1
// Protocol Buffers - Google's data interchange format
2
// Copyright 2008 Google Inc. All rights reserved.
3
// http://code.google.com/p/protobuf/
5
// Redistribution and use in source and binary forms, with or without
6
// modification, are permitted provided that the following conditions are
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
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.
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.
31
// Author: kenton@google.com (Kenton Varda)
32
// atenasio@google.com (Chris Atenasio) (ZigZag transform)
33
// wink@google.com (Wink Saville) (refactored from wire_format.h)
34
// Based on original Protocol Buffers design by
35
// Sanjay Ghemawat, Jeff Dean, and others.
37
// This header is logically internal, but is made public because it is used
38
// from protocol-compiler-generated code, which may reside in other components.
40
#ifndef GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__
41
#define GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__
44
#include <google/protobuf/stubs/common.h>
45
#include <google/protobuf/message_lite.h>
46
#include <google/protobuf/io/coded_stream.h> // for CodedOutputStream::Varint32Size
51
template <typename T> class RepeatedField; // repeated_field.h
52
class UnknownFieldSet;
58
class StringPieceField;
60
// This class is for internal use by the protocol buffer library and by
61
// protocol-complier-generated message classes. It must not be called
62
// directly by clients.
64
// This class contains helpers for implementing the binary protocol buffer
65
// wire format without the need for reflection. Use WireFormat when using
68
// This class is really a namespace that contains only static methods.
69
class LIBPROTOBUF_EXPORT WireFormatLite {
72
// -----------------------------------------------------------------
73
// Helper constants and functions related to the format. These are
74
// mostly meant for internal and generated code to use.
76
// The wire format is composed of a sequence of tag/value pairs, each
77
// of which contains the value of one field (or one element of a repeated
78
// field). Each tag is encoded as a varint. The lower bits of the tag
79
// identify its wire type, which specifies the format of the data to follow.
80
// The rest of the bits contain the field number. Each type of field (as
81
// declared by FieldDescriptor::Type, in descriptor.h) maps to one of
82
// these wire types. Immediately following each tag is the field's value,
83
// encoded in the format specified by the wire type. Because the tag
84
// identifies the encoding of this data, it is possible to skip
85
// unrecognized fields for forwards compatibility.
90
WIRETYPE_LENGTH_DELIMITED = 2,
91
WIRETYPE_START_GROUP = 3,
92
WIRETYPE_END_GROUP = 4,
96
// Lite alternative to FieldDescriptor::Type. Must be kept in sync.
119
// Lite alternative to FieldDescriptor::CppType. Must be kept in sync.
130
CPPTYPE_MESSAGE = 10,
134
// Helper method to get the CppType for a particular Type.
135
static CppType FieldTypeToCppType(FieldType type);
137
// Given a FieldSescriptor::Type return its WireType
138
static inline WireFormatLite::WireType WireTypeForFieldType(
139
WireFormatLite::FieldType type) {
140
return kWireTypeForFieldType[type];
143
// Number of bits in a tag which identify the wire type.
144
static const int kTagTypeBits = 3;
145
// Mask for those bits.
146
static const uint32 kTagTypeMask = (1 << kTagTypeBits) - 1;
148
// Helper functions for encoding and decoding tags. (Inlined below and in
151
// This is different from MakeTag(field->number(), field->type()) in the case
152
// of packed repeated fields.
153
static uint32 MakeTag(int field_number, WireType type);
154
static WireType GetTagWireType(uint32 tag);
155
static int GetTagFieldNumber(uint32 tag);
157
// Compute the byte size of a tag. For groups, this includes both the start
159
static inline int TagSize(int field_number, WireFormatLite::FieldType type);
161
// -----------------------------------------------------------------
162
// Helpers for dealing with unknown fields
164
// Skips a field value with the given tag. The input should start
165
// positioned immediately after the tag. Skipped values are simply discarded,
166
// not recorded anywhere. See WireFormat::SkipField() for a version that
167
// records to an UnknownFieldSet.
