[thirdparty/gcc.git] / libstdc++-v3 / include / std / bit

// <bit> -*- C++ -*-

// Copyright (C) 2018-2025 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

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#if __cplusplus >= 201402L

#include <concepts> // for std::integral
#include <type_traits>

#if _GLIBCXX_HOSTED || __has_include(<ext/numeric_traits.h>)
# include <ext/numeric_traits.h>
#else
# include <limits>
/// @cond undocumented
namespace __gnu_cxx
{
  template<typename _Tp>
    struct __int_traits
    {
      static constexpr int __digits = std::numeric_limits<_Tp>::digits;
      static constexpr _Tp __max = std::numeric_limits<_Tp>::max();
    };
}
/// @endcond
#endif

#define __glibcxx_want_bit_cast
#define __glibcxx_want_byteswap
#define __glibcxx_want_bitops
#define __glibcxx_want_int_pow2
#define __glibcxx_want_endian
#include <bits/version.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   * @defgroup bit_manip Bit manipulation
   * @ingroup numerics
   *
   * Utilities for examining and manipulating individual bits.
   *
   * @{
   */

#ifdef __cpp_lib_bit_cast // C++ >= 20

  /// Create a value of type `To` from the bits of `from`.
  /**
   * @tparam _To   A trivially-copyable type.
   * @param __from A trivially-copyable object of the same size as `_To`.
   * @return       An object of type `_To`.
   * @since C++20
   */
  template<typename _To, typename _From>
    [[nodiscard]]
    constexpr _To
    bit_cast(const _From& __from) noexcept
#ifdef __cpp_concepts
    requires (sizeof(_To) == sizeof(_From))
      && is_trivially_copyable_v<_To> && is_trivially_copyable_v<_From>
#endif
    {
      return __builtin_bit_cast(_To, __from);
    }
#endif // __cpp_lib_bit_cast

#ifdef __cpp_lib_byteswap // C++ >= 23

  /// Reverse order of bytes in the object representation of `value`.
  /**
   * @tparam _Tp     An integral type.
   * @param __value  An object of integer type.
   * @return         An object of the same type, with the bytes reversed.
   * @since C++23
   */
  template<integral _Tp>
    [[nodiscard]]
    constexpr _Tp
    byteswap(_Tp __value) noexcept
    {
      if constexpr (sizeof(_Tp) == 1)
	return __value;
#if __cpp_if_consteval >= 202106L && __CHAR_BIT__ == 8
      if !consteval
	{
	  if constexpr (sizeof(_Tp) == 2)
	    return __builtin_bswap16(__value);
	  if constexpr (sizeof(_Tp) == 4)
	    return __builtin_bswap32(__value);
	  if constexpr (sizeof(_Tp) == 8)
	    return __builtin_bswap64(__value);
	  if constexpr (sizeof(_Tp) == 16)
#if __has_builtin(__builtin_bswap128)
	    return __builtin_bswap128(__value);
#else
	    return (__builtin_bswap64(__value >> 64)
		    | (static_cast<_Tp>(__builtin_bswap64(__value)) << 64));
#endif
	}
#endif

      // Fallback implementation that handles even __int24 etc.
      using _Up = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
      size_t __diff = __CHAR_BIT__ * (sizeof(_Tp) - 1);
      _Up __mask1 = static_cast<unsigned char>(~0);
      _Up __mask2 = __mask1 << __diff;
      _Up __val = __value;
      for (size_t __i = 0; __i < sizeof(_Tp) / 2; ++__i)
	{
	  _Up __byte1 = __val & __mask1;
	  _Up __byte2 = __val & __mask2;
	  __val = (__val ^ __byte1 ^ __byte2
		   ^ (__byte1 << __diff) ^ (__byte2 >> __diff));
	  __mask1 <<= __CHAR_BIT__;
	  __mask2 >>= __CHAR_BIT__;
	  __diff -= 2 * __CHAR_BIT__;
	}
      return __val;
    }
#endif // __cpp_lib_byteswap

