63e88f80
 Hu Chunming
提交三方库
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//---------------------------------------------------------------------------//
// Copyright (c) 2013-2014 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_FUNCTIONAL_POPCOUNT_HPP
#define BOOST_COMPUTE_FUNCTIONAL_POPCOUNT_HPP
#include <boost/compute/function.hpp>
#include <boost/compute/type_traits/type_name.hpp>
namespace boost {
namespace compute {
/// Returns the number of non-zero bits in \p x.
///
/// \see_opencl_ref{popcount}
template<class T>
class popcount : public function<T(T)>
{
public:
popcount()
: function<T(T)>("boost_popcount")
{
std::stringstream s;
s << "inline " << type_name<T>() << " boost_popcount"
<< "(const " << type_name<T>() << " x)\n"
<< "{\n"
// use built-in popcount if opencl 1.2 is supported
<< "#if __OPENCL_VERSION__ >= 120\n"
<< " return popcount(x);\n"
// fallback to generic popcount() implementation
<< "#else\n"
<< " " << type_name<T>() << " count = 0;\n"
<< " for(" << type_name<T>() << " i = 0; i < sizeof(i) * CHAR_BIT; i++){\n"
<< " if(x & (" << type_name<T>() << ") 1 << i){\n"
<< " count++;\n"
<< " }\n"
<< " }\n"
<< " return count;\n"
<< "#endif\n"
<< "}\n";
this->set_source(s.str());
}
};
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_FUNCTIONAL_POPCOUNT_HPP
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