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      1 // Copyright 2017 The Chromium OS Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef SRC_PUFF_READER_H_
      6 #define SRC_PUFF_READER_H_
      7 
      8 #include <cstddef>
      9 #include <cstdint>
     10 
     11 #include "puffin/src/include/puffin/common.h"
     12 #include "puffin/src/include/puffin/errors.h"
     13 #include "puffin/src/puff_data.h"
     14 
     15 namespace puffin {
     16 
     17 // An abstract class for reading data from a puffed buffer. Data can be
     18 // literals, lengths, distances, or metadata. Extensions of this class can
     19 // define how the puffed data should reside in the puffed buffer.
     20 class PuffReaderInterface {
     21  public:
     22   virtual ~PuffReaderInterface() = default;
     23 
     24   // Retrieves the next puff data available in the puffed buffer. Similar to
     25   // |PuffWriterInterface.Insert()| This function does not check for validity of
     26   // data.
     27   //
     28   // |data|  OUT  The next data available in the puffed buffer.
     29   // |error| OUT  The error code.
     30   virtual bool GetNext(PuffData* data, Error* error) = 0;
     31 
     32   // Returns the number of bytes left in the puff buffer.
     33   virtual size_t BytesLeft() const = 0;
     34 };
     35 
     36 class BufferPuffReader : public PuffReaderInterface {
     37  public:
     38   // Sets the parameters of puff buffer.
     39   //
     40   // |puff_buf|  IN  The input puffed stream. It is owned by the caller and must
     41   //                 be valid during the lifetime of the object.
     42   // |puff_size| IN  The size of the puffed stream.
     43   BufferPuffReader(const uint8_t* puff_buf, size_t puff_size)
     44       : puff_buf_in_(puff_buf),
     45         puff_size_(puff_size),
     46         index_(0),
     47         state_(State::kReadingBlockMetadata) {}
     48 
     49   ~BufferPuffReader() override = default;
     50 
     51   bool GetNext(PuffData* pd, Error* error) override;
     52   size_t BytesLeft() const override;
     53 
     54  private:
     55   // The pointer to the puffed stream. This should not be deallocated.
     56   const uint8_t* puff_buf_in_;
     57 
     58   // The size of the puffed buffer.
     59   size_t puff_size_;
     60 
     61   // Index to the offset of the next data in the puff buffer.
     62   size_t index_;
     63 
     64   // State when reading from the puffed buffer.
     65   enum class State {
     66     kReadingLenDist = 0,
     67     kReadingBlockMetadata,
     68   } state_;
     69 
     70   DISALLOW_COPY_AND_ASSIGN(BufferPuffReader);
     71 };
     72 
     73 }  // namespace puffin
     74 
     75 #endif  // SRC_PUFF_READER_H_
     76