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             SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
  56             y = x*x;
  57             if(y==x) return y; else return x;   /* raise underflow flag */
  58         }
  59         if(esx>=0) {                    /* x > 0 */
  60             if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
  61               /* x > y, x -= ulp */
  62                 if(lx==0) {
  63                     if (hx <= 0x80000000) {
  64                       if (esx == 0) {
  65                         --hx;
  66                       } else {
  67                         esx -= 1;
  68                         hx = hx - 1;
  69                         if (esx > 0)
  70                           hx |= 0x80000000;
  71                       }
  72                     } else
  73                       hx -= 1;
  74                 }
  75                 lx -= 1;
  76             } else {                            /* x < y, x += ulp */
  77                 lx += 1;
  78                 if(lx==0) {
  79                     hx += 1;
  80                     if (hx==0 || (esx == 0 && hx == 0x80000000)) {
  81                         esx += 1;
  82                         hx |= 0x80000000;
  83                     }
  84                 }
  85             }
  86         } else {                                /* x < 0 */
  87             if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
  88               /* x < y, x -= ulp */
  89                 if(lx==0) {
  90                     if (hx <= 0x80000000) {
  91                         esx -= 1;
  92                         hx = hx - 1;
  93                         if ((esx&0x7fff) > 0)
  94                           hx |= 0x80000000;
  95                     } else
  96                       hx -= 1;
  97                 }
  98                 lx -= 1;
  99             } else {                            /* x > y, x += ulp */
 100                 lx += 1;
 101                 if(lx==0) {
 102                     hx += 1;
 103                     if (hx==0 || (esx == 0xffff8000 && hx == 0x80000000)) {
 104                         esx += 1;
 105                         hx |= 0x80000000;
 106                     }
 107                 }
 108             }
 109         }
 110         esy = esx&0x7fff;
 111         if(esy==0x7fff) return x+x;     /* overflow  */
 112         if(esy==0) {                    /* underflow */
 113             y = x*x;
 114             if(y!=x) {          /* raise underflow flag */
 115                 SET_LDOUBLE_WORDS(y,esx,hx,lx);
 116                 return y;
 117             }
 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)