bit_utils

Erlang functions operating on bits. Indexes of bits in byte numbers start at position 0.

Examples

set_bits/2

Create integer of given size that has specific bits set when represented in binary.

1> bit_utils:set_bits([0,3,5,7], 8).
{ok,149}
2> 2#10010101.
149

bits_set/2

Return indexes of set bits in integer of given size.

1> N = 2#00100110.
38
2> bit_utils:bits_set(N, 8).
{ok,[2,5,6]}

lowest_bit_set/1

Return index of lowest bit set (or atom undefined if none is set).

1> bit_utils:lowest_bit_set(5).
0
2> bit_utils:lowest_bit_set(4).
2
3> bit_utils:lowest_bit_set(0).
undefined

bytes_to_bits/1, bits_to_bytes/1

Count number of bits in bytes and number of bytes that are needed for set of bits.

1> bit_utils:bytes_to_bits(6).
48
2> bit_utils:bits_to_bytes(12).
2

rest_of_byte_size_alignment/1

Get rest number of bits when aligned to a byte i.e. how many additional bits are needed to align to the byte.

1> bit_utils:rest_of_byte_size_alignment(8).
0
2> bit_utils:rest_of_byte_size_alignment(5).
3