1#include "libm.h"
2
3#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
4#define EPS DBL_EPSILON
5#elif FLT_EVAL_METHOD==2
6#define EPS LDBL_EPSILON
7#endif
8static const double_t toint = 1/EPS;
9
10double round(double x)
11{
12	union {double f; uint64_t i;} u = {x};
13	int e = u.i >> 52 & 0x7ff;
14	double_t y;
15
16	if (e >= 0x3ff+52)
17		return x;
18	if (u.i >> 63)
19		x = -x;
20	if (e < 0x3ff-1) {
21		/* raise inexact if x!=0 */
22		FORCE_EVAL(x + toint);
23		return 0*u.f;
24	}
25	y = x + toint - toint - x;
26	if (y > 0.5)
27		y = y + x - 1;
28	else if (y <= -0.5)
29		y = y + x + 1;
30	else
31		y = y + x;
32	if (u.i >> 63)
33		y = -y;
34	return y;
35}
36