1 /* Test for signaling NaN.
2 Copyright (C) 2013-2014 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>
23 __issignalingl (long double x
)
26 /* For inspecting NaN status, we only have to look at the first of the pair
27 of IEEE 754 64-bit precision numbers. */
31 EXTRACT_WORDS64 (xi
, xhi
);
32 #ifdef HIGH_ORDER_BIT_IS_SET_FOR_SNAN
34 /* We only have to care about the high-order bit of x's significand, because
35 having it set (sNaN) already makes the significand different from that
36 used to designate infinity. */
37 return (xi
& UINT64_C (0x7ff8000000000000)) == UINT64_C (0x7ff8000000000000);
39 /* To keep the following comparison simple, toggle the quiet/signaling bit,
40 so that it is set for sNaNs. This is inverse to IEEE 754-2008 (as well as
41 common practice for IEEE 754-1985). */
42 xi
^= UINT64_C (0x0008000000000000);
43 /* We have to compare for greater (instead of greater or equal), because x's
44 significand being all-zero designates infinity not NaN. */
45 return (xi
& UINT64_C (0x7fffffffffffffff)) > UINT64_C (0x7ff8000000000000);
48 libm_hidden_def (__issignalingl
)