| /* Implementation of gamma function according to ISO C. |

| Copyright (C) 1997, 1999, 2002, 2004 Free Software Foundation, Inc. |

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

| Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and |

| Jakub Jelinek <jj@ultra.linux.cz, 1999. |

| |

| 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, write to the Free |

| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |

| 02111-1307 USA. */ |

| |

| #include "quadmath-imp.h" |

| |

| |

| __float128 |

| tgammaq (__float128 x) |

| { |

| /* We don't have a real gamma implementation now. We'll use lgamma |

| and the exp function. But due to the required boundary |

| conditions we must check some values separately. */ |

| int64_t hx; |

| uint64_t lx; |

| __float128 res; |

| int sign; |

| |

| GET_FLT128_WORDS64 (hx, lx, x); |

| |

| if (((hx & 0x7fffffffffffffffLL) | lx) == 0) |

| /* Return value for x == 0 is Inf with divide by zero exception. */ |

| return 1.0 / x; |

| |

| if (hx < 0 && (uint64_t) hx < 0xffff000000000000ULL && rintq (x) == x) |

| /* Return value for integer x < 0 is NaN with invalid exception. */ |

| return (x - x) / (x - x); |

| |

| if (hx == 0xffff000000000000ULL && lx == 0) |

| /* x == -Inf. According to ISO this is NaN. */ |

| return x - x; |

| |

| /* XXX FIXME. */ |

| res = expq (lgammaq (x)); |

| return signbitq (x) ? -res : res; |

| } |