sysdeps/ieee754/ldbl-128/s_nextafterl.c

   1 /* s_nextafterl.c -- long double version of s_nextafter.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: $";
  18 #endif
  19
  20 /* IEEE functions
  21  *      nextafterl(x,y)
  22  *      return the next machine floating-point number of x in the
  23  *      direction toward y.
  24  *   Special cases:
  25  */
  26
  27 #include <errno.h>
  28 #include <math.h>
  29 #include <math_private.h>
  30
  31 _Float128 __nextafterl(_Float128 x, _Float128 y)
  32 {
  33         int64_t hx,hy,ix,iy;
  34         u_int64_t lx,ly;
  35
  36         GET_LDOUBLE_WORDS64(hx,lx,x);
  37         GET_LDOUBLE_WORDS64(hy,ly,y);
  38         ix = hx&0x7fffffffffffffffLL;           /* |x| */
  39         iy = hy&0x7fffffffffffffffLL;           /* |y| */
  40
  41         if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
  42            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
  43            return x+y;
  44         if(x==y) return y;              /* x=y, return y */
  45         if((ix|lx)==0) {                        /* x == 0 */
  46             _Float128 u;
  47             SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
  48             u = math_opt_barrier (x);
  49             u = u * u;
  50             math_force_eval (u);                /* raise underflow flag */
  51             return x;
  52         }
  53         if(hx>=0) {                     /* x > 0 */
  54             if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
  55                 if(lx==0) hx--;
  56                 lx--;
  57             } else {                            /* x < y, x += ulp */
  58                 lx++;
  59                 if(lx==0) hx++;
  60             }
  61         } else {                                /* x < 0 */
  62             if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
  63                 if(lx==0) hx--;
  64                 lx--;
  65             } else {                            /* x > y, x += ulp */
  66                 lx++;
  67                 if(lx==0) hx++;
  68             }
  69         }
  70         hy = hx&0x7fff000000000000LL;
  71         if(hy==0x7fff000000000000LL) {
  72             _Float128 u = x + x;                /* overflow  */
  73             math_force_eval (u);
  74             __set_errno (ERANGE);
  75         }
  76         if(hy==0) {
  77             _Float128 u = x*x;          /* underflow */
  78             math_force_eval (u);                /* raise underflow flag */
  79             __set_errno (ERANGE);
  80         }
  81         SET_LDOUBLE_WORDS64(x,hx,lx);
  82         return x;
  83 }
  84 weak_alias (__nextafterl, nextafterl)
  85 strong_alias (__nextafterl, __nexttowardl)
  86 weak_alias (__nextafterl, nexttowardl)