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/* s_frexpl.c -- long double version of s_frexp.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
/*
* for non-zero x
* x = frexpl(arg,&exp);
* return a long double fp quantity x such that 0.5 <= |x| <1.0
* and the corresponding binary exponent "exp". That is
* arg = x*2^exp.
* If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
* with *exp=0.
*/
#include <math.h>
#include <math_private.h>
#include <math_ldbl_opt.h>
long double __frexpl(long double x, int *eptr)
{
uint64_t hx, lx, ix, ixl;
int64_t explo, expon;
double xhi, xlo;
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
EXTRACT_WORDS64 (lx, xlo);
ixl = 0x7fffffffffffffffULL & lx;
ix = 0x7fffffffffffffffULL & hx;
expon = 0;
if (ix >= 0x7ff0000000000000ULL || ix == 0)
{
/* 0,inf,nan. */
*eptr = expon;
return x + x;
}
expon = ix >> 52;
if (expon == 0)
{
/* Denormal high double, the low double must be 0.0. */
int cnt;
/* Normalize. */
if (sizeof (ix) == sizeof (long))
cnt = __builtin_clzl (ix);
else if ((ix >> 32) != 0)
cnt = __builtin_clzl ((long) (ix >> 32));
else
cnt = __builtin_clzl ((long) ix) + 32;
cnt = cnt - 12;
expon -= cnt;
ix <<= cnt + 1;
}
expon -= 1022;
ix &= 0x000fffffffffffffULL;
hx &= 0x8000000000000000ULL;
hx |= (1022LL << 52) | ix;
if (ixl != 0)
{
/* If the high double is an exact power of two and the low
double has the opposite sign, then the exponent calculated
from the high double is one too big. */
if (ix == 0
&& (int64_t) (hx ^ lx) < 0)
{
hx += 1LL << 52;
expon -= 1;
}
explo = ixl >> 52;
if (explo == 0)
{
/* The low double started out as a denormal. Normalize its
mantissa and adjust the exponent. */
int cnt;
if (sizeof (ixl) == sizeof (long))
cnt = __builtin_clzl (ixl);
else if ((ixl >> 32) != 0)
cnt = __builtin_clzl ((long) (ixl >> 32));
else
cnt = __builtin_clzl ((long) ixl) + 32;
cnt = cnt - 12;
explo -= cnt;
ixl <<= cnt + 1;
}
/* With variable precision we can't assume much about the
magnitude of the returned low double. It may even be a
denormal. */
explo -= expon;
ixl &= 0x000fffffffffffffULL;
lx &= 0x8000000000000000ULL;
if (explo <= 0)
{
/* Handle denormal low double. */
if (explo > -52)
{
ixl |= 1LL << 52;
ixl >>= 1 - explo;
}
else
{
ixl = 0;
lx = 0;
if ((hx & 0x7ff0000000000000ULL) == (1023LL << 52))
{
/* Oops, the adjustment we made above for values a
little smaller than powers of two turned out to
be wrong since the returned low double will be
zero. This can happen if the input was
something weird like 0x1p1000 - 0x1p-1000. */
hx -= 1LL << 52;
expon += 1;
}
}
explo = 0;
}
lx |= (explo << 52) | ixl;
}
INSERT_WORDS64 (xhi, hx);
INSERT_WORDS64 (xlo, lx);
x = ldbl_pack (xhi, xlo);
*eptr = expon;
return x;
}
#if IS_IN (libm)
long_double_symbol (libm, __frexpl, frexpl);
#else
long_double_symbol (libc, __frexpl, frexpl);
#endif
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