ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: purgatorio/libmath/fdlibm/s_isnan.c
/* derived from /netlib/fdlibm */
/* @(#)s_isnan.c 1.3 95/01/18 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* isnan(x) returns 1 is x is nan, else 0;
* no branching!
*/
#include "fdlibm.h"
int isnan(double x)
{
int hx,lx;
hx = (__HI(x)&0x7fffffff);
lx = __LO(x);
hx |= (unsigned)(lx|(-lx))>>31;
hx = 0x7ff00000 - hx;
return ((unsigned)(hx))>>31;
}