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

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

// Copyright (C) 2018-2022 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>

#if _GLIBCXX_HOSTED
# 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

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>
    [[nodiscard]]
    constexpr _To
    bit_cast(const _From& __from) noexcept
    {
      return __builtin_bit_cast(_To, __from);
    }
#endif

#if __cplusplus > 202002L
#define __cpp_lib_byteswap 202110L

  /// Reverse order of bytes in the object representation of `value`.
  template<typename _Tp>
    [[nodiscard]]
    constexpr enable_if_t<is_integral<_Tp>::value, _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

  /// @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.
      if (!std::__is_constant_evaluated())
	{
	  __glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
	}

      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
7adcbafe	3	// Copyright (C) 2018-2022 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>
474cb5a0 JW	37
	38	#if _GLIBCXX_HOSTED
	39	# include <ext/numeric_traits.h>
	40	#else
	41	# include <limits>
	42	/// @cond undocumented
	43	namespace __gnu_cxx
	44	{
	45	template<typename _Tp>
	46	struct __int_traits
	47	{
	48	static constexpr int __digits = std::numeric_limits<_Tp>::digits;
	49	static constexpr _Tp __max = std::numeric_limits<_Tp>::max();
	50	};
	51	}
	52	/// @endcond
	53	#endif
f3e91052 JW	54
	55	namespace std _GLIBCXX_VISIBILITY(default)
	56	{
	57	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	58
27e6c1f4 JW	59	/**
	60	* @defgroup bit_manip Bit manipulation
	61	* @ingroup numerics
	62	*
	63	* Utilities for examining and manipulating individual bits.
	64	*
	65	* @{
	66	*/
	67
9e433b34 JW	68	#if __cplusplus > 201703l && __has_builtin(__builtin_bit_cast)
	69	#define __cpp_lib_bit_cast 201806L
	70
	71	/// Create a value of type `To` from the bits of `from`.
	72	template<typename _To, typename _From>
406f58e1	73	[[nodiscard]]
9e433b34 JW	74	constexpr _To
	75	bit_cast(const _From& __from) noexcept
	76	{
	77	return __builtin_bit_cast(_To, __from);
	78	}
	79	#endif
	80
7393fa8b JJ	81	#if __cplusplus > 202002L
	82	#define __cpp_lib_byteswap 202110L
	83
	84	/// Reverse order of bytes in the object representation of `value`.
	85	template<typename _Tp>
92084a6d	86	[[nodiscard]]
7393fa8b JJ	87	constexpr enable_if_t<is_integral<_Tp>::value, _Tp>
	88	byteswap(_Tp __value) noexcept
	89	{
	90	if constexpr (sizeof(_Tp) == 1)
	91	return __value;
	92	#if __cpp_if_consteval >= 202106L && __CHAR_BIT__ == 8
	93	if !consteval
	94	{
	95	if constexpr (sizeof(_Tp) == 2)
	96	return __builtin_bswap16(__value);
	97	if constexpr (sizeof(_Tp) == 4)
	98	return __builtin_bswap32(__value);
	99	if constexpr (sizeof(_Tp) == 8)
	100	return __builtin_bswap64(__value);
	101	if constexpr (sizeof(_Tp) == 16)
	102	#if __has_builtin(__builtin_bswap128)
	103	return __builtin_bswap128(__value);
	104	#else
	105	return (__builtin_bswap64(__value >> 64)
	106	\| (static_cast<_Tp>(__builtin_bswap64(__value)) << 64));
	107	#endif
	108	}
	109	#endif
	110
	111	// Fallback implementation that handles even __int24 etc.
