gistfile1.c

static int sadd(int a, int b)
{
	asm (
		"addl %1, %0\n\t"
		"jo 1f\n\t"
		"jmp 4f\n\t"
		"1: js 2f\n\t"
		"jmp 3f\n\t"
		"2: movl $0x7fffffff, %0\n\t"
		"jmp 4f\n\t"
		"3: movl $~0, %0\n\t"
		"4:"
		: "=r"(a)
		: "r"(b), "0"(a)
		: "flags"
	);
	return a;
}