Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!samsung!usc!apple!agate!ucbvax!POSTGRES.BERKELEY.EDU!dillon
From: dillon@POSTGRES.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga.tech
Subject: DNET 7 bit support
Message-ID: <8911080305.AA03498@postgres.Berkeley.EDU>
Date: 8 Nov 89 03:05:41 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 38


	I'm going away for a week but have almost completed
    modifications to DNet for use over a 7 bit line or with other
    protocols.  This will become the default (with a switch for 8
    bit mode).  That way you guarentee that DNet will run on any
    connection or configuration by default.

	The modifications are as follows:

	SYNC character changed to 0x5B (from 0xFF)

	All packet header and control information redesigned such that
	all bytes fall within the range 0x20-0x7F

	Several new packet types added (invisible to user)

	Currently there is a PCMD_WRITE packet ... a data packet
    containing N bytes of 8 bit data.  I'm adding another packet type
    which will encode binary data into 6 bit bundles (or'd with 0x40
    to make them ascii) for 7 bit mode... resulting in an increase 
    of 25% in the packet size.  DNet will use whichever packet makes
    sense depending on the mode selected and the contents of the 
    packet.

	If anybody wishes to submit a simple block compression
    algorithm that works well with small blocks of data (history 
    storage is alloweds), please email me... I have room for a
    couple new packets and am seriously thinking about adding
    compression to the 8 bit mode.

	The compression would not effect the already slow keyboard
    response as it would be run only on packets larger than, say,
    32 bytes.

	P.S.  THIS MUST BE A FAST COMPRESSION ALGORITHM.  It also
    must use a statically sized history.

				-Matt