tcp.cc

diff serve for ns-2, work for version 2.29

/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1991-1997 Regents of the University of California.
 * 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 the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/tcp/tcp.cc,v 1.163 2005/06/21 01:48:24 sfloyd Exp $ (LBL)";
#endif

#include <stdlib.h>
#include <math.h>
#include <sys/types.h>
#include "ip.h"
#include "tcp.h"
#include "flags.h"
#include "random.h"
#include "basetrace.h"
#include "hdr_qs.h"

int hdr_tcp::offset_;

static class TCPHeaderClass : public PacketHeaderClass {
public:
        TCPHeaderClass() : PacketHeaderClass("PacketHeader/TCP",
					     sizeof(hdr_tcp)) {
		bind_offset(&hdr_tcp::offset_);
	}
} class_tcphdr;

static class TcpClass : public TclClass {
public:
	TcpClass() : TclClass("Agent/TCP") {}
	TclObject* create(int , const char*const*) {
		return (new TcpAgent());
	}
} class_tcp;

TcpAgent::TcpAgent() 
	: Agent(PT_TCP), 
	  t_seqno_(0), t_rtt_(0), t_srtt_(0), t_rttvar_(0), 
	  t_backoff_(0), ts_peer_(0), ts_echo_(0),
	  tss(NULL), tss_size_(100), 
	  rtx_timer_(this), delsnd_timer_(this), burstsnd_timer_(this), 
	  dupacks_(0), curseq_(0), highest_ack_(0), cwnd_(0), ssthresh_(0), 
	  maxseq_(0), count_(0), rtt_active_(0), rtt_seq_(-1), rtt_ts_(0.0), 
	  lastreset_(0.0), closed_(0), first_decrease_(1), fcnt_(0), 
	  nrexmit_(0), restart_bugfix_(1), cong_action_(0), 
	  ecn_burst_(0), ecn_backoff_(0), ect_(0), 
	  qs_requested_(0), qs_approved_(0),
	  qs_window_(0), qs_cwnd_(0), frto_(0)
	
{
#ifdef TCP_DELAY_BIND_ALL
#else /* ! TCP_DELAY_BIND_ALL */
	// not delay-bound because delay-bound tracevars aren't yet supported
	bind("t_seqno_", &t_seqno_);
	bind("rtt_", &t_rtt_);
	bind("srtt_", &t_srtt_);
	bind("rttvar_", &t_rttvar_);
	bind("backoff_", &t_backoff_);
	bind("dupacks_", &dupacks_);
	bind("seqno_", &curseq_);
	bind("ack_", &highest_ack_);
	bind("cwnd_", &cwnd_);
	bind("ssthresh_", &ssthresh_);
	bind("maxseq_", &maxseq_);
        bind("ndatapack_", &ndatapack_);
        bind("ndatabytes_", &ndatabytes_);
        bind("nackpack_", &nackpack_);
        bind("nrexmit_", &nrexmit_);
        bind("nrexmitpack_", &nrexmitpack_);
        bind("nrexmitbytes_", &nrexmitbytes_);
        bind("necnresponses_", &necnresponses_);
        bind("ncwndcuts_", &ncwndcuts_);
	bind("ncwndcuts1_", &ncwndcuts1_);
#endif /* TCP_DELAY_BIND_ALL */

}

void
TcpAgent::delay_bind_init_all()
{

        // Defaults for bound variables should be set in ns-default.tcl.
        delay_bind_init_one("window_");
        delay_bind_init_one("windowInit_");
        delay_bind_init_one("windowInitOption_");

