Frank,
We do not have much C source code available for either of those chips, but there is some in an Application Note for the 9914 chip. You can view the App Note at:
http://www.ni.com/pdf/instrupd/appnotes/an110.pdf
I would suggest, if possible, that you instead try our TNT4882 chip instead. It is significantly faster than the 9914 or 7210, and we do have source code available for it. Our Driver Developement Kit (DDK) can be modified to work with the TNT4882 chip with minimal trouble. Please e-mail us if you have more questions.
Best regards,
Ryan Tamblin
Applications Engineer
National Instruments