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/* s_ilogbl.c -- long double version of s_ilogb.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
/* ilogbl(long double x)
* return the binary exponent of non-zero x
* ilogbl(0) = FP_ILOGB0
* ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
* ilogbl(+-Inf) = INT_MAX (no signal is raised)
*/
#include <limits.h>
#include <math.h>
#include <math_private.h>
#include <math_ldbl_opt.h>
int __ieee754_ilogbl(long double x)
{
int64_t hx, hxs;
int ix;
double xhi, xlo;
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
hxs = hx;
hx &= 0x7fffffffffffffffLL;
if(hx <= 0x0010000000000000LL) {
if(hx==0)
return FP_ILOGB0; /* ilogbl(0) = FP_ILOGB0 */
else /* subnormal x */
for (ix = -1022, hx<<=11; hx>0; hx<<=1) ix -=1;
return ix;
}
else if (hx < 0x7ff0000000000000LL)
{
int hexp = (hx >> 52) - 0x3ff;
/* 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. */
if ((hx & 0x000fffffffffffffLL) == 0)
{
int64_t lx;
EXTRACT_WORDS64 (lx, xlo);
if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)
hexp--;
}
return hexp;
}
else if (FP_ILOGBNAN != INT_MAX) {
/* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */
if (hx==0x7ff0000000000000LL)
return INT_MAX;
}
return FP_ILOGBNAN;
}
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