  /// @cond undocumented
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr

  template<typename _Tp>
    constexpr _Tp
    __rotl(_Tp __x, int __s) noexcept
    {
      constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
      if constexpr ((_Nd & (_Nd - 1)) == 0)
	{
	  // Variant for power of two _Nd which the compiler can
	  // easily pattern match.
	  constexpr unsigned __uNd = _Nd;
	  const auto __r = static_cast<unsigned>(__s);
	  return (__x << (__r % __uNd)) | (__x >> ((-__r) % __uNd));
	}
      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 = __gnu_cxx::__int_traits<_Tp>::__digits;
      if constexpr ((_Nd & (_Nd - 1)) == 0)
	{
	  // Variant for power of two _Nd which the compiler can
	  // easily pattern match.
	  constexpr unsigned __uNd = _Nd;
	  const auto __r = static_cast<unsigned>(__s);
	  return (__x >> (__r % __uNd)) | (__x << ((-__r) % __uNd));
	}
      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
    {
      using __gnu_cxx::__int_traits;
      constexpr auto _Nd = __int_traits<_Tp>::__digits;

#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_clzg)
      return __builtin_clzg(__x, _Nd);
#else
      if (__x == 0)
        return _Nd;

      constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
      constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
      constexpr auto _Nd_u = __int_traits<unsigned>::__digits;

      if constexpr (_Nd <= _Nd_u)
	{
	  constexpr int __diff = _Nd_u - _Nd;
	  return __builtin_clz(__x) - __diff;
	}
      else if constexpr (_Nd <= _Nd_ul)
	{
	  constexpr int __diff = _Nd_ul - _Nd;
	  return __builtin_clzl(__x) - __diff;
	}
      else if 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 = __int_traits<unsigned long long>::__max;
	  unsigned long long __low = __x & __max_ull;
	  return (_Nd - _Nd_ull) + __builtin_clzll(__low);
	}
#endif
    }

  template<typename _Tp>
    constexpr int
    __countl_one(_Tp __x) noexcept
    {
      return std::__countl_zero<_Tp>((_Tp)~__x);
    }

  template<typename _Tp>
    constexpr int
    __countr_zero(_Tp __x) noexcept
    {
      using __gnu_cxx::__int_traits;
      constexpr auto _Nd = __int_traits<_Tp>::__digits;

#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_ctzg)
      return __builtin_ctzg(__x, _Nd);
#else
      if (__x == 0)
        return _Nd;

      constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
      constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
      constexpr auto _Nd_u = __int_traits<unsigned>::__digits;

      if constexpr (_Nd <= _Nd_u)
	return __builtin_ctz(__x);
      else if constexpr (_Nd <= _Nd_ul)
	return __builtin_ctzl(__x);
      else if 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 = __int_traits<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;
	}
#endif
    }

  template<typename _Tp>
    constexpr int
    __countr_one(_Tp __x) noexcept
    {
      return std::__countr_zero((_Tp)~__x);
    }

  template<typename _Tp>
    constexpr int
    __popcount(_Tp __x) noexcept
    {
#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_popcountg)
      return __builtin_popcountg(__x);
#else
      using __gnu_cxx::__int_traits;
      constexpr auto _Nd = __int_traits<_Tp>::__digits;

      constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
      constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
      constexpr auto _Nd_u = __int_traits<unsigned>::__digits;

      if constexpr (_Nd <= _Nd_u)
	return __builtin_popcount(__x);
      else if constexpr (_Nd <= _Nd_ul)
	return __builtin_popcountl(__x);
      else if 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 = __int_traits<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);
	}
#endif
    }

  template<typename _Tp>
    constexpr bool
    __has_single_bit(_Tp __x) noexcept
    { return std::__popcount(__x) == 1; }

  template<typename _Tp>
    constexpr _Tp
    __bit_ceil(_Tp __x) noexcept
    {
      using __gnu_cxx::__int_traits;
      constexpr auto _Nd = __int_traits<_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.
      if (!std::__is_constant_evaluated())
	{
	  __glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
	}

      using __promoted_type = decltype(__x << 1);
      if 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
    __bit_floor(_Tp __x) noexcept
    {
      constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
      if (__x == 0)
        return 0;
      return (_Tp)1u << (_Nd - std::__countl_zero((_Tp)(__x >> 1)));
    }

  template<typename _Tp>
    constexpr int
    __bit_width(_Tp __x) noexcept
    {
      constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
      return _Nd - std::__countl_zero(__x);
    }

#pragma GCC diagnostic pop
  /// @endcond

#ifdef __cpp_lib_bitops // C++ >= 20

  /// @cond undocumented
  template<typename _Tp>
    concept __unsigned_integer = __is_unsigned_integer<_Tp>::value;
  /// @endcond

