Crate crc32 

Fast, SIMD-accelerated CRC32 (IEEE) checksum computation.

Usage

Simple usage

For simple use-cases, you can call the hash() convenience function to directly compute the CRC32 checksum for a given byte slice:

let checksum = crc32::hash(b"foo bar baz");

Advanced usage

For use-cases that require more flexibility or performance, for example when processing large amounts of data, you can create and manipulate a Hasher:

use crc32::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 using sse and pclmulqdq instructions
• An optimized implementation for aarch64 using the crc32 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.

Memory safety

Due to the use of SIMD intrinsics for the optimized implementations, this crate contains some amount of unsafe code. The baseline implementation is safe, and the specialized implementations are exercised by the crate’s tests, which are only compiled when the std feature is enabled.

Feature flags

std (default: enabled)

The crate can be 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.

Because runtime CPU feature detection requires OS support, the specialized SIMD implementations are unavailable when the std feature is disabled.

nightly (default: disabled)

Enables unstable features that are only available on the nightly channel. Enabling it makes the optimized aarch64 implementation available.

Structs

Hasher

Represents an in-progress CRC32 computation.

Functions

hash

Computes the CRC32 hash of a byte slice.