1/* Default read-write lock implementation struct definitions.
2 Copyright (C) 2019-2026 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, see
17 <http://www.gnu.org/licenses/>. */
18
19#ifndef __RWLOCK_INTERNAL_H
20#define __RWLOCK_INTERNAL_H
21
22#include <bits/endian.h>
23
24/* Generic struct for both POSIX read-write lock. New ports are expected
25 to use the default layout, however archictetures can redefine it to add
26 arch-specific extensions. The struct have a size of 32 bytes on both LP32
27 and LP64 architectures. */
28
29struct __pthread_rwlock_arch_t
30{
31 unsigned int __readers;
32 unsigned int __writers;
33 unsigned int __wrphase_futex;
34 unsigned int __writers_futex;
35 unsigned int __pad3;
36 unsigned int __pad4;
37 /* FLAGS must stay at its position in the structure to maintain
38 binary compatibility. */
39#if __BYTE_ORDER == __BIG_ENDIAN
40 unsigned char __pad1;
41 unsigned char __pad2;
42 unsigned char __shared;
43 unsigned char __flags;
44#else
45 unsigned char __flags;
46 unsigned char __shared;
47 unsigned char __pad1;
48 unsigned char __pad2;
49#endif
50 int __cur_writer;
51};
52
53#if __BYTE_ORDER == __BIG_ENDIAN
54# define __PTHREAD_RWLOCK_INITIALIZER(__flags) \
55 0, 0, 0, 0, 0, 0, 0, 0, 0, __flags, 0
56#else
57# define __PTHREAD_RWLOCK_INITIALIZER(__flags) \
58 0, 0, 0, 0, 0, 0, __flags, 0, 0, 0, 0
59#endif
60
61#endif