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57 lines
1.8 KiB
C
57 lines
1.8 KiB
C
/* `NAN' constant for IEEE 754 machines. MIPS version.
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Copyright (C) 1992-2013 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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<http://www.gnu.org/licenses/>. */
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#ifndef _MATH_H
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# error "Never use <bits/nan.h> directly; include <math.h> instead."
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#endif
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/* IEEE Not A Number. */
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/* Note that MIPS has the QNaN and SNaN patterns reversed compared to most
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other architectures. The IEEE spec left the definition of this open to
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implementations, and for MIPS the top bit of the mantissa must be SET to
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indicate a SNaN. */
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#if __GNUC_PREREQ(3,3)
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# define NAN (__builtin_nanf (""))
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#elif defined __GNUC__
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# define NAN \
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(__extension__ \
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((union { unsigned __l __attribute__ ((__mode__ (__SI__))); float __d; }) \
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{ __l: 0x7fbfffffUL }).__d)
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#else
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# include <endian.h>
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# if __BYTE_ORDER == __BIG_ENDIAN
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# define __nan_bytes { 0x7f, 0xbf, 0xff, 0xff }
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# endif
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# if __BYTE_ORDER == __LITTLE_ENDIAN
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# define __nan_bytes { 0xff, 0xff, 0xbf, 0x7f }
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# endif
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static union { unsigned char __c[4]; float __d; } __nan_union
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__attribute__ ((__unused__)) = { __nan_bytes };
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# define NAN (__nan_union.__d)
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#endif /* GCC. */
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