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.core.buffer.IoBuffer;
23 import org.apache.mina.filter.codec.ProtocolDecoderException;
24 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
25
26 /**
27 * {@link DecodingState} which decodes <code>short</code> values in big-endian
28 * order (high bytes come first).
29 *
30 * @author The Apache MINA Project (dev@mina.apache.org)
31 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (jeu, 26 jun 2008) $
32 */
33 public abstract class ShortIntegerDecodingState implements DecodingState {
34
35 private int highByte;
36 private int counter;
37
38 /**
39 * {@inheritDoc}
40 */
41 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
42 throws Exception {
43
44 while (in.hasRemaining()) {
45 switch (counter) {
46 case 0:
47 highByte = in.getUnsigned();
48 break;
49 case 1:
50 counter = 0;
51 return finishDecode((short) ((highByte << 8) | in.getUnsigned()), out);
52 default:
53 throw new InternalError();
54 }
55
56 counter ++;
57 }
58 return this;
59 }
60
61 /**
62 * {@inheritDoc}
63 */
64 public DecodingState finishDecode(ProtocolDecoderOutput out)
65 throws Exception {
66 throw new ProtocolDecoderException(
67 "Unexpected end of session while waiting for a short integer.");
68 }
69
70 /**
71 * Invoked when this state has consumed a complete <code>short</code>.
72 *
73 * @param value the short.
74 * @param out the current {@link ProtocolDecoderOutput} used to write
75 * decoded messages.
76 * @return the next state if a state transition was triggered (use
77 * <code>this</code> for loop transitions) or <code>null</code> if
78 * the state machine has reached its end.
79 * @throws Exception if the read data violated protocol specification.
80 */
81 protected abstract DecodingState finishDecode(short value,
82 ProtocolDecoderOutput out) throws Exception;
83 }