Fixed some bug concerning switches

added a 16-Bit SRAM example

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

@@ -9,9 +9,10 @@ public interface PinDescription {
 
     /**
      * The possible pull resistor configurations
+     * "both" is an error condition which can happen if nets are merged
      */
     enum PullResistor {
-        none, pullUp, pullDown
+        none, pullUp, pullDown, both
     }
 
     /**

src/main/java/de/neemann/digital/core/wiring/bus/AbstractBusHandler.java

@@ -54,6 +54,10 @@ public abstract class AbstractBusHandler {
     public void recalculate() {
         long value = 0;
         burn = false;
+        if (getResistor().equals(PinDescription.PullResistor.both)) {
+            burn = true;
+            set(0, true);
+        } else {
             boolean highz = true;
             for (ObservableValue input : getInputs()) {
                 if (!input.isHighZ()) {
@@ -75,10 +79,11 @@ public abstract class AbstractBusHandler {
                         set(0, false);
                         break;
                     default:
-                    set(value, highz);
+                        set(value, true);
                 }
             } else
-            set(value, highz);
+                set(value, false);
+        }
 
         // if burn condition and not yet added for post step check add for post step check
         if (burn && (obs.getVersion() != addedVersion)) {
@@ -89,7 +94,7 @@ public abstract class AbstractBusHandler {
 
     /**
      * Called to check if this net is in a burn condition.
-     * A burn condition does not immediately throw an exception, because intermediate burn condition are
+     * A burn condition does not immediately throw an exception, because intermediate burn conditions are
      * unavoidable. So this method is called if the step is completed. If a step ends with a burn condition
      * an exception is thrown.
      */

src/main/java/de/neemann/digital/core/wiring/bus/BusModelStateObserver.java

@@ -97,6 +97,7 @@ public final class BusModelStateObserver implements ModelStateObserver {
                         h1.addNet(h2);
                         for (CommonBusValue v : h2.getValues())
                             netMap.put(v, h1);
+                        createdHandlers.remove(h2);
                     }
                 }
             }

src/main/java/de/neemann/digital/core/wiring/bus/ConnectedBusHandler.java

@@ -1,6 +1,5 @@
 package de.neemann.digital.core.wiring.bus;
 
-import de.neemann.digital.core.BurnException;
 import de.neemann.digital.core.ObservableValue;
 import de.neemann.digital.core.element.PinDescription;
 
@@ -43,8 +42,8 @@ public final class ConnectedBusHandler extends AbstractBusHandler {
                 resistor = net.getResistor();
             } else {
                 if (!resistor.equals(net.getResistor())) {
-                    // ToDo different resistors!
+                    // set error condition
-                    throw new BurnException(inputs);
+                    resistor = PinDescription.PullResistor.both;
                 }
             }
         }

src/test/java/de/neemann/digital/core/wiring/bus/ConnectedBusHandlerTest.java

@@ -0,0 +1,30 @@
+package de.neemann.digital.core.wiring.bus;
+
+import de.neemann.digital.core.ObservableValue;
+import de.neemann.digital.core.element.PinDescription;
+import junit.framework.TestCase;
+
+/**
+ * Created by hneemann on 05.03.17.
+ */
+public class ConnectedBusHandlerTest extends TestCase {
+
+    public void testNets() {
+        BusModelStateObserver obs = new BusModelStateObserver();
+        ConnectedBusHandler cbh = new ConnectedBusHandler(obs);
+
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.none, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.none, cbh.getResistor());
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.pullUp, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.pullUp, cbh.getResistor());
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.pullDown, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.both, cbh.getResistor());
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.pullDown, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.both, cbh.getResistor());
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.pullUp, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.both, cbh.getResistor());
+        cbh.addNet(new CommonBusValue(1, obs, PinDescription.PullResistor.none, new ObservableValue[]{}));
+        assertEquals(PinDescription.PullResistor.both, cbh.getResistor());
+    }
+
+}

src/test/java/de/neemann/digital/integration/TestExamples.java

@@ -28,7 +28,7 @@ public class TestExamples extends TestCase {
      */
     public void testDistExamples() throws Exception {
         File examples = new File(Resources.getRoot().getParentFile().getParentFile(), "/main/dig");
-        assertEquals(99, new FileScanner(this::check).scan(examples));
+        assertEquals(100, new FileScanner(this::check).scan(examples));
         assertEquals(51, testCasesInFiles);
     }