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#include <SpectralFieldData.H>
using namespace amrex;
SpectralFieldData::SpectralFieldData( const BoxArray& realspace_ba,
const SpectralKSpace& k_space,
const DistributionMapping& dm )
{
const BoxArray& spectralspace_ba = k_space.spectralspace_ba;
// Allocate the arrays that contain the fields in spectral space
Ex = SpectralField(spectralspace_ba, dm, 1, 0);
Ey = SpectralField(spectralspace_ba, dm, 1, 0);
Ez = SpectralField(spectralspace_ba, dm, 1, 0);
Bx = SpectralField(spectralspace_ba, dm, 1, 0);
By = SpectralField(spectralspace_ba, dm, 1, 0);
Bz = SpectralField(spectralspace_ba, dm, 1, 0);
Jx = SpectralField(spectralspace_ba, dm, 1, 0);
Jy = SpectralField(spectralspace_ba, dm, 1, 0);
Jz = SpectralField(spectralspace_ba, dm, 1, 0);
rho_old = SpectralField(spectralspace_ba, dm, 1, 0);
rho_new = SpectralField(spectralspace_ba, dm, 1, 0);
// Allocate temporary arrays - over different boxarrays
tmpRealField = SpectralField(realspace_ba, dm, 1, 0);
tmpSpectralField = SpectralField(spectralspace_ba, dm, 1, 0);
// Allocate the coefficients that allow to shift between nodal and cell-centered
xshift_C2N = k_space.getSpectralShiftFactor(dm, 0, ShiftType::CenteredToNodal);
xshift_N2C = k_space.getSpectralShiftFactor(dm, 0, ShiftType::NodalToCentered);
#if (AMREX_SPACEDIM == 3)
yshift_C2N = k_space.getSpectralShiftFactor(dm, 1, ShiftType::CenteredToNodal);
yshift_N2C = k_space.getSpectralShiftFactor(dm, 1, ShiftType::NodalToCentered);
zshift_C2N = k_space.getSpectralShiftFactor(dm, 2, ShiftType::CenteredToNodal);
zshift_N2C = k_space.getSpectralShiftFactor(dm, 2, ShiftType::NodalToCentered);
#else
zshift_C2N = k_space.getSpectralShiftFactor(dm, 1, ShiftType::CenteredToNodal);
zshift_N2C = k_space.getSpectralShiftFactor(dm, 1, ShiftType::NodalToCentered);
#endif
// Allocate and initialize the FFT plans
forward_plan = FFTplans(spectralspace_ba, dm);
backward_plan = FFTplans(spectralspace_ba, dm);
for ( MFIter mfi(spectralspace_ba, dm); mfi.isValid(); ++mfi ){
Box bx = spectralspace_ba[mfi];
#ifdef AMREX_USE_GPU
// Add cuFFT-specific code
#else
// Create FFTW plans
forward_plan[mfi] =
#if (AMREX_SPACEDIM == 3) // Swap dimensions: AMReX data is Fortran-order, but FFTW is C-order
fftw_plan_dft_3d( bx.length(2), bx.length(1), bx.length(0),
#else
fftw_plan_dft_2d( bx.length(1), bx.length(0),
#endif
reinterpret_cast<fftw_complex*>( tmpRealField[mfi].dataPtr() ),
reinterpret_cast<fftw_complex*>( tmpSpectralField[mfi].dataPtr() ),
FFTW_FORWARD, FFTW_ESTIMATE );
backward_plan[mfi] =
#if (AMREX_SPACEDIM == 3) // Swap dimensions: AMReX data is Fortran-order, but FFTW is C-order
fftw_plan_dft_3d( bx.length(2), bx.length(1), bx.length(0),
#else
fftw_plan_dft_2d( bx.length(1), bx.length(0),
#endif
reinterpret_cast<fftw_complex*>( tmpSpectralField[mfi].dataPtr() ),
reinterpret_cast<fftw_complex*>( tmpRealField[mfi].dataPtr() ),
FFTW_BACKWARD, FFTW_ESTIMATE );
// TODO: Do real-to-complex transform instead of complex-to-complex
// TODO: Let the user decide whether to use FFTW_ESTIMATE or FFTW_MEASURE
#endif
}
}
SpectralFieldData::~SpectralFieldData()
{
if (tmpRealField.size() > 0){
for ( MFIter mfi(tmpRealField); mfi.isValid(); ++mfi ){
#ifdef AMREX_USE_GPU
// Add cuFFT-specific code
#else
// Destroy FFTW plans
fftw_destroy_plan( forward_plan[mfi] );
fftw_destroy_plan( backward_plan[mfi] );
#endif
}
}
}
/* TODO: Documentation
* Example: ForwardTransform( Efield_cp[0], SpectralFieldIndex::Ex )
*/
void
SpectralFieldData::ForwardTransform( const MultiFab& mf,
const int field_index, const int i_comp )
{
// Loop over boxes
for ( MFIter mfi(mf); mfi.isValid(); ++mfi ){
// Copy the real-space field `mf` to the temporary field `tmpRealField`
// This ensures that all fields have the same number of points
// before the Fourier transform.
// As a consequence, the copy discards the *last* point of `mf`
// in any direction that has *nodal* index type.
