Update.
[glibc.git] / sysdeps / libm-ieee754 / s_scalbnl.c
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1 /* s_scalbnl.c -- long double version of s_scalbn.c.
2 * Conversion to long double by Ulrich Drepper,
3 * Cygnus Support, drepper@cygnus.com.
4 */
6 /*
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
13 * is preserved.
14 * ====================================================
17 #if defined(LIBM_SCCS) && !defined(lint)
18 static char rcsid[] = "$NetBSD: $";
19 #endif
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.
28 #include "math.h"
29 #include "math_private.h"
31 #ifdef __STDC__
32 static const long double
33 #else
34 static long double
35 #endif
36 two63 = 4.50359962737049600000e+15,
37 twom63 = 1.08420217248550443400e-19,
38 huge = 1.0e+4900L,
39 tiny = 1.0e-4900L;
41 #ifdef __STDC__
42 long double __scalbnl (long double x, int n)
43 #else
44 long double __scalbnl (x,n)
45 long double x; int n;
46 #endif
48 int32_t k,es,hx,lx;
49 GET_LDOUBLE_WORDS(es,hx,lx,x);
50 k = es&0x7fff; /* extract exponent */
51 if (k==0) { /* 0 or subnormal x */
52 if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
53 x *= two63;
54 GET_LDOUBLE_EXP(es,x);
55 k = (hx&0x7fff) - 63;
57 if (k==0x7fff) return x+x; /* NaN or Inf */
58 k = k+n;
59 if (n> 50000 || k > 0x7ffe)
60 return huge*__copysignl(huge,x); /* overflow */
61 if (n< -50000)
62 return tiny*__copysignl(tiny,x);
63 if (k > 0) /* normal result */
64 {SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
65 if (k <= -63)
66 return tiny*__copysignl(tiny,x); /*underflow*/
67 k += 54; /* subnormal result */
68 SET_LDOUBLE_EXP(x,(es&0x8000)|k);
69 return x*twom63;
71 weak_alias (__scalbnl, scalbnl)