sysdeps/ieee754/ldbl-96/s_nextafterl.c

   1 /* s_nextafterl.c -- long double version of s_nextafter.c.
   2  * Conversion to long double by Ulrich Drepper,
   3  * Cygnus Support, drepper@cygnus.com.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 static char rcsid[] = "$NetBSD: $";
  19 #endif
  20
  21 /* IEEE functions
  22  *      nextafterl(x,y)
  23  *      return the next machine floating-point number of x in the
  24  *      direction toward y.
  25  *   Special cases:
  26  */
  27
  28 #include "math.h"
  29 #include <math_private.h>
  30
  31 #ifdef __STDC__
  32         long double __nextafterl(long double x, long double y)
  33 #else
  34         long double __nextafterl(x,y)
  35         long double x,y;
  36 #endif
  37 {
  38         int32_t hx,hy,ix,iy;
  39         u_int32_t lx,ly,esx,esy;
  40
  41         GET_LDOUBLE_WORDS(esx,hx,lx,x);
  42         GET_LDOUBLE_WORDS(esy,hy,ly,y);
  43         ix = esx&0x7fff;                /* |x| */
  44         iy = esy&0x7fff;                /* |y| */
  45
  46         if (((ix==0x7fff)&&((hx|lx)!=0)) ||   /* x is nan */
  47             ((iy==0x7fff)&&((hy|ly)!=0)))     /* y is nan */
  48            return x+y;
  49         if(x==y) return y;              /* x=y, return y */
  50         if((ix|hx|lx)==0) {                     /* x == 0 */
  51             long double u;
  52             SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
  53             u = math_opt_barrier (x);
  54             u = u * u;
  55             math_force_eval (u);                /* raise underflow flag */
  56             return x;
  57         }
  58         if(esx<0x8000) {                        /* x > 0 */
  59             if(ix>iy||((ix==iy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
  60               /* x > y, x -= ulp */
  61                 if(lx==0) {
  62                     if (hx==0) esx -= 1;
  63                     hx -= 1;
  64                 }
  65                 lx -= 1;
  66             } else {                            /* x < y, x += ulp */
  67                 lx += 1;
  68                 if(lx==0) {
  69                     hx += 1;
  70                     if (hx==0)
  71                         esx += 1;
  72                 }
  73             }
  74         } else {                                /* x < 0 */
  75             if(esy>=0||(ix>iy||((ix==iy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
  76               /* x < y, x -= ulp */
  77                 if(lx==0) {
  78                     if (hx==0) esx -= 1;
  79                     hx -= 1;
  80                 }
  81                 lx -= 1;
  82             } else {                            /* x > y, x += ulp */
  83                 lx += 1;
  84                 if(lx==0) {
  85                     hx += 1;
  86                     if (hx==0) esx += 1;
  87                 }
  88             }
  89         }
  90         esy = esx&0x7fff;
  91         if(esy==0x7fff) return x+x;             /* overflow  */
  92         if(esy==0) {
  93             long double u = x*x;                /* underflow */
  94             math_force_eval (u);                /* raise underflow flag */
  95         }
  96         SET_LDOUBLE_WORDS(x,esx,hx,lx);
  97         return x;
  98 }
  99 weak_alias (__nextafterl, nextafterl)
 100 strong_alias (__nextafterl, __nexttowardl)
 101 weak_alias (__nextafterl, nexttowardl)