bits/libc-tsd.h

   1 /* libc-internal interface for thread-specific data.  Stub or TLS version.
   2    Copyright (C) 1998,2001,02 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #ifndef _GENERIC_BITS_LIBC_TSD_H
  21 #define _GENERIC_BITS_LIBC_TSD_H 1
  22
  23 /* This file defines the following macros for accessing a small fixed
  24    set of thread-specific `void *' data used only internally by libc.
  25
  26    __libc_tsd_define(CLASS, KEY)        -- Define or declare a `void *' datum
  27                                            for KEY.  CLASS can be `static' for
  28                                            keys used in only one source file,
  29                                            empty for global definitions, or
  30                                            `extern' for global declarations.
  31    __libc_tsd_get(KEY)                  -- Return the `void *' datum for KEY.
  32    __libc_tsd_set(KEY, VALUE)           -- Set the datum for KEY to VALUE.
  33
  34    The set of available KEY's will usually be provided as an enum,
  35    and contains (at least):
  36                 _LIBC_TSD_KEY_MALLOC
  37                 _LIBC_TSD_KEY_DL_ERROR
  38                 _LIBC_TSD_KEY_RPC_VARS
  39    All uses must be the literal _LIBC_TSD_* name in the __libc_tsd_* macros.
  40    Some implementations may not provide any enum at all and instead
  41    using string pasting in the macros.  */
  42
  43 #include <tls.h>
  44
  45 /* When full support for __thread variables is available, this interface is
  46    just a trivial wrapper for it.  Without TLS, this is the generic/stub
  47    implementation for wholly single-threaded systems.
  48
  49    We don't define an enum for the possible key values, because the KEYs
  50    translate directly into variables by macro magic.  */
  51
  52 #if USE_TLS && HAVE___THREAD
  53 # define __libc_tsd_define(CLASS, KEY)  CLASS __thread void *__libc_tsd_##KEY;
  54
  55 # define __libc_tsd_get(KEY)            (__libc_tsd_##KEY)
  56 # define __libc_tsd_set(KEY, VALUE)     (__libc_tsd_##KEY = (VALUE))
  57 #else
  58 # define __libc_tsd_define(CLASS, KEY)  CLASS void *__libc_tsd_##KEY##_data;
  59
  60 # define __libc_tsd_get(KEY)            (__libc_tsd_##KEY##_data)
  61 # define __libc_tsd_set(KEY, VALUE)     (__libc_tsd_##KEY##_data = (VALUE))
  62 #endif
  63
  64 #endif  /* bits/libc-tsd.h */