    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.bcel.generic;
    018
    019import java.io.DataOutputStream;
    020import java.io.IOException;
    021
    022import org.apache.bcel.Const;
    023import org.apache.bcel.util.ByteSequence;
    024
    025/**
    026 * IINC - Increment local variable by constant
    027 */
    028public class IINC extends LocalVariableInstruction {
    029
    030    private boolean wide;
    031    private int c;
    032
    033    /**
    034     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
    035     */
    036    IINC() {
    037    }
    038
    039    /**
    040     * @param n index of local variable
    041     * @param c increment factor
    042     */
    043    public IINC(final int n, final int c) {
    044        // Default behavior of LocalVariableInstruction causes error
    045        super.setOpcode(Const.IINC);
    046        super.setLength((short) 3);
    047        setIndex(n); // May set wide as side effect
    048        setIncrement(c);
    049    }
    050
    051    /**
    052     * Calls corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
    053     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
    054     *
    055     * @param v Visitor object
    056     */
    057    @Override
    058    public void accept(final Visitor v) {
    059        v.visitLocalVariableInstruction(this);
    060        v.visitIINC(this);
    061    }
    062
    063    /**
    064     * Dumps instruction as byte code to stream out.
    065     *
    066     * @param out Output stream
    067     */
    068    @Override
    069    public void dump(final DataOutputStream out) throws IOException {
    070        if (wide) {
    071            out.writeByte(Const.WIDE);
    072        }
    073        out.writeByte(super.getOpcode());
    074        if (wide) {
    075            out.writeShort(super.getIndex());
    076            out.writeShort(c);
    077        } else {
    078            out.writeByte(super.getIndex());
    079            out.writeByte(c);
    080        }
    081    }
    082
    083    /**
    084     * @return increment factor
    085     */
    086    public final int getIncrement() {
    087        return c;
    088    }
    089
    090    /**
    091     * @return int type
    092     */
    093    @Override
    094    public Type getType(final ConstantPoolGen cp) {
    095        return Type.INT;
    096    }
    097
    098    /**
    099     * Reads needed data (e.g. index) from file.
    100     */
    101    @Override
    102    protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
    103        this.wide = wide;
    104        if (wide) {
    105            super.setLength(6);
    106            super.setIndexOnly(bytes.readUnsignedShort());
    107            c = bytes.readShort();
    108        } else {
    109            super.setLength(3);
    110            super.setIndexOnly(bytes.readUnsignedByte());
    111            c = bytes.readByte();
    112        }
    113    }
    114
    115    /**
    116     * Sets increment factor.
    117     */
    118    public final void setIncrement(final int c) {
    119        this.c = c;
    120        setWide();
    121    }
    122
    123    /**
    124     * Sets index of local variable.
    125     */
    126    @Override
    127    public final void setIndex(final int n) {
    128        if (n < 0) {
    129            throw new ClassGenException("Negative index value: " + n);
    130        }
    131        super.setIndexOnly(n);
    132        setWide();
    133    }
    134
    135    private void setWide() {
    136        wide = super.getIndex() > Const.MAX_BYTE;
    137        if (c > 0) {
    138            wide = wide || c > Byte.MAX_VALUE;
    139        } else {
    140            wide = wide || c < Byte.MIN_VALUE;
    141        }
    142        if (wide) {
    143            super.setLength(6); // wide byte included
    144        } else {
    145            super.setLength(3);
    146        }
    147    }
    148
    149    /**
    150     * Returns mnemonic for instruction.
    151     *
    152     * @return mnemonic for instruction.
    153     */
    154    @Override
    155    public String toString(final boolean verbose) {
    156        return super.toString(verbose) + " " + c;
    157    }
    158}