binary.js

//Hamming weight
export const getBitCount32 = (n) => {
  n = n - ((n >> 1) & 0x55555555);
  n = (n & 0x33333333) + ((n >> 2) & 0x33333333);
  return ((n + (n >> 4) & 0xF0F0F0F) * 0x1010101) >> 24; 
}

export const getBitCount = (n) => {
  let str = n.toString(2), count = 0;
  for (let i = str.length - 1; i >= 0; i--) {
    if (str[i] === "1") ++count;
  }
  return count;
}

//returns from left (0) to right(n) by position(0-n)
//step 1: binary left shift eg: x = 110100000 p = 1 -> 000000011
//step 2: binary and 1: 000000011 & 000000001 -> 000000001
export const getLeftPosition = (value, position) => {
  return (((value >> (8 - position)) & 1) == 1); 
}

//its same as: value + Math.pow(2, 8 - position);
export const addLeftPosition = (value, position) => { 
  return value | (1 << (8 - position));
}