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}