1   package org.apache.bcel.generic;
2   
3   /* ====================================================================
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution,
22   *    if any, must include the following acknowledgment:
23   *       "This product includes software developed by the
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowledgment may appear in the software itself,
26   *    if and wherever such third-party acknowledgments normally appear.
27   *
28   * 4. The names "Apache" and "Apache Software Foundation" and
29   *    "Apache BCEL" must not be used to endorse or promote products
30   *    derived from this software without prior written permission. For
31   *    written permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache",
34   *    "Apache BCEL", nor may "Apache" appear in their name, without
35   *    prior written permission of the Apache Software Foundation.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
53   * information on the Apache Software Foundation, please see
54   * <http://www.apache.org/>.
55   */
56  import java.io.*;
57  import org.apache.bcel.util.ByteSequence;
58  
59  /***
60   * IINC - Increment local variable by constant
61   *
62   * @version $Id: IINC.java,v 1.2 2002/03/12 09:24:01 mdahm Exp $
63   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
64   */
65  public class IINC extends LocalVariableInstruction {
66    private boolean wide;
67    private int     c;
68  
69    /***
70     * Empty constructor needed for the Class.newInstance() statement in
71     * Instruction.readInstruction(). Not to be used otherwise.
72     */
73    IINC() {}
74  
75    /***
76     * @param n index of local variable
77     * @param c increment factor
78     */
79    public IINC(int n, int c) {
80      super(); // Default behaviour of LocalVariableInstruction causes error
81  
82      this.opcode = org.apache.bcel.Constants.IINC;
83      this.length = (short)3;
84  
85      setIndex(n);    // May set wide as side effect
86      setIncrement(c);
87    }
88  
89    /***
90     * Dump instruction as byte code to stream out.
91     * @param out Output stream
92     */
93    public void dump(DataOutputStream out) throws IOException {
94      if(wide) // Need WIDE prefix ?
95        out.writeByte(org.apache.bcel.Constants.WIDE);
96  
97      out.writeByte(opcode);
98  
99      if(wide) {
100       out.writeShort(n);
101       out.writeShort(c);
102     } else {
103       out.writeByte(n);
104       out.writeByte(c);
105     }
106   }
107 
108   private final void setWide() {
109     if(wide = ((n > org.apache.bcel.Constants.MAX_SHORT) ||
110 	       (Math.abs(c) > Byte.MAX_VALUE)))
111       length = 6; // wide byte included  
112     else
113       length = 3;
114   }
115 
116   /***
117    * Read needed data (e.g. index) from file.
118    */
119   protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
120   {
121     this.wide = wide;
122 
123     if(wide) {
124       length = 6;
125       n = bytes.readUnsignedShort();
126       c = bytes.readShort();
127     } else {
128       length = 3;
129       n = bytes.readUnsignedByte();
130       c = bytes.readByte();
131     }
132   }
133 
134   /***
135    * @return mnemonic for instruction
136    */
137   public String toString(boolean verbose) {
138     return super.toString(verbose) + " " + c;
139   }  
140 
141   /***
142    * Set index of local variable.
143    */
144   public final void setIndex(int n) { 
145     if(n < 0)
146       throw new ClassGenException("Negative index value: " + n);
147 
148     this.n = n;
149     setWide();
150   }
151 
152   /***
153    * @return increment factor
154    */
155   public final int getIncrement() { return c; }
156 
157   /***
158    * Set increment factor.
159    */
160   public final void setIncrement(int c) {
161     this.c = c;
162     setWide();
163   }
164 
165   /*** @return int type
166    */
167   public Type getType(ConstantPoolGen cp) {
168     return Type.INT;
169   }
170 
171   /***
172    * Call corresponding visitor method(s). The order is:
173    * Call visitor methods of implemented interfaces first, then
174    * call methods according to the class hierarchy in descending order,
175    * i.e., the most specific visitXXX() call comes last.
176    *
177    * @param v Visitor object
178    */
179   public void accept(Visitor v) {
180     v.visitLocalVariableInstruction(this);
181     v.visitIINC(this);
182   }
183 }
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