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From: brian@nds.com (Brian Dockter)
Newsgroups: comp.windows.x
Subject: Re: bug in mfb routines??
Message-ID: <1991Jan30.190810.3872@nds.com>
Date: 30 Jan 91 19:08:10 GMT
References: <1991Jan29.200122.20143@cs.columbia.edu>
Reply-To: brian@nds.UUCP (Brian Dockter)
Distribution: usa
Organization: Northwest Digital Systems
Lines: 25

In article <1991Jan29.200122.20143@cs.columbia.edu> shamash@cs.columbia.edu (Ari Shamash) writes:
>I'm having trouble using the mfb routines with a 720x280 bitmap
>display.  There seems to be some kind of step function associated with
>the width.  What seems to be happening is that the routines assume
>that I meant 768x280, so the resulting graphics are skewed to the
>right (as if the horizontal control on the display needs to be
>adjusted).


The first thing that I would check is the actual memory width
of the frame buffer.  This is not always the same as the width
of what is being displayed; if it is wrong, it would produce
results like what are described here.

One limitation which is present on at least some implementations, is
that the real memory width must be a muliple of 32.  The mfb code
accesses memory as an array of 32 bit int's, and keeps track of the
width in multiples of 32 bit int's.

Hope this helps.

-- 
Brian Dockter                    | Northwest Digital Systems
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Internet: brian@nds.com          | FAX: 206-524-0018