# small_ints [![GitHub Actions CI][ci-img]][ci]
[ci]: https://github.com/miniclip/small_ints
[ci-img]: https://github.com/miniclip/small_ints/workflows/build/badge.svg
`small_ints` is an Erlang module that can help you deal with encoding and
decoding of integers using the varint and ZigZag algorithms described in the
["Encoding" section][docs-protobuf] of Google Protocol Buffer's docs.
## Building
```bash
> rebar3 compile
```
### Varint
Basically, you use a variable number of bytes to represent a positive
integer. You can encode varints to binaries and decode them from binaries like
this:
```erlang
small_ints:encode_varint(5). %=> <<5>>
small_ints:encode_varint(1034). %=> <<138,8>>
small_ints:decode_varint(<<5,"foo">>). %=> {5, <<"foo">>}
small_ints:decode_varint(<<138,8>>). %=> {1034, <<>>}
```
### ZigZag
The ZigZag algorithm is used to encode small positive *and negative* numbers
with a small number of bytes.
```erlang
small_ints:encode_zigzag(1). %=> 2
small_ints:encode_zigzag(-5). %=> 9
small_ints:decode_zigzag(6). %=> 3
```
### Other stuff
`small_ints` also provides two utility functions which just combine the varint
and ZigZag algorithms:
* `small_ints:decode_zigzag_varint/1`: decodes the next varint from the given
binary and then decodes it with ZigZag
* `small_ints:encode_zigzag_varint/1`: encodes the given integer with ZigZag,
then encodes the result with varint
## License
MIT License © 2015, Andrea Leopardi
[docs-protobuf]: https://developers.google.com/protocol-buffers/docs/encoding
