projects / rustc.git / blame
| Commit | Line | Data |
|---|---|---|
| 0731742a XL |
1 | # crc32fast [![Build Status][travis-img]][travis] [![Crates.io][crates-img]][crates] [![Documentation][docs-img]][docs] |
| 2 | ||
| 3 | [travis-img]: https://travis-ci.com/srijs/rust-crc32fast.svg?branch=master | |
| 4 | [travis]: https://travis-ci.com/srijs/rust-crc32fast | |
| 5 | [crates-img]: https://img.shields.io/crates/v/crc32fast.svg | |
| 6 | [crates]: https://crates.io/crates/crc32fast | |
| 7 | [docs-img]: https://docs.rs/crc32fast/badge.svg | |
| 8 | [docs]: https://docs.rs/crc32fast | |
| 9 | ||
| 10 | _Fast, SIMD-accelerated CRC32 (IEEE) checksum computation_ | |
| 11 | ||
| 12 | ## Usage | |
| 13 | ||
| 14 | ```rust | |
| 15 | extern crate crc32fast; | |
| 16 | ||
| 17 | use crc32fast::Hasher; | |
| 18 | ||
| 19 | let mut hasher = Hasher::new(); | |
| 20 | hasher.update(b"foo bar baz"); | |
| 21 | let checksum = hasher.finalize(); | |
| 22 | ``` | |
| 23 | ||
| 24 | ## Performance | |
| 25 | ||
| 26 | This crate contains multiple CRC32 implementations: | |
| 27 | ||
| 28 | - A fast baseline implementation which processes up to 16 bytes per iteration | |
| 29 | - An optimized implementation for modern `x86` using `sse` and `pclmulqdq` instructions | |
| 30 | ||
| 31 | Calling the `Hasher::new` constructor at runtime will perform a feature detection to select the most | |
| 32 | optimal implementation for the current CPU feature set. | |
| 33 | ||
| 34 | | crate | version | variant | ns/iter | MB/s | | |
| 35 | |-------------------------------------|---------|-----------|---------|------| | |
| 36 | | [crc](https://crates.io/crates/crc) | 1.8.1 | n/a | 4,926 | 207 | | |
| 37 | | crc32fast (this crate) | 1.0.0 | baseline | 683 | 1499 | | |
| 38 | | crc32fast (this crate) | 1.0.0 | pclmulqdq | 140 | 7314 | | |
| 39 | ||
| 40 | ## Memory Safety | |
| 41 | ||
| 42 | Due to the use of SIMD intrinsics for the optimized implementations, this crate contains some amount of `unsafe` code. | |
| 43 | ||
| 44 | In order to ensure memory safety, the relevant code has been fuzz tested using [afl.rs](https://github.com/rust-fuzz/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. | |
| 45 | ||
| 46 | On top of that, every commit is tested using an address sanitizer in CI to catch any out of bounds memory accesses. | |
| 47 | ||
| 48 | 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. | |
| 49 | ||
| 50 | ## License | |
| 51 | ||
| 52 | This project is licensed under either of | |
| 53 | ||
| 54 | * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or | |
| 55 | http://www.apache.org/licenses/LICENSE-2.0) | |
| 56 | * MIT license ([LICENSE-MIT](LICENSE-MIT) or | |
| 57 | http://opensource.org/licenses/MIT) | |
| 58 | ||
| 59 | at your option. | |
| 60 | ||
| 61 | ### Contribution | |
| 62 | ||
| 63 | Unless you explicitly state otherwise, any contribution intentionally submitted | |
| 64 | for inclusion in this project by you, as defined in the Apache-2.0 license, | |
| 65 | shall be dual licensed as above, without any additional terms or conditions. |