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1 jermar 1 
/*
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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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/**
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 * @file    condvar.c
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 * @brief   Condition variables.
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 */
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#include <synch/condvar.h>
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#include <synch/mutex.h>
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#include <synch/waitq.h>
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#include <synch/synch.h>
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#include <arch.h>
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#include <typedefs.h>
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/** Initialize condition variable.
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 *
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 * @param cv Condition variable.
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 */
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void condvar_initialize(condvar_t *cv)
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{
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    waitq_initialize(&cv->wq);
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}
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/**
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 * Signal the condition has become true
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 * to the first waiting thread by waking it up.
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 *
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 * @param cv Condition variable.
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 */
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void condvar_signal(condvar_t *cv)
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{
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    waitq_wakeup(&cv->wq, WAKEUP_FIRST);
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}
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/**
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 * Signal the condition has become true
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 * to all waiting threads by waking them up.
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 *
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 * @param cv Condition variable.
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 */
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void condvar_broadcast(condvar_t *cv)
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{
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    waitq_wakeup(&cv->wq, WAKEUP_ALL);
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}
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/** Wait for the condition becoming true.
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 *
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 * @param cv Condition variable.
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 * @param mtx Mutex.
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 * @param usec Timeout value in microseconds.
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 *
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 * For exact description of meaning of possible values of usec,
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 * see comment for waitq_sleep_timeout().
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 *
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 * @return See comment for waitq_sleep_timeout().
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 */
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int _condvar_wait_timeout(condvar_t *cv, mutex_t *mtx, __u32 usec)
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{
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    int rc;
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    ipl_t ipl;
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    ipl = waitq_sleep_prepare(&cv->wq);
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    mutex_unlock(mtx);
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    cv->wq.missed_wakeups = 0;  /* Enforce blocking. */
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    rc = waitq_sleep_timeout_unsafe(&cv->wq, usec, SYNCH_BLOCKING);
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    mutex_lock(mtx);
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    waitq_sleep_finish(&cv->wq, rc, ipl);
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    return rc;
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}