sysdeps/ieee754/ldbl-128/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
  24 #ifdef __STDC__
  25         float __nexttowardf(float x, long double y)
  26 #else
  27         float __nexttowardf(x,y)
  28         float x;
  29         long double y;
  30 #endif
  31 {
  32         int32_t hx,ix;
  33         int64_t hy,iy;
  34         u_int64_t ly;
  35
  36         GET_FLOAT_WORD(hx,x);
  37         GET_LDOUBLE_WORDS64(hy,ly,y);
  38         ix = hx&0x7fffffff;             /* |x| */
  39         iy = hy&0x7fffffffffffffffLL;   /* |y| */
  40
  41         if((ix>0x7f800000) ||   /* x is nan */
  42            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))
  43                                 /* y is nan */
  44            return x+y;
  45         if((long double) x==y) return y;        /* x=y, return y */
  46         if(ix==0) {                             /* x == 0 */
  47             float x2;
  48             SET_FLOAT_WORD(x,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
  49             x2 = x*x;
  50             if(x2==x) return x2; else return x; /* raise underflow flag */
  51         }
  52         if(hx>=0) {                             /* x > 0 */
  53             if(hy<0||(ix>>23)>(iy>>48)-0x3f80
  54                || ((ix>>23)==(iy>>48)-0x3f80
  55                    && (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x > y, x -= ulp */
  56                 hx -= 1;
  57             } else {                            /* x < y, x += ulp */
  58                 hx += 1;
  59             }
  60         } else {                                /* x < 0 */
  61             if(hy>=0||(ix>>23)>(iy>>48)-0x3f80
  62                || ((ix>>23)==(iy>>48)-0x3f80
  63                    && (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x < y, x -= ulp */
  64                 hx -= 1;
  65             } else {                            /* x > y, x += ulp */
  66                 hx += 1;
  67             }
  68         }
  69         hy = hx&0x7f800000;
  70         if(hy>=0x7f800000) return x+x;  /* overflow  */
  71         if(hy<0x00800000) {             /* underflow */
  72             float x2 = x*x;
  73             if(x2!=x) {         /* raise underflow flag */
  74                 SET_FLOAT_WORD(x2,hx);
  75                 return x2;
  76             }
  77         }
  78         SET_FLOAT_WORD(x,hx);
  79         return x;
  80 }
  81 weak_alias (__nexttowardf, nexttowardf)