libm/w_exp2.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 /* wrapper exp2(x) */
  23 double
  24 exp2 (double x)
  25 {
  26 #if defined(__UCLIBC_HAS_FENV__)
  27   double z = pow(2.0, x);
  28   if (__builtin_expect (!isfinite (z) || z == 0, 0)
  29       && isfinite (x) && _LIB_VERSION != _IEEE_)
  30     /* exp2 overflow: 44, exp2 underflow: 45 */
  31     return __kernel_standard (x, x, 44 + !!signbit (x));
  32
  33   return z;
  34 #else
  35   return pow(2.0, x);
  36 #endif
  37 }
  38 libm_hidden_def(exp2)