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// <bit> -*- C++ -*-
// Copyright (C) 2018-2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/bit
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_BIT
#define _GLIBCXX_BIT 1
#pragma GCC system_header
#if __cplusplus >= 201402L
#include <type_traits>
#include <limits>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
constexpr _Tp
__rotl(_Tp __x, int __s) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
const int __r = __s % _Nd;
if (__r == 0)
return __x;
else if (__r > 0)
return (__x << __r) | (__x >> ((_Nd - __r) % _Nd));
else
return (__x >> -__r) | (__x << ((_Nd + __r) % _Nd)); // rotr(x, -r)
}
template<typename _Tp>
constexpr _Tp
__rotr(_Tp __x, int __s) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
const int __r = __s % _Nd;
if (__r == 0)
return __x;
else if (__r > 0)
return (__x >> __r) | (__x << ((_Nd - __r) % _Nd));
else
return (__x << -__r) | (__x >> ((_Nd + __r) % _Nd)); // rotl(x, -r)
}
template<typename _Tp>
constexpr int
__countl_zero(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
if (__x == 0)
return _Nd;
constexpr auto _Nd_ull = numeric_limits<unsigned long long>::digits;
constexpr auto _Nd_ul = numeric_limits<unsigned long>::digits;
constexpr auto _Nd_u = numeric_limits<unsigned>::digits;
if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
{
constexpr int __diff = _Nd_u - _Nd;
return __builtin_clz(__x) - __diff;
}
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
{
constexpr int __diff = _Nd_ul - _Nd;
return __builtin_clzl(__x) - __diff;
}
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
{
constexpr int __diff = _Nd_ull - _Nd;
return __builtin_clzll(__x) - __diff;
}
else // (_Nd > _Nd_ull)
{
static_assert(_Nd <= (2 * _Nd_ull),
"Maximum supported integer size is 128-bit");
unsigned long long __high = __x >> _Nd_ull;
if (__high != 0)
{
constexpr int __diff = (2 * _Nd_ull) - _Nd;
return __builtin_clzll(__high) - __diff;
}
constexpr auto __max_ull = numeric_limits<unsigned long long>::max();
unsigned long long __low = __x & __max_ull;
return (_Nd - _Nd_ull) + __builtin_clzll(__low);
}
}
template<typename _Tp>
constexpr int
__countl_one(_Tp __x) noexcept
{
if (__x == numeric_limits<_Tp>::max())
return numeric_limits<_Tp>::digits;
return std::__countl_zero<_Tp>((_Tp)~__x);
}
template<typename _Tp>
constexpr int
__countr_zero(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
if (__x == 0)
return _Nd;
constexpr auto _Nd_ull = numeric_limits<unsigned long long>::digits;
constexpr auto _Nd_ul = numeric_limits<unsigned long>::digits;
constexpr auto _Nd_u = numeric_limits<unsigned>::digits;
if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
return __builtin_ctz(__x);
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
return __builtin_ctzl(__x);
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
return __builtin_ctzll(__x);
else // (_Nd > _Nd_ull)
{
static_assert(_Nd <= (2 * _Nd_ull),
"Maximum supported integer size is 128-bit");
constexpr auto __max_ull = numeric_limits<unsigned long long>::max();
unsigned long long __low = __x & __max_ull;
if (__low != 0)
return __builtin_ctzll(__low);
unsigned long long __high = __x >> _Nd_ull;
return __builtin_ctzll(__high) + _Nd_ull;
}
}
template<typename _Tp>
constexpr int
__countr_one(_Tp __x) noexcept
{
if (__x == numeric_limits<_Tp>::max())
return numeric_limits<_Tp>::digits;
return std::__countr_zero((_Tp)~__x);
}
template<typename _Tp>
constexpr int
__popcount(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
if (__x == 0)
return 0;
constexpr auto _Nd_ull = numeric_limits<unsigned long long>::digits;
constexpr auto _Nd_ul = numeric_limits<unsigned long>::digits;
constexpr auto _Nd_u = numeric_limits<unsigned>::digits;
if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
return __builtin_popcount(__x);
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
return __builtin_popcountl(__x);
else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
return __builtin_popcountll(__x);
else // (_Nd > _Nd_ull)
{
static_assert(_Nd <= (2 * _Nd_ull),
"Maximum supported integer size is 128-bit");
constexpr auto __max_ull = numeric_limits<unsigned long long>::max();
unsigned long long __low = __x & __max_ull;
unsigned long long __high = __x >> _Nd_ull;
return __builtin_popcountll(__low) + __builtin_popcountll(__high);
}
}
template<typename _Tp>
constexpr bool
__ispow2(_Tp __x) noexcept
{ return std::__popcount(__x) == 1; }
template<typename _Tp>
constexpr _Tp
__ceil2(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
if (__x == 0 || __x == 1)
return 1;
auto __shift_exponent = _Nd - std::__countl_zero((_Tp)(__x - 1u));
// If the shift exponent equals _Nd then the correct result is not
// representable as a value of _Tp, and so the result is undefined.
