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 *
017 */
018package org.apache.bcel.generic;
019
020import java.io.DataOutputStream;
021import java.io.IOException;
022
023import org.apache.bcel.util.ByteSequence;
024
025/**
026 * IINC - Increment local variable by constant
027 *
028 */
029public class IINC extends LocalVariableInstruction {
030
031    private boolean wide;
032    private int c;
033
034
035    /**
036     * Empty constructor needed for Instruction.readInstruction.
037     * Not to be used otherwise.
038     */
039    IINC() {
040    }
041
042
043    /**
044     * @param n index of local variable
045     * @param c increment factor
046     */
047    public IINC(final int n, final int c) {
048        super(); // Default behavior of LocalVariableInstruction causes error
049        super.setOpcode(org.apache.bcel.Const.IINC);
050        super.setLength((short) 3);
051        setIndex(n); // May set wide as side effect
052        setIncrement(c);
053    }
054
055
056    /**
057     * Dump instruction as byte code to stream out.
058     * @param out Output stream
059     */
060    @Override
061    public void dump( final DataOutputStream out ) throws IOException {
062        if (wide) {
063            out.writeByte(org.apache.bcel.Const.WIDE);
064        }
065        out.writeByte(super.getOpcode());
066        if (wide) {
067            out.writeShort(super.getIndex());
068            out.writeShort(c);
069        } else {
070            out.writeByte(super.getIndex());
071            out.writeByte(c);
072        }
073    }
074
075
076    private void setWide() {
077        wide = super.getIndex() > org.apache.bcel.Const.MAX_BYTE;
078        if (c > 0) {
079            wide = wide || (c > Byte.MAX_VALUE);
080        } else {
081            wide = wide || (c < Byte.MIN_VALUE);
082        }
083        if (wide) {
084            super.setLength(6); // wide byte included
085        } else {
086            super.setLength(3);
087        }
088    }
089
090
091    /**
092     * Read needed data (e.g. index) from file.
093     */
094    @Override
095    protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
096        this.wide = wide;
097        if (wide) {
098            super.setLength(6);
099            super.setIndexOnly(bytes.readUnsignedShort());
100            c = bytes.readShort();
101        } else {
102            super.setLength(3);
103            super.setIndexOnly(bytes.readUnsignedByte());
104            c = bytes.readByte();
105        }
106    }
107
108
109    /**
110     * @return mnemonic for instruction
111     */
112    @Override
113    public String toString( final boolean verbose ) {
114        return super.toString(verbose) + " " + c;
115    }
116
117
118    /**
119     * Set index of local variable.
120     */
121    @Override
122    public final void setIndex( final int n ) {
123        if (n < 0) {
124            throw new ClassGenException("Negative index value: " + n);
125        }
126        super.setIndexOnly(n);
127        setWide();
128    }
129
130
131    /**
132     * @return increment factor
133     */
134    public final int getIncrement() {
135        return c;
136    }
137
138
139    /**
140     * Set increment factor.
141     */
142    public final void setIncrement( final int c ) {
143        this.c = c;
144        setWide();
145    }
146
147
148    /** @return int type
149     */
150    @Override
151    public Type getType( final ConstantPoolGen cp ) {
152        return Type.INT;
153    }
154
155
156    /**
157     * Call corresponding visitor method(s). The order is:
158     * Call visitor methods of implemented interfaces first, then
159     * call methods according to the class hierarchy in descending order,
160     * i.e., the most specific visitXXX() call comes last.
161     *
162     * @param v Visitor object
163     */
164    @Override
165    public void accept( final Visitor v ) {
166        v.visitLocalVariableInstruction(this);
167        v.visitIINC(this);
168    }
169}