DMA and keeping track of reads/writes

I'm using the ni_pcidio driver to collect data with an externally driver
timer and DMA enabled. I'm using current stable releases of both
kcomedilib, comedi and the ni driver.

My question centers around keeping track of how much data is being
DMA'd.  In non-DMA setups, one can use the buf_user_ptr (or another
correct, up-to-date variable....) to track the reading and writing of
data.  I am unsure how to keep track of this with DMA enabled, since
these read/write pointer variables are no longer used. I'd like to know
when new data is arrving and when I can overwrite old data (think
circular buffer with my own rules).

Also, is there an easy way to change the buffer size on the hardware
through kcomedilib?

Regards,
Brent

Received on 2002-08-02Z02:16:33