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 floor(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 || x == 0)
17		return x;
18	/* y = int(x) - x, where int(x) is an integer neighbor of x */
19	if (u.i >> 63)
20		y = x - toint + toint - x;
21	else
22		y = x + toint - toint - x;
23	/* special case because of non-nearest rounding modes */
24	if (e <= 0x3ff-1) {
25		FORCE_EVAL(y);
26		return u.i >> 63 ? -1 : 0;
27	}
28	if (y > 0)
29		return x + y - 1;
30	return x + y;
31}
32