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    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   * RET - Return from subroutine
    61   *
    62   * <PRE>Stack: ..., -> ..., address</PRE>
    63   *
    64   * @version $Id: RET.java,v 1.1.1.1 2001/10/29 20:00:25 jvanzyl Exp $
    65   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
    66   */
    67  public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
    68    private boolean wide;
    69    private int     index; // index to local variable containg the return address
    70
    71    /***
    72     * Empty constructor needed for the Class.newInstance() statement in
    73     * Instruction.readInstruction(). Not to be used otherwise.
    74     */
    75    RET() {}
    76
    77    public RET(int index) {
    78      super(org.apache.bcel.Constants.RET, (short)2);
    79      setIndex(index);   // May set wide as side effect
    80    }
    81
    82    /***
    83     * Dump instruction as byte code to stream out.
    84     * @param out Output stream
    85     */
    86    public void dump(DataOutputStream out) throws IOException {
    87      if(wide)
    88        out.writeByte(org.apache.bcel.Constants.WIDE);
    89
    90      out.writeByte(opcode);
    91
    92      if(wide)
    93        out.writeShort(index);
    94      else
    95        out.writeByte(index);
    96    }
    97
    98    private final void setWide() {
    99      if(wide = index > org.apache.bcel.Constants.MAX_BYTE)
    100       length = 4; // Including the wide byte
    101     else
    102       length = 2;
    103   }
    104
    105   /***
    106    * Read needed data (e.g. index) from file.
    107    */
    108   protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
    109   {
    110     this.wide = wide;
    111
    112     if(wide) {
    113       index  = bytes.readUnsignedShort();
    114       length = 4;
    115     } else {
    116       index = bytes.readUnsignedByte();
    117       length = 2;
    118     }
    119   }
    120
    121   /***
    122    * @return index of local variable containg the return address
    123    */
    124   public final int getIndex() { return index; }
    125
    126   /***
    127    * Set index of local variable containg the return address
    128    */
    129   public final void setIndex(int n) {
    130     if(n < 0)
    131       throw new ClassGenException("Negative index value: " + n);
    132
    133     index = n;
    134     setWide();
    135   }
    136
    137   /***
    138    * @return mnemonic for instruction
    139    */
    140   public String toString(boolean verbose) {
    141     return super.toString(verbose) + " " + index;
    142   }
    143
    144   /*** @return return address type
    145    */
    146   public Type getType(ConstantPoolGen cp) {
    147       return ReturnaddressType.NO_TARGET;
    148   }
    149
    150   /***
    151    * Call corresponding visitor method(s). The order is:
    152    * Call visitor methods of implemented interfaces first, then
    153    * call methods according to the class hierarchy in descending order,
    154    * i.e., the most specific visitXXX() call comes last.
    155    *
    156    * @param v Visitor object
    157    */
    158   public void accept(Visitor v) {
    159     v.visitRET(this);
    160   }
    161 }

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