//https://github.com/rmorenojr/ElegooTutorial/blob/master/Lesson%2024%20-%2074HC595%20Shift%20Register/SR_74HC595_32bit/SR_74HC595_32bit.ino
const int tDelay   = 100;
const int dataPin  = 8;
const int latchPin = 9;
const int clockPin = 10;

bool DirectionState = 0;

void updateShiftRegister(unsigned long leds, bool isMSBFIRST = true){
    unsigned int leds16 = int(leds);
    unsigned int leds32 = int(leds>>16);
    byte low16LED  = lowByte(leds16);
    byte high16LED = highByte(leds16);
    byte low32LED  = lowByte(leds32);
    byte high32LED = highByte(leds32);

    digitalWrite(latchPin, LOW);
    if (isMSBFIRST == false) {
        shiftOut(dataPin, clockPin, LSBFIRST, low16LED);
        shiftOut(dataPin, clockPin, LSBFIRST, high16LED);  
        shiftOut(dataPin, clockPin, LSBFIRST, low32LED);
        shiftOut(dataPin, clockPin, LSBFIRST, high32LED);  
    } 
    else {
        shiftOut(dataPin, clockPin, MSBFIRST, high32LED);
        shiftOut(dataPin, clockPin, MSBFIRST, low32LED);
        shiftOut(dataPin, clockPin, MSBFIRST, high16LED);
        shiftOut(dataPin, clockPin, MSBFIRST, low16LED);
    }
    digitalWrite(latchPin, HIGH);
}

void setup(){
    pinMode(latchPin, OUTPUT);
    pinMode(dataPin,  OUTPUT);  
    pinMode(clockPin, OUTPUT);
}

void loop(){
    unsigned long leds = 0B11111111111111111111111111111111;
/*    updateShiftRegister(leds);
    delay(tDelay);
    leds = 0B00000000000000000000000000000000;
    updateShiftRegister(leds);
    delay(tDelay);
    leds = 0B11111111111111111111111111111111;
    updateShiftRegister(leds);
    delay(tDelay);*/

    for (int i = 8; i < 32; i++){
        leds = 0B00000000000000000000000000000000;
        bitSet(leds, i);
        updateShiftRegister(leds, DirectionState);
        delay(tDelay);
    }
    for (int i = 32; i > 8; i--){
        leds = 0B00000000000000000000000000000000;
        bitSet(leds, i);
        updateShiftRegister(leds, DirectionState);
        delay(tDelay);
    }
//    DirectionState = !DirectionState;
}