    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}