aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/ieee754/ldbl-128ibm/s_logbl.c
blob: 10ae684d1cb2aaae0902645363193f96984b98e7 (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
37
38
39
40
41
42
/* s_logbl.c -- long double version of s_logb.c.
 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
 */

/*
 * ====================================================
 * 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

/*
 * long double logbl(x)
 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
 * Use ilogb instead.
 */

#include "math.h"
#include "math_private.h"
#include <math_ldbl_opt.h>

long double __logbl(long double x)
{
	int64_t lx,hx;
	GET_LDOUBLE_WORDS64(hx,lx,x);
	hx &= 0x7fffffffffffffffLL;		/* high |x| */
	if((hx|(lx&0x7fffffffffffffffLL))==0) return -1.0/fabs(x);
	if(hx>=0x7ff0000000000000LL) return x*x;
	if((hx>>=52)==0) 			/* IEEE 754 logb */
		return -1022.0;
	else
		return (long double) (hx-0x3ff);
}
long_double_symbol (libm, __logbl, logbl);