Specs

bits(prefix(), [{integer(), integer()}]) :: bitstring()

Returns the concatenation of 1 or more series of bits of the given pfx.

Examples

iex> bits("1.2.3.4", [{0, 8}, {-1, -8}])
<<1, 4>>

iex> bits("1.2.3.0/24", [{0, 8}, {-1, -8}])
<<1, 0>>

iex> bits({1, 2, 3, 4}, [{0, 8}, {-1, -8}])
<<1, 4>>

iex> bits({{1, 2, 3, 0}, 24}, [{0,8}, {-1, -8}])
<<1, 0>>

iex> bits(%Pfx{bits: <<1, 2, 3, 4>>, maxlen: 32}, [{0,8}, {-1, -8}])
<<1, 4>>

Specs

bits(prefix(), integer(), integer()) :: bitstring()

Returns length bits, starting at position for given pfx.

Negative position's are relative to the end of the pfx.bits bitstring, while negative length will collect bits going left instead of to the right. Note that the bit at given position is always included in the result regardless of direction. Finally, a length of 0 results in an empty bitstring.

Examples

# last two bytes
iex> bits("128.0.128.1", 16, 16)
<<128, 1>>

iex> bits({128, 0, 128, 1}, 16, 16) # same
<<128, 1>>

iex> bits({128, 0, 128, 1}, 31, -16) # same
<<128, 1>>

iex> bits({{128, 0, 128, 1}, 32}, 31, -16) # same
<<128, 1>>

# first byte
iex> bits(%Pfx{bits: <<128, 0, 0, 1>>, maxlen: 32}, 0, 8)
<<128>>

# same as
iex> bits(%Pfx{bits: <<128, 0, 0, 1>>, maxlen: 32}, 7, -8)
<<128>>

# missing bits are filled in as `0`
iex> x = new(<<128>>, 32)
iex> bits(x, 0, 32)
<<128, 0, 0, 0>>

iex> x = new(<<128>>, 32)
iex> bits(x, 0, 16)
<<128, 0>>

iex> x = new(<<128>>, 32)
iex> bits(x, 15, -16)
<<128, 0>>

# the last 5 bits
iex> x = new(<<255>>, 32)
iex> bits(x, 7, -5)
<<0b11111::size(5)>>