w_powf.c 2.1 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 powf */
  18. float
  19. powf (float x, float y)
  20. {
  21. #if __UCLIBC_HAS_FENV__
  22. float z = (float) __ieee754_pow ((double) x, (double) y);
  23. if (__builtin_expect (!isfinite (z), 0))
  24. {
  25. if (_LIB_VERSION != _IEEE_)
  26. {
  27. if (isnan (x))
  28. {
  29. if (y == 0.0f)
  30. /* pow(NaN,0.0) */
  31. return __kernel_standard_f (x, y, 142);
  32. }
  33. else if (isfinite (x) && isfinite (y))
  34. {
  35. if (isnan (z))
  36. /* pow neg**non-int */
  37. return __kernel_standard_f (x, y, 124);
  38. else if (x == 0.0f && y < 0.0f)
  39. {
  40. if (signbit (x) && signbit (z))
  41. /* pow(-0.0,negative) */
  42. return __kernel_standard_f (x, y, 123);
  43. else
  44. /* pow(+0.0,negative) */
  45. return __kernel_standard_f (x, y, 143);
  46. }
  47. else
  48. /* pow overflow */
  49. return __kernel_standard_f (x, y, 121);
  50. }
  51. }
  52. }
  53. else if (__builtin_expect (z == 0.0f, 0) && isfinite (x) && isfinite (y)
  54. && _LIB_VERSION != _IEEE_)
  55. {
  56. if (x == 0.0f)
  57. {
  58. if (y == 0.0f)
  59. /* pow(0.0,0.0) */
  60. return __kernel_standard_f (x, y, 120);
  61. }
  62. else
  63. /* pow underflow */
  64. return __kernel_standard_f (x, y, 122);
  65. }
  66. return z;
  67. #else
  68. return (float) __ieee754_pow ((double) x, (double) y);
  69. #endif /* __UCLIBC_HAS_FENV__ */
  70. }