libm/w_scalb.c

   1 /* Copyright (C) 2011-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 #if defined __UCLIBC_SUSV3_LEGACY__
  23
  24 #if defined(__UCLIBC_HAS_FENV__)
  25 #include <errno.h>
  26
  27 static double
  28 __attribute__ ((noinline))
  29 sysv_scalb (double x, double fn)
  30 {
  31   double z = __ieee754_scalb (x, fn);
  32
  33   if (__builtin_expect (isinf (z), 0))
  34     {
  35       if (isfinite (x))
  36         return __kernel_standard (x, fn, 32); /* scalb overflow */
  37       else
  38         __set_errno (ERANGE);
  39     }
  40   else if (__builtin_expect (z == 0.0, 0) && z != x)
  41     return __kernel_standard (x, fn, 33); /* scalb underflow */
  42
  43   return z;
  44 }
  45 #endif /* __UCLIBC_HAS_FENV__ */
  46
  47 /* Wrapper scalb */
  48 double
  49 scalb (double x, double fn)
  50 {
  51 #if defined(__UCLIBC_HAS_FENV__)
  52   if (__builtin_expect (_LIB_VERSION == _SVID_,0))
  53     return sysv_scalb (x, fn);
  54   else
  55     {
  56       double z = __ieee754_scalb (x, fn);
  57
  58       if (__builtin_expect (!isfinite (z) || z == 0.0, 0))
  59         {
  60           if (isnan (z))
  61             {
  62               if (!isnan (x) && !isnan (fn))
  63                 __set_errno (EDOM);
  64             }
  65           else if (isinf (z))
  66             {
  67               if (!isinf (x) && !isinf (fn))
  68                 __set_errno (ERANGE);
  69             }
  70           else
  71             {
  72               /* z == 0.  */
  73               if (x != 0.0 && !isinf (fn))
  74                 __set_errno (ERANGE);
  75             }
  76         }
  77       return z;
  78     }
  79 #else
  80   return __ieee754_scalb (x, fn);
  81 #endif /* __UCLIBC_HAS_FENV__ */
  82 }
  83
  84 libm_hidden_def(scalb)
  85 #endif