[SOLVED] IRQ handling problem (updated: electronic interference?)

const uint8_t irq_pins[] = IRQ_PINS;
const ExtIntTriggerMode irq_mode[] = IRQ_MODE;
const uint16_t irq_ids[] = IRQ_IDS;
const WiringPinMode irq_pull[] = IRQ_PULL;
uint16_t irq_event = 0; // each bit one irq, max 16
uint16_t irq_state = 0; // each bit one irq, max 16
uint16_t irq_stateA = 0; // each bit one irq, max 16
uint16_t irq_stateB = 0; // each bit one irq, max 16
uint16_t irq_stateC = 0; // each bit one irq, max 16

// minimal activity in irqhandler
void irqhandler(void) {
if (bIRQIgnore || event) return;
irq_stateA = GPIOA->regs->IDR;
irq_stateB = GPIOB->regs->IDR;
irq_stateC = GPIOC->regs->IDR;
event = true;
}

// enable IRQ for specified pins
void setupIRQ() {
for (int i = 0; i < arrlen(irq_pins); i++) {
pinMode(irq_pins[i], irq_pull[i]);

// give time to settle, before that initial state was false.
delay(10);

// read current pin states
irq_stateA = GPIOA->regs->IDR;
irq_stateB = GPIOB->regs->IDR;
irq_stateC = GPIOC->regs->IDR;

// set "old" IRQ states
for (uint8_t i = 0; i < arrlen(irq_pins); i++) {
if (getIRQPinState(irq_pins[i])) {
sbi(irq_state, i);
} else {
cbi(irq_state, i);
}
}
attachInterrupt(irq_pins[i], irqhandler, irq_mode[i]);
}
bIRQIgnore = false;
}

void checkIRQ() {
if (event) {

// check all PINs to see which changed/triggered
for (uint8_t i = 0; i < arrlen(irq_pins); i++) {
uint8_t pnew = getIRQPinState(irq_pins[i]);
uint8_t pold = gbi(irq_state, i);

if (pnew != pold) {
// set new value
if (irq_mode[i] == CHANGE) {
if (pnew) sbi(irq_state, i);
else cbi(irq_state, i);
}
// set to high, does not check for falling edge
if (irq_mode[i] == RISING) {
cbi(irq_state, i);
}
// set to low, does not check for rising edge
if (irq_mode[i] == FALLING) {
sbi(irq_state, i);
}

Serial.println(pnew ? "CLOSED" : "OPENED");

}
}
event = false;
}
}

// helper to get single pin status
uint8_t getIRQPinState(uint8_t irq) {
if (irq < 16) {
return gbi(irq_stateA, irq);
}
if (irq < 32) {
return gbi(irq_stateB, irq - 16);
}

return gbi(irq_stateC, irq - 32);
}