sysdeps/generic/malloc-machine.h

   1 /* Basic platform-independent macro definitions for mutexes,
   2    thread-specific data and parameters for malloc.
   3    Copyright (C) 2003-2015 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _GENERIC_MALLOC_MACHINE_H
  21 #define _GENERIC_MALLOC_MACHINE_H
  22
  23 #include <atomic.h>
  24
  25 #ifndef mutex_init /* No threads, provide dummy macros */
  26
  27 # define NO_THREADS
  28
  29 /* The mutex functions used to do absolutely nothing, i.e. lock,
  30    trylock and unlock would always just return 0.  However, even
  31    without any concurrently active threads, a mutex can be used
  32    legitimately as an `in use' flag.  To make the code that is
  33    protected by a mutex async-signal safe, these macros would have to
  34    be based on atomic test-and-set operations, for example. */
  35 typedef int mutex_t;
  36
  37 # define mutex_init(m)          (*(m) = 0)
  38 # define mutex_lock(m)          ({ *(m) = 1; 0; })
  39 # define mutex_trylock(m)       (*(m) ? 1 : ((*(m) = 1), 0))
  40 # define mutex_unlock(m)        (*(m) = 0)
  41 # define MUTEX_INITIALIZER      (0)
  42
  43 typedef void *tsd_key_t;
  44 # define tsd_key_create(key, destr) do {} while(0)
  45 # define tsd_setspecific(key, data) ((key) = (data))
  46 # define tsd_getspecific(key, vptr) (vptr = (key))
  47
  48 # define thread_atfork(prepare, parent, child) do {} while(0)
  49
  50 #endif /* !defined mutex_init */
  51
  52 #ifndef atomic_full_barrier
  53 # define atomic_full_barrier() __asm ("" ::: "memory")
  54 #endif
  55
  56 #ifndef atomic_read_barrier
  57 # define atomic_read_barrier() atomic_full_barrier ()
  58 #endif
  59
  60 #ifndef atomic_write_barrier
  61 # define atomic_write_barrier() atomic_full_barrier ()
  62 #endif
  63
  64 #ifndef DEFAULT_TOP_PAD
  65 # define DEFAULT_TOP_PAD 131072
  66 #endif
  67
  68 #endif /* !defined(_GENERIC_MALLOC_MACHINE_H) */