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 #ifdef __STDC__
  31         long double __nextafterl(long double x, long double y)
  32 #else
  33         long double __nextafterl(x,y)
  34         long double x,y;
  35 #endif
  36 {
  37         int64_t hx,hy,ix,iy;
  38         u_int64_t lx,ly;
  39
  40         GET_LDOUBLE_WORDS64(hx,lx,x);
  41         GET_LDOUBLE_WORDS64(hy,ly,y);
  42         ix = hx&0x7fffffffffffffffLL;           /* |x| */
  43         iy = hy&0x7fffffffffffffffLL;           /* |y| */
  44
  45         if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
  46            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
  47            return x+y;
  48         if(x==y) return y;              /* x=y, return y */
  49         if((ix|lx)==0) {                        /* x == 0 */
  50             long double u;
  51             SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
  52             u = math_opt_barrier (x);
  53             u = u * u;
  54             math_force_eval (u);                /* raise underflow flag */
  55             return x;
  56         }
  57         if(hx>=0) {                     /* x > 0 */
  58             if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
  59                 if(lx==0) hx--;
  60                 lx--;
  61             } else {                            /* x < y, x += ulp */
  62                 lx++;
  63                 if(lx==0) hx++;
  64             }
  65         } else {                                /* x < 0 */
  66             if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
  67                 if(lx==0) hx--;
  68                 lx--;
  69             } else {                            /* x > y, x += ulp */
  70                 lx++;
  71                 if(lx==0) hx++;
  72             }
  73         }
  74         hy = hx&0x7fff000000000000LL;
  75         if(hy==0x7fff000000000000LL) return x+x;/* overflow  */
  76         if(hy==0) {
  77             long double u = x*x;                /* underflow */
  78             math_force_eval (u);                /* raise underflow flag */
  79         }
  80         SET_LDOUBLE_WORDS64(x,hx,lx);
  81         return x;
  82 }
  83 weak_alias (__nextafterl, nextafterl)
  84 strong_alias (__nextafterl, __nexttowardl)
  85 weak_alias (__nextafterl, nexttowardl)