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https://github.com/TomHarte/CLK.git
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Adds KeyLevelScaler, implements EnvelopeGenerator, adds reset
to PhaseGenerator.
This commit is contained in:
parent
9d2691d1d2
commit
1ff5ea0a6e
@ -29,17 +29,60 @@ namespace OPL {
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this is largely for logical conformity with the phase generator that necessarily has to
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this is largely for logical conformity with the phase generator that necessarily has to
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apply vibrato.
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apply vibrato.
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*/
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*/
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template <int precision> class EnvelopeGenerator {
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template <int envelope_precision, int period_precision> class EnvelopeGenerator {
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public:
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public:
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/*!
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/*!
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Advances the envelope generator a single step, given the current state of the low-frequency oscillator, @c oscillator.
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Advances the envelope generator a single step, given the current state of the low-frequency oscillator, @c oscillator.
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*/
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*/
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void update(const LowFrequencyOscillator &oscillator);
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void update(const LowFrequencyOscillator &oscillator) {
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// Apply tremolo, which is fairly easy.
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tremolo_ = tremolo_enable_ * oscillator.tremolo << 4;
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// Something something something...
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const int key_scaling_rate = key_scale_rate_ >> key_scale_rate_shift_;
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switch(phase_) {
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case Phase::Damp:
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update_decay(oscillator, 12);
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if(attenuation_ == 511) {
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will_attack_();
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phase_ = Phase::Attack;
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}
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break;
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case Phase::Attack:
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update_attack(oscillator, attack_rate_ + key_scaling_rate);
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// Two possible terminating conditions: (i) the attack rate is 15; (ii) full volume has been reached.
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if((attack_rate_ + key_scaling_rate) > 60 || attenuation_ <= 0) {
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attenuation_ = 0;
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phase_ = Phase::Decay;
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}
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break;
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case Phase::Decay:
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update_decay(oscillator, decay_rate_ + key_scaling_rate);
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if(attenuation_ >= sustain_level_) {
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attenuation_ = sustain_level_;
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phase_ = use_sustain_level_ ? Phase::Sustain : Phase::Release;
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}
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break;
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case Phase::Sustain:
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// Nothing to do.
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break;
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case Phase::Release:
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update_decay(oscillator, release_rate_ + key_scaling_rate);
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break;
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}
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}
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/*!
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/*!
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@returns The current attenuation from this envelope generator.
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@returns The current attenuation from this envelope generator.
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*/
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*/
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int attenuation() const;
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int attenuation() const {
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return attenuation_ + tremolo_;
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}
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/*!
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/*!
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Enables or disables damping on this envelope generator. If damping is enabled then this envelope generator will
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Enables or disables damping on this envelope generator. If damping is enabled then this envelope generator will
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@ -48,63 +91,165 @@ template <int precision> class EnvelopeGenerator {
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@param will_attack Supply a will_attack callback to enable damping mode; supply nullopt to disable damping mode.
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@param will_attack Supply a will_attack callback to enable damping mode; supply nullopt to disable damping mode.
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*/
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*/
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void set_should_damp(const std::optional<std::function<void(void)>> &will_attack);
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void set_should_damp(const std::optional<std::function<void(void)>> &will_attack) {
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will_attack_ = will_attack;
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}
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/*!
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/*!
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Sets the current state of the key-on input.
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Sets the current state of the key-on input.
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*/
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*/
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void set_key_on(bool);
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void set_key_on(bool key_on) {
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// Do nothing if this is not a leading or trailing edge.
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if(key_on == key_on_) return;
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key_on_ = key_on;
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// Always transition to release upon a key off.
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if(!key_on_) {
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phase_ = Phase::Release;
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return;
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}
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// On key on: if this is an envelope generator with damping, and damping is required,
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// schedule that. If damping is not required, announce a pending attack now and
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// transition to attack.
