#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include "delay.h"

void delay_init(
    struct delay * delay
) {
    delay->duration = 15000;
    delay->mix = 0.8;
    delay->feedback = 0.6;

    delay->buf_idx = 0;
    delay->buf = calloc( delay->duration, sizeof(float) );
}

void delay_process(
    struct delay * delay,
    size_t frame_size,
    float const * in,
    float * out
) {
    for( size_t i = 0; i < frame_size; ++i ) {
        out[i] =
            (1.0 - delay->mix) * in[i]
            + delay->mix * delay->buf[ delay->buf_idx ];

        delay->buf[ delay->buf_idx ] *= delay->feedback;
        delay->buf[ delay->buf_idx ] += (1.0 - delay->feedback) * in[i];
        delay->buf_idx = (delay->buf_idx + 1) % delay->duration;
    }
}