113 lines
1.9 KiB
JavaScript
113 lines
1.9 KiB
JavaScript
/*!
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* murmur3.js - murmur3 hash for bcoin
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* Copyright (c) 2014-2015, Fedor Indutny (MIT License)
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* Copyright (c) 2014-2016, Christopher Jeffrey (MIT License).
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* https://github.com/bcoin-org/bcoin
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*/
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'use strict';
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var native = require('./native').binding;
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/**
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* Murmur3 hash.
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* @memberof Bloom
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* @param {Buffer} data
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* @param {Number} seed
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* @returns {Number}
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*/
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function murmur3(data, seed) {
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var tail = data.length - (data.length % 4);
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var c1 = 0xcc9e2d51;
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var c2 = 0x1b873593;
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var h1 = seed;
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var i, k1;
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for (i = 0; i < tail; i += 4) {
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k1 = (data[i + 3] << 24)
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| (data[i + 2] << 16)
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| (data[i + 1] << 8)
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| data[i];
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k1 = mul32(k1, c1);
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k1 = rotl32(k1, 15);
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k1 = mul32(k1, c2);
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h1 ^= k1;
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h1 = rotl32(h1, 13);
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h1 = sum32(mul32(h1, 5), 0xe6546b64);
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}
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k1 = 0;
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switch (data.length & 3) {
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case 3:
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k1 ^= data[tail + 2] << 16;
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case 2:
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k1 ^= data[tail + 1] << 8;
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case 1:
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k1 ^= data[tail + 0];
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k1 = mul32(k1, c1);
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k1 = rotl32(k1, 15);
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k1 = mul32(k1, c2);
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h1 ^= k1;
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}
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h1 ^= data.length;
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h1 ^= h1 >>> 16;
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h1 = mul32(h1, 0x85ebca6b);
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h1 ^= h1 >>> 13;
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h1 = mul32(h1, 0xc2b2ae35);
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h1 ^= h1 >>> 16;
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if (h1 < 0)
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h1 += 0x100000000;
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return h1;
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}
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if (native)
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murmur3 = native.murmur3;
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function mul32(a, b) {
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var alo = a & 0xffff;
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var blo = b & 0xffff;
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var ahi = a >>> 16;
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var bhi = b >>> 16;
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var r, lo, hi;
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lo = alo * blo;
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hi = (ahi * blo + bhi * alo) & 0xffff;
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hi += lo >>> 16;
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lo &= 0xffff;
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r = (hi << 16) | lo;
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if (r < 0)
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r += 0x100000000;
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return r;
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}
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function sum32(a, b) {
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var r = (a + b) & 0xffffffff;
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if (r < 0)
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r += 0x100000000;
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return r;
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}
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function rotl32(w, b) {
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return (w << b) | (w >>> (32 - b));
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}
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/**
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* Expose
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*/
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exports = murmur3;
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exports.murmur3 = murmur3;
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exports.mul32 = mul32;
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exports.sum32 = sum32;
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exports.rotl32 = rotl32;
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module.exports = exports;
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