mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-21 04:31:04 +08:00
48 lines
1.2 KiB
C
48 lines
1.2 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"
|
||
|
|
#include <math_ldbl_opt.h>
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
long double __logbl(long double x)
|
||
|
|
#else
|
||
|
|
long double __logbl(x)
|
||
|
|
long double x;
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
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);
|