  // [bit.rot], rotating

  /// Rotate `x` to the left by `s` bits.
  template<__unsigned_integer _Tp>
    [[nodiscard]] constexpr _Tp
    rotl(_Tp __x, int __s) noexcept
    { return std::__rotl(__x, __s); }

  /// Rotate `x` to the right by `s` bits.
  template<__unsigned_integer _Tp>
    [[nodiscard]] constexpr _Tp
    rotr(_Tp __x, int __s) noexcept
    { return std::__rotr(__x, __s); }

  // [bit.count], counting

  /// The number of contiguous zero bits, starting from the highest bit.
  template<__unsigned_integer _Tp>
    constexpr int
    countl_zero(_Tp __x) noexcept
    { return std::__countl_zero(__x); }

  /// The number of contiguous one bits, starting from the highest bit.
  template<__unsigned_integer _Tp>
    constexpr int
    countl_one(_Tp __x) noexcept
    { return std::__countl_one(__x); }

  /// The number of contiguous zero bits, starting from the lowest bit.
  template<__unsigned_integer _Tp>
    constexpr int
    countr_zero(_Tp __x) noexcept
    { return std::__countr_zero(__x); }

  /// The number of contiguous one bits, starting from the lowest bit.
  template<__unsigned_integer _Tp>
    constexpr int
    countr_one(_Tp __x) noexcept
    { return std::__countr_one(__x); }

  /// The number of bits set in `x`.
  template<__unsigned_integer _Tp>
    constexpr int
    popcount(_Tp __x) noexcept
    { return std::__popcount(__x); }
#endif // __cpp_lib_bitops

#ifdef __cpp_lib_int_pow2 // C++ >= 20
  // [bit.pow.two], integral powers of 2

  /// True if `x` is a power of two, false otherwise.
  template<__unsigned_integer _Tp>
    constexpr bool
    has_single_bit(_Tp __x) noexcept
    { return std::__has_single_bit(__x); }

  /// The smallest power-of-two not less than `x`.
  template<__unsigned_integer _Tp>
    constexpr _Tp
    bit_ceil(_Tp __x) noexcept
    { return std::__bit_ceil(__x); }

  /// The largest power-of-two not greater than `x`.
  template<__unsigned_integer _Tp>
    constexpr _Tp
    bit_floor(_Tp __x) noexcept
    { return std::__bit_floor(__x); }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 3656. Inconsistent bit operations returning a count
  /// The smallest integer greater than the base-2 logarithm of `x`.
  template<__unsigned_integer _Tp>
    constexpr int
    bit_width(_Tp __x) noexcept
    { return std::__bit_width(__x); }
#endif // defined (__cpp_lib_int_pow2)

#ifdef __cpp_lib_endian // C++ >= 20

  /// Byte order constants
  /**
   * The platform endianness can be checked by comparing `std::endian::native`
   * to one of `std::endian::big` or `std::endian::little`.
   *
   * @since C++20
   */
  enum class endian
  {
    little = __ORDER_LITTLE_ENDIAN__,
    big    = __ORDER_BIG_ENDIAN__,
    native = __BYTE_ORDER__
  };
#endif // __cpp_lib_endian

