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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/system/tbb/detail/scan.h>
#include <thrust/distance.h>
#include <thrust/advance.h>
#include <thrust/iterator/iterator_traits.h>
#include <thrust/detail/function.h>
#include <thrust/detail/type_traits.h>
#include <thrust/detail/type_traits/function_traits.h>
#include <thrust/detail/type_traits/iterator/is_output_iterator.h>
#include <tbb/blocked_range.h>
#include <tbb/parallel_scan.h>
THRUST_NAMESPACE_BEGIN
namespace system
{
namespace tbb
{
namespace detail
{
namespace scan_detail
{
template<typename InputIterator,
typename OutputIterator,
typename BinaryFunction,
typename ValueType>
struct inclusive_body
{
InputIterator input;
OutputIterator output;
thrust::detail::wrapped_function<BinaryFunction,ValueType> binary_op;
ValueType sum;
bool first_call;
inclusive_body(InputIterator input, OutputIterator output, BinaryFunction binary_op, ValueType dummy)
: input(input), output(output), binary_op(binary_op), sum(dummy), first_call(true)
{}
inclusive_body(inclusive_body& b, ::tbb::split)
: input(b.input), output(b.output), binary_op(b.binary_op), sum(b.sum), first_call(true)
{}
template<typename Size>
void operator()(const ::tbb::blocked_range<Size>& r, ::tbb::pre_scan_tag)
{
InputIterator iter = input + r.begin();
ValueType temp = *iter;
++iter;
for (Size i = r.begin() + 1; i != r.end(); ++i, ++iter)
temp = binary_op(temp, *iter);
if (first_call)
sum = temp;
else
sum = binary_op(sum, temp);
first_call = false;
}
template<typename Size>
void operator()(const ::tbb::blocked_range<Size>& r, ::tbb::final_scan_tag)
{
InputIterator iter1 = input + r.begin();
OutputIterator iter2 = output + r.begin();
if (first_call)
{
*iter2 = sum = *iter1;
++iter1;
++iter2;
for (Size i = r.begin() + 1; i != r.end(); ++i, ++iter1, ++iter2)
*iter2 = sum = binary_op(sum, *iter1);
}
else
{
for (Size i = r.begin(); i != r.end(); ++i, ++iter1, ++iter2)
*iter2 = sum = binary_op(sum, *iter1);
}
first_call = false;
}
void reverse_join(inclusive_body& b)
{
// Only accumulate this functor's partial sum if this functor has been
// called at least once -- otherwise we'll over-count the initial value.
if (!first_call)
{
sum = binary_op(b.sum, sum);
}
}
void assign(inclusive_body& b)
{
sum = b.sum;
}
};
template<typename InputIterator,
typename OutputIterator,
typename BinaryFunction,
typename ValueType>
struct exclusive_body
{
InputIterator input;
OutputIterator output;
thrust::detail::wrapped_function<BinaryFunction,ValueType> binary_op;
ValueType sum;
bool first_call;
exclusive_body(InputIterator input, OutputIterator output, BinaryFunction binary_op, ValueType init)
: input(input), output(output), binary_op(binary_op), sum(init), first_call(true)
{}
exclusive_body(exclusive_body& b, ::tbb::split)
: input(b.input), output(b.output), binary_op(b.binary_op), sum(b.sum), first_call(true)
{}
template<typename Size>
void operator()(const ::tbb::blocked_range<Size>& r, ::tbb::pre_scan_tag)
{
InputIterator iter = input + r.begin();
ValueType temp = *iter;
++iter;
for (Size i = r.begin() + 1; i != r.end(); ++i, ++iter)
temp = binary_op(temp, *iter);
if (first_call && r.begin() > 0)
sum = temp;
else
sum = binary_op(sum, temp);
first_call = false;
}
template<typename Size>
void operator()(const ::tbb::blocked_range<Size>& r, ::tbb::final_scan_tag)
{
InputIterator iter1 = input + r.begin();
OutputIterator iter2 = output + r.begin();
for (Size i = r.begin(); i != r.end(); ++i, ++iter1, ++iter2)
{
ValueType temp = binary_op(sum, *iter1);
*iter2 = sum;
sum = temp;
}
first_call = false;
}
void reverse_join(exclusive_body& b)
{
// Only accumulate this functor's partial sum if this functor has been
// called at least once -- otherwise we'll over-count the initial value.
if (!first_call)
{
sum = binary_op(b.sum, sum);
}
}
void assign(exclusive_body& b)
{
sum = b.sum;
}
};
} // end scan_detail
template<typename InputIterator,
typename OutputIterator,
typename BinaryFunction>
OutputIterator inclusive_scan(tag,
InputIterator first,
InputIterator last,
OutputIterator result,
BinaryFunction binary_op)
{
using namespace thrust::detail;
// Use the input iterator's value type per https://wg21.link/P0571
using ValueType = typename thrust::iterator_value<InputIterator>::type;
using Size = typename thrust::iterator_difference<InputIterator>::type;
Size n = thrust::distance(first, last);
if (n != 0)
{
typedef typename scan_detail::inclusive_body<InputIterator,OutputIterator,BinaryFunction,ValueType> Body;
Body scan_body(first, result, binary_op, *first);
::tbb::parallel_scan(::tbb::blocked_range<Size>(0,n), scan_body);
}
thrust::advance(result, n);
return result;
}
template<typename InputIterator,
typename OutputIterator,
typename InitialValueType,
typename BinaryFunction>
OutputIterator exclusive_scan(tag,
InputIterator first,
InputIterator last,
OutputIterator result,
InitialValueType init,
BinaryFunction binary_op)
{
using namespace thrust::detail;
// Use the initial value type per https://wg21.link/P0571
using ValueType = InitialValueType;
using Size = typename thrust::iterator_difference<InputIterator>::type;
Size n = thrust::distance(first, last);
if (n != 0)
{
typedef typename scan_detail::exclusive_body<InputIterator,OutputIterator,BinaryFunction,ValueType> Body;
Body scan_body(first, result, binary_op, init);
::tbb::parallel_scan(::tbb::blocked_range<Size>(0,n), scan_body);
}
thrust::advance(result, n);
return result;
}
} // end namespace detail
} // end namespace tbb
} // end namespace system
THRUST_NAMESPACE_END
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