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

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

// Copyright (C) 2018-2021 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 <ext/numeric_traits.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

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

#if __cplusplus > 201703l && __has_builtin(__builtin_bit_cast)
#define __cpp_lib_bit_cast 201806L

  /// Create a value of type `To` from the bits of `from`.
  template<typename _To, typename _From>
    constexpr _To
    bit_cast(const _From& __from) noexcept
    {
      return __builtin_bit_cast(_To, __from);
    }
#endif

  /// @cond undoc

  template<typename _Tp>
    constexpr _Tp
    __rotl(_Tp __x, int __s) noexcept
    {
      constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
      if _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	{
	  // Variant for power of two _Nd which the compiler can
	  // easily pattern match.
	  constexpr unsigned __uNd = _Nd;
	  const unsigned __r = __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 _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	{
	  // Variant for power of two _Nd which the compiler can
	  // easily pattern match.
	  constexpr unsigned __uNd = _Nd;
	  const unsigned __r = __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 (__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 _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 = __int_traits<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
    {
      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 (__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 _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 = __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;
	}
    }

  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
    {
      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 _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 = __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);
	}
    }

  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.
#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
      if (!__builtin_is_constant_evaluated())
	{
	  __glibcxx_assert( __shift_exponent != __int_traits<_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
    __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 _Tp
    __bit_width(_Tp __x) noexcept
    {
      constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
      return _Nd - std::__countl_zero(__x);
    }

  /// @endcond

#if __cplusplus > 201703L

#define __cpp_lib_bitops 201907L

  /// @cond undoc
  template<typename _Tp, typename _Up = _Tp>
    using _If_is_unsigned_integer
      = enable_if_t<__is_unsigned_integer<_Tp>::value, _Up>;
  /// @endcond

  // [bit.rot], rotating

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

  /// Rotate `x` to the right by `s` bits.
  template<typename _Tp>
    [[nodiscard]] constexpr _If_is_unsigned_integer<_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<typename _Tp>
    constexpr _If_is_unsigned_integer<_Tp, int>
    countl_zero(_Tp __x) noexcept
    { return std::__countl_zero(__x); }

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

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

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

  /// The number of bits set in `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

#define __cpp_lib_int_pow2 202002L

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

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

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

  /// The smallest integer greater than the base-2 logarithm of `x`.
  template<typename _Tp>
    constexpr _If_is_unsigned_integer<_Tp>
    bit_width(_Tp __x) noexcept
    { return std::__bit_width(__x); }