  /// @}

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++14
#endif // _GLIBCXX_BIT
Commit	Line	Data
	1	// <bit> -- C++ --
	2
	3	// Copyright (C) 2018-2025 Free Software Foundation, Inc.
	4	//
	5	// This file is part of the GNU ISO C++ Library. This library is free
	6	// software; you can redistribute it and/or modify it under the
	7	// terms of the GNU General Public License as published by the
	8	// Free Software Foundation; either version 3, or (at your option)
	9	// any later version.
	10
	11	// This library is distributed in the hope that it will be useful,
	12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	// GNU General Public License for more details.
	15
	16	// Under Section 7 of GPL version 3, you are granted additional
	17	// permissions described in the GCC Runtime Library Exception, version
	18	// 3.1, as published by the Free Software Foundation.
	19
	20	// You should have received a copy of the GNU General Public License and
	21	// a copy of the GCC Runtime Library Exception along with this program;
	22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
	23	// <http://www.gnu.org/licenses/>.
	24
	25	/** @file include/bit
	26	* This is a Standard C++ Library header.
	27	*/
	28
	29	#ifndef _GLIBCXX_BIT
	30	#define _GLIBCXX_BIT 1
	31
	32	#ifdef _GLIBCXX_SYSHDR
	33	#pragma GCC system_header
	34	#endif
	35
	36	#if __cplusplus >= 201402L
	37
	38	#include <concepts> // for std::integral
	39	#include <type_traits>
	40
	41	#if _GLIBCXX_HOSTED \|\| __has_include(<ext/numeric_traits.h>)
	42	# include <ext/numeric_traits.h>
	43	#else
	44	# include <limits>
	45	/// @cond undocumented
	46	namespace __gnu_cxx
	47	{
	48	template<typename _Tp>
	49	struct __int_traits
	50	{
	51	static constexpr int __digits = std::numeric_limits<_Tp>::digits;
	52	static constexpr _Tp __max = std::numeric_limits<_Tp>::max();
	53	};
	54	}
	55	/// @endcond
	56	#endif
	57
	58	#define __glibcxx_want_bit_cast
	59	#define __glibcxx_want_byteswap
	60	#define __glibcxx_want_bitops
	61	#define __glibcxx_want_int_pow2
	62	#define __glibcxx_want_endian
	63	#include <bits/version.h>
	64
	65	namespace std _GLIBCXX_VISIBILITY(default)
	66	{
	67	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	68
	69	/**
	70	* @defgroup bit_manip Bit manipulation
	71	* @ingroup numerics
	72	*
	73	* Utilities for examining and manipulating individual bits.
	74	*
	75	* @{
	76	*/
	77
	78	#ifdef __cpp_lib_bit_cast // C++ >= 20
	79
	80	/// Create a value of type `To` from the bits of `from`.
	81	/**
	82	* @tparam _To A trivially-copyable type.
	83	* @param __from A trivially-copyable object of the same size as `_To`.
	84	* @return An object of type `_To`.
	85	* @since C++20
	86	*/
	87	template<typename _To, typename _From>
	88	[[nodiscard]]
	89	constexpr _To
	90	bit_cast(const _From& __from) noexcept
	91	#ifdef __cpp_concepts
	92	requires (sizeof(_To) == sizeof(_From))
	93	&& is_trivially_copyable_v<_To> && is_trivially_copyable_v<_From>
	94	#endif
	95	{
	96	return __builtin_bit_cast(_To, __from);
	97	}
	98	#endif // __cpp_lib_bit_cast
	99
	100	#ifdef __cpp_lib_byteswap // C++ >= 23
	101
	102	/// Reverse order of bytes in the object representation of `value`.
	103	/**
	104	* @tparam _Tp An integral type.
	105	* @param __value An object of integer type.
	106	* @return An object of the same type, with the bytes reversed.
	107	* @since C++23
	108	*/
	109	template<integral _Tp>
	110	[[nodiscard]]
	111	constexpr _Tp
	112	byteswap(_Tp __value) noexcept
	113	{
	114	if constexpr (sizeof(_Tp) == 1)
	115	return __value;
	116	#if __cpp_if_consteval >= 202106L && __CHAR_BIT__ == 8
	117	if !consteval
	118	{
	119	if constexpr (sizeof(_Tp) == 2)
	120	return __builtin_bswap16(__value);
	121	if constexpr (sizeof(_Tp) == 4)
	122	return __builtin_bswap32(__value);
	123	if constexpr (sizeof(_Tp) == 8)
	124	return __builtin_bswap64(__value);
	125	if constexpr (sizeof(_Tp) == 16)
