mirror of
https://github.com/boostorg/safe_numerics.git
synced 2026-02-09 11:22:23 +00:00
65 lines
1.5 KiB
C++
65 lines
1.5 KiB
C++
#ifndef BOOST_NUMERIC_UTILITY_HPP
|
|
#define BOOST_NUMERIC_UTILITY_HPP
|
|
|
|
// MS compatible compilers support #pragma once
|
|
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
|
|
# pragma once
|
|
#endif
|
|
|
|
// Copyright (c) 2015 Robert Ramey
|
|
//
|
|
// 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)
|
|
|
|
#include <cstdint> // intmax_t, uintmax_t
|
|
#include <algorithm>
|
|
#include <boost/integer.hpp> // (u)int_t<>::least, exact
|
|
|
|
namespace boost {
|
|
namespace numeric {
|
|
template<typename T>
|
|
typename std::enable_if<
|
|
! std::is_signed<T>::value,
|
|
unsigned int
|
|
>::type
|
|
constexpr log(T x){
|
|
unsigned i = 0;
|
|
for(; x > 0; ++i)
|
|
x >>= 1;
|
|
return i;
|
|
}
|
|
template<typename T>
|
|
typename std::enable_if<
|
|
std::is_signed<T>::value,
|
|
unsigned int
|
|
>::type
|
|
constexpr log(T x){
|
|
if(x < 0)
|
|
x = ~x;
|
|
return log(
|
|
static_cast<typename std::make_unsigned<T>::type>(x)
|
|
) + 1;
|
|
}
|
|
template<
|
|
std::intmax_t Min,
|
|
std::intmax_t Max
|
|
>
|
|
using signed_stored_type = typename boost::int_t<
|
|
std::max(log(Min), log(Max))
|
|
>::least ;
|
|
|
|
template<
|
|
std::uintmax_t Min,
|
|
std::uintmax_t Max
|
|
>
|
|
using unsigned_stored_type = typename boost::uint_t<
|
|
std::max(log(Min), log(Max))
|
|
>::least ;
|
|
|
|
|
|
} // numeric
|
|
} // boost
|
|
|
|
#endif // BOOST_NUMERIC_UTILITY_HPP
|