datacard-rs 1.0.0

Generic binary card format library with checksums and pluggable format traits
Documentation 
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//! CRC32 checksum utilities for DataCard

use crc32fast::Hasher;

/// Calculate CRC32 checksum over multiple byte slices
pub fn calculate_crc32(parts: &[&[u8]]) -> u32 {
    let mut hasher = Hasher::new();
    for part in parts {
        hasher.update(part);
    }
    hasher.finalize()
}

/// Calculate CRC32 checksum for a single byte slice
pub fn calculate_crc32_single(data: &[u8]) -> u32 {
    let mut hasher = Hasher::new();
    hasher.update(data);
    hasher.finalize()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_crc32_empty() {
        let checksum = calculate_crc32(&[]);
        assert_eq!(checksum, 0);
    }

    #[test]
    fn test_crc32_single() {
        let data = b"Hello, World!";
        let checksum = calculate_crc32_single(data);
        assert_ne!(checksum, 0);
    }

    #[test]
    fn test_crc32_multiple_parts() {
        let part1 = b"Hello, ";
        let part2 = b"World!";

        let checksum_combined = calculate_crc32(&[part1, part2]);
        let checksum_single = calculate_crc32_single(b"Hello, World!");

        assert_eq!(checksum_combined, checksum_single);
    }

    #[test]
    fn test_crc32_deterministic() {
        let data = b"test data";
        let checksum1 = calculate_crc32_single(data);
        let checksum2 = calculate_crc32_single(data);
        assert_eq!(checksum1, checksum2);
    }
}