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 <math.h>
  24 #include <math_private.h>
  25 #include <float.h>
  26
  27 #ifdef __STDC__
  28         float __nexttowardf(float x, long double y)
  29 #else
  30         float __nexttowardf(x,y)
  31         float x;
  32         long double y;
  33 #endif
  34 {
  35         int32_t hx,hy,ix,iy;
  36         u_int32_t ly;
  37
  38         GET_FLOAT_WORD(hx,x);
  39         EXTRACT_WORDS(hy,ly,y);
  40         ix = hx&0x7fffffff;             /* |x| */
  41         iy = hy&0x7fffffff;             /* |y| */
  42
  43         if((ix>0x7f800000) ||                              /* x is nan */
  44            ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))    /* y is nan */
  45            return x+y;
  46         if((long double) x==y) return y;        /* x=y, return y */
  47         if(ix==0) {                             /* x == 0 */
  48             float u;
  49             SET_FLOAT_WORD(x,(u_int32_t)(hy&0x80000000)|1);/* return +-minsub*/
  50             u = math_opt_barrier (x);
  51             u = u * u;
  52             math_force_eval (u);                 /* raise underflow flag */
  53             return x;
  54         }
  55         if(hx>=0) {                             /* x > 0 */
  56             if(hy<0||(ix>>23)>(iy>>20)-0x380
  57                || ((ix>>23)==(iy>>20)-0x380
  58                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x > y, x -= ulp */
  59                 hx -= 1;
  60             else                                /* x < y, x += ulp */
  61                 hx += 1;
  62         } else {                                /* x < 0 */
  63             if(hy>=0||(ix>>23)>(iy>>20)-0x380
  64                || ((ix>>23)==(iy>>20)-0x380
  65                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x < y, x -= ulp */
  66                 hx -= 1;
  67             else                                /* x > y, x += ulp */
  68                 hx += 1;
  69         }
  70         hy = hx&0x7f800000;
  71         if(hy>=0x7f800000) {
  72           x = x+x;      /* overflow  */
  73           if (FLT_EVAL_METHOD != 0)
  74             /* Force conversion to float.  */
  75             asm ("" : "+m"(x));
  76           return x;
  77         }
  78         if(hy<0x00800000) {
  79             float u = x*x;                      /* underflow */
  80             math_force_eval (u);                /* raise underflow flag */
  81         }
  82         SET_FLOAT_WORD(x,hx);
  83         return x;
  84 }
  85 weak_alias (__nexttowardf, nexttowardf)