - C2Q_2n+1 reduced from 17 to 9 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_0n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - C2Q_1n+1 reduced from 17 to 9 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_0n, C2Q_3n, C2Q_1n, C2Q_0n])
+ExpressionCreator - C2Q_0n+1 reduced from 17 to 7 variables ([p0n, p1n, C0Q_3n, C0Q_0n, C1Q_3n, C1Q_0n, C2Q_0n])
+ExpressionCreator - s2 reduced from 17 to 2 variables ([Q_1n, Q_0n])
+ExpressionCreator - d0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - c0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - b0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - a0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - e0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - f0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - g0 reduced from 17 to 14 variables ([Q_1n, Q_0n, C0Q_3n, C0Q_2n, C0Q_1n, C0Q_0n, C1Q_3n, C1Q_2n, C1Q_1n, C1Q_0n, C2Q_3n, C2Q_2n, C2Q_1n, C2Q_0n])
+ExpressionCreator - s1 reduced from 17 to 2 variables ([Q_1n, Q_0n])
+ExpressionCreator - s0 reduced from 17 to 2 variables ([Q_1n, Q_0n])
+
+ */

src/test/resources/dig/backTrac/Plexer.dig

@@ -0,0 +1,569 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <attributes>
+    <entry>
+      <string>Width</string>
+      <int>5</int>
+    </entry>
+  </attributes>
+  <visualElements>
+    <visualElement>
+      <elementName>Clock</elementName>
+      <elementAttributes>
+        <entry>
+          <string>runRealTime</string>
+          <boolean>true</boolean>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>C</string>
+        </entry>
+        <entry>
+          <string>Frequency</string>
+          <int>20</int>
+        </entry>
+      </elementAttributes>
+      <pos x="240" y="100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Multiplexer</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Selector Bits</string>
+          <int>2</int>
+        </entry>
+        <entry>
+          <string>Bits</string>
+          <int>4</int>
+        </entry>
+      </elementAttributes>
+      <pos x="480" y="180"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Input Splitting</string>
+          <string>4</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>1*4</string>
+        </entry>
+      </elementAttributes>
+      <pos x="560" y="220"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Decoder</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Selector Bits</string>
+          <int>2</int>
+        </entry>
+        <entry>
+          <string>flipSelPos</string>
+          <boolean>true</boolean>
+        </entry>
+      </elementAttributes>
+      <pos x="480" y="420"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Input Splitting</string>
+          <string>1,1</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>2</string>
+        </entry>
+      </elementAttributes>
+      <pos x="400" y="460"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Ground</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Bits</string>
+          <int>4</int>
+        </entry>
+      </elementAttributes>
+      <pos x="460" y="260"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 18</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>s2</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>18</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="460"/>
+    </visualElement>
+    <visualElement>
+      <elementName>dif.dig</elementName>
+      <elementAttributes/>
+      <pos x="300" y="60"/>
+    </visualElement>
+    <visualElement>
+      <elementName>counter2Bit3.dig</elementName>
+      <elementAttributes/>
+      <pos x="300" y="460"/>
+    </visualElement>
+    <visualElement>
+      <elementName>decoder.dig</elementName>
+      <elementAttributes/>
+      <pos x="600" y="220"/>
+    </visualElement>
+    <visualElement>
+      <elementName>counter.dig</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>C0</string>
+        </entry>
+      </elementAttributes>
+      <pos x="300" y="180"/>
+    </visualElement>
+    <visualElement>
+      <elementName>counter.dig</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>C1</string>
+        </entry>
+      </elementAttributes>
+      <pos x="300" y="280"/>
+    </visualElement>
+    <visualElement>
+      <elementName>counter.dig</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>C2</string>
+        </entry>
+      </elementAttributes>
+      <pos x="300" y="380"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 14</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>d0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>8</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="220"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 12</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>c0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>6</int>
+        </entry>
+      </elementAttributes>
+      <pos x="860" y="240"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 11</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>b0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>5</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="260"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 9</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>a0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>4</int>
+        </entry>
+      </elementAttributes>
+      <pos x="860" y="280"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 8</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>e0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>9</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="300"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 6</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>f0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>11</int>
+        </entry>
+      </elementAttributes>
