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/* POSIX spinlock implementation. ia64 version.
Copyright (C) 2000 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Jes Sorensen <jes@linuxcare.com>
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; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <pthread.h>
#include "internals.h"
/* This implementation is inspired by the implementation used in the
Linux kernel. */
int
__pthread_spin_lock (pthread_spinlock_t *lock)
{
asm volatile
("mov ar.ccv = r0\n\t"
"mov r3 = 1\n\t"
";;\n"
"1:\n\t"
"ld4 r2 = %0\n\t"
";;\n\t"
"cmp4.eq p0, p7 = r0, r2\n\t"
"(p7) br.cond.spnt.few 1b \n\t"
"cmpxchg4.acq r2 = %0, r3, ar.ccv\n\t"
";;\n\t"
"cmp4.eq p0, p7 = r0, r2\n\t"
"(p7) br.cond.spnt.few 1b\n\t"
";;\n"
:: "m" (lock) : "r2", "r3", "p7", "memory");
return 0;
}
weak_alias (__pthread_spin_lock, pthread_spin_lock)
int
__pthread_spin_trylock (pthread_spinlock_t *lock)
{
int oldval;
asm volatile
("mov ar.ccv = r0\n\t"
"mov r2 = 1\n\t"
";;\n\t"
"cmpxchg4.acq %0 = %1, r2, ar.ccv\n\t"
";;\n"
: "=r" (oldval) : "m" (lock) : "r2", "memory");
return oldval > 0 ? 0 : EBUSY;
}
weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
int
__pthread_spin_unlock (pthread_spinlock_t *lock)
{
return *lock = 0;
}
weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
int
__pthread_spin_init (pthread_spinlock_t *lock, int pshared)
{
/* We can ignore the `pshared' parameter. Since we are busy-waiting
all processes which can access the memory location `lock' points
to can use the spinlock. */
return *lock = 0;
}
weak_alias (__pthread_spin_init, pthread_spin_init)
int
__pthread_spin_destroy (pthread_spinlock_t *lock)
{
/* Nothing to do. */
return 0;
}
weak_alias (__pthread_spin_destroy, pthread_spin_destroy)
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