Crate crc8_rs

A no_std library for doing 8-bit cyclic redundancy checks. This is mostly meant for embedded hardware, but it can be used in a std environment as well. This uses const generics from Rust 15.1 which is available in stable from Match 25th, 2021, before then you will have to use the Rust beta.

Usage

Inserting and verifying corrupting byte arrays.

use crc8::{ verify_crc8, insert_crc8 };

const GENERATOR_POLYNOMIAL: u8 = 0xD5;

// We add an empty byte at the end for the CRC
let msg = b"Hello World!\0";
let msg = insert_crc8(&msg, GENERATOR_POLYNOMIAL);

// Will verify just fine!
assert!(verify_crc8(&msg, GENERATOR_POLYNOMIAL));

let corrupted_msg = {
    let mut tmp_msg = msg;
    tmp_msg[1] = b'a';
    tmp_msg
};

// The message is now corrupted and thus it can't verify the integrity!
assert!(!verify_crc8(&corrupted_msg, GENERATOR_POLYNOMIAL));

Adding a CRC to custom Packet struct

use crc8::{ fetch_crc8, verify_crc8, concat_byte_arrays };

const GENERATOR_POLYNOMIAL: u8 = 0xD5;

// We can declare our packets ourselves
struct Packet {
    header: u8,
    content: [u8; 14],
    crc: u8,
}

impl Packet {
    fn new(header: u8, content: [u8; 14]) -> Packet {
        let mut pkt = Packet {
            header,
            content,
            crc: 0,
        };

        pkt.crc = GENERATOR_POLYNOMIAL ^ fetch_crc8(
            &pkt.to_bytes(),
            GENERATOR_POLYNOMIAL
        );
        pkt
    }

    fn to_bytes(&self) -> [u8; 16] {
        concat_byte_arrays::<16, 15, 1>(
            concat_byte_arrays::<15, 1, 14>([self.header], self.content),
            [self.crc]
        )
    }
}

assert!(verify_crc8(
    &Packet::new(b'H', *b"ello everyone!").to_bytes(),
    GENERATOR_POLYNOMIAL)
);

License

Licensed under a MIT license.

Functions

concat_byte_arrays	Concatenate two byte arrays into one byte array with compile time validation.
fetch_crc8	Generate Cyclic Redundancy Check for a given bytes array given a certain generator polynomial.
insert_crc8	Insert CRC on the last byte of a bytes array so that it can be verified.
verify_crc8	Verify the integrity of the bytes array.