1 /* s_scalbnl.c -- long double version of s_scalbn.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
5 /* @(#)s_scalbn.c 5.1 93/09/24 */
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
14 * ====================================================
17 #if defined(LIBM_SCCS) && !defined(lint)
18 static char rcsid
[] = "$NetBSD: $";
22 * scalbnl (long double x, int n)
23 * scalbnl(x,n) returns x* 2**n computed by exponent
24 * manipulation rather than by actually performing an
25 * exponentiation or a multiplication.
29 #include <math_private.h>
31 static const _Float128
32 two114
= L(2.0769187434139310514121985316880384E+34), /* 0x4071000000000000, 0 */
33 twom114
= L(4.8148248609680896326399448564623183E-35), /* 0x3F8D000000000000, 0 */
37 _Float128
__scalbnl (_Float128 x
, int n
)
40 GET_LDOUBLE_WORDS64(hx
,lx
,x
);
41 k
= (hx
>>48)&0x7fff; /* extract exponent */
42 if (k
==0) { /* 0 or subnormal x */
43 if ((lx
|(hx
&0x7fffffffffffffffULL
))==0) return x
; /* +-0 */
45 GET_LDOUBLE_MSW64(hx
,x
);
46 k
= ((hx
>>48)&0x7fff) - 114;
48 if (k
==0x7fff) return x
+x
; /* NaN or Inf */
49 if (n
< -50000) return tiny
*__copysignl(tiny
,x
); /*underflow*/
50 if (n
> 50000 || k
+n
> 0x7ffe)
51 return huge
*__copysignl(huge
,x
); /* overflow */
52 /* Now k and n are bounded we know that k = k+n does not
55 if (k
> 0) /* normal result */
56 {SET_LDOUBLE_MSW64(x
,(hx
&0x8000ffffffffffffULL
)|(k
<<48)); return x
;}
58 return tiny
*__copysignl(tiny
,x
); /*underflow*/
59 k
+= 114; /* subnormal result */
60 SET_LDOUBLE_MSW64(x
,(hx
&0x8000ffffffffffffULL
)|(k
<<48));