Path: utzoo!utgpu!water!watmath!clyde!att!ihnp4!cbmvax!carolyn
From: carolyn@cbmvax.UUCP (Carolyn Scheppner CATS)
Newsgroups: comp.sys.amiga.tech
Subject: Re: bitmaps with intuition...
Message-ID: <4105@cbmvax.UUCP>
Date: 25 Jun 88 00:27:08 GMT
References: <4370@gryphon.CTS.COM> <3170@charon.unm.edu> <211@hor-res.UUCP> <18336@cornell.UUCP>
Reply-To: carolyn@cbmvax.UUCP (Carolyn Scheppner CATS)
Organization: Commodore Technology, West Chester, PA
Lines: 25

In article <18336@cornell.UUCP> blandy@marduk (Jim Blandy) writes:
>
>Uh, I may be wrong, but are the bitmaps GUARANTEED to be stored
>one after the other in memory???  If you're lucky in allocation, they
>might be.   The BitMap structure contains an array of pointers to the
>tops of the bitplanes; if b is a BitMap, b.Planes[0] points to the
>first bitplane, b.Planes[1] to the second, etc.  I think you'd be
>better off using that...
>
>Or am I wrong?

You're right.  There is absolutely no guarantee that bitplanes are
right after each other in memory.

You MUST use each plane's bitmap.Planes[] pointer as the base address
of each bitplane.  You can not extrapolate the address of plnae[n]
with a calculation off plane[0].

-- 
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  Carolyn Scheppner -- CATS  Commodore Amiga Technical Support
  PHONE 215-431-9180   UUCP  ...{uunet,allegra,rutgers}!cbmvax!carolyn 

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