A89: Re: address error

To: <assembly-89@lists.ticalc.org>
Subject: A89: Re: address error
From: "Dux Gregis" <assets@eden.rutgers.edu>
Date: Sat, 3 Oct 1998 21:08:49 -0400
Delivered-To: assembly-89-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-89@lists.ticalc.org


Here, I'll give you a little more information so that maybe someone can help
me even if they don't know about the addressing error.  Here is my PutSprite
routine:

PutSprite:
 move.w #30,d2
 move.b #15,d3
 bsr FindPixel
psLoop:
 clr.l d1
 move.w (a1)+,d1
 swap d1
 lsr.l d0,d1
 or.l d1,(a0)
 add.w d2,a0
 dbra.b d3,psLoop
 rts

The FindPixel works; I tested it thoroughly.  FindPixel returns the video
mem address pointer in a0 and the bit offset in d0 from the x and y
coordinates in d0 and d1.  Here is how I called the PutSprite:

 move.l #10,d0
 move.l #20,d1
 move.l sprite(pc),a1
 bsr PutSprite

But it crashes saying address error.  Also does the .l on the lsr
instruction indicate that the register with the number of shifts is a long
or that the operand is a long?

thanks


>
>What causes an "address error"?  These are the two indirect addressing
>instructions I am using: move.w (a1),d1 and or.l d1,(a0), where a0 should
>point to video memory and a1 points to an address within the program.  Or
is
>that error caused by trying to put data to an inaccessable area of memory,
>meaning my pointer is somehow messed up?
>
>thanks
>