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bloomfilter.js
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Minor optimisation.

This commit is contained in:
Jason Davies 2011-09-04 19:19:12 +01:00
parent a6d3ebf281
commit f68498701f
1 changed files with 9 additions and 7 deletions
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bloomfilter.js
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@ -2,10 +2,10 @@
function BloomFilter(m, k) { function BloomFilter(m, k) {
this.m = m; this.m = m;
this.k = k; this.k = k;
this.buckets = []; var buckets = this.buckets = [],
var n = Math.ceil(m / k), n = Math.ceil(m / k),
i = -1; i = -1;
while (++i < n) this.buckets[i] = 0; while (++i < n) buckets[i] = 0;
} }
// See http://willwhim.wordpress.com/2011/09/03/producing-n-hash-functions-by-hashing-only-once/ // See http://willwhim.wordpress.com/2011/09/03/producing-n-hash-functions-by-hashing-only-once/
@ -34,8 +34,9 @@
BloomFilter.prototype.add = function(v) { BloomFilter.prototype.add = function(v) {
var l = this.locations(v), var l = this.locations(v),
i = -1, i = -1,
k = this.k; k = this.k,
while (++i < k) this.buckets[Math.floor(l[i] / k)] |= 1 << (l[i] % k) buckets = this.buckets;
while (++i < k) buckets[Math.floor(l[i] / k)] |= 1 << (l[i] % k)
}; };
BloomFilter.prototype.test = function(v) { BloomFilter.prototype.test = function(v) {
@ -43,10 +44,11 @@
n = l.length, n = l.length,
i = -1, i = -1,
k = this.k, k = this.k,
b; b,
buckets = this.buckets;
while (++i < n) { while (++i < n) {
b = l[i]; b = l[i];
if ((this.buckets[Math.floor(b / k)] & (1 << (b % k))) === 0) { if ((buckets[Math.floor(b / k)] & (1 << (b % k))) === 0) {
return false; return false;
} }
} }