comunication Nios-Block diagramm

Hello,

i have a Nios system which calculates several values (as long integer)

now i wantto transfer them to a blockdiagramm somehow and multiplie them there or do some other aritmetics with them.

What is the best way to get them from nios to the blockdiagramm?

- over serial uart? how can i multiplie the values then?

- over parallel io? do i have to build a multiplier then out of logic blocks? how do i output the 32bit value in nios then?

or how is this normally done?

thanks in advance..