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Elite on the BBC Micro and NES

Universe: NwS1

[BBC Micro disc version, Docked]

Name: NwS1 [Show more] Type: Subroutine Category: Universe Summary: Flip the sign and double an INWK byte
Context: See this subroutine in context in the source code References: No direct references to this subroutine in this source file

Flip the sign of the INWK byte at offset X, and increment X by 2. This is used by the space station creation routine at NWSPS.
Arguments: X The offset of the INWK byte to be flipped
Returns: X X is incremented by 2
.NwS1 LDA INWK,X \ Load the X-th byte of INWK into A and flip bit 7, EOR #%10000000 \ storing the result back in the X-th byte of INWK STA INWK,X INX \ Add 2 to X INX RTS \ Return from the subroutine