openethereum/util/plain_hasher/src/lib.rs
Niklas Adolfsson 98b7c07171 Update license header and scripts (#8666)
* Update `add_license` script

* run script

* add `remove duplicate lines script` and run it

* Revert changes `English spaces`

* strip whitespaces

* Revert `GPL` in files with `apache/mit license`

* don't append `gpl license` in files with other lic

* Don't append `gpl header` in files with other lic.

* re-ran script

* include c and cpp files too

* remove duplicate header

* rebase nit
2018-06-04 10:19:50 +02:00

76 lines
2.1 KiB
Rust

// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
#[macro_use]
extern crate crunchy;
extern crate ethereum_types;
use ethereum_types::H256;
use std::collections::{HashMap, HashSet};
use std::hash;
/// Specialized version of `HashMap` with H256 keys and fast hashing function.
pub type H256FastMap<T> = HashMap<H256, T, hash::BuildHasherDefault<PlainHasher>>;
/// Specialized version of `HashSet` with H256 keys and fast hashing function.
pub type H256FastSet = HashSet<H256, hash::BuildHasherDefault<PlainHasher>>;
/// Hasher that just takes 8 bytes of the provided value.
/// May only be used for keys which are 32 bytes.
#[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);
let mut bytes_ptr = bytes.as_ptr();
let mut prefix_ptr = &mut self.prefix as *mut u64 as *mut u8;
unroll! {
for _i in 0..8 {
unsafe {
*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 std::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);
}
}