amidi: add timestamp option for dump

Added -T / --timestamp option (with parameter "realtime", "monotonic" or "raw") which prints
a timestamp before each received message when using the --dump mode.

Fixes: https://github.com/alsa-project/alsa-utils/pull/108
Signed-off-by: Folkert van Heusden <mail@vanheusden.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

amidi/amidi.c

@@ -36,11 +36,13 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <alsa/asoundlib.h>
+#include <time.h>
 #include "aconfig.h"
 #include "version.h"
 
 #define NSEC_PER_SEC 1000000000L
 
+static int do_print_timestamp = 0;
 static int do_device_list, do_rawmidi_list;
 static char *port_name = "default";
 static char *send_file_name;
@@ -80,6 +82,10 @@ static void usage(void)
 		"-r, --receive=file              write received data into a file\n"
 		"-S, --send-hex=\"...\"            send hexadecimal bytes\n"
 		"-d, --dump                      print received data as hexadecimal bytes\n"
+		"-T, --timestamp=...             adds a timestamp in front of each dumped message\n"
+		"                realtime\n"
+		"                monotonic\n"
+		"                raw\n"
 		"-t, --timeout=seconds           exits when no data has been received\n"
 		"                                for the specified duration\n"
 		"-a, --active-sensing            include active sensing bytes\n"
@@ -356,7 +362,7 @@ static void parse_data(void)
 /*
  * prints MIDI commands, formatting them nicely
  */
-static void print_byte(unsigned char byte)
+static void print_byte(unsigned char byte, struct timespec *ts)
 {
 	static enum {
 		STATE_UNKNOWN,
@@ -426,7 +432,18 @@ static void print_byte(unsigned char byte)
 		if (running_status)
 			fputs("\n  ", stdout);
 	}
-	printf("%c%02X", newline ? '\n' : ' ', byte);
+
+	if (newline) {
+		printf("\n");
+
+		/* Nanoseconds does not make a lot of sense for serial MIDI (the
+		 * 31250 bps one) but I'm not sure about MIDI over USB.
+		 */
+		if (do_print_timestamp)
+			printf("%lld.%.9ld) ", (long long)ts->tv_sec, ts->tv_nsec);
+	}
+
+	printf("%02X", byte);
 }
 
 static void sig_handler(int dummy)
@@ -454,7 +471,7 @@ static void add_send_hex_data(const char *str)
 
 int main(int argc, char *argv[])
 {
-	static const char short_options[] = "hVlLp:s:r:S::dt:aci:";
+	static const char short_options[] = "hVlLp:s:r:S::dt:aci:T:";
 	static const struct option long_options[] = {
 		{"help", 0, NULL, 'h'},
 		{"version", 0, NULL, 'V'},
@@ -465,6 +482,7 @@ int main(int argc, char *argv[])
 		{"receive", 1, NULL, 'r'},
 		{"send-hex", 2, NULL, 'S'},
 		{"dump", 0, NULL, 'd'},
+		{"timestamp", 1, NULL, 'T'},
 		{"timeout", 1, NULL, 't'},
 		{"active-sensing", 0, NULL, 'a'},
 		{"clock", 0, NULL, 'c'},
@@ -475,6 +493,7 @@ int main(int argc, char *argv[])
 	int ignore_active_sensing = 1;
 	int ignore_clock = 1;
 	int do_send_hex = 0;
+	clockid_t cid = CLOCK_REALTIME;
 	struct itimerspec itimerspec = { .it_interval = { 0, 0 } };
 
 	while ((c = getopt_long(argc, argv, short_options,
@@ -509,6 +528,19 @@ int main(int argc, char *argv[])
 		case 'd':
 			dump = 1;
 			break;
+		case 'T':
+			do_print_timestamp = 1;
+			if (optarg == NULL)
+				error("Clock type missing");
+			else if (strcasecmp(optarg, "realtime") == 0)
+				cid = CLOCK_REALTIME;
+			else if (strcasecmp(optarg, "monotonic") == 0)
+				cid = CLOCK_MONOTONIC;
+			else if (strcasecmp(optarg, "raw") == 0)
+				cid = CLOCK_MONOTONIC_RAW;
+			else
+				error("Clock type not known");
+			break;
 		case 't':
 			if (optarg)
 				timeout = atof(optarg);
@@ -611,6 +643,7 @@ int main(int argc, char *argv[])
 	}
 
 	if (inputp) {
+		int need_timestamp = 0;
 		int read = 0;
 		int npfds;
 		struct pollfd *pfds;
@@ -644,10 +677,12 @@ int main(int argc, char *argv[])
 				goto _exit;
 			}
 		}
+
 		for (;;) {
 			unsigned char buf[256];
 			int i, length;
 			unsigned short revents;
+			struct timespec ts;
 
 			err = poll(pfds, npfds, -1);
 			if (stop || (err < 0 && errno == EINTR))
@@ -657,6 +692,11 @@ int main(int argc, char *argv[])
 				break;
 			}
 
+			if (clock_gettime(cid, &ts) < 0) {
+				error("clock_getres (%d) failed: %s", cid, strerror(errno));
+				break;
+			}
+
 			err = snd_rawmidi_poll_descriptors_revents(input, &pfds[1], npfds - 1, &revents);
 			if (err < 0) {
 				error("cannot get poll events: %s", snd_strerror(errno));
@@ -688,14 +728,12 @@ int main(int argc, char *argv[])
 				continue;
 			read += length;
 
-			if (receive_file != -1) {
+			if (receive_file != -1)
-				ssize_t wlength = write(receive_file, buf, length);
+				write(receive_file, buf, length);
-				if (wlength != length)
-					error("write error: %s", wlength < 0 ? strerror(errno) : "short");
-			}
 			if (dump) {
 				for (i = 0; i < length; ++i)
-					print_byte(buf[i]);
+					print_byte(buf[i], &ts);
+
 				fflush(stdout);
 			}