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#![no_std]
#[macro_use]
extern crate crunchy;
use core::{hash, mem};
#[derive(Default)]
pub struct PlainHasher {
prefix: u64,
}
impl hash::Hasher for PlainHasher {
#[inline]
fn finish(&self) -> u64 {
self.prefix
}
#[inline]
#[allow(unused_assignments)]
fn write(&mut self, bytes: &[u8]) {
debug_assert!(bytes.len() == 32);
unsafe {
let mut bytes_ptr = bytes.as_ptr();
let prefix_u8: &mut [u8; 8] = mem::transmute(&mut self.prefix);
let mut prefix_ptr = prefix_u8.as_mut_ptr();
unroll! {
for _i in 0..8 {
*prefix_ptr ^= (*bytes_ptr ^ *bytes_ptr.offset(8)) ^ (*bytes_ptr.offset(16) ^ *bytes_ptr.offset(24));
bytes_ptr = bytes_ptr.offset(1);
prefix_ptr = prefix_ptr.offset(1);
}
}
}
}
}
#[cfg(test)]
mod tests {
use core::hash::Hasher;
use super::PlainHasher;
#[test]
fn it_works() {
let mut bytes = [32u8; 32];
bytes[0] = 15;
let mut hasher = PlainHasher::default();
hasher.write(&bytes);
assert_eq!(hasher.prefix, 47);
}
}