/* S_MODF.C

 * 

 * Portions Copyright (c) 1993-1999 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 */

/* @(#)s_modf.c 5.1 93/09/24 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice 

 * is preserved.

 * ====================================================

 */

/*

FUNCTION

       <<modf>>, <<modff>>---split fractional and integer parts

INDEX

	modf

INDEX

	modff

ANSI_SYNOPSIS

	#include <math.h>

	double modf(double <[val]>, double *<[ipart]>);

        float modff(float <[val]>, float *<[ipart]>);

TRAD_SYNOPSIS

	#include <math.h>

	double modf(<[val]>, <[ipart]>)

        double <[val]>;

        double *<[ipart]>;

	float modff(<[val]>, <[ipart]>)

	float <[val]>;

        float *<[ipart]>;

DESCRIPTION

	<<modf>> splits the double <[val]> apart into an integer part

	and a fractional part, returning the fractional part and

	storing the integer part in <<*<[ipart]>>>.  No rounding

	whatsoever is done; the sum of the integer and fractional

	parts is guaranteed to be exactly  equal to <[val]>.   That

	is, if . <[realpart]> = modf(<[val]>, &<[intpart]>); then

	`<<<[realpart]>+<[intpart]>>>' is the same as <[val]>.

	<<modff>> is identical, save that it takes and returns

	<<float>> rather than <<double>> values. 

RETURNS

	The fractional part is returned.  Each result has the same

	sign as the supplied argument <[val]>.

PORTABILITY

	<<modf>> is ANSI C. <<modff>> is an extension.

QUICKREF

	modf  ansi pure 

	modff - pure

*/

/*

 * modf(double x, double *iptr) 

 * return fraction part of x, and return x's integral part in *iptr.

 * Method:

 *	Bit twiddling.

 *

 * Exception:

 *	No exception.

 */

#include "FDLIBM.H"

static const double one = 1.0;

/**

Split floating-point value into fractional and integer parts.

Breaks x in two parts: the integer (stored in location pointed by iptr)

and the fraction (return value).

@return Fractional part of x

@param x Floating point value. 

@param iptr Location where the integer part of x will be stored.

*/	

EXPORT_C double modf(double x, double *iptr) __SOFTFP

{

	__int32_t i0,i1,j0;

	__uint32_t i;

	EXTRACT_WORDS(i0,i1,x);

	j0 = ((i0>>20)&0x7ff)-0x3ff;	/* exponent of x */

	if(j0<20) {			/* integer part in high x */

	    if(j0<0) {			/* |x|<1 */

	        INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */

		return x;

	    } else {

		i = (0x000fffff)>>j0;

		if(((i0&i)|i1)==0) {		/* x is integral */

		    __uint32_t high;

		    *iptr = x;

		    GET_HIGH_WORD(high,x);

		    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */

		    return x;

		} else {

		    INSERT_WORDS(*iptr,i0&(~i),0);

		    return x - *iptr;

		}

	    }

	} else if (j0>51) {		/* no fraction part */

	    __uint32_t high;

	    *iptr = x*one;

	    GET_HIGH_WORD(high,x);

	    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */

	    return x;

	} else {			/* fraction part in low x */

	    i = ((__uint32_t)(0xffffffff))>>(j0-20);

	    if((i1&i)==0) { 		/* x is integral */

	        __uint32_t high;

		*iptr = x;

		GET_HIGH_WORD(high,x);

		INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */

		return x;

	    } else {

	        INSERT_WORDS(*iptr,i0,i1&(~i));

		return x - *iptr;

	    }

	}

}