    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 org.apache.commons.compress.harmony.unpack200.bytecode.forms.SwitchForm#setByteCodeOperands(org.apache.commons.
    034     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager, int)
    035     */
    036    @Override
    037    public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
    038        final int caseCount = operandManager.nextCaseCount();
    039        final int defaultPc = operandManager.nextLabel();
    040        int caseValue = -1;
    041        caseValue = operandManager.nextCaseValues();
    042
    043        final int[] casePcs = new int[caseCount];
    044        Arrays.setAll(casePcs, i -> operandManager.nextLabel());
    045
    046        final int[] labelsArray = new int[caseCount + 1];
    047        labelsArray[0] = defaultPc;
    048        System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1);
    049        byteCode.setByteCodeTargets(labelsArray);
    050
    051        final int lowValue = caseValue;
    052        final int highValue = lowValue + caseCount - 1;
    053        // All this gets dumped into the rewrite bytes of the
    054        // poor bytecode.
    055
    056        // Unlike most byte codes, the TableSwitch 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 // lowbyte
    068                + 4 // highbyte
    069                + 4 * casePcs.length;
    070
    071        final int[] newRewrite = new int[rewriteSize];
    072        int rewriteIndex = 0;
    073
    074        // Fill in what we can now
    075        // opcode
    076        newRewrite[rewriteIndex++] = byteCode.getOpcode();
    077
    078        // padding
    079        for (int index = 0; index < padLength; index++) {
    080            newRewrite[rewriteIndex++] = 0;
    081        }
    082
    083        // defaultbyte
    084        // This gets overwritten by fixUpByteCodeTargets
    085        newRewrite[rewriteIndex++] = -1;
    086        newRewrite[rewriteIndex++] = -1;
    087        newRewrite[rewriteIndex++] = -1;
    088        newRewrite[rewriteIndex++] = -1;
    089
    090        // lowbyte
    091        final int lowbyteIndex = rewriteIndex;
    092        setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite);
    093        rewriteIndex += 4;
    094
    095        // highbyte
    096        final int highbyteIndex = rewriteIndex;
    097        setRewrite4Bytes(highValue, highbyteIndex, newRewrite);
    098        rewriteIndex += 4;
    099
    100        // jump offsets
    101        // The case_pcs will get overwritten by fixUpByteCodeTargets
    102        for (int index = 0; index < caseCount; index++) {
    103            // offset
    104            newRewrite[rewriteIndex++] = -1;
    105            newRewrite[rewriteIndex++] = -1;
    106            newRewrite[rewriteIndex++] = -1;
    107            newRewrite[rewriteIndex++] = -1;
    108        }
    109        byteCode.setRewrite(newRewrite);
    110    }
    111}