choose.hpp

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#pragma once
 
#include <cstddef>
 
#include <sycl/sycl.hpp>
 
#include "kernels/dpctl_tensor_types.hpp"
#include "utils/strided_iters.hpp"
 
namespace dpnp::kernels::choose
{
using dpctl::tensor::ssize_t;
 
template <typename ProjectorT,
          typename IndOutIndexerT,
          typename ChoicesIndexerT,
          typename IndT,
          typename T>
class ChooseFunctor
{
private:
    const IndT *ind = nullptr;
    T *dst = nullptr;
    char **chcs = nullptr;
    ssize_t n_chcs;
    const IndOutIndexerT ind_out_indexer;
    const ChoicesIndexerT chcs_indexer;
 
public:
    ChooseFunctor(const IndT *ind_,
                  T *dst_,
                  char **chcs_,
                  ssize_t n_chcs_,
                  const IndOutIndexerT &ind_out_indexer_,
                  const ChoicesIndexerT &chcs_indexer_)
        : ind(ind_), dst(dst_), chcs(chcs_), n_chcs(n_chcs_),
          ind_out_indexer(ind_out_indexer_), chcs_indexer(chcs_indexer_)
    {
    }
 
    void operator()(sycl::id<1> id) const
    {
        const ProjectorT proj{};
 
        ssize_t i = id[0];
 
        auto ind_dst_offsets = ind_out_indexer(i);
        ssize_t ind_offset = ind_dst_offsets.get_first_offset();
        ssize_t dst_offset = ind_dst_offsets.get_second_offset();
 
        IndT chc_idx = ind[ind_offset];
        // proj produces an index in the range of n_chcs
        ssize_t projected_idx = proj(n_chcs, chc_idx);
 
        ssize_t chc_offset = chcs_indexer(i, projected_idx);
 
        T *chc = reinterpret_cast<T *>(chcs[projected_idx]);
 
        dst[dst_offset] = chc[chc_offset];
    }
};
 
namespace strides
{
using dpctl::tensor::strides::CIndexer_vector;
 
struct NthStrideOffsetUnpacked
{
    NthStrideOffsetUnpacked(int common_nd,
                            ssize_t const *_offsets,
                            ssize_t const *_shape,
                            ssize_t const *_strides)
        : _ind(common_nd), nd(common_nd), offsets(_offsets), shape(_shape),
          strides(_strides)
    {
    }
 
    template <typename nT>
    size_t operator()(ssize_t gid, nT n) const
    {
        ssize_t relative_offset(0);
        _ind.get_displacement<const ssize_t *, const ssize_t *>(
            gid, shape, strides + (n * nd), relative_offset);
 
        return relative_offset + offsets[n];
    }
 
private:
    CIndexer_vector<ssize_t> _ind;
 
    int nd;
    ssize_t const *offsets;
    ssize_t const *shape;
    ssize_t const *strides;
};
 
static_assert(sycl::is_device_copyable_v<NthStrideOffsetUnpacked>);
 
} // namespace strides
} // namespace dpnp::kernels::choose