{
Box bx = mf[mfi].box();
const Box realspace_bx = bx.enclosedCells(); // discards last point in each nodal direction
AMREX_ALWAYS_ASSERT( realspace_bx == tmpRealField[mfi].box() );
Array4<const Real> mf_arr = mf[mfi].array();
Array4<Complex> tmp_arr = tmpRealField[mfi].array();
ParallelFor( realspace_bx,
[=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
tmp_arr(i,j,k) = mf_arr(i,j,k,i_comp);
});
}
// Perform Fourier transform from `tmpRealField` to `tmpSpectralField`
#ifdef AMREX_USE_GPU
// Add cuFFT-specific code ; make sure that this is done on the same
// GPU stream as the above copy
#else
fftw_execute( forward_plan[mfi] );
#endif
// Copy the spectral-space field `tmpSpectralField` to the appropriate field
// (specified by the input argument field_index )
{
SpectralField& field = getSpectralField( field_index );
Array4<Complex> field_arr = field[mfi].array();
Array4<const Complex> tmp_arr = tmpSpectralField[mfi].array();
const Box spectralspace_bx = tmpSpectralField[mfi].box();
ParallelFor( spectralspace_bx,
[=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
field_arr(i,j,k) = tmp_arr(i,j,k);
});
}
}
}
/* TODO: Documentation
*/
void
SpectralFieldData::BackwardTransform( MultiFab& mf,
const int field_index, const int i_comp )
{
// Check field index type, in order to apply proper shift in spectral space
const bool is_nodal_x = mf.is_nodal(0);
#if (AMREX_SPACEDIM == 3)
const bool is_nodal_y = mf.is_nodal(1);
const bool is_nodal_z = mf.is_nodal(2);
#else
const bool is_nodal_z = mf.is_nodal(1);
#endif
// Loop over boxes
for ( MFIter mfi(mf); mfi.isValid(); ++mfi ){
// Copy the appropriate field (specified by the input argument field_index)
// to the spectral-space field `tmpSpectralField`
{
SpectralField& field = getSpectralField( field_index );
Array4<const Complex> field_arr = field[mfi].array();
Array4<Complex> tmp_arr = tmpSpectralField[mfi].array();
const Complex* xshift_C2N_arr = xshift_C2N[mfi].dataPtr();
const Complex* yshift_C2N_arr = yshift_C2N[mfi].dataPtr();
const Complex* zshift_C2N_arr = zshift_C2N[mfi].dataPtr();
// Loop over indices within one box
const Box spectralspace_bx = tmpSpectralField[mfi].box();
ParallelFor( spectralspace_bx,
[=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
Complex spectral_field_value = field_arr(i,j,k);
// Apply proper shift in each dimension
if (is_nodal_x==false) spectral_field_value *= xshift_C2N_arr[i];
#if (AMREX_SPACEDIM == 3)
if (is_nodal_y==false) spectral_field_value *= yshift_C2N_arr[j];
#endif
if (is_nodal_z==false) spectral_field_value *= zshift_C2N_arr[k];
// Copy field into temporary array
tmp_arr(i,j,k) = spectral_field_value;
});
}
// Perform Fourier transform from `tmpSpectralField` to `tmpRealField`
#ifdef AMREX_USE_GPU
// Add cuFFT-specific code ; make sure that this is done on the same
// GPU stream as the above copy
#else
fftw_execute( backward_plan[mfi] );
#endif
// Copy the temporary field `tmpRealField` to the real-space field `mf`
// The copy does *not* fill the *last* point of `mf`
// in any direction that has *nodal* index type (but this point is
// in the guard cells and will be filled by guard cell exchange)
// Normalize (divide by 1/N) since the FFT result in a factor N
{
Box bx = mf[mfi].box();
const Box realspace_bx = bx.enclosedCells();
// `enclosedells` discards last point in each nodal direction
AMREX_ALWAYS_ASSERT( realspace_bx == tmpRealField[mfi].box() );
Array4<Real> mf_arr = mf[mfi].array();
Array4<const Complex> tmp_arr = tmpRealField[mfi].array();
// For normalization: divide by the number of points in the box
const Real inv_N = 1./bx.numPts();
ParallelFor( realspace_bx,
[=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept {
mf_arr(i,j,k,i_comp) = inv_N*tmp_arr(i,j,k).real();
});
}
}
}
SpectralField&
SpectralFieldData::getSpectralField( const int field_index )
{
switch(field_index)
{
case SpectralFieldIndex::Ex : return Ex; break;
case SpectralFieldIndex::Ey : return Ey; break;
case SpectralFieldIndex::Ez : return Ez; break;
case SpectralFieldIndex::Bx : return Bx; break;
case SpectralFieldIndex::By : return By; break;
case SpectralFieldIndex::Bz : return Bz; break;
case SpectralFieldIndex::Jx : return Jx; break;
case SpectralFieldIndex::Jy : return Jy; break;
case SpectralFieldIndex::Jz : return Jz; break;
case SpectralFieldIndex::rho_old : return rho_old; break;
case SpectralFieldIndex::rho_new : return rho_new; break;
default : return tmpSpectralField; // For synthax; should not occur in practice
}
}
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