added bus and multiplexer

src/main/java/de/neemann/digital/BurnException.java

@@ -0,0 +1,23 @@
+package de.neemann.digital;
+
+/**
+ * @author hneemann
+ */
+public class BurnException extends NodeException {
+    private final ObservableValue v1;
+    private final ObservableValue v2;
+
+    public BurnException(ObservableValue v1, ObservableValue v2) {
+        super("burnException");
+        this.v1 = v1;
+        this.v2 = v2;
+    }
+
+    public ObservableValue getV1() {
+        return v1;
+    }
+
+    public ObservableValue getV2() {
+        return v2;
+    }
+}

src/main/java/de/neemann/digital/HighZException.java

@@ -0,0 +1,17 @@
+package de.neemann.digital;
+
+/**
+ * @author hneemann
+ */
+public class HighZException extends NodeException {
+    private final ObservableValue causedObservable;
+
+    public HighZException(ObservableValue causedObservable) {
+        super("readOfHighZ");
+        this.causedObservable = causedObservable;
+    }
+
+    public ObservableValue getCausedObservable() {
+        return causedObservable;
+    }
+}

src/main/java/de/neemann/digital/Listener.java

@@ -4,5 +4,5 @@ package de.neemann.digital;
  * @author hneemann
  */
 public interface Listener {
-    void needsUpdate() throws NodeException;
+    void needsUpdate();
 }

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

@@ -13,9 +13,9 @@ public abstract class Node implements Listener {
     }
 
     @Override
-    public void needsUpdate() throws NodeException {
+    public void needsUpdate() {
         if (model == null)
-            throw new NodeException("no model set");
+            throw new RuntimeException("noModelSet");
 
         if (model.getVersion() != version) {
             model.addToUpdateList(this);
@@ -25,7 +25,7 @@ public abstract class Node implements Listener {
 
     /**
      * Only read the input!
-     * It is not allowed to write to the outputs!!!
+     * It is not allowed to write to one of the outputs!!!
      *
      * @throws NodeException
      */
@@ -33,10 +33,12 @@ public abstract class Node implements Listener {
 
     /**
      * Only write to the output!
-     * It is not allowed to read from the inputs!!!
+     * It is not allowed to read from one of the inputs!!!
      *
      * @throws NodeException
      */
     public abstract void writeOutputs() throws NodeException;
 
+    public void checkConsistence() throws NodeException {
+    }
 }

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

@@ -5,18 +5,20 @@ import java.util.ArrayList;
 /**
  * @author hneemann
  */
-public class ObservableValue {
+public class ObservableValue extends Value {
 
-    private final int bits;
-    private int value;
-    private ArrayList<Listener> listeners;
+    private final ArrayList<Listener> listeners;
 
     public ObservableValue(int bits) {
-        this.bits = bits;
+        this(bits, false);
+    }
+
+    public ObservableValue(int bits, boolean highZ) {
+        super(bits, highZ);
         listeners = new ArrayList<>();
     }
 
-    public void addListener(Listener listener) throws NodeException {
+    public void addListener(Listener listener) {
         listeners.add(listener);
     }
 
@@ -24,29 +26,32 @@ public class ObservableValue {
         listeners.remove(listener);
     }
 
-    public void hasChanged() throws NodeException {
+    public void hasChanged() {
         for (Listener l : listeners) {
             l.needsUpdate();
         }
     }
 
-    public int getValue() {
-        return value;
-    }
-
-    public void setValue(int value) throws NodeException {
-        if (this.value != value) {
-            this.value = value;
-            hasChanged();
-        }
-    }
-
     public int getBits() {
         return bits;
     }
 
-    public int getValueBits() {
-        return getValueBits(value);
+    public int getValue() throws NodeException {
+        if (highZ)
+            throw new HighZException(this);
+        return value;
+    }
+
+    public void setValue(int value) {
+        if (this.value != value) {
+            this.value = value;
+            if (!highZ)
+                hasChanged();
+        }
+    }
+
+    public int getValueBits() throws NodeException {
+        return getValueBits(getValue());
     }
 
     public int getValueBits(int value) {
@@ -59,10 +64,28 @@ public class ObservableValue {
         }
     }
 
