149 lines
2.9 KiB
JavaScript
149 lines
2.9 KiB
JavaScript
var bcoin = require('../bcoin');
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var utils = bcoin.utils;
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function Bloom(size, n, tweak) {
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if (!(this instanceof Bloom))
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return new Bloom(size, n, tweak);
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this.filter = new Array(Math.ceil(size / 32));
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this.size = size;
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this.n = n;
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this.tweak = tweak;
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this.reset();
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}
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module.exports = Bloom;
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Bloom.prototype.hash = function hash(val, n) {
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return Bloom.hash(val, sum32(mul32(n, 0xfba4c795), this.tweak)) % this.size;
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};
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Bloom.prototype.reset = function reset() {
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for (var i = 0; i < this.filter.length; i++)
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this.filter[i] = 0;
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};
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Bloom.prototype.add = function add(val, enc) {
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val = utils.toArray(val, enc);
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for (var i = 0; i < this.n; i++) {
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var bit = this.hash(val, i);
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var pos = 1 << (bit & 0x1f);
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var shift = bit >> 5;
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this.filter[shift] |= pos;
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}
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};
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Bloom.prototype.test = function test(val, enc) {
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val = utils.toArray(val, enc);
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for (var i = 0; i < this.n; i++) {
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var bit = this.hash(val, i);
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var pos = 1 << (bit & 0x1f);
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var shift = bit >> 5;
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if ((this.filter[shift] & pos) === 0)
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return false;
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}
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return true;
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};
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Bloom.prototype.toArray = function toArray() {
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var bytes = Math.ceil(this.size / 8);
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var res = new Array(this.filter.length * 4);
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for (var i = 0; i < this.filter.length; i++) {
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var w = this.filter[i];
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res[i * 4] = w & 0xff;
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res[i * 4 + 1] = (w >> 8) & 0xff;
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res[i * 4 + 2] = (w >> 16) & 0xff;
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res[i * 4 + 3] = (w >> 24) & 0xff;
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}
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return res.slice(0, bytes);
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};
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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 lo = alo * blo;
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var hi = (ahi * blo + bhi * alo) & 0xffff;
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hi += lo >>> 16;
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lo &= 0xffff;
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var 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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function hash(data, seed) {
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data = utils.toArray(data);
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var c1 = 0xcc9e2d51;
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var c2 = 0x1b873593;
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var r1 = 15;
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var r2 = 13;
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var m = 5;
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var n = 0xe6546b64;
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var hash = seed;
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for (var i = 0; i + 4 <= data.length; i += 4) {
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var w = data[i] |
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(data[i + 1] << 8) |
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(data[i + 2] << 16) |
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(data[i + 3] << 24);
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w = mul32(w, c1);
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w = rotl32(w, r1);
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w = mul32(w, c2);
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hash ^= w;
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hash = rotl32(hash, r2);
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hash = mul32(hash, m);
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hash = sum32(hash, n);
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}
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if (i !== data.length) {
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var r = 0;
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for (var j = data.length - 1; j >= i; j--)
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r = (r << 8) | data[j];
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r = mul32(r, c1);
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r = rotl32(r, r1);
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if (r < 0)
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r += 0x100000000;
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r = mul32(r, c2);
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hash ^= r;
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}
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hash ^= data.length;
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hash ^= hash >>> 16;
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hash = mul32(hash, 0x85ebca6b);
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hash ^= hash >>> 13;
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hash = mul32(hash, 0xc2b2ae35);
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hash ^= hash >>> 16;
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if (hash < 0)
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hash += 0x100000000;
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return hash;
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}
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Bloom.hash = hash;
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