+      <pos x="860" y="320"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 5</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>g0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>12</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 17</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>s1</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>19</int>
+        </entry>
+      </elementAttributes>
+      <pos x="860" y="440"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 16</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>s0</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>20</int>
+        </entry>
+      </elementAttributes>
+      <pos x="700" y="420"/>
+    </visualElement>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Description</string>
+          <string>Pin 26</string>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>Count</string>
+        </entry>
+        <entry>
+          <string>pinNumber</string>
+          <int>26</int>
+        </entry>
+      </elementAttributes>
+      <pos x="240" y="60"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="380" y="480"/>
+      <p2 x="400" y="480"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="320"/>
+      <p2 x="860" y="320"/>
+    </wire>
+    <wire>
+      <p1 x="520" y="420"/>
+      <p2 x="700" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="580" y="260"/>
+      <p2 x="600" y="260"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="260"/>
+      <p2 x="700" y="260"/>
+    </wire>
+    <wire>
+      <p1 x="240" y="100"/>
+      <p2 x="260" y="100"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="100"/>
+      <p2 x="300" y="100"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="200"/>
+      <p2 x="400" y="200"/>
+    </wire>
+    <wire>
+      <p1 x="420" y="200"/>
+      <p2 x="480" y="200"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="200"/>
+      <p2 x="300" y="200"/>
+    </wire>
+    <wire>
+      <p1 x="520" y="460"/>
+      <p2 x="700" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="460"/>
+      <p2 x="300" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="420" y="460"/>
+      <p2 x="460" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="460"/>
+      <p2 x="400" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="140"/>
+      <p2 x="400" y="140"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="300"/>
+      <p2 x="400" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="300"/>
+      <p2 x="300" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="300"/>
+      <p2 x="700" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="400"/>
+      <p2 x="300" y="400"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="240"/>
+      <p2 x="400" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="580" y="240"/>
+      <p2 x="600" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="240"/>
+      <p2 x="480" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="240"/>
+      <p2 x="860" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="80"/>
+      <p2 x="400" y="80"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="340"/>
+      <p2 x="400" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="340"/>
+      <p2 x="500" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="340"/>
+      <p2 x="700" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="180"/>
+      <p2 x="300" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="180"/>
+      <p2 x="480" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="280"/>
+      <p2 x="300" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="280"/>
+      <p2 x="420" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="580" y="280"/>
+      <p2 x="600" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="280"/>
+      <p2 x="860" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="520" y="440"/>
+      <p2 x="860" y="440"/>
+    </wire>
+    <wire>
+      <p1 x="580" y="220"/>
+      <p2 x="600" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="520" y="220"/>
+      <p2 x="560" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="220"/>
+      <p2 x="480" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="220"/>
+      <p2 x="700" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="380"/>
+      <p2 x="300" y="380"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="380"/>
+      <p2 x="440" y="380"/>
+    </wire>
+    <wire>
+      <p1 x="240" y="60"/>
+      <p2 x="300" y="60"/>
+    </wire>
+    <wire>
+      <p1 x="400" y="200"/>
+      <p2 x="400" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="400" y="300"/>
+      <p2 x="400" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="400" y="80"/>
+      <p2 x="400" y="140"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="100"/>
+      <p2 x="260" y="200"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="400"/>
+      <p2 x="260" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="300"/>
+      <p2 x="260" y="400"/>
+    </wire>
+    <wire>
+      <p1 x="260" y="200"/>
+      <p2 x="260" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="420" y="200"/>
+      <p2 x="420" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="500" y="260"/>
+      <p2 x="500" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="500" y="340"/>
+      <p2 x="500" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="140"/>
+      <p2 x="280" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="240"/>
+      <p2 x="280" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="280" y="340"/>
+      <p2 x="280" y="380"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="220"/>
+      <p2 x="440" y="380"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="340"/>
+      <p2 x="460" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="240"/>
+      <p2 x="460" y="260"/>
+    </wire>
+  </wires>
+</circuit>

