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 LookupSwitchForm extends SwitchForm {
023
024    public LookupSwitchForm(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        final int case_values[] = new int[case_count];
042        for (int index = 0; index < case_count; index++) {
043            case_values[index] = operandManager.nextCaseValues();
044        }
045        final int case_pcs[] = new int[case_count];
046        for (int index = 0; index < case_count; index++) {
047            case_pcs[index] = operandManager.nextLabel();
048        }
049
050        final int[] labelsArray = new int[case_count + 1];
051        labelsArray[0] = default_pc;
052        for (int index = 1; index < case_count + 1; index++) {
053            labelsArray[index] = case_pcs[index - 1];
054        }
055        byteCode.setByteCodeTargets(labelsArray);
056
057        // All this gets dumped into the rewrite bytes of the
058        // poor bytecode.
059
060        // Unlike most byte codes, the LookupSwitch is a
061        // variable-sized bytecode. Because of this, the
062        // rewrite array has to be defined here individually
063        // for each bytecode, rather than in the ByteCodeForm
064        // class.
065
066        // First, there's the bytecode. Then there are 0-3
067        // bytes of padding so that the first (default)
068        // label is on a 4-byte offset.
069        final int padLength = 3 - (codeLength % 4);
070        final int rewriteSize = 1 + padLength + 4 // defaultbytes
071            + 4 // npairs
072            + (4 * case_values.length) + (4 * case_pcs.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        // npairs
094        final int npairsIndex = rewriteIndex;
095        setRewrite4Bytes(case_values.length, npairsIndex, newRewrite);
096        rewriteIndex += 4;
097
098        // match-offset pairs
099        // The case_values aren't overwritten, but the
100        // case_pcs will get overwritten by fixUpByteCodeTargets
101        for (int index = 0; index < case_values.length; index++) {
102            // match
103            setRewrite4Bytes(case_values[index], rewriteIndex, newRewrite);
104            rewriteIndex += 4;
105            // offset
106            newRewrite[rewriteIndex++] = -1;
107            newRewrite[rewriteIndex++] = -1;
108            newRewrite[rewriteIndex++] = -1;
109            newRewrite[rewriteIndex++] = -1;
110        }
111        byteCode.setRewrite(newRewrite);
112    }
113}