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 org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
20 import org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute;
21 import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
22
23 /**
24 * This class implements the byte code form for those bytecodes which have label references (and only label references).
25 */
26 public class LabelForm extends ByteCodeForm {
27
28 protected boolean widened;
29
30 public LabelForm(final int opcode, final String name, final int[] rewrite) {
31 super(opcode, name, rewrite);
32 }
33
34 public LabelForm(final int opcode, final String name, final int[] rewrite, final boolean widened) {
35 this(opcode, name, rewrite);
36 this.widened = widened;
37 }
38
39 /*
40 * (non-Javadoc)
41 *
42 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons.
43 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute)
44 */
45 @Override
46 public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
47 // LabelForms need to fix up the target of label operations
48 final int originalTarget = byteCode.getByteCodeTargets()[0];
49 final int sourceIndex = byteCode.getByteCodeIndex();
50 final int absoluteInstructionTargetIndex = sourceIndex + originalTarget;
51 final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex).intValue();
52 final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue();
53 // The operand is the difference between the source instruction
54 // and the destination instruction.
55 byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0);
56 if (widened) {
57 byteCode.setNestedPositions(new int[][] { { 0, 4 } });
58 } else {
59 byteCode.setNestedPositions(new int[][] { { 0, 2 } });
60 }
61 }
62
63 /*
64 * (non-Javadoc)
65 *
66 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
67 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
68 * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool)
69 */
70 @Override
71 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
72 byteCode.setByteCodeTargets(new int[] { operandManager.nextLabel() });
73 // The byte code operands actually get set later -
74 // once we have all the bytecodes - in fixUpByteCodeTarget().
75 }
76 }