#define DATA_PIN  8  
#define LATCH_PIN 9  
#define CLOCK_PIN 10 

#define MAX_ELEMENTS 3
#define COUNT_SEGMENTS 8

static const size_t g_primes[] = {
  2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 
127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 
257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 
401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 
563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 
709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 
877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997
};

void setup() {
  pinMode(DATA_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);
}

void loop() {
    static int counter;
    show_number(g_primes[counter++]);
    counter = counter % (sizeof(g_primes) / sizeof(g_primes[0]));
    delay(500);
}

static void send_array(const uint8_t *arr, size_t array_size) {
  for (int i = array_size - 1; i >= 0; i--) {
    digitalWrite(DATA_PIN, arr[i] == 0 ? LOW : HIGH);

    digitalWrite(CLOCK_PIN, HIGH);
    delay(1);
    digitalWrite(CLOCK_PIN, LOW);
    delay(1);
  }
}

static const uint8_t g_digits[][COUNT_SEGMENTS] = {
  {1, 1, 1, 1, 1, 1, 0, 0},
  {0, 1, 1, 0, 0, 0, 0, 0},
  {1, 1, 0, 1, 1, 0, 1, 0},
  {1, 1, 1, 1, 0, 0, 1, 0},
  {0, 1, 1, 0, 0, 1, 1, 0},
  {1, 0, 1, 1, 0, 1, 1, 0},
  {1, 0, 1, 1, 1, 1, 1, 0},
  {1, 1, 1, 0, 0, 0, 0, 0},
  {1, 1, 1, 1, 1, 1, 1, 0},
  {1, 1, 1, 1, 0, 1, 1, 0}
};

static const uint8_t g_clear[COUNT_SEGMENTS] = {
  0, 0, 0, 0, 0, 0, 0, 0
};

static const int g_power10[] = {1, 10, 100, 1000, 10000};

static void show_number(int number) {
  digitalWrite(LATCH_PIN, LOW);

  for (int position = 0; position < MAX_ELEMENTS; position++) {
    int div = number / g_power10[position];

    // remove leading zeros
    if (div)
      send_array(g_digits[div % 10], COUNT_SEGMENTS);
    else
      send_array(g_clear, COUNT_SEGMENTS);
  }

  digitalWrite(LATCH_PIN, HIGH);
}