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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_DETAIL_SERIAL_SCAN_HPP
#define BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_SCAN_HPP
#include <iterator>
#include <boost/compute/device.hpp>
#include <boost/compute/kernel.hpp>
#include <boost/compute/command_queue.hpp>
#include <boost/compute/detail/meta_kernel.hpp>
#include <boost/compute/detail/iterator_range_size.hpp>
namespace boost {
namespace compute {
namespace detail {
template<class InputIterator, class OutputIterator, class T, class BinaryOperator>
inline OutputIterator serial_scan(InputIterator first,
InputIterator last,
OutputIterator result,
bool exclusive,
T init,
BinaryOperator op,
command_queue &queue)
{
if(first == last){
return result;
}
typedef typename
std::iterator_traits<InputIterator>::value_type input_type;
typedef typename
std::iterator_traits<OutputIterator>::value_type output_type;
const context &context = queue.get_context();
// create scan kernel
meta_kernel k("serial_scan");
// Arguments
size_t n_arg = k.add_arg<ulong_>("n");
size_t init_arg = k.add_arg<output_type>("initial_value");
if(!exclusive){
k <<
k.decl<const ulong_>("start_idx") << " = 1;\n" <<
k.decl<output_type>("sum") << " = " << first[0] << ";\n" <<
result[0] << " = sum;\n";
}
else {
k <<
k.decl<const ulong_>("start_idx") << " = 0;\n" <<
k.decl<output_type>("sum") << " = initial_value;\n";
}
k <<
"for(ulong i = start_idx; i < n; i++){\n" <<
k.decl<const input_type>("x") << " = "
<< first[k.var<ulong_>("i")] << ";\n";
if(exclusive){
k << result[k.var<ulong_>("i")] << " = sum;\n";
}
k << " sum = "
<< op(k.var<output_type>("sum"), k.var<output_type>("x"))
<< ";\n";
if(!exclusive){
k << result[k.var<ulong_>("i")] << " = sum;\n";
}
k << "}\n";
// compile scan kernel
kernel scan_kernel = k.compile(context);
// setup kernel arguments
size_t n = detail::iterator_range_size(first, last);
scan_kernel.set_arg<ulong_>(n_arg, n);
scan_kernel.set_arg<output_type>(init_arg, static_cast<output_type>(init));
// execute the kernel
queue.enqueue_1d_range_kernel(scan_kernel, 0, 1, 1);
// return iterator pointing to the end of the result range
return result + n;
}
} // end detail namespace
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SERIAL_SCAN_HPP
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