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⌂ ∞ ▽ Elite on the 6502

Dashboard: ABORT2

[Apple II version]

       Name: ABORT2                                                  [Show more]
       Type: Subroutine
   Category: Dashboard
    Summary: Set/unset the lock target for a missile and update the dashboard

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * Main flight loop (Part 11 of 16) calls ABORT2




 Set the lock target for the leftmost missile and update the dashboard.



 Arguments:

   X                    The slot number of the ship to lock our missile onto, or
                        $FF to remove missile lock

   Y                    The new colour of the missile indicator:

                          * #BLACK = black (no missile)

                          * #RED = red (armed and locked)

                          * #WHITE = white (armed)

                          * #GREEN = green (disarmed)



.ABORT2

 STX MSTG               ; Store the target of our missile lock in MSTG

 LDX NOMSL              ; Call MSBAR to update the leftmost indicator in the
 JSR MSBAR              ; dashboard's missile bar, which returns with Y = 0

 STY MSAR               ; Set MSAR = 0 to indicate that the leftmost missile
                        ; is no longer seeking a target lock

 RTS                    ; Return from the subroutine

.msbpars

 EQUB 4, 0, 0, 0, 0     ; These bytes appear to be unused (they are left over
                        ; from the 6502 Second Processor version of Elite)