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muSpectre/src/fft/fftw_engine.cc
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fftw_engine.cc
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/**
* @file fftw_engine.cc
*
* @author Till Junge <till.junge@altermail.ch>
*
* @date 03 Dec 2017
*
* @brief implements the fftw engine
*
* Copyright © 2017 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µSpectre is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "common/ccoord_operations.hh"
#include "fft/fftw_engine.hh"
namespace muSpectre {
template <Dim_t DimS, Dim_t DimM>
FFTWEngine<DimS, DimM>::FFTWEngine(Ccoord resolutions, Communicator comm)
:Parent{resolutions, comm}
{
for (auto && pixel: CcoordOps::Pixels<DimS>(this->fourier_resolutions)) {
this->work_space_container.add_pixel(pixel);
}
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void FFTWEngine<DimS, DimM>::initialise(FFT_PlanFlags plan_flags) {
if (this->initialised) {
throw std::runtime_error("double initialisation, will leak memory");
}
Parent::initialise(plan_flags);
const int & rank = DimS;
std::array<int, DimS> narr;
const int * const n = &narr[0];
std::copy(this->subdomain_resolutions.begin(),
this->subdomain_resolutions.end(),
narr.begin());
int howmany = Field_t::nb_components;
//temporary buffer for plan
size_t alloc_size = (CcoordOps::get_size(this->subdomain_resolutions)*
howmany);
Real * r_work_space = fftw_alloc_real(alloc_size);
Real * in = r_work_space;
const int * const inembed = nullptr;//nembed are tricky: they refer to physical layout
int istride = howmany;
int idist = 1;
fftw_complex * out = reinterpret_cast<fftw_complex*>(this->work.data());
const int * const onembed = nullptr;
int ostride = howmany;
int odist = idist;
unsigned int flags;
switch (plan_flags) {
case FFT_PlanFlags::estimate: {
flags = FFTW_ESTIMATE;
break;
}
case FFT_PlanFlags::measure: {
flags = FFTW_MEASURE;
break;
}
case FFT_PlanFlags::patient: {
flags = FFTW_PATIENT;
break;
}
default:
throw std::runtime_error("unknown planner flag type");
break;
}
this->plan_fft = fftw_plan_many_dft_r2c(rank, n, howmany, in, inembed, istride,
idist, out, onembed, ostride, odist,
FFTW_PRESERVE_INPUT | flags);
if (this->plan_fft == nullptr) {
throw std::runtime_error("Plan failed");
}
fftw_complex * i_in = reinterpret_cast<fftw_complex*>(this->work.data());
Real * i_out = r_work_space;
this->plan_ifft = fftw_plan_many_dft_c2r(rank, n, howmany, i_in, inembed,
istride, idist, i_out, onembed,
ostride, odist, flags);
if (this->plan_ifft == nullptr) {
throw std::runtime_error("Plan failed");
}
fftw_free(r_work_space);
this->initialised = true;
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
FFTWEngine<DimS, DimM>::~FFTWEngine<DimS, DimM>() noexcept {
fftw_destroy_plan(this->plan_fft);
fftw_destroy_plan(this->plan_ifft);
// TODO: We cannot run fftw_cleanup since subsequent FFTW calls will fail
// but multiple FFT engines can be active at the same time.
//fftw_cleanup();
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
typename FFTWEngine<DimS, DimM>::Workspace_t &
FFTWEngine<DimS, DimM>::fft (Field_t & field) {
if (this->plan_fft == nullptr) {
throw std::runtime_error("fft plan not initialised");
}
if (field.size() != CcoordOps::get_size(this->subdomain_resolutions)) {
throw std::runtime_error("size mismatch");
}
fftw_execute_dft_r2c(this->plan_fft,
field.data(),
reinterpret_cast<fftw_complex*>(this->work.data()));
return this->work;
}
/* ---------------------------------------------------------------------- */
template <Dim_t DimS, Dim_t DimM>
void
FFTWEngine<DimS, DimM>::ifft (Field_t & field) const {
if (this->plan_ifft == nullptr) {
throw std::runtime_error("ifft plan not initialised");
}
if (field.size() != CcoordOps::get_size(this->subdomain_resolutions)) {
throw std::runtime_error("size mismatch");
}
fftw_execute_dft_c2r(this->plan_ifft,
reinterpret_cast<fftw_complex*>(this->work.data()),
field.data());
}
template class FFTWEngine<twoD, twoD>;
template class FFTWEngine<twoD, threeD>;
template class FFTWEngine<threeD, threeD>;
} // muSpectre
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