gendyn.cpp

struct Gendyn2026
{
    struct Node
    {
        float x0 = 0.0f;
        float y0 = 0.0f;
    };
    alignas(16) std::array<Node, 256> nodes;
    alignas(16) double phase = 0.0;
    alignas(16) double phaseincrement = 0.0;
    size_t numnodes = 5;
    double sr = 0.0;
    float ampspread = 0.0f;
    float timespread = 0.0f;
    enum RANDOMDIST
    {
        RD_HYPCOS,
        RD_CAUCHY
    };
    RANDOMDIST timedist = RD_HYPCOS;
    RANDOMDIST ampdist = RD_HYPCOS;
    xenakios::Xoroshiro128Plus rng;
    Gendyn2026()
    {
        for (size_t i = 0; i < nodes.size(); ++i)
        {
            nodes[i] = {32.0f, 0.5f};
        }
    }
    void prepare(double samplerate)
    {
        sr = samplerate;
        phaseincrement = 1.0 / nodes[0].x0;
    }
    float step()
    {
        float y0 = nodes[0].y0;
        float y1 = nodes[1].y0;
        float y2 = nodes[2].y0;
        float y3 = nodes[3].y0;
        float intery = sst::basic_blocks::dsp::cubic_ipol(y0, y1, y2, y3, phase);
        // cubic interpolation will overshoot...
        intery = std::clamp(intery, -1.0f, 1.0f);
        phase += phaseincrement;
        if (phase >= 1.0)
        {
            // shift/rotate node array left, the current first node will become last node
            std::rotate(nodes.begin(), nodes.begin() + 1, nodes.begin() + numnodes);
            float x = nodes[numnodes - 1].x0;
            if (timedist == RD_HYPCOS)
                x += rng.nextHypCos(0.0, timespread);
            else if (timedist == RD_CAUCHY)
                x += rng.nextCauchy(0.0, timespread);
            x = reflect_value(1.0f, x, 16.0f);
            nodes[numnodes - 1].x0 = x;
            float y = nodes[numnodes - 1].y0;
            if (ampdist == RD_HYPCOS)
                y += rng.nextHypCos(0.0, ampspread);
            else if (ampdist == RD_CAUCHY)
                y += rng.nextCauchy(0.0, ampspread);
            y = reflect_value(-0.5f, y, 0.5f);
            nodes[numnodes - 1].y0 = y;
            phaseincrement = 1.0 / nodes[0].x0;
            phase = 0.0;
        }
        return intery;
    }
    
};