/* ==== pthread_once.c =======================================================
 * Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by Chris Provenzano.
 * 4. The name of Chris Provenzano may not be used to endorse or promote 
 *	  products derived from this software without specific prior written
 *	  permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
 *
 * Description : pthread_once function.
 *
 *  1.00 93/12/12 proven
 *      -Started coding this file.
 */

#ifndef lint
static const char rcsid[] = "$Id: pthread_once.c,v 1.1 1994/02/07 22:04:27 proven Exp $ $provenid: pthread_once.c,v 1.4 1994/02/07 02:19:22 proven Exp $";
#endif

#include <pthread.h>

/* ==========================================================================
 * pthread_once()
 */
static pthread_mutex_t __pthread_once_mutex =  PTHREAD_MUTEX_INITIALIZER;

int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
{
	/* Check first for speed */
	if (*once_control == PTHREAD_ONCE_INIT) {
		pthread_mutex_lock(&__pthread_once_mutex);
		if (*once_control == PTHREAD_ONCE_INIT) {
			init_routine();
			(*once_control)++;
		}
		pthread_mutex_unlock(&__pthread_once_mutex);
	}
	return(OK);
}