*BSD News Article 8600


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From: veit@du9ds3 (Holger Veit)
Newsgroups: comp.unix.bsd
Subject: Re: [386BSD] Reading joystick port
Date: 7 Dec 92 08:47:46 GMT
Organization: Uni-Duisburg FB9 Datenverarbeitung
Lines: 41
Message-ID: <veit.723718066@du9ds3>
References: <jboyle.723341435@godzilla.cgl.citri.edu.au> <veit.723370235@du9ds3> <1247@galileo.rtn.ca.boeing.com>
Reply-To: veit@du9ds3.fb9dv.uni-duisburg.de
NNTP-Posting-Host: du9ds3.fb9dv.uni-duisburg.de

In <1247@galileo.rtn.ca.boeing.com> dmp3592@galileo.rtn.ca.boeing.com (Dean M. Phillips) writes:

>In article <veit.723370235@du9ds3> veit@du9ds3.fb9dv.uni-duisburg.de writes:
><In <jboyle.723341435@godzilla.cgl.citri.edu.au> jboyle@cgl.citri.edu.au (James Boyle) writes:
><The clean solution is a device driver, say /dev/game. You have to write
><the necessary gameopen, gameclose, gameread, gameprobe, and gameattach 
><routines. See the various lpt drivers for hints (and read some books,
><such as Bach, and Leiffler et al.) to understand the driver interface.
><The problem with the game port is that it has no interrupt, so you need
><some small code which periodically (internal kernel timer routines)
><wakes up the driver to sample the game port (once each some milliseconds).
><
>>Life is not easy.
><
><Holger

>Life is even harder than you think.  A standard IBM game port is
>operated as follows:  An output command triggers a measurement.  To get
>the measurement you have to sit in a tight loop reading the input port
>and count the number of iterations until certain bits change.  This is
>a VERY bad thing in a multitasking environment.

I know that. My reply didn't restrict this. If your sampling is fast enough,
you can use it to calculate the pulse period. I agree polling is bad manner
for a want-to-be UNIX driver.

>IBM: Incompatible Brain-damaged Machinery  ;-)

Unfortunately.

>-- 
>#include <standard_disclaimer.h>
>Dean M. Phillips                                        (206) 393-9333
>Boeing Commercial Airplane Group            dmp3592@galileo.boeing.com

Holger
-- 
|  |   / Dr. Holger Veit         | INTERNET: veit@du9ds3.fb9dv.uni-duisburg.de
|__|  /  University of Duisburg  | "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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