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.commons.compress.harmony.unpack200.bytecode.forms;
20
21 import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
22 import org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute;
23 import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
24
25 /**
26 * This class implements the byte code form for those bytecodes which have label references (and only label references).
27 */
28 public class LabelForm extends ByteCodeForm {
29
30 protected boolean widened;
31
32 /**
33 * Constructs a new instance with the specified opcode, name, operandType and rewrite.
34 *
35 * @param opcode index corresponding to the opcode's value.
36 * @param name String printable name of the opcode.
37 * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1.
38 */
39 public LabelForm(final int opcode, final String name, final int[] rewrite) {
40 super(opcode, name, rewrite);
41 }
42
43 /**
44 * Constructs a new instance with the specified opcode, name, operandType and rewrite.
45 *
46 * @param opcode index corresponding to the opcode's value.
47 * @param name String printable name of the opcode.
48 * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1.
49 * @param widened TODO.
50 */
51 public LabelForm(final int opcode, final String name, final int[] rewrite, final boolean widened) {
52 this(opcode, name, rewrite);
53 this.widened = widened;
54 }
55
56 /*
57 * (non-Javadoc)
58 *
59 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons.
60 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute)
61 */
62 @Override
63 public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
64 // LabelForms need to fix up the target of label operations
65 final int originalTarget = byteCode.getByteCodeTargets()[0];
66 final int sourceIndex = byteCode.getByteCodeIndex();
67 final int absoluteInstructionTargetIndex = sourceIndex + originalTarget;
68 final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex).intValue();
69 final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue();
70 // The operand is the difference between the source instruction
71 // and the destination instruction.
72 byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0);
73 if (widened) {
74 byteCode.setNestedPositions(new int[][] { { 0, 4 } });
75 } else {
76 byteCode.setNestedPositions(new int[][] { { 0, 2 } });
77 }
78 }
79
80 /*
81 * (non-Javadoc)
82 *
83 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
84 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
85 * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool)
86 */
87 @Override
88 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
89 byteCode.setByteCodeTargets(new int[] { operandManager.nextLabel() });
90 // The byte code operands actually get set later -
91 // once we have all the bytecodes - in fixUpByteCodeTarget().
92 }
93 }