#include <Arduino.h>

char arr[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
const uint16_t sizeOfArr = sizeof(arr);

void setup() {
  Serial.begin(9600);
  generate_CRC32();
}

void loop() {
  /* Empty loop */
}

uint32_t generate_CRC32(void) {

  const uint32_t crc_table[16] = {

    0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,

    0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,

    0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,

    0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c

  };

  uint32_t crc = ~0L;

  for (uint32_t index = 0 ; index < sizeOfArr - 1  ; ++index) {

    crc = crc_table[(crc ^ arr[index]) & 0x0f] ^ (crc >> 4);

    crc = crc_table[(crc ^ (arr[index] >> 4)) & 0x0f] ^ (crc >> 4);

    crc = ~crc;

  }
  Serial.println("");
  Serial.print("CRC32 = ");
  Serial.println(crc,HEX);
  return crc;
}