1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 
  26 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak isnan = __isnan
  32 #pragma weak _isnan = __isnan
  33 #pragma weak _isnand = __isnan
  34 #pragma weak isnand = __isnan
  35 
  36 #include "libm.h"
  37 
  38 /*
  39  * The following implementation assumes fast 64-bit integer arith-
  40  * metic.  This is fine for sparc because we build libm in v8plus
  41  * mode.  It's also fine for sparcv9 and amd64.  For x86, it would
  42  * be better to use 32-bit code, but we have assembly for x86.
  43  */
  44 int
  45 __isnan(double x)
  46 {
  47         long long llx;
  48 
  49         llx = *(long long *)&x & ~0x8000000000000000ull;
  50         return ((unsigned long long)(0x7ff0000000000000ll - llx) >> 63);
  51 }