----- Original Message -----
From: "Russ Nelson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Tuesday, July 11, 2000 9:17 PM
Subject: Re: [Handhelds] Re: Touch Screen Driver Generic Interface for
allLinux SA11x0 platforms.
> Bradley D. LaRonde writes:
> > > It's easier to generate deltas with a timestamp than it is to
generate
> > > constant interval data, if you're given the "wrong" thing.
> >
> > Ugh, I can just see it now, people taking a least-common-demoninator
> > approach because it adapts better to hypothetical delta-spewing
hardware.
>
> How are mice hypothetical?
I know mice are delta beasts. I was talking about touch panels.
> You lose nothing by compressing your data
> stream into "and I saw the same thing for N intervals until I saw
> this". You *do* avoid context switches and kernel/userspace copying,
> which are relatively expensive operations. Remember: every electron
> has to get pushed around by your battery.
I agree with you in principle, but in practice, a touch panel data stream
fluctuates enough so that this simple compression method doesn't buy you
much at all except more electrons running around trying to figure out if
they should (de)compress or not using that lonely extra code we've chucked
into both the kernel and userland side, but practically always getting
disappointed.
And I suppose someone will say "then put some hysteresis and/or noise
filtering in the kernel driver". So now whenever the user holds his pen
perfectly still on the touch panel, all our extra code gets to do it's
dance. :-)
Regards,
Brad
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