math/w_log2_compat.c

   1 /* Copyright (C) 2011-2024 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 && (SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_29) \
  26                          || defined NO_LONG_DOUBLE \
  27                          || defined LONG_DOUBLE_COMPAT)
  28 /* wrapper log2(x) */
  29 double
  30 __log2_compat (double x)
  31 {
  32   if (__builtin_expect (islessequal (x, 0.0), 0) && _LIB_VERSION != _IEEE_)
  33     {
  34       if (x == 0.0)
  35         {
  36           feraiseexcept (FE_DIVBYZERO);
  37           return __kernel_standard (x, x, 48); /* log2(0) */
  38         }
  39       else
  40         {
  41           feraiseexcept (FE_INVALID);
  42           return __kernel_standard (x, x, 49); /* log2(x<0) */
  43         }
  44     }
  45
  46   return  __ieee754_log2 (x);
  47 }
  48 # if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_29)
  49 compat_symbol (libm, __log2_compat, log2, GLIBC_2_1);
  50 # endif
  51 # ifdef NO_LONG_DOUBLE
  52 weak_alias (__log2_compat, log2l)
  53 # endif
  54 # ifdef LONG_DOUBLE_COMPAT
  55 /* Work around gas bug "multiple versions for symbol".  */
  56 weak_alias (__log2_compat, __log2_compat_alias)
  57
  58 LONG_DOUBLE_COMPAT_CHOOSE_libm_log2l (
  59   compat_symbol (libm, __log2_compat_alias, log2l, FIRST_VERSION_libm_log2l), );
  60 # endif
  61 #endif