ID:13767 VHDL error at <location>: second actual parameter of function "<name>" must be constant

CAUSE: In a VHDL Design File (.vhd) at the specified location, you specified actual parameters for a function. However, the second parameter you specified is not constant. The second parameter must be constant because you specified FEED_THROUGH for the SYNTHESIS_RETURN attribute in the function's Subprogram Body.

ACTION: Change the second parameter so it is constant.