[A83] Re: Rotate 16 bits?

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Rotate 16 bits?
From: Max Sikstrom <pengi@molik.org>
Date: Fri, 2 May 2003 02:16:44 +0200
In-Reply-To: <5.1.0.14.0.20030501195801.00ac48b0@mail.comcast.net>
Organization: MoLiK
References: <5.1.0.14.0.20030501195801.00ac48b0@mail.comcast.net>
Reply-To: assembly-83@lists.ticalc.org

On Thu, 01 May 2003 20:00:07 -0400
Gavin Olson <gtolson@comcast.net> wrote:

> Is there an instruction to rotate a sixteen-bit register, or do I have to 
> do something like rotate the low byte and high byte seperately, and then 
> increment the high byte if the low byte produced a carry? (rotating left)
> 
> Along the same lines, is the ADC instruction the same as the x86, where you 
> add if carry, or is it different?
> 
> 
> 

I don't think there is, but you can do this (to shift):

SLA L
RL H

if you want to rotate, you need to set bit 0 to the carry-flag:

SLA L
RL H
JR NC, $+2
SET 0,L

(NOT tested code...)

-- 
Max Sikstrom
pengi@molik.org

MoLiK programming and demo group
http://www.molik.org/

References:

[A83] Rotate 16 bits?

From: Gavin Olson <gtolson@comcast.net>