summaryrefslogtreecommitdiff
path: root/src/math/ilogbl.c
blob: ed9ddcbc42582ac0fb2c0ab5923a0bccb6ccd050 (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
#include <limits.h>
#include "libm.h"

#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
int ilogbl(long double x)
{
	return ilogb(x);
}
#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
int ilogbl(long double x)
{
	union ldshape u = {x};
	uint64_t m = u.bits.m;
	int e = u.bits.exp;

	if (!e) {
		if (m == 0)
			return FP_ILOGB0;
		/* subnormal x */
		for (e = -0x3fff+1; m < (uint64_t)1<<63; e--, m<<=1);
		return e;
	}
	if (e == 0x7fff)
		/* in ld80 msb is set in inf */
		return m & (uint64_t)-1>>1 ? FP_ILOGBNAN : INT_MAX;
	return e - 0x3fff;
}
#endif