math/w_tgamma_template.c

   1 /* Wrapper to set errno for tgamma.
   2    Copyright (C) 2017-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* Only build wrappers from the templates for the types that define the macro
  20    below.  This macro is set in math-type-macros-<type>.h in sysdeps/generic
  21    for each floating-point type.  */
  22 #if __USE_WRAPPER_TEMPLATE
  23
  24 # include <errno.h>
  25 # include <fenv.h>
  26 # include <math.h>
  27 # include <math_private.h>
  28
  29 #define M_CALL_FUNC_X(x) x ## _r
  30 #define M_CALL_FUNC(x) M_CALL_FUNC_X (x)
  31
  32 FLOAT
  33 M_DECL_FUNC (__tgamma) (FLOAT x)
  34 {
  35   int local_signgam;
  36   FLOAT y = M_CALL_FUNC (M_SUF (__ieee754_gamma)) (x, &local_signgam);
  37
  38   if (__glibc_unlikely (!isfinite (y) || y == 0)
  39       && (isfinite (x) || (isinf (x) && x < 0)))
  40     {
  41       if (x == 0)
  42         /* Pole error: tgamma(x=0).  */
  43         __set_errno (ERANGE);
  44       else if (M_SUF (floor) (x) == x && x < 0)
  45         /* Domain error: tgamma(integer x<0).  */
  46         __set_errno (EDOM);
  47       else
  48         /* Overflow or underflow.  */
  49         __set_errno (ERANGE);
  50     }
  51   return local_signgam < 0 ? -y : y;
  52 }
  53 declare_mgen_alias (__tgamma, tgamma)
  54
  55 #endif /* __USE_WRAPPER_TEMPLATE.  */