Re: A85: SBC HL, DE

To: assembly-85@lists.ticalc.org
Subject: Re: A85: SBC HL, DE
From: Humberto Yeverino <humberto@engr.csufresno.edu>
Date: Tue, 1 Sep 1998 13:02:50 -0700 (PDT)
Delivered-To: assembly-85-outgoing@towerguard.unix.edu.sollentuna.se
In-Reply-To: <c32f22e1.35ec4980@aol.com>
Reply-To: assembly-85@lists.ticalc.org


On Tue, 1 Sep 1998 CashOnly@aol.com wrote:
> > What commands can I use to do this?
> 
> You can use this if you want to find if the outcome is negative...which will
> be the case if de was greater then hl:
> 
>       sbc     hl,de
>     
> 	bit 	7,h  				
> 	jp 		nz,LESSTHENZERO 	; HL<0
if de was greater after sbc hl,de then carry will be set.
so you don't need bit 7,h.
so instead like this:

or a			;he didn't want to subtract carry also
sbc hl,de
jr c,LessThanZero

remember cp is really subtracting and only changing flags.  So when you
subtract you can use the resulting flags to compare.

-Humberto Yeverino Jr.

"I kick ass for the Lord."

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References:

Re: A85: SBC HL, DE

From: CashOnly@aol.com