diff options
Diffstat (limited to '3rdParty/Boost/src/boost/random/detail/integer_log2.hpp')
-rw-r--r-- | 3rdParty/Boost/src/boost/random/detail/integer_log2.hpp | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/3rdParty/Boost/src/boost/random/detail/integer_log2.hpp b/3rdParty/Boost/src/boost/random/detail/integer_log2.hpp new file mode 100644 index 0000000..3770fc0 --- /dev/null +++ b/3rdParty/Boost/src/boost/random/detail/integer_log2.hpp @@ -0,0 +1,72 @@ +/* boost random/detail/integer_log2.hpp header file + * + * Copyright Steven Watanabe 2011 + * 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://www.boost.org for most recent version including documentation. + * + * $Id: integer_log2.hpp 72861 2011-07-02 20:26:19Z danieljames $ + * + */ + +#ifndef BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP +#define BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP + +#include <boost/config.hpp> +#include <boost/limits.hpp> +#include <boost/pending/integer_log2.hpp> + +namespace boost { +namespace random { +namespace detail { + +// Daniel James: Disabled use of constexpr because integer_log2_impl is not a +// valid constexpr. +#if 0 && !defined(BOOST_NO_CONSTEXPR) +#define BOOST_RANDOM_DETAIL_CONSTEXPR constexpr +#elif defined(BOOST_MSVC) +#define BOOST_RANDOM_DETAIL_CONSTEXPR __forceinline +#elif defined(__GNUC__) && __GNUC__ >= 4 +#define BOOST_RANDOM_DETAIL_CONSTEXPR __attribute__((const)) __attribute__((always_inline)) +#else +#define BOOST_RANDOM_DETAIL_CONSTEXPR inline +#endif + +template<int Shift> +struct integer_log2_impl +{ + template<class T> + BOOST_RANDOM_DETAIL_CONSTEXPR static int apply(T t, int accum) + { + int update = ((t >> Shift) != 0) * Shift; + return integer_log2_impl<Shift / 2>::apply(t >> update, accum + update); + } +}; + +template<> +struct integer_log2_impl<1> +{ + template<class T> + BOOST_RANDOM_DETAIL_CONSTEXPR static int apply(T t, int accum) + { + return int(t >> 1) + accum; + } +}; + +template<class T> +BOOST_RANDOM_DETAIL_CONSTEXPR int integer_log2(T t) +{ + return integer_log2_impl< + ::boost::detail::max_pow2_less< + ::std::numeric_limits<T>::digits, 4 + >::value + >::apply(t, 0); +} + +} // namespace detail +} // namespace random +} // namespace boost + +#endif // BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP |