gen.subproj/isnan.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* @(#)s_isnan.c 5.1 93/09/24 */
  23 /*
  24  * ====================================================
  25  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  26  *
  27  * Developed at SunPro, a Sun Microsystems, Inc. business.
  28  * Permission to use, copy, modify, and distribute this
  29  * software is freely granted, provided that this notice
  30  * is preserved.
  31  * ====================================================
  32  */
  33
  34 #if defined(LIBM_SCCS) && !defined(lint)
  35 static char rcsid[] = "$NetBSD: s_isnan.c,v 1.8 1995/05/10 20:47:36 jtc Exp $";
  36 #endif
  37
  38 /*
  39  * isnan(x) returns 1 is x is nan, else 0;
  40  * no branching!
  41  */
  42
  43 #include <sys/types.h>
  44
  45 typedef union
  46 {
  47   double value;
  48   struct
  49   {
  50 #if defined(__BIG_ENDIAN__)
  51     u_int32_t msw;
  52     u_int32_t lsw;
  53 #else
  54     u_int32_t lsw;
  55     u_int32_t msw;
  56 #endif
  57   } parts;
  58 } ieee_double_shape_type;
  59 /* Get two 32 bit ints from a double.  */
  60
  61 #define EXTRACT_WORDS(ix0,ix1,d)                                \
  62 do {                                                            \
  63   ieee_double_shape_type ew_u;                                  \
  64   ew_u.value = (d);                                             \
  65   (ix0) = ew_u.parts.msw;                                       \
  66   (ix1) = ew_u.parts.lsw;                                       \
  67 } while (0)
  68
  69
  70 #ifdef __STDC__
  71         int isnan(double x)
  72 #else
  73         int isnan(x)
  74         double x;
  75 #endif
  76 {
  77         int32_t hx,lx;
  78         EXTRACT_WORDS(hx,lx,x);
  79         hx &= 0x7fffffff;
  80         hx |= (u_int32_t)(lx|(-lx))>>31;
  81         hx = 0x7ff00000 - hx;
  82         return (int)((u_int32_t)(hx))>>31;
  83 }