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81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
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/* Machine-specific definition for spin locks. Alpha version.
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Copyright (C) 1994 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#ifndef _MACHINE_LOCK_H
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#define _MACHINE_LOCK_H
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/* The type of a spin lock variable. */
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typedef __volatile long int __spin_lock_t;
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/* Value to initialize `__spin_lock_t' variables to. */
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#define __SPIN_LOCK_INITIALIZER 0L
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#ifndef _EXTERN_INLINE
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#define _EXTERN_INLINE extern __inline
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#endif
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/* Unlock LOCK. */
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_EXTERN_INLINE void
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__spin_unlock (__spin_lock_t *__lock)
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{
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__asm__ __volatile__ ("mb; stq $31, %0; mb"
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: "=m" (__lock));
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}
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/* Try to lock LOCK; return nonzero if we locked it, zero if another has. */
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_EXTERN_INLINE int
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__spin_try_lock (register __spin_lock_t *__lock)
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{
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register long int __rtn, __tmp;
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do
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{
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__asm__ __volatile__ ("mb; ldq_l %0,%1" /* Load lock value into TMP. */
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: "=r" (__tmp) : "m" (*__lock));
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__rtn = 2; /* Load locked value into RTN. */
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if (__tmp)
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/* The lock is already taken. */
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return 0;
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/* The lock is not taken; try to get it now. */
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__asm__ __volatile__ ("stq_c %0,%1"
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: "=r" (__rtn), "=m" (*__lock)
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: "0" (__rtn), "1" (*__lock));
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/* RTN is clear if stq_c was interrupted; loop to try the lock again. */
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} while (! __rtn);
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/* RTN is now nonzero; we have the lock. */
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return __rtn;
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}
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/* Return nonzero if LOCK is locked. */
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_EXTERN_INLINE int
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__spin_lock_locked (__spin_lock_t *__lock)
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{
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return *__lock != 0;
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}
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#endif /* machine-lock.h */
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