use core::num::Wrapping;
pub fn digest(mut data: &[u8]) -> u32 {
let len: u32 = data.len() as u32;
let mut hash: Wrapping<u32> = Wrapping(len);
if len == 0 {
return 0;
}
for _i in 0..(len >> 2) {
hash += Wrapping(u16::from_le_bytes([data[0], data[1]]) as u32);
let temp = Wrapping(u16::from_le_bytes([data[2], data[3]]) as u32) << 11 ^ hash;
hash = hash << 16 ^ temp;
data = &data[4..];
hash += hash >> 11;
}
match len & 3 {
0 => {
}
1 => {
hash += Wrapping(data[0] as u32);
hash ^= hash << 10;
hash += hash >> 1;
}
2 => {
hash += Wrapping(u16::from_le_bytes([data[0], data[1]]) as u32);
hash ^= hash << 11;
hash += hash >> 17;
}
3 => {
hash += Wrapping(u16::from_le_bytes([data[0], data[1]]) as u32);
hash ^= hash << 16;
hash ^= Wrapping(data[2] as u32) << 18;
hash += hash >> 11;
}
_ => unreachable!(),
}
hash ^= hash << 3;
hash += hash >> 5;
hash ^= hash << 4;
hash += hash >> 17;
hash ^= hash << 25;
hash += hash >> 6;
hash.0
}
#[cfg(test)]
mod hiesh_tests {
use super::digest;
#[test]
fn test_digest() {
assert_eq!(digest(b"Hello World!"), 1774740540);
assert_eq!(digest(b"Hsieh Hash"), 1552477933);
assert_eq!(digest(b"SuperFastHash"), 2245601745);
assert_eq!(digest(b"pirateDay"), 2774317235);
}
}