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⌂ ∞ ▽ Elite on the 6502

Demo: TAS6

[Elite Demonstration Disc]

       Name: TAS6                                                    [Show more]
       Type: Subroutine
   Category: Demo
    Summary: Negate the vector in XX15 so it points in the opposite direction

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * AttackTarget calls TAS6
             * DOCKIT calls TAS6
             * TACTICS (Part 7 of 7) calls TAS6




 This routine has been copied from the disc version of Elite.



                        \ --- Mod: Code added for Demonstration Disc: --------->

.TAS6

 LDA XX15               \ Reverse the sign of the x-coordinate of the vector in
 EOR #%10000000         \ XX15
 STA XX15

 LDA XX15+1             \ Then reverse the sign of the y-coordinate
 EOR #%10000000
 STA XX15+1

 LDA XX15+2             \ And then the z-coordinate, so now the XX15 vector is
 EOR #%10000000         \ pointing in the opposite direction
 STA XX15+2

 RTS                    \ Return from the subroutine

                        \ --- End of added code ------------------------------->