math/w_llogb_template.c

   1 /* Wrapper to implement llogb in terms of ilogb.
   2    Copyright (C) 2012-2024 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 #include <math.h>
  20 #include <errno.h>
  21 #include <limits.h>
  22 #include <math_private.h>
  23 #include <fenv.h>
  24
  25 long int
  26 M_DECL_FUNC (__llogb) (FLOAT x)
  27 {
  28   int r = M_SUF (__ieee754_ilogb) (x);
  29   long int lr = r;
  30   if (__glibc_unlikely (r == FP_ILOGB0)
  31       || __glibc_unlikely (r == FP_ILOGBNAN)
  32       || __glibc_unlikely (r == INT_MAX))
  33     {
  34 #if LONG_MAX != INT_MAX
  35       if (r == FP_ILOGB0)
  36         lr = FP_LLOGB0;
  37       else if (r == FP_ILOGBNAN)
  38         lr = FP_LLOGBNAN;
  39       else
  40         lr = LONG_MAX;
  41 #endif
  42       __set_errno (EDOM);
  43       __feraiseexcept (FE_INVALID);
  44     }
  45   return lr;
  46 }
  47 declare_mgen_alias (__llogb, llogb)