M src/gb/audio.c → src/gb/audio.c

@@ -121,6 +121,9 @@ audio->ch1.sweepStep = audio->ch1.time;
 		if (!audio->ch1.control.length) {
 			audio->ch1.control.length = 64;
 		}
+		if (audio->playingCh1 && audio->ch1.shift) {
+			audio->playingCh1 = _updateSweep(&audio->ch1);
+		}
 		audio->nextEvent = 0;
 	}
 }
@@ -360,7 +363,7 @@ audio->ch1.sample = sample * audio->ch1.envelope.currentVolume;
 						}
 					}
 
-					if ((frame & 3) == 2) {
+					if (audio->ch1.sweepStep && (frame & 3) == 2) {
 						--audio->ch1.sweepStep;
 						if (audio->ch1.sweepStep == 0) {
 							audio->playingCh1 = _updateSweep(&audio->ch1);