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Diffstat (limited to 'libs/protoutil/include/android/util/EncodedBuffer.h')
| -rw-r--r-- | libs/protoutil/include/android/util/EncodedBuffer.h | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/libs/protoutil/include/android/util/EncodedBuffer.h b/libs/protoutil/include/android/util/EncodedBuffer.h new file mode 100644 index 000000000000..cf096091c055 --- /dev/null +++ b/libs/protoutil/include/android/util/EncodedBuffer.h @@ -0,0 +1,170 @@ +/* + * 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; + + void move(size_t amt); + inline void move() { move(1); }; + + void rewind(); + Pointer copy() const; + + private: + size_t mChunkSize; + size_t mIndex; + size_t mOffset; + }; + + /******************************** 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 varint into a vector. Return the size of the varint. + */ + size_t writeRawVarint(uint32_t val); + + /** + * Write a protobuf header. Return the size of the header. + */ + size_t writeHeader(uint32_t fieldId, uint8_t wireType); + + /********************************* 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. + * Return the number of bytes of the varint. + */ + uint32_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; + + inline uint8_t* at(const Pointer& p) const; // helper function to get value +}; + +} // util +} // android + +#endif // ANDROID_UTIL_ENCODED_BUFFER_H
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