[scripts] AggCheck: -n prints transmitters

When called with -n, owlps-aggcheck now prints the transmitter of each
request as the first column.

scripts/owlps-aggcheck.pl

@@ -45,7 +45,10 @@ Print signal strength distribution in CSV format.
 =item B<-n>
 
 Print per-request statistics in CSV format, as well as the total number of
-packets received by each capture point.
+packets received by each capture point. Please note that this display is ordered
+by timestamp (unlike the default display which respects the order of the lines
+in the input file); this might not correspond to the actual order of
+transmission if the devices' clocks are not synchronised.
 
 =item B<-v>
 
@@ -89,6 +92,11 @@ use constant PREFIX_FIELDS => 9;
 # Line number
 my $line_nb = 0;
 
+# Association between timestamp and transmitter of each request
+# key = timestamp
+# value = transmitter's MAC address
+my %transmitters;
+
 # Structure that holds the global count of packets
 # key = timestamp
 # value = dictionary {key = CP's MAC address
@@ -231,6 +239,7 @@ while (<>) {
     }
 
     # Save the values for the stats
+    $transmitters{$timestamp} = $mac_trx;
     $global_stats{$timestamp} = {%present_cps};
 
     # Print the number of packets for each CP and count the number of CPs
@@ -257,13 +266,13 @@ if ($print_stats) {
 
     # Print the header line
     my @cps_names = sort keys %global_present_cps;
-    print "Timestamp";
+    print "Transmitter;Timestamp";
     print ";$_" foreach (@cps_names);
     print "\n";
 
     # Print the requests
     foreach my $timestamp (sort keys %global_stats) {
-        print "$timestamp";
+        print "$transmitters{$timestamp};$timestamp";
         my $present_cps = $global_stats{$timestamp};
         # Print the CPs in the same order as in the header and count the totals
         foreach my $mac (@cps_names) {
@@ -275,7 +284,7 @@ if ($print_stats) {
     }
 
     # Print the totals
-    print "Total";
+    print "Total;";
     print ";$total_nb_pkts{$_}" foreach (@cps_names);
     print "\n";
 }