svf.cc.in

#include <cmath>
#include <lv2.h>


#include "state-variable-filter/svf-v2.h"
#include "common.cc"

struct svf {
    float *ports[7];
    svf_v2::lowbandhighpass filter;
    float sample_rate;
    float freq;
    float q;
    float lowgain;
    float bandgain;
    float highgain;
    unsigned frame_index;
    svf(float sample_rate) : sample_rate(sample_rate), freq(0.01f), q(0.5f), lowgain(0.0f), bandgain(0.0f), highgain(0.0f), frame_index(0) {

    }
};

static LV2_Handle instantiate(const LV2_Descriptor *descriptor, double sample_rate, const char *bundle_path, const LV2_Feature *const *features)
{
    return (LV2_Handle)(new svf(sample_rate));
}

static void cleanup(LV2_Handle instance)
{
    delete ((svf*)instance);
}

static void connect_port(LV2_Handle instance, uint32_t port, void *data_location)
{
    ((svf*)instance)->ports[port] = (float*)data_location;
}

#define ALPHA 0.99f

#define PARAM_UPDATE 8

static void run(LV2_Handle instance, uint32_t sample_count)
{
    svf *tinstance = (svf*)(instance);

    const float p_freq = tinstance->ports[2][0] / tinstance->sample_rate;
    const float p_q = tinstance->ports[3][0];
    const float p_lowgain = db_to_gain(tinstance->ports[4][0]);
    const float p_bandgain = db_to_gain(tinstance->ports[5][0]);
    const float p_highgain = db_to_gain(tinstance->ports[6][0]);

    for(uint32_t sample_index = 0; sample_index < sample_count; ++sample_index)
    {
        if (0 == tinstance->frame_index % PARAM_UPDATE)
        {
            tinstance->freq = ALPHA * tinstance->freq + (1.0f - ALPHA) * p_freq;
            tinstance->q = ALPHA * tinstance->q + (1.0f - ALPHA) * p_q;
            tinstance->lowgain = ALPHA * tinstance->lowgain + (1.0f - ALPHA) * p_lowgain;
            tinstance->bandgain = ALPHA * tinstance->bandgain + (1.0f - ALPHA) * p_bandgain;
            tinstance->highgain = ALPHA * tinstance->highgain + (1.0f - ALPHA) * p_highgain;
        }
        ++(tinstance->frame_index);
 
        tinstance->filter.process
        (
          tinstance->ports[0] + sample_index, 
          tinstance->ports[1] + sample_index, 
          1, 
          tinstance->highgain, 
          tinstance->bandgain, 
          tinstance->lowgain, 
          tinstance->freq, 
          tinstance->q
        );
    }
}

static const LV2_Descriptor descriptor = {
    "http://fps.io/plugins/state-variable-filter-VERSION",
    instantiate,
    connect_port,
    nullptr, // activate
    run,
    nullptr, // deactivate
    cleanup,
    nullptr // extension_data
};

LV2_SYMBOL_EXPORT const LV2_Descriptor* lv2_descriptor (uint32_t index)
{
    if (0 == index) return &descriptor;
    else return nullptr;
}