168
static bool SkipField(io::CodedInputStream* input, uint32 tag,
169
UnknownFieldSet *unknown_fields);
171
// Reads and ignores a message from the input. If unknown_fields is non-NULL,
172
// the contents will be added to it.
173
static bool SkipMessage(io::CodedInputStream* input,
174
UnknownFieldSet* unknown_fields);
177
// Reads and ignores a message from the input. Skipped values may be stored
178
// in the UnknownFieldSet if it exists.
179
static bool SkipMessage(io::CodedInputStream* input);
181
// This macro does the same thing as WireFormatLite::MakeTag(), but the
182
// result is usable as a compile-time constant, which makes it usable
183
// as a switch case or a template input. WireFormatLite::MakeTag() is more
184
// type-safe, though, so prefer it if possible.
185
#define GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(FIELD_NUMBER, TYPE) \
186
static_cast<uint32>( \
187
((FIELD_NUMBER) << ::google::protobuf::internal::WireFormatLite::kTagTypeBits) \
190
// These are the tags for the old MessageSet format, which was defined as:
191
// message MessageSet {
192
// repeated group Item = 1 {
193
// required int32 type_id = 2;
194
// required string message = 3;
197
static const int kMessageSetItemNumber = 1;
198
static const int kMessageSetTypeIdNumber = 2;
199
static const int kMessageSetMessageNumber = 3;
200
static const int kMessageSetItemStartTag =
201
GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(kMessageSetItemNumber,
202
WireFormatLite::WIRETYPE_START_GROUP);
203
static const int kMessageSetItemEndTag =
204
GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(kMessageSetItemNumber,
205
WireFormatLite::WIRETYPE_END_GROUP);
206
static const int kMessageSetTypeIdTag =
207
GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(kMessageSetTypeIdNumber,
208
WireFormatLite::WIRETYPE_VARINT);
209
static const int kMessageSetMessageTag =
210
GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(kMessageSetMessageNumber,
211
WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
213
// Byte size of all tags of a MessageSet::Item combined.
214
static const int kMessageSetItemTagsSize;
216
// Helper functions for converting between floats/doubles and IEEE-754
217
// uint32s/uint64s so that they can be written. (Assumes your platform
218
// uses IEEE-754 floats.)
219
static uint32 EncodeFloat(float value);
220
static float DecodeFloat(uint32 value);
221
static uint64 EncodeDouble(double value);
222
static double DecodeDouble(uint64 value);
224
// Helper functions for mapping signed integers to unsigned integers in
225
// such a way that numbers with small magnitudes will encode to smaller
226
// varints. If you simply static_cast a negative number to an unsigned
227
// number and varint-encode it, it will always take 10 bytes, defeating
228
// the purpose of varint. So, for the "sint32" and "sint64" field types,
229
// we ZigZag-encode the values.
230
static uint32 ZigZagEncode32(int32 n);
231
static int32 ZigZagDecode32(uint32 n);
232
static uint64 ZigZagEncode64(int64 n);
233
static int64 ZigZagDecode64(uint64 n);
235
// Write the contents of an UnknownFieldSet to the output.
236
static void SerializeUnknownFields(const UnknownFieldSet& unknown_fields,
237
io::CodedOutputStream* output);
238
// Same as above, except writing directly to the provided buffer.
239
// Requires that the buffer have sufficient capacity for
240
// ComputeUnknownFieldsSize(unknown_fields).
242
// Returns a pointer past the last written byte.
243
static uint8* SerializeUnknownFieldsToArray(
244
const UnknownFieldSet& unknown_fields,
247
// Same thing except for messages that have the message_set_wire_format
249
static void SerializeUnknownMessageSetItems(
250
const UnknownFieldSet& unknown_fields,
251
io::CodedOutputStream* output);
252
// Same as above, except writing directly to the provided buffer.
253
// Requires that the buffer have sufficient capacity for
254
// ComputeUnknownMessageSetItemsSize(unknown_fields).
256
// Returns a pointer past the last written byte.
