A89: Re: Assembly-89 Digest V1 #716

To: <assembly-89@lists.ticalc.org>
Subject: A89: Re: Assembly-89 Digest V1 #716
From: "Scott Noveck" <noveck@pluto.njcc.com>
Date: Tue, 13 Apr 1999 22:37:46 -0400
Delivered-To: assembly-89-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-89@lists.ticalc.org
Reply-To: assembly-89@lists.ticalc.org


>Date: Mon, 12 Apr 1999 15:35:05 -0700 (PDT)
>From: Ben Rodgers <bentensai@yahoo.com>
>Subject: A89: get a number
>
>I have a quick question. How would I get a value from
>something like this
>
>map:
>;           |
>;           V
> dc.w 1,2,3,4,5,6,4,2
> dc.w 3,2,4,2,4,1,2,3  <i want that number
> dc.w 2,4,2,4,1,2,3,2       
>
>where I want to get the fourth number in the second
>row.  Thanks.


GetData:
;input: d0 = row (from top, starting at 0)
;       d1 = position from right (starting at 0)
;output: d7 = number
 movem.l d0-d6/a0-a6,-(a7) ;save registers on stack
 lea map(PC),a0            ;a0 = pointer to map
 mulu.w #8,d0              ;replace 8 with # of numbers in row
 add.w d1,d0               ;add offset from left
 lsl.l #1,d0               ;shift d0 1 space right = d0 * 2
                           ;because we're reading words, not bytes
 move.l d0(a0),d7          ;this is allowed, right?
 movem.l (a0)+,d0-d6/a0-a6 ;restore registers
 rts

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