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