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//---------------------------------------------------------------------------//
// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// See http://boostorg.github.com/compute for more information.
//---------------------------------------------------------------------------//
#ifndef BOOST_COMPUTE_ALGORITHM_EXCLUSIVE_SCAN_HPP
#define BOOST_COMPUTE_ALGORITHM_EXCLUSIVE_SCAN_HPP
#include <boost/static_assert.hpp>
#include <boost/compute/functional.hpp>
#include <boost/compute/system.hpp>
#include <boost/compute/command_queue.hpp>
#include <boost/compute/algorithm/detail/scan.hpp>
#include <boost/compute/type_traits/is_device_iterator.hpp>
namespace boost {
namespace compute {
/// Performs an exclusive scan of the elements in the range [\p first, \p last)
/// and stores the results in the range beginning at \p result.
///
/// Each element in the output is assigned to the sum of all the previous
/// values in the input.
///
/// \param first first element in the range to scan
/// \param last last element in the range to scan
/// \param result first element in the result range
/// \param init value used to initialize the scan sequence
/// \param binary_op associative binary operator
/// \param queue command queue to perform the operation
///
/// \return \c OutputIterator to the end of the result range
///
/// The default operation is to add the elements up.
///
/// \snippet test/test_scan.cpp exclusive_scan_int
///
/// But different associative operation can be specified as \p binary_op
/// instead (e.g., multiplication, maximum, minimum). Also value used to
/// initialized the scan sequence can be specified.
///
/// \snippet test/test_scan.cpp exclusive_scan_int_multiplies
///
/// Space complexity on GPUs: \Omega(n)<br>
/// Space complexity on GPUs when \p first == \p result: \Omega(2n)<br>
/// Space complexity on CPUs: \Omega(1)
///
/// \see inclusive_scan()
template<class InputIterator, class OutputIterator, class T, class BinaryOperator>
inline OutputIterator
exclusive_scan(InputIterator first,
InputIterator last,
OutputIterator result,
T init,
BinaryOperator binary_op,
command_queue &queue = system::default_queue())
{
BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
return detail::scan(first, last, result, true, init, binary_op, queue);
}
/// \overload
template<class InputIterator, class OutputIterator, class T>
inline OutputIterator
exclusive_scan(InputIterator first,
InputIterator last,
OutputIterator result,
T init,
command_queue &queue = system::default_queue())
{
BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
typedef typename
std::iterator_traits<OutputIterator>::value_type output_type;
return detail::scan(first, last, result, true,
init, boost::compute::plus<output_type>(),
queue);
}
/// \overload
template<class InputIterator, class OutputIterator>
inline OutputIterator
exclusive_scan(InputIterator first,
InputIterator last,
OutputIterator result,
command_queue &queue = system::default_queue())
{
BOOST_STATIC_ASSERT(is_device_iterator<InputIterator>::value);
BOOST_STATIC_ASSERT(is_device_iterator<OutputIterator>::value);
typedef typename
std::iterator_traits<OutputIterator>::value_type output_type;
return detail::scan(first, last, result, true,
output_type(0), boost::compute::plus<output_type>(),
queue);
}
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ALGORITHM_EXCLUSIVE_SCAN_HPP
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