Experimental Physics and
Industrial Control System

Bill Brown <[email protected]> · Fri, 26 Mar 1999 09:51:57 -0800

A while back, Jeff Hill told me:

<<<<<<<<<<
Note that we are attempting to standardize all of our IPAC module 
drivers on Andrew Johnson's drvIpac library. I just finished modifying
his drvIpac.c so that it now supports transparent "intConnect"
functionality in drvIpac so that interrupts work correctly on both
VME and ISA bus systems. It is now the responsibility of the ipac
carrier driver to attach the module driver's ISR to the interrupt
vector.

Peregrine and I have written a carrier driver for the Greensprings
atc40 ISA carrier.
>>>>>>>>>>>>

There is another problem that we might want to talk about; namely that
the PPC boards for compactPCI that we've looked at are big-endian while
the cPCI bus is little-endian.  Somewhere we need to put in some
byte-swapping code.

One problem is that not all reads and writes of the IPacs originate in
same file; there are some reads coming directly out of drvIpac.h.

So - the question I propose is, "Where should the byte-swapping
code go?"

It seems logical (to me) that a good place would be in the carrier
driver, but that is not without it's problems.  I suspect that no
matter where we put it, we'll have some cpu/backplane dependencies
seeping into areas where we don't want it.

I've got a couple of klugey work-arounds for the moment, but a nice
general solution seems appropriate.
-- 

Disclaimer:  Any opinions are my own and have	  | -bill
  nothing to do with the official policy or the   |  [email protected]
  management of L.B.N.L, who probably couldn't    |  Berkeley, CA
  care less about employees who play with trains. |  aka
[email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System