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Sprout/sprout/integer/static_pow.hpp

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2013-10-09 07:14:41 +00:00
/*=============================================================================
Copyright (c) 2011-2013 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
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)
=============================================================================*/
#ifndef SPROUT_INTEGER_STATIC_POW_HPP
#define SPROUT_INTEGER_STATIC_POW_HPP
#include <type_traits>
#include <sprout/config.hpp>
namespace sprout {
//
// static_pow2
//
template<typename T, T X>
struct static_pow2
: public std::integral_constant<T, (1 << X)>
{};
namespace detail {
template<typename T, T X, bool IsZero = (X == 0)>
struct static_pow2m1;
template<typename T, T X>
struct static_pow2m1<T, X, true>
: public std::integral_constant<T, 1>
{};
template<typename T, T X>
struct static_pow2m1<T, X, false>
: public std::integral_constant<T, ((((T(1) << (X - 1)) - 1) << 1) + 1)>
{};
} // namespace detail
//
// static_pow2m1
//
template<typename T, T X>
struct static_pow2m1
: public sprout::detail::static_pow2m1<T, X>
{};
namespace detail {
template<typename T, T X, T Y, int K = (Y < 3 ? int(Y) : 3), bool IsOdd = (Y % 2 != 0)>
struct static_pow;
template<typename T, T X, T Y>
struct static_pow<T, X, Y, 0, false>
: public std::integral_constant<T, 1>
{};
template<typename T, T X, T Y>
struct static_pow<T, X, Y, 1, true>
: public std::integral_constant<T, X>
{};
template<typename T, T X, T Y>
struct static_pow<T, X, Y, 2, false>
: public std::integral_constant<T, X * X>
{};
template<typename T, T X, T Y, int K>
struct static_pow<T, X, Y, K, false>
: public sprout::detail::static_pow<T, sprout::detail::static_pow<T, X, Y / 2>::value, 2>
{};
template<typename T, T X, T Y, int K>
struct static_pow<T, X, Y, K, true>
: public std::integral_constant<T, X * sprout::detail::static_pow<T, X, Y - 1>::value>
{};
} // namespace detail
//
// static_pow
//
template<typename T, T X, T Y>
struct static_pow
: public sprout::detail::static_pow<T, X, Y>
{};
} // namespace sprout
#endif // #ifndef SPROUT_INTEGER_STATIC_POW_HPP