        delay_bind_init_one("syn_");
        delay_bind_init_one("windowOption_");
        delay_bind_init_one("windowConstant_");
        delay_bind_init_one("windowThresh_");
        delay_bind_init_one("delay_growth_");
        delay_bind_init_one("overhead_");
        delay_bind_init_one("tcpTick_");
        delay_bind_init_one("ecn_");
        delay_bind_init_one("SetCWRonRetransmit_");
        delay_bind_init_one("old_ecn_");
        delay_bind_init_one("eln_");
        delay_bind_init_one("eln_rxmit_thresh_");
        delay_bind_init_one("packetSize_");
        delay_bind_init_one("tcpip_base_hdr_size_");
	delay_bind_init_one("ts_option_size_");
        delay_bind_init_one("bugFix_");
	delay_bind_init_one("bugFix_ack_");
	delay_bind_init_one("bugFix_ts_");
	delay_bind_init_one("lessCareful_");
        delay_bind_init_one("slow_start_restart_");
        delay_bind_init_one("restart_bugfix_");
        delay_bind_init_one("timestamps_");
	delay_bind_init_one("ts_resetRTO_");
        delay_bind_init_one("maxburst_");
	delay_bind_init_one("aggressive_maxburst_");
        delay_bind_init_one("maxcwnd_");
	delay_bind_init_one("numdupacks_");
	delay_bind_init_one("numdupacksFrac_");
	delay_bind_init_one("exitFastRetrans_");
        delay_bind_init_one("maxrto_");
	delay_bind_init_one("minrto_");
        delay_bind_init_one("srtt_init_");
        delay_bind_init_one("rttvar_init_");
        delay_bind_init_one("rtxcur_init_");
        delay_bind_init_one("T_SRTT_BITS");
        delay_bind_init_one("T_RTTVAR_BITS");
        delay_bind_init_one("rttvar_exp_");
        delay_bind_init_one("awnd_");
        delay_bind_init_one("decrease_num_");
        delay_bind_init_one("increase_num_");
	delay_bind_init_one("k_parameter_");
	delay_bind_init_one("l_parameter_");
        delay_bind_init_one("trace_all_oneline_");
        delay_bind_init_one("nam_tracevar_");

        delay_bind_init_one("QOption_");
        delay_bind_init_one("EnblRTTCtr_");
        delay_bind_init_one("control_increase_");
	delay_bind_init_one("noFastRetrans_");
	delay_bind_init_one("precisionReduce_");
	delay_bind_init_one("oldCode_");
	delay_bind_init_one("useHeaders_");
	delay_bind_init_one("low_window_");
	delay_bind_init_one("high_window_");
	delay_bind_init_one("high_p_");
	delay_bind_init_one("high_decrease_");
	delay_bind_init_one("max_ssthresh_");
	delay_bind_init_one("cwnd_range_");
	delay_bind_init_one("timerfix_");
	delay_bind_init_one("rfc2988_");
	delay_bind_init_one("singledup_");
	delay_bind_init_one("LimTransmitFix_");
	delay_bind_init_one("rate_request_");
	delay_bind_init_one("qs_enabled_");
	delay_bind_init_one("tcp_qs_recovery_");
	delay_bind_init_one("qs_request_mode_");
	delay_bind_init_one("qs_thresh_");
	delay_bind_init_one("qs_rtt_");

	delay_bind_init_one("frto_enabled_");
	delay_bind_init_one("sfrto_enabled_");
	delay_bind_init_one("spurious_response_");

#ifdef TCP_DELAY_BIND_ALL
	// out because delay-bound tracevars aren't yet supported
        delay_bind_init_one("t_seqno_");
        delay_bind_init_one("rtt_");
        delay_bind_init_one("srtt_");
        delay_bind_init_one("rttvar_");
        delay_bind_init_one("backoff_");
        delay_bind_init_one("dupacks_");
        delay_bind_init_one("seqno_");
        delay_bind_init_one("ack_");
        delay_bind_init_one("cwnd_");
        delay_bind_init_one("ssthresh_");
        delay_bind_init_one("maxseq_");
        delay_bind_init_one("ndatapack_");
        delay_bind_init_one("ndatabytes_");
        delay_bind_init_one("nackpack_");
        delay_bind_init_one("nrexmit_");
        delay_bind_init_one("nrexmitpack_");
        delay_bind_init_one("nrexmitbytes_");
        delay_bind_init_one("necnresponses_");
        delay_bind_init_one("ncwndcuts_");
	delay_bind_init_one("ncwndcuts1_");
#endif /* TCP_DELAY_BIND_ALL */

