1 /* Default read-write lock implementation struct definitions. 2 Copyright (C) 2019-2021 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 (such as lock-elision). The struct have a size 27 of 32 bytes on both LP32 and LP64 architectures. */ 28 29 struct __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