mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-24 22:10:13 +00:00
2e2485ce05
This patch is using the corresponding GCC builtin for logbf, logb, logbl and logbf128 if the USE_FUNCTION_BUILTIN macros are defined to one in math-use-builtins-function.h. Co-Authored-By: Xi Ruoyao <xry111@xry111.site>
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/* s_logbl.c -- long double version of s_logb.c.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* 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 <libm-alias-ldouble.h>
|
|
#include <math-use-builtins.h>
|
|
|
|
_Float128
|
|
__logbl (_Float128 x)
|
|
{
|
|
#if USE_LOGBL_BUILTIN
|
|
return __builtin_logbl (x);
|
|
#else
|
|
/* Use generic implementation. */
|
|
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);
|
|
#endif /* ! USE_LOGBL_BUILTIN */
|
|
}
|
|
|
|
libm_alias_ldouble (__logb, logb)
|