Standard library header <bit> (C++20)

This header is part of the general utilities library, and provides facilities to access, process and manipulate both individual bits and bit sequences.

Types
endian (C++20)	indicates the endianness of scalar types (enum)
Functions
bit_cast (C++20)	reinterpret the object representation of one type as that of another (function template)
byteswap (C++23)	reverses the bytes in the given integer value (function template)
has_single_bit (C++20)	checks if a number is an integral power of 2 (function template)
bit_ceil (C++20)	finds the smallest integral power of 2 not less than the given value (function template)
bit_floor (C++20)	finds the largest integral power of 2 not greater than the given value (function template)
bit_width (C++20)	finds the smallest number of bits needed to represent the given value (function template)
shl (C++29)	shifts to the left without the possibility of undefined behavior (function template)
shr (C++29)	shifts to the right without the possibility of undefined behavior (function template)
rotl (C++20)	computes the result of bitwise left-rotation (function template)
rotr (C++20)	computes the result of bitwise right-rotation (function template)
countl_zero (C++20)	counts the number of consecutive 0 bits, starting from the most significant bit (function template)
countl_one (C++20)	counts the number of consecutive 1 bits, starting from the most significant bit (function template)
countr_zero (C++20)	counts the number of consecutive 0 bits, starting from the least significant bit (function template)
countr_one (C++20)	counts the number of consecutive 1 bits, starting from the least significant bit (function template)
popcount (C++20)	counts the number of 1 bits in an unsigned integer (function template)
bit_reverse (C++29)	reverses the bits in an integer (function template)
bit_repeat (C++29)	repeats/broadcasts a bit pattern of specified length (function template)
bit_compress (C++29)	compresses bits of an operand using a mask (PEXT) (function template)
bit_expand (C++29)	expands bits from an operand using a mask (PDEP) (function template)

Synopsis

namespace std {
  // bit_cast
  template<class To, class From>
    constexpr To bit_cast(const From& from) noexcept;

  // byteswap
  template <class T>
    constexpr T byteswap(T value) noexcept;

  // integral powers of 2
  template<class T>
    constexpr bool has_single_bit(T x) noexcept;
  template<class T>
    constexpr T bit_ceil(T x);
  template<class T>
    constexpr T bit_floor(T x) noexcept;
  template<class T>
    constexpr int bit_width(T x) noexcept;

  // shifting
  template<class T, class S>
    constexpr T shl(T x, S s) noexcept;
  template<class T, class S>
    constexpr T shr(T x, S s) noexcept;

  // rotating
  template<class T>
    constexpr T rotl(T x, int s) noexcept;
  template<class T>
    constexpr T rotr(T x, int s) noexcept;

  // counting
  template<class T>
    constexpr int countl_zero(T x) noexcept;
  template<class T>
    constexpr int countl_one(T x) noexcept;
  template<class T>
    constexpr int countr_zero(T x) noexcept;
  template<class T>
    constexpr int countr_one(T x) noexcept;
  template<class T>
    constexpr int popcount(T x) noexcept;

  // permutation
  template<class T>
    constexpr T bit_reverse(T x) noexcept;
  template<class T>
    constexpr T bit_repeat(T x, int l);
  template<class T>
    constexpr T bit_compress(T x, T m) noexcept;
  template<class T>
    constexpr T bit_expand(T x, T m) noexcept;

  // endian
  enum class endian {
    little = /* see description */,
    big    = /* see description */,
    native = /* see description */
  };
}