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 org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode; 020import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager; 021 022public class TableSwitchForm extends SwitchForm { 023 024 public TableSwitchForm(final int opcode, final String name) { 025 super(opcode, name); 026 } 027 028 /* 029 * (non-Javadoc) 030 * 031 * @see 032 * org.apache.commons.compress.harmony.unpack200.bytecode.forms.SwitchForm#setByteCodeOperands(org.apache.commons. 033 * compress.harmony.unpack200.bytecode.ByteCode, 034 * org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager, int) 035 */ 036 @Override 037 public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, 038 final int codeLength) { 039 final int case_count = operandManager.nextCaseCount(); 040 final int default_pc = operandManager.nextLabel(); 041 int case_value = -1; 042 case_value = operandManager.nextCaseValues(); 043 044 final int case_pcs[] = new int[case_count]; 045 for (int index = 0; index < case_count; index++) { 046 case_pcs[index] = operandManager.nextLabel(); 047 } 048 049 final int[] labelsArray = new int[case_count + 1]; 050 labelsArray[0] = default_pc; 051 for (int index = 1; index < case_count + 1; index++) { 052 labelsArray[index] = case_pcs[index - 1]; 053 } 054 byteCode.setByteCodeTargets(labelsArray); 055 056 final int lowValue = case_value; 057 final int highValue = lowValue + case_count - 1; 058 // All this gets dumped into the rewrite bytes of the 059 // poor bytecode. 060 061 // Unlike most byte codes, the TableSwitch is a 062 // variable-sized bytecode. Because of this, the 063 // rewrite array has to be defined here individually 064 // for each bytecode, rather than in the ByteCodeForm 065 // class. 066 067 // First, there's the bytecode. Then there are 0-3 068 // bytes of padding so that the first (default) 069 // label is on a 4-byte offset. 070 final int padLength = 3 - (codeLength % 4); 071 final int rewriteSize = 1 + padLength + 4 // defaultbytes 072 + 4 // lowbyte 073 + 4 // highbyte 074 + (4 * case_pcs.length); 075 076 final int[] newRewrite = new int[rewriteSize]; 077 int rewriteIndex = 0; 078 079 // Fill in what we can now 080 // opcode 081 newRewrite[rewriteIndex++] = byteCode.getOpcode(); 082 083 // padding 084 for (int index = 0; index < padLength; index++) { 085 newRewrite[rewriteIndex++] = 0; 086 } 087 088 // defaultbyte 089 // This gets overwritten by fixUpByteCodeTargets 090 newRewrite[rewriteIndex++] = -1; 091 newRewrite[rewriteIndex++] = -1; 092 newRewrite[rewriteIndex++] = -1; 093 newRewrite[rewriteIndex++] = -1; 094 095 // lowbyte 096 final int lowbyteIndex = rewriteIndex; 097 setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite); 098 rewriteIndex += 4; 099 100 // highbyte 101 final int highbyteIndex = rewriteIndex; 102 setRewrite4Bytes(highValue, highbyteIndex, newRewrite); 103 rewriteIndex += 4; 104 105 // jump offsets 106 // The case_pcs will get overwritten by fixUpByteCodeTargets 107 for (int index = 0; index < case_count; index++) { 108 // offset 109 newRewrite[rewriteIndex++] = -1; 110 newRewrite[rewriteIndex++] = -1; 111 newRewrite[rewriteIndex++] = -1; 112 newRewrite[rewriteIndex++] = -1; 113 } 114 byteCode.setRewrite(newRewrite); 115 } 116}