fft.hpp

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#pragma once
 
#include <generic/common.hpp>
#include <generic/storage.hpp>
 
namespace Ensign {
 
/* FFT for arbitrary dimensional data, specified by dim.
   The class can also be used to e.g. perform multiple 1d FFTS on a 2d array (in this case dim=1 and d=2).
*/
template<size_t d, size_t dim>
struct fft {
 
    fft(array<Index,dim> dims_, multi_array<double,d>& real, multi_array<complex<double>,d>& freq);
    fft(array<Index,dim> dims_, multi_array<double,d>& real, multi_array<complex<double>,d>& freq,bool adapt);
    ~fft();
 
    void forward(multi_array<double,d>& real, multi_array<complex<double>,d>& freq); 
    void forward(double* real, complex<double>* freq, stloc sl);
    // Note that the backward transform overwrites the input data. This is a limitation of FFTW.
    void backward(multi_array<complex<double>,d>& freq, multi_array<double,d>& real);
    void backward(complex<double>* freq, double* real, stloc sl); 
 
private:
    array<fftw_plan,2> plans;
    #ifdef __CUDA__
    array<cufftHandle,2> cuda_plans;
    #endif
 
    void set_null() {
      plans[0] = 0;
      plans[1] = 0;
      #ifdef __CUDA__
      cuda_plans[0] = 0;
      cuda_plans[1] = 0;
      #endif
    }
};
 
template<size_t d>
using fft3d = fft<d, 3>;
 
template<size_t d>
using fft2d = fft<d, 2>;
 
template<size_t d>
using fft1d = fft<d, 1>;
 
 
/* Helper routines to create FFTW plans for 1d transforms
*/
array<fftw_plan,2> create_plans_1d(Index dims_, multi_array<double,2>& real, multi_array<complex<double>,2>& freq);
array<fftw_plan,2> create_plans_1d(Index dims_, multi_array<double,1>& real, multi_array<complex<double>,1>& freq);
 
/* Helper routines to create FFTW plans for 2d transforms
*/
array<fftw_plan,2> create_plans_2d(array<Index,2> dims_, multi_array<double,1>& real, multi_array<complex<double>,1>& freq);
array<fftw_plan,2> create_plans_2d(array<Index,2> dims_, multi_array<double,2>& real, multi_array<complex<double>,2>& freq);
 
/* Helper routines to create FFTW plans for 3d transforms
*/
array<fftw_plan,2> create_plans_3d(array<Index,3> dims_, multi_array<double,2>& real, multi_array<complex<double>,2>& freq);
array<fftw_plan,2> create_plans_3d(array<Index,3> dims_, multi_array<double,1>& real, multi_array<complex<double>,1>& freq);
array<fftw_plan,2> create_plans_3d_adapt(array<Index,3> dims_, multi_array<double,2>& real, multi_array<complex<double>,2>& freq);
 
/* Helper function to destroy FFTW plans
*/
void destroy_plans(array<fftw_plan,2>& plans);
 
 
#ifdef __CUDA__
/* Helper routines to create cuFFT plans for 1d transforms.
*/
array<cufftHandle,2> create_plans_1d(Index dims_, int howmany);
 
/* Helper routines to create cuFFT plans for 2d transforms.
*/
array<cufftHandle,2> create_plans_2d(array<Index,2> dims_, int howmany);
 
/* Helper routines to create cuFFT plans for 3d transforms.
*/
array<cufftHandle,2> create_plans_3d(array<Index,3> dims_, int howmany);
 
array<cufftHandle,2> create_plans_3d_adapt(array<Index,3> dims_);
 
/* Helper function to destroy cuFFT plans
*/
void destroy_plans(array<cufftHandle,2>& plans);
#endif
 
} // namespace Ensign