bool Player_AD::parseCommand() {
uint command = _musicData[_curOffset++];
if (command == 0xFF) {
// META EVENT
// Get the command number.
command = _musicData[_curOffset++];
if (command == 47) {
// End of track
if (_loopFlag) {
// In case the track is looping jump to the start.
_curOffset = _musicLoopStart;
_nextEventTimer = 0;
} else {
// Otherwise completely stop playback.
stopMusic();
}
return true;
} else if (command == 88) {
// This is proposedly a debug information insertion. The CMS
// player code handles this differently, but is still using
// the same resources...
_curOffset += 5;
} else if (command == 81) {
// Change tempo. This is used exclusively in Loom.
const uint timing = _musicData[_curOffset + 2] | (_musicData[_curOffset + 1] << 8);
_musicTicks = 0x73000 / timing;
command = _musicData[_curOffset++];
_curOffset += command;
} else {
// In case an unknown meta event occurs just skip over the
// data by using the length supplied.
command = _musicData[_curOffset++];
_curOffset += command;
}
} else {
if (command >= 0x90) {
// NOTE ON
// Extract the channel number and save it in command.
command -= 0x90;
const uint instrOffset = _instrumentOffset[command];
if (instrOffset) {
if (_musicData[instrOffset + 13] != 0) {
setupRhythm(_musicData[instrOffset + 13], instrOffset);
} else {
// Priority 256 makes sure we always prefer music
// channels over SFX channels.
int channel = allocateHWChannel(256);
if (channel != -1) {
setupChannel(channel, _musicData + instrOffset);
_voiceChannels[channel].lastEvent = command + 0x90;
_voiceChannels[channel].frequency = _musicData[_curOffset];
setupFrequency(channel, _musicData[_curOffset]);
}
}
}
} else {
// NOTE OFF
const uint note = _musicData[_curOffset];
command += 0x10;
// Find the output channel which plays the note.
uint channel = 0xFF;
for (int i = 0; i < ARRAYSIZE(_voiceChannels); ++i) {
if (_voiceChannels[i].frequency == note && _voiceChannels[i].lastEvent == command) {
channel = i;
break;
}
}
if (channel != 0xFF) {
// In case a output channel playing the note was found,
// stop it.
noteOff(channel);
} else {
// In case there is no such note this will disable the
// rhythm instrument played on the channel.
command -= 0x90;
const uint instrOffset = _instrumentOffset[command];
if (instrOffset && _musicData[instrOffset + 13] != 0) {
const uint rhythmInstr = _musicData[instrOffset + 13];
if (rhythmInstr < 6) {
_mdvdrState &= _mdvdrTable[rhythmInstr] ^ 0xFF;
writeReg(0xBD, _mdvdrState);
}
}
}
}
_curOffset += 2;
}
return false;
}
void MusicPlayer::callback() {
if (!_isPlaying)
return;
_musicTimer += _musicTicks;
if (_musicTimer < _timerLimit)
return;
_musicTimer -= _timerLimit;
--_nextEventTimer;
if (_nextEventTimer)
return;
while (true) {
uint8_t command = _file.at(_curOffset++);
if (command == 0xFF) {
command = _file.at(_curOffset++);
if (command == 47) {
// End of track
_isPlaying = false;
return;
} else if (command == 88) {
// This is proposedly a debug information insertion. The CMS
// player code handles this differently, but is still using
// the same resources...
_curOffset += 5;
} else if (command == 81) {
uint16_t timing = _file.at(_curOffset + 2) | (_file.at(_curOffset + 1) << 8);
_musicTicks = 0x73000 / timing;
command = _file.at(_curOffset++);
_curOffset += command;
} else {
command = _file.at(_curOffset++);
_curOffset += command;
}
} else {
if (command >= 0x90) {
command -= 0x90;
const uint16_t instrOffset = _instrumentOffset[command];
if (instrOffset) {
if (_file.at(instrOffset + 13) != 0) {
setupRhythm(_file[instrOffset + 13], instrOffset);
} else {
uint8_t channel = findFreeChannel();
if (channel != 0xFF) {
noteOff(channel);
setupChannel(channel, instrOffset);
_channelLastEvent[channel] = command + 0x90;
_channelFrequency[channel] = _file.at(_curOffset);
setupFrequency(channel, _file[_curOffset]);
}
}
}
} else {
const uint8_t note = _file.at(_curOffset);
command += 0x10;
uint8_t channel = 0xFF;
for (uint8_t i = 0; i < _voiceChannels; ++i) {
if (_channelFrequency[i] == note && _channelLastEvent[i] == command) {
channel = i;
break;
}
}
if (channel != 0xFF) {
noteOff(channel);
} else {
command -= 0x90;
const uint16_t instrOffset = _instrumentOffset[command];
if (instrOffset && _file.at(instrOffset + 13) != 0) {
const uint8_t rhythmInstr = _file[instrOffset + 13];
//if (rhythmInstr >= 6)
// throw std::range_error("rhythmInstr >= 6");
if (rhythmInstr < 6) {
_mdvdrState &= _mdvdrTable[rhythmInstr] ^ 0xFF;
writeReg(0xBD, _mdvdrState);
}
}
}
}
_curOffset += 2;
}
if (_file.at(_curOffset) != 0)
break;
++_curOffset;
}
_nextEventTimer = _file.at(_curOffset++);
if (_nextEventTimer & 0x80) {
_nextEventTimer -= 0x80;
_nextEventTimer <<= 7;
_nextEventTimer |= _file.at(_curOffset++);
}
_nextEventTimer >>= _isLoom ? 2 : 1;
if (!_nextEventTimer)
_nextEventTimer = 1;
}