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/*! 
  \file
  \brief Defines an unsigned 256b integer.
*/

#pragma once
#include "cutlass/cutlass.h"
#if defined(__CUDACC_RTC__)
#include CUDA_STD_HEADER(cstdint)
#else
#include <cstdint>
#include <cstdlib>
#include <cmath>
#include <type_traits>
#include <stdexcept>
#endif
#include "cutlass/uint128.h"

namespace cutlass {

///! Unsigned 256b integer type
struct alignas(32) uint256_t {
  /// Size of one part of the uint's storage in bits
  static constexpr int storage_bits_ = 128;

  struct hilo {
    uint128_t lo;
    uint128_t hi;
  };

  // Use a union to store either low and high parts.
  union {
    struct hilo hilo_;
  };

  //
  // Methods
  //

  /// Default ctor
  CUTLASS_HOST_DEVICE
  uint256_t() : hilo_{uint128_t{}, uint128_t{}} {}

  /// Constructor from uint128
  CUTLASS_HOST_DEVICE
  uint256_t(uint128_t lo_) : hilo_{lo_, uint128_t{}} {}

  /// Constructor from two 128b unsigned integers
  CUTLASS_HOST_DEVICE
  uint256_t(uint128_t lo_, uint128_t hi_) : hilo_{lo_, hi_} {}

  /// Lossily cast to uint128_t
  CUTLASS_HOST_DEVICE
  explicit operator uint128_t() const {
    return hilo_.lo;
  }
};

/////////////////////////////////////////////////////////////////////////////////////////////////

} // namespace cutlass

/////////////////////////////////////////////////////////////////////////////////////////////////