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mscdex/bitCount.js

Created March 13, 2016 20:07
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Fastest bit counting for 32-bit numbers in javascript
Raw
bitCount.js
function bitCount(u) {
// https://blogs.msdn.microsoft.com/jeuge/2005/06/08/bit-fiddling-3/
const uCount = u - ((u >> 1) & 0o33333333333) - ((u >> 2) & 0o11111111111);
return ((uCount + (uCount >> 3)) & 0o30707070707) % 63;
}
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