src/test/resources/dig/backTrac/counter2Bit3.dig

@@ -0,0 +1,277 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <attributes>
+    <entry>
+      <string>Width</string>
+      <int>4</int>
+    </entry>
+  </attributes>
+  <visualElements>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+        <entry>
+          <string>NetName</string>
+          <string>Q_1n</string>
+        </entry>
+      </elementAttributes>
+      <pos x="220" y="0"/>
+    </visualElement>
+    <visualElement>
+      <elementName>D_FF</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Q_1n</string>
+        </entry>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+      </elementAttributes>
+      <pos x="140" y="0"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+        <entry>
+          <string>NetName</string>
+          <string>Q_0n</string>
+        </entry>
+      </elementAttributes>
+      <pos x="220" y="100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>D_FF</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Q_0n</string>
+        </entry>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+      </elementAttributes>
+      <pos x="140" y="100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>And</elementName>
+      <elementAttributes/>
+      <pos x="20" y="80"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Q1</string>
+        </entry>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+      </elementAttributes>
+      <pos x="220" y="180"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Q0</string>
+        </entry>
+        <entry>
+          <string>Inputs</string>
+          <int>1</int>
+        </entry>
+      </elementAttributes>
+      <pos x="220" y="220"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="1"/>
+        </entry>
+        <entry>
+          <string>NetName</string>
+          <string>Q_0n</string>
+        </entry>
+      </elementAttributes>
+      <pos x="-80" y="-100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Not</elementName>
+      <elementAttributes>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="3"/>
+        </entry>
+      </elementAttributes>
+      <pos x="-60" y="-60"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="1"/>
+        </entry>
+        <entry>
+          <string>NetName</string>
+          <string>Q_1n</string>
+        </entry>
+      </elementAttributes>
+      <pos x="-40" y="-100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Not</elementName>
+      <elementAttributes>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="3"/>
+        </entry>
+      </elementAttributes>
+      <pos x="-20" y="-60"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Clock</elementName>
+      <elementAttributes>
+        <entry>
+          <string>runRealTime</string>
+          <boolean>true</boolean>
+        </entry>
+        <entry>
+          <string>rotation</string>
+          <rotation rotation="3"/>
+        </entry>
+        <entry>
+          <string>Label</string>
+          <string>C</string>
+        </entry>
+      </elementAttributes>
+      <pos x="120" y="-60"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="200" y="0"/>
+      <p2 x="220" y="0"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="0"/>
+      <p2 x="140" y="0"/>
+    </wire>
+    <wire>
+      <p1 x="-60" y="80"/>
+      <p2 x="20" y="80"/>
+    </wire>
+    <wire>
+      <p1 x="200" y="100"/>
+      <p2 x="220" y="100"/>
+    </wire>
+    <wire>
+      <p1 x="80" y="100"/>
+      <p2 x="140" y="100"/>
+    </wire>
+    <wire>
+      <p1 x="-40" y="180"/>
+      <p2 x="220" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="120" y="20"/>
+      <p2 x="140" y="20"/>
+    </wire>
+    <wire>
+      <p1 x="-20" y="120"/>
+      <p2 x="20" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="120" y="120"/>
+      <p2 x="140" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="220"/>
+      <p2 x="220" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="-80"/>
+      <p2 x="-60" y="-80"/>
+    </wire>
+    <wire>
+      <p1 x="-40" y="-80"/>
+      <p2 x="-20" y="-80"/>
+    </wire>
+    <wire>
+      <p1 x="-20" y="-80"/>
+      <p2 x="-20" y="-60"/>
+    </wire>
+    <wire>
+      <p1 x="-20" y="-20"/>
+      <p2 x="-20" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="-20" y="120"/>
+      <p2 x="-20" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="-40" y="-100"/>
+      <p2 x="-40" y="-80"/>
+    </wire>
+    <wire>
+      <p1 x="-40" y="180"/>
+      <p2 x="-40" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="-40" y="-80"/>
+      <p2 x="-40" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="120" y="-60"/>
+      <p2 x="120" y="20"/>
+    </wire>
+    <wire>
+      <p1 x="120" y="20"/>
+      <p2 x="120" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="-60" y="-80"/>
+      <p2 x="-60" y="-60"/>
+    </wire>
+    <wire>
+      <p1 x="-60" y="-20"/>
+      <p2 x="-60" y="80"/>
+    </wire>
+    <wire>
+      <p1 x="-60" y="80"/>
+      <p2 x="-60" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="-100"/>
+      <p2 x="-80" y="-80"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="0"/>
+      <p2 x="-80" y="220"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="220"/>
+      <p2 x="-80" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="-80" y="-80"/>
+      <p2 x="-80" y="0"/>
+    </wire>
+  </wires>
+</circuit>

src/test/resources/dig/backTrac/dif.dig

@@ -0,0 +1,129 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <attributes>
+    <entry>
+      <string>Width</string>
+      <int>4</int>
+    </entry>
+  </attributes>
+  <visualElements>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Count</string>
+        </entry>
+      </elementAttributes>
+      <pos x="320" y="180"/>
+    </visualElement>
+    <visualElement>
+      <elementName>D_FF</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>p0</string>
+        </entry>
+      </elementAttributes>
+      <pos x="380" y="180"/>
+    </visualElement>
+    <visualElement>
+      <elementName>D_FF</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>p1</string>
+        </entry>
+      </elementAttributes>
+      <pos x="380" y="280"/>
+    </visualElement>
+    <visualElement>
+      <elementName>And</elementName>
+      <elementAttributes/>
+      <pos x="480" y="260"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Clock</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>C</string>
+        </entry>
+      </elementAttributes>
+      <pos x="320" y="240"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Out</string>
+        </entry>
+      </elementAttributes>
+      <pos x="560" y="280"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="360" y="240"/>
+      <p2 x="460" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="320" y="240"/>
+      <p2 x="340" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="320" y="180"/>
+      <p2 x="380" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="180"/>
+      <p2 x="460" y="180"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="260"/>
+      <p2 x="480" y="260"/>
+    </wire>
+    <wire>
+      <p1 x="340" y="200"/>
+      <p2 x="380" y="200"/>
+    </wire>
+    <wire>
+      <p1 x="360" y="280"/>
+      <p2 x="380" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="540" y="280"/>
+      <p2 x="560" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="340" y="300"/>
+      <p2 x="380" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="300"/>
+      <p2 x="480" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="340" y="200"/>
+      <p2 x="340" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="340" y="240"/>
+      <p2 x="340" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="360" y="240"/>
+      <p2 x="360" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="180"/>
+      <p2 x="460" y="240"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="240"/>
+      <p2 x="460" y="260"/>
+    </wire>
+  </wires>
+</circuit>