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//===========================================================================

//

//      s_nextafter.c

//

//      Part of the standard mathematical function library

//

//===========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later version.

//

// eCos is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//===========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   jlarmour

// Contributors:  jlarmour

// Date:        1998-02-13

// Purpose:     

// Description: 

// Usage:       

//

//####DESCRIPTIONEND####

//

//===========================================================================

// CONFIGURATION

#include <pkgconf/libm.h>   // Configuration header

// Include the Math library?

#ifdef CYGPKG_LIBM     

// Derived from code with the following copyright

/* @(#)s_nextafter.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.

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

 */

/* IEEE functions

 *      nextafter(x,y)

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

 *      direction toward y.

 *   Special cases:

 */

#include "mathincl/fdlibm.h"

        double nextafter(double x, double y)

{

        int     hx,hy,ix,iy;

        unsigned lx,ly;

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

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

        hy = CYG_LIBM_HI(y);            /* high word of y */

        ly = CYG_LIBM_LO(y);            /* low  word of 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 x;              /* x=y, return x */

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

            CYG_LIBM_HI(x) = hy&0x80000000;     /* return +-minsubnormal */

            CYG_LIBM_LO(x) = 1;

            y = x*x;

            if(y==x) return y; else return x;   /* raise underflow flag */

        }

        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) return x+x;  /* overflow  */

        if(hy<0x00100000) {             /* underflow */

            y = x*x;

            if(y!=x) {          /* raise underflow flag */

                CYG_LIBM_HI(y) = hx; CYG_LIBM_LO(y) = lx;

                return y;

            }

        }

        CYG_LIBM_HI(x) = hx; CYG_LIBM_LO(x) = lx;

        return x;

}

#endif // ifdef CYGPKG_LIBM     

// EOF s_nextafter.c