How to call tightly couple module during C code for NIOS II

Thank you so much gaudetteje! I don't know how to thank you enough.. if only all Altera tutorials were like the way you explained things.

So yes, I've corrected my mistake concerning PIOs and declared internal wires instead, and now I can move two data values into the verilog module and get the output back.. finally!

The next stage for me is to do this calculation on two arrays of values. As you mentioned before, easy way is to have the iteration in NIOS and send the data one at a time. This should not take too long.

But as for using custom instruction or Avalon slave component to take advantage of parallelism, I will certainly come back to you for expert advice :) Any guidance is greatly appreciated.