	112	using _Up = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
	113	size_t __diff = __CHAR_BIT__ * (sizeof(_Tp) - 1);
	114	_Up __mask1 = static_cast<unsigned char>(~0);
	115	_Up __mask2 = __mask1 << __diff;
	116	_Up __val = __value;
	117	for (size_t __i = 0; __i < sizeof(_Tp) / 2; ++__i)
	118	{
	119	_Up __byte1 = __val & __mask1;
	120	_Up __byte2 = __val & __mask2;
	121	__val = (__val ^ __byte1 ^ __byte2
	122	^ (__byte1 << __diff) ^ (__byte2 >> __diff));
	123	__mask1 <<= __CHAR_BIT__;
	124	__mask2 >>= __CHAR_BIT__;
	125	__diff -= 2 * __CHAR_BIT__;
	126	}
	127	return __val;
	128	}
	129	#endif
	130
27e6c1f4 JW	131	/// @cond undoc
27e6c1f4 JW	132
f3e91052 JW	133	template<typename _Tp>
f3e91052 JW	134	constexpr _Tp
f35da524	135	__rotl(_Tp __x, int __s) noexcept
f3e91052	136	{
eb04805b	137	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
84185598 JJ	138	if _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	139	{
	140	// Variant for power of two _Nd which the compiler can
	141	// easily pattern match.
	142	constexpr unsigned __uNd = _Nd;
	143	const unsigned __r = __s;
	144	return (__x << (__r % __uNd)) \| (__x >> ((-__r) % __uNd));
	145	}
f35da524 JW	146	const int __r = __s % _Nd;
	147	if (__r == 0)
	148	return __x;
	149	else if (__r > 0)
	150	return (__x << __r) \| (__x >> ((_Nd - __r) % _Nd));
	151	else
	152	return (__x >> -__r) \| (__x << ((_Nd + __r) % _Nd)); // rotr(x, -r)
f3e91052 JW	153	}
	154
	155	template<typename _Tp>
	156	constexpr _Tp
f35da524	157	__rotr(_Tp __x, int __s) noexcept
f3e91052	158	{
eb04805b	159	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
84185598 JJ	160	if _GLIBCXX17_CONSTEXPR ((_Nd & (_Nd - 1)) == 0)
	161	{
	162	// Variant for power of two _Nd which the compiler can
	163	// easily pattern match.
	164	constexpr unsigned __uNd = _Nd;
	165	const unsigned __r = __s;
	166	return (__x >> (__r % __uNd)) \| (__x << ((-__r) % __uNd));
	167	}
f35da524 JW	168	const int __r = __s % _Nd;
	169	if (__r == 0)
	170	return __x;
	171	else if (__r > 0)
	172	return (__x >> __r) \| (__x << ((_Nd - __r) % _Nd));
	173	else
	174	return (__x << -__r) \| (__x >> ((_Nd + __r) % _Nd)); // rotl(x, -r)
f3e91052 JW	175	}
	176
	177	template<typename _Tp>
	178	constexpr int
	179	__countl_zero(_Tp __x) noexcept
	180	{
eb04805b JW	181	using __gnu_cxx::__int_traits;
eb04805b JW	182	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052 JW	183
f3e91052 JW	184	if (__x == 0)
337dc307	185	return _Nd;
f3e91052	186
eb04805b JW	187	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	188	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	189	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	190
337dc307	191	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	192	{
337dc307	193	constexpr int __diff = _Nd_u - _Nd;
f3e91052 JW	194	return __builtin_clz(__x) - __diff;
f3e91052 JW	195	}
337dc307	196	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	197	{
337dc307	198	constexpr int __diff = _Nd_ul - _Nd;
f3e91052 JW	199	return __builtin_clzl(__x) - __diff;
f3e91052 JW	200	}
337dc307	201	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	202	{
337dc307	203	constexpr int __diff = _Nd_ull - _Nd;
f3e91052 JW	204	return __builtin_clzll(__x) - __diff;
f3e91052 JW	205	}
337dc307	206	else // (_Nd > _Nd_ull)
f3e91052	207	{
337dc307	208	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	209	"Maximum supported integer size is 128-bit");
f3e91052 JW	210
337dc307	211	unsigned long long __high = __x >> _Nd_ull;
f3e91052 JW	212	if (__high != 0)
f3e91052 JW	213	{
337dc307	214	constexpr int __diff = (2 * _Nd_ull) - _Nd;
f3e91052 JW	215	return __builtin_clzll(__high) - __diff;
f3e91052 JW	216	}
