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/* @(#)z_isnan.c 1.0 98/08/13 */

/*

FUNCTION

        <<isnan>>,<<isnanf>>,<<isinf>>,<<isinff>>,<<finite>>,<<finitef>>---test

for exceptional numbers

INDEX

        isnan

INDEX

        isinf

INDEX

        finite

INDEX

        isnanf

INDEX

        isinff

INDEX

        finitef

ANSI_SYNOPSIS

        #include <ieeefp.h>

        int isnan(double <[arg]>);

        int isinf(double <[arg]>);

        int finite(double <[arg]>);

        int isnanf(float <[arg]>);

        int isinff(float <[arg]>);

        int finitef(float <[arg]>);

TRAD_SYNOPSIS

        #include <ieeefp.h>

        int isnan(<[arg]>)

        double <[arg]>;

        int isinf(<[arg]>)

        double <[arg]>;

        int finite(<[arg]>);

        double <[arg]>;

        int isnanf(<[arg]>);

        float <[arg]>;

        int isinff(<[arg]>);

        float <[arg]>;

        int finitef(<[arg]>);

        float <[arg]>;

DESCRIPTION

        These functions provide information on the floating point

        argument supplied.

        There are five major number formats -

        o+

        o zero

         a number which contains all zero bits.

        o subnormal

         Is used to represent  number with a zero exponent, but a non zero fract

ion.

         o normal

          A number with an exponent, and a fraction

        o infinity

          A number with an all 1's exponent and a zero fraction.

        o NAN

          A number with an all 1's exponent and a non zero fraction.

        o-

        <<isnan>> returns 1 if the argument is a nan. <<isinf>>

        returns 1 if the argument is infinity.  <<finite>> returns 1 if the

        argument is zero, subnormal or normal.

        The <<isnanf>>, <<isinff>> and <<finitef>> perform the same

        operations as their <<isnan>>, <<isinf>> and <<finite>>

        counterparts, but on single precision floating point numbers.

QUICKREF

        isnan - pure

QUICKREF

        isinf - pure

QUICKREF

        finite - pure

QUICKREF

        isnan - pure

QUICKREF

        isinf - pure

QUICKREF

        finite - pure

*/

/******************************************************************

 * isnan

 *

 * Input:

 *   x - pointer to a floating point value

 *

 * Output:

 *   An integer that indicates if the number is NaN.

 *

 * Description:

 *   This routine returns an integer that indicates if the number

 *   passed in is NaN (1) or is finite (0).

 *

 *****************************************************************/

#include "fdlibm.h"

#include "zmath.h"

#ifndef _DOUBLE_IS_32BITS

int isnan (double x)

{

  __uint32_t lx, hx;

  int exp;

  EXTRACT_WORDS (hx, lx, x);

  exp = (hx & 0x7ff00000) >> 20;

  if ((exp == 0x7ff) && (hx & 0xf0000 || lx))

    return (1);

  else

    return (0);

}

#endif /* _DOUBLE_IS_32BITS */