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Message: 4635

Author: jgh@arcade.demon.co.uk

Date: 30/12/2004

Subject: Re: The explanation for a class of Quirky

 

> Message-ID: <cpfvqi+b409@...>

andrewbroad <no_reply@yahoogroups.com> wrote:

> vertical conveyors), I found a simple explanation for the following
> quirky features that only work when going left:
>
> * walking left through walls at head-height;

[snip]

> These features don't work when going right because of the following
> instructions in the right-movement code ONLY which check for a wall-
> block to the right of Willy's head:
>
> 37025: LD A,(32946) ; colour-attribute of wall in current room
> 37028: OR A
> 37029: SBC HL,DE ; HL now points to square to right of Willy's head
> 37031: CP (HL) ; if that square has wall colour-attribute
> 37032: RET Z ; then return without moving Willy to the right

Oo, wonderful. I have added the relevant commentary into the JSW
assembly file at http://www.mdfs.net/Software/JSW

Gimmie a moment to upload it... ;)

--
J.G.Harston - jgh@... - mdfs.net/User/JGH
Badly formed email is deleted unseen as spam

 

 

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