diff -r 4c2b92281cdc -r e606853325f1 vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java
--- a/vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java	Thu Jan 31 20:19:38 2013 +0100
+++ b/vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java	Thu Jan 31 20:37:12 2013 +0100
@@ -127,4 +127,12 @@
         DataInputStream disY = new DataInputStream(isY);
         return (disX.readLong() | disY.readLong());
     }
+    
+    public static long xorL(byte[] arrX, byte[] arrY) throws IOException {
+        ByteArrayInputStream isX = new ByteArrayInputStream(arrX);
+        DataInputStream disX = new DataInputStream(isX);
+        ByteArrayInputStream isY = new ByteArrayInputStream(arrY);
+        DataInputStream disY = new DataInputStream(isY);
+        return (disX.readLong() ^ disY.readLong());
+    }
 }