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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2005-2009. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
/*
* Native ethread rwlocks on SPARC V9.
* Author: Mikael Pettersson.
*/
#ifndef ETHREAD_SPARC32_RWLOCK_H
#define ETHREAD_SPARC32_RWLOCK_H
/* Unlocked if zero, read-locked if positive, write-locked if -1. */
typedef struct {
volatile int lock;
} ethr_native_rwlock_t;
#ifdef ETHR_TRY_INLINE_FUNCS
static ETHR_INLINE void
ethr_native_rwlock_init(ethr_native_rwlock_t *lock)
{
lock->lock = 0;
}
static ETHR_INLINE void
ethr_native_read_unlock(ethr_native_rwlock_t *lock)
{
unsigned int old, new;
__asm__ __volatile__("membar #LoadLoad|#StoreLoad");
do {
old = lock->lock;
new = old-1;
__asm__ __volatile__(
"cas [%2], %1, %0"
: "=&r"(new)
: "r"(old), "r"(&lock->lock), "0"(new)
: "memory");
} while (__builtin_expect(old != new, 0));
}
static ETHR_INLINE int
ethr_native_read_trylock(ethr_native_rwlock_t *lock)
{
int old, new;
do {
old = lock->lock;
if (__builtin_expect(old < 0, 0))
return 0;
new = old+1;
__asm__ __volatile__(
"cas [%2], %1, %0"
: "=&r"(new)
: "r"(old), "r"(&lock->lock), "0"(new)
: "memory");
} while (__builtin_expect(old != new, 0));
__asm__ __volatile__("membar #StoreLoad|#StoreStore");
return 1;
}
static ETHR_INLINE int
ethr_native_read_is_locked(ethr_native_rwlock_t *lock)
{
return lock->lock < 0;
}
static ETHR_INLINE void
ethr_native_read_lock(ethr_native_rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(ethr_native_read_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("membar #LoadLoad");
} while (ethr_native_read_is_locked(lock));
}
}
static ETHR_INLINE void
ethr_native_write_unlock(ethr_native_rwlock_t *lock)
{
__asm__ __volatile__("membar #LoadStore|#StoreStore");
lock->lock = 0;
}
static ETHR_INLINE int
ethr_native_write_trylock(ethr_native_rwlock_t *lock)
{
unsigned int old, new;
do {
old = lock->lock;
if (__builtin_expect(old != 0, 0))
return 0;
new = -1;
__asm__ __volatile__(
"cas [%2], %1, %0"
: "=&r"(new)
: "r"(old), "r"(&lock->lock), "0"(new)
: "memory");
} while (__builtin_expect(old != new, 0));
__asm__ __volatile__("membar #StoreLoad|#StoreStore");
return 1;
}
static ETHR_INLINE int
ethr_native_write_is_locked(ethr_native_rwlock_t *lock)
{
return lock->lock != 0;
}
static ETHR_INLINE void
ethr_native_write_lock(ethr_native_rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(ethr_native_write_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("membar #LoadLoad");
} while (ethr_native_write_is_locked(lock));
}
}
#endif /* ETHR_TRY_INLINE_FUNCS */
#endif /* ETHREAD_SPARC32_RWLOCK_H */
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