third-party-mirror / GRTEv4 / 262be5abc585813b1766119db73641d44ba3741e / . / google3 / third_party / grte / v4_src / glibc-2.19 / math / w_log2.c

/* Copyright (C) 2011-2014 Free Software Foundation, Inc. | |

This file is part of the GNU C Library. | |

Contributed by Ulrich Drepper <drepper@gmail.com>, 2011. | |

The GNU C Library is free software; you can redistribute it and/or | |

modify it under the terms of the GNU Lesser General Public | |

License as published by the Free Software Foundation; either | |

version 2.1 of the License, or (at your option) any later version. | |

The GNU C Library is distributed in the hope that it will be useful, | |

but WITHOUT ANY WARRANTY; without even the implied warranty of | |

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |

Lesser General Public License for more details. | |

You should have received a copy of the GNU Lesser General Public | |

License along with the GNU C Library; if not, see | |

<http://www.gnu.org/licenses/>. */ | |

#include <fenv.h> | |

#include <math.h> | |

#include <math_private.h> | |

/* wrapper log2(x) */ | |

double | |

__log2 (double x) | |

{ | |

if (__builtin_expect (islessequal (x, 0.0), 0) && _LIB_VERSION != _IEEE_) | |

{ | |

if (x == 0.0) | |

{ | |

feraiseexcept (FE_DIVBYZERO); | |

return __kernel_standard (x, x, 48); /* log2(0) */ | |

} | |

else | |

{ | |

feraiseexcept (FE_INVALID); | |

return __kernel_standard (x, x, 49); /* log2(x<0) */ | |

} | |

} | |

return __ieee754_log2 (x); | |

} | |

weak_alias (__log2, log2) | |

#ifdef NO_LONG_DOUBLE | |

strong_alias (__log2, __log2l) | |

weak_alias (__log2, log2l) | |

#endif |