STM32 FDCAN: Get all messages from FIFO in RX ISR

src/modm/platform/can/stm32-fdcan/can.cpp.in

@@ -237,25 +237,33 @@ MODM_ISR({{ reg }}_IT0)
 MODM_ISR({{ reg }}_IT1)
 {
 %% if options["buffer.rx"] > 0
+	int_fast16_t msgRetrieveLimit = rxQueue.getMaxSize() - rxQueue.getSize();
+
+	if (msgRetrieveLimit == 0) {
+		modm_assert_continue_ignore(false, "fdcan.rx.buffer",
+			"CAN receive software buffer full, not reading new message(s)!");
+		NVIC_DisableIRQ({{ reg }}_IT1_IRQn);
+		return;
+	}
+
 	RxMessage rxMessage;
 
-	if (rxFifo0HasMessage()) {
+	while (rxFifo0HasMessage() && (msgRetrieveLimit > 0)) {
 		readMsg(rxMessage.message, 0, &rxMessage.filter_id, &rxMessage.timestamp);
-		// acknowledge interrupt flag
-		{{ reg }}->IR = FDCAN_IR_RF0N;
-
-		modm_assert_continue_ignore(rxQueue.push(rxMessage), "fdcan.rx.buffer",
-			"CAN receive software buffer overflowed!", {{ id }});
+		rxQueue.push(rxMessage);
+		msgRetrieveLimit--;
 	}
 
-	if (rxFifo1HasMessage()) {
+	while (rxFifo1HasMessage() && (msgRetrieveLimit > 0)) {
 		readMsg(rxMessage.message, 1, &rxMessage.filter_id, &rxMessage.timestamp);
-		// acknowledge interrupt flag
-		{{ reg }}->IR = FDCAN_IR_RF1N;
-
-		modm_assert_continue_ignore(rxQueue.push(rxMessage), "fdcan.rx.buffer",
-			"CAN receive software buffer overflowed!", {{ id }});
+		rxQueue.push(rxMessage);
+		msgRetrieveLimit--;
 	}
+
+	// Note: When leaving the ISR there still could be more messages available in the FIFO
+	// (if the rxQueue is full). They are still available on the next ISR entrance.
+
+	{{ reg }}->IR = FDCAN_IR_RF0N | FDCAN_IR_RF1N;  // acknowledge interrupt flags
 %% endif
 }
 
@@ -369,6 +377,7 @@ modm::platform::Fdcan{{ id }}::getMessage(can::Message& message, uint8_t *filter
 			(*timestamp) = rxMessage.timestamp;
 		}
 		rxQueue.pop();
+		NVIC_EnableIRQ({{ reg }}_IT1_IRQn);
 		return true;
 	}
 %% else

src/modm/platform/can/stm32-fdcan/can.hpp.in

@@ -14,6 +14,8 @@
 #ifndef MODM_STM32_FDCAN{{ id }}_HPP
 #define MODM_STM32_FDCAN{{ id }}_HPP
 
+#include <optional>
+
 #include <modm/architecture/interface/can.hpp>
 #include <modm/architecture/interface/can_filter.hpp>
 #include <modm/platform/gpio/connector.hpp>