swi вызовы в gcc

__inline__ int swi(int i, int p)
{
	register int pp __asm__("r1") = p;
	register int res __asm__("r0");
	__asm__ volatile ("swi 0x12345" : "=r"(res) : "0"(i), "r"(pp));
	return res;
}

int main()
{
	int a = 2; 
	int b = 5;
	return swi(a, b);
}

0000000c <swi>:
   c:   ef012345        svc     0x00012345
  10:   e12fff1e        bx      lr

00000014 <main>:
  14:   e3a01005        mov     r1, #5
  18:   e3a00002        mov     r0, #2
  1c:   ef012345        svc     0x00012345
  20:   e12fff1e        bx      lr