vca.hpp

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// sbl/widgets/proc/vca.hpp — Voltage Controlled Amplifier (Audio Stack — Widgets)
//
// Stateless amplitude modulation. Multiplies audio by a control signal
// (envelope) or a constant gain.
//
// Usage:
//   sbl::widgets::proc::Vca::process(audio, envelope, frames);  // modulation
//   sbl::widgets::proc::Vca::apply_gain(audio, gain, frames);   // constant
 
#pragma once
 
#include <cstdint>
 
namespace sbl::widgets::proc {
 
class Vca {
public:
    /// @note All public methods are ISR-safe — bounded computation, no I/O.
 
    /**
     * @brief Multiply audio by per-sample control signal (envelope)
     *
     * Control signal is float [0.0, 1.0] matching Envelope output.
     *
     * @param audio Audio buffer (modified in-place, float)
     * @param control Control buffer (envelope output, [0.0, 1.0])
     * @param frames Number of samples
     */
    static void process(float* audio, const float* control, uint16_t frames) {
        for (uint16_t i = 0; i < frames; ++i) {
            audio[i] *= control[i];
        }
    }
 
    /**
     * @brief Apply constant gain
     *
     * @param audio Audio buffer (modified in-place, float)
     * @param gain Gain factor (0.0 = silence, 1.0 = unity)
     * @param frames Number of samples
     */
    static void apply_gain(float* audio, float gain, uint16_t frames) {
        for (uint16_t i = 0; i < frames; ++i) {
            audio[i] *= gain;
        }
    }
};
 
} // namespace sbl::widgets::proc