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Makes first attempt to reintroduce full-melodic output.

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This commit is contained in:
Thomas Harte 2020-05-05 00:16:45 -04:00
parent 386a7ca442
commit c9fb5721cd
2 changed files with 76 additions and 1 deletions
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72
Components/OPL2/OPLL.cpp
View File

@ -211,5 +211,75 @@ void OPLL::set_sample_volume_range(std::int16_t range) {
}
void OPLL::get_samples(std::size_t number_of_samples, std::int16_t *target) {
// TODO.
// Both the OPLL and the OPL2 divide the input clock by 72 to get the base tick frequency;
// unlike the OPL2 the OPLL time-divides the output for 'mixing'.
const int update_period = 72 / audio_divider_;
const int channel_output_period = 4 / audio_divider_;
// TODO: the conditional below is terrible. Fix.
while(number_of_samples--) {
if(!audio_offset_) update_all_channels();
*target = output_levels_[audio_offset_ / channel_output_period];
++target;
audio_offset_ = (audio_offset_ + 1) % update_period;
}
}
void OPLL::update_all_channels() {
oscillator_.update();
// Update all phase generators. That's guaranteed.
for(int c = 0; c < 18; ++c) {
phase_generators_[c].update(oscillator_);
}
// Update the ADSR envelopes that are guaranteed to be melodic.
for(int c = 0; c < 6; ++c) {
envelope_generators_[c + 0].update(oscillator_);
envelope_generators_[c + 9].update(oscillator_);
}
#define VOLUME(x) int16_t(((x) * total_volume_) >> 12)
if(rhythm_mode_enabled_) {
// TODO!
} else {
for(int c = 6; c < 9; ++c) {
envelope_generators_[c + 0].update(oscillator_);
envelope_generators_[c + 9].update(oscillator_);
}
// All melodic. Fairly easy.
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] = 0;
output_levels_[3] = VOLUME(melodic_output(0));
output_levels_[4] = VOLUME(melodic_output(1));
output_levels_[5] = VOLUME(melodic_output(2));
output_levels_[9] = VOLUME(melodic_output(3));
output_levels_[10] = VOLUME(melodic_output(4));
output_levels_[11] = VOLUME(melodic_output(5));
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
// TODO: batch updates of the LFSR.
}
int OPLL::melodic_output(int channel) {
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;
return WaveformGenerator<period_precision>::wave(channels_[channel].carrier_waveform, phase_generators_[channel].scaled_phase(), modulation).level();
}

5
Components/OPL2/OPLL.hpp
View File

@ -38,8 +38,13 @@ class OPLL: public OPLBase<OPLL> {
void write_register(uint8_t address, uint8_t value);
int audio_divider_ = 0;
int audio_offset_ = 0;
std::atomic<int> total_volume_;
void update_all_channels();
int melodic_output(int channel);
int16_t output_levels_[18];
static constexpr int period_precision = 9;
static constexpr int envelope_precision = 9;