1 /*
 2  * Copyright (c) 2009, 2019, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 package org.openjdk.asmtools.jdec;
24 
25 import java.io.ByteArrayInputStream;
26 import java.util.Stack;
27 
28 /**
29  * this class provides functionality needed to read class files:
30  * <ul>
31  * <li>methods to read unsigned integers of various length
32  * <li>counts bytes read so far
33  * </ul>
34  */
35 public class NestedByteArrayInputStream extends ByteArrayInputStream {
36 
37     NestedByteArrayInputStream(byte buf[]) {
38         super(buf);
39     }
40 
41     NestedByteArrayInputStream(byte buf[], int offset, int length) {
42         super(buf, offset, length);
43     }
44 
45     public int getPos() {
46         return pos;
47     }
48     Stack savedStates = new Stack();
49 
50     public void enter(int range) {
51         savedStates.push(count);
52         if (pos + range < count) {
53             count = pos + range;
54         }
55     }
56 
57     public void leave() {
58         pos = count;
59         count = ((Integer) savedStates.pop()).intValue();
60     }
61 } // end class NestedByteArrayInputStream
62