xref: /illumos-gate/usr/src/lib/libm/common/C/isnan.c (revision 25c28e83)
1*25c28e83SPiotr Jasiukajtis /*
2*25c28e83SPiotr Jasiukajtis  * CDDL HEADER START
3*25c28e83SPiotr Jasiukajtis  *
4*25c28e83SPiotr Jasiukajtis  * The contents of this file are subject to the terms of the
5*25c28e83SPiotr Jasiukajtis  * Common Development and Distribution License (the "License").
6*25c28e83SPiotr Jasiukajtis  * You may not use this file except in compliance with the License.
7*25c28e83SPiotr Jasiukajtis  *
8*25c28e83SPiotr Jasiukajtis  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*25c28e83SPiotr Jasiukajtis  * or http://www.opensolaris.org/os/licensing.
10*25c28e83SPiotr Jasiukajtis  * See the License for the specific language governing permissions
11*25c28e83SPiotr Jasiukajtis  * and limitations under the License.
12*25c28e83SPiotr Jasiukajtis  *
13*25c28e83SPiotr Jasiukajtis  * When distributing Covered Code, include this CDDL HEADER in each
14*25c28e83SPiotr Jasiukajtis  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*25c28e83SPiotr Jasiukajtis  * If applicable, add the following below this CDDL HEADER, with the
16*25c28e83SPiotr Jasiukajtis  * fields enclosed by brackets "[]" replaced with your own identifying
17*25c28e83SPiotr Jasiukajtis  * information: Portions Copyright [yyyy] [name of copyright owner]
18*25c28e83SPiotr Jasiukajtis  *
19*25c28e83SPiotr Jasiukajtis  * CDDL HEADER END
20*25c28e83SPiotr Jasiukajtis  */
21*25c28e83SPiotr Jasiukajtis /*
22*25c28e83SPiotr Jasiukajtis  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23*25c28e83SPiotr Jasiukajtis  */
24*25c28e83SPiotr Jasiukajtis /*
25*25c28e83SPiotr Jasiukajtis  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
26*25c28e83SPiotr Jasiukajtis  * Use is subject to license terms.
27*25c28e83SPiotr Jasiukajtis  */
28*25c28e83SPiotr Jasiukajtis 
29*25c28e83SPiotr Jasiukajtis #pragma weak isnan = __isnan
30*25c28e83SPiotr Jasiukajtis #pragma weak _isnan = __isnan
31*25c28e83SPiotr Jasiukajtis #pragma weak _isnand = __isnan
32*25c28e83SPiotr Jasiukajtis #pragma weak isnand = __isnan
33*25c28e83SPiotr Jasiukajtis 
34*25c28e83SPiotr Jasiukajtis #include "libm.h"
35*25c28e83SPiotr Jasiukajtis 
36*25c28e83SPiotr Jasiukajtis /*
37*25c28e83SPiotr Jasiukajtis  * The following implementation assumes fast 64-bit integer arith-
38*25c28e83SPiotr Jasiukajtis  * metic.  This is fine for sparc because we build libm in v8plus
39*25c28e83SPiotr Jasiukajtis  * mode.  It's also fine for sparcv9 and amd64.  For x86, it would
40*25c28e83SPiotr Jasiukajtis  * be better to use 32-bit code, but we have assembly for x86.
41*25c28e83SPiotr Jasiukajtis  */
42*25c28e83SPiotr Jasiukajtis int
__isnan(double x)43*25c28e83SPiotr Jasiukajtis __isnan(double x) {
44*25c28e83SPiotr Jasiukajtis 	long long	llx;
45*25c28e83SPiotr Jasiukajtis 
46*25c28e83SPiotr Jasiukajtis 	llx = *(long long *)&x & ~0x8000000000000000ull;
47*25c28e83SPiotr Jasiukajtis 	return ((unsigned long long)(0x7ff0000000000000ll - llx) >> 63);
48*25c28e83SPiotr Jasiukajtis }