Crate fletcher_simd

fletcher-simd

A SIMD implementation of the Fletcher’s checksum algorithm.

Note: This implementation uses a modulus of 2^k where k is the checksum block size in bits, as this is fast with wrapping math. Other implementations may use 2^k - 1.

Features

• Uses std::simd, which currently requires nightly.
• Supports all architectures supported by std::simd.
• Both run-time and compile-time detection available via the multiversion crate.
• Scalar fallback.

Cargo features

There is one cargo feature, runtime_dispatch, enabled by default. When enabled, the crate will use CPU feature detection at runtime to dispatch to the appropriate SIMD implementation. Disabling this feature will result in static dispatch only.

Example

use byteorder::{ByteOrder, LittleEndian};
use fletcher_simd::Fletcher128;

fn main() {
    const DATA: &str = "abcdefgh";
    let mut fletcher = Fletcher128::new();

    // Read bytes in little endian. Endianness matters!
    fletcher.update_with_iter(
        DATA.as_bytes()
            .chunks(8)
            .map(|chunk| LittleEndian::read_u64(chunk)),
    );

    assert_eq!(fletcher.value(), 0x68676665646362616867666564636261);
}

Structs

Fletcher

A Fletcher checksum object that allows for continuous updates to the checksum.

Traits

FletcherChecksum

Trait for the type representing a certain sized Fletcher checksum.

Type Definitions

Fletcher16

Convenient type alias for the 16-bit Fletcher checksum object.

Fletcher32

Convenient type alias for the 32-bit Fletcher checksum object.

Fletcher64

Convenient type alias for the 64-bit Fletcher checksum object.

Fletcher128

Convenient type alias for the 128-bit Fletcher checksum object.