code: private boolean subArraysEqualWithMask(byte[] a, int aStart, byte[] b, int bStart, byte[] mask, int maskStart, int len) {
          for (int i = aStart, j = bStart, k = maskStart; len > 0; i++, j++, k++, len--) {
              if ((a[i] & mask[k]) != (b[j] & mask[k])) {
                  return false;
              }
          }
  
          return true;
      }
docs: Returns true if subarrays are equal, with the given mask.
  
  <p>
  The mask must have length <tt>len</tt>.
  </p>