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muSpectre/src/libmugrid/ccoord_operations.hh
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ccoord_operations.hh
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/**
* @file ccoord_operations.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 29 Sep 2017
*
* @brief common operations on pixel addressing
*
* Copyright © 2017 Till Junge
*
* µGrid is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µGrid 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 Lesser General Public License
* along with µGrid; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* * Boston, MA 02111-1307, USA.
*
* Additional permission under GNU GPL version 3 section 7
*
* If you modify this Program, or any covered work, by linking or combining it
* with proprietary FFT implementations or numerical libraries, containing parts
* covered by the terms of those libraries' licenses, the licensors of this
* Program grant you additional permission to convey the resulting work.
*/
#include <functional>
#include <numeric>
#include <utility>
#include <vector>
#include <Eigen/Dense>
#include "grid_common.hh"
#include "iterators.hh"
#ifndef SRC_COMMON_CCOORD_OPERATIONS_HH_
#define SRC_COMMON_CCOORD_OPERATIONS_HH_
namespace muGrid {
namespace CcoordOps {
namespace internal {
//! simple helper returning the first argument and ignoring the second
template <typename T>
constexpr T ret(T val, size_t /*dummy*/) {
return val;
}
//! helper to build cubes
template <Dim_t Dim, typename T, size_t... I>
constexpr std::array<T, Dim> cube_fun(T val, std::index_sequence<I...>) {
return std::array<T, Dim>{ret(val, I)...};
}
//! computes hermitian size according to FFTW
template <Dim_t Dim, size_t... I>
constexpr Ccoord_t<Dim> herm(const Ccoord_t<Dim> & full_sizes,
std::index_sequence<I...>) {
return Ccoord_t<Dim>{full_sizes[I]..., full_sizes.back() / 2 + 1};
}
//! compute the stride in a direction of a row-major grid
template <Dim_t Dim>
constexpr Dim_t stride(const Ccoord_t<Dim> & sizes, const size_t index) {
static_assert(Dim > 0, "only for positive numbers of dimensions");
auto const diff{Dim - 1 - Dim_t(index)};
Dim_t ret_val{1};
for (Dim_t i{0}; i < diff; ++i) {
ret_val *= sizes[Dim - 1 - i];
}
return ret_val;
}
//! get all strides from a row-major grid (helper function)
template <Dim_t Dim, size_t... I>
constexpr Ccoord_t<Dim> compute_strides(const Ccoord_t<Dim> & sizes,
std::index_sequence<I...>) {
return Ccoord_t<Dim>{stride<Dim>(sizes, I)...};
}
} // namespace internal
//-----------------------------------------------------------------------//
//! returns a grid of equal resolutions in each direction
template <size_t dim, typename T>
constexpr std::array<T, dim> get_cube(T size) {
return internal::cube_fun<dim>(size, std::make_index_sequence<dim>{});
}
/* ---------------------------------------------------------------------- */
//! returns the hermition grid to correcsponding to a full grid
template <size_t dim>
constexpr Ccoord_t<dim> get_hermitian_sizes(Ccoord_t<dim> full_sizes) {
return internal::herm<dim>(full_sizes,
std::make_index_sequence<dim - 1>{});
}
//! return physical vector of a cell of cubic pixels
template <size_t dim>
Eigen::Matrix<Real, dim, 1> get_vector(const Ccoord_t<dim> & ccoord,
Real pix_size = 1.) {
Eigen::Matrix<Real, dim, 1> retval;
for (size_t i = 0; i < dim; ++i) {
retval[i] = pix_size * ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! return physical vector of a cell of general pixels
template <size_t dim, typename T>
Eigen::Matrix<T, dim, 1>
get_vector(const Ccoord_t<dim> & ccoord,
Eigen::Matrix<T, Dim_t(dim), 1> pix_size) {
Eigen::Matrix<T, dim, 1> retval = pix_size;
for (size_t i = 0; i < dim; ++i) {
retval[i] *= ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! return physical vector of a cell of general pixels
template <size_t dim, typename T>
Eigen::Matrix<T, dim, 1> get_vector(const Ccoord_t<dim> & ccoord,
const std::array<T, dim> & pix_size) {
Eigen::Matrix<T, dim, 1> retval{};
for (size_t i = 0; i < dim; ++i) {
retval[i] = pix_size[i] * ccoord[i];
}
return retval;
}
/* ---------------------------------------------------------------------- */
//! get all strides from a row-major grid
template <size_t dim>
constexpr Ccoord_t<dim> get_default_strides(const Ccoord_t<dim> & sizes) {
return internal::compute_strides<dim>(sizes,
std::make_index_sequence<dim>{});
}
//----------------------------------------------------------------------------//
//! get the i-th pixel in a grid of size sizes
template <size_t dim>
constexpr Ccoord_t<dim> get_ccoord(const Ccoord_t<dim> & resolutions,
const Ccoord_t<dim> & locations,
Dim_t index) {
Ccoord_t<dim> retval{{0}};
Dim_t factor{1};
for (Dim_t i = dim - 1; i >= 0; --i) {
retval[i] = index / factor % resolutions[i] + locations[i];
if (i != 0) {
factor *= resolutions[i];
}
}
return retval;
}
//----------------------------------------------------------------------------//
//! get the i-th pixel in a grid of size sizes
template <size_t dim, size_t... I>
constexpr Ccoord_t<dim> get_ccoord(const Ccoord_t<dim> & resolutions,
const Ccoord_t<dim> & locations,
Dim_t index, std::index_sequence<I...>) {
