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Diffstat (limited to 'boost/compute/functional/hash.hpp')
-rw-r--r-- | boost/compute/functional/hash.hpp | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/boost/compute/functional/hash.hpp b/boost/compute/functional/hash.hpp new file mode 100644 index 0000000000..830c422fdb --- /dev/null +++ b/boost/compute/functional/hash.hpp @@ -0,0 +1,91 @@ +//---------------------------------------------------------------------------// +// 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 |