Delay, multi milliseconds, on the STM32F0, again..

Let's assume you're only looking a 3 inputs and controlling 2 outputs. 

Create a data structure to represent the look-up table

typedef union
{
	struct
	{
		uint8_t data[2]; // byte 0 is current state, byte 1 is last state
	}Byte;
	struct
	{
		uint8_t pa1:1;
		uint8_t pa2:1;
		uint8_t pc13:1;
		uint8_t :5;
	}Status;
}InputStatus_t;

Using EXTI for the input pins, we can use the HAL GPIO callbacks to set the input pin states. I've tested on a Nucleo-G071RB which uses a Rising and Falling callback where some STM's use 1 callback, but concept is the same.  

/*
 * Description: Update pin status for specific input.
 * Input: pin data structure, pin to update, the pin state
 */
void GPIO_UpdatePinStatus(InputStatus_t *input, uint8_t pin, GPIO_PinState pinStatus)
{
	switch(pin)
	{
	case 0:
		input->Status.pa1 = pinStatus;
		break;
	case 1:
		input->Status.pa2 = pinStatus;
		break;
	case 2:
		input->Status.pc13 = pinStatus;
		break;
	default:
		// invalid pin
		break;
	}
}

/*
 * Description: Functions as a HAL GPIO callback.
 * Note: no sw debounce incorporated.
 * See YouTube video to learn how to debounce push buttons that use EXTI
 * https://www.youtube.com/watch?v=o0qhmXR5LD0
 */
void GPIO_Callback(uint16_t GPIO_Pin)
{
	if(GPIO_Pin == PA1_Pin)
	{
		GPIO_UpdatePinStatus(&inputs, 0, HAL_GPIO_ReadPin(PA1_GPIO_Port, PA1_Pin));
	}
	else if(GPIO_Pin == PA2_Pin)
	{
		GPIO_UpdatePinStatus(&inputs, 1, HAL_GPIO_ReadPin(PA2_GPIO_Port, PA2_Pin));
	}
	else if(GPIO_Pin == PC13_Pin)
	{
		GPIO_UpdatePinStatus(&inputs, 2, HAL_GPIO_ReadPin(PC13_GPIO_Port, PC13_Pin));
	}
}

/*
 * STM32G071 HAL driver uses Rising and Falling callbacks where other STM32's use 1 callback.
 */
void HAL_GPIO_EXTI_Rising_Callback(uint16_t GPIO_Pin)
{
	GPIO_Callback(GPIO_Pin);
}

void HAL_GPIO_EXTI_Falling_Callback(uint16_t GPIO_Pin)
{
	GPIO_Callback(GPIO_Pin);
}

By using a data structure to represent the look-up table, we can use switch-case to determine what state the input pins are. By checking for current pin state versus the last pin state, you can avoid having case 0 being called again. For case 0, PB12 is low, and PA10 is high. A timer callback is started and after 500ms, it turns Off PA10.

void GPIO_Check(InputStatus_t *input)
{
	if(input->Byte.data[1] != input->Byte.data[0]) // check for change, else do nothing.
	{
		input->Byte.data[1] = input->Byte.data[0]; // copy current state to last state

		switch(input->Byte.data[0]) // index of truth table
		{
		case 0:
			PB12_Off(); // pin is low
			PA10_On(); // pin is high
			TimerCallbackTimerStart(&timerCallback, PA10_Off, 500, TIMER_NO_REPEAT); // start timer to turn off PA10
			break;
		case 1: // all other case, PA12 is On (high state)
		case 2:
		case 3:
		case 4:
		case 5:
		case 6:
		case 7:
		default:
			PB12_On(); // pin is high
			break;
		}
	}
}

And the code for the GPIO outputs

void PA10_On(void)
{
	HAL_GPIO_WritePin(PA10_GPIO_Port, PA10_Pin, GPIO_PIN_SET);
}

void PA10_Off(void)
{
	HAL_GPIO_WritePin(PA10_GPIO_Port, PA10_Pin, GPIO_PIN_RESET);
}

void PB12_On(void)
{
	HAL_GPIO_WritePin(PB12_GPIO_Port, PB12_Pin, GPIO_PIN_SET);
}

void PB12_Off(void)
{
	HAL_GPIO_WritePin(PB12_GPIO_Port, PB12_Pin, GPIO_PIN_RESET);
}

The working code is on Github https://github.com/karlyamashita/Nucleo-G071RB_GPIO_Delay500/wiki