1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
/* s_scalbnl.c -- long double version of s_scalbn.c.
* Conversion to long double by Ulrich Drepper,
* Cygnus Support, drepper@cygnus.com.
*/
/*
* ====================================================
* 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
/*
* scalbnl (long double x, int n)
* scalbnl(x,n) returns x* 2**n computed by exponent
* manipulation rather than by actually performing an
* exponentiation or a multiplication.
*/
#include "math.h"
#include "math_private.h"
#ifdef __STDC__
static const long double
#else
static long double
#endif
two63 = 4.50359962737049600000e+15,
twom63 = 1.08420217248550443400e-19,
huge = 1.0e+4900L,
tiny = 1.0e-4900L;
#ifdef __STDC__
long double __scalbnl (long double x, int n)
#else
long double __scalbnl (x,n)
long double x; int n;
#endif
{
int32_t k,es,hx,lx;
GET_LDOUBLE_WORDS(es,hx,lx,x);
k = es&0x7fff; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two63;
GET_LDOUBLE_EXP(es,x);
k = (hx&0x7fff) - 63;
}
if (k==0x7fff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0x7ffe)
return huge*__copysignl(huge,x); /* overflow */
if (n< -50000)
return tiny*__copysignl(tiny,x);
if (k > 0) /* normal result */
{SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
if (k <= -63)
return tiny*__copysignl(tiny,x); /*underflow*/
k += 54; /* subnormal result */
SET_LDOUBLE_EXP(x,(es&0x8000)|k);
return x*twom63;
}
weak_alias (__scalbnl, scalbnl)
|
