soothe2-re/dsp/filter.hpp

#pragma once
#include <cstddef>
#include <cstdint>
#include <cstring>

constexpr size_t MAX_BANDS = 8;

struct FilterParams {
    float freq;
    float q;
    float gain;
    int type;
    int on;
};

struct FilterState {
    float x1, x2, y1, y2;
};

class DigitalFilter {
public:
    DigitalFilter();
    void setParams(const FilterParams& p, float sample_rate);
    float process(float x);
    
private:
    FilterParams params_;
    FilterState state_;
    float b0, b1, b2, a1, a2;
    float fs_;
    
    void updateCoeffs();
};

class FilterGraph {
public:
    FilterGraph();
    void processBlock(float* in, float* out, size_t n, const FilterParams* bands, size_t num_bands);
    
private:
    DigitalFilter filters_[MAX_BANDS];
};