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Moving: MVEIT (Part 9 of 9)

[BBC Micro disc version, Flight]

Name: MVEIT (Part 9 of 9) [Show more] Type: Subroutine Category: Moving Summary: Move current ship: Redraw on scanner, if it hasn't been destroyed
Context: See this subroutine in context in the source code Variations: See code variations for this subroutine in the different versions References: No direct references to this subroutine in this source file

This routine has multiple stages. This stage does the following: * If the ship is exploding or being removed, hide it on the scanner * Otherwise redraw the ship on the scanner, now that it's been moved
.MV5 LDA INWK+31 \ Fetch the ship's exploding/killed state from byte #31 AND #%10100000 \ If we are exploding or removing this ship then jump to BNE MVD1 \ MVD1 to remove it from the scanner permanently LDA INWK+31 \ Set bit 4 to keep the ship visible on the scanner ORA #%00010000 STA INWK+31 JMP SCAN \ Display the ship on the scanner, returning from the \ subroutine using a tail call .MVD1 LDA INWK+31 \ Clear bit 4 to hide the ship on the scanner AND #%11101111 STA INWK+31 RTS \ Return from the subroutine