Metadata-Version: 2.2
Name: anycrc
Version: 1.3.2
Summary: The fastest Python CRC Library
License: Zlib
Project-URL: Homepage, https://github.com/marzooqy/anycrc
Requires-Python: >=3.7
Description-Content-Type: text/markdown
License-File: LICENSE

This is a Cython module with bindings to the [crcany](https://github.com/madler/crcany) library. It supports calculating CRC hashes of arbitary sizes as well as updating a CRC hash over time.

## Installation

`pip install anycrc`

## Usage

Use an existing model:

```python
>>> import anycrc
>>> crc32 = anycrc.Model('CRC32-MPEG-2')
>>> crc32.calc(b'Hello World!')
2498069329
```

Create a CRC with specific parameters:

```python
>>> crc32 = anycrc.CRC(width=32, poly=0x04c11db7, init=0xffffffff, refin=False, refout=False, xorout=0x00000000)
>>> crc32.calc('Hello World!')
2498069329
```

Read the data in chunks:

```python
>>> value = crc32.calc(b'Hello ')
>>> crc32.calc(b'World!', value)
2498069329
```

The length of the data can be specified in bits by calling `calc_bits` and passing a [bitarray](https://github.com/ilanschnell/bitarray) object:

```python
>>> from bitarray import bitarray
>>> bits = bitarray()
>>> bits.frombytes(b'Hello World!')
>>> value = crc32.calc_bits(bits[:50])
>>> crc32.calc_bits(bits[50:], value)
2498069329
```

To use bit lengths with reflected CRCs, create a little endian bitarray object: `bitarray(endian='little')`

To combine two CRCs, provide the CRC values along with the length of the second CRC's message in bytes:

```python
>>> value = crc32.calc(b'Hello ')
>>> value2 = crc32.calc(b'World!')
>>> crc32.combine(value, value2, len(b'World!'))
2498069329
```

There is also a `combine_bits` method where the length argument is expected to be in bits.

For a list of pre-built models, check [models.py](https://github.com/marzooqy/anycrc/blob/main/src/anycrc/models.py). To get a list of the models at any time, use the following command:

`python -m anycrc models`

The maximum supported CRC width is 64 bits.

## Benchmark

| Module | Speed (MB/s) | Relative | Notes |
|---|:-:|:-:|:-:|
| pycrc32 | 22549.44 | x0.11 | CRC32 only |
| crc32c | 20990.32 | x0.12 | CRC32C only |
| google-crc32c | 17046.81 | x0.15 | CRC32C only |
| anycrc | 2591.08 | x1.00 ||
| zlib | 2028.04 | x1.28 | CRC32 only |
| fastcrc | 652.01 | x3.97 ||
| crcmod-plus | 647.36 | x4.00 ||
| crc-ct | 570.82 | x4.54 ||
| libscrc | 149.21 | x17.37 ||
| crcengine | 7.44 | x348.07 ||
| pycrc | 3.63 | x714.01 ||
| crccheck | 1.06 | x2449.24 ||
| crc | 0.34 | x7583.33 ||

Tested on a 10th generation Intel i7 processor.