+    public boolean isHighZ() {
+        return highZ;
+    }
+
+    public void setHighZ(boolean highZ) {
+        if (this.highZ != highZ) {
+            this.highZ = highZ;
+            hasChanged();
+        }
+    }
+
+
+    @Override
+    public void set(int value, boolean highZ) {
+        setValue(value);
+        setHighZ(highZ);
+    }
+
     @Override
     public String toString() {
         return "ObservableValue{" +
-                "value=" + value +
+                "value=" + (highZ ? "??" : value) +
                 ", bits=" + bits +
                 '}';
     }

src/main/java/de/neemann/digital/Value.java

@@ -0,0 +1,28 @@
+package de.neemann.digital;
+
+/**
+ * @author hneemann
+ */
+public class Value {
+    protected final int bits;
+    protected boolean highZ;
+    protected int value;
+
+    public Value(int bits) {
+        this(bits, false);
+    }
+
+    public Value(int bits, boolean highZ) {
+        this.bits = bits;
+        this.highZ = highZ;
+    }
+
+    public void set(int value, boolean highZ) {
+        this.value = value;
+        this.highZ = highZ;
+    }
+
+    public void set(Value v) {
+        set(v.value, v.highZ);
+    }
+}

src/main/java/de/neemann/digital/basic/And.java

@@ -1,5 +1,6 @@
 package de.neemann.digital.basic;
 
+import de.neemann.digital.NodeException;
 import de.neemann.digital.ObservableValue;
 
 import java.util.ArrayList;
@@ -14,7 +15,7 @@ public class And extends Function {
     }
 
     @Override
-    protected int calculate(ArrayList<ObservableValue> inputs) {
+    protected int calculate(ArrayList<ObservableValue> inputs) throws NodeException {
         int f = -1;
         for (ObservableValue i : inputs) {
             f &= i.getValue();

src/main/java/de/neemann/digital/basic/FanIn.java

@@ -0,0 +1,37 @@
+package de.neemann.digital.basic;
+
+import de.neemann.digital.BitsException;
+import de.neemann.digital.Node;
+import de.neemann.digital.NodeException;
+import de.neemann.digital.ObservableValue;
+
+import java.util.ArrayList;
+
+/**
+ * @author hneemann
+ */
+public abstract class FanIn extends Node {
+    protected final ArrayList<ObservableValue> inputs;
+    protected final ObservableValue output;
+
+    public FanIn(int bits) {
+        inputs = new ArrayList<>();
+        output = new ObservableValue(bits);
+    }
+
+    public FanIn addInput(ObservableValue value) throws BitsException, NodeException {
+        output.checkBits(value);
+        inputs.add(value);
+        value.addListener(this);
+        return this;
+    }
+
+    public void removeInput(ObservableValue value) {
+        inputs.remove(value);
+        value.removeListener(this);
+    }
+
+    public ObservableValue getOutput() {
+        return output;
+    }
+}

src/main/java/de/neemann/digital/basic/Function.java

@@ -1,7 +1,5 @@
 package de.neemann.digital.basic;
 
-import de.neemann.digital.BitsException;
-import de.neemann.digital.Node;
 import de.neemann.digital.NodeException;
 import de.neemann.digital.ObservableValue;
 
@@ -10,34 +8,14 @@ import java.util.ArrayList;
 /**
  * @author hneemann
  */
-public abstract class Function extends Node {
+public abstract class Function extends FanIn {
 
-    private final ArrayList<ObservableValue> inputs;
-    private final ObservableValue output;
     private int value;
 
     public Function(int bits) {
-        output = new ObservableValue(bits);
-        inputs = new ArrayList<>();
+        super(bits);
     }
 
-    public Function addInput(ObservableValue value) throws BitsException, NodeException {
-        output.checkBits(value);
-        inputs.add(value);
-        value.addListener(this);
-        return this;
-    }
-
-    public void removeInput(ObservableValue value) {
-        inputs.remove(value);
-        value.removeListener(this);
-    }
-
-    public ObservableValue getOutput() {
-        return output;
-    }
-
-
     @Override
     public void readInputs() throws NodeException {
         value = calculate(inputs);
@@ -48,5 +26,5 @@ public abstract class Function extends Node {
         output.setValue(value);
     }
 
