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/*

 * Copyright (C) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <time/clock.h>

#include <time/timeout.h>

#include <arch/types.h>

#include <config.h>

#include <synch/spinlock.h>

#include <synch/waitq.h>

#include <func.h>

#include <proc/scheduler.h>

#include <cpu.h>

#include <print.h>

#include <arch.h>

#include <list.h>

#include <arch/atomic.h>

#include <proc/thread.h>

/** Clock routine

 *

 * Clock routine executed from clock interrupt handler

 * (assuming interrupts_disable()'d). Runs expired timeouts

 * and preemptive scheduling.

 *

 */

void clock(void)

{

    link_t *l;

    timeout_t *h;

    timeout_handler_t f;

    void *arg;

    /*

     * To avoid lock ordering problems,

     * run all expired timeouts as you visit them.

     */

    spinlock_lock(&CPU->timeoutlock);

    while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {

        h = list_get_instance(l, timeout_t, link);

        spinlock_lock(&h->lock);

        if (h->ticks-- != 0) {

            spinlock_unlock(&h->lock);

            break;

        }

        list_remove(l);

        f = h->handler;

        arg = h->arg;

        timeout_reinitialize(h);

        spinlock_unlock(&h->lock); 

        spinlock_unlock(&CPU->timeoutlock);

        f(arg);

        spinlock_lock(&CPU->timeoutlock);

    }

    spinlock_unlock(&CPU->timeoutlock);

    /*

     * Do CPU usage accounting and find out whether to preempt THREAD.

     */

    if (THREAD) {

        __u64 ticks;

        spinlock_lock(&CPU->lock);

        CPU->needs_relink++;

        spinlock_unlock(&CPU->lock);   

        spinlock_lock(&THREAD->lock);

        if (ticks = THREAD->ticks)

            THREAD->ticks--;

        spinlock_unlock(&THREAD->lock);

        if (!ticks && !PREEMPTION_DISABLED) {

            scheduler();

        }

    }

}