Bit manipulation functions. More...

Enumerations
enum struct	endian { little = __ORDER_LITTLE_ENDIAN__ , big = __ORDER_BIG_ENDIAN__ , native = __BYTE_ORDER__ }
	Indicates the endianness of all scalar types. If all scalar types are little-endian, `endian::native` equals `endian::little`. If all scalar types are big-endian, `endian::native` equals `endian::big`. More...

Functions
template<typename To, typename From> requires detail::bitcastable<To, From>
constexpr auto	bit_cast (From const &src) noexcept -> To
	Obtain a value of type To by reinterpreting the object representation of from. Every bit in the value representation of the returned To object is equal to the corresponding bit in the object representation of from.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	bit_ceil (UInt x) noexcept -> UInt
	Calculates the smallest integral power of two that is not smaller than x. If that value is not representable in UInt, the behavior is undefined. Call to this function is permitted in constant evaluation only if the undefined behavior does not occur.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	bit_floor (UInt x) noexcept -> UInt
	If x is not zero, calculates the largest integral power of two that is not greater than x. If x is zero, returns zero.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	bit_width (UInt x) noexcept -> int
	If x is not zero, calculates the number of bits needed to store the value x, that is, 1+⌊log2(x)⌋. If x is zero, returns zero.

template<integral Int>
constexpr auto	byteswap (Int val) noexcept -> Int
	Reverses the bytes in the given integer value n.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	countl_one (UInt x) noexcept -> int
	Returns the number of consecutive 1 ("one") bits in the value of x, starting from the most significant bit ("left").

template<etl::builtin_unsigned_integer UInt>
constexpr auto	countl_zero (UInt x) noexcept -> int
	Returns the number of consecutive 0 bits in the value of x, starting from the most significant bit ("left").

template<etl::builtin_unsigned_integer UInt>
constexpr auto	countr_one (UInt x) noexcept -> int
	Returns the number of consecutive 1 bits in the value of x, starting from the least significant bit ("right").

template<etl::builtin_unsigned_integer UInt>
constexpr auto	countr_zero (UInt x) noexcept -> int
	Returns the number of consecutive 0 bits in the value of x, starting from the least significant bit ("right").

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>
constexpr auto	flip_bit (UInt word) noexcept -> UInt
	Flip bit at position Pos.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	flip_bit (UInt word, UInt pos) noexcept -> UInt
	Flip bit at position `pos`.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	has_single_bit (UInt x) noexcept -> bool
	Checks if x is an integral power of two.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	popcount (UInt val) noexcept -> int
	Returns the number of 1 bits in the value of x.

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>
constexpr auto	reset_bit (UInt word) noexcept -> UInt
	Reset bit at position Pos.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	reset_bit (UInt word, UInt pos) noexcept -> UInt
	Reset bit at position `pos`.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	rotl (UInt t, int s) noexcept -> UInt
	Computes the result of bitwise left-rotating the value of x by s positions. This operation is also known as a left circular shift.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	rotr (UInt t, int s) noexcept -> UInt
	Computes the result of bitwise right-rotating the value of x by s positions. This operation is also known as a right circular shift.

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>
constexpr auto	set_bit (UInt word) noexcept -> UInt
	Set bit at position `Pos`

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>
constexpr auto	set_bit (UInt word, bool value) noexcept -> UInt
	Set bit at position `Pos` to `value`.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	set_bit (UInt word, UInt pos) noexcept -> UInt
	Set bit at position `pos`.

template<etl::builtin_unsigned_integer UInt>
constexpr auto	set_bit (UInt word, UInt pos, bool value) -> UInt
	Set bit at position `pos` to `value`.

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>
constexpr auto	test_bit (UInt word) noexcept -> bool
	Test bit at position `Pos`

template<etl::builtin_unsigned_integer UInt>
constexpr auto	test_bit (UInt word, UInt pos) noexcept -> bool
	Test bit at position `pos`.

Detailed Description

Bit manipulation functions.

#include <etl/bit.hpp>

bit.hpp

Enumeration Type Documentation

◆ endian

enum struct endian

strong

Indicates the endianness of all scalar types. If all scalar types are little-endian, endian::native equals endian::little. If all scalar types are big-endian, endian::native equals endian::big.

https://en.cppreference.com/w/cpp/types/endian

Enumerator
little
big
native

Function Documentation

◆ bit_cast()

template<typename To, typename From>
requires detail::bitcastable<To, From>

auto bit_cast ( From const & src ) -> To

constexprnoexcept

Obtain a value of type To by reinterpreting the object representation of from. Every bit in the value representation of the returned To object is equal to the corresponding bit in the object representation of from.

