View Javadoc

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  }