1 #include "libm.h"
2 
trunc(double x)3 double trunc(double x)
4 {
5 	union {double f; uint64_t i;} u = {x};
6 	int e = (int)(u.i >> 52 & 0x7ff) - 0x3ff + 12;
7 	uint64_t m;
8 
9 	if (e >= 52 + 12)
10 		return x;
11 	if (e < 12)
12 		e = 1;
13 	m = -1ULL >> e;
14 	if ((u.i & m) == 0)
15 		return x;
16 	FORCE_EVAL(x + 0x1p120f);
17 	u.i &= ~m;
18 	return u.f;
19 }
20