source: trunk/sys/libm/s_isnan.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

First import

File size: 865 bytes
Line 
1
2/* @(#)s_isnan.c 5.1 93/09/24 */
3/*
4 * ====================================================
5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 *
7 * Developed at SunPro, 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 * isnan(x) returns 1 is x is nan, else 0;
16 * no branching!
17 */
18
19#include <libm/fdlibm.h>
20
21#ifdef __STDC__
22static const double one = 1.0;
23#else
24static double one = 1.0;
25#endif
26
27#ifdef __STDC__
28        int isnan(double x)
29#else
30        int isnan(x)
31        double x;
32#endif
33{
34        int n0,hx,lx;
35        n0 = ((*(int*)&one)>>29)^1;
36        hx = (*(n0+(int*)&x)&0x7fffffff);
37        lx = *(1-n0+(int*)&x);
38        hx |= (unsigned)(lx|(-lx))>>31; 
39        hx = 0x7ff00000 - hx;
40        return ((unsigned)(hx))>>31;
41}
Note: See TracBrowser for help on using the repository browser.