sysdeps/ieee754/dbl-64/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 #include <shlib-compat.h>
  25
  26 #undef __isnan
  27 int
  28 __isnan (double x)
  29 {
  30   int32_t hx, lx;
  31   EXTRACT_WORDS (hx, lx, x);
  32   hx &= 0x7fffffff;
  33   hx |= (u_int32_t) (lx | (-lx)) >> 31;
  34   hx = 0x7ff00000 - hx;
  35   return (int) (((u_int32_t) hx) >> 31);
  36 }
  37 hidden_def (__isnan)
  38 weak_alias (__isnan, isnan)
  39 #ifdef NO_LONG_DOUBLE
  40 # if defined LDBL_CLASSIFY_COMPAT && SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_23)
  41 compat_symbol (libc, __isnan, __isnanl, GLIBC_2_0);
  42 # endif
  43 weak_alias (__isnan, isnanl)
  44 #endif