opl: Tweak voice replacement algorithm.

Prefer replacing a second voice before a voice from a higher-
numbered channel. This resolves some issues with the MAP01 music,
as noted in comments on #468; it may not be Vanilla behavior in
terms of code but seems to better match it based on observation,
and makes logical sense.

Also adjust code to fit to the 80 column limit.

1 files changed, 12 insertions, 7 deletions

diff --git a/src/i_oplmusic.c b/src/i_oplmusic.c
index c02f1941..a5910056 100644
--- a/src/i_oplmusic.c
+++ b/src/i_oplmusic.c
@@ -353,7 +353,8 @@ static boolean LoadInstrumentTable(void)
 
     main_instrs = (genmidi_instr_t *) (lump + strlen(GENMIDI_HEADER));
     percussion_instrs = main_instrs + GENMIDI_NUM_INSTRS;
-    main_instr_names = (char (*)[32]) (percussion_instrs + GENMIDI_NUM_PERCUSSION);
+    main_instr_names =
+        (char (*)[32]) (percussion_instrs + GENMIDI_NUM_PERCUSSION);
     percussion_names = main_instr_names + GENMIDI_NUM_INSTRS;
 
     return true;
@@ -529,7 +530,8 @@ static void SetVoiceVolume(opl_voice_t *voice, unsigned int volume)
     midi_volume = 2 * (volume_mapping_table[(voice->channel->volume
                   * current_music_volume) / 127] + 1);
 
-    full_volume = (volume_mapping_table[voice->note_volume] * midi_volume) >> 9;
+    full_volume = (volume_mapping_table[voice->note_volume] * midi_volume)
+                >> 9;
 
     // The volume value to use in the register:
     car_volume = 0x3f - full_volume;
@@ -545,7 +547,8 @@ static void SetVoiceVolume(opl_voice_t *voice, unsigned int volume)
         // If we are using non-modulated feedback mode, we must set the
         // volume for both voices.
 
-        if ((opl_voice->feedback & 0x01) != 0 && opl_voice->modulator.level != 0x3f)
+        if ((opl_voice->feedback & 0x01) != 0
+         && opl_voice->modulator.level != 0x3f)
         {
             mod_volume = 0x3f - opl_voice->modulator.level;
             if (mod_volume >= car_volume)
@@ -553,7 +556,8 @@ static void SetVoiceVolume(opl_voice_t *voice, unsigned int volume)
                 mod_volume = car_volume;
             }
             OPL_WriteRegister(OPL_REGS_LEVEL + voice->op1,
-                              mod_volume | (opl_voice->modulator.scale & 0xc0));
+                              mod_volume |
+                              (opl_voice->modulator.scale & 0xc0));
         }
     }
 }
@@ -668,7 +672,7 @@ static void KeyOffEvent(opl_track_data_t *track, midi_event_t *event)
 // passed to the function is the channel for the new note to be
 // played.
 
-static void ReplaceExistingVoice()
+static void ReplaceExistingVoice(void)
 {
     opl_voice_t *rover;
     opl_voice_t *result;
@@ -685,8 +689,9 @@ static void ReplaceExistingVoice()
 
     for (rover = voice_alloced_list; rover != NULL; rover = rover->next)
     {
-        if (rover->current_instr_voice != 0
-         || rover->channel >= result->channel)
+        if (rover->current_instr_voice > result->current_instr_voice
+         || (rover->current_instr_voice == result->current_instr_voice
+          && rover->channel >= result->channel))
         {
             result = rover;
         }