Emulator

synth_engine.h

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+#ifndef SYNTH_ENGINE_H
+#define SYNTH_ENGINE_H
+
+#include <stdint.h>
+
+/**
+ * @class SynthEngine
+ * @brief A portable, platform-agnostic synthesizer engine.
+ *
+ * This class contains the core digital signal processing (DSP) logic.
+ * It has no dependencies on any specific hardware, OS, or audio API.
+ * It works by filling a provided buffer with 16-bit signed audio samples.
+ *
+ * The oscillator uses a 32-bit unsigned integer as a phase accumulator,
+ * which is highly efficient and avoids floating-point math in the audio loop,
+ * making it ideal for the RP2040.
+ */
+class SynthEngine {
+public:
+    /**
+     * @brief Constructs the synthesizer engine.
+     * @param sampleRate The audio sample rate in Hz (e.g., 44100).
+     */
+    SynthEngine(uint32_t sampleRate);
+
+    /**
+     * @brief Fills a buffer with audio samples. This is the main audio callback.
+     * @param buffer Pointer to the output buffer to be filled.
+     * @param numFrames The number of audio frames (samples) to generate.
+     */
+    void process(int16_t* buffer, uint32_t numFrames);
+
+    /**
+     * @brief Sets the frequency of the oscillator.
+     * @param freq The frequency in Hz.
+     */
+    void setFrequency(float freq);
+
+private:
+    uint32_t _sampleRate;
+    uint32_t _phase;      // Phase accumulator for the oscillator.
+    uint32_t _increment;  // Phase increment per sample, determines frequency.
+};
+
+#endif // SYNTH_ENGINE_H