-    protected abstract int calculate(ArrayList<ObservableValue> inputs);
+    protected abstract int calculate(ArrayList<ObservableValue> inputs) throws NodeException;
 }

src/main/java/de/neemann/digital/basic/NAnd.java

@@ -1,5 +1,6 @@
 package de.neemann.digital.basic;
 
+import de.neemann.digital.NodeException;
 import de.neemann.digital.ObservableValue;
 
 import java.util.ArrayList;
@@ -14,7 +15,7 @@ public class NAnd extends Function {
     }
 
     @Override
-    protected int calculate(ArrayList<ObservableValue> inputs) {
+    protected int calculate(ArrayList<ObservableValue> inputs) throws NodeException {
         int f = -1;
         for (ObservableValue i : inputs) {
             f &= i.getValue();

src/main/java/de/neemann/digital/basic/NOr.java

@@ -1,5 +1,6 @@
 package de.neemann.digital.basic;
 
+import de.neemann.digital.NodeException;
 import de.neemann.digital.ObservableValue;
 
 import java.util.ArrayList;
@@ -13,7 +14,7 @@ public class NOr extends Function {
     }
 
     @Override
-    protected int calculate(ArrayList<ObservableValue> inputs) {
+    protected int calculate(ArrayList<ObservableValue> inputs) throws NodeException {
         int f = 0;
         for (ObservableValue i : inputs) {
             f |= i.getValue();

src/main/java/de/neemann/digital/basic/Or.java

@@ -1,5 +1,6 @@
 package de.neemann.digital.basic;
 
+import de.neemann.digital.NodeException;
 import de.neemann.digital.ObservableValue;
 
 import java.util.ArrayList;
@@ -14,7 +15,7 @@ public class Or extends Function {
     }
 
     @Override
-    protected int calculate(ArrayList<ObservableValue> inputs) {
+    protected int calculate(ArrayList<ObservableValue> inputs) throws NodeException {
         int f = 0;
         for (ObservableValue i : inputs) {
             f |= i.getValue();

src/main/java/de/neemann/digital/wiring/Bus.java

@@ -0,0 +1,42 @@
+package de.neemann.digital.wiring;
+
+import de.neemann.digital.BurnException;
+import de.neemann.digital.NodeException;
+import de.neemann.digital.ObservableValue;
+import de.neemann.digital.Value;
+import de.neemann.digital.basic.FanIn;
+
+/**
+ * @author hneemann
+ */
+public class Bus extends FanIn {
+
+    private Value value;
+
+    public Bus(int bits) {
+        super(bits);
+        value = new Value(bits);
+    }
+
+    @Override
+    public void readInputs() throws NodeException {
+        ObservableValue found = null;
+        for (ObservableValue in : inputs) {
+            if (!in.isHighZ()) {
+                if (found != null)
+                    throw new BurnException(in, found);
+                found = in;
+            }
+        }
+        if (found == null) {
+            value.set(0, true);
+        } else {
+            value.set(found.getValue(), false);
+        }
+    }
+
+    @Override
+    public void writeOutputs() throws NodeException {
+        output.set(value);
+    }
+}

src/main/java/de/neemann/digital/wiring/Multiplexer.java

@@ -0,0 +1,34 @@
+package de.neemann.digital.wiring;
+
+import de.neemann.digital.NodeException;
+import de.neemann.digital.ObservableValue;
+import de.neemann.digital.basic.FanIn;
+
+/**
+ * @author hneemann
+ */
+public class Multiplexer extends FanIn {
+
+    private ObservableValue selector;
+    private int value;
+
+    public Multiplexer(int bits, ObservableValue selector) {
+        super(bits);
+        this.selector = selector;
+        selector.addListener(this);
+    }
+
+    @Override
+    public void readInputs() throws NodeException {
+        int n = selector.getValueBits();
+        if (n >= inputs.size())
+            throw new NodeException("multiplexerSelectsNotPresentInput");
+
+        value = inputs.get(n).getValue();
+    }
+
+    @Override
+    public void writeOutputs() throws NodeException {
+        output.setValue(value);
+    }
+}

src/test/java/de/neemann/digital/FlipFlops.java

@@ -13,8 +13,8 @@ public class FlipFlops extends TestCase {
         ObservableValue s = new ObservableValue(1);
 
