2006-01-28 00:15:15 +00:00
|
|
|
/* s_scalblnl.c -- long double version of s_scalbln.c.
|
|
|
|
|
* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
/* @(#)s_scalbln.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.
|
|
|
|
|
* ====================================================
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
|
|
|
static char rcsid[] = "$NetBSD: $";
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* scalblnl (long double x, long int n)
|
|
|
|
|
* scalblnl(x,n) returns x* 2**n computed by exponent
|
|
|
|
|
* manipulation rather than by actually performing an
|
|
|
|
|
* exponentiation or a multiplication.
|
|
|
|
|
*/
|
|
|
|
|
|
2012-03-09 19:29:16 +00:00
|
|
|
#include <math.h>
|
|
|
|
|
#include <math_private.h>
|
2006-01-28 00:15:15 +00:00
|
|
|
#include <math_ldbl_opt.h>
|
|
|
|
|
|
|
|
|
|
static const long double
|
|
|
|
|
twolm54 = 5.55111512312578270212e-17, /* 0x3C90000000000000, 0 */
|
|
|
|
|
huge = 1.0E+300L,
|
|
|
|
|
tiny = 1.0E-300L;
|
|
|
|
|
static const double
|
|
|
|
|
two54 = 1.80143985094819840000e+16, /* 0x4350000000000000 */
|
|
|
|
|
twom54 = 5.55111512312578270212e-17; /* 0x3C90000000000000 */
|
|
|
|
|
|
2012-01-27 17:27:55 +00:00
|
|
|
long double __scalblnl (long double x, long int n)
|
2006-01-28 00:15:15 +00:00
|
|
|
{
|
|
|
|
|
int64_t k,l,hx,lx;
|
|
|
|
|
union { int64_t i; double d; } u;
|
|
|
|
|
GET_LDOUBLE_WORDS64(hx,lx,x);
|
|
|
|
|
k = (hx>>52)&0x7ff; /* extract exponent */
|
|
|
|
|
l = (lx>>52)&0x7ff;
|
|
|
|
|
if (k==0) { /* 0 or subnormal x */
|
|
|
|
|
if (((hx|lx)&0x7fffffffffffffffULL)==0) return x; /* +-0 */
|
|
|
|
|
u.i = hx;
|
|
|
|
|
u.d *= two54;
|
|
|
|
|
hx = u.i;
|
|
|
|
|
k = ((hx>>52)&0x7ff) - 54;
|
|
|
|
|
}
|
|
|
|
|
else if (k==0x7ff) return x+x; /* NaN or Inf */
|
|
|
|
|
if (n< -50000) return tiny*__copysignl(tiny,x); /*underflow */
|
2012-03-02 15:32:56 +00:00
|
|
|
if (n> 50000 || k+n > 0x7fe)
|
|
|
|
|
return huge*__copysignl(huge,x); /* overflow */
|
|
|
|
|
/* Now k and n are bounded we know that k = k+n does not
|
|
|
|
|
overflow. */
|
|
|
|
|
k = k+n;
|
2006-01-28 00:15:15 +00:00
|
|
|
if (k > 0) { /* normal result */
|
|
|
|
|
hx = (hx&0x800fffffffffffffULL)|(k<<52);
|
|
|
|
|
if ((lx & 0x7fffffffffffffffULL) == 0) { /* low part +-0 */
|
|
|
|
|
SET_LDOUBLE_WORDS64(x,hx,lx);
|
|
|
|
|
return x;
|
|
|
|
|
}
|
|
|
|
|
if (l == 0) { /* low part subnormal */
|
|
|
|
|
u.i = lx;
|
|
|
|
|
u.d *= two54;
|
|
|
|
|
lx = u.i;
|
|
|
|
|
l = ((lx>>52)&0x7ff) - 54;
|
|
|
|
|
}
|
|
|
|
|
l = l + n;
|
|
|
|
|
if (l > 0)
|
|
|
|
|
lx = (lx&0x800fffffffffffffULL)|(l<<52);
|
|
|
|
|
else if (l <= -54)
|
|
|
|
|
lx = (lx&0x8000000000000000ULL);
|
|
|
|
|
else {
|
|
|
|
|
l += 54;
|
|
|
|
|
u.i = (lx&0x800fffffffffffffULL)|(l<<52);
|
|
|
|
|
u.d *= twom54;
|
|
|
|
|
lx = u.i;
|
|
|
|
|
}
|
|
|
|
|
SET_LDOUBLE_WORDS64(x,hx,lx);
|
|
|
|
|
return x;
|
|
|
|
|
}
|
|
|
|
|
if (k <= -54)
|
|
|
|
|
return tiny*__copysignl(tiny,x); /*underflow*/
|
|
|
|
|
k += 54; /* subnormal result */
|
|
|
|
|
lx &= 0x8000000000000000ULL;
|
|
|
|
|
SET_LDOUBLE_WORDS64(x,(hx&0x800fffffffffffffULL)|(k<<52),lx);
|
|
|
|
|
return x*twolm54;
|
|
|
|
|
}
|
|
|
|
|
long_double_symbol (libm, __scalblnl, scalblnl);
|