eb04805b	217	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307 JW	218	unsigned long long __low = __x & __max_ull;
337dc307 JW	219	return (_Nd - _Nd_ull) + __builtin_clzll(__low);
f3e91052 JW	220	}
	221	}
	222
	223	template<typename _Tp>
	224	constexpr int
	225	__countl_one(_Tp __x) noexcept
	226	{
f3e91052 JW	227	return std::__countl_zero<_Tp>((_Tp)~__x);
	228	}
	229
	230	template<typename _Tp>
	231	constexpr int
	232	__countr_zero(_Tp __x) noexcept
	233	{
eb04805b JW	234	using __gnu_cxx::__int_traits;
eb04805b JW	235	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052 JW	236
f3e91052 JW	237	if (__x == 0)
337dc307	238	return _Nd;
f3e91052	239
eb04805b JW	240	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	241	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	242	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	243
337dc307	244	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	245	return __builtin_ctz(__x);
337dc307	246	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	247	return __builtin_ctzl(__x);
337dc307	248	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	249	return __builtin_ctzll(__x);
337dc307	250	else // (_Nd > _Nd_ull)
f3e91052	251	{
337dc307	252	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	253	"Maximum supported integer size is 128-bit");
f3e91052 JW	254
eb04805b	255	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307	256	unsigned long long __low = __x & __max_ull;
f3e91052 JW	257	if (__low != 0)
f3e91052 JW	258	return __builtin_ctzll(__low);
337dc307 JW	259	unsigned long long __high = __x >> _Nd_ull;
337dc307 JW	260	return __builtin_ctzll(__high) + _Nd_ull;
f3e91052 JW	261	}
	262	}
	263
	264	template<typename _Tp>
	265	constexpr int
	266	__countr_one(_Tp __x) noexcept
	267	{
f3e91052 JW	268	return std::__countr_zero((_Tp)~__x);
	269	}
	270
	271	template<typename _Tp>
	272	constexpr int
	273	__popcount(_Tp __x) noexcept
	274	{
eb04805b JW	275	using __gnu_cxx::__int_traits;
eb04805b JW	276	constexpr auto _Nd = __int_traits<_Tp>::__digits;
f3e91052	277
eb04805b JW	278	constexpr auto _Nd_ull = __int_traits<unsigned long long>::__digits;
	279	constexpr auto _Nd_ul = __int_traits<unsigned long>::__digits;
	280	constexpr auto _Nd_u = __int_traits<unsigned>::__digits;
f3e91052	281
337dc307	282	if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_u)
f3e91052	283	return __builtin_popcount(__x);
337dc307	284	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ul)
f3e91052	285	return __builtin_popcountl(__x);
337dc307	286	else if _GLIBCXX17_CONSTEXPR (_Nd <= _Nd_ull)
f3e91052	287	return __builtin_popcountll(__x);
337dc307	288	else // (_Nd > _Nd_ull)
f3e91052	289	{
337dc307	290	static_assert(_Nd <= (2 * _Nd_ull),
f3e91052 JW	291	"Maximum supported integer size is 128-bit");
f3e91052 JW	292
eb04805b	293	constexpr auto __max_ull = __int_traits<unsigned long long>::__max;
337dc307 JW	294	unsigned long long __low = __x & __max_ull;
337dc307 JW	295	unsigned long long __high = __x >> _Nd_ull;
f3e91052 JW	296	return __builtin_popcountll(__low) + __builtin_popcountll(__high);
	297	}
	298	}
	299
	300	template<typename _Tp>
	301	constexpr bool
9866abe3	302	__has_single_bit(_Tp __x) noexcept
f3e91052 JW	303	{ return std::__popcount(__x) == 1; }
	304
	305	template<typename _Tp>
	306	constexpr _Tp
9866abe3	307	__bit_ceil(_Tp __x) noexcept
f3e91052	308	{
eb04805b JW	309	using __gnu_cxx::__int_traits;
eb04805b JW	310	constexpr auto _Nd = __int_traits<_Tp>::__digits;
2fb17d2d	311	if (__x == 0 \|\| __x == 1)
f3e91052	312	return 1;
281ab2fb JW	313	auto __shift_exponent = _Nd - std::__countl_zero((_Tp)(__x - 1u));
	314	// If the shift exponent equals _Nd then the correct result is not
	315	// representable as a value of _Tp, and so the result is undefined.
