1/* Basic platform-independent macro definitions for mutexes,
2 thread-specific data and parameters for malloc.
3 Copyright (C) 2003-2016 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. */
35typedef 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
42#endif /* !defined mutex_init */
43
44#ifndef atomic_full_barrier
45# define atomic_full_barrier() __asm ("" ::: "memory")
46#endif
47
48#ifndef atomic_read_barrier
49# define atomic_read_barrier() atomic_full_barrier ()
50#endif
51
52#ifndef atomic_write_barrier
53# define atomic_write_barrier() atomic_full_barrier ()
54#endif
55
56#ifndef DEFAULT_TOP_PAD
57# define DEFAULT_TOP_PAD 131072
58#endif
59
60#endif /* !defined(_GENERIC_MALLOC_MACHINE_H) */
61