The GetPositionBehind subroutine - Revs on the BBC Micro

       Name: GetPositionBehind                                       [Show more]
       Type: Subroutine
   Category: Drivers
    Summary: Increment X to the next position number (from 0 to 19 and round
             again), which gives the position behind X
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * DrawCars calls GetPositionBehind
             * MoveAndDrawCars calls GetPositionBehind
             * ProcessOvertaking (Part 3 of 3) calls GetPositionBehind
             * SetPlayerPositions calls GetPositionBehind


.GetPositionBehind

 INX                    \ Increment X

 CPX #20                \ If X < 20, jump to getb1 to skip the following
 BCC getb1              \ instruction

 LDX #0                 \ Set X = 0, so repeated calls to this routine will
                        \ increment X up to 19, and then start again at 0

.getb1

 RTS                    \ Return from the subroutine