    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}