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/* Low-level lock implementation. Mach gsync-based version.
Copyright (C) 1994-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _MACH_LOWLEVELLOCK_H
#define _MACH_LOWLEVELLOCK_H 1
#include <mach/gnumach.h>
#include <atomic.h>
/* Gsync flags. */
#ifndef GSYNC_SHARED
# define GSYNC_SHARED 0x01
# define GSYNC_QUAD 0x02
# define GSYNC_TIMED 0x04
# define GSYNC_BROADCAST 0x08
# define GSYNC_MUTATE 0x10
#endif
/* Static initializer for low-level locks. */
#define LLL_INITIALIZER 0
/* Wait on address PTR, without blocking if its contents
* are different from VAL. */
#define lll_wait(ptr, val, flags) \
__gsync_wait (__mach_task_self (), \
(vm_offset_t)(ptr), (val), 0, 0, (flags))
/* Wake one or more threads waiting on address PTR. */
#define lll_wake(ptr, flags) \
__gsync_wake (__mach_task_self (), (vm_offset_t)(ptr), 0, (flags))
/* Acquire the lock at PTR. */
#define lll_lock(ptr, flags) \
({ \
int *__iptr = (int *)(ptr); \
int __flags = (flags); \
if (*__iptr != 0 \
|| atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) != 0) \
while (1) \
{ \
if (atomic_exchange_acq (__iptr, 2) == 0) \
break; \
lll_wait (__iptr, 2, __flags); \
} \
(void)0; \
})
/* Try to acquire the lock at PTR, without blocking.
Evaluates to zero on success. */
#define lll_trylock(ptr) \
({ \
int *__iptr = (int *)(ptr); \
*__iptr == 0 \
&& atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) == 0 ? 0 : -1; \
})
/* Release the lock at PTR. */
#define lll_unlock(ptr, flags) \
({ \
int *__iptr = (int *)(ptr); \
if (atomic_exchange_rel (__iptr, 0) == 2) \
lll_wake (__iptr, (flags)); \
(void)0; \
})
#endif
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