The values of padding bits in the returned To object are unspecified. If there is no value of type To corresponding to the value representation produced, the behavior is undefined. If there are multiple such values, which value is produced is unspecified. This overload only participates in overload resolution if sizeof(To) == sizeof(From) and both To and From are TriviallyCopyable types.

https://en.cppreference.com/w/cpp/numeric/bit_cast

◆ bit_ceil()

template<etl::builtin_unsigned_integer UInt>

auto bit_ceil ( UInt x ) -> UInt

nodiscardconstexprnoexcept

Calculates the smallest integral power of two that is not smaller than x. If that value is not representable in UInt, the behavior is undefined. Call to this function is permitted in constant evaluation only if the undefined behavior does not occur.

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: The smallest integral power of two that is not smaller than x.

◆ bit_floor()

template<etl::builtin_unsigned_integer UInt>

auto bit_floor ( UInt x ) -> UInt

nodiscardconstexprnoexcept

If x is not zero, calculates the largest integral power of two that is not greater than x. If x is zero, returns zero.

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: Zero if x is zero; otherwise, the largest integral power of two that is not greater than x.

◆ bit_width()

template<etl::builtin_unsigned_integer UInt>

auto bit_width ( UInt x ) -> int

nodiscardconstexprnoexcept

If x is not zero, calculates the number of bits needed to store the value x, that is, 1+⌊log2(x)⌋. If x is zero, returns zero.

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

◆ byteswap()

template<integral Int>

auto byteswap ( Int val ) -> Int

nodiscardconstexprnoexcept

Reverses the bytes in the given integer value n.

etl::byteswap participates in overload resolution only if Int satisfies integral, i.e., Int is an integer type. The program is ill-formed if Int has padding bits.

https://en.cppreference.com/w/cpp/numeric/byteswap

◆ countl_one()

template<etl::builtin_unsigned_integer UInt>

auto countl_one ( UInt x ) -> int

nodiscardconstexprnoexcept

Returns the number of consecutive 1 ("one") bits in the value of x, starting from the most significant bit ("left").

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: The number of consecutive 1 bits in the value of x, starting from the most significant bit.

◆ countl_zero()

template<etl::builtin_unsigned_integer UInt>

auto countl_zero ( UInt x ) -> int

nodiscardconstexprnoexcept

Returns the number of consecutive 0 bits in the value of x, starting from the most significant bit ("left").

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: The number of consecutive 0 bits in the value of x, starting from the most significant bit.

◆ countr_one()

template<etl::builtin_unsigned_integer UInt>

auto countr_one ( UInt x ) -> int

nodiscardconstexprnoexcept

Returns the number of consecutive 1 bits in the value of x, starting from the least significant bit ("right").

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: The number of consecutive 1 bits in the value of x, starting from the least significant bit.

◆ countr_zero()

template<etl::builtin_unsigned_integer UInt>

auto countr_zero ( UInt x ) -> int

nodiscardconstexprnoexcept

Returns the number of consecutive 0 bits in the value of x, starting from the least significant bit ("right").

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: The number of consecutive 0 bits in the value of x, starting from the least significant bit.

◆ flip_bit() [1/2]

template<etl::size_t Pos, etl::builtin_unsigned_integer UInt>

auto flip_bit ( UInt word ) -> UInt

nodiscardconstexprnoexcept

Flip bit at position Pos.

https://stackoverflow.com/questions/47981/how-to-set-clear-and-toggle-a-single-bit

Note: Non-standard extension

◆ flip_bit() [2/2]

template<etl::builtin_unsigned_integer UInt>

auto flip_bit	(	UInt	word,
		UInt	pos ) -> UInt

nodiscardconstexprnoexcept

Flip bit at position pos.

https://stackoverflow.com/questions/47981/how-to-set-clear-and-toggle-a-single-bit

Precondition: Position pos must be a valid bit-index for UInt

Note: Non-standard extension

◆ has_single_bit()

template<etl::builtin_unsigned_integer UInt>

auto has_single_bit ( UInt x ) -> bool

nodiscardconstexprnoexcept

Checks if x is an integral power of two.

This overload only participates in overload resolution if T is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).

Returns: true if x is an integral power of two; otherwise false.

◆ popcount()

template<etl::builtin_unsigned_integer UInt>

auto popcount ( UInt val ) -> int

nodiscardconstexprnoexcept

Returns the number of 1 bits in the value of x.

This overload only participates in overload resolution if UInt is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).