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113 lines
3.0 KiB
113 lines
3.0 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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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 internal |
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{ |
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template <typename IndexType> |
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class index_range |
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{ |
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public: |
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typedef IndexType index_type; |
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__host__ __device__ |
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index_range(index_type begin, index_type end) : m_begin(begin), m_end(end) {} |
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__host__ __device__ |
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index_type begin(void) const { return m_begin; } |
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__host__ __device__ |
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index_type end(void) const { return m_end; } |
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__host__ __device__ |
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index_type size(void) const { return m_end - m_begin; } |
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private: |
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index_type m_begin; |
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index_type m_end; |
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}; |
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template <typename IndexType> |
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class uniform_decomposition |
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{ |
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public: |
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typedef IndexType index_type; |
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typedef index_range<index_type> range_type; |
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uniform_decomposition(index_type N, index_type granularity, index_type max_intervals) |
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: m_N(N), |
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m_intervals((N + granularity - 1) / granularity), |
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m_threshold(0), |
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m_small_interval(granularity), |
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m_large_interval(0) |
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{ |
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if(m_intervals > max_intervals) |
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{ |
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m_small_interval = granularity * (m_intervals / max_intervals); |
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m_large_interval = m_small_interval + granularity; |
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m_threshold = m_intervals % max_intervals; |
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m_intervals = max_intervals; |
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} |
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} |
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__host__ __device__ |
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index_range<index_type> operator[](const index_type& i) const |
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{ |
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if (i < m_threshold) |
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{ |
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index_type begin = m_large_interval * i; |
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index_type end = begin + m_large_interval; |
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return range_type(begin, end); |
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} |
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else |
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{ |
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index_type begin = m_large_interval * m_threshold + m_small_interval * (i - m_threshold); |
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index_type end = (begin + m_small_interval < m_N) ? begin + m_small_interval : m_N; |
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return range_type(begin, end); |
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} |
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} |
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__host__ __device__ |
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index_type size(void) const |
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{ |
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return m_intervals; |
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} |
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private: |
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index_type m_N; |
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index_type m_intervals; |
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index_type m_threshold; |
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index_type m_small_interval; |
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index_type m_large_interval; |
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}; |
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} // end namespace internal |
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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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