math/e_scalb.c

   1 /* @(#)e_scalb.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 #if defined(LIBM_SCCS) && !defined(lint)
  14 static char rcsid[] = "$NetBSD: e_scalb.c,v 1.6 1995/05/10 20:46:09 jtc Exp $";
  15 #endif
  16
  17 /*
  18  * __ieee754_scalb(x, fn) is provide for
  19  * passing various standard test suite. One
  20  * should use scalbn() instead.
  21  */
  22
  23 #include <fenv.h>
  24 #include <math.h>
  25 #include "math_private.h"
  26
  27 #ifdef _SCALB_INT
  28 #ifdef __STDC__
  29         double __ieee754_scalb(double x, int fn)
  30 #else
  31         double __ieee754_scalb(x,fn)
  32         double x; int fn;
  33 #endif
  34 #else
  35 #ifdef __STDC__
  36         double __ieee754_scalb(double x, double fn)
  37 #else
  38         double __ieee754_scalb(x,fn)
  39         double x, fn;
  40 #endif
  41 #endif
  42 {
  43 #ifdef _SCALB_INT
  44         return __scalbn(x,fn);
  45 #else
  46         if (__isnan(x)||__isnan(fn)) return x*fn;
  47         if (!__finite(fn)) {
  48             if(fn>0.0) return x*fn;
  49             else if (x == 0)
  50               return x;
  51             else if (!__finite (x))
  52               {
  53 # ifdef FE_INVALID
  54                 feraiseexcept (FE_INVALID);
  55 # endif
  56                 return __nan ("");
  57               }
  58             else       return x/(-fn);
  59         }
  60         if (__rint(fn)!=fn)
  61           {
  62 # ifdef FE_INVALID
  63             feraiseexcept (FE_INVALID);
  64 # endif
  65             return __nan ("");
  66           }
  67         if ( fn > 65000.0) return __scalbn(x, 65000);
  68         if (-fn > 65000.0) return __scalbn(x,-65000);
  69         return __scalbn(x,(int)fn);
  70 #endif
  71 }