From a4ff8b18d8c02b566ec1e203f983fc111408a752 Mon Sep 17 00:00:00 2001
From: Simon Howard
Date: Mon, 28 Mar 2011 21:36:00 +0000
Subject: Fix OPL MIDI playback when using an empty .mus / .mid file (thanks
 Alexandre Xavier).

Subversion-branch: /trunk/chocolate-doom
Subversion-revision: 2313
---
 NEWS             | 2 ++
 src/i_oplmusic.c | 9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index b76917f2..c0163f8c 100644
--- a/NEWS
+++ b/NEWS
@@ -41,6 +41,8 @@
        Xavier).
      * Weapon cycling from the shotgun to the chaingun in Doom 1 now
        works properly (thanks Alexandre Xavier).
+     * MIDI playback that locked up when using an empty MUS / MIDI
+       file (thanks Alexandre Xavier).
 
     libtextscreen:
      * It is now possible to type a '+' in input boxes (thanks
diff --git a/src/i_oplmusic.c b/src/i_oplmusic.c
index e8d65d6d..97ba0783 100644
--- a/src/i_oplmusic.c
+++ b/src/i_oplmusic.c
@@ -1080,7 +1080,7 @@ static void ScheduleTrack(opl_track_data_t *track);
 
 // Restart a song from the beginning.
 
-static void RestartSong(void)
+static void RestartSong(void *unused)
 {
     unsigned int i;
 
@@ -1118,10 +1118,15 @@ static void TrackTimerCallback(void *arg)
         --running_tracks;
 
         // When all tracks have finished, restart the song.
+        // Don't restart the song immediately, but wait for 5ms
+        // before triggering a restart.  Otherwise it is possible
+        // to construct an empty MIDI file that causes the game
+        // to lock up in an infinite loop. (5ms should be short
+        // enough not to be noticeable by the listener).
 
         if (running_tracks <= 0 && song_looping)
         {
-            RestartSong();
+            OPL_SetCallback(5, RestartSong, NULL);
         }
 
         return;
-- 
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