root/modules/cudev/include/opencv2/cudev/block/scan.hpp

INCLUDED FROM

DEFINITIONS

1. blockScanInclusive
2. blockScanExclusive

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#pragma once

#ifndef __OPENCV_CUDEV_BLOCK_SCAN_HPP__
#define __OPENCV_CUDEV_BLOCK_SCAN_HPP__

#include "../common.hpp"
#include "../warp/scan.hpp"

namespace cv { namespace cudev {

//! @addtogroup cudev
//! @{

template <int THREADS_NUM, typename T>
__device__ T blockScanInclusive(T data, volatile T* smem, uint tid)
{
    if (THREADS_NUM > WARP_SIZE)
    {
        // bottom-level inclusive warp scan
        T warpResult = warpScanInclusive(data, smem, tid);

        __syncthreads();

        // save top elements of each warp for exclusive warp scan
        // sync to wait for warp scans to complete (because s_Data is being overwritten)
        if ((tid & (WARP_SIZE - 1)) == (WARP_SIZE - 1))
        {
            smem[tid >> LOG_WARP_SIZE] = warpResult;
        }

        __syncthreads();

        if (tid < (THREADS_NUM / WARP_SIZE))
        {
            // grab top warp elements
            T val = smem[tid];

            // calculate exclusive scan and write back to shared memory
            smem[tid] = warpScanExclusive(val, smem, tid);
        }

        __syncthreads();

        // return updated warp scans with exclusive scan results
        return warpResult + smem[tid >> LOG_WARP_SIZE];
    }
    else
    {
        return warpScanInclusive(data, smem, tid);
    }
}

template <int THREADS_NUM, typename T>
__device__ __forceinline__ T blockScanExclusive(T data, volatile T* smem, uint tid)
{
    return blockScanInclusive<THREADS_NUM>(data, smem, tid) - data;
}

//! @}

}}

#endif