#define __cpp_lib_endian 201907L

  /// 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
Commit	Line	Data
f3e91052 JW	1	// <bit> -- C++ --
f3e91052 JW	2
99dee823	3	// Copyright (C) 2018-2021 Free Software Foundation, Inc.
f3e91052 JW	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	#pragma GCC system_header
	33
	34	#if __cplusplus >= 201402L
	35
	36	#include <type_traits>
eb04805b	37	#include <ext/numeric_traits.h>
f3e91052 JW	38
	39	namespace std _GLIBCXX_VISIBILITY(default)
	40	{
	41	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	42
27e6c1f4 JW	43	/**
	44	* @defgroup bit_manip Bit manipulation
	45	* @ingroup numerics
	46	*
	47	* Utilities for examining and manipulating individual bits.
	48	*
	49	* @{
	50	*/
	51
9e433b34 JW	52	#if __cplusplus > 201703l && __has_builtin(__builtin_bit_cast)
	53	#define __cpp_lib_bit_cast 201806L
	54
	55	/// Create a value of type `To` from the bits of `from`.
	56	template<typename _To, typename _From>
	57	constexpr _To
	58	bit_cast(const _From& __from) noexcept
	59	{
	60	return __builtin_bit_cast(_To, __from);
	61	}
	62	#endif
	63
27e6c1f4 JW	64	/// @cond undoc
27e6c1f4 JW	65
f3e91052 JW	66	template<typename _Tp>
f3e91052 JW	67	constexpr _Tp
f35da524	68	__rotl(_Tp __x, int __s) noexcept
f3e91052	69	{
eb04805b	70	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
84185598 JJ	71	if _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	72	{
	73	// Variant for power of two _Nd which the compiler can
	74	// easily pattern match.
	75	constexpr unsigned __uNd = _Nd;
	76	const unsigned __r = __s;
	77	return (__x << (__r % __uNd)) \| (__x >> ((-__r) % __uNd));
	78	}
f35da524 JW	79	const int __r = __s % _Nd;
	80	if (__r == 0)
	81	return __x;
	82	else if (__r > 0)
	83	return (__x << __r) \| (__x >> ((_Nd - __r) % _Nd));
	84	else
	85	return (__x >> -__r) \| (__x << ((_Nd + __r) % _Nd)); // rotr(x, -r)
f3e91052 JW	86	}
	87
	88	template<typename _Tp>
	89	constexpr _Tp
f35da524	90	__rotr(_Tp __x, int __s) noexcept
f3e91052	91	{
eb04805b	92	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
84185598 JJ	93	if _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	94	{
	95	// Variant for power of two _Nd which the compiler can
	96	// easily pattern match.
	97	constexpr unsigned __uNd = _Nd;
	98	const unsigned __r = __s;
	99	return (__x >> (__r % __uNd)) \| (__x << ((-__r) % __uNd));
	100	}
f35da524 JW	101	const int __r = __s % _Nd;
	102	if (__r == 0)
	103	return __x;
	104	else if (__r > 0)
	105	return (__x >> __r) \| (__x << ((_Nd - __r) % _Nd));
	106	else
	107	return (__x << -__r) \| (__x >> ((_Nd + __r) % _Nd)); // rotl(x, -r)
f3e91052 JW	108	}
	109
	110	template<typename _Tp>
	111	constexpr int
	112	__countl_zero(_Tp __x) noexcept
	113	{
eb04805b JW	114	using __gnu_cxx::__int_traits;
eb04805b JW	115	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052 JW	116
f3e91052 JW	117	if (__x == 0)
337dc307	118	return _Nd;
f3e91052	119
eb04805b JW	120	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	121	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	122	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	123
337dc307	124	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	125	{
337dc307	126	constexpr int __diff = _Nd_u - _Nd;
f3e91052 JW	127	return __builtin_clz(__x) - __diff;
f3e91052 JW	128	}
337dc307	129	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	130	{
337dc307	131	constexpr int __diff = _Nd_ul - _Nd;
f3e91052 JW	132	return __builtin_clzl(__x) - __diff;
f3e91052 JW	133	}
337dc307	134	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	135	{
337dc307	136	constexpr int __diff = _Nd_ull - _Nd;
f3e91052 JW	137	return __builtin_clzll(__x) - __diff;
f3e91052 JW	138	}
337dc307	139	else // (_Nd > _Nd_ull)
f3e91052	140	{
337dc307	141	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	142	"Maximum supported integer size is 128-bit");
f3e91052 JW	143
337dc307	144	unsigned long long __high = __x >> _Nd_ull;
f3e91052 JW	145	if (__high != 0)
f3e91052 JW	146	{
337dc307	147	constexpr int __diff = (2 * _Nd_ull) - _Nd;
f3e91052 JW	148	return __builtin_clzll(__high) - __diff;
f3e91052 JW	149	}
eb04805b	150	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307 JW	151	unsigned long long __low = __x & __max_ull;
337dc307 JW	152	return (_Nd - _Nd_ull) + __builtin_clzll(__low);
f3e91052 JW	153	}
	154	}
	155
	156	template<typename _Tp>
	157	constexpr int
	158	__countl_one(_Tp __x) noexcept
	159	{
