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 #ifdef __STDC__
  27         float __nexttowardf(float x, long double y)
  28 #else
  29         float __nexttowardf(x,y)
  30         float x;
  31         long double y;
  32 #endif
  33 {
  34         int32_t hx,ix;
  35         int64_t hy,iy;
  36         u_int64_t ly, uly;
  37
  38         GET_FLOAT_WORD(hx,x);
  39         GET_LDOUBLE_WORDS64(hy,ly,y);
  40         ix = hx&0x7fffffff;             /* |x| */
  41         iy = hy&0x7fffffffffffffffLL;   /* |y| */
  42         uly = ly&0x7fffffffffffffffLL;  /* |y| */
  43
  44         if((ix>0x7f800000) ||   /* x is nan */
  45            ((iy>=0x7ff0000000000000LL)&&((iy-0x7ff0000000000000LL)|uly)!=0))
  46                                 /* y is nan */
  47            return x+y;
  48         if((long double) x==y) return y;        /* x=y, return y */
  49         if(ix==0) {                             /* x == 0 */
  50             float u;
  51             SET_FLOAT_WORD(x,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
  52             u = math_opt_barrier (x);
  53             u = u * u;
  54             math_force_eval (u);                /* raise underflow flag */
  55             return x;
  56         }
  57         if(hx>=0) {                             /* x > 0 */
  58             if(hy<0||(ix>>23)>(iy>>52)-0x380
  59                || ((ix>>23)==(iy>>52)-0x380
  60                    && (ix&0x7fffff)>((hy>>29)&0x7fffff))) {/* x > y, x -= ulp */
  61                 hx -= 1;
  62             } else {                            /* x < y, x += ulp */
  63                 hx += 1;
  64             }
  65         } else {                                /* x < 0 */
  66             if(hy>=0||(ix>>23)>(iy>>52)-0x380
  67                || ((ix>>23)==(iy>>52)-0x380
  68                    && (ix&0x7fffff)>((hy>>29)&0x7fffff))) {/* x < y, x -= ulp */
  69                 hx -= 1;
  70             } else {                            /* x > y, x += ulp */
  71                 hx += 1;
  72             }
  73         }
  74         hy = hx&0x7f800000;
  75         if(hy>=0x7f800000) {
  76           x = x+x;      /* overflow  */
  77           if (FLT_EVAL_METHOD != 0)
  78             /* Force conversion to float.  */
  79             asm ("" : "+m"(x));
  80           return x;
  81         }
  82         if(hy<0x00800000) {             /* underflow */
  83             float u = x*x;
  84             math_force_eval (u);        /* raise underflow flag */
  85         }
  86         SET_FLOAT_WORD(x,hx);
  87         return x;
  88 }
  89 long_double_symbol (libm, __nexttowardf, nexttowardf);