1 
2 /* @(#)s_isnan.c 1.3 95/01/18 */
3 /*
4  * ====================================================
5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6  *
7  * Developed at SunSoft, a Sun Microsystems, Inc. business.
8  * Permission to use, copy, modify, and distribute this
9  * software is freely granted, provided that this notice
10  * is preserved.
11  * ====================================================
12  */
13 
14 /*
15  * ieee_isnan(x) returns 1 is x is nan, else 0;
16  * no branching!
17  */
18 
19 #include "fdlibm.h"
20 
21 #ifdef __STDC__
ieee_isnan(double x)22 	int ieee_isnan(double x)
23 #else
24 	int ieee_isnan(x)
25 	double x;
26 #endif
27 {
28 	int hx,lx;
29 	hx = (__HI(x)&0x7fffffff);
30 	lx = __LO(x);
31 	hx |= (unsigned)(lx|(-lx))>>31;
32 	hx = 0x7ff00000 - hx;
33 	return ((unsigned)(hx))>>31;
34 }
35