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From: davidj@brad.inmos.co.uk (David Johnston)
Newsgroups: comp.os.os9
Subject: V_BUSY, who sets it?
Keywords: filemanager V_BUSY
Message-ID: <16115@ganymede.inmos.co.uk>
Date: 17 May 91 23:58:22 GMT
Sender: news@inmos.co.uk
Reply-To: davidj@inmos.UUCP (David Johnston)
Organization: none
Lines: 36


  I have an SCF device driver which serves an IMS B014
VME transputer slave board from a VME based 68k os9
system. This works correctly, with the appropriate
interrupt routines. However due to the single character
nature of SCF drivers, the data transfer rate is a
pitifull 30k/second.
  To get around this I wrote a string based filemanager
, where a buffer pointer and length value are passed
to the device driver. The driver is then able to send
the whole buffer at a speed close to the maximum speed
possible on the B014 (400k/sec).
  Without interrupts, this scheme functions, but when
I introduce code to timeout and wait on an interrupt
the whole this falls over.
  It appears that the V_BUSY location in the static
storage area is set to 0 on entry to the device driver,
and so the IRQ service routine fails to recieve the
process ID of the routine which called F$SLEEP.
  This kind of indicates that the filemanager is
responsible for setting V_BUSY correctly, however none
of my documemtation (Dibble, OS9 manuals & I/O tech ref)
gives information on which routine should do this, or
how.
  Can any OS9 guru's tell me what I am meant to be
doing & whether I've grasped anything approaching the
correct end of the stick?
  Both the driver and the filemanager are written in
68020 machine code.

  Thanks,
        Dave
:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:+-+:
David Johnston, INMOS Ltd,1000 Aztec West, Almondsbury,Bristol, BS12 4SQ, UK.
JANET: davidj@uk.co.inmos     INET: davidj@inmos.com      TEL: +44 454 616616
UUCP: ..{ukc!inmos,uunet!inmos-c}!davidj                  FAX: +44 454 617910