1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc.  All rights reserved.
3// http://code.google.com/p/protobuf/
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions are
7// met:
8//
9//     * Redistributions of source code must retain the above copyright
10// notice, this list of conditions and the following disclaimer.
11//     * Redistributions in binary form must reproduce the above
12// copyright notice, this list of conditions and the following disclaimer
13// in the documentation and/or other materials provided with the
14// distribution.
15//     * Neither the name of Google Inc. nor the names of its
16// contributors may be used to endorse or promote products derived from
17// this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31package com.google.protobuf.micro;
32
33/**
34 * This class is used internally by the Protocol Buffer library and generated
35 * message implementations.  It is public only because those generated messages
36 * do not reside in the {@code protobuf} package.  Others should not use this
37 * class directly.
38 *
39 * This class contains constants and helper functions useful for dealing with
40 * the Protocol Buffer wire format.
41 *
42 * @author kenton@google.com Kenton Varda
43 */
44public final class WireFormatMicro {
45  // Do not allow instantiation.
46  private WireFormatMicro() {}
47
48  static final int WIRETYPE_VARINT           = 0;
49  static final int WIRETYPE_FIXED64          = 1;
50  static final int WIRETYPE_LENGTH_DELIMITED = 2;
51  static final int WIRETYPE_START_GROUP      = 3;
52  static final int WIRETYPE_END_GROUP        = 4;
53  static final int WIRETYPE_FIXED32          = 5;
54
55  static final int TAG_TYPE_BITS = 3;
56  static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1;
57
58  /** Given a tag value, determines the wire type (the lower 3 bits). */
59  static int getTagWireType(final int tag) {
60    return tag & TAG_TYPE_MASK;
61  }
62
63  /** Given a tag value, determines the field number (the upper 29 bits). */
64  public static int getTagFieldNumber(final int tag) {
65    return tag >>> TAG_TYPE_BITS;
66  }
67
68  /** Makes a tag value given a field number and wire type. */
69  static int makeTag(final int fieldNumber, final int wireType) {
70    return (fieldNumber << TAG_TYPE_BITS) | wireType;
71  }
72
73  // Field numbers for feilds in MessageSet wire format.
74  static final int MESSAGE_SET_ITEM    = 1;
75  static final int MESSAGE_SET_TYPE_ID = 2;
76  static final int MESSAGE_SET_MESSAGE = 3;
77
78  // Tag numbers.
79  static final int MESSAGE_SET_ITEM_TAG =
80    makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP);
81  static final int MESSAGE_SET_ITEM_END_TAG =
82    makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP);
83  static final int MESSAGE_SET_TYPE_ID_TAG =
84    makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT);
85  static final int MESSAGE_SET_MESSAGE_TAG =
86    makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED);
87}
88