//---------------------------------------------------------------------------//
|
// 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
|
