Improve comments

diff --git a/source/libr2c2/trainrouter.cpp b/source/libr2c2/trainrouter.cpp
index fec97823ab73659ed19977a0db228b613fa9c12d..ca3e93d97d6f8b7126c10fa64f3c8aa212b00463 100644 (file)
--- a/source/libr2c2/trainrouter.cpp
+++ b/source/libr2c2/trainrouter.cpp
@@ -91,6 +91,9 @@ void TrainRouter::route_changed()
        bool already_at_end = false;
        if(!routes.empty())
        {
+               /* Find the route that should be used for the next allocated block.  We
+               can't rely on the resync code in block_reserved since we may need to
+               clear the stop marker to continue allocation. */
                TrackIter track = train.get_block_allocator().first().track_iter();
                for(; track; track=track.next())
                {
@@ -106,12 +109,15 @@ void TrainRouter::route_changed()
 
        if(!already_at_end)
        {
+               // We are not at the end of the route now, but might have been before.
                arrival = ON_THE_WAY;
                train.stop_at(0);
                train.refresh_blocks_from(*fncb);
        }
        else if(!arrival)
        {
+               /* If arrival wasn't set before (perhaps because we weren't on a route),
+               set it now. */
                arrival = RESERVED_TO_END;
                train.stop_at(&*fncb.flip());
                train.refresh_blocks_from(*fncb);
@@ -274,13 +280,17 @@ void TrainRouter::block_reserved(Block &block, Train *t)
                if(!t)
                        return;
 
+               // Are we waiting for the other train to pass a sequence point?
                SequencePoint &sp = sequence_points.front();
                if(sp.preceding_train==t && sp.block==&block)
+                       /* The other train's router will advance its sequence on the same
+                       signal and may not have handled it yet. */
                        sequence_check_pending = true;
 
                return;
        }
 
+       // Did we reach our next sequence point?
        if(!sequence_points.empty())
        {
                SequencePoint &sp = sequence_points.front();
@@ -293,7 +303,7 @@ void TrainRouter::block_reserved(Block &block, Train *t)
 
        TrackIter track = train.get_block_allocator().iter_for(block).track_iter();
 
-       // Is the block a turnout?  If so, set it to the proper path.
+       // Is the block a turnout?  If it is, set it to the correct path.
        if(unsigned taddr = block.get_turnout_address())
        {
                int path = (*reserving_route)->get_turnout(taddr);
@@ -301,6 +311,8 @@ void TrainRouter::block_reserved(Block &block, Train *t)
                        track->set_active_path(path);
        }
 
+       /* If the allocator has released blocks from the front, we may need to
+       resync reserving_route. */
        if(reserving_route==routes.end() || !(*reserving_route)->has_track(*track))
        {
                reserving_route = routes.begin();
@@ -315,11 +327,13 @@ void TrainRouter::block_reserved(Block &block, Train *t)
                }
        }
 
-       // Do we need to move to the next route?
+       /* Keep reserving_route pointing to the route containing the block that is
+       expected to be allocated next. */
        for(; track; track=track.next((*reserving_route)->get_path(*track)))
        {
                if(!advance_to_track(reserving_route, *track))
                {
+                       // We've reached the end of the route.  Stop here.
                        arrival = RESERVED_TO_END;
                        train.stop_at(&block);
                        return;
@@ -328,6 +342,7 @@ void TrainRouter::block_reserved(Block &block, Train *t)
                        break;
        }
 
+       // Do we need to wait for another train to pass?
        if(!sequence_points.empty())
        {
                SequencePoint &sp = sequence_points.front();
@@ -342,6 +357,7 @@ void TrainRouter::train_advanced(Block &block)
 
        if(!waypoints.empty())
        {
+               // A waypoint is considered reached when the train has advanced through it.
                const TrackChain &wp = *waypoints.front();
                TrackIter t_iter = b_iter.track_iter();
                if(wp.has_track(*t_iter))
@@ -366,7 +382,7 @@ void TrainRouter::train_rear_advanced(Block &block)
 {
        Track &track = *train.get_block_allocator().iter_for(block).endpoint().track;
 
-       // Have we left some routes completely behind?
+       // Drop any routes that are now completely behind the train.
        for(RouteList::iterator i=routes.begin(); i!=routes.end(); ++i)
                if((*i)->has_track(track))
                {