#algorithm #networking #erasure #fountain #code

bin+lib onlinecode

An implementation of "Online Codes", a type of Fountain Code

2 releases

0.1.1 Sep 6, 2021
0.1.0 Jul 4, 2021

#1272 in Algorithms

GPL-2.0-or-later OR LGPL-2.0-or-later

98KB
1.5K SLoC

An implementation of "Online Codes", a type of Fountain Code

This is just a placeholder package at the moment. It is intended to become a port/rework of my existing Perl/C implementations.

The existing Perl implementation is available as Net::OnlineCode on CPAN. The source is available on github under the Net-OnlineCode directory.

I note that there is another similarly-named package here on crates.io which implements the same algorithm. If you came here expecting to find that, you can find it here.

Version 0.1.1

This version implements a simple codec (encoder/decoder) that tests that all the code in the various modules works correctly.

Points of interest/note:

  • uses more natural idea of solving equations involving variables instead of implementing explicit bipartite graph

  • takes an RNG that implements RngCore rather than a fixed RNG (allows for easy customisation)

  • codec doesn't work with files (instead, one block = one u32), but that's easily extended

  • library only handles Online Code algorithm, so user is responsible for XORing file blocks (and networking)

  • use of HashSet turns out to be a big problem as far as performance is concerned; replacing it with even an unsorted list would probably improve things a lot. HashSet is also a source of non-determinism due to iterators returning set members in a random order.

  • is a faithful implementation of the original paper

  • core routines are well tested and I have a high degree of confidence that they're correct

Dependencies

~1MB
~20K SLoC