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 java.util.Arrays; 022 023import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode; 024import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager; 025 026/** 027 * Table switch instruction form. 028 */ 029public class TableSwitchForm extends SwitchForm { 030 031 /** 032 * Constructs a new instance with the specified opcode, name, operandType and rewrite. 033 * 034 * @param opcode index corresponding to the opcode's value. 035 * @param name String printable name of the opcode. 036 */ 037 public TableSwitchForm(final int opcode, final String name) { 038 super(opcode, name); 039 } 040 041 /* 042 * (non-Javadoc) 043 * 044 * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.SwitchForm#setByteCodeOperands(org.apache.commons. 045 * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager, int) 046 */ 047 @Override 048 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) { 049 final int caseCount = operandManager.nextCaseCount(); 050 final int defaultPc = operandManager.nextLabel(); 051 int caseValue = -1; 052 caseValue = operandManager.nextCaseValues(); 053 054 final int[] casePcs = new int[caseCount]; 055 Arrays.setAll(casePcs, i -> operandManager.nextLabel()); 056 057 final int[] labelsArray = new int[caseCount + 1]; 058 labelsArray[0] = defaultPc; 059 System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1); 060 byteCode.setByteCodeTargets(labelsArray); 061 062 final int lowValue = caseValue; 063 final int highValue = lowValue + caseCount - 1; 064 // All this gets dumped into the rewrite bytes of the 065 // poor bytecode. 066 067 // Unlike most byte codes, the TableSwitch is a 068 // variable-sized bytecode. Because of this, the 069 // rewrite array has to be defined here individually 070 // for each bytecode, rather than in the ByteCodeForm 071 // class. 072 073 // First, there's the bytecode. Then there are 0-3 074 // bytes of padding so that the first (default) 075 // label is on a 4-byte offset. 076 final int padLength = 3 - codeLength % 4; 077 final int rewriteSize = 1 + padLength + 4 // defaultbytes 078 + 4 // lowbyte 079 + 4 // highbyte 080 + 4 * casePcs.length; 081 082 final int[] newRewrite = new int[rewriteSize]; 083 int rewriteIndex = 0; 084 085 // Fill in what we can now 086 // opcode 087 newRewrite[rewriteIndex++] = byteCode.getOpcode(); 088 089 // padding 090 for (int index = 0; index < padLength; index++) { 091 newRewrite[rewriteIndex++] = 0; 092 } 093 094 // defaultbyte 095 // This gets overwritten by fixUpByteCodeTargets 096 newRewrite[rewriteIndex++] = -1; 097 newRewrite[rewriteIndex++] = -1; 098 newRewrite[rewriteIndex++] = -1; 099 newRewrite[rewriteIndex++] = -1; 100 101 // lowbyte 102 final int lowbyteIndex = rewriteIndex; 103 setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite); 104 rewriteIndex += 4; 105 106 // highbyte 107 final int highbyteIndex = rewriteIndex; 108 setRewrite4Bytes(highValue, highbyteIndex, newRewrite); 109 rewriteIndex += 4; 110 111 // jump offsets 112 // The case_pcs will get overwritten by fixUpByteCodeTargets 113 for (int index = 0; index < caseCount; index++) { 114 // offset 115 newRewrite[rewriteIndex++] = -1; 116 newRewrite[rewriteIndex++] = -1; 117 newRewrite[rewriteIndex++] = -1; 118 newRewrite[rewriteIndex++] = -1; 119 } 120 byteCode.setRewrite(newRewrite); 121 } 122}