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 */
5
6/*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
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 * ====================================================
15 */
16
17#if defined(LIBM_SCCS) && !defined(lint)
18static char rcsid[] = "$NetBSD: $";
19#endif
20
21/*
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.
26 */
27
28#include "math.h"
29#include "math_private.h"
30
31#ifdef __STDC__
32static const long double
33#else
34static long double
35#endif
36two63   =  4.50359962737049600000e+15,
37twom63  =  1.08420217248550443400e-19,
38huge   = 1.0e+4900L,
39tiny   = 1.0e-4900L;
40
41#ifdef __STDC__
42	long double __scalblnl (long double x, long int n)
43#else
44	long double __scalblnl (x,n)
45	long double x; long int n;
46#endif
47{
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;
56	    }
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 += 63;				/* subnormal result */
68	SET_LDOUBLE_EXP(x,(es&0x8000)|k);
69        return x*twom63;
70}
71weak_alias (__scalblnl, scalblnl)
72