summaryrefslogtreecommitdiff
path: root/src/math/nextafterf.c
blob: 47775b92fd1db2c9c211fe0ea156d9ba10dc2276 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
#include "libm.h"

#define SIGN 0x80000000

float nextafterf(float x, float y)
{
	union fshape ux, uy;
	uint32_t ax, ay, e;

	if (isnan(x) || isnan(y))
		return x + y;
	ux.value = x;
	uy.value = y;
	if (ux.bits == uy.bits)
		return y;
	ax = ux.bits & ~SIGN;
	ay = uy.bits & ~SIGN;
	if (ax == 0) {
		if (ay == 0)
			return y;
		ux.bits = (uy.bits & SIGN) | 1;
	} else if (ax > ay || ((ux.bits ^ uy.bits) & SIGN))
		ux.bits--;
	else
		ux.bits++;
	e = ux.bits & 0x7f800000;
	/* raise overflow if ux.value is infinite and x is finite */
	if (e == 0x7f800000)
		return x + x;
	/* raise underflow if ux.value is subnormal or zero */
	if (e == 0) {
		volatile float z;
		z = x*x + ux.value*ux.value;
	}
	return ux.value;
}