Change IPC to exchange data, not pointers.

firmware/common/message_queue.cpp

@@ -26,56 +26,26 @@
 
 using namespace lpc43xx;
 
-bool MessageQueue::push(Message* const message) {
-	/* Returns true if success:
-	 * - Message not in use.
-	 * - FIFO wasn't full.
-	 */
-	if( message->state == Message::State::Free ) {
-		message->state = Message::State::InUse;
-
-		if(	enqueue(message) ) {
-			signal();
-			return true;
-		} else {
-			// Roll back message state.
-			message->state = Message::State::Free;
-		}
+bool MessageQueue::push(const void* const buf, const size_t len) {
+	const auto result = fifo.in_r(buf, len);
+	const bool success = (result == len);
+	if( success ) {
+		signal();
 	}
-
-	return false;
+	return success;
 }
 
-Message* MessageQueue::pop() {
-	/* TODO: Because of architecture characteristics, the two LSBs of the
-	 * message pointer will always be 0. Other (non-pointer) message types
-	 * could be encoded by setting these two bits to non-zero values.
-	 * One of the bits could also be used as an "ack" flag... In fact, a
-	 * pointer message could be turned into an "ack" message, or something
-	 * like that...
-	 * Might be better though to use formal operating structures in the
-	 * message to do synchronization between processors.
-	 */
-	Message* message { nullptr };
-	const auto success = fifo.out(&message, 1);
-	return success ? message : nullptr;
+size_t MessageQueue::pop(void* const buf, const size_t len) {
+	return fifo.out_r(buf, len);
 }
 
 #if defined(LPC43XX_M0)
-bool MessageQueue::enqueue(Message* const message) {
-	return fifo.in(&message, 1);
-}
-
 void MessageQueue::signal() {
 	creg::m0apptxevent::assert();
 }
 #endif
 
 #if defined(LPC43XX_M4)
-bool MessageQueue::enqueue(Message* const message) {
-	return fifo.in(&message, 1);
-}
-
 void MessageQueue::signal() {
 	creg::m4txevent::assert();
 }