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In principle fully implements rhythm mode.

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This commit is contained in:
Thomas Harte 2020-05-07 23:38:51 -04:00
parent e12dc5d894
commit 5219a86a41
2 changed files with 128 additions and 22 deletions
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121
Components/OPL2/OPLL.cpp
View File

@ -32,6 +32,36 @@ OPLL::OPLL(Concurrency::DeferringAsyncTaskQueue &task_queue, int audio_divider,
for(int c = 0; c < 9; ++c) {
install_instrument(c);
}
// Setup the rhythm envelope generators.
// Treat the bass exactly as if it were a melodic channel.
rhythm_envelope_generators_[BassCarrier].set_should_damp([this] {
// Propagate attack mode to the modulator, and reset both phases.
rhythm_envelope_generators_[BassModulator].set_key_on(true);
phase_generators_[6 + 0].reset();
phase_generators_[6 + 9].reset();
});
// Crib the proper rhythm envelope generator settings by installing
// the rhythm instruments and copying them over.
rhythm_mode_enabled_ = true;
install_instrument(6);
install_instrument(7);
install_instrument(8);
rhythm_envelope_generators_[BassCarrier] = envelope_generators_[6];
rhythm_envelope_generators_[BassModulator] = envelope_generators_[6 + 9];
rhythm_envelope_generators_[HighHat] = envelope_generators_[7];
rhythm_envelope_generators_[Cymbal] = envelope_generators_[8];
rhythm_envelope_generators_[TomTom] = envelope_generators_[8 + 9];
rhythm_envelope_generators_[Snare] = envelope_generators_[7 + 9];
// Return to ordinary default mode.
rhythm_mode_enabled_ = false;
install_instrument(6);
install_instrument(7);
install_instrument(8);
}
// MARK: - Machine-facing programmatic input.
@ -67,11 +97,17 @@ void OPLL::write_register(uint8_t address, uint8_t value) {
install_instrument(7);
install_instrument(8);
}
rhythm_generators_[0].set_key_on(value & 0x01);
rhythm_generators_[1].set_key_on(value & 0x02);
rhythm_generators_[2].set_key_on(value & 0x04);
rhythm_generators_[3].set_key_on(value & 0x08);
rhythm_generators_[4].set_key_on(value & 0x10);
rhythm_envelope_generators_[0].set_key_on(value & 0x01);
rhythm_envelope_generators_[1].set_key_on(value & 0x02);
rhythm_envelope_generators_[2].set_key_on(value & 0x04);
rhythm_envelope_generators_[3].set_key_on(value & 0x08);
if(value & 0x10) {
rhythm_envelope_generators_[4].set_key_on(true);
} else {
rhythm_envelope_generators_[4].set_key_on(false);
rhythm_envelope_generators_[5].set_key_on(false);
}
return;
}
@ -269,10 +305,8 @@ void OPLL::update_all_channels() {
if(rhythm_mode_enabled_) {
// Advance the rhythm envelope generators.
// TODO: these need to be properly seeded.
for(int c = 0; c < 5; ++c) {
oscillator_.update_lfsr();
rhythm_generators_[c].update(oscillator_);
for(int c = 0; c < 6; ++c) {
rhythm_envelope_generators_[c].update(oscillator_);
}
// Fill in the melodic channels.
@ -284,12 +318,29 @@ void OPLL::update_all_channels() {
output_levels_[10] = VOLUME(melodic_output(4));
output_levels_[11] = VOLUME(melodic_output(5));
// TODO: drum noises. Also subject to proper channel population.
// Bass drum, which is a regular FM effect.
output_levels_[2] = output_levels_[15] = VOLUME(bass_drum());
oscillator_.update_lfsr();
output_levels_[0] = output_levels_[1] = output_levels_[2] =
output_levels_[6] = output_levels_[7] = output_levels_[8] =
output_levels_[12] = output_levels_[13] = output_levels_[14] =
output_levels_[15] = output_levels_[16] = output_levels_[17] = 0;
// Tom tom, which is a single operator.
output_levels_[1] = output_levels_[14] = VOLUME(tom_tom());
oscillator_.update_lfsr();
// Snare.
output_levels_[6] = output_levels_[16] = VOLUME(snare_drum());
oscillator_.update_lfsr();
// Cymbal.
output_levels_[7] = output_levels_[17] = VOLUME(cymbal());
oscillator_.update_lfsr();
// High-hat.
output_levels_[0] = output_levels_[13] = VOLUME(high_hat());
oscillator_.update_lfsr();
// Unutilised slots.
output_levels_[8] = output_levels_[12] = 0;
oscillator_.update_lfsr();
} else {
for(int c = 6; c < 9; ++c) {
envelope_generators_[c + 0].update(oscillator_);
@ -312,8 +363,6 @@ void OPLL::update_all_channels() {
output_levels_[15] = VOLUME(melodic_output(6));
output_levels_[16] = VOLUME(melodic_output(7));
output_levels_[17] = VOLUME(melodic_output(8));
// TODO: advance LFSR.
}
#undef VOLUME
@ -322,9 +371,9 @@ void OPLL::update_all_channels() {
// TODO: modulator feedback.
}
// TODO: verify attenuation scales pervasively below.
int OPLL::melodic_output(int channel) {
// TODO: verify attenuation scales.
auto modulation = WaveformGenerator<period_precision>::wave(channels_[channel].modulator_waveform, phase_generators_[channel + 9].phase());
modulation += envelope_generators_[channel + 9].attenuation() + (channels_[channel].modulator_attenuation << 5) + key_level_scalers_[channel + 9].attenuation();
@ -332,3 +381,41 @@ int OPLL::melodic_output(int channel) {
carrier += envelope_generators_[channel].attenuation() + (channels_[channel].attenuation << 7) + key_level_scalers_[channel].attenuation();
return carrier.level();
}
int OPLL::bass_drum() {
// Use modulator 6 and carrier 6, attenuated as per the bass-specific envelope generators and the attenuation level for channel 6.
auto modulation = WaveformGenerator<period_precision>::wave(Waveform::Sine, phase_generators_[6 + 9].phase());
modulation += envelope_generators_[RhythmIndices::BassModulator].attenuation();
auto carrier = WaveformGenerator<period_precision>::wave(Waveform::Sine, phase_generators_[6].scaled_phase(), modulation);
carrier += envelope_generators_[RhythmIndices::BassCarrier].attenuation() + (channels_[6].attenuation << 7);
return carrier.level();
}
int OPLL::tom_tom() {
// Use modulator 8 and the 'instrument' selection for channel 8 as an attenuation.
auto tom_tom = WaveformGenerator<period_precision>::wave(Waveform::Sine, phase_generators_[8 + 9].phase());
tom_tom += envelope_generators_[RhythmIndices::TomTom].attenuation() + (channels_[8].instrument << 7);
return tom_tom.level();
}
int OPLL::snare_drum() {
// Use modulator 7 and the carrier attenuation level for channel 7.
LogSign snare = WaveformGenerator<period_precision>::snare(oscillator_, phase_generators_[7 + 9].phase());
snare += channels_[7].attenuation << 7;
return snare.level();
}
int OPLL::cymbal() {
// Use modulator 7, carrier 8 and the attenuation level for channel 8.
LogSign cymbal = WaveformGenerator<period_precision>::cymbal(phase_generators_[8].phase(), phase_generators_[7 + 9].phase());
cymbal += channels_[8].attenuation << 7;
return cymbal.level();
}
int OPLL::high_hat() {
// Use the 'instrument' selection for channel 7 as an attenuation.
LogSign high_hat = WaveformGenerator<period_precision>::high_hat(oscillator_, phase_generators_[8].phase(), phase_generators_[7 + 9].phase());
high_hat += channels_[7].instrument << 7;
return high_hat.level();
}

