/* s_nexttoward.c

 * Special i387 version

 * Conversion from s_nextafter.c by Ulrich Drepper, Cygnus Support,

 * drepper@cygnus.com.

 */

/*

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

 * 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: $";

#endif

/* IEEE functions

 *	nexttoward(x,y)

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

 *	direction toward y.

 *   Special cases:

 */

#include <errno.h>

#include <math.h>

#include <math-barriers.h>

#include <math_private.h>

#include <float.h>

double __nexttoward(double x, long double y)

{

	int32_t hx,ix,iy;

	uint32_t lx,hy,ly,esy;

	EXTRACT_WORDS(hx,lx,x);

	GET_LDOUBLE_WORDS(esy,hy,ly,y);

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

	iy = esy&0x7fff;		/* |y| */

	/* Intel's extended format has the normally implicit 1 explicit

	   present.  Sigh!  */

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

	   ((iy>=0x7fff)&&((hy&0x7fffffff)|ly)!=0))        /* y is nan */

	   return x+y;

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

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

	    double u;

	    INSERT_WORDS(x,(esy&0x8000)<<16,1); /* return +-minsub */

	    u = math_opt_barrier (x);

	    u = u * u;

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

	    return x;

	}

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

	    if (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 (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;

}

weak_alias (__nexttoward, nexttoward)

#ifdef NO_LONG_DOUBLE

strong_alias (__nexttoward, __nexttowardl)

weak_alias (__nexttoward, nexttowardl)

#endif