gecko-dev/third_party/rust/crc/README.md

crc

Rust implementation of CRC(32, 64) with support of various standards

• Crate
• Documentation
• Usage
• Benchmark
• License

Usage

Add crc to Cargo.toml

[dependencies]
crc = "^1.0.0"

or

[dependencies.crc]
git = "https://github.com/mrhooray/crc-rs"

Add this to crate root

extern crate crc;

Compute CRC32

use crc::{crc32, Hasher32};

// CRC-32-IEEE being the most commonly used one
assert_eq!(crc32::checksum_ieee(b"123456789"), 0xcbf43926);
assert_eq!(crc32::checksum_castagnoli(b"123456789"), 0xe3069283);
assert_eq!(crc32::checksum_koopman(b"123456789"), 0x2d3dd0ae);

// use provided or custom polynomial
let mut digest = crc32::Digest::new(crc32::IEEE);
digest.write(b"123456789");
assert_eq!(digest.sum32(), 0xcbf43926);

// with initial
let mut digest = crc32::Digest::new_with_initial(crc32::IEEE, 0u32);
digest.write(b"123456789");
assert_eq!(digest.sum32(), 0xcbf43926);

Compute CRC64

use crc::{crc64, Hasher64};

assert_eq!(crc64::checksum_ecma(b"123456789"), 0x995dc9bbdf1939fa);
assert_eq!(crc64::checksum_iso(b"123456789"), 0xb90956c775a41001);

// use provided or custom polynomial
let mut digest = crc64::Digest::new(crc64::ECMA);
digest.write(b"123456789");
assert_eq!(digest.sum64(), 0x995dc9bbdf1939fa);

// with initial
let mut digest = crc64::Digest::new_with_initial(crc64::ECMA, 0u64);
digest.write(b"123456789");
assert_eq!(digest.sum64(), 0x995dc9bbdf1939fa);

Benchmark

Bencher is currently not available in Rust stable releases.

cargo bench with 2.3 GHz Intel Core i7 results ~430MB/s throughput. Comparison

cargo bench
     Running target/release/bench-5c82e94dab3e9c79

running 4 tests
test bench_crc32_make_table       ... bench:       439 ns/iter (+/- 82)
test bench_crc32_update_megabytes ... bench:   2327803 ns/iter (+/- 138845)
test bench_crc64_make_table       ... bench:      1200 ns/iter (+/- 223)
test bench_crc64_update_megabytes ... bench:   2322472 ns/iter (+/- 92870)

test result: ok. 0 passed; 0 failed; 0 ignored; 4 measured

License

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 the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.