/*
 * ====================================================
 * 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.
 * ====================================================
 */

/* IEEE functions
 *      nextafter(x,y)
 *      return the next machine floating-point number of x in the
 *      direction toward y.
 *   Special cases:
 */

#include <float.h>

#include "fpmath.h"
#include "math.h"
#include "math_private.h"

#if LDBL_MAX_EXP != 0x4000
#error "Unsupported long double format"
#endif

long double
nextafterl(long double x, long double y)
{
        volatile long double t;
        union IEEEl2bits ux, uy;

        ux.e = x;
        uy.e = y;

        if ((ux.bits.exp == 0x7fff &&
             ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) ||
            (uy.bits.exp == 0x7fff &&
             ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
           return x+y;  /* x or y is nan */
        if(x==y) return y;              /* x=y, return y */
        if(x==0.0) {
            ux.bits.manh = 0;                   /* return +-minsubnormal */
            ux.bits.manl = 1;
            ux.bits.sign = uy.bits.sign;
            t = ux.e*ux.e;
            if(t==ux.e) return t; else return ux.e; /* raise underflow flag */
        }
        if(x>0.0 ^ x<y) {                       /* x -= ulp */
            if(ux.bits.manl==0) {
                if ((ux.bits.manh&~LDBL_NBIT)==0)
                    ux.bits.exp -= 1;
                ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT);
            }
            ux.bits.manl -= 1;
        } else {                                /* x += ulp */
            ux.bits.manl += 1;
            if(ux.bits.manl==0) {
                ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT);
                if ((ux.bits.manh&~LDBL_NBIT)==0)
                    ux.bits.exp += 1;
            }
        }
        if(ux.bits.exp==0x7fff) return x+x;     /* overflow  */
        if(ux.bits.exp==0) {                    /* underflow */
            mask_nbit_l(ux);
            t = ux.e * ux.e;
            if(t!=ux.e)                 /* raise underflow flag */
                return ux.e;
        }
        return ux.e;
}

__strong_reference(nextafterl, nexttowardl);