X-Git-Url: https://rtime.felk.cvut.cz/gitweb/sojka/can-utils.git/blobdiff_plain/5655d53acb2d7427d5d80a29c49db47fcbac76a3..HEAD:/canbusload.c

diff --git a/canbusload.c b/canbusload.c
index 36f3423..a5fb553 100644
--- a/canbusload.c
+++ b/canbusload.c
@@ -1,7 +1,3 @@
-/*
- *  $Id$
- */
-
 /*
  * canbusload.c
  *
@@ -41,7 +37,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  *
- * Send feedback to <socketcan-users@lists.berlios.de>
+ * Send feedback to <linux-can@vger.kernel.org>
  *
  */
 
@@ -88,6 +84,7 @@ static unsigned char redraw;
 static unsigned char timestamp;
 static unsigned char color;
 static unsigned char bargraph;
+static unsigned char ignore_bitstuffing;
 static char *prg;
 
 void print_usage(char *prg)
@@ -98,20 +95,22 @@ void print_usage(char *prg)
 	fprintf(stderr, "         -c (colorize lines)\n");
 	fprintf(stderr, "         -b (show bargraph in %d%% resolution)\n", PERCENTRES);
 	fprintf(stderr, "         -r (redraw the terminal - similar to top)\n");
+	fprintf(stderr, "         -i (ignore bitstuffing estimation in bandwith calculation)\n");
 	fprintf(stderr, "\n");
 	fprintf(stderr, "Up to %d CAN interfaces with mandatory bitrate can be specified on the \n", MAXSOCK);
 	fprintf(stderr, "commandline in the form: <ifname>@<bitrate>\n\n");
 	fprintf(stderr, "The bitrate is mandatory as it is needed to know the CAN bus bitrate to\n");
 	fprintf(stderr, "calcultate the bus load percentage based on the received CAN frames.\n");
+	fprintf(stderr, "Due to the bitstuffing estimation the calculated busload may exceed 100%%.\n");
 	fprintf(stderr, "For each given interface the data is presented in one line which contains:\n\n");
 	fprintf(stderr, "(interface) (received CAN frames) (used bits total) (used bits for payload)\n");
 	fprintf(stderr, "\nExample:\n");
 	fprintf(stderr, "\nuser$> canbusload can0@100000 can1@500000 can2@500000 can3@500000 -r -t -b -c\n\n");
 	fprintf(stderr, "%s 2008-05-27 15:18:49\n", prg);
-	fprintf(stderr, " can0@100000  805  74491  36656  74%%  |XXXXXXXXXXXXXX......|\n");
-	fprintf(stderr, " can1@500000  796  75140  37728  15%%  |XXX.................|\n");
-	fprintf(stderr, " can2@500000    0      0      0   0%%  |....................|\n");
-	fprintf(stderr, " can3@500000   47   4633   2424   0%%  |....................|\n");
+	fprintf(stderr, " can0@100000   805   74491  36656  74%% |XXXXXXXXXXXXXX......|\n");
+	fprintf(stderr, " can1@500000   796   75140  37728  15%% |XXX.................|\n");
+	fprintf(stderr, " can2@500000     0       0      0   0%% |....................|\n");
+	fprintf(stderr, " can3@500000    47    4633   2424   0%% |....................|\n");
 	fprintf(stderr, "\n");
 }
 
@@ -162,7 +161,7 @@ void printstats(int signo)
 		else
 			percent = 0;
 
-		printf(" %*s@%-*d %4d %6d %6d %3d%%",
+		printf(" %*s@%-*d %5d %7d %6d %3d%%",
 		       max_devname_len, stat[i].devname,
 		       max_bitrate_len, stat[i].bitrate,
 		       stat[i].recv_frames,
@@ -172,7 +171,10 @@ void printstats(int signo)
 
 		if (bargraph) {
 
-			printf("  |");
+			printf(" |");
+
+			if (percent > 100)
+				percent = 100;
 
 			for (j=0; j < NUMBAR; j++){
 				if (j < percent/PERCENTRES)
@@ -195,6 +197,7 @@ void printstats(int signo)
 	}
 
 	printf("\n");
+	fflush(stdout);
 
 	alarm(1);
 }
@@ -220,7 +223,7 @@ int main(int argc, char **argv)
 
 	prg = basename(argv[0]);
 
-	while ((opt = getopt(argc, argv, "rtbch?")) != -1) {
+	while ((opt = getopt(argc, argv, "rtbcih?")) != -1) {
 		switch (opt) {
 		case 'r':
 			redraw = 1;
@@ -238,6 +241,10 @@ int main(int argc, char **argv)
 			color = 1;
 			break;
 
+		case 'i':
+			ignore_bitstuffing = 1;
+			break;
+
 		default:
 			print_usage(prg);
 			exit(1);
@@ -365,11 +372,32 @@ int main(int argc, char **argv)
 
 				stat[i].recv_frames++;
 				stat[i].recv_bits_payload += frame.can_dlc*8;
-				stat[i].recv_bits_total += frame.can_dlc*8;
-				if (frame.can_id & CAN_EFF_FLAG)
-					stat[i].recv_bits_total += 67;
-				else
-					stat[i].recv_bits_total += 47;
+
+				/*
+				 * Following Ken Tindells *worst* case calculation for stuff-bits
+				 * (see "Guaranteeing Message Latencies on Controller Area Network" 1st ICC'94)
+				 * the needed bits on the wire can be calculated as:
+				 *
+				 * (34 + 8n)/5 + 47 + 8n for SFF frames (11 bit CAN-ID) => (269 + 48n)/5 
+				 * (54 + 8n)/5 + 67 + 8n for EFF frames (29 bit CAN-ID) => (389 + 48n)/5 
+				 *
+				 * while 'n' is the data length code (number of payload bytes)
+				 *
+				 */
+
+				if (ignore_bitstuffing) {
+					/* calculation without bitstuffing */
+					if (frame.can_id & CAN_EFF_FLAG)
+						stat[i].recv_bits_total += 67 + frame.can_dlc*8;
+					else
+						stat[i].recv_bits_total += 47 + frame.can_dlc*8;
+				} else {
+					/* needed bits including estimated worst case stuff bits */
+					if (frame.can_id & CAN_EFF_FLAG)
+						stat[i].recv_bits_total += (389 + frame.can_dlc*48)/5;
+					else
+						stat[i].recv_bits_total += (269 + frame.can_dlc*48)/5;
+				}
 			}
 		}
 	}