sem.c

xenomai 很好的linux实时补丁

/**
 *
 * @note Copyright (C) 2004 Philippe Gerum <[e-mail]> 
 * @note Copyright (C) 2005 Nextream France S.A.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <nucleus/pod.h>
#include <nucleus/synch.h>
#include <rtai/sem.h>
#include <rtai/task.h>

void rt_typed_sem_init (SEM *sem, int value, int type)

{
    int mode = XNSYNCH_PRIO;

    if ((type & RES_SEM) == RES_SEM)
	{
	mode |= XNSYNCH_PIP;
	value = 0; /* We will use this as a lock count. */
	}
    else
	{
	if ((type & BIN_SEM) && value > 1)
	    value = 1;

	if ((type & FIFO_Q) != 0)
	    mode = XNSYNCH_FIFO;
	}

    xnsynch_init(&sem->synch_base,mode);
    sem->count = value;
    sem->type = type & 0x3;
    sem->owner = NULL;
    sem->magic = RTAI_SEM_MAGIC;
}

int rt_sem_delete (SEM *sem)

{
    int err = 0, rc;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    sem = rtai_h2obj_validate(sem,RTAI_SEM_MAGIC,SEM);

    if (!sem)
	{
	err = SEM_ERR;
	goto unlock_and_exit;
	}

    rc = xnsynch_destroy(&sem->synch_base);

    rtai_mark_deleted(sem);

    if (rc == XNSYNCH_RESCHED)
        xnpod_schedule();

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

int rt_sem_signal (SEM *sem)

{
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    sem = rtai_h2obj_validate(sem,RTAI_SEM_MAGIC,SEM);

    if (!sem)
	{
	err = SEM_ERR;
	goto unlock_and_exit;
	}

    if (sem->type == RES_SEM)
	{
	if (rtai_current_task() != sem->owner)
	    {
	    /* <!> This is stricter than the original implementation. */
	    err = SEM_ERR;
	    goto unlock_and_exit;
	    }

	if (--sem->count > 0)	/* Recursion counter. */
	    goto unlock_and_exit;

	sem->owner = thread2rtask(xnsynch_wakeup_one_sleeper(&sem->synch_base));

	if (sem->owner != NULL)
	    xnpod_schedule();
	}
    else if (xnsynch_wakeup_one_sleeper(&sem->synch_base) != NULL)
	xnpod_schedule();
    else if (sem->type == CNT_SEM)
	sem->count++;
    else
	sem->count = 1;

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

int rt_sem_wait (SEM *sem)

{
    RT_TASK *task;
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    sem = rtai_h2obj_validate(sem,RTAI_SEM_MAGIC,SEM);

    if (!sem)
	{
	err = SEM_ERR;
	goto unlock_and_exit;
	}

    task = rtai_current_task();

    if (sem->type == RES_SEM)
	{
	if (sem->owner == NULL)
	    {
	    xnsynch_set_owner(&sem->synch_base,&task->thread_base);
	    sem->owner = task;
	    err = sem->count = 1; /* Initial lock. */
	    goto unlock_and_exit;
	    }
	else if (sem->owner == task) /* Recursive lock. */
	    {
	    err = ++sem->count;
	    goto unlock_and_exit;
	    }
	}
    else if (sem->count > 0)
	{
        err = sem->count--;
	goto unlock_and_exit;
	}

    xnsynch_sleep_on(&sem->synch_base,XN_INFINITE);
    
    if (xnthread_test_flags(&task->thread_base,XNRMID))
	err = SEM_ERR; /* Semaphore deleted while pending. */
    else if (xnthread_test_flags(&task->thread_base,XNBREAK))
	err = -EINTR; /* Unblocked.*/

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

int rt_sem_wait_if (SEM *sem)

{
    RT_TASK *task;
    int err = 0;
    spl_t s;

    xnlock_get_irqsave(&nklock,s);

    sem = rtai_h2obj_validate(sem,RTAI_SEM_MAGIC,SEM);

    if (!sem)
	{
	err = SEM_ERR;
	goto unlock_and_exit;
	}

    task = rtai_current_task();

    if (sem->type == RES_SEM)
	{
	if (sem->owner == NULL)
	    {
	    xnsynch_set_owner(&sem->synch_base,&task->thread_base);
	    sem->owner = task;
	    err = sem->count = 1; /* Initial lock. */
	    }
	else if (sem->owner == task) /* Recursive lock. */
	    err = ++sem->count;
	}
    else if (sem->count > 0)
        err = sem->count--;

 unlock_and_exit:

    xnlock_put_irqrestore(&nklock,s);

    return err;
}

int __rtai_sem_pkg_init (void)

{
    return 0;
}

void __rtai_sem_pkg_cleanup (void)

{
}

EXPORT_SYMBOL(rt_typed_sem_init);
EXPORT_SYMBOL(rt_sem_delete);
EXPORT_SYMBOL(rt_sem_signal);
EXPORT_SYMBOL(rt_sem_wait);
EXPORT_SYMBOL(rt_sem_wait_if);