libm/e_scalb.c

   1 /*
   2  * ====================================================
   3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   4  *
   5  * Developed at SunPro, a Sun Microsystems, Inc. business.
   6  * Permission to use, copy, modify, and distribute this
   7  * software is freely granted, provided that this notice
   8  * is preserved.
   9  * ====================================================
  10  */
  11
  12 /*
  13  * __ieee754_scalb(x, fn) is provided for
  14  * passing various standard test suites.
  15  * One should use scalbn() instead.
  16  */
  17
  18 #include "math.h"
  19 #include "math_private.h"
  20 #include <errno.h>
  21
  22 double __ieee754_scalb(double x, double fn)
  23 {
  24         if (isnan(x)||isnan(fn)) return x*fn;
  25         if (!isfinite(fn)) {
  26             if(fn>0.0) return x*fn;
  27             else       return x/(-fn);
  28         }
  29         if (rint(fn)!=fn) return (fn-fn)/(fn-fn);
  30         if ( fn > 65000.0) return scalbn(x, 65000);
  31         if (-fn > 65000.0) return scalbn(x,-65000);
  32         return scalbn(x,(int)fn);
  33 }
  34
  35 #if defined __UCLIBC_SUSV3_LEGACY__
  36 /*
  37  * wrapper scalb(double x, double fn) is provided for
  38  * passing various standard test suites.
  39  * One should use scalbn() instead.
  40  */
  41 #ifndef _IEEE_LIBM
  42 double scalb(double x, double fn)
  43 {
  44         double z = __ieee754_scalb(x, fn);
  45         if (_LIB_VERSION == _IEEE_)
  46                 return z;
  47         if (!(isfinite(z) || isnan(z)) && isfinite(x))
  48                 return __kernel_standard(x, (double)fn, 32); /* scalb overflow */
  49         if (z == 0.0 && z != x)
  50                 return __kernel_standard(x, (double)fn, 33); /* scalb underflow */
  51         if (!isfinite(fn))
  52                 errno = ERANGE;
  53         return z;
  54 }
  55 #else
  56 strong_alias(__ieee754_scalb, scalb)
  57 #endif
  58 libm_hidden_def(scalb)
  59
  60 #endif /* UCLIBC_SUSV3_LEGACY */