/* @(#)s_modf.c 1.3 95/01/18 */

/*

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

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

 *

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

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

 * software is freely granted, provided that this notice 

 * is preserved.

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

 */

/*

 * 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"

#ifdef __STDC__

static const double one = 1.0;

#else

static double one = 1.0;

#endif

#ifdef __STDC__

	double modf(double x, double *iptr)

#else

	double modf(x, iptr)

	double x,*iptr;

#endif

{

	int i0,i1,j0;

	unsigned i;

	i0 =  __HI(x);		/* high x */

	i1 =  __LO(x);		/* low  x */

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

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

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

		__HIp(iptr) = i0&0x80000000;

		__LOp(iptr) = 0;		/* *iptr = +-0 */

		return x;

	    } else {

		i = (0x000fffff)>>j0;

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

		    *iptr = x;

		    __HI(x) &= 0x80000000;

		    __LO(x)  = 0;	/* return +-0 */

		    return x;

		} else {

		    __HIp(iptr) = i0&(~i);

		    __LOp(iptr) = 0;

		    return x - *iptr;

		}

	    }

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

	    *iptr = x*one;

	    __HI(x) &= 0x80000000;

	    __LO(x)  = 0;	/* return +-0 */

	    return x;

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

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

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

		*iptr = x;

		__HI(x) &= 0x80000000;

		__LO(x)  = 0;	/* return +-0 */

		return x;

	    } else {

		__HIp(iptr) = i0;

		__LOp(iptr) = i1&(~i);

		return x - *iptr;

	    }

	}

}