/* Test for NaN that does not need libm.

   Copyright (C) 2007-2019 Free Software Foundation, Inc.

   This program 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 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 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

}