math/s_nexttowardf.c

   1 /* Single precision version of nexttoward.c.
   2    Conversion to IEEE single float by Jakub Jelinek, jj@ultra.linux.cz. */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /* IEEE functions
  15  *      nexttowardf(x,y)
  16  *      return the next machine floating-point number of x in the
  17  *      direction toward y.
  18  * This is for machines which use the same binary type for double and
  19  * long double.
  20  *   Special cases:
  21  */
  22
  23 #include <errno.h>
  24 #include <math.h>
  25 #include <math_private.h>
  26 #include <float.h>
  27
  28 float __nexttowardf(float x, long double y)
  29 {
  30         int32_t hx,hy,ix,iy;
  31         u_int32_t ly;
  32
  33         GET_FLOAT_WORD(hx,x);
  34         EXTRACT_WORDS(hy,ly,y);
  35         ix = hx&0x7fffffff;             /* |x| */
  36         iy = hy&0x7fffffff;             /* |y| */
  37
  38         if((ix>0x7f800000) ||                              /* x is nan */
  39            ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))    /* y is nan */
  40            return x+y;
  41         if((long double) x==y) return y;        /* x=y, return y */
  42         if(ix==0) {                             /* x == 0 */
  43             float u;
  44             SET_FLOAT_WORD(x,(u_int32_t)(hy&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         } else {                                /* x < 0 */
  56             if(x < y)                           /* x -= ulp */
  57                 hx -= 1;
  58             else                                /* x > y, x += ulp */
  59                 hx += 1;
  60         }
  61         hy = hx&0x7f800000;
  62         if(hy>=0x7f800000) {
  63           float u = x+x;                        /* overflow  */
  64           math_force_eval (u);
  65           __set_errno (ERANGE);
  66         }
  67         if(hy<0x00800000) {
  68             float u = x*x;                      /* underflow */
  69             math_force_eval (u);                /* raise underflow flag */
  70             __set_errno (ERANGE);
  71         }
  72         SET_FLOAT_WORD(x,hx);
  73         return x;
  74 }
  75 weak_alias (__nexttowardf, nexttowardf)