Host FFTW transforms and Kokkos/FFTW layout conversion. More...

#include "fft_wrapper.hpp"

Static Public Member Functions
static void	bspl2fft_2d (const Kokkos::View< Real > &bspl_data, Kokkos::View< Complex > &fft_data, int nchi, int nphi)
	Compute an unnormalized full complex 2-D FFT of a real surface.

static void	bspl2fft_3d (const Kokkos::View< Real * > &bspl_data, Kokkos::View< Complex > &fft_data, int ns, int nchi, int nphi, int neq_f, const Kokkos::View< int *** > filter=nullptr, const Kokkos::View< Real > fftminv=nullptr, const Kokkos::View< int * > mmin_f=nullptr, const Kokkos::View< int * > *mmax_f=nullptr)
	Transform radial B-spline surfaces to packed Fourier coefficients.

static std::size_t	cached_plan_count_2d_backward ()
	Inspect the number of cached backward 2-D transform sizes.

static std::size_t	cached_plan_count_2d_forward ()
	Inspect the number of cached forward 2-D transform sizes.

static void	copy_complex_from_fftw (fftw_complex fftw_data, const Kokkos::View< Complex * > &kokkos_data, int neq_f, int nphi)
	Copy FFTW host storage into a packed complex Kokkos View.

static void	copy_complex_to_fftw (const Kokkos::View< Complex ** > &kokkos_data, fftw_complex *fftw_data, int neq_f, int nphi)
	Copy a packed complex Kokkos View to FFTW host storage.

static void	copy_from_fftw (fftw_complex fftw_data, const Kokkos::View< Real ** > &kokkos_data, int ns, int nchi, int nphi)
	Copy real components from FFTW storage into a 3-D Kokkos View.

static void	copy_to_fftw (const Kokkos::View< Real *** > &kokkos_data, fftw_complex *fftw_data, int ns, int nchi, int nphi)
	Copy a real 3-D Kokkos View to complex FFTW host storage.

static void	destroy_plan (fftw_plan plan)
	Destroy a caller-owned FFTW plan when non-null.

static void	execute_backward (fftw_plan plan)
	Execute a previously created FFTW backward plan.

static void	execute_forward (fftw_plan plan)
	Execute a previously created FFTW forward plan.

static void	fft2bspl_2d (const Kokkos::View< Complex > &fft_data, Kokkos::View< Real > &bspl_data, int nchi, int nphi)
	Compute the normalized real inverse of a full 2-D spectrum.

static void	fft2bspl_3d (const Kokkos::View< Complex > &fft_data, Kokkos::View< Real * > &bspl_data, int ns, int nchi, int nphi, int neq_f, const Kokkos::View< int ** > mmin_f=nullptr, const Kokkos::View< int * > mmax_f=nullptr, bool reconstruct_hermitian_toroidal=false, const char trace_tag=nullptr)
	Reconstruct real B-spline surfaces from packed Fourier modes.

static void	init_1d_backward (int n, fftw_plan &plan_backward, fftw_complex in, fftw_complex out)
	Create an unnormalized 1-D backward complex FFTW plan.

static void	init_1d_forward (int n, fftw_plan &plan_forward, fftw_complex in, fftw_complex out)
	Create an unnormalized 1-D forward complex FFTW plan.

static void	init_2d_backward (int nchi, int nphi, fftw_plan &plan_backward, fftw_complex in, fftw_complex out)
	Create an unnormalized backward FFT over `(chi,phi)`.

static void	init_2d_forward (int nchi, int nphi, fftw_plan &plan_forward, fftw_complex in, fftw_complex out)
	Create an unnormalized forward FFT over `(chi,phi)`.

Detailed Description

Host FFTW transforms and Kokkos/FFTW layout conversion.

ORB5X stores periodic poloidal (chi) and toroidal (phi) data in Kokkos Views but currently executes transforms with double-complex FFTW plans on host buffers. Flattening is row-major with phi fastest. The raw plan helpers follow FFTW's unnormalized convention; the higher-level 2-D and 3-D pairs apply normalization as documented on each function.

