count

Counts no. of true values. 📦 😺 🏃 📼 🌔 📜 📰 📘

Can be used to implement one-hot / one-cold detector.

count([a], [b], [c], [d], [e], [f], [g], [h])
// a: 1st boolean
// b: 2nd boolean
// c: 3rd boolean
// d: 4th boolean
// e: 5th boolean
// f: 6th boolean
// g: 7th boolean
// h: 8th boolean

const {count} = require("extra-boolean");

count(true, true);
// 2

count(true, false);
// 1

count(true, true, true, false);
// 3           ^     ^     ^

count(false, true, false, false);
// 1                  ^

References

• Parallel method: Bit Twiddling Hacks
• bit-twiddle: @mikolalysenko
• count-bits: @DenQ
• popcnt32: @emilbayes