         Model model = new Model();
-        Function a1 = model.add(new NOr(1)).addInput(r);
-        Function a2 = model.add(new NOr(1)).addInput(s);
+        FanIn a1 = model.add(new NOr(1)).addInput(r);
+        FanIn a2 = model.add(new NOr(1)).addInput(s);
 
         a1.addInput(a2.getOutput());
         a2.addInput(a1.getOutput());
@@ -39,8 +39,8 @@ public class FlipFlops extends TestCase {
         ObservableValue s = new ObservableValue(1);
 
         Model model = new Model();
-        Function a1 = model.add(new NAnd(1)).addInput(r);
-        Function a2 = model.add(new NAnd(1)).addInput(s);
+        FanIn a1 = model.add(new NAnd(1)).addInput(r);
+        FanIn a2 = model.add(new NAnd(1)).addInput(s);
 
         a1.addInput(a2.getOutput());
         a2.addInput(a1.getOutput());
@@ -60,22 +60,22 @@ public class FlipFlops extends TestCase {
         ObservableValue c = new ObservableValue(1);
 
         Model model = new Model();
-        Function a1 = model.add(new And(1)).addInput(j).addInput(c);
-        Function a2 = model.add(new And(1)).addInput(k).addInput(c);
+        FanIn a1 = model.add(new And(1)).addInput(j).addInput(c);
+        FanIn a2 = model.add(new And(1)).addInput(k).addInput(c);
         Not not = model.add(new Not(c));
 
-        Function nor1 = model.add(new NOr(1)).addInput(a1.getOutput());
-        Function nor2 = model.add(new NOr(1)).addInput(a2.getOutput());
+        FanIn nor1 = model.add(new NOr(1)).addInput(a1.getOutput());
+        FanIn nor2 = model.add(new NOr(1)).addInput(a2.getOutput());
 
         nor1.addInput(nor2.getOutput());
         nor2.addInput(nor1.getOutput());
 
 
-        Function a3 = model.add(new And(1)).addInput(nor1.getOutput()).addInput(not.getOutput());
-        Function a4 = model.add(new And(1)).addInput(nor2.getOutput()).addInput(not.getOutput());
+        FanIn a3 = model.add(new And(1)).addInput(nor1.getOutput()).addInput(not.getOutput());
+        FanIn a4 = model.add(new And(1)).addInput(nor2.getOutput()).addInput(not.getOutput());
 
-        Function nor3 = model.add(new NOr(1)).addInput(a3.getOutput());
-        Function nor4 = model.add(new NOr(1)).addInput(a4.getOutput());
+        FanIn nor3 = model.add(new NOr(1)).addInput(a3.getOutput());
+        FanIn nor4 = model.add(new NOr(1)).addInput(a4.getOutput());
 
         nor3.addInput(nor4.getOutput());
         nor4.addInput(nor3.getOutput());

src/test/java/de/neemann/digital/TestExecuter.java

@@ -39,7 +39,7 @@ public class TestExecuter {
         for (int i = 0; i < outputs.length; i++) {
             int should = val[i + inputs.length];
             if (should >= 0)
-                assertEquals("Value " + i, outputs[i].getValueBits(should), outputs[i].getValueBits());
+                assertEquals("output " + i, outputs[i].getValueBits(should), outputs[i].getValueBits());
         }
     }
 

src/test/java/de/neemann/digital/basic/AndTest.java

@@ -16,9 +16,9 @@ public class AndTest extends TestCase {
 
 
         Model model = new Model();
-        Function and = model.add(new And(1)).addInput(a).addInput(b);
+        ObservableValue out = model.add(new And(1)).addInput(a).addInput(b).getOutput();
 
-        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(and.getOutput());
+        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(out);
         sc.check(0, 0, 0);
         sc.check(1, 0, 0);
         sc.check(0, 1, 0);

src/test/java/de/neemann/digital/basic/NAndTest.java

@@ -15,9 +15,9 @@ public class NAndTest extends TestCase {
         ObservableValue b = new ObservableValue(1);
 
         Model model = new Model();
-        Function nand = model.add(new NAnd(1)).addInput(a).addInput(b);
+        ObservableValue out = model.add(new NAnd(1)).addInput(a).addInput(b).getOutput();
 
