Car geometry: CompareCarSegments

       Name: CompareCarSegments                                      [Show more]
       Type: Subroutine
   Category: Car geometry
    Summary: Calculate the distance between two cars, in terms of segments and
             progress with the current segment
  Deep dive: Placing cars on the track
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * ProcessOvertaking (Part 1 of 3) calls CompareCarSegments


 Extends the distance calculation in CompareSegments by rounding the segment
 numbers used in the calculations, depending on the cars' progress within their
 current segments.


 Arguments:

   X                    The number of driver X

   Y                    The number of driver Y


.CompareCarSegments

 LDA carProgress,Y      \ Set the C flag according to the subtraction:
 SEC                    \
 SBC carProgress,X      \    carProgress for driver ahead
                        \  - carProgress for this driver
                        \
                        \ The progress figures act like a fractional byte
                        \ in the subtraction at the start of the following
                        \ routine, though because only the C flag is kept, they
                        \ only serve to round the result to the nearest integer,
                        \ rather than giving a full 24-bit result

                        \ Fall through into CompareSegments to calculate the
                        \ distance between the two cars, rounding the result
                        \ according to the difference in the cars' progress
                        \ values