linear_weights.hpp

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#ifndef LINEAR_WEIGHTS_HPP
#define LINEAR_WEIGHTS_HPP

#include "simd.hpp"
#include "globals.hpp"

// A convenient struct for the many times a linear weight needs to be calculated and stored
struct LinearWeights{
    int i;             // the lower index
    double w[2];       // the weights of i and i+1

    KOKKOS_INLINE_FUNCTION LinearWeights(){}

    // Allow set in the constructor for legibility
    KOKKOS_INLINE_FUNCTION LinearWeights(double var, double inv_d ){
        set(var, inv_d);
    }

    KOKKOS_INLINE_FUNCTION LinearWeights(double var, double inv_d, int i_max ){
        set(var, inv_d, i_max);
    }

    // Calculate the weights
    KOKKOS_INLINE_FUNCTION void set(double var, double inv_d ){
        double var_over_d = var*inv_d;
        i = floor(var_over_d);

        w[1] = var_over_d - i;
        w[0] = 1.0 - w[1];
    }

    // Calculate the weights with a max index to be safe
    // This check shouldnt be necessary and it gives buggy weights if caught
    KOKKOS_INLINE_FUNCTION void set(double var, double inv_d, int i_max){
        double var_over_d = var*inv_d;
        i = floor(var_over_d);

        i = min(i,i_max-1);
        w[1] = min(1.0,var_over_d - i);
        w[0] = 1.0 - w[1];
    }

};


struct SimdLinearWeights{
    Simd<int> i;             // the lower index
    Simd<double> w[2];       // the weights of i and i+1

    KOKKOS_INLINE_FUNCTION SimdLinearWeights(){}

    // Allow set in the constructor for legibility
    KOKKOS_INLINE_FUNCTION SimdLinearWeights(Simd<double> var, double inv_d ){
        set(var, inv_d);
    }

    KOKKOS_INLINE_FUNCTION SimdLinearWeights(Simd<double> var, double inv_d, int i_max ){
        set(var, inv_d, i_max);
    }

    // Calculate the weights
    KOKKOS_INLINE_FUNCTION void set(Simd<double> var, double inv_d ){
        for(int i_simd = 0; i_simd<SIMD_SIZE; i_simd++){
            double var_over_d = var[i_simd]*inv_d;
            i[i_simd] = floor(var_over_d);

            w[1][i_simd] = var_over_d - i[i_simd];
            w[0][i_simd] = 1.0 - w[1][i_simd];
        }
    }

    // Calculate the weights with a max index to be safe
    // This check shouldnt be necessary and it gives buggy weights if caught
    KOKKOS_INLINE_FUNCTION void set(Simd<double> var, double inv_d, int i_max){
        for(int i_simd = 0; i_simd<SIMD_SIZE; i_simd++){
            double var_over_d = var[i_simd]*inv_d;
            i[i_simd] = floor(var_over_d);

            i[i_simd] = min(i[i_simd],i_max-1);
            w[1][i_simd] = min(1.0,var_over_d - i[i_simd]);
            w[0][i_simd] = 1.0 - w[1][i_simd];
        }
    }

};


#endif