Re: A86: Please help

To: assembly-86@lists.ticalc.org
Subject: Re: A86: Please help
From: Trent Lillehaugen <tllilleh@polymail.cpunix.calpoly.edu>
Date: Wed, 10 Sep 1997 20:28:45 -0700
References: <3.0.1.32.19970910222954.0080e260@www.thethinker.com> <3328DBEA.3857D48F@wp.cns.net>
Reply-To: assembly-86@lists.ticalc.org

Russ Hanson wrote:

> i am having some trouble. I have a 16x8 map
> Level1:
>   .db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
>   .db 0,1,2,2,0,3,0,1,0,0,0,0,0,0,3,0
>   .db 0,2,0,0,0,3,0,3,0,0,0,1,0,0,2,0
>   .db 0,2,0,0,0,3,0,2,0,0,1,0,2,0,0,0
>   .db 0,0,0,0,0,3,0,0,2,3,2,0,0,0,0,0
>   .db 0,2,0,0,0,3,0,0,0,0,0,0,0,0,2,0
>   .db 0,1,2,2,0,3,0,0,0,0,0,2,0,0,2,0
>   .db 0,0,0,0,0,0,0,0,0,0,0,0,2,0,1,0
> and need to be able to check what is on the map be it 0,1...16.
> depending on x,y coordinates (x is stored into the e register and y
> into
> the d register) i would like the number the x,y coordinates coorispond

   that isn't hard at all.. this should work:you want basically the
y*16+x item in the map right?
so this is basically what we want to do:
hl points to pic
b=0
c = d
c = c*16
c = c+e
hl=hl+bc
right? so in asm this is:

;IN: D = Y coord E = X coord  OUT: A=Value at (e,d)  CHANGED: BC
CoolFunc:
  ld hl,Level1 ;hl points to begining of map
  ld b,0
  ld a,d
  sla a ; a = a * 2
  sla a ; a = a * 4
  sla a ; a = a * 8
  sla a ; a = a *16
  add a,e  ; add your x offset
  ld c,a     ;store that answer into c
  add hl,bc ; add to our  pointer
  ld a,(hl) ; get the value
ret


--
Trent Lillehaugen
Computer Engineering Major
California Polytechnic University, San Luis Obispo
<tllilleh@polymail.calpoly.edu>

Follow-Ups:

Re: A86: Please help

From: Andrew Von Dollen <warn@mail.geocities.com>

References:

Re: A86: my new ti86

From: Joseph Gaffney <gaffney@thethinker.com>

A86: Please help

From: Russ Hanson <russ-h@wp.cns.net>