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 org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons.
043     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute)
044     */
045    @Override
046    public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
047        // LabelForms need to fix up the target of label operations
048        final int originalTarget = byteCode.getByteCodeTargets()[0];
049        final int sourceIndex = byteCode.getByteCodeIndex();
050        final int absoluteInstructionTargetIndex = sourceIndex + originalTarget;
051        final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex).intValue();
052        final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue();
053        // The operand is the difference between the source instruction
054        // and the destination instruction.
055        byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0);
056        if (widened) {
057            byteCode.setNestedPositions(new int[][] { { 0, 4 } });
058        } else {
059            byteCode.setNestedPositions(new int[][] { { 0, 2 } });
060        }
061    }
062
063    /*
064     * (non-Javadoc)
065     *
066     * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
067     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
068     * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool)
069     */
070    @Override
071    public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
072        byteCode.setByteCodeTargets(new int[] { operandManager.nextLabel() });
073        // The byte code operands actually get set later -
074        // once we have all the bytecodes - in fixUpByteCodeTarget().
075    }
076}