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44 lines
1.7 KiB
C
44 lines
1.7 KiB
C
/* Test for signaling NaN.
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Copyright (C) 2013-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_private.h>
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#include <nan-high-order-bit.h>
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int
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__issignaling (double x)
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{
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uint64_t xi;
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EXTRACT_WORDS64 (xi, x);
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#if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
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/* We only have to care about the high-order bit of x's significand, because
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having it set (sNaN) already makes the significand different from that
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used to designate infinity. */
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return (xi & UINT64_C (0x7ff8000000000000)) == UINT64_C (0x7ff8000000000000);
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#else
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/* To keep the following comparison simple, toggle the quiet/signaling bit,
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so that it is set for sNaNs. This is inverse to IEEE 754-2008 (as well as
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common practice for IEEE 754-1985). */
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xi ^= UINT64_C (0x0008000000000000);
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/* We have to compare for greater (instead of greater or equal), because x's
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significand being all-zero designates infinity not NaN. */
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return (xi & UINT64_C (0x7fffffffffffffff)) > UINT64_C (0x7ff8000000000000);
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#endif
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}
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libm_hidden_def (__issignaling)
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