fft_utils.hpp

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#pragma once
 
#include <oneapi/mkl.hpp>
 
namespace dpnp::extensions::fft
{
namespace mkl_dft = oneapi::mkl::dft;
 
// Structure to map MKL precision to float/double types
template <mkl_dft::precision prec>
struct PrecisionType;
 
template <>
struct PrecisionType<mkl_dft::precision::SINGLE>
{
    using type = float;
};
 
template <>
struct PrecisionType<mkl_dft::precision::DOUBLE>
{
    using type = double;
};
 
// Structure to map combination of precision, domain, and is_forward flag to
// in/out types
template <mkl_dft::precision prec, mkl_dft::domain dom, bool is_forward>
struct ScaleType
{
    using type_in = void;
    using type_out = void;
};
 
// for r2c FFT, type_in is real and type_out is complex
// is_forward is true
template <mkl_dft::precision prec>
struct ScaleType<prec, mkl_dft::domain::REAL, true>
{
    using prec_type = typename PrecisionType<prec>::type;
    using type_in = prec_type;
    using type_out = std::complex<prec_type>;
};
 
// for c2r FFT, type_in is complex and type_out is real
// is_forward is false
template <mkl_dft::precision prec>
struct ScaleType<prec, mkl_dft::domain::REAL, false>
{
    using prec_type = typename PrecisionType<prec>::type;
    using type_in = std::complex<prec_type>;
    using type_out = prec_type;
};
 
// for c2c FFT, both type_in and type_out are complex
// regardless of is_fwd
template <mkl_dft::precision prec, bool is_fwd>
struct ScaleType<prec, mkl_dft::domain::COMPLEX, is_fwd>
{
    using prec_type = typename PrecisionType<prec>::type;
    using type_in = std::complex<prec_type>;
    using type_out = std::complex<prec_type>;
};
} // namespace dpnp::extensions::fft