cuda_toolkit/include/cub/detail/choose_offset.cuh

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#pragma once

#include <cub/config.cuh>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header


#include <cuda/std/iterator>
#include <cuda/std/type_traits>

#include <cstdint>

CUB_NAMESPACE_BEGIN

namespace detail
{

/**
 * ChooseOffsetT checks NumItemsT, the type of the num_items parameter, and
 * selects the offset type based on it.
 */
template <typename NumItemsT>
struct ChooseOffsetT
{
  // NumItemsT must be an integral type (but not bool).
  static_assert(std::is_integral<NumItemsT>::value &&
                  !std::is_same<typename std::remove_cv<NumItemsT>::type, bool>::value,
                "NumItemsT must be an integral type, but not bool");

  // Unsigned integer type for global offsets.
  using Type =
    typename std::conditional<sizeof(NumItemsT) <= 4, std::uint32_t, unsigned long long>::type;
};

/**
 * common_iterator_value sets member type to the common_type of
 * value_type for all argument types. used to get OffsetT in
 * DeviceSegmentedReduce.
 */
template <typename... Iter>
struct common_iterator_value
{
  using type = ::cuda::std::__common_type_t<::cuda::std::__iter_value_type<Iter>...>;
};
template <typename... Iter>
using common_iterator_value_t = typename common_iterator_value<Iter...>::type;

} // namespace detail

CUB_NAMESPACE_END