Ccoord_t<dim> ccoord{get_ccoord<dim>(resolutions, locations, index)};
return Ccoord_t<dim>({ccoord[I]...});
}
//-----------------------------------------------------------------------//
//! get the linear index of a pixel in a given grid
template <size_t dim>
constexpr Dim_t get_index(const Ccoord_t<dim> & sizes,
const Ccoord_t<dim> & locations,
const Ccoord_t<dim> & ccoord) {
Dim_t retval{0};
Dim_t factor{1};
for (Dim_t i = dim - 1; i >= 0; --i) {
retval += (ccoord[i] - locations[i]) * factor;
if (i != 0) {
factor *= sizes[i];
}
}
return retval;
}
//-----------------------------------------------------------------------//
//! get the linear index of a pixel given a set of strides
template <size_t dim>
constexpr Dim_t get_index_from_strides(const Ccoord_t<dim> & strides,
const Ccoord_t<dim> & ccoord) {
Dim_t retval{0};
for (const auto & tup : akantu::zip(strides, ccoord)) {
const auto & stride = std::get<0>(tup);
const auto & ccord_ = std::get<1>(tup);
retval += stride * ccord_;
}
return retval;
}
//-----------------------------------------------------------------------//
//! get the number of pixels in a grid
template <size_t dim>
constexpr size_t get_size(const Ccoord_t<dim> & sizes) {
Dim_t retval{1};
for (size_t i = 0; i < dim; ++i) {
retval *= sizes[i];
}
return retval;
}
//-----------------------------------------------------------------------//
//! get the number of pixels in a grid given its strides
template <size_t dim>
constexpr size_t get_size_from_strides(const Ccoord_t<dim> & sizes,
const Ccoord_t<dim> & strides) {
return sizes[0] * strides[0];
}
/* ---------------------------------------------------------------------- */
/**
* centralises iterating over square (or cubic) discretisation
* grids. The optional parameter pack `dmap` can be used to
* specify the order of the axes in which to iterate over the
* dimensions (i.e., dmap = 0, 1, 2 is rowmajor, and 0, 2, 1 would
* be a custom order in which the second and third dimension are
* transposed
*/
template <size_t dim, int... dmap>
class Pixels {
public:
//! constructor
Pixels(const Ccoord_t<dim> & resolutions = Ccoord_t<dim>{},
const Ccoord_t<dim> & locations = Ccoord_t<dim>{})
: resolutions{resolutions}, locations{locations} {};
//! copy constructor
Pixels(const Pixels & other) = default;
//! assignment operator
Pixels & operator=(const Pixels & other) = default;
virtual ~Pixels() = default;
/**
* iterators over `Pixels` dereferences to cell coordinates
*/
class iterator {
public:
using value_type = Ccoord_t<dim>; //!< stl conformance
using const_value_type = const value_type; //!< stl conformance
using pointer = value_type *; //!< stl conformance
using difference_type = std::ptrdiff_t; //!< stl conformance
using iterator_category = std::forward_iterator_tag; //!< stl
//!< conformance
using reference = value_type; //!< stl conformance
//! constructor
explicit iterator(const Pixels & pixels, bool begin = true);
virtual ~iterator() = default;
//! dereferencing
inline value_type operator*() const;
//! pre-increment
inline iterator & operator++();
//! inequality
inline bool operator!=(const iterator & other) const;
//! equality
inline bool operator==(const iterator & other) const;
protected:
const Pixels & pixels; //!< ref to pixels in cell
size_t index; //!< index of currect pointed-to pixel
};
//! stl conformance
inline iterator begin() const { return iterator(*this); }
//! stl conformance
inline iterator end() const { return iterator(*this, false); }
//! stl conformance
inline size_t size() const { return get_size(this->resolutions); }
protected:
Ccoord_t<dim> resolutions; //!< resolutions of this domain
Ccoord_t<dim> locations; //!< locations of this domain
};
/* ---------------------------------------------------------------------- */
template <size_t dim, int... dmap>
Pixels<dim, dmap...>::iterator::iterator(const Pixels & pixels, bool begin)
: pixels{pixels}, index{begin ? 0 : get_size(pixels.resolutions)} {}
/* ---------------------------------------------------------------------- */
template <size_t dim, int... dmap>
typename Pixels<dim, dmap...>::iterator::value_type
Pixels<dim, dmap...>::iterator::operator*() const {
return get_ccoord(pixels.resolutions, pixels.locations, this->index,
std::conditional_t<sizeof...(dmap) == 0,
std::make_index_sequence<dim>,
std::index_sequence<dmap...>>{});
}
/* ---------------------------------------------------------------------- */
template <size_t dim, int... dmap>
bool Pixels<dim, dmap...>::iterator::
operator!=(const iterator & other) const {
return (this->index != other.index) || (&this->pixels != &other.pixels);
}
/* ---------------------------------------------------------------------- */
template <size_t dim, int... dmap>
bool Pixels<dim, dmap...>::iterator::
operator==(const iterator & other) const {
return !(*this != other);
}
/* ---------------------------------------------------------------------- */
template <size_t dim, int... dmap>
typename Pixels<dim, dmap...>::iterator & Pixels<dim, dmap...>::iterator::
operator++() {
++this->index;
return *this;
}
} // namespace CcoordOps
} // namespace muGrid
#endif // SRC_COMMON_CCOORD_OPERATIONS_HH_
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