/* @(#)e_remainder.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.

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

 */

/* __ieee754_remainder(x,p)

 * Return :                  

 * 	returns  x REM p  =  x - [x/p]*p as if in infinite 

 * 	precise arithmetic, where [x/p] is the (infinite bit) 

 *	integer nearest x/p (in half way case choose the even one).

 * Method : 

 *	Based on fmod() return x-[x/p]chopped*p exactlp.

 */

#include "fdlibm.h"

#ifdef __STDC__

static const double zero = 0.0;

#else

static double zero = 0.0;

#endif

#ifdef __STDC__

	double __ieee754_remainder(double x, double p)

#else

	double __ieee754_remainder(x,p)

	double x,p;

#endif

{

	int hx,hp;

	unsigned sx,lx,lp;

	double p_half;

	hx = __HI(x);		/* high word of x */

	lx = __LO(x);		/* low  word of x */

	hp = __HI(p);		/* high word of p */

	lp = __LO(p);		/* low  word of p */

	sx = hx&0x80000000;

	hp &= 0x7fffffff;

	hx &= 0x7fffffff;

    /* purge off exception values */

	if((hp|lp)==0) return (x*p)/(x*p); 	/* p = 0 */

	if((hx>=0x7ff00000)||			/* x not finite */

	  ((hp>=0x7ff00000)&&			/* p is NaN */

	  (((hp-0x7ff00000)|lp)!=0)))

	    return (x*p)/(x*p);

	if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p);	/* now x < 2p */

	if (((hx-hp)|(lx-lp))==0) return zero*x;

	x  = fabs(x);

	p  = fabs(p);

	if (hp<0x00200000) {

	    if(x+x>p) {

		x-=p;

		if(x+x>=p) x -= p;

	    }

	} else {

	    p_half = 0.5*p;

	    if(x>p_half) {

		x-=p;

		if(x>=p_half) x -= p;

	    }

	}

	__HI(x) ^= sx;

	return x;

}