How to make VHDL code function be called by c code if edit demo web server?

How to make VHDL code function be called by c code if edit demo web server?

if there is a matrix calculation library that would like to be done in VHDL

how this library be called in c code if add this function in demonstration in web server

assume this function is a + b

how to pass parameters a and b from c code to VHDL to calculate and return result to c code

moreover, how faster using this way?