    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 TableSwitchForm extends SwitchForm {
    023
    024    public TableSwitchForm(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        int case_value = -1;
    042        case_value = operandManager.nextCaseValues();
    043
    044        final int case_pcs[] = new int[case_count];
    045        for (int index = 0; index < case_count; index++) {
    046            case_pcs[index] = operandManager.nextLabel();
    047        }
    048
    049        final int[] labelsArray = new int[case_count + 1];
    050        labelsArray[0] = default_pc;
    051        for (int index = 1; index < case_count + 1; index++) {
    052            labelsArray[index] = case_pcs[index - 1];
    053        }
    054        byteCode.setByteCodeTargets(labelsArray);
    055
    056        final int lowValue = case_value;
    057        final int highValue = lowValue + case_count - 1;
    058        // All this gets dumped into the rewrite bytes of the
    059        // poor bytecode.
    060
    061        // Unlike most byte codes, the TableSwitch is a
    062        // variable-sized bytecode. Because of this, the
    063        // rewrite array has to be defined here individually
    064        // for each bytecode, rather than in the ByteCodeForm
    065        // class.
    066
    067        // First, there's the bytecode. Then there are 0-3
    068        // bytes of padding so that the first (default)
    069        // label is on a 4-byte offset.
    070        final int padLength = 3 - (codeLength % 4);
    071        final int rewriteSize = 1 + padLength + 4 // defaultbytes
    072            + 4 // lowbyte
    073            + 4 // highbyte
    074            + (4 * case_pcs.length);
    075
    076        final int[] newRewrite = new int[rewriteSize];
    077        int rewriteIndex = 0;
    078
    079        // Fill in what we can now
    080        // opcode
    081        newRewrite[rewriteIndex++] = byteCode.getOpcode();
    082
    083        // padding
    084        for (int index = 0; index < padLength; index++) {
    085            newRewrite[rewriteIndex++] = 0;
    086        }
    087
    088        // defaultbyte
    089        // This gets overwritten by fixUpByteCodeTargets
    090        newRewrite[rewriteIndex++] = -1;
    091        newRewrite[rewriteIndex++] = -1;
    092        newRewrite[rewriteIndex++] = -1;
    093        newRewrite[rewriteIndex++] = -1;
    094
    095        // lowbyte
    096        final int lowbyteIndex = rewriteIndex;
    097        setRewrite4Bytes(lowValue, lowbyteIndex, newRewrite);
    098        rewriteIndex += 4;
    099
    100        // highbyte
    101        final int highbyteIndex = rewriteIndex;
    102        setRewrite4Bytes(highValue, highbyteIndex, newRewrite);
    103        rewriteIndex += 4;
    104
    105        // jump offsets
    106        // The case_pcs will get overwritten by fixUpByteCodeTargets
    107        for (int index = 0; index < case_count; index++) {
    108            // offset
    109            newRewrite[rewriteIndex++] = -1;
    110            newRewrite[rewriteIndex++] = -1;
    111            newRewrite[rewriteIndex++] = -1;
    112            newRewrite[rewriteIndex++] = -1;
    113        }
    114        byteCode.setRewrite(newRewrite);
    115    }
    116}