cond_attr.c

xenomai 很好的linux实时补丁

/*
 * Written by Gilles Chanteperdrix <[e-mail]>.
 *
 * 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.
 */

/**
 * @addtogroup posix_cond
 *
 *@{*/

#include <posix/internal.h>

static pthread_condattr_t default_cond_attr = {

    magic: PSE51_COND_ATTR_MAGIC,
    clock: CLOCK_REALTIME
};


/**
 * Initialize a condition variable attributes object.
 *
 * This services initializes the condition variable attributes object @a attr
 * with default values for all attributes. Default value for the @a clock
 * attribute is @a CLOCK_REALTIME.
 *
 * Note that the @a pshared attribute is not supported: condition variables
 * created by Xenomai POSIX skin may be shared by kernel-space modules and
 * user-space processes through shared memory.
 *
 * If this service is called specifying a condition variable attributes object
 * that was already initialized, the attributes object is reinitialized.
 *
 * @param attr the condition variable attributes object to be initialized.
 *
 * @return 0 on success;
 * @return an error number if:
 * - ENOMEM, the condition variable attribute object pointer @a attr is @a
 *   NULL.
 *
 * @par Valid contexts:
 * - kernel module initialization or cleanup routine;
 * - Xenomai kernel-space real-time thread.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/pthread_condattr_init.html
 * 
 */
int pthread_condattr_init (pthread_condattr_t *attr)

{
    if (!attr)
        return ENOMEM;

    *attr = default_cond_attr;

    return 0;
}

/**
 * Destroy a condition variable attributes object.
 *
 * This service destroys the condition variable attributes object @a attr. The
 * object becomes invalid for all condition variable services (they all return
 * EINVAL) except pthread_condattr_init().
 *
 * @param attr the initialized mutex attributes object to be destroyed.
 *
 * @return 0 on success;
 * @return an error number if:
 * - EINVAL, the mutex attributes object @a attr is invalid.
 *
 * @par Valid contexts:
 * - kernel module initialization or cleanup routine;
 * - Xenomai kernel-space real-time thread.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/pthread_condattr_destroy.html
 * 
 */
int pthread_condattr_destroy (pthread_condattr_t *attr)

{
    spl_t s;

    xnlock_get_irqsave(&nklock, s);

    if (!pse51_obj_active(attr, PSE51_COND_ATTR_MAGIC, pthread_condattr_t))
	{
        xnlock_put_irqrestore(&nklock, s);
        return EINVAL;
	}
    
    pse51_mark_deleted(attr);
    xnlock_put_irqrestore(&nklock, s);

    return 0;
}

/**
 * Get the clock selection attribute from a condition variable attributes
 * object.
 *
 * This service stores, at the address @a clk_id, the value of the @a clock
 * attribute in the condition variable attributes object @a attr.
 *
 * See pthread_cond_timedwait() documentation for a description of the effect of
 * this attribute on a condition variable. The clock ID returned is @a
 * CLOCK_REALTIME or @a CLOCK_MONOTONIC.
 *
 * @param attr an initialized condition variable attributes object,
 *
 * @param clk_id address where the @a clock attribute value will be stored on
 * success.
 *
 * @return 0 on success,
 * @return an error number if:
 * - EINVAL, the attribute object @a attr is invalid.
 *
 * @par Valid contexts:
 * - kernel module initialization or cleanup routine;
 * - Xenomai kernel-space real-time thread.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/pthread_condattr_getclock.html
 * 
 */
int pthread_condattr_getclock (const pthread_condattr_t *attr, clockid_t *clk_id)

{
    spl_t s;

    xnlock_get_irqsave(&nklock, s);

    if (!pse51_obj_active(attr, PSE51_COND_ATTR_MAGIC, pthread_condattr_t))
	{
        xnlock_put_irqrestore(&nklock, s);
        return EINVAL;
	}

    *clk_id = attr->clock;
    xnlock_put_irqrestore(&nklock, s);

    return 0;
}

/**
 * Set the clock selection attribute of a condition variable attributes object.
 *
 * This service set the @a clock attribute of the condition variable attributes
 * object @a attr.
 *
 * See pthread_cond_timedwait() documentation for a description of the effect
 * of this attribute on a condition variable.
 *
 * @param attr an initialized condition variable attributes object,
 *
 * @param clk_id value of the @a clock attribute, may be @a CLOCK_REALTIME or @a
 * CLOCK_MONOTONIC.
 *
 * @return 0 on success,
 * @return an error number if:
 * - EINVAL, the condition variable attributes object @a attr is invalid;
 * - EINVAL, the value of @a clk_id is invalid for the @a clock attribute.
 *
 * @par Valid contexts:
 * - kernel module initialization or cleanup routine;
 * - Xenomai kernel-space real-time thread.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/pthread_condattr_setclock.html
 * 
 */
int pthread_condattr_setclock (pthread_condattr_t *attr, clockid_t clk_id)

{
    spl_t s;

    xnlock_get_irqsave(&nklock, s);

    if (!pse51_obj_active(attr, PSE51_COND_ATTR_MAGIC, pthread_condattr_t))
	{
        xnlock_put_irqrestore(&nklock, s);
        return EINVAL;
	}

    switch (clk_id)
	{
	default:

	    xnlock_put_irqrestore(&nklock, s);
	    return EINVAL;

	case CLOCK_REALTIME:
	case CLOCK_MONOTONIC:
	    break;
	}

    attr->clock = clk_id;
    xnlock_put_irqrestore(&nklock, s);

    return 0;
}

/*@}*/

EXPORT_SYMBOL(pthread_condattr_init);
EXPORT_SYMBOL(pthread_condattr_destroy);
EXPORT_SYMBOL(pthread_condattr_getclock);
EXPORT_SYMBOL(pthread_condattr_setclock);