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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.
* ====================================================
*/
/*
* 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>
#include <fix-int-fp-convert-zero.h>
long double
__logbl (long double x)
{
int64_t hx, hxs, rhx;
double xhi, xlo;
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
hxs = hx;
hx &= 0x7fffffffffffffffLL; /* high |x| */
if (hx == 0)
return -1.0 / fabs (x);
if (hx >= 0x7ff0000000000000LL)
return x * x;
if (__glibc_unlikely ((rhx = hx >> 52) == 0))
{
/* POSIX specifies that denormal number is treated as
though it were normalized. */
rhx -= __builtin_clzll (hx) - 12;
}
else if ((hx & 0x000fffffffffffffLL) == 0)
{
/* If the high part is a power of 2, and the low part is nonzero
with the opposite sign, the low part affects the
exponent. */
int64_t lx;
EXTRACT_WORDS64 (lx, xlo);
if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)
rhx--;
}
if (FIX_INT_FP_CONVERT_ZERO && rhx == 1023)
return 0.0L;
return (long double) (rhx - 1023);
}
#ifndef __logbl
long_double_symbol (libm, __logbl, logbl);
#endif
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