typedfastbitset/lib/utils.js

Speed-optimized BitSet implementation for modern browsers and JavaScript engines, using typed arrays

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.hammingWeight4 = exports.hammingWeight = void 0;
// fast function to compute the Hamming weight of a 32-bit unsigned integer
function hammingWeight(v) {
    v -= (v >>> 1) & 0x55555555; // works with signed or unsigned shifts
    v = (v & 0x33333333) + ((v >>> 2) & 0x33333333);
    return (((v + (v >>> 4)) & 0xf0f0f0f) * 0x1010101) >>> 24;
}
exports.hammingWeight = hammingWeight;
// fast function to compute the Hamming weight of four 32-bit unsigned integers
function hammingWeight4(v1, v2, v3, v4) {
    v1 -= (v1 >>> 1) & 0x55555555; // works with signed or unsigned shifts
    v2 -= (v2 >>> 1) & 0x55555555; // works with signed or unsigned shifts
    v3 -= (v3 >>> 1) & 0x55555555; // works with signed or unsigned shifts
    v4 -= (v4 >>> 1) & 0x55555555; // works with signed or unsigned shifts
    v1 = (v1 & 0x33333333) + ((v1 >>> 2) & 0x33333333);
    v2 = (v2 & 0x33333333) + ((v2 >>> 2) & 0x33333333);
    v3 = (v3 & 0x33333333) + ((v3 >>> 2) & 0x33333333);
    v4 = (v4 & 0x33333333) + ((v4 >>> 2) & 0x33333333);
    v1 = (v1 + (v1 >>> 4)) & 0xf0f0f0f;
    v2 = (v2 + (v2 >>> 4)) & 0xf0f0f0f;
    v3 = (v3 + (v3 >>> 4)) & 0xf0f0f0f;
    v4 = (v4 + (v4 >>> 4)) & 0xf0f0f0f;
    return ((v1 + v2 + v3 + v4) * 0x1010101) >>> 24;
}
exports.hammingWeight4 = hammingWeight4;
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