docs: public static void onesI(long[] v, int bits) {
      final int fillWords = bits >>> LONG_LOG2_SIZE;
      final int fillBits = bits & LONG_LOG2_MASK;
      Arrays.fill(v, 0, fillWords, LONG_ALL_BITS);
      if(fillBits > 0) {
        v[fillWords] = (1L << fillBits) - 1;
      }
      if(fillWords + 1 < v.length) {
        Arrays.fill(v, fillWords + 1, v.length, 0L);
      }
    }