summary refs log tree commit diff
path: root/sysdeps/libm-ieee754/s_ilogbl.c
blob: d44229dcdac44e170daa844ea5fd433ceae5a610 (plain) (blame)
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
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
/* s_ilogbl.c -- long double version of s_ilogb.c.
 * Conversion to long double by Ulrich Drepper,
 * Cygnus Support, drepper@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: $";
#endif

/* ilogbl(long double x)
 * return the binary exponent of non-zero x
 * ilogbl(0) = 0x80000001
 * ilogbl(inf/NaN) = 0x7fffffff (no signal is raised)
 */

#include "math.h"
#include "math_private.h"

#ifdef __STDC__
	int __ilogbl(long double x)
#else
	int __ilogbl(x)
	long double x;
#endif
{
	int32_t es,hx,lx,ix;

	GET_LDOUBLE_EXP(es,x);
	es &= 0x7fff;
	if(es==0) {
	    GET_LDOUBLE_WORDS(es,hx,lx,x);
	    if((hx|lx)==0)
		return FP_ILOGB0;	/* ilogbl(0) = FP_ILOGB0 */
	    else			/* subnormal x */
		if(hx==0) {
		    for (ix = -16415; lx>0; lx<<=1) ix -=1;
		} else {
		    for (ix = -16383; hx>0; hx<<=1) ix -=1;
		}
	    return ix;
	}
	else if (es<0x7fff) return es-0x3fff;
	else return FP_ILOGBNAN;
}
weak_alias (__ilogbl, ilogbl)