1 /* Copyright 2015 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 #ifndef TENSORFLOW_CORE_LIB_IO_PROTO_ENCODE_HELPER_H_ 17 #define TENSORFLOW_CORE_LIB_IO_PROTO_ENCODE_HELPER_H_ 18 19 #include "tensorflow/core/lib/core/coding.h" 20 #include "tensorflow/core/lib/core/stringpiece.h" 21 #include "tensorflow/core/platform/protobuf.h" 22 23 // A helper class for appending various kinds of values in protocol 24 // buffer encoding format to a buffer. The client gives a pointer to 25 // a buffer and a maximum size guarantee for the number of bytes they 26 // will add to this buffer. 27 namespace tensorflow { 28 namespace io { 29 30 class ProtoEncodeHelper { 31 public: ProtoEncodeHelper(char * buf,int max_size)32 ProtoEncodeHelper(char* buf, int max_size) 33 : base_(buf), p_(buf), limit_(base_ + max_size) {} 34 ~ProtoEncodeHelper()35 ~ProtoEncodeHelper() { 36 // Make sure callers didn't do operations that went over max_size promised 37 DCHECK_LE(p_, limit_); 38 } 39 data()40 const char* data() const { return base_; } size()41 size_t size() const { return p_ - base_; } 42 WriteUint64(int tag,uint64 v)43 void WriteUint64(int tag, uint64 v) { 44 Encode32(combine(tag, WIRETYPE_VARINT)); 45 Encode64(v); 46 } WriteBool(int tag,bool v)47 void WriteBool(int tag, bool v) { 48 Encode32(combine(tag, WIRETYPE_VARINT)); 49 EncodeBool(v); 50 } WriteString(int tag,StringPiece v)51 void WriteString(int tag, StringPiece v) { 52 Encode32(combine(tag, WIRETYPE_LENGTH_DELIMITED)); 53 Encode32(v.size()); 54 EncodeBytes(v.data(), v.size()); 55 } WriteVarlengthBeginning(int tag,uint32 len)56 void WriteVarlengthBeginning(int tag, uint32 len) { 57 Encode32(combine(tag, WIRETYPE_LENGTH_DELIMITED)); 58 Encode32(len); 59 } WriteRawBytes(StringPiece v)60 void WriteRawBytes(StringPiece v) { EncodeBytes(v.data(), v.size()); } 61 62 private: 63 // Note: this module's behavior must match the protocol buffer wire encoding 64 // format. 65 enum { 66 WIRETYPE_VARINT = 0, 67 WIRETYPE_LENGTH_DELIMITED = 2, 68 }; combine(uint32 tag,uint32 type)69 static uint32 combine(uint32 tag, uint32 type) { return ((tag << 3) | type); } Encode32(uint32 v)70 inline void Encode32(uint32 v) { 71 if (v < 128) { 72 // Fast path for single-byte values. Many of the calls will use a 73 // constant value for v, so the comparison will get optimized away 74 // when Encode32 is inlined into the caller. 75 *p_ = v; 76 p_++; 77 } else { 78 p_ = core::EncodeVarint32(p_, v); 79 } 80 } Encode64(uint64 v)81 void Encode64(uint64 v) { p_ = core::EncodeVarint64(p_, v); } EncodeBool(bool v)82 void EncodeBool(bool v) { 83 *p_ = (v ? 1 : 0); // Equal to varint32 encoding of 0 or 1 84 p_++; 85 } EncodeBytes(const char * bytes,int N)86 void EncodeBytes(const char* bytes, int N) { 87 memcpy(p_, bytes, N); 88 p_ += N; 89 } 90 91 char* base_; 92 char* p_; 93 char* limit_; // Just for CHECKs 94 }; 95 } // namespace io 96 } // namespace tensorflow 97 98 #endif // TENSORFLOW_CORE_LIB_IO_PROTO_ENCODE_HELPER_H_ 99