Cached 2-D plans are protected by a mutex and released at process shutdown. They remain FFTW host plans and do not provide device-resident transforms.

Member Function Documentation

◆ bspl2fft_2d()

static void orb5x::FFTWrapper::bspl2fft_2d	(	const Kokkos::View< Real ** > &	bspl_data,
		Kokkos::View< Complex ** > &	fft_data,
		int	nchi,
		int	nphi
	)

static

Compute an unnormalized full complex 2-D FFT of a real surface.

Parameters

[in]	bspl_data	Real input `[chi][phi]`.
[out]	fft_data	Full complex spectrum `[chi mode][phi mode]`.
[in]	nchi	Poloidal extent.
[in]	nphi	Toroidal extent.

Referenced by orb5x::bspl2fft_2d().

◆ bspl2fft_3d()

static void orb5x::FFTWrapper::bspl2fft_3d	(	const Kokkos::View< Real *** > &	bspl_data,
		Kokkos::View< Complex ** > &	fft_data,
		int	ns,
		int	nchi,
		int	nphi,
		int	neq_f,
		const Kokkos::View< int *** > *	filter = `nullptr`,
		const Kokkos::View< Real * > *	fftminv = `nullptr`,
		const Kokkos::View< int ** > *	mmin_f = `nullptr`,
		const Kokkos::View< int ** > *	mmax_f = `nullptr`
	)

static

Transform radial B-spline surfaces to packed Fourier coefficients.

Parameters

[in]	bspl_data	Real coefficients `[s][chi][phi]`.
[out]	fft_data	Packed complex coefficients `[equation][phi mode]`.
[in]	ns	Number of radial surfaces.
[in]	nchi	Requested poloidal transform extent.
[in]	nphi	Requested toroidal transform extent.
[in]	neq_f	Number of packed radial/poloidal equations; each surface receives `neq_f/ns` consecutive poloidal slots.
[in]	filter	Optional integer multiplier `[phi][s][wrapped m]`; zero suppresses a mode.
[in]	fftminv	Optional per-phi multiplier, applied only with `filter`.
[in]	mmin_f	Optional first retained poloidal-mode metadata `[s][phi]`.
[in]	mmax_f	Must accompany `mmin_f` to enable mode-selected packing; currently retained for interface parity, while packed width is determined by `neq_f/ns`.

The forward coefficients include 1/(nchi_fft*nphi_fft) normalization. Active extents may be reduced to the supplied metadata/filter extents.

Referenced by orb5x::bspl2fft_3d().

◆ cached_plan_count_2d_backward()

static std::size_t orb5x::FFTWrapper::cached_plan_count_2d_backward ( )

static

Inspect the number of cached backward 2-D transform sizes.

Returns: Thread-safe cache entry count for regression/support diagnostics.

◆ cached_plan_count_2d_forward()

static std::size_t orb5x::FFTWrapper::cached_plan_count_2d_forward ( )

static

Inspect the number of cached forward 2-D transform sizes.

Returns: Thread-safe cache entry count for regression/support diagnostics.

◆ copy_complex_from_fftw()

static void orb5x::FFTWrapper::copy_complex_from_fftw	(	fftw_complex *	fftw_data,
		const Kokkos::View< Complex ** > &	kokkos_data,
		int	neq_f,
		int	nphi
	)

static

Copy FFTW host storage into a packed complex Kokkos View.

Parameters

[in]	fftw_data	Source of at least `neq_f*nphi` values.
[out]	kokkos_data	Destination `[equation][phi]`.
[in]	neq_f	Equation extent.
[in]	nphi	Toroidal extent and fastest flattened index.

◆ copy_complex_to_fftw()

static void orb5x::FFTWrapper::copy_complex_to_fftw	(	const Kokkos::View< Complex ** > &	kokkos_data,
		fftw_complex *	fftw_data,
		int	neq_f,
		int	nphi
	)

static

Copy a packed complex Kokkos View to FFTW host storage.

