Fast COBS encoder and decoder

This repository is a fast implementation of Consistent Overhead Byte Stuffing (COBS). It doesn't do much, but it does it fast. Although there might be eventual fixups and feature expansions for streaming codecs, assume the library is "done".

Performance

You can run the benchmarks to see the performance of the safe versions, unsafe versions and the currently most popular Rust cobs package (v0.5.0).

% cargo bench -- --quiet

The report was post-processed to make it denser, but you will see something along the lines of:

Benchmark Environment:
  OS:        Darwin 26.1
  Kernel:    25.1.0
  Arch:      aarch64
  CPU:       Apple M2 Max
  Cores:     12
  Memory:    35.85 GB / 64.00 GB
  Build:     release
  Rustc:     rustc 1.91.1 (ed61e7d7e 2025-11-07)

encode/16                   10.035 ns    1.4849 GiB/s
encode/256                  152.35 ns    1.5649 GiB/s
encode/4096                 2.5176 µs    1.5152 GiB/s
encode/65536                40.048 µs    1.5240 GiB/s
encode/262144               161.20 µs    1.5145 GiB/s
encode/1048576              646.75 µs    1.5100 GiB/s
encode/4194304              2.6169 ms    1.4927 GiB/s

decode/16                   6.6440 ns    2.2428 GiB/s
decode/256                  93.850 ns    2.5404 GiB/s
decode/4096                 1.6847 µs    2.2644 GiB/s
decode/65536                25.811 µs    2.3647 GiB/s
decode/262144               103.24 µs    2.3649 GiB/s
decode/1048576              410.68 µs    2.3779 GiB/s
decode/4194304              1.6388 ms    2.3836 GiB/s

encode_unsafe/16            10.030 ns    1.4856 GiB/s
encode_unsafe/256           151.94 ns    1.5692 GiB/s
encode_unsafe/4096          2.4241 µs    1.5736 GiB/s
encode_unsafe/65536         39.285 µs    1.5536 GiB/s
encode_unsafe/262144        160.81 µs    1.5182 GiB/s
encode_unsafe/1048576       633.76 µs    1.5409 GiB/s
encode_unsafe/4194304       2.5506 ms    1.5315 GiB/s

decode_unsafe/16            6.5473 ns    2.2759 GiB/s
decode_unsafe/256           92.253 ns    2.5844 GiB/s
decode_unsafe/4096          1.5776 µs    2.4181 GiB/s
decode_unsafe/65536         25.099 µs    2.4318 GiB/s
decode_unsafe/262144        100.89 µs    2.4200 GiB/s
decode_unsafe/1048576       403.07 µs    2.4228 GiB/s
decode_unsafe/4194304       1.6262 ms    2.4021 GiB/s

jamesmunns/encode/16        10.572 ns    1.4095 GiB/s
jamesmunns/encode/256       155.71 ns    1.5312 GiB/s
jamesmunns/encode/4096      2.6554 µs    1.4366 GiB/s
jamesmunns/encode/65536     43.878 µs    1.3910 GiB/s
jamesmunns/encode/262144    164.73 µs    1.4821 GiB/s
jamesmunns/encode/1048576   670.64 µs    1.4562 GiB/s
jamesmunns/encode/4194304   2.6897 ms    1.4523 GiB/s

jamesmunns/decode/16        18.433 ns    827.79 MiB/s
jamesmunns/decode/256       269.78 ns    904.95 MiB/s
jamesmunns/decode/4096      4.3558 µs    896.80 MiB/s
jamesmunns/decode/65536     69.413 µs    900.41 MiB/s
jamesmunns/decode/262144    280.18 µs    892.28 MiB/s
jamesmunns/decode/1048576   1.1186 ms    893.97 MiB/s
jamesmunns/decode/4194304   4.5029 ms    888.32 MiB/s