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/* 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)
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