More Euphony/YM2612 instrument layering and polyphony

fixes. Aside from variations in the instrument timbre,
the output from ScummVM now seems to match up with the
output from UNZ (MAME YM2612 emulator).

svn-id: r10672

1 files changed, 12 insertions, 14 deletions

diff --git a/scumm/midiparser_eup.cpp b/scumm/midiparser_eup.cpp
index eeca9fbb6d..c8c6f95fdc 100644
--- a/scumm/midiparser_eup.cpp
+++ b/scumm/midiparser_eup.cpp
@@ -33,7 +33,7 @@ namespace Scumm {
 class MidiParser_EUP : public MidiParser {
 protected:
 	byte _instruments[6][50]; // Two extra bytes for SysEx ID and channel #
-	byte _channel_instr[16];
+	byte *_instr_to_channel;
 	struct {
 		byte *enable;
 		int8 *channel;
@@ -71,20 +71,21 @@ void MidiParser_EUP::parseNextEvent (EventInfo &info) {
 	// program changes to get a reasonable "one-size-
 	// fits-all" sound until we actually support the
 	// FM synthesis capabilities of FM Towns.
-	for (; _presend < 32; ++_presend) {
-		if (_channel_instr[_presend >> 1] == 0xFF) continue;
+	for (; _presend < 12; ++_presend) {
+		if (_instr_to_channel[_presend>>1] >= 16)
+			continue;
 		info.start = pos;
 		info.delta = 0;
 		if (_presend & 1) {
-			info.event = 0xB0;
-			info.basic.param1 = 7;
-			info.basic.param2 = 127;
-		} else {
-			byte *data = &_instruments[_channel_instr[_presend >> 1]][0];
-			data[1] = _presend >> 1;
+			byte *data = &_instruments[_presend>>1][0];
+			data[1] = _instr_to_channel[_presend>>1];
 			info.event = 0xF0;
 			info.ext.data = data;
 			info.length = 48;
+		} else {
+			info.event = 0xB0 | (_presend >> 1);
+			info.basic.param1 = 121;
+			info.basic.param2 = 0;
 		}
 		++_presend;
 		return;
@@ -186,11 +187,8 @@ bool MidiParser_EUP::loadMusic (byte *data, uint32 size) {
 	pos += 32;
 
 	pos += 8; // Unknown bytes
-	for (i = 0; i < 16; ++i)
-		_channel_instr[i] = 0xFF;
-	for (i = 0; i < 6; ++i)
-		_channel_instr[pos[i]] = i;
-	pos += 6; // Instrument-to-channel mapping (not supported yet)
+	_instr_to_channel = pos; // Instrument-to-channel mapping
+	pos += 6;
 	pos += 4; // Skip the music size for now.
 	pos++;    // Unknown byte
 	byte tempo = *pos++;