crc32fast

Fast CRC32 (IEEE) checksum computation

Usage

```rust extern crate crc32fast;

use crc32fast::Hasher;

let mut hasher = Hasher::new(); hasher.update(b"foo bar baz"); let checksum = hasher.finalize();

```

Performance

This crate contains multiple CRC32 implementations:

• A fast baseline implementation which processes up to 16 bytes per iteration
• An optimized implementation for modern x86 using sse and pclmulqdq instructions

Calling the Hasher::new constructor at runtime will perform a feature detection to select the most optimal implementation for the current CPU feature set.

| crate | version | variant | ns/iter | MB/s | |-------------------------------------|---------|-----------|---------|------| | crc | 1.8.1 | n/a | 4,926 | 207 | | crc32fast (this crate) | 1.0.0 | baseline | 683 | 1499 | | crc32fast (this crate) | 1.0.0 | pclmulqdq | 140 | 7314 |

Memory Safety

Due to the use of SIMD intrinsics for the optimized implementations, this crate contains some amount of unsafe code.

In order to ensure memory safety, the relevant code has been fuzz tested using afl.rs with millions of iterations in both debug and release build settings. You can inspect the test setup in the fuzz sub-directory, which also has instructions on how to run the tests yourself.

On top of that, every commit is tested using an address sanitizer in CI to catch any out of bounds memory accesses.

Even though neither fuzzing not sanitization has revealed any safety bugs yet, please don't hesitate to file an issue if you run into any crashes or other unexpected behaviour.