text: /*
   * Copyright (c) 2019 ETH Zurich, Simon Frasch
   *
   * 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.
   * 3. Neither the name of the copyright holder nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS 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 SPFFT_TRANSFORM_HPP
  #define SPFFT_TRANSFORM_HPP
  
  #include <memory>
  #include "spfft/config.h"
  #include "spfft/types.h"
  
  #ifdef SPFFT_MPI
  #include <mpi.h>
  #endif
  
  namespace spfft {
  
  template <typename T>
  class SPFFT_NO_EXPORT TransformInternal;
  
  class SPFFT_EXPORT Grid;
  
  template <typename TransformType>
  class SPFFT_NO_EXPORT MultiTransformInternal;
  
  template <typename T>
  class SPFFT_NO_EXPORT GridInternal;
  
  /**
   * A transform in double precision with fixed dimensions. Shares memory with other transform created
   * from the same Grid object.
   */
  class SPFFT_EXPORT Transform {
  public:
    using ValueType = double;
  
    /**
     * Default copy constructor.
     */
    Transform(const Transform&) = default;
  
    /**
     * Default move constructor.
     */
    Transform(Transform&&) = default;
  
    /**
     * Default copy operator.
     */
    Transform& operator=(const Transform&) = default;
  
    /**
     * Default move operator.
     */
    Transform& operator=(Transform&&) = default;
  
    /**
     * Clone transform.
     *
     * @return Independent transform with the same parameters, but with new underlying grid.
     */
    Transform clone() const;
  
    /**
     * Access a transform parameter.
     * @return Type of transform.
     */
    SpfftTransformType type() const;
  
    /**
     * Access a transform parameter.
     * @return Dimension in x.
     */
    int dim_x() const;
  
    /**
     * Access a transform parameter.
     * @return Dimension in y.
     */
    int dim_y() const;
  
    /**
     * Access a transform parameter.
     * @return Dimension in z.
     */
    int dim_z() const;
  
    /**
     * Access a transform parameter.
     * @return Length in z of the space domain slice held by the local MPI rank.
     */
    int local_z_length() const;
  
    /**
     * Access a transform parameter.
     * @return Offset in z of the space domain slice held by the local MPI rank.
     */
    int local_z_offset() const;
  
    /**
     * Access a transform parameter.
     * @return Number of elements in the space domain slice held by the local MPI rank.
     */
    int local_slice_size() const;
  
    /**
     * Access a transform parameter.
     * @return Global number of elements in space domain. Equals dim_x() * dim_y() * dim_z().
     */
    long long int global_size() const;
  
    /**
     * Access a transform parameter.
     * @return Number of elements in frequency domain.
     */
    int num_local_elements() const;
  
    /**
     * Access a transform parameter.
     * @return Global number of elements in frequency domain.
     */
    long long int num_global_elements() const;
  
    /**
     * Access a transform parameter.
     * @return The processing unit used for calculations. Can be SPFFT_PU_HOST or SPFFT_PU_GPU.
     */
    SpfftProcessingUnitType processing_unit() const;
  
    /**
     * Access a transform parameter.
     * @return The GPU device id used. Returns always 0, if no GPU support is enabled.
     */
    int device_id() const;
  
    /**
     * Access a transform parameter.
     * @return The exact number of threads used by transforms created from this grid. May be less than
     * the maximum given to the constructor. Always 1, if not compiled with OpenMP support.
     */
    int num_threads() const;
  
  #ifdef SPFFT_MPI
    /**
     * Access a transform parameter.
     * @return The internal MPI communicator.
     */
    MPI_Comm communicator() const;
  #endif
  
    /**
     * Provides access to the space domain data.
     *
     * @param[in] dataLocation The processing unit to query for the data. Can be SPFFT_PU_HOST or
     * SPFFT_PU_GPU (if GPU is set as execution unit).
     * @return Pointer to space domain data on given processing unit. Alignment is guaranteed to
     * fulfill requirements for std::complex and C language complex types.
     * @throw GenericError SpFFT error. Can be a derived type.
     * @throw std::exception Error from standard library calls. Can be a derived type.
     */
    double* space_domain_data(SpfftProcessingUnitType dataLocation);
  
    /**
     * Execute a forward transform from space domain to frequency domain.
     *
     * @param[in] inputLocation The processing unit, to take the input from. Can be SPFFT_PU_HOST or
     * SPFFT_PU_GPU (if GPU is set as execution unit).
     * @param[out] output Pointer to memory, where the frequency domain elements are written to. Can
     * be located at Host or GPU memory (if GPU is set as processing unit).
     * @param[in] scaling Controls scaling of output. SPFFT_NO_SCALING to disable or
     * SPFFT_FULL_SCALING to scale by factor 1 / (dim_x() * dim_y() * dim_z()).
     * @throw GenericError SpFFT error. Can be a derived type.
     * @throw std::exception Error from standard library calls. Can be a derived type.
     */
    void forward(SpfftProcessingUnitType inputLocation, double* output,
                 SpfftScalingType scaling = SPFFT_NO_SCALING);
  
    /**
     * Execute a backward transform from frequency domain to space domain.
     *
     * @param[in] input Input data in frequency domain. Must match the indices provided at transform
     * creation. Can be located at Host or GPU memory, if GPU is set as processing unit.
     * @param[in] outputLocation The processing unit, to place the output at. Can be SPFFT_PU_HOST or
     * SPFFT_PU_GPU (if GPU is set as execution unit).
     * @throw GenericError SpFFT error. Can be a derived type.
     * @throw std::exception Error from standard library calls. Can be a derived type.
     */
    void backward(const double* input, SpfftProcessingUnitType outputLocation);
  
  private:
    /*! \cond PRIVATE */
    friend Grid;
    friend MultiTransformInternal<Transform>;
  
    SPFFT_NO_EXPORT Transform(const std::shared_ptr<GridInternal<double>>& grid,
                              SpfftProcessingUnitType executionUnit, SpfftTransformType transformType,
                              int dimX, int dimY, int dimZ, int localZLength, int numLocalElements,
                              SpfftIndexFormatType dataFormat, const int* indices);
  
    SPFFT_NO_EXPORT explicit Transform(std::shared_ptr<TransformInternal<double>> transform);
  
    std::shared_ptr<TransformInternal<double>> transform_;
    /*! \endcond */
  };
  
  }  // namespace spfft
  #endif
  