dc_blocker.hpp

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#pragma once
 
#include <pulp/signal/denormal.hpp>
 
namespace pulp::signal {

template<typename T = float>
class DcBlocker {
public:
    DcBlocker() = default;

    void set_pole(T pole) { pole_ = pole; }

    void reset() { last_in_ = T(0); last_out_ = T(0); }

    T process(T x) {
        // Snap the recursive output state: with a pole near 1 the tail decays
        // slowly toward zero and stalls in denormals with no FTZ guard. This is
        // exactly the pattern denormal.hpp documents. No-op above 1e-15.
        const T y = snap_to_zero(x - last_in_ + pole_ * last_out_);
        last_in_ = x;
        last_out_ = y;
        return y;
    }

    void process(T* samples, int n) {
        for (int i = 0; i < n; ++i)
            samples[i] = process(samples[i]);
    }
 
private:
    T pole_ = T(0.995);
    T last_in_ = T(0);
    T last_out_ = T(0);
};
 
} // namespace pulp::signal