SparseBuffer.h

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/*
 *    Copyright (C) 2016-2026 Grok Image Compression Inc.
 *
 *    This source code is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This source code is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
 
#pragma once
 
#include <vector>
#include <stdexcept>
#include <mutex>
 
#include "buffer.h"
 
namespace grk
{
 
class SparseBufferIncompleteException : public std::runtime_error
{
public:
  SparseBufferIncompleteException();
};

class SparseBuffer
{
public:
  SparseBuffer();
  virtual ~SparseBuffer();

  virtual void rewind(void);

  size_t skip(size_t numBytes);

  size_t read(void* buffer, size_t numBytes);

  size_t length(void) const;

  Buffer8* push(uint8_t* buf, size_t len, bool ownsData);

  Buffer8* push(size_t index, uint8_t* buf, size_t len, bool ownsData);

  virtual void chunkSkip(size_t offset);

  size_t chunkLength(void);

  uint8_t* chunkPtr(void);
 
  bool empty(void) const
  {
    return chunks.empty();
  }
 
private:
  enum class Mode
  {
    Unset,
    Sequential,
    Indexed
  };

  void tryIncrement(void);

  size_t offset(void);

  bool copyDataChunksToContiguous(uint8_t* buffer);

  void cleanup(void);

  size_t chunkOffset(void);

  size_t dataLen;

  size_t currentChunkId;

  std::vector<Buffer8*> chunks;

  bool reachedEnd_;

  Mode mode_;

  std::mutex mutex_;
};
 
} // namespace grk