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 <math.h>
  28 #include <math_private.h>
  29
  30 long double __nextafterl(long double x, long double y)
  31 {
  32         int64_t hx,hy,ix,iy;
  33         u_int64_t lx,ly;
  34
  35         GET_LDOUBLE_WORDS64(hx,lx,x);
  36         GET_LDOUBLE_WORDS64(hy,ly,y);
  37         ix = hx&0x7fffffffffffffffLL;           /* |x| */
  38         iy = hy&0x7fffffffffffffffLL;           /* |y| */
  39
  40         if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
  41            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
  42            return x+y;
  43         if(x==y) return y;              /* x=y, return y */
  44         if((ix|lx)==0) {                        /* x == 0 */
  45             long double u;
  46             SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
  47             u = math_opt_barrier (x);
  48             u = u * u;
  49             math_force_eval (u);                /* raise underflow flag */
  50             return x;
  51         }
  52         if(hx>=0) {                     /* x > 0 */
  53             if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
  54                 if(lx==0) hx--;
  55                 lx--;
  56             } else {                            /* x < y, x += ulp */
  57                 lx++;
  58                 if(lx==0) hx++;
  59             }
  60         } else {                                /* x < 0 */
  61             if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
  62                 if(lx==0) hx--;
  63                 lx--;
  64             } else {                            /* x > y, x += ulp */
  65                 lx++;
  66                 if(lx==0) hx++;
  67             }
  68         }
  69         hy = hx&0x7fff000000000000LL;
  70         if(hy==0x7fff000000000000LL) return x+x;/* overflow  */
  71         if(hy==0) {
  72             long double u = x*x;                /* underflow */
  73             math_force_eval (u);                /* raise underflow flag */
  74         }
  75         SET_LDOUBLE_WORDS64(x,hx,lx);
  76         return x;
  77 }
  78 weak_alias (__nextafterl, nextafterl)
  79 strong_alias (__nextafterl, __nexttowardl)
  80 weak_alias (__nextafterl, nexttowardl)