1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.bcel.generic;
20
21 import java.io.DataOutputStream;
22 import java.io.IOException;
23
24 import org.apache.bcel.util.ByteSequence;
25
26 /**
27 * RET - Return from subroutine
28 *
29 * <PRE>
30 * Stack: ... -> ...
31 * </PRE>
32 */
33 public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
34
35 private boolean wide;
36 private int index; // index to local variable containg the return address
37
38 /**
39 * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
40 */
41 RET() {
42 }
43
44 public RET(final int index) {
45 super(org.apache.bcel.Const.RET, (short) 2);
46 setIndex(index); // May set wide as side effect
47 }
48
49 /**
50 * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
51 * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
52 *
53 * @param v Visitor object
54 */
55 @Override
56 public void accept(final Visitor v) {
57 v.visitRET(this);
58 }
59
60 /**
61 * Dump instruction as byte code to stream out.
62 *
63 * @param out Output stream
64 */
65 @Override
66 public void dump(final DataOutputStream out) throws IOException {
67 if (wide) {
68 out.writeByte(org.apache.bcel.Const.WIDE);
69 }
70 out.writeByte(super.getOpcode());
71 if (wide) {
72 out.writeShort(index);
73 } else {
74 out.writeByte(index);
75 }
76 }
77
78 /**
79 * @return index of local variable containg the return address
80 */
81 @Override
82 public final int getIndex() {
83 return index;
84 }
85
86 /**
87 * @return return address type
88 */
89 @Override
90 public Type getType(final ConstantPoolGen cp) {
91 return ReturnaddressType.NO_TARGET;
92 }
93
94 /**
95 * Reads needed data (for example index) from file.
96 */
97 @Override
98 protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
99 this.wide = wide;
100 if (wide) {
101 index = bytes.readUnsignedShort();
102 super.setLength(4);
103 } else {
104 index = bytes.readUnsignedByte();
105 super.setLength(2);
106 }
107 }
108
109 /**
110 * Sets index of local variable containg the return address
111 */
112 @Override
113 public final void setIndex(final int n) {
114 if (n < 0) {
115 throw new ClassGenException("Negative index value: " + n);
116 }
117 index = n;
118 setWide();
119 }
120
121 private void setWide() {
122 wide = index > org.apache.bcel.Const.MAX_BYTE;
123 if (wide) {
124 super.setLength(4); // Including the wide byte
125 } else {
126 super.setLength(2);
127 }
128 }
129
130 /**
131 * @return mnemonic for instruction
132 */
133 @Override
134 public String toString(final boolean verbose) {
135 return super.toString(verbose) + " " + index;
136 }
137 }