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 long double __nextafterl(long double x, long double y)
  33 {
  34         u_int32_t hx,hy,ix,iy;
  35         u_int32_t lx,ly;
  36         int32_t esx,esy;
  37
  38         GET_LDOUBLE_WORDS(esx,hx,lx,x);
  39         GET_LDOUBLE_WORDS(esy,hy,ly,y);
  40         ix = esx&0x7fff;                /* |x| */
  41         iy = esy&0x7fff;                /* |y| */
  42
  43         /* Intel's extended format has the normally implicit 1 explicit
  44            present.  Sigh!  */
  45         if(((ix==0x7fff)&&(((hx&0x7fffffff)|lx)!=0)) ||   /* x is nan */
  46            ((iy==0x7fff)&&(((hy&0x7fffffff)|ly)!=0)))     /* y is nan */
  47            return x+y;
  48         if(x==y) return y;              /* x=y, return y */
  49         if((ix|hx|lx)==0) {                     /* x == 0 */
  50             long double u;
  51             SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* 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(esx>=0) {                    /* x > 0 */
  58             if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
  59               /* x > y, x -= ulp */
  60                 if(lx==0) {
  61                     if (hx <= 0x80000000) {
  62                       if (esx == 0) {
  63                         --hx;
  64                       } else {
  65                         esx -= 1;
  66                         hx = hx - 1;
  67                         if (esx > 0)
  68                           hx |= 0x80000000;
  69                       }
  70                     } else
  71                       hx -= 1;
  72                 }
  73                 lx -= 1;
  74             } else {                            /* x < y, x += ulp */
  75                 lx += 1;
  76                 if(lx==0) {
  77                     hx += 1;
  78                     if (hx==0 || (esx == 0 && hx == 0x80000000)) {
  79                         esx += 1;
  80                         hx |= 0x80000000;
  81                     }
  82                 }
  83             }
  84         } else {                                /* x < 0 */
  85             if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
  86               /* x < y, x -= ulp */
  87                 if(lx==0) {
  88                     if (hx <= 0x80000000) {
  89                         esx -= 1;
  90                         hx = hx - 1;
  91                         if ((esx&0x7fff) > 0)
  92                           hx |= 0x80000000;
  93                     } else
  94                       hx -= 1;
  95                 }
  96                 lx -= 1;
  97             } else {                            /* x > y, x += ulp */
  98                 lx += 1;
  99                 if(lx==0) {
 100                     hx += 1;
 101                     if (hx==0 || (esx == 0xffff8000 && hx == 0x80000000)) {
 102                         esx += 1;
 103                         hx |= 0x80000000;
 104                     }
 105                 }
 106             }
 107         }
 108         esy = esx&0x7fff;
 109         if(esy==0x7fff) return x+x;     /* overflow  */
 110         if(esy==0) {
 111             long double u = x*x;                /* underflow */
 112             math_force_eval (u);                /* raise underflow flag */
 113         }
 114         SET_LDOUBLE_WORDS(x,esx,hx,lx);
 115         return x;
 116 }
 117 weak_alias (__nextafterl, nextafterl)
 118 strong_alias (__nextafterl, __nexttowardl)
 119 weak_alias (__nextafterl, nexttowardl)