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if(will_attack_) {
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if(attenuation_ != 511) {
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phase_ = Phase::Damp;
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return;
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}
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will_attack_();
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}
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phase_ = Phase::Attack;
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}
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/*!
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/*!
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Sets the attack rate, which should be in the range 0–15.
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Sets the attack rate, which should be in the range 0–15.
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*/
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*/
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void set_attack_rate(int);
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void set_attack_rate(int rate) {
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attack_rate_ = rate << 2;
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}
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/*!
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/*!
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Sets the decay rate, which should be in the range 0–15.
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Sets the decay rate, which should be in the range 0–15.
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*/
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*/
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void set_decay_rate(int);
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void set_decay_rate(int rate) {
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decay_rate_ = rate << 2;
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}
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/*!
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/*!
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Sets the release rate, which should be in the range 0–15.
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Sets the release rate, which should be in the range 0–15.
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*/
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*/
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void set_release_rate(int);
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void set_release_rate(int rate) {
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release_rate_ = rate << 2;
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}
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/*!
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/*!
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Sets the sustain level, which should be in the range 0–15.
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Sets the sustain level, which should be in the range 0–15.
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*/
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*/
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void set_sustain_level(int);
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void set_sustain_level(int level) {
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sustain_level_ = level << 3;
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// TODO: verify the shift level here. Especially re: precision.
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}
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/*!
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/*!
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Enables or disables use of the sustain level. If this is disabled, the envelope proceeds
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Enables or disables use of the sustain level. If this is disabled, the envelope proceeds
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directly from decay to release.
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directly from decay to release.
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*/
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*/
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void set_use_sustain_level(bool);
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void set_use_sustain_level(bool use) {
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use_sustain_level_ = use;
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}
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/*!
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/*!
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Enables or disables key-rate scaling.
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Enables or disables key-rate scaling.
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*/
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*/
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void set_key_rate_scaling_enabled(bool enabled);
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void set_key_scaling_rate_enabled(bool enabled) {
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key_scale_rate_shift_ = int(enabled) * 2;
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}
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/*!
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/*!
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Enables or disables application of the low-frequency oscillator's tremolo.
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Enables or disables application of the low-frequency oscillator's tremolo.
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*/
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*/
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void set_tremolo_enabled(bool enabled);
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void set_tremolo_enabled(bool enabled) {
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tremolo_enable_ = int(enabled);
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}
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/*!
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/*!
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Sets the current period associated with the channel that owns this envelope generator;
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Sets the current period associated with the channel that owns this envelope generator;
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this is used to select a key scaling rate if key-rate scaling is enabled.
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this is used to select a key scaling rate if key-rate scaling is enabled.
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*/
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*/
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void set_period(int period, int octave);
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void set_period(int period, int octave) {
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key_scale_rate_ = (octave << 1) | (period >> (period_precision - 1));
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}
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private:
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private:
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enum class ADSRPhase {
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enum class Phase {
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Attack, Decay, Sustain, Release, Damp
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Attack, Decay, Sustain, Release, Damp
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} adsr_phase_ = ADSRPhase::Attack;
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} phase_ = Phase::Attack;
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int adsr_attenuation_ = 511;
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int attenuation_ = 511, tremolo_ = 0;
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bool key_on_ = false;
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bool key_on_ = false;
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std::optional<std::function<void(void)>> will_attack_;
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std::optional<std::function<void(void)>> will_attack_;
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int key_scale_rate_ = 0;
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int key_scale_rate_shift_ = 0;
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int tremolo_enable_ = 0;
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int attack_rate_ = 0;
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int decay_rate_ = 0;
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int release_rate_ = 0;
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int sustain_level_ = 0;
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bool use_sustain_level_ = false;
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void update_attack(const LowFrequencyOscillator &oscillator, int rate) {
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// Rules:
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//
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// An attack rate of '13' has 32 samples in the attack phase; a rate of '12' has the same 32 steps, but spread out over 64 samples, etc.
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// An attack rate of '14' uses a divide by four instead of two.
