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126 lines
4.2 KiB
126 lines
4.2 KiB
/* |
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* Copyright 2008-2012 NVIDIA Corporation |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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#pragma once |
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#include <thrust/detail/config.h> |
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#include <thrust/system/tbb/detail/execution_policy.h> |
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#include <tbb/parallel_for.h> |
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#include <thrust/iterator/iterator_traits.h> |
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#include <thrust/detail/minmax.h> |
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#include <thrust/system/cpp/memory.h> |
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#include <thrust/reduce.h> |
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#include <cassert> |
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namespace thrust |
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{ |
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namespace system |
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{ |
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namespace tbb |
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{ |
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namespace detail |
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{ |
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namespace reduce_intervals_detail |
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{ |
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template<typename L, typename R> |
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inline L divide_ri(const L x, const R y) |
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{ |
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return (x + (y - 1)) / y; |
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} |
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template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Size, typename BinaryFunction> |
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struct body |
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{ |
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RandomAccessIterator1 first; |
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RandomAccessIterator2 result; |
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Size n, interval_size; |
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BinaryFunction binary_op; |
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body(RandomAccessIterator1 first, RandomAccessIterator2 result, Size n, Size interval_size, BinaryFunction binary_op) |
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: first(first), result(result), n(n), interval_size(interval_size), binary_op(binary_op) |
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{} |
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void operator()(const ::tbb::blocked_range<Size> &r) const |
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{ |
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assert(r.size() == 1); |
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Size interval_idx = r.begin(); |
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Size offset_to_first = interval_size * interval_idx; |
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Size offset_to_last = thrust::min(n, offset_to_first + interval_size); |
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RandomAccessIterator1 my_first = first + offset_to_first; |
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RandomAccessIterator1 my_last = first + offset_to_last; |
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thrust::cpp::tag seq; |
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// carefully pass the init value for the interval with raw_reference_cast |
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typedef typename BinaryFunction::result_type sum_type; |
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result[interval_idx] = |
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thrust::reduce(seq, my_first + 1, my_last, sum_type(thrust::raw_reference_cast(*my_first)), binary_op); |
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} |
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}; |
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template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename Size, typename BinaryFunction> |
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body<RandomAccessIterator1,RandomAccessIterator2,Size,BinaryFunction> |
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make_body(RandomAccessIterator1 first, RandomAccessIterator2 result, Size n, Size interval_size, BinaryFunction binary_op) |
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{ |
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return body<RandomAccessIterator1,RandomAccessIterator2,Size,BinaryFunction>(first, result, n, interval_size, binary_op); |
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} |
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} // end reduce_intervals_detail |
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template<typename DerivedPolicy, typename RandomAccessIterator1, typename Size, typename RandomAccessIterator2, typename BinaryFunction> |
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void reduce_intervals(thrust::tbb::execution_policy<DerivedPolicy> &, |
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RandomAccessIterator1 first, |
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RandomAccessIterator1 last, |
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Size interval_size, |
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RandomAccessIterator2 result, |
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BinaryFunction binary_op) |
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{ |
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typename thrust::iterator_difference<RandomAccessIterator1>::type n = last - first; |
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Size num_intervals = reduce_intervals_detail::divide_ri(n, interval_size); |
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::tbb::parallel_for(::tbb::blocked_range<Size>(0, num_intervals, 1), reduce_intervals_detail::make_body(first, result, Size(n), interval_size, binary_op), ::tbb::simple_partitioner()); |
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} |
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template<typename DerivedPolicy, typename RandomAccessIterator1, typename Size, typename RandomAccessIterator2> |
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void reduce_intervals(thrust::tbb::execution_policy<DerivedPolicy> &exec, |
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RandomAccessIterator1 first, |
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RandomAccessIterator1 last, |
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Size interval_size, |
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RandomAccessIterator2 result) |
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{ |
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typedef typename thrust::iterator_value<RandomAccessIterator1>::type value_type; |
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return thrust::system::tbb::detail::reduce_intervals(exec, first, last, interval_size, result, thrust::plus<value_type>()); |
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} |
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} // end detail |
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} // end tbb |
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} // end system |
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} // end thrust |
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