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/*
* From: @(#)s_ilogb.c 5.1 93/09/24
* ====================================================
* 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.
* ====================================================
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <float.h>
#include <limits.h>
#include <math.h>
#include "fpmath.h"
long double
logbl(long double x)
{
union IEEEl2bits u;
unsigned long m;
int b;
u.e = x;
if (u.bits.exp == 0) {
if ((u.bits.manl | u.bits.manh) == 0) { /* x == 0 */
u.bits.sign = 1;
return (1.0L / u.e);
}
/* denormalized */
if (u.bits.manh == 0) {
m = 1lu << (LDBL_MANL_SIZE - 1);
for (b = LDBL_MANH_SIZE; !(u.bits.manl & m); m >>= 1)
b++;
} else {
m = 1lu << (LDBL_MANH_SIZE - 1);
for (b = 0; !(u.bits.manh & m); m >>= 1)
b++;
}
#ifdef LDBL_IMPLICIT_NBIT
b++;
#endif
return ((long double)(LDBL_MIN_EXP - b - 1));
}
if (u.bits.exp < (LDBL_MAX_EXP << 1) - 1) /* normal */
return ((long double)(u.bits.exp - LDBL_MAX_EXP + 1));
else /* +/- inf or nan */
return (x * x);
}
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