bits/libc-tsd.h

   1 /* libc-internal interface for thread-specific data.  Stub or TLS version.
   2    Copyright (C) 1998,2001,2002,2008 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, TYPE, KEY)  -- Define or declare a datum with TYPE
  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_address(TYPE, KEY)        -- Return the `TYPE *' pointing to
  32                                            the current thread's datum for KEY.
  33    __libc_tsd_get(TYPE, KEY)            -- Return the `TYPE' datum for KEY.
  34    __libc_tsd_set(TYPE, KEY, VALUE)     -- Set the datum for KEY to VALUE.
  35
  36    The set of available KEY's will usually be provided as an enum,
  37    and contains (at least):
  38                 _LIBC_TSD_KEY_MALLOC
  39                 _LIBC_TSD_KEY_DL_ERROR
  40                 _LIBC_TSD_KEY_RPC_VARS
  41    All uses must be the literal _LIBC_TSD_* name in the __libc_tsd_* macros.
  42    Some implementations may not provide any enum at all and instead
  43    using string pasting in the macros.  */
  44
  45 #include <tls.h>
  46
  47 /* When full support for __thread variables is available, this interface is
  48    just a trivial wrapper for it.  Without TLS, this is the generic/stub
  49    implementation for wholly single-threaded systems.
  50
  51    We don't define an enum for the possible key values, because the KEYs
  52    translate directly into variables by macro magic.  */
  53
  54 #if USE___THREAD
  55 # define __libc_tsd_define(CLASS, TYPE, KEY)    \
  56   CLASS __thread TYPE __libc_tsd_##KEY attribute_tls_model_ie;
  57
  58 # define __libc_tsd_address(TYPE, KEY)          (&__libc_tsd_##KEY)
  59 # define __libc_tsd_get(TYPE, KEY)              (__libc_tsd_##KEY)
  60 # define __libc_tsd_set(TYPE, KEY, VALUE)       (__libc_tsd_##KEY = (VALUE))
  61 #else
  62 # define __libc_tsd_define(CLASS, TYPE, KEY)    \
  63   CLASS TYPE __libc_tsd_##KEY##_data;
  64
  65 # define __libc_tsd_address(TYPE, KEY)          (&__libc_tsd_##KEY##_data)
  66 # define __libc_tsd_get(TYPE, KEY)              (__libc_tsd_##KEY##_data)
  67 # define __libc_tsd_set(TYPE, KEY, VALUE)       (__libc_tsd_##KEY##_data = (VALUE))
  68 #endif
  69
  70 #endif  /* bits/libc-tsd.h */