Emulator

synth_engine.cpp

@@ -0,0 +1,35 @@
+#include "synth_engine.h"
+
+SynthEngine::SynthEngine(uint32_t sampleRate)
+    : _sampleRate(sampleRate),
+      _phase(0),
+      _increment(0)
+{
+    // Initialize with a default frequency
+    setFrequency(440.0f);
+}
+
+void SynthEngine::setFrequency(float freq) {
+    // Calculate the phase increment for a given frequency.
+    // The phase accumulator is a 32-bit unsigned integer (0 to 2^32 - 1).
+    // One full cycle of the accumulator represents one cycle of the waveform.
+    // increment = (frequency * 2^32) / sampleRate
+    // We use a 64-bit intermediate calculation to prevent overflow.
+    _increment = static_cast<uint32_t>((static_cast<uint64_t>(freq) << 32) / _sampleRate);
+}
+
+void SynthEngine::process(int16_t* buffer, uint32_t numFrames) {
+    for (uint32_t i = 0; i < numFrames; ++i) {
+        // 1. Advance the phase. Integer overflow automatically wraps it,
+        //    which is exactly what we want for a continuous oscillator.
+        _phase += _increment;
+
+        // 2. Generate the sample. For a sawtooth wave, the sample value is
+        //    directly proportional to the phase. We take the top 16 bits
+        //    of the 32-bit phase accumulator to get a signed 16-bit sample.
+        int16_t sample = static_cast<int16_t>(_phase >> 16);
+
+        // 3. Write the sample to the buffer.
+        buffer[i] = sample;
+    }
+}