	126	#if __has_builtin(__builtin_bswap128)
	127	return __builtin_bswap128(__value);
	128	#else
	129	return (__builtin_bswap64(__value >> 64)
	130	\| (static_cast<_Tp>(__builtin_bswap64(__value)) << 64));
	131	#endif
	132	}
	133	#endif
	134
	135	// Fallback implementation that handles even __int24 etc.
	136	using _Up = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
	137	size_t __diff = __CHAR_BIT__ * (sizeof(_Tp) - 1);
	138	_Up __mask1 = static_cast<unsigned char>(~0);
	139	_Up __mask2 = __mask1 << __diff;
	140	_Up __val = __value;
	141	for (size_t __i = 0; __i < sizeof(_Tp) / 2; ++__i)
	142	{
	143	_Up __byte1 = __val & __mask1;
	144	_Up __byte2 = __val & __mask2;
	145	__val = (__val ^ __byte1 ^ __byte2
	146	^ (__byte1 << __diff) ^ (__byte2 >> __diff));
	147	__mask1 <<= __CHAR_BIT__;
	148	__mask2 >>= __CHAR_BIT__;
	149	__diff -= 2 * __CHAR_BIT__;
	150	}
	151	return __val;
	152	}
	153	#endif // __cpp_lib_byteswap
	154
	155	/// @cond undocumented
	156	#pragma GCC diagnostic push
	157	#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
	158
	159	template<typename _Tp>
	160	constexpr _Tp
	161	__rotl(_Tp __x, int __s) noexcept
	162	{
	163	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
	164	if constexpr ((_Nd & (_Nd - 1)) == 0)
	165	{
	166	// Variant for power of two _Nd which the compiler can
	167	// easily pattern match.
	168	constexpr unsigned __uNd = _Nd;
	169	const auto __r = static_cast<unsigned>(__s);
	170	return (__x << (__r % __uNd)) \| (__x >> ((-__r) % __uNd));
	171	}
	172	const int __r = __s % _Nd;
	173	if (__r == 0)
	174	return __x;
	175	else if (__r > 0)
	176	return (__x << __r) \| (__x >> ((_Nd - __r) % _Nd));
	177	else
	178	return (__x >> -__r) \| (__x << ((_Nd + __r) % _Nd)); // rotr(x, -r)
	179	}
	180
	181	template<typename _Tp>
	182	constexpr _Tp
	183	__rotr(_Tp __x, int __s) noexcept
	184	{
	185	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
	186	if constexpr ((_Nd & (_Nd - 1)) == 0)
	187	{
	188	// Variant for power of two _Nd which the compiler can
	189	// easily pattern match.
	190	constexpr unsigned __uNd = _Nd;
	191	const auto __r = static_cast<unsigned>(__s);
	192	return (__x >> (__r % __uNd)) \| (__x << ((-__r) % __uNd));
	193	}
	194	const int __r = __s % _Nd;
	195	if (__r == 0)
	196	return __x;
	197	else if (__r > 0)
	198	return (__x >> __r) \| (__x << ((_Nd - __r) % _Nd));
	199	else
	200	return (__x << -__r) \| (__x >> ((_Nd + __r) % _Nd)); // rotl(x, -r)
	201	}
	202
	203	template<typename _Tp>
	204	constexpr int
	205	__countl_zero(_Tp __x) noexcept
	206	{
	207	using __gnu_cxx::__int_traits;
	208	constexpr auto _Nd = __int_traits<_Tp>::__digits;
	209
	210	#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_clzg)
	211	return __builtin_clzg(__x, _Nd);
	212	#else
	213	if (__x == 0)
	214	return _Nd;
	215
	216	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	217	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	218	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
	219
	220	if constexpr (_Nd <= _Nd_u)
	221	{
	222	constexpr int __diff = _Nd_u - _Nd;
	223	return __builtin_clz(__x) - __diff;
	224	}
	225	else if constexpr (_Nd <= _Nd_ul)
	226	{
	227	constexpr int __diff = _Nd_ul - _Nd;
	228	return __builtin_clzl(__x) - __diff;
	229	}
	230	else if constexpr (_Nd <= _Nd_ull)
	231	{
	232	constexpr int __diff = _Nd_ull - _Nd;
	233	return __builtin_clzll(__x) - __diff;
	234	}
	235	else // (_Nd > _Nd_ull)
	236	{
	237	static_assert(_Nd <= (2 * _Nd_ull),
	238	"Maximum supported integer size is 128-bit");
	239
	240	unsigned long long __high = __x >> _Nd_ull;
	241	if (__high != 0)
	242	{
	243	constexpr int __diff = (2 * _Nd_ull) - _Nd;
	244	return __builtin_clzll(__high) - __diff;
	245	}
	246	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
	247	unsigned long long __low = __x & __max_ull;
	248	return (_Nd - _Nd_ull) + __builtin_clzll(__low);
	249	}
	250	#endif
	251	}
	252
	253	template<typename _Tp>
