sysdeps/libm-ieee754/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 #if defined(LIBM_SCCS) && !defined(lint)
  14 static char rcsid[] = "$NetBSD: s_isnan.c,v 1.8 1995/05/10 20:47:36 jtc Exp $";
  15 #endif
  16
  17 /*
  18  * isnan(x) returns 1 is x is nan, else 0;
  19  * no branching!
  20  */
  21
  22 #include "math.h"
  23 #include "math_private.h"
  24
  25 #ifdef __STDC__
  26         int __isnan(double x)
  27 #else
  28         int __isnan(x)
  29         double x;
  30 #endif
  31 {
  32         int32_t hx,lx;
  33         EXTRACT_WORDS(hx,lx,x);
  34         hx &= 0x7fffffff;
  35         hx |= (u_int32_t)(lx|(-lx))>>31;
  36         hx = 0x7ff00000 - hx;
  37         return (int)((u_int32_t)(hx))>>31;
  38 }
  39 weak_alias (__isnan, isnan)
  40 #ifdef NO_LONG_DOUBLE
  41 weak_alias (__isnan, isnanl)
  42 #endif