/*
 *  ____________________________________________________________________
 * 
 *  Copyright (c) 2002, Andrew N. Sloss, Chris Wright and Dominic Symes
 *  All rights reserved.
 *  ____________________________________________________________________
 * 
 *  NON-COMMERCIAL USE License
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions 
 *  are met: 
 *  
 *  1. For NON-COMMERCIAL USE only.
 * 
 *  2. Redistributions of source code must retain the above copyright 
 *     notice, this list of conditions and the following disclaimer. 
 * 
 *  3. 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. 
 * 
 *  4. All advertising materials mentioning features or use of this 
 *     software must display the following acknowledgement:
 * 
 *     This product includes software developed by Andrew N. Sloss,
 *     Chris Wright and Dominic Symes. 
 * 
 *   THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``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 CONTRIBUTORS 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. 
 * 
 *  If you have questions about this license or would like a different
 *  license please email :
 * 
 * 	andrew@sloss.net
 * 
 * 
 */
 
/*****************************************************************************
 * Simple Little Operating System - SLOS
 *****************************************************************************/

/*****************************************************************************
 *
 * Module       : mutex.h
 * Description  : Simple Mutual Exclusion module that allows 
 *                critical sections of code to have access to 
 *                shared memory.
 * OS           : SLOS 0.09 
 * Platform     : e7t
 * History      :
 *		
 * November 10th, 2001 Andrew N. Sloss
 * - started
 *
 * Notes        : none...
 *
 *****************************************************************************/

/*****************************************************************************
 * MACROS
 *****************************************************************************/

#define aWAIT 		while (semaphore==1) {} mutex_gatelock(); 
#define aSIGNAL 	mutex_gateunlock(); 	

#define bWAIT 		while (semaphore==1||semaphore==2) {} 	\
					mutex_gatelock();  

#define bSIGNAL 	mutex_gateunlock(); 

/*****************************************************************************
 * EXTERNAL
 *****************************************************************************/

extern unsigned volatile int semaphore; /* do not direct access */

/* -- mutex_gatelock ----------------------------------------------------------
 *
 * Description  : Locks the semaphore... 
 * 
 * Parameters   : none...
 * Return       : none...
 * Notes        :
 *
 */

void mutex_gatelock (void);

/* -- mutex_gateunlock --------------------------------------------------------
 *
 * Description  : Unlocks the semaphore ...
 * 
 * Parameters   : none...
 * Return       : none...
 * Notes        :
 *
 */

void mutex_gateunlock (void);