1 /* Test for signaling NaN.
2 Copyright (C) 2013-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
20 #include <math_private.h>
21 #include <nan-high-order-bit.h>
24 __issignaling (double x
)
26 #if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
28 GET_HIGH_WORD (hxi
, x
);
29 /* We only have to care about the high-order bit of x's significand, because
30 having it set (sNaN) already makes the significand different from that
31 used to designate infinity. */
32 return (hxi
& 0x7ff80000) == 0x7ff80000;
35 EXTRACT_WORDS (hxi
, lxi
, x
);
36 /* To keep the following comparison simple, toggle the quiet/signaling bit,
37 so that it is set for sNaNs. This is inverse to IEEE 754-2008 (as well as
38 common practice for IEEE 754-1985). */
40 /* If lxi != 0, then set any suitable bit of the significand in hxi. */
41 hxi
|= (lxi
| -lxi
) >> 31;
42 /* We have to compare for greater (instead of greater or equal), because x's
43 significand being all-zero designates infinity not NaN. */
44 return (hxi
& 0x7fffffff) > 0x7ff80000;
47 libm_hidden_def (__issignaling
)