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1   /*
2    * reserved comment block
3    * DO NOT REMOVE OR ALTER!
4    */
5   package com.sun.org.apache.bcel.internal.generic;
6   
7   /* ====================================================================
8    * The Apache Software License, Version 1.1
9    *
10   * Copyright (c) 2001 The Apache Software Foundation.  All rights
11   * reserved.
12   *
13   * Redistribution and use in source and binary forms, with or without
14   * modification, are permitted provided that the following conditions
15   * are met:
16   *
17   * 1. Redistributions of source code must retain the above copyright
18   *    notice, this list of conditions and the following disclaimer.
19   *
20   * 2. Redistributions in binary form must reproduce the above copyright
21   *    notice, this list of conditions and the following disclaimer in
22   *    the documentation and/or other materials provided with the
23   *    distribution.
24   *
25   * 3. The end-user documentation included with the redistribution,
26   *    if any, must include the following acknowledgment:
27   *       "This product includes software developed by the
28   *        Apache Software Foundation (http://www.apache.org/)."
29   *    Alternately, this acknowledgment may appear in the software itself,
30   *    if and wherever such third-party acknowledgments normally appear.
31   *
32   * 4. The names "Apache" and "Apache Software Foundation" and
33   *    "Apache BCEL" must not be used to endorse or promote products
34   *    derived from this software without prior written permission. For
35   *    written permission, please contact apache@apache.org.
36   *
37   * 5. Products derived from this software may not be called "Apache",
38   *    "Apache BCEL", nor may "Apache" appear in their name, without
39   *    prior written permission of the Apache Software Foundation.
40   *
41   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52   * SUCH DAMAGE.
53   * ====================================================================
54   *
55   * This software consists of voluntary contributions made by many
56   * individuals on behalf of the Apache Software Foundation.  For more
57   * information on the Apache Software Foundation, please see
58   * <http://www.apache.org/>.
59   */
60  import java.io.*;
61  import com.sun.org.apache.bcel.internal.util.ByteSequence;
62  
63  /**
64   * RET - Return from subroutine
65   *
66   * <PRE>Stack: ..., -&gt; ..., address</PRE>
67   *
68   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69   */
70  public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
71    private boolean wide;
72    private int     index; // index to local variable containg the return address
73  
74    /**
75     * Empty constructor needed for the Class.newInstance() statement in
76     * Instruction.readInstruction(). Not to be used otherwise.
77     */
78    RET() {}
79  
80    public RET(int index) {
81      super(com.sun.org.apache.bcel.internal.Constants.RET, (short)2);
82      setIndex(index);   // May set wide as side effect
83    }
84  
85    /**
86     * Dump instruction as byte code to stream out.
87     * @param out Output stream
88     */
89    public void dump(DataOutputStream out) throws IOException {
90      if(wide)
91        out.writeByte(com.sun.org.apache.bcel.internal.Constants.WIDE);
92  
93      out.writeByte(opcode);
94  
95      if(wide)
96        out.writeShort(index);
97      else
98        out.writeByte(index);
99    }
100 
101   private final void setWide() {
102     if(wide = index > com.sun.org.apache.bcel.internal.Constants.MAX_BYTE)
103       length = 4; // Including the wide byte
104     else
105       length = 2;
106   }
107 
108   /**
109    * Read needed data (e.g. index) from file.
110    */
111   protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
112   {
113     this.wide = wide;
114 
115     if(wide) {
116       index  = bytes.readUnsignedShort();
117       length = 4;
118     } else {
119       index = bytes.readUnsignedByte();
120       length = 2;
121     }
122   }
123 
124   /**
125    * @return index of local variable containg the return address
126    */
127   public final int getIndex() { return index; }
128 
129   /**
130    * Set index of local variable containg the return address
131    */
132   public final void setIndex(int n) {
133     if(n < 0)
134       throw new ClassGenException("Negative index value: " + n);
135 
136     index = n;
137     setWide();
138   }
139 
140   /**
141    * @return mnemonic for instruction
142    */
143   public String toString(boolean verbose) {
144     return super.toString(verbose) + " " + index;
145   }
146 
147   /** @return return address type
148    */
149   public Type getType(ConstantPoolGen cp) {
150       return ReturnaddressType.NO_TARGET;
151   }
152 
153   /**
154    * Call corresponding visitor method(s). The order is:
155    * Call visitor methods of implemented interfaces first, then
156    * call methods according to the class hierarchy in descending order,
157    * i.e., the most specific visitXXX() call comes last.
158    *
159    * @param v Visitor object
160    */
161   public void accept(Visitor v) {
162     v.visitRET(this);
163   }
164 }