Audio/effect_tape_delay.cpp at master · BleepLabs/Audio · GitHub

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/* Audio Library for Teensy 3.X
 * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
 *
 * Development of this audio library was funded by PJRC.COM, LLC by sales of
 * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
 * open source software by purchasing Teensy or other PJRC products.
 *
 * 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, development funding 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.

 Interpolated delay time gives delay effect with a tape like response.
 Control of this interpolation speed and delay sample rate is now possible

 todo:
 arbitrary sample rate control rather than just divide
 interpolate between sample mode rather than interpolate time
 arbitraty multi tap

 */

#include "effect_tape_delay.h"
#include "arm_math.h"

void AudioEffectTapeDelay::begin(short *delayline, uint32_t max_len, uint32_t dly_len, short redux, short lerp)
{
  max_dly_len = max_len - 1;

  desired_delay_length = dly_len;
  if (desired_delay_length > max_dly_len) {
    desired_delay_length = max_dly_len;
  }
  l_delayline = delayline;
  write_head = 0;

  rate_redux = redux;
  lerp_len = lerp;
}


void AudioEffectTapeDelay::sampleRate(short redux)
{


  rate_redux = redux;
}


uint32_t AudioEffectTapeDelay::length(uint32_t dly_len)
{
  desired_delay_length = dly_len;
  if (desired_delay_length > max_dly_len) {
    desired_delay_length = max_dly_len;
  }
  return delay_length;

}

uint32_t AudioEffectTapeDelay::length_no_lerp(uint32_t dly_len)
{
  delay_length = dly_len;
  desired_delay_length=dly_len;
  if (delay_length > max_dly_len) {
    delay_length = max_dly_len;
  }
  return delay_length;

}

void AudioEffectTapeDelay::update(void)
{
  audio_block_t *block;
  short *bp;
  //static uint32_t preva;
  static short tick, tock;
  int input1;
static byte mm;
  if (l_delayline == NULL)return;
  uint32_t max_dly_len_m = max_dly_len;
  block = receiveWritable(0);
  if (block) {
    bp = block->data;

    for (int i = 0; i < AUDIO_BLOCK_SAMPLES; i++) {

      tick++;
      if (tick > lerp_len) {

        if (delay_length < desired_delay_length - 1) {
          delay_length++;
        }

        if (delay_length > desired_delay_length + 1) {
          delay_length--;
        }
        tick = 0;
      }


      tock++;
      if (tock > rate_redux) {
        tock = 0;
        write_head++;
      }
      if (write_head >= max_dly_len_m) {
        write_head = 0;
      }

      read_head = ((write_head) + delay_length);

      if (read_head > (max_dly_len_m - 1)) {
        read_head -= (max_dly_len_m);
      }

      l_delayline[write_head] = *bp ;
      *bp++ = l_delayline[read_head];
    }

    transmit(block);
    release(block);
  }
}