# Re: developing plustek driver-- questions

Jon Knight (jon@net.lut.ac.uk)
Wed, 22 Jul 1998 12:04:54 +0100 (BST)

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On Tue, 21 Jul 1998, Antal Novak wrote:
> I don't like low-level OS-dependent... I've got FreeBSD and Linux, and I'm
> sure many others use different OSes; it would be too hard to develop
> low-level drivers for every OS. It's much simpler to have to manually
> specify an I/O port (and in the future, it might be auto-detectable)...

But surely the low level driver code has to live in kernel space in order
to make use of interrupts and not busy wait on the port? If the driver
runs in user space, even if it is run as root and niced to a high priority
it isn't going to get the snappy response that a kernel module could get?
Especially seeing as the standard parallel port doesn't come with DMA so
the processor has to be involved in every byte transfered? Whilst
effectively hanging the machine whilst a scan is in progress is OK in the
Windoze world, I don't think it sounds terribly nice for the UNIX
environment. Or is there a cunning way of doing an efficient, platform
independent, user space, low level driver that I've missed?

Tatty bye,

Jim'll

#!/usr/bin/perl -- -Whois++-client-in-6-lines-of-Perl -Beat-that-Z39.50!
use IO::Socket;sub w{$f=shift;$a{$f}=1;($h,$p,$q)=split("/",$f);$s=
IO::Socket::INET->new(PeerAddr=>"$h:$p")||return;print $s "$q\r\n";while(<$s>)
{next if(/^%/);if(/^# SERVER-TO-ASK/){while(<$s>){$x=$1 if/Name: (.*)\r\n$/;$y
=$1 if/Port: (.*)\r\n$/;$f="$x/$y/$q";@j=(@j,$f)if(/^# END/&&!$a{$f})}}else{
print}}close($s)}@j=shift;while(@j){w(pop(@j))}# whois++.pl host/port/query

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