block_histogram.cuh

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/******************************************************************************
 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the NVIDIA CORPORATION nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 ******************************************************************************/

#pragma once

#include "specializations/block_histogram_sort.cuh"
#include "specializations/block_histogram_atomic.cuh"
#include "../util_ptx.cuh"
#include "../util_arch.cuh"
#include "../util_namespace.cuh"

CUB_NS_PREFIX

namespace cub {


/******************************************************************************
 * Algorithmic variants
 ******************************************************************************/

enum BlockHistogramAlgorithm
{

    BLOCK_HISTO_SORT,


    BLOCK_HISTO_ATOMIC,
};



/******************************************************************************
 * Block histogram
 ******************************************************************************/


template <
    typename                T,
    int                     BLOCK_DIM_X,
    int                     ITEMS_PER_THREAD,
    int                     BINS,
    BlockHistogramAlgorithm ALGORITHM           = BLOCK_HISTO_SORT,
    int                     BLOCK_DIM_Y         = 1,
    int                     BLOCK_DIM_Z         = 1,
    int                     PTX_ARCH            = CUB_PTX_ARCH>
class BlockHistogram
{
private:

    /******************************************************************************
     * Constants and type definitions
     ******************************************************************************/

    enum
    {
        BLOCK_THREADS = BLOCK_DIM_X * BLOCK_DIM_Y * BLOCK_DIM_Z,
    };

    static const BlockHistogramAlgorithm SAFE_ALGORITHM =
        ((ALGORITHM == BLOCK_HISTO_ATOMIC) && (PTX_ARCH < 120)) ?
            BLOCK_HISTO_SORT :
            ALGORITHM;

    typedef typename If<(SAFE_ALGORITHM == BLOCK_HISTO_SORT),
        BlockHistogramSort<T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH>,
        BlockHistogramAtomic<BINS> >::Type InternalBlockHistogram;

    typedef typename InternalBlockHistogram::TempStorage _TempStorage;


    /******************************************************************************
     * Thread fields
     ******************************************************************************/

    _TempStorage &temp_storage;

    unsigned int linear_tid;


    /******************************************************************************
     * Utility methods
     ******************************************************************************/

    __device__ __forceinline__ _TempStorage& PrivateStorage()
    {
        __shared__ _TempStorage private_storage;
        return private_storage;
    }


public:

    struct TempStorage : Uninitialized<_TempStorage> {};


    /******************************************************************/

    __device__ __forceinline__ BlockHistogram()
    :
        temp_storage(PrivateStorage()),
        linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z))
    {}


    __device__ __forceinline__ BlockHistogram(
        TempStorage &temp_storage)             
    :
        temp_storage(temp_storage.Alias()),
        linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z))
    {}


    /******************************************************************/


    template <typename CounterT     >
    __device__ __forceinline__ void InitHistogram(CounterT      histogram[BINS])
    {
        // Initialize histogram bin counts to zeros
        int histo_offset = 0;

        #pragma unroll
        for(; histo_offset + BLOCK_THREADS <= BINS; histo_offset += BLOCK_THREADS)
        {
            histogram[histo_offset + linear_tid] = 0;
        }
        // Finish up with guarded initialization if necessary
        if ((BINS % BLOCK_THREADS != 0) && (histo_offset + linear_tid < BINS))
        {
            histogram[histo_offset + linear_tid] = 0;
        }
    }


    template <
        typename            CounterT     >
    __device__ __forceinline__ void Histogram(
        T                   (&items)[ITEMS_PER_THREAD],     
        CounterT             histogram[BINS])                
    {
        // Initialize histogram bin counts to zeros
        InitHistogram(histogram);

        CTA_SYNC();

        // Composite the histogram
        InternalBlockHistogram(temp_storage).Composite(items, histogram);
    }



    template <
        typename            CounterT     >
    __device__ __forceinline__ void Composite(
        T                   (&items)[ITEMS_PER_THREAD],     
        CounterT             histogram[BINS])                 
    {
        InternalBlockHistogram(temp_storage).Composite(items, histogram);
    }

};

}               // CUB namespace
CUB_NS_POSTFIX  // Optional outer namespace(s)