#include <avr/io.h>

#define loop_until_mybit_is_clear(port,bit)  \
        __asm__ __volatile__ (             \
        "L_%=: " "sbic %0, %1" "\n\t"      \
                 "rjmp L_%="               \
                 :  /* no outputs */       \
				 : "I" (_SFR_IO_ADDR(port)), "I" (bit)  \
        )

int main(){
    uint8_t bit=7;
	loop_until_mybit_is_clear(PORTD,bit);
	loop_until_mybit_is_clear(PORTB,bit);
}