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244 lines
8.9 KiB
244 lines
8.9 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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/*! \file distance.h |
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* \brief Device implementations for distance. |
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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/extrema.h> |
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#include <thrust/functional.h> |
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#include <thrust/pair.h> |
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#include <thrust/reduce.h> |
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#include <thrust/transform_reduce.h> |
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#include <thrust/iterator/iterator_traits.h> |
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#include <thrust/iterator/counting_iterator.h> |
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#include <thrust/iterator/zip_iterator.h> |
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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 detail |
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{ |
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namespace generic |
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{ |
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namespace detail |
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{ |
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////////////// |
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// Functors // |
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////////////// |
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// return the smaller/larger element making sure to prefer the |
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// first occurance of the minimum/maximum element |
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template <typename InputType, typename IndexType, typename BinaryPredicate> |
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struct min_element_reduction |
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{ |
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BinaryPredicate comp; |
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__host__ __device__ |
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min_element_reduction(BinaryPredicate comp) : comp(comp){} |
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__host__ __device__ |
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thrust::tuple<InputType, IndexType> |
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operator()(const thrust::tuple<InputType, IndexType>& lhs, |
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const thrust::tuple<InputType, IndexType>& rhs ) |
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{ |
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if(comp(thrust::get<0>(lhs), thrust::get<0>(rhs))) |
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return lhs; |
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if(comp(thrust::get<0>(rhs), thrust::get<0>(lhs))) |
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return rhs; |
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// values are equivalent, prefer value with smaller index |
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if(thrust::get<1>(lhs) < thrust::get<1>(rhs)) |
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return lhs; |
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else |
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return rhs; |
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} // end operator()() |
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}; // end min_element_reduction |
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template <typename InputType, typename IndexType, typename BinaryPredicate> |
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struct max_element_reduction |
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{ |
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BinaryPredicate comp; |
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__host__ __device__ |
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max_element_reduction(BinaryPredicate comp) : comp(comp){} |
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__host__ __device__ |
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thrust::tuple<InputType, IndexType> |
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operator()(const thrust::tuple<InputType, IndexType>& lhs, |
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const thrust::tuple<InputType, IndexType>& rhs ) |
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{ |
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if(comp(thrust::get<0>(lhs), thrust::get<0>(rhs))) |
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return rhs; |
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if(comp(thrust::get<0>(rhs), thrust::get<0>(lhs))) |
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return lhs; |
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// values are equivalent, prefer value with smaller index |
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if(thrust::get<1>(lhs) < thrust::get<1>(rhs)) |
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return lhs; |
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else |
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return rhs; |
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} // end operator()() |
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}; // end max_element_reduction |
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// return the smaller & larger element making sure to prefer the |
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// first occurance of the minimum/maximum element |
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template <typename InputType, typename IndexType, typename BinaryPredicate> |
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struct minmax_element_reduction |
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{ |
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BinaryPredicate comp; |
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minmax_element_reduction(BinaryPredicate comp) : comp(comp){} |
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__host__ __device__ |
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thrust::tuple< thrust::tuple<InputType,IndexType>, thrust::tuple<InputType,IndexType> > |
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operator()(const thrust::tuple< thrust::tuple<InputType,IndexType>, thrust::tuple<InputType,IndexType> >& lhs, |
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const thrust::tuple< thrust::tuple<InputType,IndexType>, thrust::tuple<InputType,IndexType> >& rhs ) |
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{ |
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return thrust::make_tuple(min_element_reduction<InputType, IndexType, BinaryPredicate>(comp)(thrust::get<0>(lhs), thrust::get<0>(rhs)), |
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max_element_reduction<InputType, IndexType, BinaryPredicate>(comp)(thrust::get<1>(lhs), thrust::get<1>(rhs))); |
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} // end operator()() |
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}; // end minmax_element_reduction |
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template <typename InputType, typename IndexType> |
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struct duplicate_tuple |
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{ |
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__host__ __device__ |
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thrust::tuple< thrust::tuple<InputType,IndexType>, thrust::tuple<InputType,IndexType> > |
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operator()(const thrust::tuple<InputType,IndexType>& t) |
