https://github.com/code-inflation/pycrc32
SIMD-accelerated CRC32 checksum computation
https://github.com/code-inflation/pycrc32
checksum crc crc32 pycrc python python-crc rust simd
Last synced: 2 months ago
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SIMD-accelerated CRC32 checksum computation
- Host: GitHub
- URL: https://github.com/code-inflation/pycrc32
- Owner: code-inflation
- License: mit
- Created: 2024-02-10T15:33:56.000Z (almost 2 years ago)
- Default Branch: master
- Last Pushed: 2025-09-08T12:26:50.000Z (4 months ago)
- Last Synced: 2025-09-25T14:40:34.214Z (4 months ago)
- Topics: checksum, crc, crc32, pycrc, python, python-crc, rust, simd
- Language: Python
- Homepage:
- Size: 63.5 KB
- Stars: 3
- Watchers: 2
- Forks: 0
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# pycrc32
`pycrc32` is a Python module for SIMD-accelerated CRC32 checksum computation.
Big thanks to [rust-crc32fast](https://github.com/srijs/rust-crc32fast) - this project just provides Python bindings for their Rust implementation.
## Installation
```sh
pip install pycrc32
```
## Usage
```python
from pycrc32 import crc32
data = b"123456789"
print(f"crc32 for {data!r} is {crc32(data)}")
```
### Advanced Checksum Calculation with `Hasher`
For scenarios that require more flexibility, such as processing large amounts of data or computing the checksum in stages, you can use the `Hasher` class:
```python
from pycrc32 import Hasher
# Create a new Hasher instance
hasher = Hasher()
# Update the hasher with data chunks
hasher.update(b"123456")
hasher.update(b"789")
# Finalize the computation and get the checksum
checksum = hasher.finalize()
print(f"Checksum: {checksum}")
# Reset the hasher to compute another checksum
hasher.reset()
hasher.update(b"The quick brown fox jumps over the lazy dog")
new_checksum = hasher.finalize()
print(f"New checksum: {new_checksum}")
```
You can also initialize a `Hasher` with a specific initial CRC32 state:
```python
initial_crc = 12345678
hasher = Hasher.with_initial(initial_crc)
hasher.update(b"additional data")
final_checksum = hasher.finalize()
print(f"Final checksum with initial state: {final_checksum}")
```
To combine checksums from different data blocks without needing to concatenate the data, use the `combine` method:
```python
hasher1 = Hasher()
hasher1.update(b"Data block 1")
checksum1 = hasher1.finalize()
hasher2 = Hasher()
hasher2.update(b"Data block 2")
checksum2 = hasher2.finalize()
# Combine checksums from hasher1 into hasher2
hasher1.combine(hasher2) # Combine the state of hasher2 into hasher1
# The final checksum after combination
combined_checksum = hasher1.finalize()
print(f"Combined checksum: {combined_checksum}")
```
## Speed
The performance of `pycrc32` has been benchmarked on a trusty old Intel i7-8550U using 32MB of random input data. Below is a comparison of the median computation times across different libraries:
| Library | Median Time (s) |
|-----------|-----------------|
| `pycrc32` | 0.002703 |
| `zlib` | 0.019796 |
| `fastcrc` | 0.071426 |
We reach almost 10x performance improvements compared to the `zlib` baseline implementation.
See `scripts/bench.py` for more details.