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/* Test for NaN that does not need libm.
Copyright (C) 2007-2022 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
#include <config.h>
/* Specification. */
#ifdef USE_LONG_DOUBLE
/* Specification found in math.h or isnanl-nolibm.h. */
extern int rpl_isnanl (long double x) _GL_ATTRIBUTE_CONST;
#elif ! defined USE_FLOAT
/* Specification found in math.h or isnand-nolibm.h. */
extern int rpl_isnand (double x);
#else /* defined USE_FLOAT */
/* Specification found in math.h or isnanf-nolibm.h. */
extern int rpl_isnanf (float x);
#endif
#include <float.h>
#include <string.h>
#include "float+.h"
#ifdef USE_LONG_DOUBLE
# define FUNC rpl_isnanl
# define DOUBLE long double
# define MAX_EXP LDBL_MAX_EXP
# define MIN_EXP LDBL_MIN_EXP
# if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
# define KNOWN_EXPBIT0_LOCATION
# define EXPBIT0_WORD LDBL_EXPBIT0_WORD
# define EXPBIT0_BIT LDBL_EXPBIT0_BIT
# endif
# define SIZE SIZEOF_LDBL
# define L_(literal) literal##L
#elif ! defined USE_FLOAT
# define FUNC rpl_isnand
# define DOUBLE double
# define MAX_EXP DBL_MAX_EXP
# define MIN_EXP DBL_MIN_EXP
# if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
# define KNOWN_EXPBIT0_LOCATION
# define EXPBIT0_WORD DBL_EXPBIT0_WORD
# define EXPBIT0_BIT DBL_EXPBIT0_BIT
# endif
# define SIZE SIZEOF_DBL
# define L_(literal) literal
#else /* defined USE_FLOAT */
# define FUNC rpl_isnanf
# define DOUBLE float
# define MAX_EXP FLT_MAX_EXP
# define MIN_EXP FLT_MIN_EXP
# if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
# define KNOWN_EXPBIT0_LOCATION
# define EXPBIT0_WORD FLT_EXPBIT0_WORD
# define EXPBIT0_BIT FLT_EXPBIT0_BIT
# endif
# define SIZE SIZEOF_FLT
# define L_(literal) literal##f
#endif
#define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
#define NWORDS \
((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
/* Most hosts nowadays use IEEE floating point, so they use IEC 60559
representations, have infinities and NaNs, and do not trap on
exceptions. Define IEEE_FLOATING_POINT if this host is one of the
typical ones. The C11 macro __STDC_IEC_559__ is close to what is
wanted here, but is not quite right because this file does not require
all the features of C11 Annex F (and does not require C11 at all,
for that matter). */
#define IEEE_FLOATING_POINT (FLT_RADIX == 2 && FLT_MANT_DIG == 24 \
&& FLT_MIN_EXP == -125 && FLT_MAX_EXP == 128)
int
FUNC (DOUBLE x)
{
#if defined KNOWN_EXPBIT0_LOCATION && IEEE_FLOATING_POINT
# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
/* Special CPU dependent code is needed to treat bit patterns outside the
IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
These bit patterns are:
- exponent = 0x0001..0x7FFF, mantissa bit 63 = 0,
- exponent = 0x0000, mantissa bit 63 = 1.
The NaN bit pattern is:
- exponent = 0x7FFF, mantissa >= 0x8000000000000001. */
memory_double m;
unsigned int exponent;
m.value = x;
exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
# ifdef WORDS_BIGENDIAN
/* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
if (exponent == 0)
return 1 & (m.word[0] >> 15);
else if (exponent == EXP_MASK)
return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0;
else
return 1 & ~(m.word[0] >> 15);
# else
/* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
if (exponent == 0)
return (m.word[1] >> 31);
else if (exponent == EXP_MASK)
return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
else
return (m.word[1] >> 31) ^ 1;
# endif
# else
/* Be careful to not do any floating-point operation on x, such as x == x,
because x may be a signaling NaN. */
# if defined __SUNPRO_C || defined __ICC || defined _MSC_VER \
|| defined __DECC || defined __TINYC__ \
|| (defined __sgi && !defined __GNUC__)
/* The Sun C 5.0, Intel ICC 10.0, Microsoft Visual C/C++ 9.0, Compaq (ex-DEC)
6.4, and TinyCC compilers don't recognize the initializers as constant
expressions. The Compaq compiler also fails when constant-folding
0.0 / 0.0 even when constant-folding is not required. The Microsoft
Visual C/C++ compiler also fails when constant-folding 1.0 / 0.0 even
when constant-folding is not required. The SGI MIPSpro C compiler
complains about "floating-point operation result is out of range". */
static DOUBLE zero = L_(0.0);
memory_double nan;
DOUBLE plus_inf = L_(1.0) / zero;
DOUBLE minus_inf = -L_(1.0) / zero;
nan.value = zero / zero;
# else
static memory_double nan = { L_(0.0) / L_(0.0) };
static DOUBLE plus_inf = L_(1.0) / L_(0.0);
static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
# endif
{
memory_double m;
/* A NaN can be recognized through its exponent. But exclude +Infinity and
-Infinity, which have the same exponent. */
m.value = x;
if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
& (EXP_MASK << EXPBIT0_BIT))
== 0)
return (memcmp (&m.value, &plus_inf, SIZE) != 0
&& memcmp (&m.value, &minus_inf, SIZE) != 0);
else
return 0;
}
# endif
#else
/* The configuration did not find sufficient information, or does
not use IEEE floating point. Give up about the signaling NaNs;
handle only the quiet NaNs. */
if (x == x)
{
# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
/* Detect any special bit patterns that pass ==; see comment above. */
memory_double m1;
memory_double m2;
memset (&m1.value, 0, SIZE);
memset (&m2.value, 0, SIZE);
m1.value = x;
m2.value = x + (x ? 0.0L : -0.0L);
if (memcmp (&m1.value, &m2.value, SIZE) != 0)
return 1;
# endif
return 0;
}
else
return 1;
#endif
}
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