Need help with select() for DIO driver...

Need help with select() for DIO driver...

Post by charles stige » Sun, 08 May 1994 06:48:54

Hello all,

   I am working on a driver for a 144 bit parallel DI/O card.  It needs
to be able to handle reading on interrupts, as well as just reading and
writing.  From reading the KHG it sounds like I need to write a select(),
since I want to be able to put the process to sleep until the interrupt
occurs so the machine can do other things until the read/write is
awakened by the interrupt handling routine.  Unfortunately, the KHG is
also somewhat vague on how everything is done, so could someone out there
answer the following questions for me?

1)  What is select_table *wait?  Does it point to the process to be placed
in the queue?

2)  "Call select_wait() if the device is not ready..." --> How does one
tell if the device is ready?

3)  Does select() call the appropriate read() or write() depending on
sel_type?  Or does the program wishing to read and write call them on a
non-zero return from select() (this seems right to me)?  Also does
sel_type have to be ONLY write, read, or exception?

4)  Does the program reading/writing through the I/O card even call

   Thanks for any help,
                  Chris Stigers

"One seventh of your life will be spent on Mondays - think about it.-
Trent the Uncatchable in "The Long Run" by Daniel Keys Moran


1. device driver for 24/48 DIO, 3xTimer-Card wanted


has someone already written a Linux device driver for a PC card with
24 or 48 digital I/O Channels and three timers on it?
We have the card ME14A from Meilhaus, but I don't know if this
vendor is so well-known. So if you have another driver for a card
with similar behaviour or any other driver for measuring purposes,
it would also a big help for us.

Thanks in advance


Institut fuer Elektrische Maschinen
Technische Universitaet Berlin          Tel. (004930)314-25700

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