PacketLengthCache.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 <map>
 
namespace grk
{

template<typename T>
class PacketLengthCache
{
public:
  PacketLengthCache(CodingParams* cp);

  virtual ~PacketLengthCache();

  PLMarker* createMarkers(IStream* strm);

  PLMarker* getMarkers(void) const;

  void deleteMarkers(void);

  T next(void);

  void rewind(void);
 
private:
  PLMarker* plMarkers_;

  CodingParams* cp_;
};
 
template<typename T>
PacketLengthCache<T>::PacketLengthCache(CodingParams* cp) : plMarkers_(nullptr), cp_(cp)
{}
template<typename T>
PacketLengthCache<T>::~PacketLengthCache()
{
  delete plMarkers_;
}
 
template<typename T>
PLMarker* PacketLengthCache<T>::createMarkers(IStream* strm)
{
  if(!plMarkers_)
    plMarkers_ = strm ? new PLMarker(strm) : new PLMarker();
 
  return plMarkers_;
}
 
template<typename T>
PLMarker* PacketLengthCache<T>::getMarkers(void) const
{
  return plMarkers_;
}
 
template<typename T>
void PacketLengthCache<T>::deleteMarkers(void)
{
  delete plMarkers_;
  plMarkers_ = nullptr;
}
 
template<typename T>
T PacketLengthCache<T>::next()
{
  // we don't currently support PLM markers,
  // so we disable packet length markers if we have both PLT and PLM
  bool usePlt = plMarkers_ && !cp_->plmMarkers_ && plMarkers_->isEnabled();
  if(usePlt)
  {
    T len = plMarkers_->pop();
    if(len == 0)
      grklog.error("PLT marker: missing packet lengths.");
    return len;
  }
  return 0;
}
 
template<typename T>
void PacketLengthCache<T>::rewind(void)
{
  // we don't currently support PLM markers,
  // so we disable packet length markers if we have both PLT and PLM
  if(plMarkers_ && !cp_->plmMarkers_)
    plMarkers_->rewind();
}
 
} // namespace grk