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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 
31 package 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  */
44 public final class WireFormatMicro {
45   // Do not allow instantiation.
WireFormatMicro()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). */
getTagWireType(final int tag)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). */
getTagFieldNumber(final int tag)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. */
makeTag(final int fieldNumber, final int wireType)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