Experimental Physics and
Industrial Control System

Till Straumann <[email protected]> · Fri, 28 Jan 2011 15:04:10 -0600

A few records that deal with array data use a BPTR
field which holds a pointer to the array.

In some cases it is desirable for device support to
set BPTR rather than using malloced memory that
record support attached there, e.g., because
device support needs special alignment
or wants the record to read from memory-mapped
areas in a device avoiding an extra copy step.
In fact, the aai/aao records *rely* on device support
setting BPTR.

Unfortunately, this is currently broken (I'm looking
at 3.14.8.2) because device support's init_record()
function is only called during pass 1 of record
initialization when links have already been established.
After links are established BPTR must not be changed
because linked records will use a cached pointer.

I see that the problem for aao/aai was fixed in
3.14.12 but it would be nice to be able to set
BPTR for waveforms, too.

-- Till

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System