-        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(nand.getOutput());
+        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(out);
         sc.check(0, 0, 1);
         sc.check(1, 0, 1);
         sc.check(0, 1, 1);

src/test/java/de/neemann/digital/basic/NOrTest.java

@@ -15,9 +15,9 @@ public class NOrTest extends TestCase {
         ObservableValue b = new ObservableValue(1);
 
         Model model = new Model();
-        Function nor = model.add(new NOr(1)).addInput(a).addInput(b);
+        ObservableValue nor = model.add(new NOr(1)).addInput(a).addInput(b).getOutput();
 
-        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(nor.getOutput());
+        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(nor);
         sc.check(0, 0, 1);
         sc.check(1, 0, 0);
         sc.check(0, 1, 0);

src/test/java/de/neemann/digital/basic/OrTest.java

@@ -15,9 +15,9 @@ public class OrTest extends TestCase {
         ObservableValue b = new ObservableValue(1);
 
         Model model = new Model();
-        Function and = model.add(new Or(1)).addInput(a).addInput(b);
+        ObservableValue and = model.add(new Or(1)).addInput(a).addInput(b).getOutput();
 
-        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(and.getOutput());
+        TestExecuter sc = new TestExecuter(model).setInputs(a, b).setOutputs(and);
         sc.check(0, 0, 0);
         sc.check(1, 0, 1);
         sc.check(0, 1, 1);

src/test/java/de/neemann/digital/wiring/BusTest.java

@@ -0,0 +1,46 @@
+package de.neemann.digital.wiring;
+
+import de.neemann.digital.BurnException;
+import de.neemann.digital.Model;
+import de.neemann.digital.ObservableValue;
+import de.neemann.digital.TestExecuter;
+import junit.framework.TestCase;
+
+/**
+ * @author hneemann
+ */
+public class BusTest extends TestCase {
+
+    public void testBus() throws Exception {
+        Model model = new Model();
+        ObservableValue a = new ObservableValue(1, true);
+        ObservableValue b = new ObservableValue(1);
+        ObservableValue out = model.add(new Bus(1)).addInput(a).addInput(b).getOutput();
+
+        TestExecuter te = new TestExecuter(model).setInputs(a, b).setOutputs(out);
+        te.check(0, 0, 0);
+        te.check(0, 1, 1);
+        a.setHighZ(false);
+        b.setHighZ(true);
+        te.check(0, 1, 0);
+        te.check(1, 0, 1);
+        a.setHighZ(false);
+        b.setHighZ(false);
+        try {
+            te.check(0, 0, 0);
+            assertTrue(false);
+        } catch (BurnException e) {
+            assertTrue(true);
+        }
+    }
+
+    public void testBusHighZ() throws Exception {
+        Model model = new Model();
+        ObservableValue a = new ObservableValue(1, true);
+        ObservableValue b = new ObservableValue(1, true);
+        ObservableValue out = model.add(new Bus(1)).addInput(a).addInput(b).getOutput();
+
+        TestExecuter te = new TestExecuter(model).setInputs(a, b).setOutputs(out);
+        assertTrue(out.isHighZ());
+    }
+}

src/test/java/de/neemann/digital/wiring/MultiplexerTest.java

@@ -0,0 +1,30 @@
+package de.neemann.digital.wiring;
+
+import de.neemann.digital.Model;
+import de.neemann.digital.ObservableValue;
+import de.neemann.digital.TestExecuter;
+import junit.framework.TestCase;
+
+/**
+ * @author hneemann
+ */
+public class MultiplexerTest extends TestCase {
+
+    public void testMux() throws Exception {
+        Model model = new Model();
+        ObservableValue a = new ObservableValue(4);
+        ObservableValue b = new ObservableValue(4);
+        ObservableValue c = new ObservableValue(4);
+        ObservableValue d = new ObservableValue(4);
+        ObservableValue sel = new ObservableValue(2);
+        ObservableValue out = model.add(new Multiplexer(4, sel)).addInput(a).addInput(b).addInput(c).addInput(d).getOutput();
+
+
+        TestExecuter te = new TestExecuter(model).setInputs(a, b, c, d, sel).setOutputs(out);
+        te.check(3, 4, 5, 6, 0, 3);
+        te.check(3, 4, 5, 6, 1, 4);
+        te.check(3, 4, 5, 6, 2, 5);
+        te.check(3, 4, 5, 6, 3, 6);
+
+    }
+}