/*
 * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
 * 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. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND 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 INSTITUTE OR 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.
 *
 * This file is part of the Contiki operating system.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * $Id: pt.h,v 1.3 2008/10/14 12:46:39 nvt-se Exp $
 */

/**
 * \addtogroup pt
 * @{
 */

/**
 * \file
 * Protothreads implementation.
 * \author
 * Adam Dunkels <adam@sics.se>
 *
 */
#ifndef __PT_H__
#define __PT_H__

#include "sys/lc.h"

struct pt
{
	lc_t	lc;
};

#define PT_WAITING	0
#define PT_YIELDED	1
#define PT_EXITED	2
#define PT_ENDED	3

/**
 * \name Initialization
 * @{
 */

/**
 * Initialize a protothread.
 *
 * Initializes a protothread. Initialization must be done prior to
 * starting to execute the protothread.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \sa PT_SPAWN()
 *
 * \hideinitializer
 */
#define PT_INIT( pt )	LC_INIT( (pt)->lc )

/** @} */

/**
 * \name Declaration and definition
 * @{
 */

/**
 * Declaration of a protothread.
 *
 * This macro is used to declare a protothread. All protothreads must
 * be declared with this macro.
 *
 * \param name_args The name and arguments of the C function
 * implementing the protothread.
 *
 * \hideinitializer
 */
#define PT_THREAD( name_args )	char name_args

/**
 * Declare the start of a protothread inside the C function
 * implementing the protothread.
 *
 * This macro is used to declare the starting point of a
 * protothread. It should be placed at the start of the function in
 * which the protothread runs. All C statements above the PT_BEGIN()
 * invokation will be executed each time the protothread is scheduled.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \hideinitializer
 */
#define PT_BEGIN( pt )			   \
	{							   \
		char	PT_YIELD_FLAG = 1; \
		LC_RESUME( (pt)->lc )

/**
 * Declare the end of a protothread.
 *
 * This macro is used for declaring that a protothread ends. It must
 * always be used together with a matching PT_BEGIN() macro.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \hideinitializer
 */
#define PT_END( pt )	\
	LC_END( (pt)->lc ); \
	PT_YIELD_FLAG = 0;	\
	PT_INIT( pt );		\
	return PT_ENDED;	\
}

/** @} */

/**
 * \name Blocked wait
 * @{
 */

/**
 * Block and wait until condition is true.
 *
 * This macro blocks the protothread until the specified condition is
 * true.
 *
 * \param pt A pointer to the protothread control structure.
 * \param condition The condition.
 *
 * \hideinitializer
 */
#define PT_WAIT_UNTIL( pt, condition ) \
	do								   \
	{								   \
		LC_SET( (pt)->lc );			   \
		if( !(condition) )			   \
		{							   \
			return PT_WAITING;		   \
		}							   \
	} while( 0 )

/**
 * Block and wait while condition is true.
 *
 * This function blocks and waits while condition is true. See
 * PT_WAIT_UNTIL().
 *
 * \param pt A pointer to the protothread control structure.
 * \param cond The condition.
 *
 * \hideinitializer
 */
#define PT_WAIT_WHILE( pt, cond )	PT_WAIT_UNTIL( (pt), !(cond) )
	/** @} */

	/**
 * \name Hierarchical protothreads
 * @{
 */

/**
 * Block and wait until a child protothread completes.
 *
 * This macro schedules a child protothread. The current protothread
 * will block until the child protothread completes.
 *
 * \note The child protothread must be manually initialized with the
 * PT_INIT() function before this function is used.
 *
 * \param pt A pointer to the protothread control structure.
 * \param thread The child protothread with arguments
 *
 * \sa PT_SPAWN()
 *
 * \hideinitializer
 */
#define PT_WAIT_THREAD( pt, thread )	PT_WAIT_WHILE( (pt), PT_SCHEDULE(thread) )

/**
 * Spawn a child protothread and wait until it exits.
 *
 * This macro spawns a child protothread and waits until it exits. The
 * macro can only be used within a protothread.
 *
 * \param pt A pointer to the protothread control structure.
 * \param child A pointer to the child protothread's control structure.
 * \param thread The child protothread with arguments
 *
 * \hideinitializer
 */
#define PT_SPAWN( pt, child, thread )	  \
	do									  \
	{									  \
		PT_INIT( (child) );				  \
		PT_WAIT_THREAD( (pt), (thread) ); \
	} while( 0 )

		/** @} */

		/**
 * \name Exiting and restarting
 * @{
 */

/**
 * Restart the protothread.
 *
 * This macro will block and cause the running protothread to restart
 * its execution at the place of the PT_BEGIN() call.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \hideinitializer
 */
#define PT_RESTART( pt )   \
	do					   \
	{					   \
		PT_INIT( pt );	   \
		return PT_WAITING; \
	} while( 0 )

/**
 * Exit the protothread.
 *
 * This macro causes the protothread to exit. If the protothread was
 * spawned by another protothread, the parent protothread will become
 * unblocked and can continue to run.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \hideinitializer
 */
#define PT_EXIT( pt )	  \
	do					  \
	{					  \
		PT_INIT( pt );	  \
		return PT_EXITED; \
	} while( 0 )
				/** @} */

				/**
 * \name Calling a protothread
 * @{
 */

/**
 * Schedule a protothread.
 *
 * This function schedules a protothread. The return value of the
 * function is non-zero if the protothread is running or zero if the
 * protothread has exited.
 *
 * \param f The call to the C function implementing the protothread to
 * be scheduled
 *
 * \hideinitializer
 */
#define PT_SCHEDULE( f )	( (f) < PT_EXITED )
				/** @} */

				/**
 * \name Yielding from a protothread
 * @{
 */

/**
 * Yield from the current protothread.
 *
 * This function will yield the protothread, thereby allowing other
 * processing to take place in the system.
 *
 * \param pt A pointer to the protothread control structure.
 *
 * \hideinitializer
 */
#define PT_YIELD( pt )			 \
	do							 \
	{							 \
		PT_YIELD_FLAG = 0;		 \
		LC_SET( (pt)->lc );		 \
		if( PT_YIELD_FLAG == 0 ) \
		{						 \
			return PT_YIELDED;	 \
		}						 \
	} while( 0 )

/**
 * \brief      Yield from the protothread until a condition occurs.
 * \param pt   A pointer to the protothread control structure.
 * \param cond The condition.
 *
 *             This function will yield the protothread, until the
 *             specified condition evaluates to true.
 *
 *
 * \hideinitializer
 */
#define PT_YIELD_UNTIL( pt, cond )			  \
	do										  \
	{										  \
		PT_YIELD_FLAG = 0;					  \
		LC_SET( (pt)->lc );					  \
		if( (PT_YIELD_FLAG == 0) || !(cond) ) \
		{									  \
			return PT_YIELDED;				  \
		}									  \
	} while( 0 )
						/** @} */
#endif /* __PT_H__ */

						/** @} */