sysdeps/generic/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
  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,hy,ix,iy;
  35         u_int32_t ly;
  36
  37         GET_FLOAT_WORD(hx,x);
  38         EXTRACT_WORDS(hy,ly,y);
  39         ix = hx&0x7fffffff;             /* |x| */
  40         iy = hy&0x7fffffff;             /* |y| */
  41
  42         if((ix>0x7f800000) ||                              /* x is nan */
  43            ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))    /* 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&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>>20)-0x380
  54                || ((ix>>23)==(iy>>20)-0x380
  55                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x > y, x -= ulp */
  56                 hx -= 1;
  57             else                                /* x < y, x += ulp */
  58                 hx += 1;
  59         } else {                                /* x < 0 */
  60             if(hy>=0||(ix>>23)>(iy>>20)-0x380
  61                || ((ix>>23)==(iy>>20)-0x380
  62                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x < y, x -= ulp */
  63                 hx -= 1;
  64             else                                /* x > y, x += ulp */
  65                 hx += 1;
  66         }
  67         hy = hx&0x7f800000;
  68         if(hy>=0x7f800000) return x+x;  /* overflow  */
  69         if(hy<0x00800000) {             /* underflow */
  70             float x2 = x*x;
  71             if(x2!=x) {         /* raise underflow flag */
  72                 SET_FLOAT_WORD(x2,hx);
  73                 return x2;
  74             }
  75         }
  76         SET_FLOAT_WORD(x,hx);
  77         return x;
  78 }
  79 weak_alias (__nexttowardf, nexttowardf)