257
static uint8* SerializeUnknownMessageSetItemsToArray(
258
const UnknownFieldSet& unknown_fields,
261
// Compute the size of the UnknownFieldSet on the wire.
262
static int ComputeUnknownFieldsSize(const UnknownFieldSet& unknown_fields);
264
// Same thing except for messages that have the message_set_wire_format
266
static int ComputeUnknownMessageSetItemsSize(
267
const UnknownFieldSet& unknown_fields);
269
// =================================================================
270
// Methods for reading/writing individual field. The implementations
271
// of these methods are defined in wire_format_lite_inl.h; you must #include
272
// that file to use these.
274
// Avoid ugly line wrapping
275
#define input io::CodedInputStream* input
276
#define output io::CodedOutputStream* output
277
#define field_number int field_number
278
#define INL GOOGLE_ATTRIBUTE_ALWAYS_INLINE
280
// Read fields, not including tags. The assumption is that you already
281
// read the tag to determine what field to read.
283
// For primitive fields, we just use a templatized routine parameterized by
284
// the represented type and the FieldType. These are specialized with the
285
// appropriate definition for each declared type.
286
template <typename CType, enum FieldType DeclaredType>
287
static inline bool ReadPrimitive(input, CType* value) INL;
289
// Reads repeated primitive values, with optimizations for repeats.
290
// tag_size and tag should both be compile-time constants provided by the
291
// protocol compiler.
292
template <typename CType, enum FieldType DeclaredType>
293
static inline bool ReadRepeatedPrimitive(int tag_size,
296
RepeatedField<CType>* value) INL;
298
// Identical to ReadRepeatedPrimitive, except will not inline the
300
template <typename CType, enum FieldType DeclaredType>
301
static bool ReadRepeatedPrimitiveNoInline(int tag_size,
304
RepeatedField<CType>* value);
306
// Reads a primitive value directly from the provided buffer. It returns a
307
// pointer past the segment of data that was read.
309
// This is only implemented for the types with fixed wire size, e.g.
310
// float, double, and the (s)fixed* types.
311
template <typename CType, enum FieldType DeclaredType>
312
static inline const uint8* ReadPrimitiveFromArray(const uint8* buffer,
315
// Reads a primitive packed field.
317
// This is only implemented for packable types.
318
template <typename CType, enum FieldType DeclaredType>
319
static inline bool ReadPackedPrimitive(input,
320
RepeatedField<CType>* value) INL;
322
// Identical to ReadPackedPrimitive, except will not inline the
324
template <typename CType, enum FieldType DeclaredType>
325
static bool ReadPackedPrimitiveNoInline(input, RepeatedField<CType>* value);
327
// Read a packed enum field. Values for which is_valid() returns false are
329
static bool ReadPackedEnumNoInline(input,
330
bool (*is_valid)(int),
331
RepeatedField<int>* value);
333
static bool ReadString(input, string* value);
334
static bool ReadBytes (input, string* value);
336
static inline bool ReadGroup (field_number, input, MessageLite* value);
337
static inline bool ReadMessage(input, MessageLite* value);
339
// Like above, but de-virtualize the call to MergePartialFromCodedStream().
340
// The pointer must point at an instance of MessageType, *not* a subclass (or
341
// the subclass must not override MergePartialFromCodedStream()).
342
template<typename MessageType>
343
static inline bool ReadGroupNoVirtual(field_number, input,
345
template<typename MessageType>
346
static inline bool ReadMessageNoVirtual(input, MessageType* value);
348
// Write a tag. The Write*() functions typically include the tag, so
349
// normally there's no need to call this unless using the Write*NoTag()
351
static inline void WriteTag(field_number, WireType type, output) INL;
353
// Write fields, without tags.
