src/math/scalbf.c

   1 /* origin: FreeBSD /usr/src/lib/msun/src/e_scalbf.c */
   2 /*
   3  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   4  */
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #define _GNU_SOURCE
  17 #include <math.h>
  18
  19 float scalbf(float x, float fn)
  20 {
  21         if (isnan(x) || isnan(fn)) return x*fn;
  22         if (!isfinite(fn)) {
  23                 if (fn > 0.0f)
  24                         return x*fn;
  25                 else
  26                         return x/(-fn);
  27         }
  28         if (rintf(fn) != fn) return (fn-fn)/(fn-fn);
  29         if ( fn > 65000.0f) return scalbnf(x, 65000);
  30         if (-fn > 65000.0f) return scalbnf(x,-65000);
  31         return scalbnf(x,(int)fn);
  32 }