code: function fillBitreversedTable(tab, fftSize) {
    let log_size, i;
  
    for (log_size = -1, i = fftSize; i; i >>= 1, log_size++)
    ;
  
    for (i = 0; i < fftSize; i++) {
      let idx = i;
      let xdi = 0;
  
      for (let j = 1; j < log_size; j++) {
        xdi += (idx & 1);
        xdi <<= 1;
        idx >>= 1;
      }
  
      tab[i] = xdi + (idx & 1);
    }
  
    return tab;
  }
docs: tab = Uint32Array(fftSize)