Functions for working with bits and integer bitmasks.
set_bits_count/1 and hamming_distance/2 treat integers as 64-bit
bitmasks: they inspect bits 0 through 63 and ignore higher bits. Negative
integers are interpreted using their lowest 64 two's-complement bits.
The indexed operations are not capped at 64 bits, and to_list/2 uses the
explicit size supplied by the caller.
Summary
Functions
Returns the bit at bit_index in the given integer.
Returns the bitwise Hamming distance between the
given integers int_l and int_r.
Sets the bit at bit_index in integer to bit.
Returns the count of bits set to 1 in the given integer int.
Converts the given integer to a list of bits.
Toggles the bit at bit_index in integer.
Functions
@spec bit_at(integer(), non_neg_integer()) :: 0 | 1
Returns the bit at bit_index in the given integer.
Examples
iex> Abit.Bitmask.bit_at(2, 0)
0
iex> Abit.Bitmask.bit_at(2, 1)
1
iex> Abit.Bitmask.bit_at(1, 0)
1
iex> Abit.Bitmask.bit_at(0, 0)
0@spec hamming_distance(integer(), integer()) :: non_neg_integer()
Returns the bitwise Hamming distance between the
given integers int_l and int_r.
The distance covers only the lowest 64 bits. Bits above bit 63 are ignored, and negative integers are interpreted using their lowest 64 two's-complement bits.
Examples
iex> Abit.Bitmask.hamming_distance(1, 1)
0
iex> Abit.Bitmask.hamming_distance(1, 0)
1
iex> Abit.Bitmask.hamming_distance(1, 1023)
9
iex> Abit.Bitmask.hamming_distance(1, 1024)
2@spec set_bit_at(integer(), non_neg_integer(), 0 | 1) :: integer()
Sets the bit at bit_index in integer to bit.
Examples
iex> Abit.Bitmask.set_bit_at(1, 0, 0)
0
iex> Abit.Bitmask.set_bit_at(0, 0, 1)
1
iex> Abit.Bitmask.set_bit_at(0, 2, 1)
4@spec set_bits_count(integer()) :: non_neg_integer()
Returns the count of bits set to 1 in the given integer int.
Only the lowest 64 bits are counted. Bits above bit 63 are ignored, and negative integers are interpreted using their lowest 64 two's-complement bits.
Examples
iex> Abit.Bitmask.set_bits_count(3)
2
iex> Abit.Bitmask.set_bits_count(0)
0
iex> Abit.Bitmask.set_bits_count(1024)
1
iex> Abit.Bitmask.set_bits_count(1023)
10@spec to_list(integer(), pos_integer()) :: [0 | 1]
Converts the given integer to a list of bits.
size specifies the bitstring size to use before converting the integer
to a list.
Examples
iex> Abit.Bitmask.to_list(1, 1)
[1]
iex> Abit.Bitmask.to_list(1, 2)
[0, 1]
iex> Abit.Bitmask.to_list(214311324231232211111, 64)
[1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1]@spec toggle_bit_at(integer(), non_neg_integer()) :: integer()
Toggles the bit at bit_index in integer.
Examples
iex> Abit.Bitmask.toggle_bit_at(1, 0)
0
iex> Abit.Bitmask.toggle_bit_at(0, 0)
1
iex> Abit.Bitmask.toggle_bit_at(1, 2)
5