shift_vect_converter.hpp

/*
 * shift_vect_converter.hpp
 *
 *  Created on: Feb 8, 2018
 *      Author: i-bird
 */

#ifndef SRC_DECOMPOSITION_SHIFT_VECT_CONVERTER_HPP_
#define SRC_DECOMPOSITION_SHIFT_VECT_CONVERTER_HPP_

#include "Space/Shape/HyperCube.hpp"

template<unsigned int dim, typename T>
class shift_vect_converter
{
    size_t red_shift_v[dim];

    // indexes
    size_t tmp[dim];

    // Dimension
    int dim_r = 0;

    void generateShiftVectors_ld(const Box<dim,T> & domain, size_t (& bc)[dim], openfpm::vector<Point<dim,T>> & shifts)
    {
        shifts.resize(openfpm::math::pow(3,dim));

        HyperCube<dim> hyp;

        for (long int i = dim-1 ; i >= 0 ; i--)
        {
            std::vector<comb<dim>> cmbs = hyp.getCombinations_R(i);

            for (size_t j = 0 ; j < cmbs.size() ; j++)
            {
                for (size_t k = 0 ; k < dim ; k++)
                {
                    switch (cmbs[j][k])
                    {
                    case 1:
                        shifts.get(cmbs[j].lin()).template get<0>()[k] = -(domain.getHigh(k) - domain.getLow(k));
                        break;
                    case 0:
                        shifts.get(cmbs[j].lin()).template get<0>()[k] = 0;
                        break;
                    case -1:
                        shifts.get(cmbs[j].lin()).template get<0>()[k] = (domain.getHigh(k) - domain.getLow(k));
                        break;
                    }
                }
            }
        }
    }

    void generateShiftVectors_hd(const Box<dim,T> & domain, size_t (& bc)[dim], openfpm::vector<Point<dim,T>> & shifts)
    {
        // get the indexes of the free degree of freedom
        for (size_t i = 0 ; i < dim ; i++)
        {
            if (bc[i] == PERIODIC)
            {
                red_shift_v[dim_r] = i;
                dim_r++;
            }
        }

        HyperCube<dim> hyp;

        // precalculate the nuber of shift vectors
        size_t nsv = 0;
        for (long int i = dim-1 ; i >= 0 ; i--)
        {nsv += hyp.getCombinations_R_bc(i,bc).size();}
        shifts.resize(nsv+1);

        for (long int i = dim-1 ; i >= 0 ; i--)
        {
            std::vector<comb<dim>> cmbs = hyp.getCombinations_R_bc(i,bc);

            for (size_t j = 0 ; j < cmbs.size() ; j++)
            {
                size_t lin_cmb = linId_hd(cmbs[j]);

                for (size_t k = 0 ; k < dim ; k++)
                {
                    switch (cmbs[j][k])
                    {
                    case 1:
                        shifts.get(lin_cmb).template get<0>()[k] = -(domain.getHigh(k) - domain.getLow(k));
                        break;
                    case 0:
                        shifts.get(lin_cmb).template get<0>()[k] = 0;
                        break;
                    case -1:
                        shifts.get(lin_cmb).template get<0>()[k] = (domain.getHigh(k) - domain.getLow(k));
                        break;
                    }
                }
            }
        }
    }

public:

    void generateShiftVectors(const Box<dim,T> & domain, size_t (& bc)[dim], openfpm::vector<Point<dim,T>> & shifts)
    {
        if (dim < 10)
        {generateShiftVectors_ld(domain,bc,shifts);}
        else
        {generateShiftVectors_hd(domain,bc,shifts);}
    }

    void Initialize(size_t (& bc)[dim])
    {
        // get the indexes of the free degree of freedom
        for (size_t i = 0 ; i < dim ; i++)
        {
            if (bc[i] == PERIODIC)
            {
                red_shift_v[dim] = i;
                dim_r++;
            }
        }
    }

    size_t linId_hd(const comb<dim> & cmb)
    {
        size_t cul = 1;
        size_t lin = 0;
        for (long int i = 0 ; i < dim_r ; i++)
        {
            lin += cul*(cmb.c[red_shift_v[i]] + 1);
            cul *= 3;
        }

        return lin;
    }

    inline size_t linId_ld(const comb<dim> & cmb)
    {
        return cmb.lin();
    }

    inline size_t linId(const comb<dim> & cmb)
    {
        if (dim < 10)
        {return linId_ld(cmb);}

        return linId_hd(cmb);
    }

};


#endif /* SRC_DECOMPOSITION_SHIFT_VECT_CONVERTER_HPP_ */