How does the blitter decode/encode MFM data?

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#2735

From: Ethan R Dicks
Date: Sun, 14 Jan 1990 21:10

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I have been poring over the RKMs and have not been able to figure this
out... how does the blitter convert bit pairs into bits and bits into
bit pairs for the MFM <-> raw data section of trackdisk.device?

I am looking to adapt this technique for a quick and dirty "zoom" process,
whereby I feed the blitter a byte which gets expanded into 16, 32, 64, or
128 bits for a graphic editor/inspector.  If the MFM code can double/halve
ths input data width, up to four more shifts should be available.

Any pointers? ;-)

-ethan

-- 
Ethan R. Dicks       | ######  This signifies that the poster is a member in
Software Results Corp|   ##    good sitting of Inertia House: Bodies at rest.
940 Freeway Drive N. |   ##
Columbus OH    43229 | ######  "You get it, you're closer."

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Message-ID: <75676@tut.cis.ohio-state.edu>

Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!erd

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!erd
From: erd@tut.cis.ohio-state.edu (Ethan R Dicks)
Newsgroups: comp.sys.amiga.tech
Subject: How does the blitter decode/encode MFM data?
Message-ID: <75676@tut.cis.ohio-state.edu>
Date: 14 Jan 90 21:10:18 GMT
Reply-To: Ethan R Dicks <erd@cis.ohio-state.edu>
Organization: Ohio State University Computer and Information Science
Lines: 19