encoder_step.hpp

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// sbl/hw/components/input/encoder_step.hpp — Encoder pulse-to-step converter
//
// Many rotary encoders (e.g., EC11) produce multiple electrical pulses
// per physical detent. EncoderStep accumulates raw pulses and emits
// ±1 step only when a full detent boundary is crossed.
//
// The residual is preserved across calls, so no pulses are lost.
//
// Usage:
//   sbl::components::input::EncoderStep enc(4);  // EC11: 4 pulses/detent
//   // In your control loop:
//   int8_t step = enc.process(encoder.delta());
//   if (step != 0) { /* one detent click: +1 or -1 */ }
 
#ifndef SBL_HW_COMPONENTS_INPUT_ENCODER_STEP_HPP_
#define SBL_HW_COMPONENTS_INPUT_ENCODER_STEP_HPP_
 
#include <cstdint>
 
namespace sbl {
namespace components {
namespace input {
 
class EncoderStep {
public:
    /// @param divisor Pulses per detent (e.g., 4 for EC11). Must be >= 1.
    explicit EncoderStep(int8_t divisor = 4)
        : divisor_(divisor < 1 ? 1 : divisor) {}
 
    /// Feed raw encoder delta, returns step (-1, 0, or +1).
    int8_t process(int32_t raw_delta) {
        accum_ += static_cast<int8_t>(raw_delta);
        int8_t step = 0;
        if (accum_ >= divisor_) {
            step = 1;
            accum_ -= divisor_;
        } else if (accum_ <= -divisor_) {
            step = -1;
            accum_ += divisor_;
        }
        return step;
    }
 
    /// Current accumulator value.
    int8_t accumulator() const { return accum_; }
 
    /// Reset accumulator to zero.
    void reset() { accum_ = 0; }
 
private:
    int8_t divisor_;
    int8_t accum_ = 0;
};
 
} // namespace input
} // namespace components
} // namespace sbl
 
#endif // SBL_HW_COMPONENTS_INPUT_ENCODER_STEP_HPP_