sysdeps/ieee754/ldbl-96/s_nexttowardf.c

   1 /* s_nexttowardf.c -- float version of s_nextafter.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: $";
  18 #endif
  19
  20 #include <math.h>
  21 #include <math_private.h>
  22 #include <float.h>
  23
  24 float __nexttowardf(float x, long double y)
  25 {
  26         int32_t hx,ix,iy;
  27         u_int32_t hy,ly,esy;
  28
  29         GET_FLOAT_WORD(hx,x);
  30         GET_LDOUBLE_WORDS(esy,hy,ly,y);
  31         ix = hx&0x7fffffff;             /* |x| */
  32         iy = esy&0x7fff;                /* |y| */
  33
  34         if((ix>0x7f800000) ||                   /* x is nan */
  35            (iy>=0x7fff&&((hy|ly)!=0)))          /* y is nan */
  36            return x+y;
  37         if((long double) x==y) return y;        /* x=y, return y */
  38         if(ix==0) {                             /* x == 0 */
  39             float u;
  40             SET_FLOAT_WORD(x,((esy&0x8000)<<16)|1);/* return +-minsub*/
  41             u = math_opt_barrier (x);
  42             u = u * u;
  43             math_force_eval (u);                /* raise underflow flag */
  44             return x;
  45         }
  46         if(hx>=0) {                             /* x > 0 */
  47             if(x > y) {                         /* x -= ulp */
  48                 hx -= 1;
  49             } else {                            /* x < y, x += ulp */
  50                 hx += 1;
  51             }
  52         } else {                                /* x < 0 */
  53             if(x < y) {                         /* x -= ulp */
  54                 hx -= 1;
  55             } else {                            /* x > y, x += ulp */
  56                 hx += 1;
  57             }
  58         }
  59         hy = hx&0x7f800000;
  60         if(hy>=0x7f800000) {
  61           x = x+x;      /* overflow  */
  62           if (FLT_EVAL_METHOD != 0)
  63             /* Force conversion to float.  */
  64             asm ("" : "+m"(x));
  65           return x;
  66         }
  67         if(hy<0x00800000) {
  68             float u = x*x;                      /* underflow */
  69             math_force_eval (u);                /* raise underflow flag */
  70         }
  71         SET_FLOAT_WORD(x,hx);
  72         return x;
  73 }
  74 weak_alias (__nexttowardf, nexttowardf)