// swap macro exchanges operand values using exclusive or operator
#include <avr/io.h>
#define swap(a,b)({a^=b; b^=a; a^=b;})
volatile uint8_t m ;
volatile uint8_t n ;
/*
volatile char table[12];
volatile char * ptable = table;
*/
uint8_t foo(uint8_t bar){
	return(bar/2);
}
int main(){
    m=0x02;
   	n=0x07;
	swap(m,n);

}