Interp1d.icc

#include <cmath>
#include <type_traits>
 
namespace isce3 { namespace cuda { namespace core {
 
template<class Kernel, typename T>
CUDA_HOSTDEV inline T interp1d(const Kernel& kernel, const T* x, size_t length,
                               size_t stride, double t, bool periodic)
{
 
    auto width = static_cast<int>(std::ceil(kernel.width()));
    auto i0 = (width % 2 == 0) ? static_cast<long>(std::ceil(t))
                               : static_cast<long>(std::round(t));
 
    auto low = i0 - width / 2;
    auto high = low + width;
 
    if (not periodic and (low < 0 or high >= length)) {
        return T(0);
    }
 
    using U = typename std::common_type<typename Kernel::value_type, T>::type;
 
    U sum = 0.;
    for (auto i = low; i < high; ++i) {
        auto j = (periodic) ? i % length : i;
        double ti = static_cast<double>(i) - t;
        auto w = kernel(ti);
        sum += w * x[j * stride];
    }
 
    return static_cast<T>(sum);
}
 
}}} // namespace isce3::cuda::core