68 lines
2.0 KiB
JavaScript
68 lines
2.0 KiB
JavaScript
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namespace("Hash");
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/**
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* JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)
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*
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* @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
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* @see http://github.com/garycourt/murmurhash-js
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* @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
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* @see http://sites.google.com/site/murmurhash/
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*
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* @param {string} key ASCII only
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* @param {number} seed Positive integer only
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* @return {number} 32-bit positive integer hash
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*/
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Hash.Murmur3 = function(key, seed)
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{
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var remainder, bytes, h1, h1b, c1, c1b, c2, c2b, k1, i;
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remainder = key.length & 3; // key.length % 4
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bytes = key.length - remainder;
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h1 = seed;
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c1 = 0xcc9e2d51;
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c2 = 0x1b873593;
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i = 0;
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while (i < bytes) {
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k1 =
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((key.charCodeAt(i) & 0xff)) |
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((key.charCodeAt(++i) & 0xff) << 8) |
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((key.charCodeAt(++i) & 0xff) << 16) |
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((key.charCodeAt(++i) & 0xff) << 24);
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++i;
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k1 = ((((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16))) & 0xffffffff;
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k1 = (k1 << 15) | (k1 >>> 17);
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k1 = ((((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16))) & 0xffffffff;
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h1 ^= k1;
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h1 = (h1 << 13) | (h1 >>> 19);
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h1b = ((((h1 & 0xffff) * 5) + ((((h1 >>> 16) * 5) & 0xffff) << 16))) & 0xffffffff;
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h1 = (((h1b & 0xffff) + 0x6b64) + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16));
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}
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k1 = 0;
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switch (remainder) {
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case 3: k1 ^= (key.charCodeAt(i + 2) & 0xff) << 16;
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case 2: k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;
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case 1: k1 ^= (key.charCodeAt(i) & 0xff);
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k1 = (((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;
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k1 = (k1 << 15) | (k1 >>> 17);
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k1 = (((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;
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h1 ^= k1;
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}
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h1 ^= key.length;
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h1 ^= h1 >>> 16;
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h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) & 0xffffffff;
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h1 ^= h1 >>> 13;
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h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16))) & 0xffffffff;
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h1 ^= h1 >>> 16;
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return h1 >>> 0;
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} |