Specs

keep(prefix(), non_neg_integer()) :: prefix()

Keeps count msb bits of given pfx.

If count exceeds the actual number of bits in pfx.bits, it keeps all bits.

Examples

iex> keep("2001:0db8:85a3:0000:0000:8a2e:0370:7334", 64)
"2001:db8:85a3::/64"

iex> keep("1.2.3.0/31", 30)
"1.2.3.0/30"

iex> keep("1.2.3.2/31", 30)
"1.2.3.0/30"

iex> keep("1.2.3.128/25", 24)
"1.2.3.0/24"

iex> keep("1.2.3.0/24", 512)
"1.2.3.0/24"

iex> keep({1, 2, 3, 4}, 24)
{1, 2, 3, 0}

iex> keep({{1, 2, 3, 4}, 32}, 16)
{{1, 2, 0, 0}, 16}

iex> keep(%Pfx{bits: <<1, 2, 3, 4>>, maxlen: 32}, 16)
%Pfx{bits: <<1, 2>>, maxlen: 32}