| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ANDROID_UTIL_ENCODED_BUFFER_H |
| #define ANDROID_UTIL_ENCODED_BUFFER_H |
| |
| #include <stdint.h> |
| #include <vector> |
| |
| namespace android { |
| namespace util { |
| |
| using namespace std; |
| |
| /** |
| * A stream of bytes containing a read pointer and a write pointer, |
| * backed by a set of fixed-size buffers. There are write functions for the |
| * primitive types stored by protocol buffers, but none of the logic |
| * for tags, inner objects, or any of that. |
| * |
| * Terminology: |
| * *Pos: Position in the whole data set (as if it were a single buffer). |
| * *Index: Index of a buffer within the mBuffers list. |
| * *Offset: Position within a buffer. |
| */ |
| class EncodedBuffer |
| { |
| public: |
| EncodedBuffer(); |
| EncodedBuffer(size_t chunkSize); |
| ~EncodedBuffer(); |
| |
| class Pointer { |
| public: |
| Pointer(); |
| Pointer(size_t chunkSize); |
| |
| size_t pos() const; |
| size_t index() const; |
| size_t offset() const; |
| |
| Pointer* move(size_t amt); |
| inline Pointer* move() { return move(1); }; |
| Pointer* rewind(); |
| |
| Pointer copy() const; |
| |
| private: |
| size_t mChunkSize; |
| size_t mIndex; |
| size_t mOffset; |
| }; |
| |
| /** |
| * Clears the buffer by rewinding its write pointer to avoid de/allocate buffers in heap. |
| */ |
| void clear(); |
| |
| /******************************** Write APIs ************************************************/ |
| |
| /** |
| * Returns the number of bytes written in the buffer |
| */ |
| size_t size() const; |
| |
| /** |
| * Returns the write pointer. |
| */ |
| Pointer* wp(); |
| |
| /** |
| * Returns the current position of write pointer, if the write buffer is full, it will automatically |
| * rotate to a new buffer with given chunkSize. If NULL is returned, it means NO_MEMORY |
| */ |
| uint8_t* writeBuffer(); |
| |
| /** |
| * Returns the writeable size in the current write buffer . |
| */ |
| size_t currentToWrite(); |
| |
| /** |
| * Write a single byte to the buffer. |
| */ |
| void writeRawByte(uint8_t val); |
| |
| /** |
| * Write a varint32 into the buffer. Return the size of the varint. |
| */ |
| size_t writeRawVarint32(uint32_t val); |
| |
| /** |
| * Write a varint64 into the buffer. Return the size of the varint. |
| */ |
| size_t writeRawVarint64(uint64_t val); |
| |
| /** |
| * Write Fixed32 into the buffer. |
| */ |
| void writeRawFixed32(uint32_t val); |
| |
| /** |
| * Write Fixed64 into the buffer. |
| */ |
| void writeRawFixed64(uint64_t val); |
| |
| /** |
| * Write a protobuf header. Return the size of the header. |
| */ |
| size_t writeHeader(uint32_t fieldId, uint8_t wireType); |
| |
| /********************************* Edit APIs ************************************************/ |
| /** |
| * Returns the edit pointer. |
| */ |
| Pointer* ep(); |
| |
| /** |
| * Read a single byte at ep, and move ep to next byte; |
| */ |
| uint8_t readRawByte(); |
| |
| /** |
| * Read varint starting at ep, ep will move to pos of next byte. |
| */ |
| uint64_t readRawVarint(); |
| |
| /** |
| * Read 4 bytes starting at ep, ep will move to pos of next byte. |
| */ |
| uint32_t readRawFixed32(); |
| |
| /** |
| * Read 8 bytes starting at ep, ep will move to pos of next byte. |
| */ |
| uint64_t readRawFixed64(); |
| |
| /** |
| * Edit 4 bytes starting at pos. |
| */ |
| void editRawFixed32(size_t pos, uint32_t val); |
| |
| /** |
| * Copy _size_ bytes of data starting at __srcPos__ to wp, srcPos must be larger than wp.pos(). |
| */ |
| void copy(size_t srcPos, size_t size); |
| |
| /********************************* Read APIs ************************************************/ |
| class iterator; |
| friend class iterator; |
| class iterator { |
| public: |
| iterator(const EncodedBuffer& buffer); |
| |
| /** |
| * Returns the number of bytes written in the buffer |
| */ |
| size_t size() const; |
| |
| /** |
| * Returns the size of total bytes read. |
| */ |
| size_t bytesRead() const; |
| |
| /** |
| * Returns the read pointer. |
| */ |
| Pointer* rp(); |
| |
| /** |
| * Returns the current position of read pointer, if NULL is returned, it reaches end of buffer. |
| */ |
| uint8_t const* readBuffer(); |
| |
| /** |
| * Returns the readable size in the current read buffer. |
| */ |
| size_t currentToRead(); |
| |
| /** |
| * Returns true if next bytes is available for read. |
| */ |
| bool hasNext(); |
| |
| /** |
| * Reads the current byte and moves pointer 1 bit. |
| */ |
| uint8_t next(); |
| |
| /** |
| * Read varint from iterator, the iterator will point to next available byte. |
| */ |
| uint64_t readRawVarint(); |
| |
| private: |
| const EncodedBuffer& mData; |
| Pointer mRp; |
| }; |
| |
| /** |
| * Returns the iterator of EncodedBuffer so it guarantees consumers won't be able to modified the buffer. |
| */ |
| iterator begin() const; |
| |
| private: |
| size_t mChunkSize; |
| vector<uint8_t*> mBuffers; |
| |
| Pointer mWp; |
| Pointer mEp; |
| |
| inline uint8_t* at(const Pointer& p) const; // helper function to get value |
| }; |
| |
| } // util |
| } // android |
| |
| #endif // ANDROID_UTIL_ENCODED_BUFFER_H |
| |