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/*
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 * Copyright (c) 2001-2004 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup sync
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 * @{
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 */
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/** @file
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 */
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#ifndef KERN_RWLOCK_H_
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#define KERN_RWLOCK_H_
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#include <arch/types.h>
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#include <synch/mutex.h>
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#include <synch/synch.h>
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#include <synch/spinlock.h>
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typedef enum {
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    RWLOCK_NONE,
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    RWLOCK_READER,
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    RWLOCK_WRITER
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} rwlock_type_t;
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typedef struct {
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    SPINLOCK_DECLARE(lock);
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    /**
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     * Mutex for writers, readers can bypass it if readers_in is positive.
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     */
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    mutex_t exclusive;
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    /** Number of readers in critical section. */
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    size_t readers_in;
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} rwlock_t;
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#define rwlock_write_lock(rwl) \
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    _rwlock_write_lock_timeout((rwl), SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE)
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#define rwlock_read_lock(rwl) \
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    _rwlock_read_lock_timeout((rwl), SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE)
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#define rwlock_write_trylock(rwl) \
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    _rwlock_write_lock_timeout((rwl), SYNCH_NO_TIMEOUT, \
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        SYNCH_FLAGS_NON_BLOCKING)
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#define rwlock_read_trylock(rwl) \
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    _rwlock_read_lock_timeout((rwl), SYNCH_NO_TIMEOUT, \
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        SYNCH_FLAGS_NON_BLOCKING)
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#define rwlock_write_lock_timeout(rwl, usec) \
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    _rwlock_write_lock_timeout((rwl), (usec), SYNCH_FLAGS_NONE)
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#define rwlock_read_lock_timeout(rwl, usec) \
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    _rwlock_read_lock_timeout((rwl), (usec), SYNCH_FLAGS_NONE)
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extern void rwlock_initialize(rwlock_t *rwl);
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extern void rwlock_read_unlock(rwlock_t *rwl);
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extern void rwlock_write_unlock(rwlock_t *rwl);
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extern int _rwlock_read_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
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extern int _rwlock_write_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
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#endif
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/** @}
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 */