29
Components/OPL2/OPLL.hpp
View File

@ -41,21 +41,40 @@ class OPLL: public OPLBase<OPLL> {
int audio_offset_ = 0;
std::atomic<int> total_volume_;
void update_all_channels();
int melodic_output(int channel);
int16_t output_levels_[18];
void update_all_channels();
int melodic_output(int channel);
int bass_drum();
int tom_tom();
int snare_drum();
int cymbal();
int high_hat();
static constexpr int period_precision = 9;
static constexpr int envelope_precision = 9;
// Standard melodic phase and envelope generators.
// Standard melodic phase and envelope generators;
//
// These are assigned as:
//
// [x], 0 <= x < 9 = carrier for channel x;
// [x+9] = modulator for channel x.
//
PhaseGenerator<period_precision> phase_generators_[18];
EnvelopeGenerator<envelope_precision, period_precision> envelope_generators_[18];
KeyLevelScaler<period_precision> key_level_scalers_[18];
// Dedicated rhythm envelope generators and attenuations.
EnvelopeGenerator<envelope_precision, period_precision> rhythm_generators_[5];
int rhythm_attenuations_[5];
EnvelopeGenerator<envelope_precision, period_precision> rhythm_envelope_generators_[6];
enum RhythmIndices {
HighHat = 0,
Cymbal = 1,
TomTom = 2,
Snare = 3,
BassCarrier = 4,
BassModulator = 5
};
// Channel specifications.
struct Channel {