Parameters

[in]	kokkos_data	Source `[equation][phi]`.
[out]	fftw_data	Destination of at least `neq_f*nphi` values.
[in]	neq_f	Equation extent.
[in]	nphi	Toroidal extent and fastest flattened index.

◆ copy_from_fftw()

static void orb5x::FFTWrapper::copy_from_fftw	(	fftw_complex *	fftw_data,
		const Kokkos::View< Real *** > &	kokkos_data,
		int	ns,
		int	nchi,
		int	nphi
	)

static

Copy real components from FFTW storage into a 3-D Kokkos View.

Parameters

[in]	fftw_data	Source of `nsnchinphi` complex values.
[out]	kokkos_data	Destination `[s][chi][phi]`.
[in]	ns	Radial extent.
[in]	nchi	Poloidal extent.
[in]	nphi	Toroidal extent and fastest flattened index.

◆ copy_to_fftw()

static void orb5x::FFTWrapper::copy_to_fftw	(	const Kokkos::View< Real *** > &	kokkos_data,
		fftw_complex *	fftw_data,
		int	ns,
		int	nchi,
		int	nphi
	)

static

Copy a real 3-D Kokkos View to complex FFTW host storage.

Parameters

[in]	kokkos_data	Source `[s][chi][phi]`.
[out]	fftw_data	Destination of at least `nsnchinphi` values; the imaginary component is set to zero.
[in]	ns	Radial extent.
[in]	nchi	Poloidal extent.
[in]	nphi	Toroidal extent and fastest flattened index.

◆ destroy_plan()

static void orb5x::FFTWrapper::destroy_plan ( fftw_plan plan )

static

Destroy a caller-owned FFTW plan when non-null.

Parameters

[in] plan Plan to release; cached internal plans must not be passed.

Referenced by orb5x::destroy_plan().

◆ execute_backward()

static void orb5x::FFTWrapper::execute_backward ( fftw_plan plan )

static

Execute a previously created FFTW backward plan.

Parameters

[in] plan Valid plan still bound to live planning buffers.

Referenced by orb5x::execute_backward().

◆ execute_forward()

static void orb5x::FFTWrapper::execute_forward ( fftw_plan plan )

static

Execute a previously created FFTW forward plan.

Parameters

[in] plan Valid plan still bound to live planning buffers.

Referenced by orb5x::execute_forward().

◆ fft2bspl_2d()

static void orb5x::FFTWrapper::fft2bspl_2d	(	const Kokkos::View< Complex ** > &	fft_data,
		Kokkos::View< Real ** > &	bspl_data,
		int	nchi,
		int	nphi
	)

static

Compute the normalized real inverse of a full 2-D spectrum.

Parameters

[in]	fft_data	Complex spectrum `[chi mode][phi mode]`.
[out]	bspl_data	Real part of the inverse `[chi][phi]`.
[in]	nchi	Poloidal extent.
[in]	nphi	Toroidal extent.

Note: Applies 1/(nchi*nphi) after FFTW's unnormalized backward transform.

Referenced by orb5x::fft2bspl_2d().

◆ fft2bspl_3d()

static void orb5x::FFTWrapper::fft2bspl_3d	(	const Kokkos::View< Complex ** > &	fft_data,
		Kokkos::View< Real *** > &	bspl_data,
		int	ns,
		int	nchi,
		int	nphi,
		int	neq_f,
		const Kokkos::View< int ** > *	mmin_f = `nullptr`,
		const Kokkos::View< int ** > *	mmax_f = `nullptr`,
		bool	reconstruct_hermitian_toroidal = `false`,
		const char *	trace_tag = `nullptr`
	)

static

Reconstruct real B-spline surfaces from packed Fourier modes.

