Method SendRequestAndGetCustomReply

src/CAN/CanInterface.cpp:793–891

Send a request to an expansion board and append the response to 'reply'. The response may either be a standard reply or 'replyType'.

// Send a request to an expansion board and append the response to 'reply'. The response may either be a standard reply or 'replyType'.
GCodeResult CanInterface::SendRequestAndGetCustomReply(CanMessageBuffer *buf, CanRequestId rid, const StringRef& reply, uint8_t *extra, CanMessageType replyType, function_ref_noexcept<void(const CanMessageBuffer*) noexcept> callback) noexcept
{
	if (can0dev == nullptr)
	{
		// Transactions sometimes get requested after we have shut down CAN, e.g. when we destroy filament monitors
		CanMessageBuffer::Free(buf);
		return GCodeResult::error;
	}

	const CanAddress dest = buf->id.Dst();
	const CanMessageType msgType = buf->id.MsgType();								// save for possible error message

	{
		// This code isn't re-entrant and it can get called from a task other than Main to shut the system down, so we need to use a mutex
		MutexLocker lock(transactionMutex);

		SendCanMessage(TxBufferIndexRequest, MaxRequestSendWait, buf);
		reprap.GetPlatform().OnProcessingCanMessage();

		const uint32_t whenStartedWaiting = millis();
		uint32_t timeWaiting = 0;
		unsigned int fragmentsReceived = 0;
		for (;;)
		{
			const uint32_t timeout = (timeWaiting < UsualResponseTimeout) ? UsualResponseTimeout - timeWaiting : 1;
			if (!can0dev->ReceiveMessage(RxBufferIndexResponse, timeout, buf))
			{
				break;
			}

			if (reprap.Debug(Module::CAN))
			{
				buf->DebugPrint("Rx1:");
			}

			// The following code allows for the possibility of receiving a StandardReply (e.g. because an error occurred) when we were expecting a different reply.
			// It assumes that any custom reply we may want has the requestId in the same place as a StandardReply.
			const bool matchesRequest = buf->id.Src() == dest
										&& (buf->msg.standardReply.requestId == rid || buf->msg.standardReply.requestId == CanRequestIdAcceptAlways);
			if (matchesRequest && buf->id.MsgType() == CanMessageType::standardReply && buf->msg.standardReply.fragmentNumber == fragmentsReceived)
			{
				if (fragmentsReceived == 0)
				{
					const size_t textLength = buf->msg.standardReply.GetTextLength(buf->dataLength);
					if (textLength != 0)			// avoid concatenating blank lines to existing output
					{
						reply.lcatn(buf->msg.standardReply.text, textLength);
					}
					if (extra != nullptr)
					{
						*extra = buf->msg.standardReply.extra;
					}
					uint32_t waitedFor = millis() - whenStartedWaiting;
					if (waitedFor > longestWaitTime)
					{
						longestWaitTime = waitedFor;
						longestWaitMessageType = (uint16_t)msgType;
					}