_x128_t 编译这段程序，出现错误，如何改正谢谢

#include <c6x.h>
#include <stdio.h>

_x128_t mpy_four_way_example(_x128_t s, int a, int b, int c, int d)
{
_x128_t t=_ito128(a, b, c, d);
_x128_t results=_qmpy32(s,t);

int lowest32=_get32_128(results, 0);
int highest32=_get32_128(results, 0);

printf("lowest=%d\n",lowest32);
printf("highest=%d\n",highest32);
return results;
}