code: private final void set(int i) {   
          setASCIItextDirty(i);
          setASCIIattrDirty(i); 
               
          int j = (i >> SHIFT_PER_WORD); // this word is used
          int k = j + 1;       
          
          if(firstWordNotUsed < k) // for optimization purposes.
              firstWordNotUsed = k;
              
          array_of_bits[j] |= (1 << (i & LOW_ORDER_BITMASK));
      }
docs: Adds the integer (character) to the set of integers.
  @param i the integer to add to the set, valid values are
  0, 1, 2 ... up to the maximum that was specified at
  the creation of the set.