1 /* s_scalbnl.c -- long double version of s_scalbn.c.
4 /* @(#)s_scalbn.c 5.1 93/09/24 */
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
16 #if defined(LIBM_SCCS) && !defined(lint)
17 static char rcsid
[] = "$NetBSD: $";
21 * scalbnl (long double x, int n)
22 * scalbnl(x,n) returns x* 2**n computed by exponent
23 * manipulation rather than by actually performing an
24 * exponentiation or a multiplication.
28 #include <math_private.h>
30 static const _Float128
31 two114
= L(2.0769187434139310514121985316880384E+34), /* 0x4071000000000000, 0 */
32 twom114
= L(4.8148248609680896326399448564623183E-35), /* 0x3F8D000000000000, 0 */
36 _Float128
__scalbnl (_Float128 x
, int n
)
39 GET_LDOUBLE_WORDS64(hx
,lx
,x
);
40 k
= (hx
>>48)&0x7fff; /* extract exponent */
41 if (k
==0) { /* 0 or subnormal x */
42 if ((lx
|(hx
&0x7fffffffffffffffULL
))==0) return x
; /* +-0 */
44 GET_LDOUBLE_MSW64(hx
,x
);
45 k
= ((hx
>>48)&0x7fff) - 114;
47 if (k
==0x7fff) return x
+x
; /* NaN or Inf */
48 if (n
< -50000) return tiny
*copysignl(tiny
,x
); /*underflow*/
49 if (n
> 50000 || k
+n
> 0x7ffe)
50 return huge
*copysignl(huge
,x
); /* overflow */
51 /* Now k and n are bounded we know that k = k+n does not
54 if (k
> 0) /* normal result */
55 {SET_LDOUBLE_MSW64(x
,(hx
&0x8000ffffffffffffULL
)|(k
<<48)); return x
;}
57 return tiny
*copysignl(tiny
,x
); /*underflow*/
58 k
+= 114; /* subnormal result */
59 SET_LDOUBLE_MSW64(x
,(hx
&0x8000ffffffffffffULL
)|(k
<<48));