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    1   /*
    2    * Copyright  2000-2004 The Apache Software Foundation
    3    *
    4    *  Licensed under the Apache License, Version 2.0 (the "License");
    5    *  you may not use this file except in compliance with the License.
    6    *  You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   *  Unless required by applicable law or agreed to in writing, software
    11   *  distributed under the License is distributed on an "AS IS" BASIS,
    12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   *  See the License for the specific language governing permissions and
    14   *  limitations under the License.
    15   *
    16   */
    17  package org.apache.bcel.generic;
    18
    19  import java.io.DataOutputStream;
    20  import java.io.IOException;
    21
    22  /***
    23   * JSR - Jump to subroutine
    24   *
    25   * @version $Id: JSR.java 386056 2006-03-15 11:31:56Z tcurdt $
    26   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
    27   */
    28  public class JSR extends JsrInstruction implements VariableLengthInstruction {
    29
    30      /***
    31       * Empty constructor needed for the Class.newInstance() statement in
    32       * Instruction.readInstruction(). Not to be used otherwise.
    33       */
    34      JSR() {
    35      }
    36
    37
    38      public JSR(InstructionHandle target) {
    39          super(org.apache.bcel.Constants.JSR, target);
    40      }
    41
    42
    43      /***
    44       * Dump instruction as byte code to stream out.
    45       * @param out Output stream
    46       */
    47      public void dump( DataOutputStream out ) throws IOException {
    48          index = getTargetOffset();
    49          if (opcode == org.apache.bcel.Constants.JSR) {
    50              super.dump(out);
    51          } else { // JSR_W
    52              index = getTargetOffset();
    53              out.writeByte(opcode);
    54              out.writeInt(index);
    55          }
    56      }
    57
    58
    59      protected int updatePosition( int offset, int max_offset ) {
    60          int i = getTargetOffset(); // Depending on old position value
    61          position += offset; // Position may be shifted by preceding expansions
    62          if (Math.abs(i) >= (32767 - max_offset)) { // to large for short (estimate)
    63              opcode = org.apache.bcel.Constants.JSR_W;
    64              length = 5;
    65              return 2; // 5 - 3
    66          }
    67          return 0;
    68      }
    69
    70
    71      /***
    72       * Call corresponding visitor method(s). The order is:
    73       * Call visitor methods of implemented interfaces first, then
    74       * call methods according to the class hierarchy in descending order,
    75       * i.e., the most specific visitXXX() call comes last.
    76       *
    77       * @param v Visitor object
    78       */
    79      public void accept( Visitor v ) {
    80          v.visitStackProducer(this);
    81          v.visitVariableLengthInstruction(this);
    82          v.visitBranchInstruction(this);
    83          v.visitJsrInstruction(this);
    84          v.visitJSR(this);
    85      }
    86  }