// Want that undefined behaviour to be detected in constant expressions,
// by UBSan, and by debug assertions.
#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (!__builtin_is_constant_evaluated())
__glibcxx_assert( __shift_exponent != numeric_limits<_Tp>::digits );
#endif
using __promoted_type = decltype(__x << 1);
if _GLIBCXX17_CONSTEXPR (!is_same<__promoted_type, _Tp>::value)
{
// If __x undergoes integral promotion then shifting by _Nd is
// not undefined. In order to make the shift undefined, so that
// it is diagnosed in constant expressions and by UBsan, we also
// need to "promote" the shift exponent to be too large for the
// promoted type.
const int __extra_exp = sizeof(__promoted_type) / sizeof(_Tp) / 2;
__shift_exponent |= (__shift_exponent & _Nd) << __extra_exp;
}
return (_Tp)1u << __shift_exponent;
}
template<typename _Tp>
constexpr _Tp
__floor2(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
if (__x == 0)
return 0;
return (_Tp)1u << (_Nd - std::__countl_zero((_Tp)(__x >> 1)));
}
template<typename _Tp>
constexpr _Tp
__log2p1(_Tp __x) noexcept
{
constexpr auto _Nd = numeric_limits<_Tp>::digits;
return _Nd - std::__countl_zero(__x);
}
#if __cplusplus > 201703L
template<typename _Tp, typename _Up = _Tp>
using _If_is_unsigned_integer
= enable_if_t<__is_unsigned_integer<_Tp>::value, _Up>;
// [bit.rot], rotating
template<typename _Tp>
[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
rotl(_Tp __x, int __s) noexcept
{ return std::__rotl(__x, __s); }
template<typename _Tp>
[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
rotr(_Tp __x, int __s) noexcept
{ return std::__rotr(__x, __s); }
// [bit.count], counting
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, int>
countl_zero(_Tp __x) noexcept
{ return std::__countl_zero(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, int>
countl_one(_Tp __x) noexcept
{ return std::__countl_one(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, int>
countr_zero(_Tp __x) noexcept
{ return std::__countr_zero(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, int>
countr_one(_Tp __x) noexcept
{ return std::__countr_one(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, int>
popcount(_Tp __x) noexcept
{ return std::__popcount(__x); }
// [bit.pow.two], integral powers of 2
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp, bool>
ispow2(_Tp __x) noexcept
{ return std::__ispow2(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp>
ceil2(_Tp __x) noexcept
{ return std::__ceil2(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp>
floor2(_Tp __x) noexcept
{ return std::__floor2(__x); }
template<typename _Tp>
constexpr _If_is_unsigned_integer<_Tp>
log2p1(_Tp __x) noexcept
{ return std::__log2p1(__x); }
/// Byte order
enum class endian
{
little = __ORDER_LITTLE_ENDIAN__,
big = __ORDER_BIG_ENDIAN__,
native = __BYTE_ORDER__
};
#endif // C++2a
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++14
#endif // _GLIBCXX_BIT
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