FFTW.h

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// # Copyright (C) 1993,1994,1995,1997,1999,2000,2001
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library 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 Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
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#ifndef SCIMATH_FFTW_H
#define SCIMATH_FFTW_H
 
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/IPosition.h>
 
#include <complex>
#include <memory>
#include <mutex>
 
namespace casacore {
 
// # Forward Declarations.
class FFTWPlan;
class FFTWPlanf;
 
// <summary> C++ interface to the FFTWw library </summary>
// <reviewed reviewer="NONE" date="" tests="" demos="">
// </reviewed>
// <synopsis>
// This is a wrapper of FFTW3.
// It is only active if FFTW3 was found during the build.
// If not found, all functions won't do anything at all.
//
// The interface is such that the presence of FFTW3 is only visible
// in the implementation. The header file does not need to know.
// In this way external code using this class does not need to set HAVE_FFTW.
// </synopsis>
 
class FFTW {
 public:
  FFTW();
 
  ~FFTW();
 
  // overloaded interface to fftw[f]_plan...
  void plan_r2c(const IPosition &size, float *in, std::complex<float> *out);
  void plan_r2c(const IPosition &size, double *in, std::complex<double> *out);
  void plan_c2r(const IPosition &size, std::complex<float> *in, float *out);
  void plan_c2r(const IPosition &size, std::complex<double> *in, double *out);
  void plan_c2c_forward(const IPosition &size, std::complex<double> *in);
  void plan_c2c_forward(const IPosition &size, std::complex<float> *in);
  void plan_c2c_backward(const IPosition &size, std::complex<double> *in);
  void plan_c2c_backward(const IPosition &size, std::complex<float> *in);
 
  // TODO These overloads do not use their parameters at all. This should
  // be written to use an interface like plan_redft00().
  // overloaded interface to fftw[f]_execute...
  void r2c(const IPosition &size, float *in, std::complex<float> *out);
  void r2c(const IPosition &size, double *in, std::complex<double> *out);
  void c2r(const IPosition &size, std::complex<float> *in, float *out);
  void c2r(const IPosition &size, std::complex<double> *in, double *out);
  void c2c(const IPosition &size, std::complex<float> *in, bool forward);
  void c2c(const IPosition &size, std::complex<double> *in, bool forward);
 
  class Plan {
   public:
    ~Plan() noexcept;
    Plan(const Plan &) = delete;
    Plan(Plan &&);
    Plan &operator=(const Plan &) = delete;
    Plan &operator=(Plan &&);
 
    // Perform the FFT associated with this plan with the given
    // in data, and store it in the given out data.
    // <group>
    void Execute(float *in, float *out);
    void Execute(double *in, double *out);
    // </group>
   private:
    friend FFTW;
    Plan(FFTWPlan *plan);
    Plan(FFTWPlanf *plan);
    std::unique_ptr<FFTWPlan> _plan;
    std::unique_ptr<FFTWPlanf> _planf;
  };
 
  static Plan plan_redft00(const IPosition &size, float *in, float *out);
  static Plan plan_redft00(const IPosition &size, double *in, double *out);
 
 private:
  static void initialize_fftw();
 
  std::unique_ptr<FFTWPlanf> itsPlanR2Cf;
  std::unique_ptr<FFTWPlan> itsPlanR2C;
 
  std::unique_ptr<FFTWPlanf> itsPlanC2Rf;
  std::unique_ptr<FFTWPlan> itsPlanC2R;
 
  std::unique_ptr<FFTWPlanf> itsPlanC2CFf;  // forward
  std::unique_ptr<FFTWPlan> itsPlanC2CF;
 
  std::unique_ptr<FFTWPlanf> itsPlanC2CBf;  // backward
  std::unique_ptr<FFTWPlan> itsPlanC2CB;
 
  std::unique_ptr<FFTWPlanf> itsPlanR2Rf;
  std::unique_ptr<FFTWPlan> itsPlanR2R;
 
  unsigned flags;
 
  static bool is_initialized_fftw;  // FFTW needs initialization
                                    // only once per process,
                                    // not once per object
 
  // TODO this mutex does not make FFTW thread safe, because
  // planning an FFT with FFTW is not thread safe either.
  // So either the plan..() methods should take the mutex, or
  // FFTW should leave synchronization fully to the user of
  // this class: currently it's halfway in between.
  static std::mutex theirMutex;  // Initialization mutex
};
 
}  // namespace casacore
 
#endif