129 lines
3.8 KiB
C++
129 lines
3.8 KiB
C++
#ifndef SYNTH_ENGINE_H
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#define SYNTH_ENGINE_H
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#include <stdint.h>
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#include <mutex>
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/**
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* @class SynthEngine
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* @brief A portable, platform-agnostic synthesizer engine.
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*
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* This class contains the core digital signal processing (DSP) logic.
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* It has no dependencies on any specific hardware, OS, or audio API.
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* It works by filling a provided buffer with 16-bit signed audio samples.
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*
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* The oscillator uses a 32-bit unsigned integer as a phase accumulator,
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* which is highly efficient and avoids floating-point math in the audio loop,
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* making it ideal for the RP2040.
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*/
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class SynthEngine {
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public:
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enum Waveform {
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SAWTOOTH,
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SQUARE,
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SINE
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};
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/**
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* @brief Constructs the synthesizer engine.
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* @param sampleRate The audio sample rate in Hz (e.g., 44100).
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*/
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~SynthEngine();
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SynthEngine(uint32_t sampleRate);
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/**
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* @brief Fills a buffer with audio samples. This is the main audio callback.
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* @param buffer Pointer to the output buffer to be filled.
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* @param numFrames The number of audio frames (samples) to generate.
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*/
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void process(int16_t* buffer, uint32_t numFrames);
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/**
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* @brief Sets the frequency of the oscillator.
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* @param freq The frequency in Hz.
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*/
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void setFrequency(float freq);
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/**
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* @brief Sets the output volume.
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* @param vol Volume from 0.0 (silent) to 1.0 (full).
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*/
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void setVolume(float vol);
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/**
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* @brief Sets the oscillator's waveform.
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* @param form The waveform to use.
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*/
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void setWaveform(Waveform form);
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/**
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* @brief Opens or closes the sound gate.
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* @param isOpen True to produce sound, false for silence.
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*/
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void setGate(bool isOpen);
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/**
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* @brief Gets the current frequency of the oscillator.
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* @return The frequency in Hz.
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*/
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float getFrequency() const;
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/**
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* @brief Configures the ADSR envelope.
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* @param attack Attack time in seconds.
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* @param decay Decay time in seconds.
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* @param sustain Sustain level (0.0 to 1.0).
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* @param release Release time in seconds.
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*/
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void setADSR(float attack, float decay, float sustain, float release);
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/**
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* @brief Configures the filters.
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* @param lpCutoff Low-pass cutoff frequency in Hz.
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* @param hpCutoff High-pass cutoff frequency in Hz.
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*/
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void setFilter(float lpCutoff, float hpCutoff);
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// --- Grid Synth ---
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struct GridCell {
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enum Type { EMPTY, FIXED_OSCILLATOR, INPUT_OSCILLATOR, WAVETABLE, NOISE, LFO, FORK, WIRE, LPF, HPF, VCA, BITCRUSHER, DISTORTION, GLITCH, OPERATOR, DELAY, REVERB, SINK };
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enum Op { OP_ADD, OP_MUL, OP_SUB, OP_DIV, OP_MIN, OP_MAX };
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Type type = EMPTY;
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float param = 0.5f; // 0.0 to 1.0
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int rotation = 0; // 0:N, 1:E, 2:S, 3:W (Output direction)
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float value = 0.0f; // Current output sample
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float phase = 0.0f; // For Oscillator, Noise state
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float* buffer = nullptr; // For Delay
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uint32_t buffer_size = 0; // For Delay
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uint32_t write_idx = 0; // For Delay
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};
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GridCell grid[5][8];
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std::mutex gridMutex;
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// Helper to process one sample step of the grid
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float processGridStep();
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private:
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uint32_t _sampleRate;
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uint32_t _phase; // Phase accumulator for the oscillator.
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uint32_t _increment; // Phase increment per sample, determines frequency.
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float _volume;
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Waveform _waveform;
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bool _isGateOpen;
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// ADSR State
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enum EnvState { ENV_IDLE, ENV_ATTACK, ENV_DECAY, ENV_SUSTAIN, ENV_RELEASE };
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EnvState _envState;
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float _envLevel;
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float _attackInc, _decayDec, _sustainLevel, _releaseDec;
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// Filter State
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float _lpAlpha;
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float _hpAlpha;
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float _lpVal;
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float _hpVal;
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};
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#endif // SYNTH_ENGINE_H
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