wlan-chutil

柯老师网站上找到的

#!/bin/tcsh
#
# Channel utilization:
# works on a trace file produced by ns
# outputs idle time and the collision time on the channel between
# the first and the (possibly unfinished) last transmission
# for now: assumes that all MACs are on a single channel

if ( $#argv != 1 ) then
  echo usage:
  echo "      " $0 \<scenario\>
  exit 1
endif

set scenario = $1
set tracefile = $scenario.tr
set outfile = $scenario.channel
rm -f $outfile

egrep "\-Nl MAC " $tracefile | gawk -v busy=0 -v outf=$outfile '\
/^s/ {								\
	if (busy == 0) {					\
		if  (last_eot != 0) {				\
			idle += ($3 - last_eot);		\
		} else {					\
			first_send = $3;			\
		}						\
	}							\
	if (busy == 1) {					\
		start_collision = $3;				\
		++collisions;					\
	}							\
	print $3, busy >> outf;					\
	++busy;							\
	print $3, busy >> outf;					\
}								\
/^x/ {								\
	print $3, busy >> outf;					\
	--busy;							\
	print $3, busy >> outf;					\
	if (busy < 0) {						\
		print "Fatal Error: EOT without send";		\
	}							\
	if (busy == 1) {					\
		collision += ($3 - start_collision);		\
	}							\
	if (busy == 0) {					\
		last_eot = $3;					\
		++total;					\
	}							\
}								\
END {								\
	if (busy > 1) {						\
		collision += ($3 - start_collision);		\
	}							\
	printf "Total time     =  %13.9f (%d)\n", ($3 - first_send), total;	\
	printf "Idle time      =  %13.9f     \n", idle;				\
	printf "Collision time =  %13.9f (%d)\n", collision, collisions;	\
}'