354
static inline void WriteInt32NoTag (int32 value, output) INL;
355
static inline void WriteInt64NoTag (int64 value, output) INL;
356
static inline void WriteUInt32NoTag (uint32 value, output) INL;
357
static inline void WriteUInt64NoTag (uint64 value, output) INL;
358
static inline void WriteSInt32NoTag (int32 value, output) INL;
359
static inline void WriteSInt64NoTag (int64 value, output) INL;
360
static inline void WriteFixed32NoTag (uint32 value, output) INL;
361
static inline void WriteFixed64NoTag (uint64 value, output) INL;
362
static inline void WriteSFixed32NoTag(int32 value, output) INL;
363
static inline void WriteSFixed64NoTag(int64 value, output) INL;
364
static inline void WriteFloatNoTag (float value, output) INL;
365
static inline void WriteDoubleNoTag (double value, output) INL;
366
static inline void WriteBoolNoTag (bool value, output) INL;
367
static inline void WriteEnumNoTag (int value, output) INL;
369
// Write fields, including tags.
370
static void WriteInt32 (field_number, int32 value, output);
371
static void WriteInt64 (field_number, int64 value, output);
372
static void WriteUInt32 (field_number, uint32 value, output);
373
static void WriteUInt64 (field_number, uint64 value, output);
374
static void WriteSInt32 (field_number, int32 value, output);
375
static void WriteSInt64 (field_number, int64 value, output);
376
static void WriteFixed32 (field_number, uint32 value, output);
377
static void WriteFixed64 (field_number, uint64 value, output);
378
static void WriteSFixed32(field_number, int32 value, output);
379
static void WriteSFixed64(field_number, int64 value, output);
380
static void WriteFloat (field_number, float value, output);
381
static void WriteDouble (field_number, double value, output);
382
static void WriteBool (field_number, bool value, output);
383
static void WriteEnum (field_number, int value, output);
385
static void WriteString(field_number, const string& value, output);
386
static void WriteBytes (field_number, const string& value, output);
388
static void WriteGroup(
389
field_number, const MessageLite& value, output);
390
static void WriteMessage(
391
field_number, const MessageLite& value, output);
392
// Like above, but these will check if the output stream has enough
393
// space to write directly to a flat array.
394
static void WriteGroupMaybeToArray(
395
field_number, const MessageLite& value, output);
396
static void WriteMessageMaybeToArray(
397
field_number, const MessageLite& value, output);
399
// Like above, but de-virtualize the call to SerializeWithCachedSizes(). The
400
// pointer must point at an instance of MessageType, *not* a subclass (or
401
// the subclass must not override SerializeWithCachedSizes()).
402
template<typename MessageType>
403
static inline void WriteGroupNoVirtual(
404
field_number, const MessageType& value, output);
405
template<typename MessageType>
406
static inline void WriteMessageNoVirtual(
407
field_number, const MessageType& value, output);
410
#define output uint8* target
412
// Like above, but use only *ToArray methods of CodedOutputStream.
413
static inline uint8* WriteTagToArray(field_number, WireType type, output) INL;
415
// Write fields, without tags.
416
static inline uint8* WriteInt32NoTagToArray (int32 value, output) INL;
417
static inline uint8* WriteInt64NoTagToArray (int64 value, output) INL;
418
static inline uint8* WriteUInt32NoTagToArray (uint32 value, output) INL;
419
static inline uint8* WriteUInt64NoTagToArray (uint64 value, output) INL;
420
static inline uint8* WriteSInt32NoTagToArray (int32 value, output) INL;
421
static inline uint8* WriteSInt64NoTagToArray (int64 value, output) INL;
422
static inline uint8* WriteFixed32NoTagToArray (uint32 value, output) INL;
423
static inline uint8* WriteFixed64NoTagToArray (uint64 value, output) INL;
424
static inline uint8* WriteSFixed32NoTagToArray(int32 value, output) INL;
425
static inline uint8* WriteSFixed64NoTagToArray(int64 value, output) INL;
426
static inline uint8* WriteFloatNoTagToArray (float value, output) INL;
427
static inline uint8* WriteDoubleNoTagToArray (double value, output) INL;
428
static inline uint8* WriteBoolNoTagToArray (bool value, output) INL;
429
static inline uint8* WriteEnumNoTagToArray (int value, output) INL;
431
// Write fields, including tags.
