sysdeps/i386/fpu/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         u_int32_t hx,hy,ix,iy;
  40         u_int32_t lx,ly;
  41         int32_t esx,esy;
  42
  43         GET_LDOUBLE_WORDS(esx,hx,lx,x);
  44         GET_LDOUBLE_WORDS(esy,hy,ly,y);
  45         ix = esx&0x7fff;                /* |x| */
  46         iy = esy&0x7fff;                /* |y| */
  47
  48         /* Intel's extended format has the normally implicit 1 explicit
  49            present.  Sigh!  */
  50         if(((ix==0x7fff)&&(((hx&0x7fffffff)|lx)!=0)) ||   /* x is nan */
  51            ((iy==0x7fff)&&(((hy&0x7fffffff)|ly)!=0)))     /* y is nan */
  52            return x+y;
  53         if(x==y) return y;              /* x=y, return y */
  54         if((ix|hx|lx)==0) {                     /* x == 0 */
  55             long double u;
  56             SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
  57             u = math_opt_barrier (x);
  58             u = u * u;
  59             math_force_eval (u);                /* raise underflow flag */
  60             return x;
  61         }
  62         if(esx>=0) {                    /* x > 0 */
  63             if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
  64               /* x > y, x -= ulp */
  65                 if(lx==0) {
  66                     if (hx <= 0x80000000) {
  67                       if (esx == 0) {
  68                         --hx;
  69                       } else {
  70                         esx -= 1;
  71                         hx = hx - 1;
  72                         if (esx > 0)
  73                           hx |= 0x80000000;
  74                       }
  75                     } else
  76                       hx -= 1;
  77                 }
  78                 lx -= 1;
  79             } else {                            /* x < y, x += ulp */
  80                 lx += 1;
  81                 if(lx==0) {
  82                     hx += 1;
  83                     if (hx==0 || (esx == 0 && hx == 0x80000000)) {
  84                         esx += 1;
  85                         hx |= 0x80000000;
  86                     }
  87                 }
  88             }
  89         } else {                                /* x < 0 */
  90             if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
  91               /* x < y, x -= ulp */
  92                 if(lx==0) {
  93                     if (hx <= 0x80000000) {
  94                         esx -= 1;
  95                         hx = hx - 1;
  96                         if ((esx&0x7fff) > 0)
  97                           hx |= 0x80000000;
  98                     } else
  99                       hx -= 1;
 100                 }
 101                 lx -= 1;
 102             } else {                            /* x > y, x += ulp */
 103                 lx += 1;
 104                 if(lx==0) {
 105                     hx += 1;
 106                     if (hx==0 || (esx == 0xffff8000 && hx == 0x80000000)) {
 107                         esx += 1;
 108                         hx |= 0x80000000;
 109                     }
 110                 }
 111             }
 112         }
 113         esy = esx&0x7fff;
 114         if(esy==0x7fff) return x+x;     /* overflow  */
 115         if(esy==0) {
 116             long double u = x*x;                /* underflow */
 117             math_force_eval (u);                /* raise underflow flag */
 118         }
 119         SET_LDOUBLE_WORDS(x,esx,hx,lx);
 120         return x;
 121 }
 122 weak_alias (__nextafterl, nextafterl)
 123 strong_alias (__nextafterl, __nexttowardl)
 124 weak_alias (__nextafterl, nexttowardl)