linear_interpolation_1D.hh

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#pragma once
 
// DiFfRG
#include <DiFfRG/common/cuda_prefix.hh>
#include <DiFfRG/common/math.hh>
#include <DiFfRG/physics/interpolation/common.hh>
 
// standard library
#include <memory>
 
// external libraries
#include <autodiff/forward/real.hpp>
 
namespace DiFfRG
{
  template <typename NT, typename Coordinates> class LinearInterpolator1D
  {
    static_assert(Coordinates::dim == 1, "LinearInterpolator1D requires 1D coordinates");
 
  public:
    LinearInterpolator1D(const std::vector<NT> &data, const Coordinates &coordinates);
    LinearInterpolator1D(const NT *data, const Coordinates &coordinates);
    LinearInterpolator1D(const Coordinates &coordinates);
    LinearInterpolator1D(const LinearInterpolator1D &other);
 
    template <typename NT2> void update(const NT2 *data)
    {
      if (!owner) throw std::runtime_error("Cannot update data of non-owner interpolator");
 
      for (uint i = 0; i < size; ++i)
        m_data[i] = NT(data[i]);
 
      update();
    }
    void update();
 
    NT *data() const;
 
    __device__ __host__ NT operator()(const typename Coordinates::ctype x) const
    {
#ifndef __CUDA_ARCH__
      using std::ceil;
      using std::floor;
      using std::max;
      using std::min;
#endif
 
      auto idx = coordinates.backward(x);
      idx = max(static_cast<decltype(idx)>(0), min(idx, static_cast<decltype(idx)>(size - 1)));
#ifndef __CUDA_ARCH__
      return m_data[uint(floor(idx))] * (NT(1) - idx + floor(idx)) + m_data[uint(ceil(idx))] * (idx - floor(idx));
#else
      return device_data_ptr[uint(floor(idx))] * (NT(1) - idx + floor(idx)) +
             device_data_ptr[uint(ceil(idx))] * (idx - floor(idx));
#endif
    }
 
    NT &operator[](const uint i);
    const NT &operator[](const uint i) const;
 
    const Coordinates &get_coordinates() const { return coordinates; }
 
  private:
    const uint size;
    const Coordinates coordinates;
 
    std::shared_ptr<NT[]> m_data;
    std::shared_ptr<thrust::device_vector<NT>> device_data;
    const NT *device_data_ptr;
 
    const bool owner;
  };
} // namespace DiFfRG