432
static inline uint8* WriteInt32ToArray(
433
field_number, int32 value, output) INL;
434
static inline uint8* WriteInt64ToArray(
435
field_number, int64 value, output) INL;
436
static inline uint8* WriteUInt32ToArray(
437
field_number, uint32 value, output) INL;
438
static inline uint8* WriteUInt64ToArray(
439
field_number, uint64 value, output) INL;
440
static inline uint8* WriteSInt32ToArray(
441
field_number, int32 value, output) INL;
442
static inline uint8* WriteSInt64ToArray(
443
field_number, int64 value, output) INL;
444
static inline uint8* WriteFixed32ToArray(
445
field_number, uint32 value, output) INL;
446
static inline uint8* WriteFixed64ToArray(
447
field_number, uint64 value, output) INL;
448
static inline uint8* WriteSFixed32ToArray(
449
field_number, int32 value, output) INL;
450
static inline uint8* WriteSFixed64ToArray(
451
field_number, int64 value, output) INL;
452
static inline uint8* WriteFloatToArray(
453
field_number, float value, output) INL;
454
static inline uint8* WriteDoubleToArray(
455
field_number, double value, output) INL;
456
static inline uint8* WriteBoolToArray(
457
field_number, bool value, output) INL;
458
static inline uint8* WriteEnumToArray(
459
field_number, int value, output) INL;
461
static inline uint8* WriteStringToArray(
462
field_number, const string& value, output) INL;
463
static inline uint8* WriteBytesToArray(
464
field_number, const string& value, output) INL;
466
static inline uint8* WriteGroupToArray(
467
field_number, const MessageLite& value, output) INL;
468
static inline uint8* WriteMessageToArray(
469
field_number, const MessageLite& value, output) INL;
471
// Like above, but de-virtualize the call to SerializeWithCachedSizes(). The
472
// pointer must point at an instance of MessageType, *not* a subclass (or
473
// the subclass must not override SerializeWithCachedSizes()).
474
template<typename MessageType>
475
static inline uint8* WriteGroupNoVirtualToArray(
476
field_number, const MessageType& value, output) INL;
477
template<typename MessageType>
478
static inline uint8* WriteMessageNoVirtualToArray(
479
field_number, const MessageType& value, output) INL;
487
// Compute the byte size of a field. The XxSize() functions do NOT include
488
// the tag, so you must also call TagSize(). (This is because, for repeated
489
// fields, you should only call TagSize() once and multiply it by the element
490
// count, but you may have to call XxSize() for each individual element.)
491
static inline int Int32Size ( int32 value);
492
static inline int Int64Size ( int64 value);
493
static inline int UInt32Size (uint32 value);
494
static inline int UInt64Size (uint64 value);
495
static inline int SInt32Size ( int32 value);
496
static inline int SInt64Size ( int64 value);
497
static inline int EnumSize ( int value);
499
// These types always have the same size.
500
static const int kFixed32Size = 4;
501
static const int kFixed64Size = 8;
502
static const int kSFixed32Size = 4;
503
static const int kSFixed64Size = 8;
504
static const int kFloatSize = 4;
505
static const int kDoubleSize = 8;
506
static const int kBoolSize = 1;
508
static inline int StringSize(const string& value);
509
static inline int BytesSize (const string& value);
511
static inline int GroupSize (const MessageLite& value);
512
static inline int MessageSize(const MessageLite& value);
514
// Like above, but de-virtualize the call to ByteSize(). The
515
// pointer must point at an instance of MessageType, *not* a subclass (or
516
// the subclass must not override ByteSize()).
517
template<typename MessageType>
518
static inline int GroupSizeNoVirtual (const MessageType& value);
519
template<typename MessageType>
520
static inline int MessageSizeNoVirtual(const MessageType& value);
522
// Given the length of data, calculate the byte size of the data on the
523
// wire if we encode the data as a length delimited field.
524
static inline int LengthDelimitedSize(int length);
527
// A helper method for the repeated primitive reader. This method has
528
// optimizations for primitive types that have fixed size on the wire, and
529
// can be read using potentially faster paths.
