#include <stdio.h>          //provides printf function
#include "pico/stdlib.h"    //provides standard library for the pico
#include "hardware/adc.h"   //configure adc
#include "hardware/dma.h"   //enable DMA transfers

// Channel 0 is GPIO26
#define CAPTURE_CHANNEL 2
#define CAPTURE_DEPTH 1000

uint16_t capture_buf[CAPTURE_DEPTH];

void printbuffer()
{
  // Print samples to stdout so you can display them in pyplot, excel, matlab
  for (int i = 0; i < CAPTURE_DEPTH; ++i) {
      printf("%-3d, ", capture_buf[i]);
      if (i % 10 == 9)
          printf("\n");
  }
}

int main()
{
    stdio_init_all();
    adc_init();
    adc_gpio_init(26 + CAPTURE_CHANNEL);
    adc_select_input(CAPTURE_CHANNEL);

    adc_fifo_setup(
        true,    // Write each completed conversion to the sample FIFO
        true,    // Enable DMA data request (DREQ)
        1,       // DREQ (and IRQ) asserted when at least 1 sample present
        false,   // We won't see the ERR bit because of 8 bit reads; disable.
        false    // Do not shift each sample to 8 bits when pushing to FIFO
    );

    // Divisor of 0 -> full speed. Free-running capture with the divider is
    // equivalent to pressing the ADC_CS_START_ONCE button once per `div + 1`
    // cycles (div not necessarily an integer). Each conversion takes 96
    // cycles, so in general you want a divider of 0 (hold down the button
    // continuously) or > 95 (take samples less frequently than 96 cycle
    // intervals). This is all timed by the 48 MHz ADC clock.
    adc_set_clkdiv(0);

    printf("Arming DMA\n");
    sleep_ms(1000);
    
    // Set up the DMA to start transferring data as soon as it appears in FIFO
    uint dma_chan = dma_claim_unused_channel(true);
    dma_channel_config cfg = dma_channel_get_default_config(dma_chan);

    // Reading from constant address, writing to incrementing byte addresses
    channel_config_set_transfer_data_size(&cfg, DMA_SIZE_16);
    channel_config_set_read_increment(&cfg, false);
    channel_config_set_write_increment(&cfg, true);

    // Pace transfers based on availability of ADC samples
    channel_config_set_dreq(&cfg, DREQ_ADC);

    dma_channel_configure(dma_chan, &cfg,
        capture_buf,    // dst
        &adc_hw->fifo,  // src
        CAPTURE_DEPTH,  // transfer count
        true            // start immediately
    );

    printf("Starting capture\n");
    adc_run(true);

    // Once DMA finishes, stop any new conversions from starting, and clean up
    // the FIFO in case the ADC was still mid-conversion.
    dma_channel_wait_for_finish_blocking(dma_chan);
    printf("Capture finished\n");
    adc_run(false);
    adc_fifo_drain();
    printbuffer();

    while (true){
    }
}