001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * https://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.commons.compress.harmony.unpack200.bytecode.forms; 020 021import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode; 022import org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute; 023import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager; 024 025/** 026 * This class implements the byte code form for those bytecodes which have label references (and only label references). 027 */ 028public class LabelForm extends ByteCodeForm { 029 030 protected boolean widened; 031 032 /** 033 * Constructs a new instance with the specified opcode, name, operandType and rewrite. 034 * 035 * @param opcode index corresponding to the opcode's value. 036 * @param name String printable name of the opcode. 037 * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1. 038 */ 039 public LabelForm(final int opcode, final String name, final int[] rewrite) { 040 super(opcode, name, rewrite); 041 } 042 043 /** 044 * Constructs a new instance with the specified opcode, name, operandType and rewrite. 045 * 046 * @param opcode index corresponding to the opcode's value. 047 * @param name String printable name of the opcode. 048 * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1. 049 * @param widened TODO. 050 */ 051 public LabelForm(final int opcode, final String name, final int[] rewrite, final boolean widened) { 052 this(opcode, name, rewrite); 053 this.widened = widened; 054 } 055 056 /* 057 * (non-Javadoc) 058 * 059 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons. 060 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute) 061 */ 062 @Override 063 public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) { 064 // LabelForms need to fix up the target of label operations 065 final int originalTarget = byteCode.getByteCodeTargets()[0]; 066 final int sourceIndex = byteCode.getByteCodeIndex(); 067 final int absoluteInstructionTargetIndex = sourceIndex + originalTarget; 068 final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex).intValue(); 069 final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue(); 070 // The operand is the difference between the source instruction 071 // and the destination instruction. 072 byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0); 073 if (widened) { 074 byteCode.setNestedPositions(new int[][] { { 0, 4 } }); 075 } else { 076 byteCode.setNestedPositions(new int[][] { { 0, 2 } }); 077 } 078 } 079 080 /* 081 * (non-Javadoc) 082 * 083 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons. 084 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable, 085 * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool) 086 */ 087 @Override 088 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) { 089 byteCode.setByteCodeTargets(new int[] { operandManager.nextLabel() }); 090 // The byte code operands actually get set later - 091 // once we have all the bytecodes - in fixUpByteCodeTarget(). 092 } 093}