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{ |
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return thrust::make_tuple(t, t); |
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} |
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}; // end duplicate_tuple |
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} // end namespace detail |
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template <typename DerivedPolicy, typename ForwardIterator> |
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ForwardIterator min_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last) |
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{ |
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typedef typename thrust::iterator_value<ForwardIterator>::type value_type; |
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return thrust::min_element(exec, first, last, thrust::less<value_type>()); |
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} // end min_element() |
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template <typename DerivedPolicy, typename ForwardIterator, typename BinaryPredicate> |
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ForwardIterator min_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last, |
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BinaryPredicate comp) |
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{ |
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if (first == last) |
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return last; |
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typedef typename thrust::iterator_traits<ForwardIterator>::value_type InputType; |
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typedef typename thrust::iterator_traits<ForwardIterator>::difference_type IndexType; |
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thrust::tuple<InputType, IndexType> result = |
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thrust::reduce |
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(exec, |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))), |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))) + (last - first), |
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thrust::tuple<InputType, IndexType>(*first, 0), |
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detail::min_element_reduction<InputType, IndexType, BinaryPredicate>(comp)); |
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return first + thrust::get<1>(result); |
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} // end min_element() |
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template <typename DerivedPolicy, typename ForwardIterator> |
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ForwardIterator max_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last) |
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{ |
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typedef typename thrust::iterator_value<ForwardIterator>::type value_type; |
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return thrust::max_element(exec, first, last, thrust::less<value_type>()); |
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} // end max_element() |
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template <typename DerivedPolicy, typename ForwardIterator, typename BinaryPredicate> |
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ForwardIterator max_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last, |
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BinaryPredicate comp) |
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{ |
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if (first == last) |
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return last; |
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typedef typename thrust::iterator_traits<ForwardIterator>::value_type InputType; |
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typedef typename thrust::iterator_traits<ForwardIterator>::difference_type IndexType; |
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thrust::tuple<InputType, IndexType> result = |
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thrust::reduce |
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(exec, |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))), |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))) + (last - first), |
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thrust::tuple<InputType, IndexType>(*first, 0), |
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detail::max_element_reduction<InputType, IndexType, BinaryPredicate>(comp)); |
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return first + thrust::get<1>(result); |
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} // end max_element() |
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template <typename DerivedPolicy, typename ForwardIterator> |
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thrust::pair<ForwardIterator,ForwardIterator> minmax_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last) |
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{ |
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typedef typename thrust::iterator_value<ForwardIterator>::type value_type; |
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return thrust::minmax_element(exec, first, last, thrust::less<value_type>()); |
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} // end minmax_element() |
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template <typename DerivedPolicy, typename ForwardIterator, typename BinaryPredicate> |
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thrust::pair<ForwardIterator,ForwardIterator> minmax_element(thrust::execution_policy<DerivedPolicy> &exec, |
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ForwardIterator first, |
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ForwardIterator last, |
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BinaryPredicate comp) |
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{ |
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if (first == last) |
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return thrust::make_pair(last, last); |
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typedef typename thrust::iterator_traits<ForwardIterator>::value_type InputType; |
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typedef typename thrust::iterator_traits<ForwardIterator>::difference_type IndexType; |
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thrust::tuple< thrust::tuple<InputType,IndexType>, thrust::tuple<InputType,IndexType> > result = |
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thrust::transform_reduce |
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(exec, |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))), |
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thrust::make_zip_iterator(thrust::make_tuple(first, thrust::counting_iterator<IndexType>(0))) + (last - first), |
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detail::duplicate_tuple<InputType, IndexType>(), |
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detail::duplicate_tuple<InputType, IndexType>()(thrust::tuple<InputType, IndexType>(*first, 0)), |
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detail::minmax_element_reduction<InputType, IndexType, BinaryPredicate>(comp)); |
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return thrust::make_pair(first + thrust::get<1>(thrust::get<0>(result)), first + thrust::get<1>(thrust::get<1>(result))); |
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} // end minmax_element() |
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} // end namespace generic |
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} // end namespace detail |
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} // end namespace system |
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} // end namespace thrust |
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