/* @(#)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.
 * ====================================================
 */

/* __fdlibm_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 "math.h"

static const double zero = 0.0;

double __fdlibm_remainder(double x, double p) {
	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 = __fdlibm_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;
}