Re: A83: Re: Negative or positive?

To: assembly-83@lists.ticalc.org
Subject: Re: A83: Re: Negative or positive?
From: ComAsYuAre@aol.com
Date: Wed, 1 Mar 2000 14:38:57 EST
Reply-To: assembly-83@lists.ticalc.org


In a message dated 3/1/00 12:02:23 PM Eastern Standard Time, 
gte172i@prism.gatech.edu writes:

> When coding assembly, you have to scrap alot of techniques that worked well
>  for Basic, such as adding a positive or negative number to increment a
>  value.
>  
>  just do this...
>  
>   ld a,r                ; or insert your favorite random number routine

Actually to save a byte you could just do
 rra
 jr nc,increaseSpeed

>   and %1                ; 0 or 1
>   jr z,increaseSpeed    ; move right if A=1
>  
>   ld a,(speed)
>   dec a
>   cp 6
>   jr z,skipChangeSpeed  ; dont change speed
>   ld (speed),a
>  
>   jr skipChangeSpeed    ; dont want to increase it either
>  
>  increaseSpeed:
>   ld a,(speed)
>   inc a
>   cp 90
>   jr z,skipChangeSpeed  ; dont change speed
>   ld (speed),a
>  
>  skipChangeSpeed:
>  
>      ; end of routine
>  



----
Jonah Cohen
<ComAsYuAre@aol.com>
http://linux.hypnotic.org/~jonah/ (down)

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