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 import org.apache.bcel.util.ByteSequence;
58
59 /***
60 * RET - Return from subroutine
61 *
62 * <PRE>Stack: ..., -> ..., address</PRE>
63 *
64 * @version $Id: RET.java,v 1.1.1.1 2001/10/29 20:00:25 jvanzyl Exp $
65 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66 */
67 public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
68 private boolean wide;
69 private int index; // index to local variable containg the return address
70
71 /***
72 * Empty constructor needed for the Class.newInstance() statement in
73 * Instruction.readInstruction(). Not to be used otherwise.
74 */
75 RET() {}
76
77 public RET(int index) {
78 super(org.apache.bcel.Constants.RET, (short)2);
79 setIndex(index); // May set wide as side effect
80 }
81
82 /***
83 * Dump instruction as byte code to stream out.
84 * @param out Output stream
85 */
86 public void dump(DataOutputStream out) throws IOException {
87 if(wide)
88 out.writeByte(org.apache.bcel.Constants.WIDE);
89
90 out.writeByte(opcode);
91
92 if(wide)
93 out.writeShort(index);
94 else
95 out.writeByte(index);
96 }
97
98 private final void setWide() {
99 if(wide = index > org.apache.bcel.Constants.MAX_BYTE)
100 length = 4; // Including the wide byte
101 else
102 length = 2;
103 }
104
105 /***
106 * Read needed data (e.g. index) from file.
107 */
108 protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
109 {
110 this.wide = wide;
111
112 if(wide) {
113 index = bytes.readUnsignedShort();
114 length = 4;
115 } else {
116 index = bytes.readUnsignedByte();
117 length = 2;
118 }
119 }
120
121 /***
122 * @return index of local variable containg the return address
123 */
124 public final int getIndex() { return index; }
125
126 /***
127 * Set index of local variable containg the return address
128 */
129 public final void setIndex(int n) {
130 if(n < 0)
131 throw new ClassGenException("Negative index value: " + n);
132
133 index = n;
134 setWide();
135 }
136
137 /***
138 * @return mnemonic for instruction
139 */
140 public String toString(boolean verbose) {
141 return super.toString(verbose) + " " + index;
142 }
143
144 /*** @return return address type
145 */
146 public Type getType(ConstantPoolGen cp) {
147 return ReturnaddressType.NO_TARGET;
148 }
149
150 /***
151 * Call corresponding visitor method(s). The order is:
152 * Call visitor methods of implemented interfaces first, then
153 * call methods according to the class hierarchy in descending order,
154 * i.e., the most specific visitXXX() call comes last.
155 *
156 * @param v Visitor object
157 */
158 public void accept(Visitor v) {
159 v.visitRET(this);
160 }
161 }
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