sysdeps/ieee754/ldbl-128ibm/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  * and Jakub Jelinek, jj@ultra.linux.cz.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 static char rcsid[] = "$NetBSD: $";
  19 #endif
  20
  21 #include <math.h>
  22 #include <math_private.h>
  23 #include <math_ldbl_opt.h>
  24 #include <float.h>
  25
  26 float __nexttowardf(float x, long double y)
  27 {
  28         int32_t hx,ix;
  29         int64_t hy,iy;
  30         double yhi;
  31
  32         GET_FLOAT_WORD(hx,x);
  33         yhi = ldbl_high (y);
  34         EXTRACT_WORDS64 (hy, yhi);
  35         ix = hx&0x7fffffff;             /* |x| */
  36         iy = hy&0x7fffffffffffffffLL;   /* |y| */
  37
  38         if((ix>0x7f800000) ||   /* x is nan */
  39            (iy>0x7ff0000000000000LL))
  40                                 /* y is nan */
  41            return x+y;
  42         if((long double) x==y) return y;        /* x=y, return y */
  43         if(ix==0) {                             /* x == 0 */
  44             float u;
  45             SET_FLOAT_WORD(x,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
  46             u = math_opt_barrier (x);
  47             u = u * u;
  48             math_force_eval (u);                /* raise underflow flag */
  49             return x;
  50         }
  51         if(hx>=0) {                             /* x > 0 */
  52             if(x > y) {                         /* x -= ulp */
  53                 hx -= 1;
  54             } else {                            /* x < y, x += ulp */
  55                 hx += 1;
  56             }
  57         } else {                                /* x < 0 */
  58             if(x < y) {                         /* x -= ulp */
  59                 hx -= 1;
  60             } else {                            /* x > y, x += ulp */
  61                 hx += 1;
  62             }
  63         }
  64         hy = hx&0x7f800000;
  65         if(hy>=0x7f800000) {
  66           x = x+x;      /* overflow  */
  67           if (FLT_EVAL_METHOD != 0)
  68             /* Force conversion to float.  */
  69             asm ("" : "+m"(x));
  70           return x;
  71         }
  72         if(hy<0x00800000) {             /* underflow */
  73             float u = x*x;
  74             math_force_eval (u);        /* raise underflow flag */
  75         }
  76         SET_FLOAT_WORD(x,hx);
  77         return x;
  78 }
  79 long_double_symbol (libm, __nexttowardf, nexttowardf);