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
8 static const double_t toint = 1/EPS;
9 
ceil(double x)10 double ceil(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 ? -0.0 : 1;
27 	}
28 	if (y < 0)
29 		return x + y + 1;
30 	return x + y;
31 }
32