31 lines
1.2 KiB
JavaScript
31 lines
1.2 KiB
JavaScript
|
// https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js
|
||
|
|
|
||
|
|
/*
|
||
|
|
cyrb53 (c) 2018 bryc (github.com/bryc)
|
||
|
|
License: Public domain. Attribution appreciated.
|
||
|
|
A fast and simple 53-bit string hash function with decent collision resistance.
|
||
|
|
Largely inspired by MurmurHash2/3, but with a focus on speed/simplicity.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
cyrb53a (c) 2023 bryc (github.com/bryc)
|
||
|
|
License: Public domain. Attribution appreciated.
|
||
|
|
The original cyrb53 has a slight mixing bias in the low bits of h1.
|
||
|
|
This shouldn't be a huge problem, but I want to try to improve it.
|
||
|
|
This new version should have improved avalanche behavior, but
|
||
|
|
it is not quite final, I may still find improvements.
|
||
|
|
So don't expect it to always produce the same output.
|
||
|
|
*/
|
||
|
|
export default function cyrb53a(str, seed = 0) {
|
||
|
|
let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
|
||
|
|
for(let i = 0, ch; i < str.length; i++) {
|
||
|
|
ch = str.charCodeAt(i);
|
||
|
|
h1 = Math.imul(h1 ^ ch, 0x85ebca77);
|
||
|
|
h2 = Math.imul(h2 ^ ch, 0xc2b2ae3d);
|
||
|
|
}
|
||
|
|
h1 ^= Math.imul(h1 ^ (h2 >>> 15), 0x735a2d97);
|
||
|
|
h2 ^= Math.imul(h2 ^ (h1 >>> 15), 0xcaf649a9);
|
||
|
|
h1 ^= h2 >>> 16; h2 ^= h1 >>> 16;
|
||
|
|
return 2097152 * (h2 >>> 0) + (h1 >>> 11);
|
||
|
|
};
|