math/w_log10_compat.c

   1 /* Copyright (C) 2011-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <fenv.h>
  19 #include <math.h>
  20 #include <math_private.h>
  21 #include <math-svid-compat.h>
  22 #include <libm-alias-double.h>
  23
  24
  25 #if LIBM_SVID_COMPAT
  26 /* wrapper log10(x) */
  27 double
  28 __log10 (double x)
  29 {
  30   if (__builtin_expect (islessequal (x, 0.0), 0) && _LIB_VERSION != _IEEE_)
  31     {
  32       if (x == 0.0)
  33         {
  34           __feraiseexcept (FE_DIVBYZERO);
  35           return __kernel_standard (x, x, 18); /* log10(0) */
  36         }
  37       else
  38         {
  39           __feraiseexcept (FE_INVALID);
  40           return __kernel_standard (x, x, 19); /* log10(x<0) */
  41         }
  42     }
  43
  44   return  __ieee754_log10 (x);
  45 }
  46 libm_alias_double (__log10, log10)
  47 #endif