raze/source/common/thirdparty/math/isnan.c

/*							isnan()
 *							signbit()
 *							isfinite()
 *
 *	Floating point numeric utilities
 *
 *
 *
 * SYNOPSIS:
 *
 * double ceil(), floor(), frexp(), ldexp();
 * int signbit(), isnan(), isfinite();
 * double x, y;
 * int expnt, n;
 *
 * y = floor(x);
 * y = ceil(x);
 * y = frexp( x, &expnt );
 * y = ldexp( x, n );
 * n = signbit(x);
 * n = isnan(x);
 * n = isfinite(x);
 *
 *
 *
 * DESCRIPTION:
 *
 * All four routines return a double precision floating point
 * result.
 *
 * floor() returns the largest integer less than or equal to x.
 * It truncates toward minus infinity.
 *
 * ceil() returns the smallest integer greater than or equal
 * to x.  It truncates toward plus infinity.
 *
 * frexp() extracts the exponent from x.  It returns an integer
 * power of two to expnt and the significand between 0.5 and 1
 * to y.  Thus  x = y * 2**expn.
 *
 * ldexp() multiplies x by 2**n.
 *
 * signbit(x) returns 1 if the sign bit of x is 1, else 0.
 *
 * These functions are part of the standard C run time library
 * for many but not all C compilers.  The ones supplied are
 * written in C for either DEC or IEEE arithmetic.  They should
 * be used only if your compiler library does not already have
 * them.
 *
 * The IEEE versions assume that denormal numbers are implemented
 * in the arithmetic.  Some modifications will be required if
 * the arithmetic has abrupt rather than gradual underflow.
 */


/*
Cephes Math Library Release 2.3:  March, 1995
Copyright 1984, 1995 by Stephen L. Moshier

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. Neither the name of the <ORGANIZATION> nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/


#include "mconf.h"

#ifdef UNK
/* ceil(), floor(), frexp(), ldexp() may need to be rewritten. */
#undef UNK
#if BIGENDIAN
#define MIEEE 1
#else
#define IBMPC 1
#endif
#endif


/* Return 1 if the sign bit of x is 1, else 0.  */

int signbit(double x)
{
union
	{
	double d;
	short s[4];
	int i[2];
	} u;

u.d = x;

if( sizeof(int) == 4 )
	{
#ifdef IBMPC
	return( u.i[1] < 0 );
#endif
#ifdef DEC
	return( u.s[3] < 0 );
#endif
#ifdef MIEEE
	return( u.i[0] < 0 );
#endif
	}
else
	{
#ifdef IBMPC
	return( u.s[3] < 0 );
#endif
#ifdef DEC
	return( u.s[3] < 0 );
#endif
#ifdef MIEEE
	return( u.s[0] < 0 );
#endif
	}
}


/* Return 1 if x is a number that is Not a Number, else return 0.  */

int isnan(double x)
{
#ifdef NANS
union
	{
	double d;
	unsigned short s[4];
	unsigned int i[2];
	} u;

u.d = x;

if( sizeof(int) == 4 )
	{
#ifdef IBMPC
	if( ((u.i[1] & 0x7ff00000) == 0x7ff00000)
	    && (((u.i[1] & 0x000fffff) != 0) || (u.i[0] != 0)))
		return 1;
#endif
#ifdef DEC
	if( (u.s[1] & 0x7fff) == 0)
		{
		if( (u.s[2] | u.s[1] | u.s[0]) != 0 )
			return(1);
		}
#endif
#ifdef MIEEE
	if( ((u.i[0] & 0x7ff00000) == 0x7ff00000)
	    && (((u.i[0] & 0x000fffff) != 0) || (u.i[1] != 0)))
		return 1;
#endif
	return(0);
	}
else
	{ /* size int not 4 */
#ifdef IBMPC
	if( (u.s[3] & 0x7ff0) == 0x7ff0)
		{
		if( ((u.s[3] & 0x000f) | u.s[2] | u.s[1] | u.s[0]) != 0 )
			return(1);
		}
#endif
#ifdef DEC
	if( (u.s[3] & 0x7fff) == 0)
		{
		if( (u.s[2] | u.s[1] | u.s[0]) != 0 )
			return(1);
		}
#endif
#ifdef MIEEE
	if( (u.s[0] & 0x7ff0) == 0x7ff0)
		{
		if( ((u.s[0] & 0x000f) | u.s[1] | u.s[2] | u.s[3]) != 0 )
			return(1);
		}
#endif
	return(0);
	} /* size int not 4 */

#else
/* No NANS.  */
return(0);
#endif
}


/* Return 1 if x is not infinite and is not a NaN.  */

int isfinite(double x)
{
#ifdef INFINITIES
union
	{
	double d;
	unsigned short s[4];
	unsigned int i[2];
	} u;

u.d = x;

if( sizeof(int) == 4 )
	{
#ifdef IBMPC
	if( (u.i[1] & 0x7ff00000) != 0x7ff00000)
		return 1;
#endif
#ifdef DEC
	if( (u.s[3] & 0x7fff) != 0)
		return 1;
#endif
#ifdef MIEEE
	if( (u.i[0] & 0x7ff00000) != 0x7ff00000)
		return 1;
#endif
	return(0);
	}
else
	{
#ifdef IBMPC
	if( (u.s[3] & 0x7ff0) != 0x7ff0)
		return 1;
#endif
#ifdef DEC
	if( (u.s[3] & 0x7fff) != 0)
		return 1;
#endif
#ifdef MIEEE
	if( (u.s[0] & 0x7ff0) != 0x7ff0)
		return 1;
#endif
	return(0);
	}
#else
/* No INFINITY.  */
return(1);
#endif
}