001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.commons.compress.harmony.unpack200.bytecode.forms;
020
021import org.apache.commons.compress.harmony.unpack200.bytecode.ByteCode;
022import org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute;
023import org.apache.commons.compress.harmony.unpack200.bytecode.OperandManager;
024
025/**
026 * This class implements the byte code form for those bytecodes which have label references (and only label references).
027 */
028public class LabelForm extends ByteCodeForm {
029
030    protected boolean widened;
031
032    /**
033     * Constructs a new instance with the specified opcode, name, operandType and rewrite.
034     *
035     * @param opcode  index corresponding to the opcode's value.
036     * @param name    String printable name of the opcode.
037     * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1.
038     */
039    public LabelForm(final int opcode, final String name, final int[] rewrite) {
040        super(opcode, name, rewrite);
041    }
042
043    /**
044     * Constructs a new instance with the specified opcode, name, operandType and rewrite.
045     *
046     * @param opcode  index corresponding to the opcode's value.
047     * @param name    String printable name of the opcode.
048     * @param rewrite Operand positions (which will later be rewritten in ByteCodes) are indicated by -1.
049     * @param widened TODO.
050     */
051    public LabelForm(final int opcode, final String name, final int[] rewrite, final boolean widened) {
052        this(opcode, name, rewrite);
053        this.widened = widened;
054    }
055
056    /*
057     * (non-Javadoc)
058     *
059     * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#fixUpByteCodeTarget(org.apache.commons.
060     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.CodeAttribute)
061     */
062    @Override
063    public void fixUpByteCodeTargets(final ByteCode byteCode, final CodeAttribute codeAttribute) {
064        // LabelForms need to fix up the target of label operations
065        final int originalTarget = byteCode.getByteCodeTargets()[0];
066        final int sourceIndex = byteCode.getByteCodeIndex();
067        final int absoluteInstructionTargetIndex = sourceIndex + originalTarget;
068        final int targetValue = codeAttribute.byteCodeOffsets.get(absoluteInstructionTargetIndex).intValue();
069        final int sourceValue = codeAttribute.byteCodeOffsets.get(sourceIndex).intValue();
070        // The operand is the difference between the source instruction
071        // and the destination instruction.
072        byteCode.setOperandSigned2Bytes(targetValue - sourceValue, 0);
073        if (widened) {
074            byteCode.setNestedPositions(new int[][] { { 0, 4 } });
075        } else {
076            byteCode.setNestedPositions(new int[][] { { 0, 2 } });
077        }
078    }
079
080    /*
081     * (non-Javadoc)
082     *
083     * @see org.apache.commons.compress.harmony.unpack200.bytecode.forms.ByteCodeForm#setByteCodeOperands(org.apache.commons.
084     * compress.harmony.unpack200.bytecode.ByteCode, org.apache.commons.compress.harmony.unpack200.bytecode.OperandTable,
085     * org.apache.commons.compress.harmony.unpack200.SegmentConstantPool)
086     */
087    @Override
088    public void setByteCodeOperands(final ByteCode byteCode, final OperandManager operandManager, final int codeLength) {
089        byteCode.setByteCodeTargets(new int[] { operandManager.nextLabel() });
090        // The byte code operands actually get set later -
091        // once we have all the bytecodes - in fixUpByteCodeTarget().
092    }
093}