530
template <typename CType, enum FieldType DeclaredType>
531
static inline bool ReadRepeatedFixedSizePrimitive(
534
google::protobuf::io::CodedInputStream* input,
535
RepeatedField<CType>* value) GOOGLE_ATTRIBUTE_ALWAYS_INLINE;
537
static const CppType kFieldTypeToCppTypeMap[];
538
static const WireFormatLite::WireType kWireTypeForFieldType[];
540
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(WireFormatLite);
543
// A class which deals with unknown values by saving them to an UnknownFieldSet.
544
class LIBPROTOBUF_EXPORT FieldSkipper {
546
FieldSkipper(UnknownFieldSet* unknown_fields)
547
: unknown_fields_(unknown_fields) {}
549
// Skip a field whose tag has already been consumed.
550
bool SkipField(io::CodedInputStream* input, uint32 tag);
552
// Skip an entire message or group, up to an end-group tag (which is consumed)
554
bool SkipMessage(io::CodedInputStream* input);
556
// Deal with an already-parsed unrecognized enum value. The default
557
// implementation does nothing, but the UnknownFieldSet-based implementation
558
// saves it as an unknown varint.
559
void SkipUnknownEnum(int field_number, int value);
562
UnknownFieldSet* unknown_fields_;
565
// inline methods ====================================================
567
inline WireFormatLite::CppType
568
WireFormatLite::FieldTypeToCppType(FieldType type) {
569
return kFieldTypeToCppTypeMap[type];
572
inline uint32 WireFormatLite::MakeTag(int field_number, WireType type) {
573
return GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(field_number, type);
576
inline WireFormatLite::WireType WireFormatLite::GetTagWireType(uint32 tag) {
577
return static_cast<WireType>(tag & kTagTypeMask);
580
inline int WireFormatLite::GetTagFieldNumber(uint32 tag) {
581
return static_cast<int>(tag >> kTagTypeBits);
584
inline int WireFormatLite::TagSize(int field_number,
585
WireFormatLite::FieldType type) {
586
int result = io::CodedOutputStream::VarintSize32(
587
field_number << kTagTypeBits);
588
if (type == TYPE_GROUP) {
589
// Groups have both a start and an end tag.
596
inline uint32 WireFormatLite::EncodeFloat(float value) {
597
union {float f; uint32 i;};
602
inline float WireFormatLite::DecodeFloat(uint32 value) {
603
union {float f; uint32 i;};
608
inline uint64 WireFormatLite::EncodeDouble(double value) {
609
union {double f; uint64 i;};
614
inline double WireFormatLite::DecodeDouble(uint64 value) {
615
union {double f; uint64 i;};
620
// ZigZag Transform: Encodes signed integers so that they can be
621
// effectively used with varint encoding.
623
// varint operates on unsigned integers, encoding smaller numbers into
624
// fewer bytes. If you try to use it on a signed integer, it will treat
625
// this number as a very large unsigned integer, which means that even
626
// small signed numbers like -1 will take the maximum number of bytes
627
// (10) to encode. ZigZagEncode() maps signed integers to unsigned
628
// in such a way that those with a small absolute value will have smaller
629
// encoded values, making them appropriate for encoding using varint.
632
// -------------------------
638
// 2147483647 -> 4294967294
639
// -2147483648 -> 4294967295
644
inline uint32 WireFormatLite::ZigZagEncode32(int32 n) {
645
// Note: the right-shift must be arithmetic
646
return (n << 1) ^ (n >> 31);
649
inline int32 WireFormatLite::ZigZagDecode32(uint32 n) {
650
return (n >> 1) ^ -static_cast<int32>(n & 1);
653
inline uint64 WireFormatLite::ZigZagEncode64(int64 n) {
654
// Note: the right-shift must be arithmetic
655
return (n << 1) ^ (n >> 63);
658
inline int64 WireFormatLite::ZigZagDecode64(uint64 n) {
659
return (n >> 1) ^ -static_cast<int64>(n & 1);
662
} // namespace internal
663
} // namespace protobuf
665
} // namespace google
666
#endif // GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__