001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.compress.harmony.unpack200.bytecode.forms; 018 019import java.util.Arrays; 020 021import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode; 022import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager; 023 024public class TableSwitchForm extends SwitchForm { 025 026 public TableSwitchForm(final int opcode, final String name) { 027 super(opcode, name); 028 } 029 030 /* 031 * (non-Javadoc) 032 * 033 * @see 034 * org.apache.commons.compress.harmony.unpack200.bytecode.forms.SwitchForm#setByteCodeOperands(org.apache.commons. 035 * compress.harmony.unpack200.bytecode.ByteCode, 036 * org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager, int) 037 */ 038 @Override 039 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, 040 final int codeLength) { 041 final int caseCount = operandManager.nextCaseCount(); 042 final int defaultPc = operandManager.nextLabel(); 043 int caseValue = -1; 044 caseValue = operandManager.nextCaseValues(); 045 046 final int[] casePcs = new int[caseCount]; 047 Arrays.setAll(casePcs, i -> operandManager.nextLabel()); 048 049 final int[] labelsArray = new int[caseCount + 1]; 050 labelsArray[0] = defaultPc; 051 System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1); 052 byteCode.setByteCodeTargets(labelsArray); 053 054 final int lowValue = caseValue; 055 final int highValue = lowValue + caseCount - 1; 056 // All this gets dumped into the rewrite bytes of the 057 // poor bytecode. 058 059 // Unlike most byte codes, the TableSwitch is a 060 // variable-sized bytecode. Because of this, the 061 // rewrite array has to be defined here individually 062 // for each bytecode, rather than in the ByteCodeForm 063 // class. 064 065 // First, there's the bytecode. Then there are 0-3 066 // bytes of padding so that the first (default) 067 // label is on a 4-byte offset. 068 final int padLength = 3 - codeLength % 4; 069 final int rewriteSize = 1 + padLength + 4 // defaultbytes 070 + 4 // lowbyte 071 + 4 // highbyte 072 + 4 * casePcs.length; 073 074 final int[] newRewrite = new int[rewriteSize]; 075 int rewriteIndex = 0; 076 077 // Fill in what we can now 078 // opcode 079 newRewrite[rewriteIndex++] = byteCode.getOpcode(); 080 081 // padding 082 for (int index = 0; index < padLength; index++) { 083 newRewrite[rewriteIndex++] = 0; 084 } 085 086 // defaultbyte 087 // This gets overwritten by fixUpByteCodeTargets 088 newRewrite[rewriteIndex++] = -1; 089 newRewrite[rewriteIndex++] = -1; 090 newRewrite[rewriteIndex++] = -1; 091 newRewrite[rewriteIndex++] = -1; 092 093 // lowbyte 094 final int lowbyteIndex = rewriteIndex; 095 setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite); 096 rewriteIndex += 4; 097 098 // highbyte 099 final int highbyteIndex = rewriteIndex; 100 setRewrite4Bytes(highValue, highbyteIndex, newRewrite); 101 rewriteIndex += 4; 102 103 // jump offsets 104 // The case_pcs will get overwritten by fixUpByteCodeTargets 105 for (int index = 0; index < caseCount; index++) { 106 // offset 107 newRewrite[rewriteIndex++] = -1; 108 newRewrite[rewriteIndex++] = -1; 109 newRewrite[rewriteIndex++] = -1; 110 newRewrite[rewriteIndex++] = -1; 111 } 112 byteCode.setRewrite(newRewrite); 113 } 114}