text: /***********************************************************************
   * Software License Agreement (BSD License)
   *
   * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
   * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE NNIndexGOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *************************************************************************/
  
  #ifndef OPENCV_FLANN_SAVING_H_
  #define OPENCV_FLANN_SAVING_H_
  
  #include <cstring>
  #include <vector>
  
  #include "general.h"
  #include "nn_index.h"
  
  #ifdef FLANN_SIGNATURE_
  #undef FLANN_SIGNATURE_
  #endif
  #define FLANN_SIGNATURE_ "FLANN_INDEX"
  
  namespace cvflann
  {
  
  template <typename T>
  struct Datatype {};
  template<>
  struct Datatype<char> { static flann_datatype_t type() { return FLANN_INT8; } };
  template<>
  struct Datatype<short> { static flann_datatype_t type() { return FLANN_INT16; } };
  template<>
  struct Datatype<int> { static flann_datatype_t type() { return FLANN_INT32; } };
  template<>
  struct Datatype<unsigned char> { static flann_datatype_t type() { return FLANN_UINT8; } };
  template<>
  struct Datatype<unsigned short> { static flann_datatype_t type() { return FLANN_UINT16; } };
  template<>
  struct Datatype<unsigned int> { static flann_datatype_t type() { return FLANN_UINT32; } };
  template<>
  struct Datatype<float> { static flann_datatype_t type() { return FLANN_FLOAT32; } };
  template<>
  struct Datatype<double> { static flann_datatype_t type() { return FLANN_FLOAT64; } };
  
  
  /**
   * Structure representing the index header.
   */
  struct IndexHeader
  {
      char signature[16];
      char version[16];
      flann_datatype_t data_type;
      flann_algorithm_t index_type;
      size_t rows;
      size_t cols;
  };
  
  /**
   * Saves index header to stream
   *
   * @param stream - Stream to save to
   * @param index - The index to save
   */
  template<typename Distance>
  void save_header(FILE* stream, const NNIndex<Distance>& index)
  {
      IndexHeader header;
      memset(header.signature, 0, sizeof(header.signature));
      strcpy(header.signature, FLANN_SIGNATURE_);
      memset(header.version, 0, sizeof(header.version));
      strcpy(header.version, FLANN_VERSION_);
      header.data_type = Datatype<typename Distance::ElementType>::type();
      header.index_type = index.getType();
      header.rows = index.size();
      header.cols = index.veclen();
  
      std::fwrite(&header, sizeof(header),1,stream);
  }
  
  
  /**
   *
   * @param stream - Stream to load from
   * @return Index header
   */
  inline IndexHeader load_header(FILE* stream)
  {
      IndexHeader header;
      size_t read_size = fread(&header,sizeof(header),1,stream);
  
      if (read_size!=(size_t)1) {
          throw FLANNException("Invalid index file, cannot read");
      }
  
      if (strcmp(header.signature,FLANN_SIGNATURE_)!=0) {
          throw FLANNException("Invalid index file, wrong signature");
      }
  
      return header;
  
  }
  
  
  template<typename T>
  void save_value(FILE* stream, const T& value, size_t count = 1)
  {
      fwrite(&value, sizeof(value),count, stream);
  }
  
  template<typename T>
  void save_value(FILE* stream, const cvflann::Matrix<T>& value)
  {
      fwrite(&value, sizeof(value),1, stream);
      fwrite(value.data, sizeof(T),value.rows*value.cols, stream);
  }
  
  template<typename T>
  void save_value(FILE* stream, const std::vector<T>& value)
  {
      size_t size = value.size();
      fwrite(&size, sizeof(size_t), 1, stream);
      fwrite(&value[0], sizeof(T), size, stream);
  }
  
  template<typename T>
  void load_value(FILE* stream, T& value, size_t count = 1)
  {
      size_t read_cnt = fread(&value, sizeof(value), count, stream);
      if (read_cnt != count) {
          throw FLANNException("Cannot read from file");
      }
  }
  
  template<typename T>
  void load_value(FILE* stream, cvflann::Matrix<T>& value)
  {
      size_t read_cnt = fread(&value, sizeof(value), 1, stream);
      if (read_cnt != 1) {
          throw FLANNException("Cannot read from file");
      }
      value.data = new T[value.rows*value.cols];
      read_cnt = fread(value.data, sizeof(T), value.rows*value.cols, stream);
      if (read_cnt != (size_t)(value.rows*value.cols)) {
          throw FLANNException("Cannot read from file");
      }
  }
  
  
  template<typename T>
  void load_value(FILE* stream, std::vector<T>& value)
  {
      size_t size;
      size_t read_cnt = fread(&size, sizeof(size_t), 1, stream);
      if (read_cnt!=1) {
          throw FLANNException("Cannot read from file");
      }
      value.resize(size);
      read_cnt = fread(&value[0], sizeof(T), size, stream);
      if (read_cnt != size) {
          throw FLANNException("Cannot read from file");
      }
  }
  
  }
  
  #endif /* OPENCV_FLANN_SAVING_H_ */
  
  