	254	constexpr int
	255	__countl_one(_Tp __x) noexcept
	256	{
	257	return std::__countl_zero<_Tp>((_Tp)~__x);
	258	}
	259
	260	template<typename _Tp>
	261	constexpr int
	262	__countr_zero(_Tp __x) noexcept
	263	{
	264	using __gnu_cxx::__int_traits;
	265	constexpr auto _Nd = __int_traits<_Tp>::__digits;
	266
	267	#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_ctzg)
	268	return __builtin_ctzg(__x, _Nd);
	269	#else
	270	if (__x == 0)
	271	return _Nd;
	272
	273	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	274	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	275	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
	276
	277	if constexpr (_Nd <= _Nd_u)
	278	return __builtin_ctz(__x);
	279	else if constexpr (_Nd <= _Nd_ul)
	280	return __builtin_ctzl(__x);
	281	else if constexpr (_Nd <= _Nd_ull)
	282	return __builtin_ctzll(__x);
	283	else // (_Nd > _Nd_ull)
	284	{
	285	static_assert(_Nd <= (2 * _Nd_ull),
	286	"Maximum supported integer size is 128-bit");
	287
	288	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
	289	unsigned long long __low = __x & __max_ull;
	290	if (__low != 0)
	291	return __builtin_ctzll(__low);
	292	unsigned long long __high = __x >> _Nd_ull;
	293	return __builtin_ctzll(__high) + _Nd_ull;
	294	}
	295	#endif
	296	}
	297
	298	template<typename _Tp>
	299	constexpr int
	300	__countr_one(_Tp __x) noexcept
	301	{
	302	return std::__countr_zero((_Tp)~__x);
	303	}
	304
	305	template<typename _Tp>
	306	constexpr int
	307	__popcount(_Tp __x) noexcept
	308	{
	309	#if _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_popcountg)
	310	return __builtin_popcountg(__x);
	311	#else
	312	using __gnu_cxx::__int_traits;
	313	constexpr auto _Nd = __int_traits<_Tp>::__digits;
	314
	315	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	316	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	317	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
	318
	319	if constexpr (_Nd <= _Nd_u)
	320	return __builtin_popcount(__x);
	321	else if constexpr (_Nd <= _Nd_ul)
	322	return __builtin_popcountl(__x);
	323	else if constexpr (_Nd <= _Nd_ull)
	324	return __builtin_popcountll(__x);
	325	else // (_Nd > _Nd_ull)
	326	{
	327	static_assert(_Nd <= (2 * _Nd_ull),
	328	"Maximum supported integer size is 128-bit");
	329
	330	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
	331	unsigned long long __low = __x & __max_ull;
	332	unsigned long long __high = __x >> _Nd_ull;
	333	return __builtin_popcountll(__low) + __builtin_popcountll(__high);
	334	}
	335	#endif
	336	}
	337
	338	template<typename _Tp>
	339	constexpr bool
	340	__has_single_bit(_Tp __x) noexcept
	341	{ return std::__popcount(__x) == 1; }
	342
	343	template<typename _Tp>
	344	constexpr _Tp
	345	__bit_ceil(_Tp __x) noexcept
	346	{
	347	using __gnu_cxx::__int_traits;
	348	constexpr auto _Nd = __int_traits<_Tp>::__digits;
	349	if (__x == 0 \|\| __x == 1)
	350	return 1;
	351	auto __shift_exponent = _Nd - std::__countl_zero((_Tp)(__x - 1u));
	352	// If the shift exponent equals _Nd then the correct result is not
	353	// representable as a value of _Tp, and so the result is undefined.
	354	// Want that undefined behaviour to be detected in constant expressions,
	355	// by UBSan, and by debug assertions.
	356	if (!std::__is_constant_evaluated())
	357	{
	358	__glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
	359	}
	360
	361	using __promoted_type = decltype(__x << 1);
	362	if constexpr (!is_same<__promoted_type, _Tp>::value)
	363	{
	364	// If __x undergoes integral promotion then shifting by _Nd is
	365	// not undefined. In order to make the shift undefined, so that
	366	// it is diagnosed in constant expressions and by UBsan, we also
	367	// need to "promote" the shift exponent to be too large for the
	368	// promoted type.
	369	const int __extra_exp = sizeof(__promoted_type) / sizeof(_Tp) / 2;
	370	__shift_exponent \|= (__shift_exponent & _Nd) << __extra_exp;
