commit 0f4e0bbca959251f256a285d829b6517430e7401
from: Sven M. Hallberg <pesco@khjk.org>
date: Thu Nov 09 19:11:07 2023 UTC

clean up return latency code in cwstop

commit - 02b03fabec05c9e959d5b89c8a5b06c5e4c1d330
commit + 0f4e0bbca959251f256a285d829b6517430e7401
blob - f5becb2c828ecec2e3c1779ead6c88ab362c3f27
blob + c4104284c0719a3b60be1879dd6c8dd397bb8b80
--- cw.c
+++ cw.c
@@ -325,6 +325,9 @@ cwstart()
 int
 cwstop(void)
 {
+	struct timespec t, dt;
+	int ms;
+
 	if (!sio_stop(hdl))
 		errx(1, "sio_stop failed");
 
@@ -333,14 +336,14 @@ cwstop(void)
 	 * between playback finishing and the return of the function. This
 	 * value can be negative, meaning that we actually returned earlier
 	 * than playback will finish.
+	 *
+	 * Since we cannot directly determine the point in time when playback
+	 * finished (or will finish), we take the current time since the
+	 * _start_ of playback minus the total playback time, as determined by
+	 * the number of frames written.
 	 */
-	struct timespec tnow, dt;
-	int playms, nowms;
-
-	clock_gettime(CLOCK_MONOTONIC, &tnow);
-	timespecsub(&tnow, &tplay, &dt);
-	nowms = dt.tv_sec * 1000 + dt.tv_nsec / 1000000;
-	playms = writ * 1000 / par.rate;
-
-	return nowms - playms;
+	clock_gettime(CLOCK_MONOTONIC, &t);
+	timespecsub(&t, &tplay, &dt);
+	ms = dt.tv_sec * 1000 + dt.tv_nsec / 1000000;
+	return ms - writ * 1000 / par.rate;
 }