56 lines
1.8 KiB
C++
56 lines
1.8 KiB
C++
//---------------------------------------------------------------------------//
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// Copyright (c) 2013-2014 Kyle Lutz <kyle.r.lutz@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_FUNCTIONAL_POPCOUNT_HPP
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#define BOOST_COMPUTE_FUNCTIONAL_POPCOUNT_HPP
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#include <boost/compute/function.hpp>
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#include <boost/compute/type_traits/type_name.hpp>
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namespace boost {
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namespace compute {
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/// Returns the number of non-zero bits in \p x.
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///
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/// \see_opencl_ref{popcount}
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template<class T>
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class popcount : public function<T(T)>
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{
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public:
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popcount()
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: function<T(T)>("boost_popcount")
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{
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std::stringstream s;
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s << "inline " << type_name<T>() << " boost_popcount"
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<< "(const " << type_name<T>() << " x)\n"
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<< "{\n"
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// use built-in popcount if opencl 1.2 is supported
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<< "#if __OPENCL_VERSION__ >= 120\n"
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<< " return popcount(x);\n"
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// fallback to generic popcount() implementation
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<< "#else\n"
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<< " " << type_name<T>() << " count = 0;\n"
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<< " for(" << type_name<T>() << " i = 0; i < sizeof(i) * CHAR_BIT; i++){\n"
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<< " if(x & (" << type_name<T>() << ") 1 << i){\n"
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<< " count++;\n"
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<< " }\n"
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<< " }\n"
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<< " return count;\n"
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<< "#endif\n"
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<< "}\n";
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this->set_source(s.str());
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}
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};
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_FUNCTIONAL_POPCOUNT_HPP
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