1#include "libm.h"
 2
 3double modf(double x, double *iptr)
 4{
 5	union {double f; uint64_t i;} u = {x};
 6	uint64_t mask;
 7	int e = (int)(u.i>>52 & 0x7ff) - 0x3ff;
 8
 9	/* no fractional part */
10	if (e >= 52) {
11		*iptr = x;
12		if (e == 0x400 && u.i<<12 != 0) /* nan */
13			return x;
14		u.i &= 1ULL<<63;
15		return u.f;
16	}
17
18	/* no integral part*/
19	if (e < 0) {
20		u.i &= 1ULL<<63;
21		*iptr = u.f;
22		return x;
23	}
24
25	mask = -1ULL>>12>>e;
26	if ((u.i & mask) == 0) {
27		*iptr = x;
28		u.i &= 1ULL<<63;
29		return u.f;
30	}
31	u.i &= ~mask;
32	*iptr = u.f;
33	return x - u.f;
34}