You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
138 lines
4.3 KiB
138 lines
4.3 KiB
/**
|
|
* @preserve
|
|
* JS Implementation of incremental MurmurHash3 (r150) (as of May 10, 2013)
|
|
*
|
|
* @author <a href="mailto:jensyt@gmail.com">Jens Taylor</a>
|
|
* @see http://github.com/homebrewing/brauhaus-diff
|
|
* @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/
|
|
*/
|
|
(function(){
|
|
var cache;
|
|
|
|
// Call this function without `new` to use the cached object (good for
|
|
// single-threaded environments), or with `new` to create a new object.
|
|
//
|
|
// @param {string} key A UTF-16 or ASCII string
|
|
// @param {number} seed An optional positive integer
|
|
// @return {object} A MurmurHash3 object for incremental hashing
|
|
function MurmurHash3(key, seed) {
|
|
var m = this instanceof MurmurHash3 ? this : cache;
|
|
m.reset(seed)
|
|
if (typeof key === 'string' && key.length > 0) {
|
|
m.hash(key);
|
|
}
|
|
|
|
if (m !== this) {
|
|
return m;
|
|
}
|
|
};
|
|
|
|
// Incrementally add a string to this hash
|
|
//
|
|
// @param {string} key A UTF-16 or ASCII string
|
|
// @return {object} this
|
|
MurmurHash3.prototype.hash = function(key) {
|
|
var h1, k1, i, top, len;
|
|
|
|
len = key.length;
|
|
this.len += len;
|
|
|
|
k1 = this.k1;
|
|
i = 0;
|
|
switch (this.rem) {
|
|
case 0: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) : 0;
|
|
case 1: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 8 : 0;
|
|
case 2: k1 ^= len > i ? (key.charCodeAt(i++) & 0xffff) << 16 : 0;
|
|
case 3:
|
|
k1 ^= len > i ? (key.charCodeAt(i) & 0xff) << 24 : 0;
|
|
k1 ^= len > i ? (key.charCodeAt(i++) & 0xff00) >> 8 : 0;
|
|
}
|
|
|
|
this.rem = (len + this.rem) & 3; // & 3 is same as % 4
|
|
len -= this.rem;
|
|
if (len > 0) {
|
|
h1 = this.h1;
|
|
while (1) {
|
|
k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;
|
|
k1 = (k1 << 15) | (k1 >>> 17);
|
|
k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;
|
|
|
|
h1 ^= k1;
|
|
h1 = (h1 << 13) | (h1 >>> 19);
|
|
h1 = (h1 * 5 + 0xe6546b64) & 0xffffffff;
|
|
|
|
if (i >= len) {
|
|
break;
|
|
}
|
|
|
|
k1 = ((key.charCodeAt(i++) & 0xffff)) ^
|
|
((key.charCodeAt(i++) & 0xffff) << 8) ^
|
|
((key.charCodeAt(i++) & 0xffff) << 16);
|
|
top = key.charCodeAt(i++);
|
|
k1 ^= ((top & 0xff) << 24) ^
|
|
((top & 0xff00) >> 8);
|
|
}
|
|
|
|
k1 = 0;
|
|
switch (this.rem) {
|
|
case 3: k1 ^= (key.charCodeAt(i + 2) & 0xffff) << 16;
|
|
case 2: k1 ^= (key.charCodeAt(i + 1) & 0xffff) << 8;
|
|
case 1: k1 ^= (key.charCodeAt(i) & 0xffff);
|
|
}
|
|
|
|
this.h1 = h1;
|
|
}
|
|
|
|
this.k1 = k1;
|
|
return this;
|
|
};
|
|
|
|
// Get the result of this hash
|
|
//
|
|
// @return {number} The 32-bit hash
|
|
MurmurHash3.prototype.result = function() {
|
|
var k1, h1;
|
|
|
|
k1 = this.k1;
|
|
h1 = this.h1;
|
|
|
|
if (k1 > 0) {
|
|
k1 = (k1 * 0x2d51 + (k1 & 0xffff) * 0xcc9e0000) & 0xffffffff;
|
|
k1 = (k1 << 15) | (k1 >>> 17);
|
|
k1 = (k1 * 0x3593 + (k1 & 0xffff) * 0x1b870000) & 0xffffffff;
|
|
h1 ^= k1;
|
|
}
|
|
|
|
h1 ^= this.len;
|
|
|
|
h1 ^= h1 >>> 16;
|
|
h1 = (h1 * 0xca6b + (h1 & 0xffff) * 0x85eb0000) & 0xffffffff;
|
|
h1 ^= h1 >>> 13;
|
|
h1 = (h1 * 0xae35 + (h1 & 0xffff) * 0xc2b20000) & 0xffffffff;
|
|
h1 ^= h1 >>> 16;
|
|
|
|
return h1 >>> 0;
|
|
};
|
|
|
|
// Reset the hash object for reuse
|
|
//
|
|
// @param {number} seed An optional positive integer
|
|
MurmurHash3.prototype.reset = function(seed) {
|
|
this.h1 = typeof seed === 'number' ? seed : 0;
|
|
this.rem = this.k1 = this.len = 0;
|
|
return this;
|
|
};
|
|
|
|
// A cached object to use. This can be safely used if you're in a single-
|
|
// threaded environment, otherwise you need to create new hashes to use.
|
|
cache = new MurmurHash3();
|
|
|
|
if (typeof(module) != 'undefined') {
|
|
module.exports = MurmurHash3;
|
|
} else {
|
|
this.MurmurHash3 = MurmurHash3;
|
|
}
|
|
}());
|
|
|