Extra tracks: HookForward

       Name: HookForward                                             [Show more]
       Type: Subroutine
   Category: Extra tracks
    Summary: Move the player forward by an extra segment when edgeSegmentNumber
             is 10
  Deep dive: Secrets of the extra tracks
             Code hooks in the extra tracks
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * ModifyGameCode (Part 3 of 4) calls HookForward


 This routine is called from MovePlayerSegment to move the player forward by an
 extra segment if required.


 Arguments:

   A                    The value of edgeSegmentNumber


.HookForward

 CMP #11                \ If edgeSegmentNumber >= 11, then the player is either
 BCS move1              \ in the same segment, or has moved backwards, so jump
                        \ to move1

                        \ If we get here then edgeSegmentNumber < 11, so
                        \ edgeSegmentNumber must be 10, so we move the player
                        \ forwards by two segments

 JSR MovePlayerForward  \ Move the player forwards by one segment

.move1

 JMP MovePlayerForward  \ Move the player forwards by one segment, returning
                        \ from the subroutine using a tail call