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 <errno.h>
  22 #include <math.h>
  23 #include <math-barriers.h>
  24 #include <math_private.h>
  25
  26 float __nexttowardf(float x, _Float128 y)
  27 {
  28         int32_t hx,ix;
  29         int64_t hy,iy;
  30         uint64_t ly;
  31
  32         GET_FLOAT_WORD(hx,x);
  33         GET_LDOUBLE_WORDS64(hy,ly,y);
  34         ix = hx&0x7fffffff;             /* |x| */
  35         iy = hy&0x7fffffffffffffffLL;   /* |y| */
  36
  37         if((ix>0x7f800000) ||   /* x is nan */
  38            ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))
  39                                 /* y is nan */
  40            return x+y;
  41         if((_Float128) x==y) return y;          /* x=y, return y */
  42         if(ix==0) {                             /* x == 0 */
  43             float u;
  44             SET_FLOAT_WORD(x,(uint32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
  45             u = math_opt_barrier (x);
  46             u = u * u;
  47             math_force_eval (u);                /* raise underflow flag */
  48             return x;
  49         }
  50         if(hx>=0) {                             /* x > 0 */
  51             if(x > y) {                         /* x -= ulp */
  52                 hx -= 1;
  53             } else {                            /* x < y, x += ulp */
  54                 hx += 1;
  55             }
  56         } else {                                /* x < 0 */
  57             if(x < y) {                         /* x < y, x -= ulp */
  58                 hx -= 1;
  59             } else {                            /* x > y, x += ulp */
  60                 hx += 1;
  61             }
  62         }
  63         hy = hx&0x7f800000;
  64         if(hy>=0x7f800000) {
  65           float u = x+x;                /* overflow  */
  66           math_force_eval (u);
  67           __set_errno (ERANGE);
  68         }
  69         if(hy<0x00800000) {
  70             float u = x*x;              /* underflow */
  71             math_force_eval (u);        /* raise underflow flag */
  72             __set_errno (ERANGE);
  73         }
  74         SET_FLOAT_WORD(x,hx);
  75         return x;
  76 }
  77 weak_alias (__nexttowardf, nexttowardf)