95 lines
2.0 KiB
C++
95 lines
2.0 KiB
C++
#pragma once
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#include <cmath>
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namespace trnr {
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class tx_sineosc {
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public:
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bool phase_reset;
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tx_sineosc(double _samplerate)
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: samplerate { _samplerate }
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, phase_resolution { 16.f }
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, phase { 0. }
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, history { 0. }
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, phase_reset { false }
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{
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}
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void set_phase_resolution(float res) {
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phase_resolution = powf(2, res);
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}
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float process_sample(bool trigger, float frequency, float phase_modulation = 0.f) {
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if (trigger && phase_reset) {
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phase = 0.0;
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}
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float lookup_phase = phase + phase_modulation;
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wrap(lookup_phase);
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phase += frequency / samplerate;
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wrap(phase);
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redux(lookup_phase);
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float output = sine(lookup_phase * 4096.);
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filter(output);
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return output;
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}
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void set_samplerate(double _samplerate) {
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this->samplerate = _samplerate;
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}
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private:
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double samplerate;
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float phase_resolution;
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float phase;
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float history;
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float sine(float x) {
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// x is scaled 0<=x<4096
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const float a = -0.40319426317E-08;
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const float b = 0.21683205691E+03;
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const float c = 0.28463350538E-04;
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const float d = -0.30774648337E-02;
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float y;
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bool negate = false;
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if (x > 2048) {
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negate = true;
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x -= 2048;
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}
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if (x > 1024)
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x = 2048 - x;
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y = (a + x) / (b + c * x * x) + d * x;
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if (negate)
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return (float)(-y);
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else
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return (float)y;
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}
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float wrap(float& phase) {
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while (phase < 0.)
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phase += 1.;
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while (phase >= 1.)
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phase -= 1.;
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return phase;
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}
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float filter(float& value) {
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value = 0.5 * (value + history);
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history = value;
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return value;
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}
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float redux(float& value)
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{
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value = static_cast<int>(value * phase_resolution) / phase_resolution;
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return value;
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}
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};
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} |