	371	}
	372	return (_Tp)1u << __shift_exponent;
	373	}
	374
	375	template<typename _Tp>
	376	constexpr _Tp
	377	__bit_floor(_Tp __x) noexcept
	378	{
	379	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
	380	if (__x == 0)
	381	return 0;
	382	return (_Tp)1u << (_Nd - std::__countl_zero((_Tp)(__x >> 1)));
	383	}
	384
	385	template<typename _Tp>
	386	constexpr int
	387	__bit_width(_Tp __x) noexcept
	388	{
	389	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
	390	return _Nd - std::__countl_zero(__x);
	391	}
	392
	393	#pragma GCC diagnostic pop
	394	/// @endcond
	395
	396	#ifdef __cpp_lib_bitops // C++ >= 20
	397
	398	/// @cond undocumented
	399	template<typename _Tp>
	400	concept __unsigned_integer = __is_unsigned_integer<_Tp>::value;
	401	/// @endcond
	402
	403	// [bit.rot], rotating
	404
	405	/// Rotate `x` to the left by `s` bits.
	406	template<__unsigned_integer _Tp>
	407	[[nodiscard]] constexpr _Tp
	408	rotl(_Tp __x, int __s) noexcept
	409	{ return std::__rotl(__x, __s); }
	410
	411	/// Rotate `x` to the right by `s` bits.
	412	template<__unsigned_integer _Tp>
	413	[[nodiscard]] constexpr _Tp
	414	rotr(_Tp __x, int __s) noexcept
	415	{ return std::__rotr(__x, __s); }
	416
	417	// [bit.count], counting
	418
	419	/// The number of contiguous zero bits, starting from the highest bit.
	420	template<__unsigned_integer _Tp>
	421	constexpr int
	422	countl_zero(_Tp __x) noexcept
	423	{ return std::__countl_zero(__x); }
	424
	425	/// The number of contiguous one bits, starting from the highest bit.
	426	template<__unsigned_integer _Tp>
	427	constexpr int
	428	countl_one(_Tp __x) noexcept
	429	{ return std::__countl_one(__x); }
	430
	431	/// The number of contiguous zero bits, starting from the lowest bit.
	432	template<__unsigned_integer _Tp>
	433	constexpr int
	434	countr_zero(_Tp __x) noexcept
	435	{ return std::__countr_zero(__x); }
	436
	437	/// The number of contiguous one bits, starting from the lowest bit.
	438	template<__unsigned_integer _Tp>
	439	constexpr int
	440	countr_one(_Tp __x) noexcept
	441	{ return std::__countr_one(__x); }
	442
	443	/// The number of bits set in `x`.
	444	template<__unsigned_integer _Tp>
	445	constexpr int
	446	popcount(_Tp __x) noexcept
	447	{ return std::__popcount(__x); }
	448	#endif // __cpp_lib_bitops
	449
	450	#ifdef __cpp_lib_int_pow2 // C++ >= 20
	451	// [bit.pow.two], integral powers of 2
	452
	453	/// True if `x` is a power of two, false otherwise.
	454	template<__unsigned_integer _Tp>
	455	constexpr bool
	456	has_single_bit(_Tp __x) noexcept
	457	{ return std::__has_single_bit(__x); }
	458
	459	/// The smallest power-of-two not less than `x`.
	460	template<__unsigned_integer _Tp>
	461	constexpr _Tp
	462	bit_ceil(_Tp __x) noexcept
	463	{ return std::__bit_ceil(__x); }
	464
	465	/// The largest power-of-two not greater than `x`.
	466	template<__unsigned_integer _Tp>
	467	constexpr _Tp
	468	bit_floor(_Tp __x) noexcept
	469	{ return std::__bit_floor(__x); }
	470
	471	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	472	// 3656. Inconsistent bit operations returning a count
	473	/// The smallest integer greater than the base-2 logarithm of `x`.
	474	template<__unsigned_integer _Tp>
	475	constexpr int
	476	bit_width(_Tp __x) noexcept
	477	{ return std::__bit_width(__x); }
	478	#endif // defined (__cpp_lib_int_pow2)
	479
	480	#ifdef __cpp_lib_endian // C++ >= 20
	481
	482	/// Byte order constants
	483	/**
	484	* The platform endianness can be checked by comparing `std::endian::native`
	485	* to one of `std::endian::big` or `std::endian::little`.
	486	*
	487	* @since C++20
	488	*/
	489	enum class endian
	490	{
	491	little = __ORDER_LITTLE_ENDIAN__,
	492	big = __ORDER_BIG_ENDIAN__,
	493	native = __BYTE_ORDER__
	494	};
	495	#endif // __cpp_lib_endian
	496
	497	/// @}
	498
	499	_GLIBCXX_END_NAMESPACE_VERSION
	500	} // namespace std
	501
	502	#endif // C++14
	503	#endif // _GLIBCXX_BIT