1  /* s_nextafterl.c -- long double version of s_nextafter.c.
       2   */
       3  
       4  /*
       5   * ====================================================
       6   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
       7   *
       8   * Developed at SunPro, a Sun Microsystems, Inc. business.
       9   * Permission to use, copy, modify, and distribute this
      10   * software is freely granted, provided that this notice
      11   * is preserved.
      12   * ====================================================
      13   */
      14  
      15  #if defined(LIBM_SCCS) && !defined(lint)
      16  static char rcsid[] = "$NetBSD: $";
      17  #endif
      18  
      19  /* IEEE functions
      20   *	nextafterl(x,y)
      21   *	return the next machine floating-point number of x in the
      22   *	direction toward y.
      23   *   Special cases:
      24   */
      25  
      26  #include <errno.h>
      27  #include <math.h>
      28  #include <math-barriers.h>
      29  #include <math_private.h>
      30  #include <libm-alias-ldouble.h>
      31  
      32  _Float128 __nextafterl(_Float128 x, _Float128 y)
      33  {
      34  	int64_t hx,hy,ix,iy;
      35  	uint64_t lx,ly;
      36  
      37  	GET_LDOUBLE_WORDS64(hx,lx,x);
      38  	GET_LDOUBLE_WORDS64(hy,ly,y);
      39  	ix = hx&0x7fffffffffffffffLL;		/* |x| */
      40  	iy = hy&0x7fffffffffffffffLL;		/* |y| */
      41  
      42  	if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
      43  	   ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
      44  	   return x+y;
      45  	if(x==y) return y;		/* x=y, return y */
      46  	if((ix|lx)==0) {			/* x == 0 */
      47  	    _Float128 u;
      48  	    SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
      49  	    u = math_opt_barrier (x);
      50  	    u = u * u;
      51  	    math_force_eval (u);		/* raise underflow flag */
      52  	    return x;
      53  	}
      54  	if(hx>=0) {			/* x > 0 */
      55  	    if(hx>hy||((hx==hy)&&(lx>ly))) {	/* x > y, x -= ulp */
      56  		if(lx==0) hx--;
      57  		lx--;
      58  	    } else {				/* x < y, x += ulp */
      59  		lx++;
      60  		if(lx==0) hx++;
      61  	    }
      62  	} else {				/* x < 0 */
      63  	    if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
      64  		if(lx==0) hx--;
      65  		lx--;
      66  	    } else {				/* x > y, x += ulp */
      67  		lx++;
      68  		if(lx==0) hx++;
      69  	    }
      70  	}
      71  	hy = hx&0x7fff000000000000LL;
      72  	if(hy==0x7fff000000000000LL) {
      73  	    _Float128 u = x + x;		/* overflow  */
      74  	    math_force_eval (u);
      75  	    __set_errno (ERANGE);
      76  	}
      77  	if(hy==0) {
      78  	    _Float128 u = x*x;		/* underflow */
      79  	    math_force_eval (u);		/* raise underflow flag */
      80  	    __set_errno (ERANGE);
      81  	}
      82  	SET_LDOUBLE_WORDS64(x,hx,lx);
      83  	return x;
      84  }
      85  libm_alias_ldouble (__nextafter, nextafter)
      86  strong_alias (__nextafterl, __nexttowardl)
      87  weak_alias (__nextafterl, nexttowardl)