Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef ANDROID_UTIL_ENCODED_BUFFER_H |
| 18 | #define ANDROID_UTIL_ENCODED_BUFFER_H |
| 19 | |
| 20 | #include <stdint.h> |
| 21 | #include <vector> |
| 22 | |
| 23 | namespace android { |
| 24 | namespace util { |
| 25 | |
| 26 | using namespace std; |
| 27 | |
| 28 | /** |
| 29 | * A stream of bytes containing a read pointer and a write pointer, |
| 30 | * backed by a set of fixed-size buffers. There are write functions for the |
| 31 | * primitive types stored by protocol buffers, but none of the logic |
| 32 | * for tags, inner objects, or any of that. |
| 33 | * |
| 34 | * Terminology: |
| 35 | * *Pos: Position in the whole data set (as if it were a single buffer). |
| 36 | * *Index: Index of a buffer within the mBuffers list. |
| 37 | * *Offset: Position within a buffer. |
| 38 | */ |
| 39 | class EncodedBuffer |
| 40 | { |
| 41 | public: |
| 42 | EncodedBuffer(); |
| 43 | EncodedBuffer(size_t chunkSize); |
| 44 | ~EncodedBuffer(); |
| 45 | |
| 46 | class Pointer { |
| 47 | public: |
| 48 | Pointer(); |
| 49 | Pointer(size_t chunkSize); |
| 50 | |
| 51 | size_t pos() const; |
| 52 | size_t index() const; |
| 53 | size_t offset() const; |
| 54 | |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 55 | Pointer* move(size_t amt); |
| 56 | inline Pointer* move() { return move(1); }; |
| 57 | Pointer* rewind(); |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 58 | |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 59 | Pointer copy() const; |
| 60 | |
| 61 | private: |
| 62 | size_t mChunkSize; |
| 63 | size_t mIndex; |
| 64 | size_t mOffset; |
| 65 | }; |
| 66 | |
Yi Jin | 7f9e63b | 2018-02-02 16:25:11 -0800 | [diff] [blame] | 67 | /** |
| 68 | * Clears the buffer by rewinding its write pointer to avoid de/allocate buffers in heap. |
| 69 | */ |
| 70 | void clear(); |
| 71 | |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 72 | /******************************** Write APIs ************************************************/ |
| 73 | |
| 74 | /** |
| 75 | * Returns the number of bytes written in the buffer |
| 76 | */ |
| 77 | size_t size() const; |
| 78 | |
| 79 | /** |
| 80 | * Returns the write pointer. |
| 81 | */ |
| 82 | Pointer* wp(); |
| 83 | |
| 84 | /** |
| 85 | * Returns the current position of write pointer, if the write buffer is full, it will automatically |
| 86 | * rotate to a new buffer with given chunkSize. If NULL is returned, it means NO_MEMORY |
| 87 | */ |
| 88 | uint8_t* writeBuffer(); |
| 89 | |
| 90 | /** |
| 91 | * Returns the writeable size in the current write buffer . |
| 92 | */ |
| 93 | size_t currentToWrite(); |
| 94 | |
| 95 | /** |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 96 | * Write a single byte to the buffer. |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 97 | */ |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 98 | void writeRawByte(uint8_t val); |
| 99 | |
| 100 | /** |
| 101 | * Write a varint32 into the buffer. Return the size of the varint. |
| 102 | */ |
| 103 | size_t writeRawVarint32(uint32_t val); |
| 104 | |
| 105 | /** |
| 106 | * Write a varint64 into the buffer. Return the size of the varint. |
| 107 | */ |
| 108 | size_t writeRawVarint64(uint64_t val); |
| 109 | |
| 110 | /** |
| 111 | * Write Fixed32 into the buffer. |
| 112 | */ |
| 113 | void writeRawFixed32(uint32_t val); |
| 114 | |
| 115 | /** |
| 116 | * Write Fixed64 into the buffer. |
| 117 | */ |
| 118 | void writeRawFixed64(uint64_t val); |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 119 | |
| 120 | /** |
| 121 | * Write a protobuf header. Return the size of the header. |