Parameters

[in]	fft_data	Packed coefficients `[equation][phi mode]` produced by bspl2fft_3d() or an equivalent solver.
[out]	bspl_data	Real output `[s][chi][phi]`; untouched extents are zero.
[in]	ns	Number of radial surfaces.
[in]	nchi	Poloidal inverse-transform extent.
[in]	nphi	Toroidal inverse-transform extent.
[in]	neq_f	Packed equation count.
[in]	mmin_f	Optional first poloidal mode `[s][phi]`.
[in]	mmax_f	Companion metadata enabling selected-mode unpacking; currently not used to set the packed width.
[in]	reconstruct_hermitian_toroidal	If true and the full toroidal extent is active, fill negative `(m,n)` modes by complex conjugacy so the inverse represents a real field.
[in]	trace_tag	Optional label enabling pre/post reconstruction traces for radial surface zero.

No scale is applied after FFTW's backward transform because the matching 3-D forward routine already applies the reciprocal transform size.

Referenced by orb5x::fft2bspl_3d().

◆ init_1d_backward()

static void orb5x::FFTWrapper::init_1d_backward	(	int	n,
		fftw_plan &	plan_backward,
		fftw_complex *	in,
		fftw_complex *	out
	)

static

Create an unnormalized 1-D backward complex FFTW plan.

Parameters

[in]	n	Transform length.
[out]	plan_backward	Newly allocated plan owned by the caller.
[in,out]	in	Planning/execution input buffer of at least `n` values.
[out]	out	Planning/execution output buffer of at least `n` values.

Referenced by orb5x::init_1d_backward().

◆ init_1d_forward()

static void orb5x::FFTWrapper::init_1d_forward	(	int	n,
		fftw_plan &	plan_forward,
		fftw_complex *	in,
		fftw_complex *	out
	)

static

Create an unnormalized 1-D forward complex FFTW plan.

Parameters

[in]	n	Transform length.
[out]	plan_forward	Newly allocated plan owned by the caller.
[in,out]	in	Planning/execution input buffer of at least `n` values.
[out]	out	Planning/execution output buffer of at least `n` values.

Referenced by orb5x::init_1d_forward().

◆ init_2d_backward()

static void orb5x::FFTWrapper::init_2d_backward	(	int	nchi,
		int	nphi,
		fftw_plan &	plan_backward,
		fftw_complex *	in,
		fftw_complex *	out
	)

static

Create an unnormalized backward FFT over (chi,phi).

Parameters

[in]	nchi	Poloidal transform length.
[in]	nphi	Toroidal transform length and fastest flattened dimension.
[out]	plan_backward	Newly allocated plan owned by the caller.
[in,out]	in	Buffer of at least `nchi*nphi` complex values.
[out]	out	Buffer of at least `nchi*nphi` complex values.

Referenced by orb5x::init_2d_backward().

◆ init_2d_forward()

static void orb5x::FFTWrapper::init_2d_forward	(	int	nchi,
		int	nphi,
		fftw_plan &	plan_forward,
		fftw_complex *	in,
		fftw_complex *	out
	)

static

Create an unnormalized forward FFT over (chi,phi).

Parameters

[in]	nchi	Poloidal transform length.
[in]	nphi	Toroidal transform length and fastest flattened dimension.
[out]	plan_forward	Newly allocated plan owned by the caller.
[in,out]	in	Buffer of at least `nchi*nphi` complex values.
[out]	out	Buffer of at least `nchi*nphi` complex values.

Referenced by orb5x::init_2d_forward().

The documentation for this class was generated from the following file:

fft_wrapper.hpp

Static Public Member Functions

Detailed Description

Member Function Documentation

◆ bspl2fft_2d()

◆ bspl2fft_3d()

◆ cached_plan_count_2d_backward()

◆ cached_plan_count_2d_forward()

◆ copy_complex_from_fftw()

◆ copy_complex_to_fftw()

◆ copy_from_fftw()

◆ copy_to_fftw()

◆ destroy_plan()

◆ execute_backward()

◆ execute_forward()

◆ fft2bspl_2d()

◆ fft2bspl_3d()

◆ init_1d_backward()

◆ init_1d_forward()

◆ init_2d_backward()

◆ init_2d_forward()