diff -r 925d2de2a277 -r d382dacfd73f rt/vm/src/main/java/org/apidesign/vm4brwsr/VarType.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rt/vm/src/main/java/org/apidesign/vm4brwsr/VarType.java	Tue Feb 26 16:54:16 2013 +0100
@@ -0,0 +1,110 @@
+/**
+ * Back 2 Browser Bytecode Translator
+ * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. Look for COPYING file in the top folder.
+ * If not, see http://opensource.org/licenses/GPL-2.0.
+ */
+package org.apidesign.vm4brwsr;
+
+import org.apidesign.javap.RuntimeConstants;
+
+final class VarType {
+    public static final int INTEGER = 0;
+    public static final int LONG = 1;
+    public static final int FLOAT = 2;
+    public static final int DOUBLE = 3;
+    public static final int REFERENCE = 4;
+
+    public static final int LAST = REFERENCE;
+
+    private VarType() {
+    }
+
+    public static boolean isCategory2(final int varType) {
+        return (varType == LONG) || (varType == DOUBLE);
+    }
+
+    public static int fromStackMapType(final int smType) {
+        switch (smType & 0xff) {
+            case RuntimeConstants.ITEM_Integer:
+                return VarType.INTEGER;
+            case RuntimeConstants.ITEM_Float:
+                return VarType.FLOAT;
+            case RuntimeConstants.ITEM_Double:
+                return VarType.DOUBLE;
+            case RuntimeConstants.ITEM_Long:
+                return VarType.LONG;
+            case RuntimeConstants.ITEM_Null:
+            case RuntimeConstants.ITEM_InitObject:
+            case RuntimeConstants.ITEM_Object:
+            case RuntimeConstants.ITEM_NewObject:
+                return VarType.REFERENCE;
+
+            case RuntimeConstants.ITEM_Bogus:
+                /* unclear how to handle for now */
+            default:
+                throw new IllegalStateException("Unhandled stack map type");
+        }
+    }
+
+    public static int fromConstantType(final byte constantTag) {
+        switch (constantTag) {
+            case RuntimeConstants.CONSTANT_INTEGER:
+                return VarType.INTEGER;
+            case RuntimeConstants.CONSTANT_FLOAT:
+                return VarType.FLOAT;
+            case RuntimeConstants.CONSTANT_LONG:
+                return VarType.LONG;
+            case RuntimeConstants.CONSTANT_DOUBLE:
+                return VarType.DOUBLE;
+
+            case RuntimeConstants.CONSTANT_CLASS:
+            case RuntimeConstants.CONSTANT_UTF8:
+            case RuntimeConstants.CONSTANT_UNICODE:
+            case RuntimeConstants.CONSTANT_STRING:
+                return VarType.REFERENCE;
+
+            case RuntimeConstants.CONSTANT_FIELD:
+            case RuntimeConstants.CONSTANT_METHOD:
+            case RuntimeConstants.CONSTANT_INTERFACEMETHOD:
+            case RuntimeConstants.CONSTANT_NAMEANDTYPE:
+                /* unclear how to handle for now */
+            default:
+                throw new IllegalStateException("Unhandled constant tag");
+        }
+    }
+
+    public static int fromFieldType(final char fieldType) {
+        switch (fieldType) {
+            case 'B':
+            case 'C':
+            case 'S':
+            case 'Z':
+            case 'I':
+                return VarType.INTEGER;
+            case 'J':
+                return VarType.LONG;
+            case 'F':
+                return VarType.FLOAT;
+            case 'D':
+                return VarType.DOUBLE;
+            case 'L':
+            case '[':
+                return VarType.REFERENCE;
+
+            default:
+                throw new IllegalStateException("Unhandled field type");
+        }
+    }
+}