source: trunk/sys/libm/s_finite.c @ 50

/* @(#)s_finite.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice 
 * is preserved.
 * ====================================================
 */

/*
 * finite(x) returns 1 is x is finite, else 0;
 * no branching!
 */

#include <libm/fdlibm.h>

#ifdef __STDC__
static const double one = 1.0;
#else
static double one = 1.0;
#endif

#ifdef __STDC__
        int finite(double x)
#else
        int finite(x)
        double x;
#endif
{
        int n0,hx; 
        n0 = ((*(int*)&one)>>29)^1;
        hx = *(n0+(int*)&x);
        return  (unsigned)((hx&0x7fffffff)-0x7ff00000)>>31;
}