thread_reduce.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.
*
******************************************************************************/
/**
* \file
* Thread utilities for sequential reduction over statically-sized array types
*/
#pragma once
#include "../thread/thread_operators.cuh"
#include "../util_namespace.cuh"
/// Optional outer namespace(s)
CUB_NS_PREFIX
/// CUB namespace
namespace cub {
/// Internal namespace (to prevent ADL mishaps between static functions when mixing different CUB installations)
namespace internal {
/**
* Sequential reduction over statically-sized array types
*/
template <
int LENGTH,
typename T,
typename ReductionOp>
__device__ __forceinline__ T ThreadReduce(
T* input, ///< [in] Input array
ReductionOp reduction_op, ///< [in] Binary reduction operator
T prefix, ///< [in] Prefix to seed reduction with
Int2Type<LENGTH> /*length*/)
{
T retval = prefix;
#pragma unroll
for (int i = 0; i < LENGTH; ++i)
retval = reduction_op(retval, input[i]);
return retval;
}
/**
* \brief Perform a sequential reduction over \p LENGTH elements of the \p input array, seeded with the specified \p prefix. The aggregate is returned.
*
* \tparam LENGTH LengthT of input array
* \tparam T <b>[inferred]</b> The data type to be reduced.
* \tparam ScanOp <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
*/
template <
int LENGTH,
typename T,
typename ReductionOp>
__device__ __forceinline__ T ThreadReduce(
T* input, ///< [in] Input array
ReductionOp reduction_op, ///< [in] Binary reduction operator
T prefix) ///< [in] Prefix to seed reduction with
{
return ThreadReduce(input, reduction_op, prefix, Int2Type<LENGTH>());
}
/**
* \brief Perform a sequential reduction over \p LENGTH elements of the \p input array. The aggregate is returned.
*
* \tparam LENGTH LengthT of input array
* \tparam T <b>[inferred]</b> The data type to be reduced.
* \tparam ScanOp <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
*/
template <
int LENGTH,
typename T,
typename ReductionOp>
__device__ __forceinline__ T ThreadReduce(
T* input, ///< [in] Input array
ReductionOp reduction_op) ///< [in] Binary reduction operator
{
T prefix = input[0];
return ThreadReduce<LENGTH - 1>(input + 1, reduction_op, prefix);
}
/**
* \brief Perform a sequential reduction over the statically-sized \p input array, seeded with the specified \p prefix. The aggregate is returned.
*
* \tparam LENGTH <b>[inferred]</b> LengthT of \p input array
* \tparam T <b>[inferred]</b> The data type to be reduced.
* \tparam ScanOp <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
*/
template <
int LENGTH,
typename T,
typename ReductionOp>
__device__ __forceinline__ T ThreadReduce(
T (&input)[LENGTH], ///< [in] Input array
ReductionOp reduction_op, ///< [in] Binary reduction operator
T prefix) ///< [in] Prefix to seed reduction with
{
return ThreadReduce(input, reduction_op, prefix, Int2Type<LENGTH>());
}
/**
* \brief Serial reduction with the specified operator
*
* \tparam LENGTH <b>[inferred]</b> LengthT of \p input array
* \tparam T <b>[inferred]</b> The data type to be reduced.
* \tparam ScanOp <b>[inferred]</b> Binary reduction operator type having member <tt>T operator()(const T &a, const T &b)</tt>
*/
template <
int LENGTH,
typename T,
typename ReductionOp>
__device__ __forceinline__ T ThreadReduce(
T (&input)[LENGTH], ///< [in] Input array
ReductionOp reduction_op) ///< [in] Binary reduction operator
{
return ThreadReduce<LENGTH>((T*) input, reduction_op);
}
} // internal namespace
} // CUB namespace
CUB_NS_POSTFIX // Optional outer namespace(s)