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// 15 is instantaneous.
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if(rate >= 56) {
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attenuation_ -= (attenuation_ >> 2) - 1;
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} else {
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const int sample_length = 1 << (14 - (rate >> 2)); // TODO: don't throw away KSR bits.
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if(!(oscillator.counter & (sample_length - 1))) {
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attenuation_ -= (attenuation_ >> 3) - 1;
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}
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}
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}
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void update_decay(const LowFrequencyOscillator &oscillator, int rate) {
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// Rules:
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//
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// (relative to a 511 scale)
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//
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// A rate of 0 is no decay at all.
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// A rate of 1 means increase 4 per cycle.
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// A rate of 2 means increase 2 per cycle.
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// A rate of 3 means increase 1 per cycle.
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// A rate of 4 means increase 1 every other cycle.
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// A rate of 5 means increase once every fourth cycle.
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// etc.
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// eighth, sixteenth, 32nd, 64th, 128th, 256th, 512th, 1024th, 2048th, 4096th, 8192th
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if(rate) {
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// TODO: don't throw away low two bits of the rate.
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switch(rate >> 2) {
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case 1: attenuation_ += 32; break;
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case 2: attenuation_ += 16; break;
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default: {
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const int sample_length = 1 << ((rate >> 2) - 4);
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if(!(oscillator.counter & (sample_length - 1))) {
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attenuation_ += 8;
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}
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} break;
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}
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// Clamp to the proper range.
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attenuation_ = std::min(attenuation_, 511);
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}
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}
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};
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};
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}
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}
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58
Components/OPL2/Implementation/KeyLevelScaler.hpp
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58
Components/OPL2/Implementation/KeyLevelScaler.hpp
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@ -0,0 +1,58 @@
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//
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// KeyLevelScaler.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 02/05/2020.
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// Copyright © 2020 Thomas Harte. All rights reserved.
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//
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#ifndef KeyLevelScaler_h
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#define KeyLevelScaler_h
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namespace Yamaha {
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namespace OPL {
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template <int frequency_precision> class KeyLevelScaler {
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public:
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/*!
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Sets the current period associated with the channel that owns this envelope generator;
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this is used to select a key scaling rate if key-rate scaling is enabled.
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*/
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void set_period(int period, int octave) {
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constexpr int key_level_scales[16] = {0, 48, 64, 74, 80, 86, 90, 94, 96, 100, 102, 104, 106, 108, 110, 112};
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constexpr int masks[2] = {~0, 0};
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// A two's complement assumption is embedded below; the use of masks relies
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// on the sign bit to clamp to zero.
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level_ = key_level_scales[period >> (frequency_precision - 4)];
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level_ -= 16 * (octave ^ 7);
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level_ &= masks[(key_scale_rate_ >> ((sizeof(int) * 8) - 1)) & 1];
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}
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/*!
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Enables or disables key-rate scaling.
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*/
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void set_key_scaling_level(int level) {
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// '7' is just a number large enough to render all possible scaling coefficients as 0.
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constexpr int key_level_scale_shifts[4] = {7, 1, 2, 0};
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shift_ = key_level_scale_shifts[level];
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}
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/*!
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@returns The current attenuation level due to key-level scaling.
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*/
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int attenuation() const {
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return level_ >> shift_;
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}
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private:
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int level_ = 0;
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int shift_ = 0;
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};
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}
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}
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#endif /* KeyLevelScaler_h */
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@ -38,7 +38,7 @@ template <int precision> class PhaseGenerator {
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const int vibrato = (top_freq >> vibrato_shifts[oscillator.vibrato]) * vibrato_signs[oscillator.vibrato >> 2] * enable_vibrato_;
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const int vibrato = (top_freq >> vibrato_shifts[oscillator.vibrato]) * vibrato_signs[oscillator.vibrato >> 2] * enable_vibrato_;
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// Apply phase update with vibrato from the low-frequency oscillator.
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// Apply phase update with vibrato from the low-frequency oscillator.
