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/* $OpenBSD: _atomic_lock.c,v 1.2 2013/06/01 20:47:40 tedu Exp $ */
/*
* Copyright (c) 2005 Marco Peereboom <marco@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <machine/spinlock.h>
#ifdef DIAGNOSTIC
#include <stdio.h>
#include <stdlib.h>
#endif
int
_atomic_lock(volatile _atomic_lock_t *lock)
{
volatile _atomic_lock_t old;
#ifdef DIAGNOSTIC
if ((unsigned long)lock & 0xf) {
printf("lock not 16 byte aligned\n");
abort();
}
#endif
asm volatile ("ldcw 0(%2), %0"
: "=&r" (old), "+m" (lock)
: "r" (lock));
return (old == _ATOMIC_LOCK_LOCKED);
}
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