| 122 | */ |
| 123 | size_t writeHeader(uint32_t fieldId, uint8_t wireType); |
| 124 | |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 125 | /********************************* Edit APIs ************************************************/ |
| 126 | /** |
| 127 | * Returns the edit pointer. |
| 128 | */ |
| 129 | Pointer* ep(); |
| 130 | |
| 131 | /** |
| 132 | * Read a single byte at ep, and move ep to next byte; |
| 133 | */ |
| 134 | uint8_t readRawByte(); |
| 135 | |
| 136 | /** |
| 137 | * Read varint starting at ep, ep will move to pos of next byte. |
| 138 | */ |
| 139 | uint64_t readRawVarint(); |
| 140 | |
| 141 | /** |
| 142 | * Read 4 bytes starting at ep, ep will move to pos of next byte. |
| 143 | */ |
| 144 | uint32_t readRawFixed32(); |
| 145 | |
| 146 | /** |
| 147 | * Read 8 bytes starting at ep, ep will move to pos of next byte. |
| 148 | */ |
| 149 | uint64_t readRawFixed64(); |
| 150 | |
| 151 | /** |
| 152 | * Edit 4 bytes starting at pos. |
| 153 | */ |
| 154 | void editRawFixed32(size_t pos, uint32_t val); |
| 155 | |
| 156 | /** |
| 157 | * Copy _size_ bytes of data starting at __srcPos__ to wp. |
| 158 | */ |
| 159 | void copy(size_t srcPos, size_t size); |
| 160 | |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 161 | /********************************* Read APIs ************************************************/ |
| 162 | class iterator; |
| 163 | friend class iterator; |
| 164 | class iterator { |
| 165 | public: |
| 166 | iterator(const EncodedBuffer& buffer); |
| 167 | |
| 168 | /** |
| 169 | * Returns the number of bytes written in the buffer |
| 170 | */ |
| 171 | size_t size() const; |
| 172 | |
| 173 | /** |
| 174 | * Returns the size of total bytes read. |
| 175 | */ |
| 176 | size_t bytesRead() const; |
| 177 | |
| 178 | /** |
| 179 | * Returns the read pointer. |
| 180 | */ |
| 181 | Pointer* rp(); |
| 182 | |
| 183 | /** |
| 184 | * Returns the current position of read pointer, if NULL is returned, it reaches end of buffer. |
| 185 | */ |
| 186 | uint8_t const* readBuffer(); |
| 187 | |
| 188 | /** |
| 189 | * Returns the readable size in the current read buffer. |
| 190 | */ |
| 191 | size_t currentToRead(); |
| 192 | |
| 193 | /** |
| 194 | * Returns true if next bytes is available for read. |
| 195 | */ |
| 196 | bool hasNext(); |
| 197 | |
| 198 | /** |
| 199 | * Reads the current byte and moves pointer 1 bit. |
| 200 | */ |
| 201 | uint8_t next(); |
| 202 | |
| 203 | /** |
| 204 | * Read varint from iterator, the iterator will point to next available byte. |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 205 | */ |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 206 | uint64_t readRawVarint(); |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 207 | |
| 208 | private: |
| 209 | const EncodedBuffer& mData; |
| 210 | Pointer mRp; |
| 211 | }; |
| 212 | |
| 213 | /** |
| 214 | * Returns the iterator of EncodedBuffer so it guarantees consumers won't be able to modified the buffer. |
| 215 | */ |
| 216 | iterator begin() const; |
| 217 | |
| 218 | private: |
| 219 | size_t mChunkSize; |
| 220 | vector<uint8_t*> mBuffers; |
| 221 | |
| 222 | Pointer mWp; |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 223 | Pointer mEp; |
Yi Jin | c23fad2 | 2017-09-15 17:24:59 -0700 | [diff] [blame] | 224 | |
| 225 | inline uint8_t* at(const Pointer& p) const; // helper function to get value |
| 226 | }; |
| 227 | |
| 228 | } // util |
| 229 | } // android |
| 230 | |
Yi Jin | 974a9c2 | 2017-10-02 18:37:08 -0700 | [diff] [blame] | 231 | #endif // ANDROID_UTIL_ENCODED_BUFFER_H |
| 232 | |