Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!bruce!monu0.cc.monash.edu.au!monu4!ins760z
From: ins760z@monu4.cc.monash.edu.au (mr  c.r. hames)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Assembly Graphics Help Needed
Message-ID: <1991Jun27.140403.15476@monu0.cc.monash.edu.au>
Date: 27 Jun 91 14:04:03 GMT
References: <91177.015130G60LG@CUNYVM.BITNET>
Sender: news@monu0.cc.monash.edu.au (Usenet system)
Organization: Monash University, Clayton, Vic 3168, Australia
Lines: 32

In article <91177.015130G60LG@CUNYVM.BITNET> G60LG@CUNYVM.BITNET (Anton Mitchell) writes:
>
>     I have tried to get this assembly program to work for the longest.
>Any help would be great. What I dont understand is when assembled and
>executed the bitplanes are not cleared. When allocating the memory I set
>the Clear and Chip flags. But it is not cleared. The only way I have been
>able to clear the bitplanes is by using:
>                                         lea     PlaneAdr,a1
>                                         move.l  PlaneSize*6,d1
>                                 Loop:   move.w  #0,(a1)+
>                                         dbra    d1,Loop

     Besides the faults with your allocate mem putting words into
d0 and d1 instead of longs which has been mentioned and the general
nastiness of wacking in your own copperlist.   REMEMBER that dbra
does one more operation than what the counter started with.  Many
people forget this an overwrite memory not owned by them.

So if you want to clear 100 words.

       move.l   MemPtr,a0
       moveq	#100-1,d1     ; Note The -1
       moveq    #0,d0         ; lets not be too slow hey!
Loop:  move.w   d0,(a0)+
       dbra     d1,Loop


--
Chris Hames         Person to blame for DirWork, VMK, FSDirs, etc
                    And soon for PC-Task?
ins760z@monu4.cc.monash.edu.au  OR  bytey@phoenix.pub.uu.oz.au  OR 3:633/353
I speak for nobody not even myself.....