	Agent::delay_bind_init_all();

        reset();
}

int
TcpAgent::delay_bind_dispatch(const char *varName, const char *localName, TclObject *tracer)
{
        if (delay_bind(varName, localName, "window_", &wnd_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "windowInit_", &wnd_init_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "windowInitOption_", &wnd_init_option_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "syn_", &syn_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "windowOption_", &wnd_option_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "windowConstant_",  &wnd_const_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "windowThresh_", &wnd_th_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "delay_growth_", &delay_growth_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "overhead_", &overhead_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "tcpTick_", &tcp_tick_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "ecn_", &ecn_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "SetCWRonRetransmit_", &SetCWRonRetransmit_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "old_ecn_", &old_ecn_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "eln_", &eln_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "eln_rxmit_thresh_", &eln_rxmit_thresh_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "packetSize_", &size_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "tcpip_base_hdr_size_", &tcpip_base_hdr_size_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "ts_option_size_", &ts_option_size_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "bugFix_", &bug_fix_ , tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "bugFix_ack_", &bugfix_ack_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "bugFix_ts_", &bugfix_ts_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "lessCareful_", &less_careful_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "timestamps_", &ts_option_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "ts_resetRTO_", &ts_resetRTO_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "slow_start_restart_", &slow_start_restart_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "restart_bugfix_", &restart_bugfix_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "maxburst_", &maxburst_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "aggressive_maxburst_", &aggressive_maxburst_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "maxcwnd_", &maxcwnd_ , tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "numdupacks_", &numdupacks_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "numdupacksFrac_", &numdupacksFrac_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "exitFastRetrans_", &exitFastRetrans_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "maxrto_", &maxrto_ , tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "minrto_", &minrto_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "srtt_init_", &srtt_init_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rttvar_init_", &rttvar_init_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rtxcur_init_", &rtxcur_init_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "T_SRTT_BITS", &T_SRTT_BITS , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "T_RTTVAR_BITS", &T_RTTVAR_BITS , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rttvar_exp_", &rttvar_exp_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "awnd_", &awnd_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "decrease_num_", &decrease_num_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "increase_num_", &increase_num_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "k_parameter_", &k_parameter_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "l_parameter_", &l_parameter_, tracer)) return TCL_OK;


        if (delay_bind_bool(varName, localName, "trace_all_oneline_", &trace_all_oneline_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "nam_tracevar_", &nam_tracevar_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "QOption_", &QOption_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "EnblRTTCtr_", &EnblRTTCtr_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "control_increase_", &control_increase_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "noFastRetrans_", &noFastRetrans_, tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "precisionReduce_", &precision_reduce_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "oldCode_", &oldCode_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "useHeaders_", &useHeaders_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "low_window_", &low_window_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "high_window_", &high_window_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "high_p_", &high_p_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "high_decrease_", &high_decrease_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "max_ssthresh_", &max_ssthresh_, tracer)) return TCL_OK;
	if (delay_bind(varName, localName, "cwnd_range_", &cwnd_range_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "timerfix_", &timerfix_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "rfc2988_", &rfc2988_, tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "singledup_", &singledup_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "LimTransmitFix_", &LimTransmitFix_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rate_request_", &rate_request_ , tracer)) return TCL_OK;
        if (delay_bind_bool(varName, localName, "qs_enabled_", &qs_enabled_ , tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "tcp_qs_recovery_", &tcp_qs_recovery_, tracer)) return TCL_OK;

	if (delay_bind_bool(varName, localName, "frto_enabled_", &frto_enabled_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "sfrto_enabled_", &sfrto_enabled_, tracer)) return TCL_OK;
	if (delay_bind_bool(varName, localName, "spurious_response_", &spurious_response_, tracer)) return TCL_OK;


#ifdef TCP_DELAY_BIND_ALL
	// not if (delay-bound delay-bound tracevars aren't yet supported
        if (delay_bind(varName, localName, "t_seqno_", &t_seqno_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rtt_", &t_rtt_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "srtt_", &t_srtt_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "rttvar_", &t_rttvar_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "backoff_", &t_backoff_ , tracer)) return TCL_OK;

        if (delay_bind(varName, localName, "dupacks_", &dupacks_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "seqno_", &curseq_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "ack_", &highest_ack_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "cwnd_", &cwnd_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "ssthresh_", &ssthresh_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "maxseq_", &maxseq_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "ndatapack_", &ndatapack_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "ndatabytes_", &ndatabytes_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "nackpack_", &nackpack_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "nrexmit_", &nrexmit_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "nrexmitpack_", &nrexmitpack_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "nrexmitbytes_", &nrexmitbytes_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "necnresponses_", &necnresponses_ , tracer)) return TCL_OK;
        if (delay_bind(varName, localName, "ncwndcuts_", &ncwndcuts_ , tracer)) return TCL_OK;
 	if (delay_bind(varName, localName, "ncwndcuts1_", &ncwndcuts1_ , tracer)) return TCL_OK;

