1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.generic;
18
19 import java.io.DataOutputStream;
20 import java.io.IOException;
21
22 import org.apache.bcel.util.ByteSequence;
23
24 /**
25 * RET - Return from subroutine
26 *
27 * <PRE>
28 * Stack: ... -> ...
29 * </PRE>
30 */
31 public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
32
33 private boolean wide;
34 private int index; // index to local variable containg the return address
35
36 /**
37 * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
38 */
39 RET() {
40 }
41
42 public RET(final int index) {
43 super(org.apache.bcel.Const.RET, (short) 2);
44 setIndex(index); // May set wide as side effect
45 }
46
47 /**
48 * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
49 * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
50 *
51 * @param v Visitor object
52 */
53 @Override
54 public void accept(final Visitor v) {
55 v.visitRET(this);
56 }
57
58 /**
59 * Dump instruction as byte code to stream out.
60 *
61 * @param out Output stream
62 */
63 @Override
64 public void dump(final DataOutputStream out) throws IOException {
65 if (wide) {
66 out.writeByte(org.apache.bcel.Const.WIDE);
67 }
68 out.writeByte(super.getOpcode());
69 if (wide) {
70 out.writeShort(index);
71 } else {
72 out.writeByte(index);
73 }
74 }
75
76 /**
77 * @return index of local variable containg the return address
78 */
79 @Override
80 public final int getIndex() {
81 return index;
82 }
83
84 /**
85 * @return return address type
86 */
87 @Override
88 public Type getType(final ConstantPoolGen cp) {
89 return ReturnaddressType.NO_TARGET;
90 }
91
92 /**
93 * Read needed data (e.g. index) from file.
94 */
95 @Override
96 protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
97 this.wide = wide;
98 if (wide) {
99 index = bytes.readUnsignedShort();
100 super.setLength(4);
101 } else {
102 index = bytes.readUnsignedByte();
103 super.setLength(2);
104 }
105 }
106
107 /**
108 * Sets index of local variable containg the return address
109 */
110 @Override
111 public final void setIndex(final int n) {
112 if (n < 0) {
113 throw new ClassGenException("Negative index value: " + n);
114 }
115 index = n;
116 setWide();
117 }
118
119 private void setWide() {
120 wide = index > org.apache.bcel.Const.MAX_BYTE;
121 if (wide) {
122 super.setLength(4); // Including the wide byte
123 } else {
124 super.setLength(2);
125 }
126 }
127
128 /**
129 * @return mnemonic for instruction
130 */
131 @Override
132 public String toString(final boolean verbose) {
133 return super.toString(verbose) + " " + index;
134 }
135 }