src/thirdparty/murmurhash3_gc.js - master - githubmirror/brackets

src/thirdparty/murmurhash3_gc.js
124 строки3 KB
Kevin Dangoor
adds weight and signatures to the DOM (signature is MurmurHash3)
20 июн 2013, 06:50
20 июн 2013, 06:50b7cee16
/* Public Domain MurmurHash3 implementation. Altered to have AMD header and function wrapper. */

define(function (require, exports, module) {

/*
 *  The MurmurHash3 algorithm was created by Austin Appleby.  This JavaScript port was authored
 *  by Peter Zotov (based on Java port by Yonik Seeley) and is placed into the public domain.
 *  The author hereby disclaims copyright to this source code.
 *
 *  This produces exactly the same hash values as the final C++ version of MurmurHash3 and
 *  is thus suitable for producing the same hash values across platforms.
 *
 *  There are two versions of this hash implementation. First interprets the string as a
 *  sequence of bytes, ignoring most significant byte of each codepoint. The second one
 *  interprets the string as a UTF-16 codepoint sequence, and appends each 16-bit codepoint
 *  to the hash independently. The latter mode was not written to be compatible with
 *  any other implementation, but it should offer better performance for JavaScript-only
 *  applications.
 *
 *  See http://github.com/whitequark/murmurhash3-js for future updates to this file.
 */

var MurmurHash3 = {
	mul32: function(m, n) {
		var nlo = n & 0xffff;
		var nhi = n - nlo;
		return ((nhi * m | 0) + (nlo * m | 0)) | 0;
	},

	hashBytes: function(data, len, seed) {
		var c1 = 0xcc9e2d51, c2 = 0x1b873593;

		var h1 = seed;
		var roundedEnd = len & ~0x3;

		for (var i = 0; i < roundedEnd; i += 4) {
			var k1 = (data.charCodeAt(i)     & 0xff)        |
				((data.charCodeAt(i + 1) & 0xff) << 8)  |
				((data.charCodeAt(i + 2) & 0xff) << 16) |
				((data.charCodeAt(i + 3) & 0xff) << 24);

			k1 = this.mul32(k1, c1);
			k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17);  // ROTL32(k1,15);
			k1 = this.mul32(k1, c2);

			h1 ^= k1;
			h1 = ((h1 & 0x7ffff) << 13) | (h1 >>> 19);  // ROTL32(h1,13);
			h1 = (h1 * 5 + 0xe6546b64) | 0;
		}

		k1 = 0;

		switch(len % 4) {
			case 3:
				k1 = (data.charCodeAt(roundedEnd + 2) & 0xff) << 16;
				// fallthrough
			case 2:
				k1 |= (data.charCodeAt(roundedEnd + 1) & 0xff) << 8;
				// fallthrough
			case 1:
				k1 |= (data.charCodeAt(roundedEnd) & 0xff);
				k1 = this.mul32(k1, c1);
				k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17);  // ROTL32(k1,15);
				k1 = this.mul32(k1, c2);
				h1 ^= k1;
		}

		// finalization
		h1 ^= len;

		// fmix(h1);
		h1 ^= h1 >>> 16;
		h1  = this.mul32(h1, 0x85ebca6b);
		h1 ^= h1 >>> 13;
		h1  = this.mul32(h1, 0xc2b2ae35);
		h1 ^= h1 >>> 16;

		return h1;
	},

	hashString: function(data, len, seed) {
		var c1 = 0xcc9e2d51, c2 = 0x1b873593;

		var h1 = seed;
		var roundedEnd = len & ~0x1;

		for (var i = 0; i < roundedEnd; i += 2) {
			var k1 = data.charCodeAt(i) | (data.charCodeAt(i + 1) << 16);

			k1 = this.mul32(k1, c1);
			k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17);  // ROTL32(k1,15);
			k1 = this.mul32(k1, c2);

			h1 ^= k1;
			h1 = ((h1 & 0x7ffff) << 13) | (h1 >>> 19);  // ROTL32(h1,13);
			h1 = (h1 * 5 + 0xe6546b64) | 0;
		}

		if((len % 2) == 1) {
			k1 = data.charCodeAt(roundedEnd);
			k1 = this.mul32(k1, c1);
			k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17);  // ROTL32(k1,15);
			k1 = this.mul32(k1, c2);
			h1 ^= k1;
		}

		// finalization
		h1 ^= (len << 1);

		// fmix(h1);
		h1 ^= h1 >>> 16;
		h1  = this.mul32(h1, 0x85ebca6b);
		h1 ^= h1 >>> 13;
		h1  = this.mul32(h1, 0xc2b2ae35);
		h1 ^= h1 >>> 16;

		return h1;
	}
};

if(typeof module !== "undefined" && typeof module.exports !== "undefined") {
	module.exports = MurmurHash3;
}
});