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/**
 * @file
 * The cub::BlockHistogramAtomic class provides atomic-based methods for constructing block-wide
 * histograms from data samples partitioned across a CUDA thread block.
 */

#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

CUB_NAMESPACE_BEGIN

/**
 * @brief The BlockHistogramAtomic class provides atomic-based methods for constructing block-wide
 *        histograms from data samples partitioned across a CUDA thread block.
 */
template <int BINS>
struct BlockHistogramAtomic
{
    /// Shared memory storage layout type
    struct TempStorage {};


    /// Constructor
    __device__ __forceinline__ BlockHistogramAtomic(
        TempStorage &temp_storage)
    {}

    /**
     * @brief Composite data onto an existing histogram
     *
     * @param[in] items
     *   Calling thread's input values to histogram
     *
     * @param[out] histogram
     *   Reference to shared/device-accessible memory histogram
     */
    template <typename T, typename CounterT, int ITEMS_PER_THREAD>
    __device__ __forceinline__ void Composite(T (&items)[ITEMS_PER_THREAD],
                                              CounterT histogram[BINS])
    {
      // Update histogram
      #pragma unroll
      for (int i = 0; i < ITEMS_PER_THREAD; ++i)
      {
        atomicAdd(histogram + items[i], 1);
      }
    }
};

CUB_NAMESPACE_END

