sthash 0.2.16

A very fast cryptographic hash function for large data.
Documentation 
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use super::*;

impl Hasher<'_> {
    #[cfg(target_arch = "x86_64")]
    #[target_feature(enable = "avx2")]
    pub(crate) unsafe fn hash_avx2(&self, out: &mut [u8; 16], msg: &[u8]) {
        let key = self.key;
        let mut poly_key = [0u8; 16];
        poly_key.copy_from_slice(&key[0..16]);
        let nh_key = &key[16..];
        let mut nh_out = vec![];
        let mut remaining = msg.len();
        let mut off = 0;
        let mut st_poly = poly1305::Hasher::new(poly_key);
        let st_nh = nh::Hasher::new(nh_key);
        while remaining > nh::NH_MESSAGE_BYTES {
            st_nh.hash_avx2(&mut nh_out, &msg[off..off + nh::NH_MESSAGE_BYTES]);
            if nh_out.len() == nh::NH_OUTPUT_BYTES * NHPOLY_HASHES_PER_POLY {
                st_poly.update(&nh_out);
                nh_out.truncate(0);
            }
            off += nh::NH_MESSAGE_BYTES;
            remaining -= nh::NH_MESSAGE_BYTES;
        }
        if remaining > 0 {
            let mask = nh::NH_MESSAGE_UNIT - 1;
            let padded_len = (remaining + mask) & !mask;
            let mut unit = [0u8; nh::NH_MESSAGE_BYTES];
            let padded = &mut unit[..padded_len];
            padded[..remaining].copy_from_slice(&msg[off..]);
            st_nh.hash(&mut nh_out, &padded);
        }
        if !nh_out.is_empty() {
            st_poly.update(&nh_out);
        }
        st_poly.finalize_noadd(out);
    }
}