/*
 * Active Router Transport Protocol (ARTP) implementation
 * Copyright (c) 2004, Tomas Rebok
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the "BSD License" which is
 * distributed with the software in the file LICENSE.
 *
 * 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 BSD
 * License for more details.
 */

/** @file
 * @c ARTP's configuraton file.
 * @author Tomas Rebok
 * @date 2004
 */


#ifndef ARTP_CONFIG_H
#define ARTP_CONFIG_H   1


/** defined macros that affects the protocol's behavior a lot */


/** Constant that define the ARTP's version.
 */
#define ARTP_VERSION 1


/** Link idle computing.
 * This macro says how to compute time when we want to decrease congestion
 * window size when connection is idle more than computed time.
 *
 * @param rto
 * 		actual retransmit timeout
 */
#define LINK_IDLE(rto) (2 * (rto))


/** Initial congestion window size
 *
 * @param mss
 * 		actual maximum segment size
 */
#define INITIAL_WINDOW_SIZE(mss) (3 * (mss))


/** Congestion window change after incoming acknowledgement.
 * This macro says how to change congestion window size when any 
 * acknowledgement came.
 *
 * @param mss
 * 		current maximum segment size
 *
 * @param old_cwnd
 * 		old size of congestion window
 */
#define CWND_ACK(mss, old_cwnd) ((mss) * (mss)) / (old_cwnd)


/** Congestion window multiplier after packet loss.
 * This constant defines multiplier when retransmission took place (packet loss
 * was detected).
 */
#define CWND_DOWN_MULTIPLIER 0.7


/** Congestion window change after packet loss.
 * This macro says how to compute new congestion window size after 
 * retransmission of any packet.
 *
 * @param mss
 * 		current maximum segment size
 *
 * @param old_cwnd
 * 		old size of congestion window
 */
#define CWND_RETRANS(mss, old_cwnd) \
	(CWND_DOWN_MULTIPLIER * (old_cwnd) >= INITIAL_WINDOW_SIZE(mss)) \
		? CWND_DOWN_MULTIPLIER * (old_cwnd) \
		: INITIAL_WINDOW_SIZE(mss);


/** Retransmit timeout computing.
 * This macro says how to compute packets' retransmit timeout after incoming
 * ackwnowledgement packet.
 *
 * @param srtt
 * 		actual smooth round trip time
 *
 * @param init_resend_time
 * 		initial retransmit timeout
 */
#define RTO_COMPUTE(srtt, init_resend_time) \
		(srtt > 0) ? (4 * (srtt)) : init_resend_time


/** Latest acknowledgement packet send time.
 * This macro says how to compute time when given acknowledgement packet has to
 * be sent (lately).
 * 
 * @param srtt
 * 		actual smooth round trip time
 */
#define LATEST_ACKS_SEND(srtt) ((srtt) / 2.0)


/** Smooth round trip time computing constant.
 */
#define SRTT_ALPHA 0.875


/** Smooth round trip time computing.
 * This macro says how to compute smooth round trip time when actual round
 * trip time and old smooth round trip time are given.
 *
 * @param rtt
 * 		actual round trip time
 *
 * @param old_srtt
 * 		old value of smooth round trip time
 */
#define SRTT_COMPUTE(rtt, old_srtt) \
	((old_srtt) == 0) ? rtt \
	                  : (SRTT_ALPHA * (old_srtt)) + ((1 - SRTT_ALPHA) * (rtt));


/** Time stamp delta computing constant (see below)
 */
#define TS_DELTA_ALPHA 0.875


/** Timestamp delta computing.
 * This macro says how to compute the difference between our time and our 
 * partner's time (timestamp delta).
 *
 * @param current_time
 * 		actual time
 *
 * @param sent_time
 * 		sent time of given acknowledgement packet
 *
 * @param srtt
 * 		actual smooth round trip time
 *
 * @param old_ts_delta
 * 		old value of timestamp delta
 */
#define TS_DELTA_COMPUTE(current_time, sent_time, srtt, old_ts_delta) \
	((old_ts_delta) == 0) ? (current_time) - ((sent_time) + (srtt) / 2.0) \
                          : (TS_DELTA_ALPHA * (old_ts_delta)) + \
						  ((1 - TS_DELTA_ALPHA) * ((current_time) \
											- ((sent_time) + (srtt) / 2.0)))
	
/* NOTE: Instead of smooth computing we can use absolute computing as showed 
 * here.
 *
 * #define TS_DELTA_COMPUTE(current_time, sent_time, srtt, old_ts_delta) \
	(current_time) - ((sent_time) + (srtt) / 2.0)
 */
	

/** Maximal incoming ARTP packet size */
#define MAX_ARTP_PACKET_SIZE 2048  


/** Maximal count of sequence numbers in one item of structure for searching
 * duplicities.
 */
#define DUPPLE_SEQ_COUNT 100000

	
/** Maximal read line length from config file */
#define MAX_CONFIG_LINE_LENGTH 1000
	

#endif

/* vim: set ts=4 : */