EPICS device support questions

["Gabriel L. Rael" <grael@ztec-inc.com>]

Hello, all.

We are in the process of creating an EPICS interface to our 
oscilloscope.  It is a PCI device with its own kernel driver and user 
space driver with the host processor that will be running our EPICS IOC.

It seems that though EPICS supports a list of communication interfaces 
(GPIB, VME, VXI, serial, etc.), it does not allow for a device to be 
connected above this layer through an ANSI-C API easily.  Though asyn 
device support is a complete solution down to the kernel level, we want 
to be able to leverage our existing drivers.

For packaging up this functionality, we want to create records that map 
directly to our API calls, which are functions with variable arguments, 
some that may be passed by reference for modification.  We have function 
tables containing our calls with variable argument types, but we are not 
seeing a common way to link PVs to function calls with arguments.  In 
the dbd, we are doing something like:  device(ao, INST_IO, devScopeao, 
"scopeAPI").  Can I use the INP and OUT fields arbitrarily, parsing a 
common syntax (i.e. a single string value such as "@function arg1 arg2") 
in the device support layer, to make function wrappers?  Is there a 
general way that we can hook into something that already accomplishes 
this?  Does this break the ability to link PVs properly?  Can I do this 
using the standard record types?  Am I missing something else?

Thanks in advance!

-glr

--
Gabriel L. Rael
Jr. Software Engineer
ZTEC Instruments
http://www.ztecinstruments.com