/*
   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
  
*/

#include <Arduino.h>
#include "effect_delay_ext8.h"

#define SPISETTING SPISettings(20000000, MSBFIRST, SPI_MODE0)

#define SPIRAM_MOSI_PIN 11   //-----------------
#define SPIRAM_MISO_PIN 12   // for Teensy 4.1
#define SPIRAM_SCK_PIN 13    //
#define SPIRAM_CS_PIN 36     //-----------------

#define MEMBOARD_CS0_PIN 2
#define MEMBOARD_CS1_PIN 3
#define MEMBOARD_CS2_PIN 4

void AudioEffectDelayExternal8::update(void)
{
	audio_block_t *block;
	uint32_t n, channel, read_offset;

	// grab incoming data and put it into the memory
	block = receiveReadOnly();
	if (block) {
		if (head_offset + AUDIO_BLOCK_SAMPLES <= memory_length) {
			// a single write is enough
			write(head_offset, AUDIO_BLOCK_SAMPLES, block->data);
			head_offset += AUDIO_BLOCK_SAMPLES;
		} else {
			// write wraps across end-of-memory
			n = memory_length - head_offset;
			write(head_offset, n, block->data);
			head_offset = AUDIO_BLOCK_SAMPLES - n;
			write(0, head_offset, block->data + n);
		}
		release(block);
	} else {
		// if no input, store zeros, so later playback will
		// not be random garbage previously stored in memory
		if (head_offset + AUDIO_BLOCK_SAMPLES <= memory_length) {
			zero(head_offset, AUDIO_BLOCK_SAMPLES);
			head_offset += AUDIO_BLOCK_SAMPLES;
		} else {
			n = memory_length - head_offset;
			zero(head_offset, n);
			head_offset = AUDIO_BLOCK_SAMPLES - n;
			zero(0, head_offset);
		}
	}

	// transmit the delayed outputs
	for (channel = 0; channel < 8; channel++) {
		if (!(activemask & (1<<channel))) continue;
		block = allocate();
		if (!block) continue;
		// compute the delayed location where we read
		if (delay_length[channel] <= head_offset) {
			read_offset = head_offset - delay_length[channel];
		} else {
			read_offset = memory_length + head_offset - delay_length[channel];
		}
		if (read_offset + AUDIO_BLOCK_SAMPLES <= memory_length) {
			// a single read will do it
			read(read_offset, AUDIO_BLOCK_SAMPLES, block->data);
		} else {
			// read wraps across end-of-memory
			n = memory_length - read_offset;
			read(read_offset, n, block->data);
			read(0, AUDIO_BLOCK_SAMPLES - n, block->data + n);
		}
		transmit(block, channel);
		release(block);
	}
}

uint32_t AudioEffectDelayExternal8::allocated = 0;

void AudioEffectDelayExternal8::initialize(uint32_t samples)
{
	uint32_t memsize, avail;

	activemask = 0;
	head_offset = 0;

	SPI.setMOSI(SPIRAM_MOSI_PIN);
	SPI.setMISO(SPIRAM_MISO_PIN);
	SPI.setSCK(SPIRAM_SCK_PIN);

	SPI.setCS(SPIRAM_CS_PIN); // added for Teensy 4.1
	SPI.begin();	
	
	memsize = (2^23); // 8388608 bytes
	pinMode(SPIRAM_CS_PIN, OUTPUT);
	digitalWriteFast(SPIRAM_CS_PIN, HIGH);

	avail = memsize - allocated;
	if (avail < AUDIO_BLOCK_SAMPLES*2+1) {
		return;
	}
	if (samples > avail) samples = avail;
	memory_begin = allocated;
	allocated += samples;
	memory_length = samples;

	zero(0, memory_length);
}

void AudioEffectDelayExternal8::read(uint32_t offset, uint32_t count, int16_t *data)
{
	uint32_t addr = memory_begin + offset;

	addr *= 2;
	SPI.beginTransaction(SPISETTING);
	digitalWriteFast(SPIRAM_CS_PIN, LOW);
	SPI.transfer16((0x03 << 8) | (addr >> 16));
	SPI.transfer16(addr & 0xFFFF);
	while (count) {
		*data++ = (int16_t)(SPI.transfer16(0));
		count--;
	}
	digitalWriteFast(SPIRAM_CS_PIN, HIGH);
	SPI.endTransaction();
}

void AudioEffectDelayExternal8::write(uint32_t offset, uint32_t count, const int16_t *data)
{
	uint32_t addr = memory_begin + offset;

	addr *= 2;

	SPI.beginTransaction(SPISETTING);
	digitalWriteFast(SPIRAM_CS_PIN, LOW);
	SPI.transfer(0x06); //write-enable before every write
	digitalWriteFast(SPIRAM_CS_PIN, HIGH);
	asm volatile ("NOP\n NOP\n NOP\n NOP\n NOP\n NOP\n");
	digitalWriteFast(SPIRAM_CS_PIN, LOW);
	SPI.transfer16((0x02 << 8) | (addr >> 16));
	SPI.transfer16(addr & 0xFFFF);
	while (count) {
		int16_t w = 0;
		if (data) w = *data++;
		SPI.transfer16(w);
		count--;
	}
	digitalWriteFast(SPIRAM_CS_PIN, HIGH);
	SPI.endTransaction();	
}