3 files changed, 61 insertions, 7 deletions

diff --git a/engines/glk/glk_api.cpp b/engines/glk/glk_api.cpp
index 08dce8cd12..f638ea3a0d 100644
--- a/engines/glk/glk_api.cpp
+++ b/engines/glk/glk_api.cpp
@@ -1022,7 +1022,11 @@ void GlkAPI::glk_schannel_stop(schanid_t chan) {
 }
 
 void GlkAPI::glk_schannel_set_volume(schanid_t chan, glui32 vol) {
-	// TODO
+	if (chan) {
+		chan->setVolume(vol);
+	} else {
+		warning("schannel_set_volume: invalid ref");
+	}
 }
 
 void GlkAPI::glk_sound_load_hint(glui32 snd, glui32 flag) {
@@ -1041,16 +1045,28 @@ glui32 GlkAPI::glk_schannel_play_multi(schanid_t *chanarray, glui32 chancount,
 }
 
 void GlkAPI::glk_schannel_pause(schanid_t chan) {
-	// TODO
+	if (chan) {
+		chan->pause();
+	} else {
+		warning("schannel_pause: invalid ref");
+	}
 }
 
 void GlkAPI::glk_schannel_unpause(schanid_t chan) {
-	// TODO
+	if (chan) {
+		chan->unpause();
+	} else {
+		warning("schannel_unpause: invalid ref");
+	}
 }
 
 void GlkAPI::glk_schannel_set_volume_ext(schanid_t chan, glui32 vol,
                                       glui32 duration, glui32 notify) {
-	// TODO
+	if (chan) {
+		chan->setVolume(vol, duration, notify);
+	} else {
+		warning("schannel_set_volume_ext: invalid ref");
+	}
 }
 
 void GlkAPI::glk_set_hyperlink(glui32 linkval) {
diff --git a/engines/glk/sound.cpp b/engines/glk/sound.cpp
index 02fb7f9253..0e3fbf48ee 100644
--- a/engines/glk/sound.cpp
+++ b/engines/glk/sound.cpp
@@ -144,10 +144,29 @@ void SoundChannel::stop() {
 }
 
 void SoundChannel::poll() {
-	if (!g_vm->_mixer->isSoundHandleActive(_handle) && _notify != 0)
-		g_vm->_events->store(evtype_SoundNotify, 0,
-			_soundNum, _notify);
+	if (!g_vm->_mixer->isSoundHandleActive(_handle) && _notify != 0) {
+		glui32 notify = _notify;
+		_notify = 0;
+		g_vm->_events->store(evtype_SoundNotify, nullptr, _soundNum, notify);
+	}
+}
+
+void SoundChannel::setVolume(uint volume, uint duration, uint notify) {
+	uint newVol = volume * 255 / 0x10000;
+	g_vm->_mixer->setChannelVolume(_handle, newVol);
+
+	if (notify) {
+		warning("TODO: Gradual volume change");
+		g_vm->_events->store(evtype_VolumeNotify, nullptr, 0, notify);	
+	}
+}
+
+void SoundChannel::pause() {
+	g_vm->_mixer->pauseHandle(_handle, true);
+}
 
+void SoundChannel::unpause() {
+	g_vm->_mixer->pauseHandle(_handle, false);
 }
 
 } // End of namespace Glk
diff --git a/engines/glk/sound.h b/engines/glk/sound.h
index 514a5f6ad2..9635302b8d 100644
--- a/engines/glk/sound.h
+++ b/engines/glk/sound.h
@@ -68,6 +68,25 @@ public:
 	 * Poll for whether a playing sound was finished
 	 */
 	void poll();
+
+	/**
+	 * Change the volume
+	 * @param volume		Volume from 0 (silence) to 0x10000 (full volume)
+	 * @param duration		Optional duration for a gradual volume change
+	 * @param notify		If non-zero, triggers a evtype_VolumeNotify when
+	 *						the volume change duration finishes
+	 */
+	void setVolume(uint volume, uint duration = 0, uint notify = 0);
+
+	/**
+	 * Pause playback
+	 */
+	void pause();
+
+	/**
+	 * Unpause playback
+	 */
+	void unpause();
 };
 typedef SoundChannel *schanid_t;