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| /** | |
| * @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; | |
| } | |
| }()); | |