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.commons.compress.harmony.unpack200.bytecode.forms;
18
19 import java.util.Arrays;
20
21 import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
22 import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
23
24 public class TableSwitchForm extends SwitchForm {
25
26 public TableSwitchForm(final int opcode, final String name) {
27 super(opcode, name);
28 }
29
30 /*
31 * (non-Javadoc)
32 *
33 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.SwitchForm#setByteCodeOperands(org.apache.commons.
34 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager, int)
35 */
36 @Override
37 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
38 final int caseCount = operandManager.nextCaseCount();
39 final int defaultPc = operandManager.nextLabel();
40 int caseValue = -1;
41 caseValue = operandManager.nextCaseValues();
42
43 final int[] casePcs = new int[caseCount];
44 Arrays.setAll(casePcs, i -> operandManager.nextLabel());
45
46 final int[] labelsArray = new int[caseCount + 1];
47 labelsArray[0] = defaultPc;
48 System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1);
49 byteCode.setByteCodeTargets(labelsArray);
50
51 final int lowValue = caseValue;
52 final int highValue = lowValue + caseCount - 1;
53 // All this gets dumped into the rewrite bytes of the
54 // poor bytecode.
55
56 // Unlike most byte codes, the TableSwitch is a
57 // variable-sized bytecode. Because of this, the
58 // rewrite array has to be defined here individually
59 // for each bytecode, rather than in the ByteCodeForm
60 // class.
61
62 // First, there's the bytecode. Then there are 0-3
63 // bytes of padding so that the first (default)
64 // label is on a 4-byte offset.
65 final int padLength = 3 - codeLength % 4;
66 final int rewriteSize = 1 + padLength + 4 // defaultbytes
67 + 4 // lowbyte
68 + 4 // highbyte
69 + 4 * casePcs.length;
70
71 final int[] newRewrite = new int[rewriteSize];
72 int rewriteIndex = 0;
73
74 // Fill in what we can now
75 // opcode
76 newRewrite[rewriteIndex++] = byteCode.getOpcode();
77
78 // padding
79 for (int index = 0; index < padLength; index++) {
80 newRewrite[rewriteIndex++] = 0;
81 }
82
83 // defaultbyte
84 // This gets overwritten by fixUpByteCodeTargets
85 newRewrite[rewriteIndex++] = -1;
86 newRewrite[rewriteIndex++] = -1;
87 newRewrite[rewriteIndex++] = -1;
88 newRewrite[rewriteIndex++] = -1;
89
90 // lowbyte
91 final int lowbyteIndex = rewriteIndex;
92 setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite);
93 rewriteIndex += 4;
94
95 // highbyte
96 final int highbyteIndex = rewriteIndex;
97 setRewrite4Bytes(highValue, highbyteIndex, newRewrite);
98 rewriteIndex += 4;
99
100 // jump offsets
101 // The case_pcs will get overwritten by fixUpByteCodeTargets
102 for (int index = 0; index < caseCount; index++) {
103 // offset
104 newRewrite[rewriteIndex++] = -1;
105 newRewrite[rewriteIndex++] = -1;
106 newRewrite[rewriteIndex++] = -1;
107 newRewrite[rewriteIndex++] = -1;
108 }
109 byteCode.setRewrite(newRewrite);
110 }
111 }