#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "nvs.h"
#include "nvs_flash.h"
#include "esp_system.h"
#include "esp_log.h"
#include "driver/i2s.h"

//Board ESP32 Dev Module

//error type
esp_err_t err;

//buffers
int rxbuf[256], txbuf[256];

#define SAMPLE_RATE 8000
#define BUFF_COU 8
#define BUFF_LEN 64
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
void setup() {
  Serial.begin(115200);
  delay (1000);
  //enable MCLK on GPIO0
  //REG_WRITE(PIN_CTRL, 0xFF0); 
  //PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_CLK_OUT1);
//------------------------------------------------------------
  i2s_config_t i2s_config = {
        .mode                 = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_TX  | I2S_MODE_RX), // i2s_mode_t  work mode
        .sample_rate          = SAMPLE_RATE,                        // int sample rate
        .bits_per_sample      = I2S_BITS_PER_SAMPLE_16BIT,    // i2s_bits_per_sample_t bits per sample
        .channel_format       = I2S_CHANNEL_FMT_ONLY_LEFT,   // i2s_channel_fmt_t channel format
        .communication_format = I2S_COMM_FORMAT_I2S_MSB,     // i2s_comm_format_t communication format
        .intr_alloc_flags     = 0,      // int Flags used to allocate the interrupt. One or multiple (ORred) ESP_INTR_FLAG_* values. See esp_intr_alloc.h for more info
        .dma_buf_count        = BUFF_COU * 2,      // int DMA Buffer Count
        .dma_buf_len          = BUFF_LEN,    // int DMA Buffer Length
        .use_apll             = true,   // bool using APLL as main clock, enable it to get accurate clock
        .tx_desc_auto_clear   = true,   // bool auto clear tx descriptor if there is underflow condition (helps in avoiding noise in case of data unavailability)
        .fixed_mclk           = true   // int using fixed MCLK output. If use_apll = true and fixed_mclk > 0, then the clock output for is fixed and equal to the fixed_mclk value
    };

    err = i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);

    if (err != ESP_OK) {
       Serial.print("Failed installing driver: ");
       Serial.print(err);
       while (true);
     }

//------------------------------------------------------------
    i2s_pin_config_t pin_config = {
        .bck_io_num   = 32,   //  INMP441 SD 32,MAX98357A BCLK 32
        .ws_io_num    = 25,   //  INMP441 WS 25,MAX98357A LRC 25
        .data_out_num = 15,   //  MAX98537A DIN 15 OUT
        .data_in_num  = 33    //  INMP441 SCK 33 IN
    };

   err = i2s_set_pin(I2S_NUM_0, &pin_config);

   if (err != ESP_OK) {
      Serial.print("Failed setting pin: ");
      Serial.print(err);
      while (true);
   }

   Serial.println("I2S driver installed.");
 }
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

void loop() {
    size_t readsize = 0; 
    //read 256 samples (128 stereo samples)
    err = i2s_read(I2S_NUM_0,&rxbuf[0],256*2, &readsize, 1000);

    if (err == ESP_OK && readsize==256*2) {
          for (int i=0; i<256; i++) {
		        txbuf[i] = rxbuf[i];
          }
          //write 
          i2s_write(I2S_NUM_0, &txbuf[0],256*2, &readsize, 1000);
      }   // end of cycle
}         // end of void loop()