glibc/sysdeps/ieee754/ldbl-128/s_logbl.c
2012-01-27 17:29:45 +00:00

42 lines
1.1 KiB
C

/* 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"
long double __logbl(long double x)
{
int64_t lx,hx;
GET_LDOUBLE_WORDS64(hx,lx,x);
hx &= 0x7fffffffffffffffLL; /* high |x| */
if((hx|lx)==0) return -1.0/fabs(x);
if(hx>=0x7fff000000000000LL) return x*x;
if((hx>>=48)==0) /* IEEE 754 logb */
return -16382.0;
else
return (long double) (hx-0x3fff);
}
weak_alias (__logbl, logbl)