sysdeps/libm-i387/s_nextafterl.c

   1 /* s_nextafterl.c -- long double version of s_nextafter.c.
   2  * Special version for i387.
   3  * Conversion to long double by Ulrich Drepper,
   4  * Cygnus Support, drepper@cygnus.com.
   5  */
   6
   7 /*
   8  * ====================================================
   9  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  10  *
  11  * Developed at SunPro, a Sun Microsystems, Inc. business.
  12  * Permission to use, copy, modify, and distribute this
  13  * software is freely granted, provided that this notice
  14  * is preserved.
  15  * ====================================================
  16  */
  17
  18 #if defined(LIBM_SCCS) && !defined(lint)
  19 static char rcsid[] = "$NetBSD: $";
  20 #endif
  21
  22 /* IEEE functions
  23  *      nextafterl(x,y)
  24  *      return the next machine floating-point number of x in the
  25  *      direction toward y.
  26  *   Special cases:
  27  */
  28
  29 #include "math.h"
  30 #include "math_private.h"
  31
  32 #ifdef __STDC__
  33         long double __nextafterl(long double x, long double y)
  34 #else
  35         long double __nextafterl(x,y)
  36         long double x,y;
  37 #endif
  38 {
  39         int32_t hx,hy,ix,iy;
  40         u_int32_t lx,ly,esx,esy;
  41
  42         GET_LDOUBLE_WORDS(esx,hx,lx,x);
  43         GET_LDOUBLE_WORDS(esy,hy,ly,y);
  44         ix = esx&0x7fff;                /* |x| */
  45         iy = esy&0x7fff;                /* |y| */
  46
  47         /* The additional &hx/&hy is required because Intel's extended format
  48            has the normally implicit 1 explicit present.  Sigh!  */
  49         if(((ix==0x7fff)&&(((hx|lx)|-(hx|lx))&hx)>>31!=0) ||   /* x is nan */
  50            ((iy==0x7fff)&&(((hy|ly)|-(hy|ly))&hy)>>31!=0))     /* y is nan */
  51            return x+y;
  52         if(x==y) return y;              /* x=y, return y */
  53         if((ix|hx|lx)==0) {                     /* x == 0 */
  54             SET_LDOUBLE_WORDS(x,esx&0x8000,0,1);/* return +-minsubnormal */
  55             y = x*x;
  56             if(y==x) return y; else return x;   /* raise underflow flag */
  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) {                    /* underflow */
  93             y = x*x;
  94             if(y!=x) {          /* raise underflow flag */
  95                 SET_LDOUBLE_WORDS(y,esx,hx,lx);
  96                 return y;
  97             }
  98         }
  99         SET_LDOUBLE_WORDS(x,esx,hx,lx);
 100         return x;
 101 }
 102 weak_alias (__nextafterl, nextafterl)