    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 LookupSwitchForm extends SwitchForm {
    025
    026    public LookupSwitchForm(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        final int[] caseValues = new int[caseCount];
    044        Arrays.setAll(caseValues, i -> operandManager.nextCaseValues());
    045        final int[] casePcs = new int[caseCount];
    046        Arrays.setAll(casePcs, i -> operandManager.nextLabel());
    047
    048        final int[] labelsArray = new int[caseCount + 1];
    049        labelsArray[0] = defaultPc;
    050        System.arraycopy(casePcs, 0, labelsArray, 1, caseCount + 1 - 1);
    051        byteCode.setByteCodeTargets(labelsArray);
    052
    053        // All this gets dumped into the rewrite bytes of the
    054        // poor bytecode.
    055
    056        // Unlike most byte codes, the LookupSwitch 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 // npairs
    068            + (4 * caseValues.length) + (4 * casePcs.length);
    069
    070        final int[] newRewrite = new int[rewriteSize];
    071        int rewriteIndex = 0;
    072
    073        // Fill in what we can now
    074        // opcode
    075        newRewrite[rewriteIndex++] = byteCode.getOpcode();
    076
    077        // padding
    078        for (int index = 0; index < padLength; index++) {
    079            newRewrite[rewriteIndex++] = 0;
    080        }
    081
    082        // defaultbyte
    083        // This gets overwritten by fixUpByteCodeTargets
    084        newRewrite[rewriteIndex++] = -1;
    085        newRewrite[rewriteIndex++] = -1;
    086        newRewrite[rewriteIndex++] = -1;
    087        newRewrite[rewriteIndex++] = -1;
    088
    089        // npairs
    090        final int npairsIndex = rewriteIndex;
    091        setRewrite4Bytes(caseValues.length, npairsIndex, newRewrite);
    092        rewriteIndex += 4;
    093
    094        // match-offset pairs
    095        // The caseValues aren't overwritten, but the
    096        // casePcs will get overwritten by fixUpByteCodeTargets
    097        for (final int caseValue : caseValues) {
    098            // match
    099            setRewrite4Bytes(caseValue, rewriteIndex, newRewrite);
    100            rewriteIndex += 4;
    101            // offset
    102            newRewrite[rewriteIndex++] = -1;
    103            newRewrite[rewriteIndex++] = -1;
    104            newRewrite[rewriteIndex++] = -1;
    105            newRewrite[rewriteIndex++] = -1;
    106        }
    107        byteCode.setRewrite(newRewrite);
    108    }
    109}