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93 lines
2.2 KiB
C++
93 lines
2.2 KiB
C++
#ifndef BOOST_NUMERIC_UTILITY_HPP
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#define BOOST_NUMERIC_UTILITY_HPP
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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// Copyright (c) 2015 Robert Ramey
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <cstdint> // intmax_t, uintmax_t
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#include <algorithm>
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#include <boost/integer.hpp> // (u)int_t<>::least, exact
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namespace boost {
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namespace numeric {
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// the number of bits required to render the value in x
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template<typename T>
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typename std::enable_if<
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// T being unsigned
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! std::is_signed<T>::value,
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std::uintmax_t
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>::type
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constexpr log(T x){
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std::uintmax_t i = 0;
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for(; x > 0; ++i)
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x >>= 1;
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return i;
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}
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template<typename T>
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typename std::enable_if<
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// T being signed
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std::is_signed<T>::value,
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std::uintmax_t
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>::type
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constexpr log(T x){
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if(x < 0)
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x = ~x;
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return log(
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static_cast<typename std::make_unsigned<T>::type>(x)
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) + 1;
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}
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// return type required to store a particular range
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template<
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std::intmax_t Min,
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std::intmax_t Max
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>
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// signed range
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using signed_stored_type = typename boost::int_t<
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std::max({log(Min), log(Max)})
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>::least ;
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template<
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std::uintmax_t Min,
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std::uintmax_t Max
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>
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// unsigned range
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using unsigned_stored_type = typename boost::uint_t<
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std::max({log(Min), log(Max)})
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>::least ;
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template<typename T>
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using bits = std::integral_constant<
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int,
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std::numeric_limits<T>::digits
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+ std::numeric_limits<T>::is_signed ? 1 : 0
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>;
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// used for debugging
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// usage - print_type<T>;
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// provokes error message with name of type T
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template<typename Tx>
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using print_type = typename Tx::error_message;
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template<int N>
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struct print_value
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{
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enum test : char {
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value = N < 0 ? N - 256 : N + 256
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};
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};
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} // numeric
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} // boost
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#endif // BOOST_NUMERIC_UTILITY_HPP
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