Popularity
1.7
Declining
Activity
0.0
Stable
8
3
0

Monthly Downloads: 4
Programming language: Elixir
License: MIT License

lfsr alternatives and similar packages

Based on the "Algorithms and Data structures" category.
Alternatively, view lfsr alternatives based on common mentions on social networks and blogs.

Do you think we are missing an alternative of lfsr or a related project?

Add another 'Algorithms and Data structures' Package

README

LFSR

Elixir implementation of a binary Galois Linear Feedback Shift Register.

It can be used to generate out-of-order counters, since a LFSR of size n can generate a sequence of length 2n-1 (without repetitions).

Usage

Add LFSR as a dependency in your mix.exs file.

def deps do
  [{:lfsr, "~> 0.0.2"}]
end

After you are done, run mix deps.get in your shell to fetch and compile LFSR. Start an interactive Elixir shell with iex -S mix.

iex> lfsr = LFSR.new(1, 16)
%LFSR{mask: 46080, state: 1}
iex> lfsr = lfsr |> LFSR.next |> LFSR.next
%LFSR{mask: 46080, state: 23040}
iex> LFSR.state(lfsr)
23040

Usage with Streams

Let's generate a pseudo-random sequence of numbers between 1_000_000 and 9_999_999.

We need a 24-bit LFSR, since with a 23-bit we can only produce a sequence with length 8_388_607.

iex> LFSR.new(5_345_234, 24) \
...> |> Stream.iterate(&LFSR.next/1) \
...> |> Stream.map(&LFSR.state/1) \
...> |> Stream.filter(&(&1 in 1_000_000..9_999_999)) \
...> |> Enum.take(100)
[5345234, 2672617, 6697466, 3348733, 6342207, 9312455, 9930289, 9683736,
 4841868, 2420934, 1210467, 5787404, 2893702, 1446851, 5816952, 2908476,
 1454238, 8610569, 5036226, 2518113, 6658840, 3329420, 1664710, 6002284,
 3001142, 1500571, 5823667, 5315478, 2657739, 6230457, 8111214, 4055607,
 8764486, 4382243, 5397444, 2698722, 1349361, 6890940, 3445470, 1722735,
 8472877, 5001803, 5474889, 7922322, 3961161, 6495314, 3247657, 6316938,
 3158469, 6294641, ...]

Usage with Agents

defmodule PRNG do
  def start_link do
    Agent.start_link(fn -> LFSR.new(5_345_234, 24) end, name: __MODULE__)
  end

  def next do
    Agent.get_and_update(__MODULE__, fn lfsr ->
      lfsr = next_valid(lfsr)
      {lfsr.state, lfsr}
    end)
  end

  defp next_valid(%LFSR{} = lfsr) do
    lfsr = LFSR.next(lfsr)
    if lfsr.state in 1_000_000..9_999_999, do: lfsr, else: next_valid(lfsr)
  end
end
iex> PRNG.start_link
{:ok, #PID<0.101.0>}
iex> PRNG.next
2672617
iex> PRNG.next
6697466

References