How to design a coprocesser?

I am having a problem decoding your question. You can use DSP Builder to realize any specific or generic function that you desire (within reason). IF you design a specific function, then the realized hardware will do exactly what you design it to do.

If you design a general purpose machine, and you integrate intot hat machine the ability to load registers to slect different functions based on what you load into thse registers, you can design a "general purpose execution machine" and realize whatever function you architect it to achieve.

Does this make sense, or should we go around another time.

Advise.