glibc/sysdeps/ieee754/ldbl-128/s_logbl.c
Paul E. Murphy 15089e046b ldbl-128: Rename 'long double' to '_Float128'
Add a layer of macro indirection for long double files
which need to be built using another typename.  Likewise,
add the L(num) macro used in a later patch to override
real constants.

These macros are only defined through the ldbl-128
math_ldbl.h header, thereby implicitly restricting
these macros to machines which back long double
with an IEEE binary128 format.

Likewise, appropriate changes are made for the few
files which indirectly include such ldbl-128 files.

These changes produce identical binaries for s390x,
aarch64, and ppc64.
2016-08-31 10:38:11 -05:00

55 lines
1.3 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>
_Float128
__logbl (_Float128 x)
{
int64_t lx, hx, ex;
GET_LDOUBLE_WORDS64 (hx, lx, x);
hx &= 0x7fffffffffffffffLL; /* high |x| */
if ((hx | lx) == 0)
return -1.0 / fabsl (x);
if (hx >= 0x7fff000000000000LL)
return x * x;
if ((ex = hx >> 48) == 0) /* IEEE 754 logb */
{
/* POSIX specifies that denormal number is treated as
though it were normalized. */
int ma;
if (hx == 0)
ma = __builtin_clzll (lx) + 64;
else
ma = __builtin_clzll (hx);
ex -= ma - 16;
}
return (_Float128) (ex - 16383);
}
weak_alias (__logbl, logbl)