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1 package org.apache.bcel.generic; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache BCEL" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * "Apache BCEL", nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 import java.io.*; 57 58 /*** 59 * GOTO - Branch always (to relative offset, not absolute address) 60 * 61 * @version $Id: GOTO.java,v 1.1.1.1 2001/10/29 20:00:13 jvanzyl Exp $ 62 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> 63 */ 64 public class GOTO extends GotoInstruction implements VariableLengthInstruction { 65 /*** 66 * Empty constructor needed for the Class.newInstance() statement in 67 * Instruction.readInstruction(). Not to be used otherwise. 68 */ 69 GOTO() {} 70 71 public GOTO(InstructionHandle target) { 72 super(org.apache.bcel.Constants.GOTO, target); 73 } 74 75 /*** 76 * Dump instruction as byte code to stream out. 77 * @param out Output stream 78 */ 79 public void dump(DataOutputStream out) throws IOException { 80 index = getTargetOffset(); 81 if(opcode == org.apache.bcel.Constants.GOTO) 82 super.dump(out); 83 else { // GOTO_W 84 index = getTargetOffset(); 85 out.writeByte(opcode); 86 out.writeInt(index); 87 } 88 } 89 90 /*** Called in pass 2 of InstructionList.setPositions() in order to update 91 * the branch target, that may shift due to variable length instructions. 92 */ 93 protected int updatePosition(int offset, int max_offset) { 94 int i = getTargetOffset(); // Depending on old position value 95 96 position += offset; // Position may be shifted by preceding expansions 97 98 if(Math.abs(i) >= (32767 - max_offset)) { // to large for short (estimate) 99 opcode = org.apache.bcel.Constants.GOTO_W; 100 length = 5; 101 return 2; // 5 - 3 102 } 103 104 return 0; 105 } 106 107 /*** 108 * Call corresponding visitor method(s). The order is: 109 * Call visitor methods of implemented interfaces first, then 110 * call methods according to the class hierarchy in descending order, 111 * i.e., the most specific visitXXX() call comes last. 112 * 113 * @param v Visitor object 114 */ 115 public void accept(Visitor v) { 116 v.visitVariableLengthInstruction(this); 117 v.visitUnconditionalBranch(this); 118 v.visitBranchInstruction(this); 119 v.visitGotoInstruction(this); 120 v.visitGOTO(this); 121 } 122 }

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