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raw_phase_ += multiple_ * (period_ + vibrato) << octave_;
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phase_ += multiple_ * (period_ + vibrato) << octave_;
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}
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}
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@ -48,7 +48,7 @@ template <int precision> class PhaseGenerator {
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int phase() const {
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int phase() const {
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// My table if multipliers is multiplied by two, so shift by one more
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// My table if multipliers is multiplied by two, so shift by one more
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// than the stated precision.
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// than the stated precision.
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return raw_phase_ >> precision_shift;
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return phase_ >> precision_shift;
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}
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}
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/*!
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/*!
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@ -85,21 +85,22 @@ template <int precision> class PhaseGenerator {
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enable_vibrato_ = int(enabled);
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enable_vibrato_ = int(enabled);
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}
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}
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enum class Waveform {
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/*!
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Sine, HalfSine, AbsSine, PulseSine
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Resets the current phase.
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};
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*/
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void reset() {
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phase_ = 0;
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}
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private:
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private:
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static constexpr int precision_shift = 1 + precision;
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static constexpr int precision_shift = 1 + precision;
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int raw_phase_ = 0;
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int phase_ = 0;
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int multiple_ = 0;
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int multiple_ = 0;
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int period_ = 0;
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int period_ = 0;
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int octave_ = 0;
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int octave_ = 0;
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int enable_vibrato_ = 0;
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int enable_vibrato_ = 0;
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Waveform waveform_ = Waveform::Sine;
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};
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};
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}
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}
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@ -1153,6 +1153,7 @@
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4B61908F24526E640013F202 /* LowFrequencyOscillator.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = LowFrequencyOscillator.hpp; sourceTree = "<group>"; };
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4B61908F24526E640013F202 /* LowFrequencyOscillator.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = LowFrequencyOscillator.hpp; sourceTree = "<group>"; };
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4B619092245BC1000013F202 /* PhaseGenerator.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = PhaseGenerator.hpp; sourceTree = "<group>"; };
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4B619092245BC1000013F202 /* PhaseGenerator.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = PhaseGenerator.hpp; sourceTree = "<group>"; };
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4B622AE4222E0AD5008B59F2 /* DisplayMetrics.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; name = DisplayMetrics.hpp; path = ../../Outputs/DisplayMetrics.hpp; sourceTree = "<group>"; };
|
4B622AE4222E0AD5008B59F2 /* DisplayMetrics.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; name = DisplayMetrics.hpp; path = ../../Outputs/DisplayMetrics.hpp; sourceTree = "<group>"; };
|
||||||
4B643F381D77AD1900D431D6 /* CSStaticAnalyser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = CSStaticAnalyser.h; path = StaticAnalyser/CSStaticAnalyser.h; sourceTree = "<group>"; };
|
4B643F381D77AD1900D431D6 /* CSStaticAnalyser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = CSStaticAnalyser.h; path = StaticAnalyser/CSStaticAnalyser.h; sourceTree = "<group>"; };
|
||||||
@ -3536,6 +3537,7 @@
|
|||||||
4B61908F24526E640013F202 /* LowFrequencyOscillator.hpp */,
|
4B61908F24526E640013F202 /* LowFrequencyOscillator.hpp */,
|
||||||
4B619092245BC1000013F202 /* PhaseGenerator.hpp */,
|
4B619092245BC1000013F202 /* PhaseGenerator.hpp */,
|
||||||
4B619093245CD63E0013F202 /* EnvelopeGenerator.hpp */,
|
4B619093245CD63E0013F202 /* EnvelopeGenerator.hpp */,
|
||||||
|
4B619094245E73B90013F202 /* KeyLevelScaler.hpp */,
|
||||||
);
|
);
|
||||||
path = Implementation;
|
path = Implementation;
|
||||||
sourceTree = "<group>";
|
sourceTree = "<group>";
|
||||||
|
Loading…
Reference in New Issue
Block a user