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

2.8 KiB

crc Build Status

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

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

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.