crc16 AVR MCU

static __inline__ uint16_t

_crc16_update(uint16_t __crc, uint8_t __data)

{

        uint8_t __tmp;

        uint16_t __ret;



        __asm__ __volatile__ (

                "eor %A0,%2" "\n\t"

                "mov %1,%A0" "\n\t"

                "swap %1" "\n\t"

                "eor %1,%A0" "\n\t"

                "mov __tmp_reg__,%1" "\n\t"

                "lsr %1" "\n\t"

                "lsr %1" "\n\t"

                "eor %1,__tmp_reg__" "\n\t"

                "mov __tmp_reg__,%1" "\n\t"

                "lsr %1" "\n\t"

                "eor %1,__tmp_reg__" "\n\t"

                "andi %1,0x07" "\n\t"

                "mov __tmp_reg__,%A0" "\n\t"

                "mov %A0,%B0" "\n\t"

                "lsr %1" "\n\t"

                "ror __tmp_reg__" "\n\t"

                "ror %1" "\n\t"

                "mov %B0,__tmp_reg__" "\n\t"

                "eor %A0,%1" "\n\t"

                "lsr __tmp_reg__" "\n\t"

                "ror %1" "\n\t"

                "eor %B0,__tmp_reg__" "\n\t"

                "eor %A0,%1"

                : "=r" (__ret), "=d" (__tmp)

                : "r" (__data), "0" (__crc)

                : "r0"

        );  

        return __ret;

}