lib/libm/src/s_isnan.c

   1 /* @(#)s_isnan.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 #include <sys/cdefs.h>
  14 #if defined(LIBM_SCCS) && !defined(lint)
  15 __RCSID("$NetBSD: s_isnan.c,v 1.10 1999/07/02 15:37:43 simonb Exp $");
  16 #endif
  17
  18 /*
  19  * isnan(x) returns 1 is x is nan, else 0;
  20  * no branching!
  21  */
  22
  23 #include "math.h"
  24 #include "math_private.h"
  25
  26 int
  27 isnan(double x)
  28 {
  29         int32_t hx,lx;
  30         EXTRACT_WORDS(hx,lx,x);
  31         hx &= 0x7fffffff;
  32         hx |= (u_int32_t)(lx|(-lx))>>31;
  33         hx = 0x7ff00000 - hx;
  34         return (int)((u_int32_t)(hx))>>31;
  35 }