/* @(#)s_nextafter.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.

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

 */

#if defined(LIBM_SCCS) && !defined(lint)

static char rcsid[] = "$NetBSD: s_nextafter.c,v 1.8 1995/05/10 20:47:58 jtc Exp $";

#endif

/* IEEE functions

 *	nextafter(x,y)

 *	return the next machine floating-point number of x in the

 *	direction toward y.

 *   Special cases:

 */

/* Ugly hack so that the aliasing works.  */

#define __nexttoward __internal___nexttoward

#define nexttoward __internal_nexttoward

#include <errno.h>

#include <math.h>

#include <math-barriers.h>

#include <math_private.h>

#include <float.h>

#include <libm-alias-double.h>

double __nextafter(double x, double y)

{

	int32_t hx,hy,ix,iy;

	uint32_t lx,ly;

	EXTRACT_WORDS(hx,lx,x);

	EXTRACT_WORDS(hy,ly,y);

	ix = hx&0x7fffffff;		/* |x| */

	iy = hy&0x7fffffff;		/* |y| */

	if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */

	   ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))     /* y is nan */

	   return x+y;

	if(x==y) return y;		/* x=y, return y */

	if((ix|lx)==0) {			/* x == 0 */

	    double u;

	    INSERT_WORDS(x,hy&0x80000000,1);	/* return +-minsubnormal */

	    u = math_opt_barrier (x);

	    u = u*u;

	    math_force_eval (u);		/* raise underflow flag */

	    return x;

	}

	if(hx>=0) {				/* x > 0 */

	    if(hx>hy||((hx==hy)&&(lx>ly))) {	/* x > y, x -= ulp */

		if(lx==0) hx -= 1;

		lx -= 1;

	    } else {				/* x < y, x += ulp */

		lx += 1;

		if(lx==0) hx += 1;

	    }

	} else {				/* x < 0 */

	    if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */

		if(lx==0) hx -= 1;

		lx -= 1;

	    } else {				/* x > y, x += ulp */

		lx += 1;

		if(lx==0) hx += 1;

	    }

	}

	hy = hx&0x7ff00000;

	if(hy>=0x7ff00000) {

	  double u = x+x;	/* overflow  */

	  math_force_eval (u);

	  __set_errno (ERANGE);

	}

	if(hy<0x00100000) {

	    double u = x*x;			/* underflow */

	    math_force_eval (u);		/* raise underflow flag */

	  __set_errno (ERANGE);

	}

	INSERT_WORDS(x,hx,lx);

	return x;

}

libm_alias_double (__nextafter, nextafter)

#ifdef NO_LONG_DOUBLE

strong_alias (__nextafter, __nexttowardl)

weak_alias (__nexttowardl, nexttowardl)

#undef __nexttoward

strong_alias (__nextafter, __nexttoward)

#undef nexttoward

weak_alias (__nextafter, nexttoward)

#endif