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.CodeAttribute;
021import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
022
023/**
024 * This class implements the byte code form for those bytecodes which have label references (and only label references).
025 */
026public class LabelForm extends ByteCodeForm {
027
028    protected boolean widened;
029
030    public LabelForm(final int opcode, final String name, final int[] rewrite) {
031        super(opcode, name, rewrite);
032    }
033
034    public LabelForm(final int opcode, final String name, final int[] rewrite, final boolean widened) {
035        this(opcode, name, rewrite);
036        this.widened = widened;
037    }
038
039    /*
040     * (non-Javadoc)
041     *
042     * @see
043     * org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons.
044     * compress.harmony.unpack200.bytecode.ByteCode,
045     * org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute)
046     */
047    @Override
048    public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
049        // LabelForms need to fix up the target of label operations
050        final int originalTarget = byteCode.getByteCodeTargets()[0];
051        final int sourceIndex = byteCode.getByteCodeIndex();
052        final int absoluteInstructionTargetIndex = sourceIndex + originalTarget;
053        final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex)
054            .intValue();
055        final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue();
056        // The operand is the difference between the source instruction
057        // and the destination instruction.
058        byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0);
059        if (widened) {
060            byteCode.setNestedPositions(new int[][] {{0, 4}});
061        } else {
062            byteCode.setNestedPositions(new int[][] {{0, 2}});
063        }
064    }
065
066    /*
067     * (non-Javadoc)
068     *
069     * @see
070     * org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
071     * compress.harmony.unpack200.bytecode.ByteCode,
072     * org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
073     * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool)
074     */
075    @Override
076    public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager,
077        final int codeLength) {
078        byteCode.setByteCodeTargets(new int[] {operandManager.nextLabel()});
079        // The byte code operands actually get set later -
080        // once we have all the bytecodes - in fixUpByteCodeTarget().
081        return;
082    }
083}