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/*
* Copyright 2008-2013 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <thrust/detail/config.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/system/omp/detail/reduce.h>
#include <thrust/system/omp/detail/default_decomposition.h>
#include <thrust/system/omp/detail/reduce_intervals.h>
THRUST_NAMESPACE_BEGIN
namespace system
{
namespace omp
{
namespace detail
{
template<typename DerivedPolicy,
typename InputIterator,
typename OutputType,
typename BinaryFunction>
OutputType reduce(execution_policy<DerivedPolicy> &exec,
InputIterator first,
InputIterator last,
OutputType init,
BinaryFunction binary_op)
{
typedef typename thrust::iterator_difference<InputIterator>::type difference_type;
const difference_type n = thrust::distance(first,last);
// determine first and second level decomposition
thrust::system::detail::internal::uniform_decomposition<difference_type> decomp1 = thrust::system::omp::detail::default_decomposition(n);
thrust::system::detail::internal::uniform_decomposition<difference_type> decomp2(decomp1.size() + 1, 1, 1);
// allocate storage for the initializer and partial sums
// XXX use select_system for Tag
thrust::detail::temporary_array<OutputType,DerivedPolicy> partial_sums(exec, decomp1.size() + 1);
// set first element of temp array to init
partial_sums[0] = init;
// accumulate partial sums (first level reduction)
thrust::system::omp::detail::reduce_intervals(exec, first, partial_sums.begin() + 1, binary_op, decomp1);
// reduce partial sums (second level reduction)
thrust::system::omp::detail::reduce_intervals(exec, partial_sums.begin(), partial_sums.begin(), binary_op, decomp2);
return partial_sums[0];
} // end reduce()
} // end detail
} // end omp
} // end system
THRUST_NAMESPACE_END
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