- Added Gez's HMI/XMI division fixes, and partially the XMI tempo fix (not currently used).

SVN r3377 (trunk)

src/sound/i_musicinterns.h

@@ -637,6 +637,7 @@ protected:
 
 	int FindXMIDforms(const BYTE *chunk, int len, TrackInfo *songs) const;
 	void FoundXMID(const BYTE *chunk, int len, TrackInfo *song) const;
+	void ScanForTempo(const TrackInfo *song);
 	bool SetMIDISubsong(int subsong);
 	void DoInitialSetup();
 	void DoRestart();

src/sound/music_hmi_midiout.cpp

@@ -1,5 +1,5 @@
 /*
-** music_midi_midiout.cpp
+** music_hmi_midiout.cpp
 ** Code to let ZDoom play HMI MIDI music through the MIDI streaming API.
 **
 **---------------------------------------------------------------------------
@@ -54,7 +54,7 @@
 	}
 
 // In song header
-#define HMI_DIVISION_OFFSET			0xD2
+#define HMI_DIVISION_OFFSET			0xD4
 #define HMI_TRACK_COUNT_OFFSET		0xE4
 #define HMI_TRACK_DIR_PTR_OFFSET	0xE8
 
@@ -202,7 +202,10 @@ void HMISong::SetupForHMI(int len)
 	}
 
 	// The division is the number of pulses per quarter note (PPQN).
-	Division = GetShort(MusHeader + HMI_DIVISION_OFFSET);
+	// HMI files have two values here, a full value and a quarter value. Some games, 
+	// notably Quarantines, have identical values for some reason, so it's safer to
+	// use the quarter value and multiply it by four than to trust the full value.
+	Division = GetShort(MusHeader + HMI_DIVISION_OFFSET) << 2;
 	InitialTempo = 4000000;
 
 	Tracks = new TrackInfo[NumTracks + 1];

src/sound/music_xmi_midiout.cpp

@@ -134,14 +134,16 @@ XMISong::XMISong (FILE *file, BYTE *musiccache, int len, EMidiDevice type)
 	{
 		return;
 	}
+	// The division is the number of pulses per quarter note (PPQN).
+	// It is set by a specific MIDI event, but just in case these aren't used,
+	// set a default value. Specs indicate it should be 120.
+	Division = 120;
 	Songs = new TrackInfo[NumSongs];
 	memset(Songs, 0, sizeof(*Songs) * NumSongs);
 	FindXMIDforms(MusHeader, len, Songs);
 	CurrSong = Songs;
 	DPrintf("XMI song count: %d\n", NumSongs);
-
+	DPrintf("Divisions: %d\n", Division);
-	// The division is the number of pulses per quarter note (PPQN).
-	Division = 60;
 }
 
 //==========================================================================
@@ -198,6 +200,8 @@ int XMISong::FindXMIDforms(const BYTE *chunk, int len, TrackInfo *songs) const
 		// IFF chunks are padded to even byte boundaries to avoid
 		// unaligned reads on 68k processors.
 		p += 8 + chunklen + (chunklen & 1);
+		// Avoid crashes from corrupt chunks which indicate a negative size.
+		if (chunklen < 0) p = len;
 	}
 	return count;
 }
@@ -233,6 +237,37 @@ void XMISong::FoundXMID(const BYTE *chunk, int len, TrackInfo *song) const
 	}
 }
 
+//==========================================================================
+//
+// XMISong :: ScanForTempo
+//
+// Look through events chunk to find one that sets the tempo.
+//
+//==========================================================================
+
+void XMISong::ScanForTempo(const TrackInfo *song)
+{
+	const BYTE *chunk = song->EventChunk;
+
+	for (size_t q = 0; q < song->EventLen - 3; )
+	{
+		int r = q;
+		int evmark = chunk[r];
+		int evtype = chunk[r + 1];
+		int evlen  = chunk[r + 2];
+		//  Is it a tempo event? If so, length should be 3.
+		if (evmark == MIDI_META && evtype == MIDI_META_TEMPO && evlen == 3)
+		{
+			// Tempo is given in microseconds per quarter notes, so for a base of
+			// 120 per second, we have to divide by a million a multiply by 120 to
+			// get the PPQN. This is simplified by 40 to manipulate smaller values.
+			Tempo = (chunk[r + 3] << 16) | (chunk[r + 4] << 8) | chunk[r + 5];
+			Division = Tempo * 3 / 25000;
+		}
+		q += 3 + evlen;
+	}
+}
+
 //==========================================================================
 //
 // XMISong :: SetMIDISubsong
@@ -304,7 +339,7 @@ bool XMISong::CheckDone()
 //
 // XMISong :: MakeEvents
 //
-// Copies MIDI events from the SMF and puts them into a MIDI stream
+// Copies MIDI events from the XMI and puts them into a MIDI stream
 // buffer. Returns the new position in the buffer.
 //
 //==========================================================================
@@ -542,6 +577,7 @@ DWORD *XMISong::SendCommand (DWORD *events, EventSource due, DWORD delay)
 					events[1] = 0;
 					events[2] = (MEVT_TEMPO << 24) | Tempo;
 					events += 3;
+					Division = Tempo * 3 / 25000;
 					break;
 				}
 				track->EventP += len;