Re: A86: FindPixel

To: <assembly-86@lists.ticalc.org>
Subject: Re: A86: FindPixel
From: "Matt2000" <matt2000@gte.net>
Date: Wed, 6 May 1998 14:24:16 -0400
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


>> It moves the bits 0, 1, 2 and 3 of (hl) to bits 4, 5, 6, and 7 of (hl).
>> It also moves the high bits to where the low one used to be.
>>
>
>Not exactly.  The A register is involved, too.  Here's my cheesy ASCII
>version of the picture in the Z80 databook:


Yeah RLD plays a very major part in Findpixel. If you think it as A(HL) is
acted as one big 16-bit register, then (HL) is shifted left 4-bits (leaving
a 4-bit gap), and the previous value of the low order nibble of A is shifted
into (HL) to fill that low order nibble "gap"

Tutorial #4 on my web page explains Findpixel line by line

-Matt

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