	316	// Want that undefined behaviour to be detected in constant expressions,
	317	// by UBSan, and by debug assertions.
74d14778	318	if (!std::__is_constant_evaluated())
3b39526e	319	{
eb04805b	320	__glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
3b39526e	321	}
74d14778	322
281ab2fb JW	323	using __promoted_type = decltype(__x << 1);
	324	if _GLIBCXX17_CONSTEXPR (!is_same<__promoted_type, _Tp>::value)
	325	{
	326	// If __x undergoes integral promotion then shifting by _Nd is
	327	// not undefined. In order to make the shift undefined, so that
	328	// it is diagnosed in constant expressions and by UBsan, we also
	329	// need to "promote" the shift exponent to be too large for the
	330	// promoted type.
	331	const int __extra_exp = sizeof(__promoted_type) / sizeof(_Tp) / 2;
	332	__shift_exponent \|= (__shift_exponent & _Nd) << __extra_exp;
	333	}
	334	return (_Tp)1u << __shift_exponent;
f3e91052 JW	335	}
	336
	337	template<typename _Tp>
	338	constexpr _Tp
9866abe3	339	__bit_floor(_Tp __x) noexcept
f3e91052	340	{
eb04805b	341	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
f3e91052 JW	342	if (__x == 0)
	343	return 0;
	344	return (_Tp)1u << (_Nd - std::__countl_zero((_Tp)(__x >> 1)));
	345	}
	346
	347	template<typename _Tp>
	348	constexpr _Tp
9866abe3	349	__bit_width(_Tp __x) noexcept
f3e91052	350	{
eb04805b	351	constexpr auto _Nd = __gnu_cxx::__int_traits<_Tp>::__digits;
f3e91052 JW	352	return _Nd - std::__countl_zero(__x);
	353	}
	354
27e6c1f4 JW	355	/// @endcond
27e6c1f4 JW	356
f3e91052 JW	357	#if __cplusplus > 201703L
f3e91052 JW	358
0d58d88d JW	359	#define __cpp_lib_bitops 201907L
0d58d88d JW	360
27e6c1f4	361	/// @cond undoc
f3e91052 JW	362	template<typename _Tp, typename _Up = _Tp>
f3e91052 JW	363	using _If_is_unsigned_integer
47f79054	364	= enable_if_t<__is_unsigned_integer<_Tp>::value, _Up>;
27e6c1f4	365	/// @endcond
f3e91052	366
f35da524	367	// [bit.rot], rotating
f3e91052	368
27e6c1f4	369	/// Rotate `x` to the left by `s` bits.
f3e91052	370	template<typename _Tp>
f35da524 JW	371	[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
f35da524 JW	372	rotl(_Tp __x, int __s) noexcept
f3e91052 JW	373	{ return std::__rotl(__x, __s); }
f3e91052 JW	374
27e6c1f4	375	/// Rotate `x` to the right by `s` bits.
f3e91052	376	template<typename _Tp>
f35da524 JW	377	[[nodiscard]] constexpr _If_is_unsigned_integer<_Tp>
f35da524 JW	378	rotr(_Tp __x, int __s) noexcept
f3e91052 JW	379	{ return std::__rotr(__x, __s); }
f3e91052 JW	380
f35da524	381	// [bit.count], counting
f3e91052	382
27e6c1f4	383	/// The number of contiguous zero bits, starting from the highest bit.
