contrib/Eigen/src/FFT/pocketfft_impl.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// SPDX-FileCopyrightText: The Eigen Authors
// SPDX-License-Identifier: MPL-2.0

#ifndef EIGEN_FFT_POCKETFFT_IMPL_H
#define EIGEN_FFT_POCKETFFT_IMPL_H

namespace Eigen {

namespace internal {

template <typename _Scalar>
struct pocketfft_impl {
  using Scalar = _Scalar;
  using Complex = std::complex<Scalar>;
  using shape_t = pocketfft::shape_t;
  using stride_t = pocketfft::stride_t;

  inline void clear() {}

  inline void fwd(Complex* dst, const Scalar* src, int nfft) {
    const shape_t shape_{static_cast<size_t>(nfft)};
    const shape_t axes_{0};
    const stride_t stride_in{sizeof(Scalar)};
    const stride_t stride_out{sizeof(Complex)};
    pocketfft::r2c(shape_, stride_in, stride_out, axes_, pocketfft::FORWARD, src, dst, static_cast<Scalar>(1));
  }

  inline void fwd(Complex* dst, const Complex* src, int nfft) {
    const shape_t shape_{static_cast<size_t>(nfft)};
    const shape_t axes_{0};
    const stride_t stride_{sizeof(Complex)};
    pocketfft::c2c(shape_, stride_, stride_, axes_, pocketfft::FORWARD, src, dst, static_cast<Scalar>(1));
  }

  inline void inv(Scalar* dst, const Complex* src, int nfft) {
    const shape_t shape_{static_cast<size_t>(nfft)};
    const shape_t axes_{0};
    const stride_t stride_in{sizeof(Complex)};
    const stride_t stride_out{sizeof(Scalar)};
    pocketfft::c2r(shape_, stride_in, stride_out, axes_, pocketfft::BACKWARD, src, dst, static_cast<Scalar>(1));
  }

  inline void inv(Complex* dst, const Complex* src, int nfft) {
    const shape_t shape_{static_cast<size_t>(nfft)};
    const shape_t axes_{0};
    const stride_t stride_{sizeof(Complex)};
    pocketfft::c2c(shape_, stride_, stride_, axes_, pocketfft::BACKWARD, src, dst, static_cast<Scalar>(1));
  }

  inline void fwd2(Complex* dst, const Complex* src, int nfft0, int nfft1) {
    const shape_t shape_{static_cast<size_t>(nfft0), static_cast<size_t>(nfft1)};
    const shape_t axes_{0, 1};
    const stride_t stride_{static_cast<ptrdiff_t>(sizeof(Complex) * nfft1), static_cast<ptrdiff_t>(sizeof(Complex))};
    pocketfft::c2c(shape_, stride_, stride_, axes_, pocketfft::FORWARD, src, dst, static_cast<Scalar>(1));
  }

  inline void inv2(Complex* dst, const Complex* src, int nfft0, int nfft1) {
    const shape_t shape_{static_cast<size_t>(nfft0), static_cast<size_t>(nfft1)};
    const shape_t axes_{0, 1};
    const stride_t stride_{static_cast<ptrdiff_t>(sizeof(Complex) * nfft1), static_cast<ptrdiff_t>(sizeof(Complex))};
    pocketfft::c2c(shape_, stride_, stride_, axes_, pocketfft::BACKWARD, src, dst, static_cast<Scalar>(1));
  }
};

}  // namespace internal
}  // namespace Eigen

#endif  // EIGEN_FFT_POCKETFFT_IMPL_H