f3e91052 JW	160	return std::__countl_zero<_Tp>((_Tp)~__x);
	161	}
	162
	163	template<typename _Tp>
	164	constexpr int
	165	__countr_zero(_Tp __x) noexcept
	166	{
eb04805b JW	167	using __gnu_cxx::__int_traits;
eb04805b JW	168	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052 JW	169
f3e91052 JW	170	if (__x == 0)
337dc307	171	return _Nd;
f3e91052	172
eb04805b JW	173	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	174	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	175	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	176
337dc307	177	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	178	return __builtin_ctz(__x);
337dc307	179	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	180	return __builtin_ctzl(__x);
337dc307	181	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	182	return __builtin_ctzll(__x);
337dc307	183	else // (_Nd > _Nd_ull)
f3e91052	184	{
337dc307	185	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	186	"Maximum supported integer size is 128-bit");
f3e91052 JW	187
eb04805b	188	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307	189	unsigned long long __low = __x & __max_ull;
f3e91052 JW	190	if (__low != 0)
f3e91052 JW	191	return __builtin_ctzll(__low);
337dc307 JW	192	unsigned long long __high = __x >> _Nd_ull;
337dc307 JW	193	return __builtin_ctzll(__high) + _Nd_ull;
f3e91052 JW	194	}
	195	}
	196
	197	template<typename _Tp>
	198	constexpr int
	199	__countr_one(_Tp __x) noexcept
	200	{
f3e91052 JW	201	return std::__countr_zero((_Tp)~__x);
	202	}
	203
	204	template<typename _Tp>
	205	constexpr int
	206	__popcount(_Tp __x) noexcept
	207	{
eb04805b JW	208	using __gnu_cxx::__int_traits;
eb04805b JW	209	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052	210
eb04805b JW	211	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	212	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	213	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	214
337dc307	215	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	216	return __builtin_popcount(__x);
337dc307	217	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	218	return __builtin_popcountl(__x);
337dc307	219	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	220	return __builtin_popcountll(__x);
337dc307	221	else // (_Nd > _Nd_ull)
f3e91052	222	{
337dc307	223	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	224	"Maximum supported integer size is 128-bit");
f3e91052 JW	225
eb04805b	226	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307 JW	227	unsigned long long __low = __x & __max_ull;
337dc307 JW	228	unsigned long long __high = __x >> _Nd_ull;
f3e91052 JW	229	return __builtin_popcountll(__low) + __builtin_popcountll(__high);
	230	}
	231	}
	232
	233	template<typename _Tp>
	234	constexpr bool
9866abe3	235	__has_single_bit(_Tp __x) noexcept
f3e91052 JW	236	{ return std::__popcount(__x) == 1; }
	237
	238	template<typename _Tp>
	239	constexpr _Tp
9866abe3	240	__bit_ceil(_Tp __x) noexcept
f3e91052	241	{
eb04805b JW	242	using __gnu_cxx::__int_traits;
eb04805b JW	243	constexpr auto _Nd = __int_traits<_Tp>::__digits;
2fb17d2d	244	if (__x == 0 \|\| __x == 1)
f3e91052	245	return 1;
281ab2fb JW	246	auto __shift_exponent = _Nd - std::__countl_zero((_Tp)(__x - 1u));
	247	// If the shift exponent equals _Nd then the correct result is not
	248	// representable as a value of _Tp, and so the result is undefined.
	249	// Want that undefined behaviour to be detected in constant expressions,
	250	// by UBSan, and by debug assertions.
	251	#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
	252	if (!__builtin_is_constant_evaluated())
3b39526e	253	{
eb04805b	254	__glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
3b39526e	255	}
281ab2fb JW	256	#endif
	257	using __promoted_type = decltype(__x << 1);
	258	if _GLIBCXX17_CONSTEXPR (!is_same<__promoted_type, _Tp>::value)
	259	{
	260	// If __x undergoes integral promotion then shifting by _Nd is
	261	// not undefined. In order to make the shift undefined, so that
	262	// it is diagnosed in constant expressions and by UBsan, we also
	263	// need to "promote" the shift exponent to be too large for the
	264	// promoted type.
	265	const int __extra_exp = sizeof(__promoted_type) / sizeof(_Tp) / 2;
	266	__shift_exponent \|= (__shift_exponent & _Nd) << __extra_exp;
	267	}
	268	return (_Tp)1u << __shift_exponent;
f3e91052 JW	269	}
	270
	271	template<typename _Tp>
	272	constexpr _Tp
