https://github.com/tattdcodemonkey/crc
CRC library in elixir
https://github.com/tattdcodemonkey/crc
crc elixir nerves
Last synced: about 2 months ago
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CRC library in elixir
- Host: GitHub
- URL: https://github.com/tattdcodemonkey/crc
- Owner: TattdCodeMonkey
- License: mit
- Created: 2015-11-25T03:12:36.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2023-06-23T16:29:00.000Z (over 2 years ago)
- Last Synced: 2024-12-15T16:18:57.263Z (10 months ago)
- Topics: crc, elixir, nerves
- Language: C++
- Size: 379 KB
- Stars: 26
- Watchers: 3
- Forks: 14
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.md
Awesome Lists containing this project
README
# CRC
[](https://hex.pm/packages/crc)
[](https://hexdocs.pm/crc/)
[](https://hex.pm/packages/crc)
[](https://github.com/TattdCodeMonkey/crc/blob/master/LICENSE)
[](https://github.com/TattdCodeMonkey/crc/commits/master)
This module is used to calculate CRC (Cyclic Redundancy Check) values for binary data. It uses NIF functions written in C to iterate over the given binary calculating the CRC checksum value. The NIFs are written to report their time slice usage and will not interfere with the schedulers.
## Installation
### Elixir
Add `:crc` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:crc, "~> 0.10"}
]
end
```
### Erlang
Add `crc` to your `rebar.config`:
```erlang
{deps, [
{crc, "0.10.5"}
]}.
```
Or `erlang.mk`:
```erlang
dep_crc = hex 0.10.5
```
## Supported algorithms (models)
Run `CRC.list/0` to get a full list of all pre-defined models or `CRC.list/1` with a filter to search for a pre-defined model.
## Usage
To calculate a CRC-16 X-Modem checksum for the binary `<<1,2,3,4,5,4,3,2,1>>` using the pre-defined model:
```elixir
iex> CRC.crc(:crc_16_xmodem, <<1,2,3,4,5,4,3,2,1>>)
31763
iex> CRC.calculate(<<1,2,3,4,5,4,3,2,1>>, :crc_16_xmodem)
31763
```
Or you can create a model at runtime, this can be done with a map:
```elixir
iex> CRC.crc(
%{
width: 16,
poly: 0x1021,
init: 0x00,
refin: false,
refout: false,
xorout: 0x00
},
<<1,2,3,4,5,4,3,2,1>>
)
31763
iex> CRC.calculate(
<<1,2,3,4,5,4,3,2,1>>,
%{
width: 16,
poly: 0x1021,
init: 0x00,
refin: false,
refout: false,
xorout: 0x00
}
)
31763
```
Or you can extend one of the pre-defined models:
```elixir
iex> CRC.crc(
%{
extend: :crc_16_xmodem,
init: 0x00,
},
<<1,2,3,4,5,4,3,2,1>>
)
31763
```
`CRC.crc_init/1` is used to create a resource and be used to do partial updates to a calculation that is then finalized later:
```elixir
iex> resource = CRC.crc_init(:crc_16_xmodem)
#Reference
iex> resource2 = CRC.crc_update(resource, <<1, 2, 3, 4, 5>>)
#Reference
iex> resource3 = CRC.crc_update(resource2, <<4, 3, 2, 1>>)
#Reference
iex> CRC.crc_final(resource3)
31763
```
This could be useful to calculate a CRC for a larger binary that you are receiving asynchronously.
## Tests
CRC implementations have been tested against these online calculators to validate their correctness to the best of our ability.
- https://www.lammertbies.nl/comm/info/crc-calculation.html
- http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
There are also two property tests that can use [PyCRC](https://github.com/tpircher/pycrc) or [CRC RevEng](https://sourceforge.net/projects/reveng/) if installed and configured locally.
```bash
$ export PYCRC_BIN=~/pycrc-0.9.1/pycrc.py
$ export REVENG_BIN=~/reveng-1.5.2/reveng
$ mix test
```
PyCRC is used as a part of the TravisCI test suite.
## Copyright and License
Copyright (c) 2015 Rodney Norris
CRC is released under the MIT License. See the [LICENSE.md](./LICENSE.md) file
for further details.