utl Namespace Reference

Functions
template<class T, size_t N>
constexpr size_t	countof (T(&)[N])
	Helper to get number of elements in array.
template<class T>
constexpr auto	bit_size ()
	Size of object in terms of bits.
template<class T>
constexpr T	bit_full ()
	Integer with all bits set to 1.
template<class T>
constexpr T	bit_wrap ()
	Wrap around mask for power of two number of bits within given integer type. For example: [ bit_wrap<uint8_t> = 8 - 1 = 0b111 ] [ bit_wrap<uint16_t> = 16 - 1 = 0b1111 ] [ bit_wrap<uint32_t> = 32 - 1 = 0b11111 ].
template<class T>
constexpr auto	bit_shft ()
	Number of bits to fit bit_wrap<T> result, in other words bit width of (sizeof(T) * 8 - 1). For example: [ bit_shft<uint8_t> = bit_width(0b111) = 3 ] [ bit_shft<uint16_t> = bit_width(0b1111) = 4 ] [ bit_shft<uint32_t> = bit_width(0b11111) = 5 ].
template<class T>
constexpr auto	bit_ceil (auto x)
	Round up division by number of bits within given integer type, which sizeof(T) * 8 is power of two.
constexpr unsigned	cntlz (auto x)
	Count leading zeros.
constexpr unsigned	cnttz (auto x)
	Count trailing zeros.
template<class T>
constexpr size_t	words_in_bits (size_t n)
	Get number of words (integers) required to store N bits.
constexpr size_t	bytes_in_bits (size_t n)
	Get number of bytes required to store N bits.
template<class T = unsigned>
constexpr T	bit (int n)
	Make integer with bit at given position.
template<class T>
constexpr bool	get_bit (T x, int n)
	Get n-th bit of an integer.
template<class T>
constexpr void	set_bit (T &x, int n)
	Set n-th bit of an integer.
template<class T>
constexpr void	clr_bit (T &x, int n)
	Clear n-th bit of an integer.
template<class T>
constexpr bool	get_arr_bit (const T *p, unsigned n)
	Get n-th bit in array of words (starting from LSB).
template<class T>
constexpr void	set_arr_bit (T *p, unsigned n)
	Set n-th bit in array of words (starting from LSB).
template<class T>
constexpr void	clr_arr_bit (T *p, unsigned n)
	Clear n-th bit in array of words (starting from LSB).
template<class T, size_t L>
constexpr void	shift_left (T(&x)[L])
	Shift bits left in array of integer elements from least significant bit and considering 0-th byte as the right most. uint16_t example: 0b10000000'11100001 ==> 0b00000001'11000010.

Function Documentation

bit()

template<class T = unsigned>

T utl::bit ( int n )

constexpr

Make integer with bit at given position.

Template Parameters

T	Inetegr type

Parameters

n	Bit position

Returns

Integer with set bit

bit_ceil()

template<class T>

auto utl::bit_ceil ( auto x )

constexpr

Round up division by number of bits within given integer type, which sizeof(T) * 8 is power of two.

Template Parameters

T	Inetegr type

Parameters

x

Dividend

Returns

Quotient

bit_full()

template<class T>

T utl::bit_full ( )

constexpr

Integer with all bits set to 1.

Template Parameters

T	Integer type

Returns

All set integer

bit_shft()

template<class T>

auto utl::bit_shft ( )

constexpr

Number of bits to fit bit_wrap<T> result, in other words bit width of (sizeof(T) * 8 - 1). For example: [ bit_shft<uint8_t> = bit_width(0b111) = 3 ] [ bit_shft<uint16_t> = bit_width(0b1111) = 4 ] [ bit_shft<uint32_t> = bit_width(0b11111) = 5 ].

Template Parameters

T	Integer type

Returns

Number of bits to shift to divide by sizeof(T) * 8

bit_size()

template<class T>

auto utl::bit_size ( )

constexpr

Size of object in terms of bits.

Template Parameters

T	Object type

Returns

Number of bits

bit_wrap()

template<class T>

T utl::bit_wrap ( )

constexpr

Wrap around mask for power of two number of bits within given integer type. For example: [ bit_wrap<uint8_t> = 8 - 1 = 0b111 ] [ bit_wrap<uint16_t> = 16 - 1 = 0b1111 ] [ bit_wrap<uint32_t> = 32 - 1 = 0b11111 ].

Template Parameters

T	Integer type

Returns

Wrap around mask for number of bits

bytes_in_bits()

size_t utl::bytes_in_bits ( size_t n )

constexpr

Get number of bytes required to store N bits.

Parameters

n	Number of bits to store

Returns

Number of bytes

clr_arr_bit()

template<class T>

void utl::clr_arr_bit ( T * p, unsigned n )

constexpr

Clear n-th bit in array of words (starting from LSB).

Template Parameters

T

Word type

Parameters

p	Array of words
n	Index of bit to clear

clr_bit()

template<class T>

void utl::clr_bit ( T & x, int n )

constexpr

Clear n-th bit of an integer.

Template Parameters

T	Integer type

Parameters

x	Integer
n	Bit position from LSB

cntlz()

unsigned utl::cntlz ( auto x )

constexpr

Count leading zeros.

Parameters

x	Unsigned integer argument

Returns

Number of leading zeros

cnttz()

unsigned utl::cnttz ( auto x )

constexpr

Count trailing zeros.

Parameters

x	Unsigned integer argument

Returns

Number of trailing zeros

countof()

template<class T, size_t N>

size_t utl::countof ( T(&) [N] )

constexpr

Helper to get number of elements in array.

Template Parameters

T	Auto-deduced element type
N	Auto-deduced number of elements

Returns

Array size

get_arr_bit()

template<class T>

bool utl::get_arr_bit ( const T * p, unsigned n )

constexpr

Get n-th bit in array of words (starting from LSB).

Template Parameters

T

Word type

Parameters

p	Array of words
n	Index of bit to get

Returns

true if set

get_bit()

template<class T>

bool utl::get_bit ( T x, int n )

constexpr

Get n-th bit of an integer.

Template Parameters

T	Integer type

Parameters

x	Integer
n	Bit position from LSB

Returns

true if set

set_arr_bit()

template<class T>

void utl::set_arr_bit ( T * p, unsigned n )

constexpr

Set n-th bit in array of words (starting from LSB).

Template Parameters

T

Word type

Parameters

p	Array of words
n	Index of bit to set

set_bit()

template<class T>

void utl::set_bit ( T & x, int n )

constexpr

Set n-th bit of an integer.

Template Parameters

T	Integer type

Parameters

x	Integer
n	Bit position from LSB

shift_left()

template<class T, size_t L>

void utl::shift_left ( T(&) x[L] )

constexpr

Shift bits left in array of integer elements from least significant bit and considering 0-th byte as the right most. uint16_t example: 0b10000000'11100001 ==> 0b00000001'11000010.

Template Parameters

T	Integer type
L	Length of array

Parameters

x	Array of integers, nullptr not acceptable!
len	Number of elements

words_in_bits()

template<class T>

size_t utl::words_in_bits ( size_t n )

constexpr

Get number of words (integers) required to store N bits.

Template Parameters

T	Word integer type

Parameters

n	Number of bits to store

Returns

Number of words