chromium / native_client / nacl-gcc / f80d6b9ee7f94755c697ffb7194fb01dd0c537dd / . / mpfr-2.4.1 / powerof2.c

/* mpfr_powerof2_raw -- test whether a floating-point number is a power of 2 | |

Copyright 2002, 2003, 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. */ | |

#include "mpfr-impl.h" | |

/* This is an internal function and one assumes that x is a real number. */ | |

int | |

mpfr_powerof2_raw (mpfr_srcptr x) | |

{ | |

mp_limb_t *xp; | |

mp_size_t xn; | |

/* This is an internal function, and we may call it with some | |

wrong numbers (ie good mantissa but wrong flags or exp) | |

So we don't want to test if it is a pure FP. | |

MPFR_ASSERTN(MPFR_IS_PURE_FP(x)); */ | |

xp = MPFR_MANT(x); | |

xn = (MPFR_PREC(x) - 1) / BITS_PER_MP_LIMB; | |

/*if (NOT_POW2(xp[xn]))*/ | |

if (xp[xn] != MPFR_LIMB_HIGHBIT) | |

return 0; | |

while (xn > 0) | |

if (xp[--xn] != 0) | |

return 0; | |

return 1; | |

} |