delay.c

#include "delay.h"

radspa_t * delay_create(uint32_t init_var);
radspa_descriptor_t delay_desc = {
    .name = "delay_static",
    .id = 42069,
    .description = "simple delay with ms input and feedback\n"
                    "init_var: delay buffer length in ms, default 500",
    .create_plugin_instance = delay_create,
    .destroy_plugin_instance = radspa_standard_plugin_destroy
};

#define DELAY_NUM_SIGNALS 7
#define DELAY_OUTPUT 0
#define DELAY_INPUT 1
#define DELAY_TIME 2
#define DELAY_FEEDBACK 3
#define DELAY_LEVEL 4
#define DELAY_DRY_VOL 5
#define DELAY_REC_VOL 6

void delay_run(radspa_t * delay, uint16_t num_samples, uint32_t render_pass_id){
    radspa_signal_t * output_sig = radspa_signal_get_by_index(delay, DELAY_OUTPUT);
    delay_data_t * data = delay->plugin_data;
    int16_t * buf = delay->plugin_table;
    radspa_signal_t * input_sig = radspa_signal_get_by_index(delay, DELAY_INPUT);
    radspa_signal_t * time_sig = radspa_signal_get_by_index(delay, DELAY_TIME);
    radspa_signal_t * feedback_sig = radspa_signal_get_by_index(delay, DELAY_FEEDBACK);
    radspa_signal_t * level_sig = radspa_signal_get_by_index(delay, DELAY_LEVEL);
    radspa_signal_t * dry_vol_sig = radspa_signal_get_by_index(delay, DELAY_DRY_VOL);
    radspa_signal_t * rec_vol_sig = radspa_signal_get_by_index(delay, DELAY_REC_VOL);

    static int16_t ret = 0;
    
    int32_t buffer_size = delay->plugin_table_len;
    int32_t time = radspa_signal_get_value(time_sig, 0, render_pass_id);
    if(time < 0) time = -time;
    if(time > data->max_delay) time = data->max_delay;
    if(time != data->time_prev){
        data->read_head_position = data->write_head_position;
        data->read_head_position -= time * (48000/1000);
        if(data->read_head_position < 0) data->read_head_position += buffer_size;
        data->time_prev = time;
    }
    int16_t fb = radspa_signal_get_value(feedback_sig, 0, render_pass_id);
    int16_t level = radspa_signal_get_value(level_sig, 0, render_pass_id);

    int16_t dry_vol = radspa_signal_get_value(dry_vol_sig, 0, render_pass_id);
    int16_t rec_vol = radspa_signal_get_value(rec_vol_sig, 0, render_pass_id);

    
    for(uint16_t i = 0; i < num_samples; i++){

        data->write_head_position++;
        while(data->write_head_position >= buffer_size) data->write_head_position -= buffer_size; // maybe faster than %
        data->read_head_position++;
        while(data->read_head_position >= buffer_size) data->read_head_position -= buffer_size;
    
        int16_t dry = radspa_signal_get_value(input_sig, i, render_pass_id);
        int16_t wet = buf[data->read_head_position];

        if(rec_vol){
            buf[data->write_head_position] = radspa_add_sat(radspa_mult_shift(rec_vol, dry), radspa_mult_shift(wet,fb));
        }
        
        ret = radspa_add_sat(radspa_mult_shift(dry_vol,dry), radspa_mult_shift(wet,level));

        radspa_signal_set_value(output_sig, i, ret);
    }
}