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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.
 */


/** @addtogroup time
 * @{
 */


/**
 * @file
 * @brief   Timeout management functions.
 */


#include <time/timeout.h>
#include <typedefs.h>
#include <arch/types.h>
#include <config.h>
#include <panic.h>
#include <synch/spinlock.h>
#include <func.h>
#include <cpu.h>
#include <arch/asm.h>
#include <arch.h>


/** Initialize timeouts
 *
 * Initialize kernel timeouts.
 *
 */

void timeout_init(void)
{
    spinlock_initialize(&CPU->timeoutlock, "timeout_lock");
    list_initialize(&CPU->timeout_active_head);
}


/** Reinitialize timeout
 *
 * Initialize all members except the lock.
 *
 * @param t Timeout to be initialized.
 *
 */

void timeout_reinitialize(timeout_t *t)
{
    t->cpu = NULL;
    t->ticks = 0;
    t->handler = NULL;
    t->arg = NULL;
    link_initialize(&t->link);
}


/** Initialize timeout
 *
 * Initialize all members including the lock.
 *
 * @param t Timeout to be initialized.
 *
 */

void timeout_initialize(timeout_t *t)
{
    spinlock_initialize(&t->lock, "timeout_t_lock");
    timeout_reinitialize(t);
}


/** Register timeout
 *
 * Insert timeout handler f (with argument arg)
 * to timeout list and make it execute in
 * time microseconds (or slightly more).
 *
 * @param t    Timeout structure.
 * @param time Number of usec in the future to execute
 *             the handler.
 * @param f    Timeout handler function.
 * @param arg  Timeout handler argument.
 *
 */

void timeout_register(timeout_t *t, __u64 time, timeout_handler_t f, void *arg)
{
    timeout_t *hlp = NULL;
    link_t *l, *m;
    ipl_t ipl;
    __u64 sum;

    ipl = interrupts_disable();
    spinlock_lock(&CPU->timeoutlock);
    spinlock_lock(&t->lock);

    if (t->cpu)
        panic("t->cpu != 0");

    t->cpu = CPU;
    t->ticks = us2ticks(time);
   
    t->handler = f;
    t->arg = arg;

    /*
     * Insert t into the active timeouts list according to t->ticks.
     */

    sum = 0;
    l = CPU->timeout_active_head.next;
    while (l != &CPU->timeout_active_head) {
        hlp = list_get_instance(l, timeout_t, link);
        spinlock_lock(&hlp->lock);
        if (t->ticks < sum + hlp->ticks) {
            spinlock_unlock(&hlp->lock);
            break;
        }
        sum += hlp->ticks;
        spinlock_unlock(&hlp->lock);
        l = l->next;
    }

    m = l->prev;
    list_prepend(&t->link, m); /* avoid using l->prev */

    /*
     * Adjust t->ticks according to ticks accumulated in h's predecessors.
     */

    t->ticks -= sum;

    /*
     * Decrease ticks of t's immediate succesor by t->ticks.
     */

    if (l != &CPU->timeout_active_head) {
        spinlock_lock(&hlp->lock);
        hlp->ticks -= t->ticks;
        spinlock_unlock(&hlp->lock);
    }

    spinlock_unlock(&t->lock);
    spinlock_unlock(&CPU->timeoutlock);
    interrupts_restore(ipl);
}


/** Unregister timeout
 *
 * Remove timeout from timeout list.
 *
 * @param t Timeout to unregister.
 *
 * @return true on success, false on failure.
 */

bool timeout_unregister(timeout_t *t)
{
    timeout_t *hlp;
    link_t *l;
    ipl_t ipl;

grab_locks:
    ipl = interrupts_disable();
    spinlock_lock(&t->lock);
    if (!t->cpu) {
        spinlock_unlock(&t->lock);
        interrupts_restore(ipl);
        return false;
    }
    if (!spinlock_trylock(&t->cpu->timeoutlock)) {
        spinlock_unlock(&t->lock);
        interrupts_restore(ipl);       
        goto grab_locks;
    }
   
    /*
     * Now we know for sure that t hasn't been activated yet
     * and is lurking in t->cpu->timeout_active_head queue.
     */


    l = t->link.next;
    if (l != &t->cpu->timeout_active_head) {
        hlp = list_get_instance(l, timeout_t, link);
        spinlock_lock(&hlp->lock);
        hlp->ticks += t->ticks;
        spinlock_unlock(&hlp->lock);
    }
   
    list_remove(&t->link);
    spinlock_unlock(&t->cpu->timeoutlock);

    timeout_reinitialize(t);
    spinlock_unlock(&t->lock);

    interrupts_restore(ipl);
    return true;
}

/** @}
 */