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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.filter.codec.statemachine;
21  
22  import org.apache.mina.common.IoBuffer;
23  import org.apache.mina.filter.codec.ProtocolDecoderException;
24  import org.apache.mina.filter.codec.ProtocolDecoderOutput;
25  
26  /**
27   * @author The Apache MINA Project (dev@mina.apache.org)
28   * @version $Rev: 601994 $, $Date: 2007-12-06 21:58:00 -0700 (Thu, 06 Dec 2007) $
29   */
30  public abstract class IntegerDecodingState implements DecodingState {
31      
32      private int firstByte;
33      private int secondByte;
34      private int thirdByte;
35      private int counter;
36  
37      public IntegerDecodingState() {
38      }
39  
40      public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
41              throws Exception {
42          while (in.hasRemaining()) {
43              switch (counter) {
44              case 0:
45                  firstByte = in.getUnsigned();
46                  break;
47              case 1:
48                  secondByte = in.getUnsigned();
49                  break;
50              case 2:
51                  thirdByte = in.getUnsigned();
52                  break;
53              case 3:
54                  counter = 0;
55                  return finishDecode(
56                          (firstByte << 24) | (secondByte << 16) | (thirdByte << 8) | in.getUnsigned(),
57                          out);
58              default:
59                  throw new InternalError();
60              }
61              counter ++;
62          }
63  
64          return this;
65      }
66  
67      public DecodingState finishDecode(ProtocolDecoderOutput out)
68              throws Exception {
69          throw new ProtocolDecoderException(
70                  "Unexpected end of session while waiting for an integer.");
71      }
72  
73      protected abstract DecodingState finishDecode(int value,
74              ProtocolDecoderOutput out) throws Exception;
75  }