1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.bcel.internal.generic;
  23 
  24 import java.io.*;
  25 
  26 /**
  27  * GOTO - Branch always (to relative offset, not absolute address)
  28  *
  29  * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
  30  */
  31 public class GOTO extends GotoInstruction implements VariableLengthInstruction {
  32   /**
  33    * Empty constructor needed for the Class.newInstance() statement in
  34    * Instruction.readInstruction(). Not to be used otherwise.
  35    */
  36   GOTO() {}
  37 
  38   public GOTO(InstructionHandle target) {
  39     super(com.sun.org.apache.bcel.internal.Constants.GOTO, target);
  40   }
  41 
  42   /**
  43    * Dump instruction as byte code to stream out.
  44    * @param out Output stream
  45    */
  46   public void dump(DataOutputStream out) throws IOException {
  47     index = getTargetOffset();
  48     if(opcode == com.sun.org.apache.bcel.internal.Constants.GOTO)
  49       super.dump(out);
  50     else { // GOTO_W
  51       index = getTargetOffset();
  52       out.writeByte(opcode);
  53       out.writeInt(index);
  54     }
  55   }
  56 
  57   /** Called in pass 2 of InstructionList.setPositions() in order to update
  58    * the branch target, that may shift due to variable length instructions.
  59    */
  60   protected int updatePosition(int offset, int max_offset) {
  61     int i = getTargetOffset(); // Depending on old position value
  62 
  63     position += offset; // Position may be shifted by preceding expansions
  64 
  65     if(Math.abs(i) >= (32767 - max_offset)) { // to large for short (estimate)
  66       opcode = com.sun.org.apache.bcel.internal.Constants.GOTO_W;
  67       length = 5;
  68       return 2; // 5 - 3
  69     }
  70 
  71     return 0;
  72   }
  73 
  74   /**
  75    * Call corresponding visitor method(s). The order is:
  76    * Call visitor methods of implemented interfaces first, then
  77    * call methods according to the class hierarchy in descending order,
  78    * i.e., the most specific visitXXX() call comes last.
  79    *
  80    * @param v Visitor object
  81    */
  82   public void accept(Visitor v) {
  83     v.visitVariableLengthInstruction(this);
  84     v.visitUnconditionalBranch(this);
  85     v.visitBranchInstruction(this);
  86     v.visitGotoInstruction(this);
  87     v.visitGOTO(this);
  88   }
  89 }