Hi, I ended up constructing a binary() fct and usig masks and longs. I used longs because I remarked that: >>> 0x100000000&0xFFFF0000>>16 4294967296L ?? This si probably due to the 32 bit integer limit you told me about, because: >>> 0x100000000&0xFFFF0000L>>16 0L Thank you for your answers! Guille