f3e91052 JW	384	template<typename _Tp>
	385	constexpr _If_is_unsigned_integer<_Tp, int>
	386	countl_zero(_Tp __x) noexcept
	387	{ return std::__countl_zero(__x); }
	388
27e6c1f4	389	/// The number of contiguous one bits, starting from the highest bit.
f3e91052 JW	390	template<typename _Tp>
	391	constexpr _If_is_unsigned_integer<_Tp, int>
	392	countl_one(_Tp __x) noexcept
	393	{ return std::__countl_one(__x); }
	394
27e6c1f4	395	/// The number of contiguous zero bits, starting from the lowest bit.
f3e91052 JW	396	template<typename _Tp>
	397	constexpr _If_is_unsigned_integer<_Tp, int>
	398	countr_zero(_Tp __x) noexcept
	399	{ return std::__countr_zero(__x); }
	400
27e6c1f4	401	/// The number of contiguous one bits, starting from the lowest bit.
f3e91052 JW	402	template<typename _Tp>
	403	constexpr _If_is_unsigned_integer<_Tp, int>
	404	countr_one(_Tp __x) noexcept
	405	{ return std::__countr_one(__x); }
	406
27e6c1f4	407	/// The number of bits set in `x`.
f3e91052 JW	408	template<typename _Tp>
	409	constexpr _If_is_unsigned_integer<_Tp, int>
	410	popcount(_Tp __x) noexcept
	411	{ return std::__popcount(__x); }
f3e91052	412
f35da524	413	// [bit.pow.two], integral powers of 2
f3e91052	414
9866abe3 JW	415	#define __cpp_lib_int_pow2 202002L
9866abe3 JW	416
27e6c1f4	417	/// True if `x` is a power of two, false otherwise.
f3e91052 JW	418	template<typename _Tp>
f3e91052 JW	419	constexpr _If_is_unsigned_integer<_Tp, bool>
9866abe3 JW	420	has_single_bit(_Tp __x) noexcept
9866abe3 JW	421	{ return std::__has_single_bit(__x); }
f3e91052	422
27e6c1f4	423	/// The smallest power-of-two not less than `x`.
f3e91052 JW	424	template<typename _Tp>
f3e91052 JW	425	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	426	bit_ceil(_Tp __x) noexcept
9866abe3 JW	427	{ return std::__bit_ceil(__x); }
f3e91052	428
27e6c1f4	429	/// The largest power-of-two not greater than `x`.
f3e91052 JW	430	template<typename _Tp>
f3e91052 JW	431	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	432	bit_floor(_Tp __x) noexcept
9866abe3 JW	433	{ return std::__bit_floor(__x); }
f3e91052	434
27e6c1f4	435	/// The smallest integer greater than the base-2 logarithm of `x`.
f3e91052 JW	436	template<typename _Tp>
f3e91052 JW	437	constexpr _If_is_unsigned_integer<_Tp>
9866abe3 JW	438	bit_width(_Tp __x) noexcept
9866abe3 JW	439	{ return std::__bit_width(__x); }
f3e91052	440
a5378f9b JW	441	#define __cpp_lib_endian 201907L
a5378f9b JW	442
45c7215c JW	443	/// Byte order
	444	enum class endian
	445	{
	446	little = __ORDER_LITTLE_ENDIAN__,
	447	big = __ORDER_BIG_ENDIAN__,
	448	native = __BYTE_ORDER__
	449	};
f3e91052 JW	450	#endif // C++2a
f3e91052 JW	451
27e6c1f4 JW	452	/// @}
27e6c1f4 JW	453
f3e91052 JW	454	_GLIBCXX_END_NAMESPACE_VERSION
	455	} // namespace std
	456
	457	#endif // C++14
	458	#endif // _GLIBCXX_BIT