xref: /freebsd/lib/msun/src/e_scalb.c (revision 7a773faadc6bc6853fd1ecd70099591247656e39)
1 /* @(#)e_scalb.c 5.1 93/09/24 */
2 /*
3  * ====================================================
4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5  *
6  * Developed at SunPro, a Sun Microsystems, Inc. business.
7  * Permission to use, copy, modify, and distribute this
8  * software is freely granted, provided that this notice
9  * is preserved.
10  * ====================================================
11  */
12 
13 #ifndef lint
14 static char rcsid[] = "$FreeBSD$";
15 #endif
16 
17 /*
18  * __ieee754_scalb(x, fn) is provide for
19  * passing various standard test suite. One
20  * should use scalbn() instead.
21  */
22 
23 #include "math.h"
24 #include "math_private.h"
25 
26 /* XXX lost declaration of this and isinf() in math.h but still have funcs. */
27 int	(isnan)(float x);
28 
29 #ifdef _SCALB_INT
30 double
31 __ieee754_scalb(double x, int fn)
32 #else
33 double
34 __ieee754_scalb(double x, double fn)
35 #endif
36 {
37 #ifdef _SCALB_INT
38 	return scalbn(x,fn);
39 #else
40 	if ((isnan)(x)||(isnan)(fn)) return x*fn;
41 	if (!finite(fn)) {
42 	    if(fn>0.0) return x*fn;
43 	    else       return x/(-fn);
44 	}
45 	if (rint(fn)!=fn) return (fn-fn)/(fn-fn);
46 	if ( fn > 65000.0) return scalbn(x, 65000);
47 	if (-fn > 65000.0) return scalbn(x,-65000);
48 	return scalbn(x,(int)fn);
49 #endif
50 }
51