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⌂ ∞ ▽ Elite on the BBC Micro and NES

Flight: GalacticHyperdrive

[NES version, Bank 0]

       Name: GalacticHyperdrive                                      [Show more]
       Type: Subroutine
   Category: Flight
    Summary: If we are in space and the countdown has ended, activate the
             galactic hyperdrive

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * TT102 calls GalacticHyperdrive




.GalacticHyperdrive

 LDA QQ12               ; If we are docked (QQ12 = $FF) then jump to dockEd to
 BNE dockEd             ; print an error message and return from the subroutine
                        ; using a tail call (as we can't hyperspace when docked)

 LDA QQ22+1             ; Fetch QQ22+1, which contains the number that's shown
                        ; on-screen during hyperspace countdown

 BEQ Ghy                ; If the countdown is zero, then the galactic hyperdrive
                        ; has been activated, so jump to Ghy to process it

 RTS                    ; Otherwise return from the subroutine