//! FNV-1a hashing for state checksums.
//!
//! The hash only has to reveal accidental divergence between peers. It is
//! not meant to resist tampering.

const FNV_OFFSET_BASIS: u64 = 0xcbf2_9ce4_8422_2325;
const FNV_PRIME: u64 = 0x0000_0100_0000_01b3;

/// Returns the 64-bit FNV-1a hash of `bytes`.
pub fn fnv1a64(bytes: &[u8]) -> u64 {
    let mut hash = FNV_OFFSET_BASIS;
    for &byte in bytes {
        hash ^= u64::from(byte);
        hash = hash.wrapping_mul(FNV_PRIME);
    }
    hash
}