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benches | ||
src | ||
.cargo-checksum.json | ||
Cargo.toml | ||
LICENSE-APACHE | ||
LICENSE-MIT | ||
README.md | ||
build.rs |
README.md
crc32fast
Fast, SIMD-accelerated CRC32 (IEEE) checksum computation
Usage
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
usingsse
andpclmulqdq
instructions - An optimized implementation for
aarch64
usingcrc32
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.
Available feature flags
std
(default: enabled)
This library supports being built without the Rust std
library, which is useful for low-level use-cases such as embedded where no operating system is available. To build the crate in a no_std
context, disable the default std
feature.
Note: Because runtime CPU feature detection requires OS support, the specialized SIMD implementations will be unavailable when the std
feature is disabled.
nightly
(default: disabled)
This feature flag enables unstable features that are only available on the nightly
channel. Keep in mind that when enabling this feature flag, you
might experience breaking changes when updating compiler versions.
Currently, enabling this feature flag will make the optimized aarch64
implementation available.
License
This project is licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.