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1   /*
2    * @(#) RET.java Jan 8, 2004
3    * 
4    * Copyright (c) 2003 Delft University of Technology Jaffalaan 5, 2628 BX Delft,
5    * the Netherlands All rights reserved.
6    * 
7    * This software is proprietary information of Delft University of Technology
8    * The code is published under the General Public License
9    */
10  package nl.tudelft.simulation.dsol.interpreter.operations;
11  
12  import java.io.DataInput;
13  import java.io.IOException;
14  
15  import nl.tudelft.simulation.dsol.interpreter.LocalVariable;
16  import nl.tudelft.simulation.dsol.interpreter.OperandStack;
17  import nl.tudelft.simulation.dsol.interpreter.classfile.Constant;
18  import nl.tudelft.simulation.language.primitives.Primitive;
19  
20  /***
21   * The RET operation as defined in <a
22   * href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/Instructions2.doc12.html">
23   * http://java.sun.com/docs/books/vmspec/2nd-edition/html/Instructions2.doc12.html
24   * </a>.
25   * <p>
26   * (c) copyright 2003 <a href="http://www.simulation.tudelft.nl">Delft
27   * University of Technology </a>, the Netherlands. <br>
28   * See for project information <a
29   * href="http://www.simulation.tudelft.nl">www.simulation.tudelft.nl </a> <br>
30   * License of use: <a href="http://www.gnu.org/copyleft/gpl.html">General Public
31   * License (GPL) </a>, no warranty <br>
32   * 
33   * @author <a href="http://www.tbm.tudelft.nl/webstaf/peterja/index.htm">Peter
34   *         Jacobs </a><a
35   *         href="http://www.tbm.tudelft.nl/webstaf/alexandv/index.htm">Alexander
36   *         Verbraeck </a>
37   * @version 1.3 Apr 6, 2004
38   * @since 1.4
39   */
40  public class RET extends JumpOperation
41  {
42  	/*** OP refers to the operand code */
43  	public static final int OP = 169;
44  
45  	/*** the index to use */
46  	private int index = -1;
47  
48  	/*** see the wide statement */
49  	private boolean widened = false;
50  
51  	/***
52  	 * constructs a new RET
53  	 * 
54  	 * @param dataInput the dataInput to read
55  	 * @throws IOException on IOException
56  	 */
57  	public RET(final DataInput dataInput) throws IOException
58  	{
59  		this(dataInput, false);
60  	}
61  
62  	/***
63  	 * constructs a new RET
64  	 * 
65  	 * @param dataInput the dataInput to read
66  	 * @param widened whether or not to widen
67  	 * @throws IOException on IOException
68  	 */
69  	public RET(final DataInput dataInput, final boolean widened)
70  			throws IOException
71  	{
72  		super();
73  		this.widened = widened;
74  		if (widened)
75  		{
76  			this.index = dataInput.readUnsignedShort();
77  		} else
78  		{
79  			this.index = dataInput.readUnsignedByte();
80  		}
81  	}
82  
83  	/***
84  	 * @see nl.tudelft.simulation.dsol.interpreter.operations.JumpOperation
85  	 *      #execute(nl.tudelft.simulation.dsol.interpreter.OperandStack,
86  	 *      nl.tudelft.simulation.dsol.interpreter.classfile.Constant[],
87  	 *      nl.tudelft.simulation.dsol.interpreter.LocalVariable[])
88  	 */
89  	public int execute(final OperandStack stack, final Constant[] constantPool,
90  			final LocalVariable[] localVariables)
91  	{
92  		return Primitive.toInteger(localVariables[this.index].getValue())
93  				.intValue();
94  	}
95  
96  	/***
97  	 * @see nl.tudelft.simulation.dsol.interpreter.Operation#getByteLength()
98  	 */
99  	public int getByteLength()
100 	{
101 		int result = OPCODE_BYTE_LENGTH + 1;
102 		if (this.widened)
103 		{
104 			result++;
105 		}
106 		return result;
107 	}
108 
109 	/***
110 	 * @see nl.tudelft.simulation.dsol.interpreter.Operation#getOpcode()
111 	 */
112 	public int getOpcode()
113 	{
114 		return RET.OP;
115 	}
116 }