9866abe3	273	__bit_floor(_Tp __x) noexcept
f3e91052	274	{
eb04805b	275	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
f3e91052 JW	276	if (__x == 0)
	277	return 0;
	278	return (_Tp)1u << (_Nd - std::__countl_zero((_Tp)(__x >> 1)));
	279	}
	280
	281	template<typename _Tp>
	282	constexpr _Tp
9866abe3	283	__bit_width(_Tp __x) noexcept
f3e91052	284	{
eb04805b	285	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
f3e91052 JW	286	return _Nd - std::__countl_zero(__x);
	287	}
	288
27e6c1f4 JW	289	/// @endcond
27e6c1f4 JW	290
f3e91052 JW	291	#if __cplusplus > 201703L
f3e91052 JW	292
0d58d88d JW	293	#define __cpp_lib_bitops 201907L
0d58d88d JW	294
27e6c1f4	295	/// @cond undoc
f3e91052 JW	296	template<typename _Tp, typename _Up = _Tp>
f3e91052 JW	297	using _If_is_unsigned_integer
47f79054	298	= enable_if_t<__is_unsigned_integer<_Tp>::value, _Up>;
27e6c1f4	299	/// @endcond
f3e91052	300
f35da524	301	// [bit.rot], rotating
f3e91052	302
27e6c1f4	303	/// Rotate `x` to the left by `s` bits.
f3e91052	304	template<typename _Tp>
f35da524 JW	305	[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
f35da524 JW	306	rotl(_Tp __x, int __s) noexcept
f3e91052 JW	307	{ return std::__rotl(__x, __s); }
f3e91052 JW	308
27e6c1f4	309	/// Rotate `x` to the right by `s` bits.
f3e91052	310	template<typename _Tp>
f35da524 JW	311	[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
f35da524 JW	312	rotr(_Tp __x, int __s) noexcept
f3e91052 JW	313	{ return std::__rotr(__x, __s); }
f3e91052 JW	314
f35da524	315	// [bit.count], counting
f3e91052	316
27e6c1f4	317	/// The number of contiguous zero bits, starting from the highest bit.
f3e91052 JW	318	template<typename _Tp>
	319	constexpr _If_is_unsigned_integer<_Tp, int>
	320	countl_zero(_Tp __x) noexcept
	321	{ return std::__countl_zero(__x); }
	322
27e6c1f4	323	/// The number of contiguous one bits, starting from the highest bit.
f3e91052 JW	324	template<typename _Tp>
	325	constexpr _If_is_unsigned_integer<_Tp, int>
	326	countl_one(_Tp __x) noexcept
	327	{ return std::__countl_one(__x); }
	328
27e6c1f4	329	/// The number of contiguous zero bits, starting from the lowest bit.
f3e91052 JW	330	template<typename _Tp>
	331	constexpr _If_is_unsigned_integer<_Tp, int>
	332	countr_zero(_Tp __x) noexcept
	333	{ return std::__countr_zero(__x); }
	334
27e6c1f4	335	/// The number of contiguous one bits, starting from the lowest bit.
f3e91052 JW	336	template<typename _Tp>
	337	constexpr _If_is_unsigned_integer<_Tp, int>
	338	countr_one(_Tp __x) noexcept
	339	{ return std::__countr_one(__x); }
	340
27e6c1f4	341	/// The number of bits set in `x`.
f3e91052 JW	342	template<typename _Tp>
	343	constexpr _If_is_unsigned_integer<_Tp, int>
	344	popcount(_Tp __x) noexcept
	345	{ return std::__popcount(__x); }
f3e91052	346
f35da524	347	// [bit.pow.two], integral powers of 2
f3e91052	348
9866abe3 JW	349	#define __cpp_lib_int_pow2 202002L
9866abe3 JW	350
27e6c1f4	351	/// True if `x` is a power of two, false otherwise.
f3e91052 JW	352	template<typename _Tp>
f3e91052 JW	353	constexpr _If_is_unsigned_integer<_Tp, bool>
9866abe3 JW	354	has_single_bit(_Tp __x) noexcept
9866abe3 JW	355	{ return std::__has_single_bit(__x); }
f3e91052	356
27e6c1f4	357	/// The smallest power-of-two not less than `x`.
f3e91052 JW	358	template<typename _Tp>
f3e91052 JW	359	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	360	bit_ceil(_Tp __x) noexcept
9866abe3 JW	361	{ return std::__bit_ceil(__x); }
f3e91052	362
27e6c1f4	363	/// The largest power-of-two not greater than `x`.
f3e91052 JW	364	template<typename _Tp>
f3e91052 JW	365	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	366	bit_floor(_Tp __x) noexcept
9866abe3 JW	367	{ return std::__bit_floor(__x); }
f3e91052	368
27e6c1f4	369	/// The smallest integer greater than the base-2 logarithm of `x`.
f3e91052 JW	370	template<typename _Tp>
f3e91052 JW	371	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	372	bit_width(_Tp __x) noexcept
9866abe3 JW	373	{ return std::__bit_width(__x); }
f3e91052	374
a5378f9b JW	375	#define __cpp_lib_endian 201907L
a5378f9b JW	376
45c7215c JW	377	/// Byte order
	378	enum class endian
	379	{
	380	little = __ORDER_LITTLE_ENDIAN__,
	381	big = __ORDER_BIG_ENDIAN__,
	382	native = __BYTE_ORDER__
	383	};
f3e91052 JW	384	#endif // C++2a
f3e91052 JW	385
27e6c1f4 JW	386	/// @}
27e6c1f4 JW	387
f3e91052 JW	388	_GLIBCXX_END_NAMESPACE_VERSION
	389	} // namespace std
	390
	391	#endif // C++14
	392	#endif // _GLIBCXX_BIT