MicroDexed/effect_delay_ext8.h

/*
   MicroDexed

   MicroDexed is a port of the Dexed sound engine
   Dexed ist heavily based on https://github.com/google/music-synthesizer-for-android

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA

  effect_delay_ext8 is a special delay class for APS6404L-3SQR based memory chips on 
  a Teensy-4.1. The cod is a combination of the PJRC delay_ext class and suggestions
  from https://forum.pjrc.com/threads/29276-Limits-of-delay-effect-in-audio-library/page5?highlight=APS6404L-3SQR
  
*/

#pragma once

#include "Arduino.h"
#include "AudioStream.h"
#include "spi_interrupt.h"

class AudioEffectDelayExternal8 : public AudioStream
{
public:
	AudioEffectDelayExternal8() : AudioStream(1, inputQueueArray) {
		initialize(4194304);
	}
	AudioEffectDelayExternal8(float milliseconds=1e6)
	  : AudioStream(1, inputQueueArray) {
		uint32_t n = (milliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0f))+0.5f;
		initialize(n);
	}

	void delay(uint8_t channel, float milliseconds) {
		if (channel >= 8) return;
		if (milliseconds < 0.0f) milliseconds = 0.0f;
		uint32_t n = (milliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0f))+0.5f;
		n += AUDIO_BLOCK_SAMPLES;
		if (n > memory_length - AUDIO_BLOCK_SAMPLES)
			n = memory_length - AUDIO_BLOCK_SAMPLES;
		delay_length[channel] = n;
		uint8_t mask = activemask;
		if (activemask == 0) AudioStartUsingSPI();
		activemask = mask | (1<<channel);
	}
	void disable(uint8_t channel) {
		if (channel >= 8) return;
		uint8_t mask = activemask & ~(1<<channel);
		activemask = mask;
		if (mask == 0) AudioStopUsingSPI();
	}
	virtual void update(void);
private:
	void initialize(uint32_t samples);
	void read(uint32_t address, uint32_t count, int16_t *data);
	void write(uint32_t address, uint32_t count, const int16_t *data);
	void zero(uint32_t address, uint32_t count) {
		write(address, count, NULL);
	}
	uint32_t memory_begin;    // the first address in the memory we're using
	uint32_t memory_length;   // the amount of memory we're using
	uint32_t head_offset;     // head index (incoming) data into external memory
	uint32_t delay_length[8]; // # of sample delay for each channel (128 = no delay)
	uint8_t  activemask;      // which output channels are active
	static uint32_t allocated;
	audio_block_t *inputQueueArray[1];
};