code: private void writeUShort(int s) {
          byte b1 = (byte)((s >> 8) & 0xff);
          byte b2 = (byte)(s & 0xff);
          writeByte(b1);
          writeByte(b2);
      }
docs: Appends a USHORT to the output array,
  updates currentPost but not realSize
  
  @param s The short to write