63e88f80
 Hu Chunming
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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_HASH_HPP
#define BOOST_COMPUTE_FUNCTIONAL_HASH_HPP
#include <boost/compute/function.hpp>
#include <boost/compute/types/fundamental.hpp>
namespace boost {
namespace compute {
namespace detail {
template<class Key>
std::string make_hash_function_name()
{
return std::string("boost_hash_") + type_name<Key>();
}
template<class Key>
inline std::string make_hash_function_source()
{
std::stringstream source;
source << "inline ulong " << make_hash_function_name<Key>()
<< "(const " << type_name<Key>() << " x)\n"
<< "{\n"
// note we reinterpret the argument as a 32-bit uint and
// then promote it to a 64-bit ulong for the result type
<< " ulong a = as_uint(x);\n"
<< " a = (a ^ 61) ^ (a >> 16);\n"
<< " a = a + (a << 3);\n"
<< " a = a ^ (a >> 4);\n"
<< " a = a * 0x27d4eb2d;\n"
<< " a = a ^ (a >> 15);\n"
<< " return a;\n"
<< "}\n";
return source.str();
}
template<class Key>
struct hash_impl
{
typedef Key argument_type;
typedef ulong_ result_type;
hash_impl()
: m_function("")
{
m_function = make_function_from_source<result_type(argument_type)>(
make_hash_function_name<argument_type>(),
make_hash_function_source<argument_type>()
);
}
template<class Arg>
invoked_function<result_type, boost::tuple<Arg> >
operator()(const Arg &arg) const
{
return m_function(arg);
}
function<result_type(argument_type)> m_function;
};
} // end detail namespace
/// The hash function returns a hash value for the input value.
///
/// The return type is \c ulong_ (the OpenCL unsigned long type).
template<class Key> struct hash;
/// \internal_
template<> struct hash<int_> : detail::hash_impl<int_> { };
/// \internal_
template<> struct hash<uint_> : detail::hash_impl<uint_> { };
/// \internal_
template<> struct hash<float_> : detail::hash_impl<float_> { };
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_FUNCTIONAL_HASH_HPP
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