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 LookupSwitchForm extends SwitchForm { 025 026 public LookupSwitchForm(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 final int[] caseValues = new int[caseCount]; 044 Arrays.setAll(caseValues, i -> operandManager.nextCaseValues()); 045 final int[] casePcs = new int[caseCount]; 046 Arrays.setAll(casePcs, i -> operandManager.nextLabel()); 047 048 final int[] labelsArray = new int[caseCount + 1]; 049 labelsArray[0] = defaultPc; 050 System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1); 051 byteCode.setByteCodeTargets(labelsArray); 052 053 // All this gets dumped into the rewrite bytes of the 054 // poor bytecode. 055 056 // Unlike most byte codes, the LookupSwitch is a 057 // variable-sized bytecode. Because of this, the 058 // rewrite array has to be defined here individually 059 // for each bytecode, rather than in the ByteCodeForm 060 // class. 061 062 // First, there's the bytecode. Then there are 0-3 063 // bytes of padding so that the first (default) 064 // label is on a 4-byte offset. 065 final int padLength = 3 - (codeLength % 4); 066 final int rewriteSize = 1 + padLength + 4 // defaultbytes 067 + 4 // npairs 068 + (4 * caseValues.length) + (4 * casePcs.length); 069 070 final int[] newRewrite = new int[rewriteSize]; 071 int rewriteIndex = 0; 072 073 // Fill in what we can now 074 // opcode 075 newRewrite[rewriteIndex++] = byteCode.getOpcode(); 076 077 // padding 078 for (int index = 0; index < padLength; index++) { 079 newRewrite[rewriteIndex++] = 0; 080 } 081 082 // defaultbyte 083 // This gets overwritten by fixUpByteCodeTargets 084 newRewrite[rewriteIndex++] = -1; 085 newRewrite[rewriteIndex++] = -1; 086 newRewrite[rewriteIndex++] = -1; 087 newRewrite[rewriteIndex++] = -1; 088 089 // npairs 090 final int npairsIndex = rewriteIndex; 091 setRewrite4Bytes(caseValues.length, npairsIndex, newRewrite); 092 rewriteIndex += 4; 093 094 // match-offset pairs 095 // The caseValues aren't overwritten, but the 096 // casePcs will get overwritten by fixUpByteCodeTargets 097 for (final int caseValue : caseValues) { 098 // match 099 setRewrite4Bytes(caseValue, rewriteIndex, newRewrite); 100 rewriteIndex += 4; 101 // offset 102 newRewrite[rewriteIndex++] = -1; 103 newRewrite[rewriteIndex++] = -1; 104 newRewrite[rewriteIndex++] = -1; 105 newRewrite[rewriteIndex++] = -1; 106 } 107 byteCode.setRewrite(newRewrite); 108 } 109}