effect_reverb.h

/*  Reverb for Teensy
 *
 *  Author: Joao Rossi Filho
 *          joaorossifilho@gmail.com
 *
 *  Soon I'll make a commit with nice comments and discription
 *
 * Copyright (c) 2016 Joao Rossi FIlho
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef effect_reverb_
#define effect_reverb_

#include <AudioStream.h> // github.com/PaulStoffregen/cores/blob/master/teensy4/AudioStream.h

#define APF1_BUF_LEN 600
#define APF2_BUF_LEN 1300
#define APF3_BUF_LEN 500

#define LPF1_BUF_LEN 1400
#define LPF2_BUF_LEN 1700
#define LPF3_BUF_LEN 1800
#define LPF4_BUF_LEN 2000

#define APF1_DLY_LEN 586
#define APF2_DLY_LEN 1239
#define APF3_DLY_LEN 485

#define LPF1_DLY_LEN 1398
#define LPF2_DLY_LEN 1637
#define LPF3_DLY_LEN 1774
#define LPF4_DLY_LEN 1947

#define LPF1_DLY_SEC 0.03171 
#define LPF2_DLY_SEC 0.03711
#define LPF3_DLY_SEC 0.04023
#define LPF4_DLY_SEC 0.04414


class AudioEffectReverb : public AudioStream
{
  public:
    AudioEffectReverb(void) : AudioStream(1, inputQueueArray) {
      init_comb_filters();
      clear_buffers();
      reverbTime(5.0);
    }
    virtual void update(void);
    void reverbTime(float);

  private:
    struct comb_apf {
      int32_t   g;
      int32_t   *buffer;
      uint32_t  buf_len;
      uint32_t  delay, rd_idx, wr_idx;
    };

    struct comb_lpf {
      int32_t   g1, g2, z1;
      int32_t   *buffer;
      uint32_t  buf_len;
      uint32_t  delay, rd_idx, wr_idx;
    };
    void init_comb_filters(void);
    void clear_buffers(void);
    static void _do_comb_apf(struct comb_apf *apf, int32_t *in_buf, int32_t *out_buf);
    static void _do_comb_lpf(struct comb_lpf *lpf, int32_t *in_buf, int32_t *out_buf);

    audio_block_t *inputQueueArray[1];

    struct comb_apf apf[3];
    struct comb_lpf lpf[4];

    float   reverb_time_sec;

    float   g_flt_apf[3];
    int32_t g_q31_apf[3];

    float   g1_flt_lpf[4];
    int32_t g1_q31_lpf[4];

    float   g2_flt_lpf;
    int32_t g2_q31_lpf;

    int32_t apf1_buf[APF1_BUF_LEN];
    int32_t apf2_buf[APF2_BUF_LEN];
    int32_t apf3_buf[APF3_BUF_LEN];

    int32_t lpf1_buf[LPF1_BUF_LEN];
    int32_t lpf2_buf[LPF2_BUF_LEN];
    int32_t lpf3_buf[LPF3_BUF_LEN];
    int32_t lpf4_buf[LPF4_BUF_LEN];

    int32_t q31_buf[AUDIO_BLOCK_SAMPLES];
    int32_t sum_buf[AUDIO_BLOCK_SAMPLES];
    int32_t aux_buf[AUDIO_BLOCK_SAMPLES];
};

#endif