static __inline__ uint8_t
_crc8_ccitt_update(uint8_t __crc, uint8_t __data)
{
    uint8_t __i, __pattern;
    __asm__ __volatile__ (
        "    eor    %0, %4" "\n\t"
        "    ldi    %1, 8" "\n\t"
        "    ldi    %2, 0x07" "\n\t"
        "1:  lsl    %0" "\n\t"
        "    brcc   2f" "\n\t"
        "    eor    %0, %2" "\n\t"
        "2:  dec    %1" "\n\t"
        "    brne   1b" "\n\t"
        : "=r" (__crc), "=d" (__i), "=d" (__pattern)
        : "0" (__crc), "r" (__data));
    return __crc;
}