#endif

        return Agent::delay_bind_dispatch(varName, localName, tracer);
}

#define TCP_WRK_SIZE		512
/* Print out all the traced variables whenever any one is changed */
void
TcpAgent::traceAll() {
	if (!channel_)
		return;

	double curtime;
	Scheduler& s = Scheduler::instance();
	char wrk[TCP_WRK_SIZE];

	curtime = &s ? s.clock() : 0;
	snprintf(wrk, TCP_WRK_SIZE,
		 "time: %-8.5f saddr: %-2d sport: %-2d daddr: %-2d dport:"
		 " %-2d maxseq: %-4d hiack: %-4d seqno: %-4d cwnd: %-6.3f"
		 " ssthresh: %-3d dupacks: %-2d rtt: %-6.3f srtt: %-6.3f"
		 " rttvar: %-6.3f bkoff: %-d\n", curtime, addr(), port(),
		 daddr(), dport(), int(maxseq_), int(highest_ack_),
		 int(t_seqno_), double(cwnd_), int(ssthresh_),
		 int(dupacks_), int(t_rtt_)*tcp_tick_, 
		 (int(t_srtt_) >> T_SRTT_BITS)*tcp_tick_, 
		 int(t_rttvar_)*tcp_tick_/4.0, int(t_backoff_)); 
	(void)Tcl_Write(channel_, wrk, -1);
}

/* Print out just the variable that is modified */
void
TcpAgent::traceVar(TracedVar* v) 
{
	if (!channel_)
		return;

	double curtime;
	Scheduler& s = Scheduler::instance();
	char wrk[TCP_WRK_SIZE];

	curtime = &s ? s.clock() : 0;

	// XXX comparing addresses is faster than comparing names
	if (v == &cwnd_)
		snprintf(wrk, TCP_WRK_SIZE,
			 "%-8.5f %-2d %-2d %-2d %-2d %s %-6.3f\n",
			 curtime, addr(), port(), daddr(), dport(),
			 v->name(), double(*((TracedDouble*) v))); 
 	else if (v == &t_rtt_)
		snprintf(wrk, TCP_WRK_SIZE,
			 "%-8.5f %-2d %-2d %-2d %-2d %s %-6.3f\n",
			 curtime, addr(), port(), daddr(), dport(),
			 v->name(), int(*((TracedInt*) v))*tcp_tick_); 
	else if (v == &t_srtt_)
		snprintf(wrk, TCP_WRK_SIZE,
			 "%-8.5f %-2d %-2d %-2d %-2d %s %-6.3f\n",
			 curtime, addr(), port(), daddr(), dport(),
			 v->name(), 
			 (int(*((TracedInt*) v)) >> T_SRTT_BITS)*tcp_tick_); 
	else if (v == &t_rttvar_)
		snprintf(wrk, TCP_WRK_SIZE,
			 "%-8.5f %-2d %-2d %-2d %-2d %s %-6.3f\n",
			 curtime, addr(), port(), daddr(), dport(),
			 v->name(), 
			 int(*((TracedInt*) v))*tcp_tick_/4.0); 
	else
		snprintf(wrk, TCP_WRK_SIZE,
			 "%-8.5f %-2d %-2d %-2d %-2d %s %d\n",
			 curtime, addr(), port(), daddr(), dport(),
			 v->name(), int(*((TracedInt*) v))); 

	(void)Tcl_Write(channel_, wrk, -1);
}

void
TcpAgent::trace(TracedVar* v) 
{
	if (nam_tracevar_) {
		Agent::trace(v);
	} else if (trace_all_oneline_)
		traceAll();
	else 
		traceVar(v);
}

//
// in 1-way TCP, syn_ indicates we are modeling
// a SYN exchange at the beginning.  If this is true
// and we are delaying growth, then use an initial
// window of one.  If not, we do whatever initial_window()
// says to do.
//

void
TcpAgent::set_initial_window()
{
	if (syn_ && delay_growth_)
		cwnd_ = 1.0; 
	else
		cwnd_ = initial_window();
}

void
TcpAgent::reset_qoption()
{
	int now = (int)(Scheduler::instance().clock()/tcp_tick_ + 0.5);