Question

How to extract N bits from a given position in a number with JavaScript

Answer 1

function extract_bits(number, N, pos) {
    return (((1 << N) - 1) & (number >> (pos - 1)));
}

const number = 441; // 000000-011011-1001
const N = 6;
const pos = 5;

console.log(("0000000000000000" + number.toString(2)).substr(-16));

let extracted_bits = extract_bits(number, N, pos);

console.log(("0000000000000000" + extracted_bits.toString(2)).substr(-16));





/*
run:
     
0000000110111001
0000000000011011
     
*/

 

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