chromium / native_client / nacl-gcc / f80d6b9ee7f94755c697ffb7194fb01dd0c537dd / . / mpfr-2.4.1 / int_ceil_log2.c

/* __gmpfr_int_ceil_log2 -- Integer ceil of log2(x) | |

Copyright 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. | |

Contributed by the Arenaire and Cacao projects, INRIA. | |

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

The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB. If not, write to | |

the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, | |

MA 02110-1301, USA. */ | |

#define MPFR_NEED_LONGLONG_H /* for count_leading_zeros */ | |

#include "mpfr-impl.h" | |

int | |

__gmpfr_int_ceil_log2 (unsigned long n) | |

{ | |

if (MPFR_UNLIKELY (n == 1)) | |

return 0; | |

else | |

{ | |

int b; | |

mp_limb_t limb; | |

MPFR_ASSERTN (n > 1); | |

limb = n - 1; | |

MPFR_ASSERTN (limb == n - 1); | |

count_leading_zeros (b, limb); | |

return BITS_PER_MP_LIMB - b; | |

} | |

} |