51单片机多字节无符号数加减法运算源程序

#include<reg52.h>
#include<stdio.h>

extern serial_initial();

unsigned long x_at_0x30;
unsigned long y_at_0x40;

main()
{
serial_initial();
x=0XC9F21F;
y=0X881809;
y=x+y;
printf("y=%1X OR y=%ld\n",y,y);

while(1);
}