Subject: Re: 2 Problems
To: None <email@example.com>
From: None <firstname.lastname@example.org>
Date: 11/12/1998 20:59:55
> Charles noted to me a while back that wscons was slow because it only
> processes one character at a time.
I remember a mail from Charles where he blamed slowness to two things:
-one character at a time, as you say
-scrolling by copying
Some profiling showed that the scrolling did indeed use up a significant
fraction of CPU time (not top-ranking, still less than bz^H^Hmemset,
but worth optimizing). Character output was much less.
So I changed the scrolling to use offset registers on VGA.
The reason that the character output is done this way is that
the terminal emulation module interprets the incoming (8-bit)
characters and spits out indices (32-bit) into a potentially larger
character set, keeping state about charset switching control sequences.
It has to touch every incoming character anyway, and even if it did
try to cache a row it would have to transform each character into
the 32-bit font index and put it into a separately allocated array.
I'm not convinced this is worth the effort.
> Any idea if we can fix that problem?
For me, this is not a problem. As long as the vax people don't complain...