w_exp2.c 1.2 KB

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  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. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, see
  14. <http://www.gnu.org/licenses/>. */
  15. #include <math.h>
  16. #include "math_private.h"
  17. /* wrapper exp2(x) */
  18. double
  19. exp2 (double x)
  20. {
  21. #if __UCLIBC_HAS_FENV__
  22. double z = pow(2.0, x);
  23. if (__builtin_expect (!isfinite (z) || z == 0, 0)
  24. && isfinite (x) && _LIB_VERSION != _IEEE_)
  25. /* exp2 overflow: 44, exp2 underflow: 45 */
  26. return __kernel_standard (x, x, 44 + !!signbit (x));
  27. return z;
  28. #else
  29. return pow(2.0, x);
  30. #endif
  31. }
  32. libm_hidden_def(exp2)