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/* Test for NaN that does not need libm.
Copyright (C) 2007 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
#include <config.h>
#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
#else
# define FUNC rpl_isnan
# 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
#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;
int
FUNC (DOUBLE x)
{
#ifdef KNOWN_EXPBIT0_LOCATION
/* 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 __DECC
/* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
recognize the initializers as constant expressions. The latter compiler
also fails when constant-folding 0.0 / 0.0 even when constant-folding is
not required. */
static DOUBLE zero = L_(0.0);
memory_double nan;
DOUBLE plus_inf = L_(1.0) / L_(0.0);
DOUBLE minus_inf = -L_(1.0) / L_(0.0);
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;
}
#else
/* The configuration did not find sufficient information. Give up about
the signaling NaNs, handle only the quiet NaNs. */
if (x == x)
return 0;
else
return 1;
#endif
}
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