55 lines
1.5 KiB
JavaScript
55 lines
1.5 KiB
JavaScript
|
/**
|
||
|
|
* JS Implementation of MurmurHash2
|
||
|
|
*
|
||
|
|
* @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
|
||
|
|
* @see http://github.com/garycourt/murmurhash-js
|
||
|
|
* @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
|
||
|
|
* @see http://sites.google.com/site/murmurhash/
|
||
|
|
*
|
||
|
|
* @param {string} str ASCII only
|
||
|
|
* @param {number} seed Positive integer only
|
||
|
|
* @return {number} 32-bit positive integer hash
|
||
|
|
*/
|
||
|
|
|
||
|
|
function murmurhash2_32_gc(str, seed) {
|
||
|
|
var
|
||
|
|
l = str.length,
|
||
|
|
h = seed ^ l,
|
||
|
|
i = 0,
|
||
|
|
k;
|
||
|
|
|
||
|
|
while (l >= 4) {
|
||
|
|
k =
|
||
|
|
((str.charCodeAt(i) & 0xff)) |
|
||
|
|
((str.charCodeAt(++i) & 0xff) << 8) |
|
||
|
|
((str.charCodeAt(++i) & 0xff) << 16) |
|
||
|
|
((str.charCodeAt(++i) & 0xff) << 24);
|
||
|
|
|
||
|
|
k = (((k & 0xffff) * 0x5bd1e995) + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16));
|
||
|
|
k ^= k >>> 24;
|
||
|
|
k = (((k & 0xffff) * 0x5bd1e995) + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16));
|
||
|
|
|
||
|
|
h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16)) ^ k;
|
||
|
|
|
||
|
|
l -= 4;
|
||
|
|
++i;
|
||
|
|
}
|
||
|
|
|
||
|
|
switch (l) {
|
||
|
|
case 3: h ^= (str.charCodeAt(i + 2) & 0xff) << 16;
|
||
|
|
case 2: h ^= (str.charCodeAt(i + 1) & 0xff) << 8;
|
||
|
|
case 1: h ^= (str.charCodeAt(i) & 0xff);
|
||
|
|
h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16));
|
||
|
|
}
|
||
|
|
|
||
|
|
h ^= h >>> 13;
|
||
|
|
h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16));
|
||
|
|
h ^= h >>> 15;
|
||
|
|
|
||
|
|
return h >>> 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
if(typeof module !== undefined) {
|
||
|
|
module.exports = murmurhash2_32_gc
|
||
|
|
}
|