chromium / native_client / nacl-gcc / f80d6b9ee7f94755c697ffb7194fb01dd0c537dd / . / mpfr-2.4.1 / uceil_exp2.c

/* __gmpfr_ceil_exp2 - returns y >= 2^d | |

Copyright 1999, 2000, 2001, 2002, 2003, 2004, 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" | |

/* returns y >= 2^d, assuming that d <= 1024 | |

for d integer, returns exactly 2^d | |

*/ | |

double | |

__gmpfr_ceil_exp2 (double d) | |

{ | |

long exp; | |

#if _GMP_IEEE_FLOATS | |

union ieee_double_extract x; | |

#else | |

struct {double d;} x; | |

#endif | |

MPFR_ASSERTN(d <= 1024.0); | |

exp = (long) d; | |

if (d != (double) exp) | |

exp++; | |

/* now exp = ceil(d) */ | |

x.d = 1.0; | |

#if _GMP_IEEE_FLOATS | |

x.s.exp = exp <= -1022 ? 1 : 1023 + exp; | |

#else | |

if (exp >= 0) | |

{ | |

while (exp != 0) | |

{ | |

x.d *= 2.0; | |

exp--; | |

} | |

} | |

else | |

{ | |

while (exp != 0) | |

{ | |

x.d *= (1.0 / 2.0); | |

exp++; | |

} | |

} | |

#endif | |

return x.d; | |

} |