Method SyncWith

src/GCodes/GCodes.cpp:5613–5701

Synchronise motion systems and update user coordinates. Return true if synced, false if we need to wait longer.

// Synchronise motion systems and update user coordinates.
// Return true if synced, false if we need to wait longer.
bool GCodes::SyncWith(GCodeBuffer& thisGb, const GCodeBuffer& otherGb) noexcept
{
	if (thisGb.ExecutingAll())
	{
		return LockAllMovementSystemsAndWaitForStandstill(thisGb);
	}

	if (!LockMovementSystemAndWaitForStandstill(thisGb, thisGb.GetOwnQueueNumber()))
	{
		return false;
	}

	bool synced = false;		// assume failure
	switch (thisGb.syncState)
	{
	case GCodeBuffer::SyncState::running:
		thisGb.syncState = GCodeBuffer::SyncState::syncing;				// tell other input channels that we are waiting for sync
		//debugPrintf("Channel %u changed state to syncing, %u\n", thisGb.GetChannel().ToBaseType(), __LINE__);
		// no break
	case GCodeBuffer::SyncState::syncing:
		if (otherGb.syncState == GCodeBuffer::SyncState::running)
		{
			// The other input channel has either not caught up with us, or it has skipped this sync point, or it is not running
			if (otherGb.IsLaterThan(thisGb))
			{
				// Other input channel has skipped this sync point
				GetMovementState(thisGb).UpdateCoordinatesFromLastKnownEndpoints();
				thisGb.syncState = GCodeBuffer::SyncState::running;
				//debugPrintf("Channel %u changed state to running, %u\n", thisGb.GetChannel().ToBaseType(), __LINE__);
				synced = true;
			}
			// Else other input channel has not caught up with us yet, so wait for it
			break;
		}

		// If we get here then the other input channel is also syncing, so it's safe to use the machine axis coordinates of the axes it owns to update our user coordinates
		GetMovementState(thisGb).UpdateCoordinatesFromLastKnownEndpoints();

		// Now that we no longer need to read axis coordinates from the other motion system, flag that we have finished syncing
		thisGb.syncState = GCodeBuffer::SyncState::synced;
		//debugPrintf("Channel %u changed state to synced, %u\n", thisGb.GetChannel().ToBaseType(), __LINE__);
		// no break
	case GCodeBuffer::SyncState::synced:
		switch (otherGb.syncState)
		{
		case GCodeBuffer::SyncState::running:
			// Other input channel has carried on. If we are the primary, we have finished syncing.
			if (thisGb.LatestMachineState().Executing() || !otherGb.OriginalMachineState().fileState.IsLive() || otherGb.IsLaterThan(thisGb))
			{
				thisGb.syncState = GCodeBuffer::SyncState::running;
				//debugPrintf("Channel %u changed state to running, %u\n", thisGb.GetChannel().ToBaseType(), __LINE__);
				synced = true;
			}
			break;

		case GCodeBuffer::SyncState::syncing:
			// Other input channel hasn't noticed that we are fully synced yet
			break;