/**

Integer 4-digit-seven-segment display driver (no libraries)

**/

























const int A      = 2;
const int B      = 3;
const int C      = 4;
const int D      = 5;
const int E      = 6;
const int F      = 7;
const int G      = 8;
const int DP     = 9;
const int seg[8] = {A, B, C, D, E, F, G, DP};
const int dig[4] = {10, 11, 12, 13};


// Single digit driver
void d7s(int digit, int num) {

  // Number combination - - - - - -
  const int n0[] = { A,B,C,D,E,F   };
  const int n1[] = {   B,C         };
  const int n2[] = { A,B,  D,E,  G };
  const int n3[] = { A,B,C,D,    G };
  const int n4[] = {   B,C,  F,  G };
  const int n5[] = { A,  C,D,F,  G };
  const int n6[] = { A,  C,D,E,F,G };
  const int n7[] = { A,B,C         };
  const int n8[] = { A,B,C,D,E,F,G };
  const int n9[] = { A,B,C,    F,G };
  // - - - - - - - - - - - - - - - 

  for (int pin : seg) { digitalWrite(pin, HIGH); }
  
  switch (num) {
    case 0:
      for (int pin : n0) { digitalWrite(pin, LOW); }
      break;
    case 1:
      for (int pin : n1) { digitalWrite(pin, LOW); }
      break;
    case 2:
      for (int pin : n2) { digitalWrite(pin, LOW); }
      break;
    case 3:
      for (int pin : n3) { digitalWrite(pin, LOW); }
      break;
    case 4:
      for (int pin : n4) { digitalWrite(pin, LOW); }
      break;
    case 5:
      for (int pin : n5) { digitalWrite(pin, LOW); }
      break;
    case 6:
      for (int pin : n6) { digitalWrite(pin, LOW); }
      break;
    case 7:
      for (int pin : n7) { digitalWrite(pin, LOW); }
      break;
    case 8:
      for (int pin : n8) { digitalWrite(pin, LOW); }
      break;
    case 9:
      for (int pin : n9) { digitalWrite(pin, LOW); }
      break;
  }

  digitalWrite(dig[digit], HIGH);
  digitalWrite(dig[digit], LOW);
}

// Decompose a number (0-9999) to get each digit
void dcnum(int number, int *n1000, int *n100, int *n10, int *n1) {
    *n1000 = number / 1000;
    number %= 1000;
    *n100 = number / 100;
    number %= 100;
    *n10 = number / 10;
    *n1 = number % 10;
}

// 4 digit driver
void d7s4d(int num) {
  int n1000, n100, n10, n1;
  dcnum(num, &n1000, &n100, &n10, &n1);

  d7s(0, n1000);
  d7s(1,  n100);
  d7s(2,   n10);
  d7s(3,    n1);
}

int counter = 9980;

// Delay variables
int cdly = 0;
int dly = 500;
void dlyf() {
  counter++;
  if (counter > 9999) counter = 0;
}

int main() {

  for (int pin : seg) { pinMode(pin, OUTPUT); }
  for (int pin : dig) { pinMode(pin, OUTPUT); }

  while (true) {
    // Displaying
    d7s4d(counter);

    // This replaces delay function because d7s has to execute everytime.
    // Note here that this is a sh1t code because i didnt come up with a better idea.
    cdly++;
    if (cdly > dly) {
      cdly = 0;
      dlyf();
    }
  }

}