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From: phil@osiris.UUCP (Philip Kos)
Newsgroups: net.arch
Subject: Re: dumber terminal device drivers
Message-ID: <209@osiris.UUCP>
Date: Mon, 1-Apr-85 07:40:07 EST
Article-I.D.: osiris.209
Posted: Mon Apr  1 07:40:07 1985
Date-Received: Fri, 5-Apr-85 11:26:58 EST
References: <327@piggy.UUCP> <2536@nsc.UUCP>
Distribution: net
Organization: Johns Hopkins Hospital
Lines: 46

> . . . . Foo!  When vi is just
> accepting text to be input into a file there doesn't seem to be any
> need for it to wake up every time the user enters a character.  It only
> needs to wake up when something interesting happens - ie. a newline,
> escape or tab - or if text is being inserted into the middle of a line,
> and the text to the right needs to be pushed over.
> 
> What's needed is a general way for vi to tell the terminal handler when
> it needs to be awakened . . . .
> Also, there are a number of characters that must cause it to wake up.


I prefer having input/output character processing in the tty driver.
It keeps me from having to deal with it.  I've actually written a
simple character/line-editing driver, and did not relish the prospect
of building into it all the control offered by the UNIX tty drivers.

Ideally, the processing is there if you need it and skipped if you tell
the driver you don't.  Running in raw mode, there shouldn't be a lot
of overhead.  Of course, "shouldn't" doesn't mean "isn't".  Could some-
body who knows give us the correct story here?  (Notice that we're dis-
cussing some of the same things that caused so much religious flaming
in the RMS "discussion".  Hope this turns out the same - nothing like
a little diatribe to go with my morning coffee. :-)

I don't know about everyone else on the net, but when I'm typing long
lines into a file with vi, I like to have characters echoed *before* I
hit \n.  Also, I think vi would be nicer if it *didn't* insist on rewri-
ting a line every time you insert a character before the end.  This is
not normally a problem, but on slower dialup terminals it sucks.

As for specifying a list of "activation characters", the current "new"
tty driver has three activation characters which apparently signal the
running process (intr, quit, brk) - somebody could try writing a prog-
ram that maps these into \n, ESC, and \t, with the tty driver running
in raw -cbreak mode.  It seems like this would give you what you are
looking for - buffered text input with activation caused by a small set
of control characters.  Of course, you'll be basically ignoring most of
the normal process control signals, but vi does that anyway.

Can this actually be done?  Has anybody out there tried it?  Am I tal-
king through my hat again?  And what about Naomi?


					Phil Kos
					The Johns Hopkins Hospital