#define DATA_PIN  2  // Pin connected to DS of 74HC595
#define LATCH_PIN 4  // Pin connected to STCP of 74HC595
#define CLOCK_PIN 3 // Pin connected to SHCP of 74HC595

// How many of the shift registers
#define NUM_SHIFT_REGS 4

const uint8_t numOfRegisterPins = NUM_SHIFT_REGS * 8;

bool registers[numOfRegisterPins];

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

void loop() {
  // Call the chaser effect functions
  chaserEffect1();
  delay(100);
  chaserEffect2();
  delay(100);
  clearRegisters();
  chaserEffect3();
  delay(100);
  chaserEffect4();
  delay(100);
  chaserEffect5();
  delay(100);
  chaserEffect6();
  delay(100);
  clearRegisters();
  chaserEffect7();
  delay(100);
  chaserEffect8();
  delay(100);
  clearRegisters();
  chaserEffect9();
  delay(100);
  chaserEffect10();
  delay(100);
  clearRegisters();
  chaserEffect11();
  delay(100);
  chaserEffect12();
  delay(100);
  chaserEffect13();
  delay(100);
  chaserEffect14();
  delay(100);
  chaserEffect15();
  delay(100);
}

void chaserEffect1() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    clearRegisters();
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect2() {
  for (int i = numOfRegisterPins - 1; i >= 0; i--) {
    clearRegisters();
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect3() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect4() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, LOW);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect5() {
  for (int i = numOfRegisterPins - 1; i >= 0; i--) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect6() {
  for (int i = numOfRegisterPins - 1; i >= 0; i--) {
    setRegisterPin(i, LOW);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect7() {
  for (int i = 0; i < numOfRegisterPins; i += 2) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect8() {
  for (int i = numOfRegisterPins - 1; i >= 0; i -= 2) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect9() {
  for (int i = 0; i < numOfRegisterPins; i += 4) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect10() {
  for (int i = numOfRegisterPins - 1; i >= 0; i -= 4) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect11() {
  for (int i = numOfRegisterPins - 1; i >= 0; i -= 7) {
    setRegisterPin(i, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect12() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, HIGH);
    setRegisterPin(i + 1, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect13() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, HIGH);
    setRegisterPin(i + 1, LOW);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect14() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, LOW);
    setRegisterPin(i + 1, HIGH);
    writeRegisters();
    delay(100);
  }
}

void chaserEffect15() {
  for (int i = 0; i < numOfRegisterPins; i++) {
    setRegisterPin(i, HIGH);
    setRegisterPin(i + 3, HIGH);
    writeRegisters();
    delay(100);
  }
}

void clearRegisters() {
  // Reset all register pins
  for (int i = numOfRegisterPins - 1; i >= 0; i--) {
    registers[i] = LOW;
  }
}

void setRegisterPin(int index, int value) {
  // Set an individual pin HIGH or LOW
  registers[index] = value;
}

void writeRegisters() {
  // Set and display registers
  digitalWrite(LATCH_PIN, LOW);

  for (int i = numOfRegisterPins - 1; i >= 0; i--) {
    digitalWrite(CLOCK_PIN, LOW);
    digitalWrite(DATA_PIN, registers[i]);
    digitalWrite(CLOCK_PIN, HIGH);
  }

  digitalWrite(LATCH_PIN, HIGH);
}