1 /* Machine-specific definition for spin locks. i386 version. 2 Copyright (C) 1994-2022 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 <https://www.gnu.org/licenses/>. */ 18 19 #ifndef _MACHINE_LOCK_H 20 #define _MACHINE_LOCK_H 21 22 /* The type of a spin lock variable. */ 23 24 typedef volatile int __spin_lock_t; 25 26 /* Value to initialize `__spin_lock_t' variables to. */ 27 28 #define __SPIN_LOCK_INITIALIZER 0 29 30 31 #ifndef _EXTERN_INLINE 32 #define _EXTERN_INLINE __extern_inline 33 #endif 34 35 /* Unlock LOCK. */ 36 37 extern void __spin_unlock (__spin_lock_t *__lock); 38 39 #if defined __USE_EXTERN_INLINES && defined _LIBC 40 _EXTERN_INLINE void __spin_unlock(__spin_lock_t * __lock)41__spin_unlock (__spin_lock_t *__lock) 42 { 43 register int __unlocked; 44 __asm__ __volatile ("xchgl %0, %1" 45 : "=&r" (__unlocked), "=m" (*__lock) : "0" (0) 46 : "memory"); 47 } 48 #endif 49 50 /* Try to lock LOCK; return nonzero if we locked it, zero if another has. */ 51 52 extern int __spin_try_lock (__spin_lock_t *__lock); 53 54 #if defined __USE_EXTERN_INLINES && defined _LIBC 55 _EXTERN_INLINE int __spin_try_lock(__spin_lock_t * __lock)56__spin_try_lock (__spin_lock_t *__lock) 57 { 58 register int __locked; 59 __asm__ __volatile ("xchgl %0, %1" 60 : "=&r" (__locked), "=m" (*__lock) : "0" (1) 61 : "memory"); 62 return !__locked; 63 } 64 #endif 65 66 /* Return nonzero if LOCK is locked. */ 67 68 extern int __spin_lock_locked (__spin_lock_t *__lock); 69 70 #if defined __USE_EXTERN_INLINES && defined _LIBC 71 _EXTERN_INLINE int __spin_lock_locked(__spin_lock_t * __lock)72__spin_lock_locked (__spin_lock_t *__lock) 73 { 74 return *__lock != 0; 75 } 76 #endif 77 78 79 #endif /* machine-lock.h */ 80