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1 //
2 // Copyright (C) 2005 United States Government as represented by the
3 // Administrator of the National Aeronautics and Space Administration
4 // (NASA). All Rights Reserved.
5 //
6 // This software is distributed under the NASA Open Source Agreement
7 // (NOSA), version 1.3. The NOSA has been approved by the Open Source
8 // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
9 // directory tree for the complete NOSA document.
10 //
11 // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12 // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13 // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14 // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15 // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16 // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17 // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18 //
19 import gov.nasa.jpf.jvm.Verify;
20
21
22 /**
23  * DOCUMENT ME!
24  */
25 class lockExample {
26   public static int LOCK = 0;
27
28   public static void lock () {
29     assert (LOCK == 0);
30     LOCK = 1;
31   }
32
33   public static void main (String JavaDoc[] args) {
34     int got_lock = 0;
35
36     do {
37       if (Verify.randomBool()) {
38         lock();
39         got_lock++;
40       }
41
42       if (got_lock != 0) {
43         unlock();
44       }
45
46       got_lock--;
47     } while (Verify.randomBool());
48   }
49
50   public static void unlock () {
51     assert (LOCK == 1);
52     LOCK = 0;
53   }
54 }
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