Guidelines for Mapping Unequal Number of Inputs and Outputs
When mapping unequal numbers of inputs and outputs, use the following guidelines:
Example of More Input Pins than EDIF Input Ports:
If there are more Quartus® Prime input pins than EDIF input ports, map the extra Quartus® Prime input pins to VCC or GND to make them inactive. Be careful to choose appropriate default values.
In this example, the active-low PRN pin of the Quartus® Prime DFF primitive must be driven by VCC to become inactive. The placeholder is the global high or global low signal defined by the EDA tool.
BEGIN FUNCTION dff (CLRN, CLK, D, PRN) RETURNS (Q) FUNCTION "LS174" ("-CL", "CLOCK", "D<0>", "VCC") RETURN ("Q<0>") END
Example of Fewer Input Pins than EDIF Input Ports:
If there are fewer Quartus® Prime input pins than EDIF input ports, insert an extra comma (,) at the end of the Quartus® Prime function input list for each of the EDIF input ports that cannot be mapped to the Quartus® Prime function.
In this example, only the A<0> and B<0> ports of the LS21 function are mapped onto the AND2 primitive. The C<0> and D<0> ports must not be driven by signals within the EDIF Input File (.edf) Definition. A signal that drives an unmapped pin is reported as a node without a destination.
BEGIN FUNCTION and2 (IN1, IN2, , ) RETURNS (OUT) FUNCTION "LS21" ("A<0>", "B<0>", "C<0>", "D<0>") RETURNS (" Y<0>") END
Example of More Output Pins than EDIF Output Ports:
If there are more Quartus® Prime output pins than EDIF output ports, the RETURNS section for the EDIF function must contain an extra comma (,) and double quotation marks (") for each of the unmapped outputs in the Quartus® Prime function.
In this example, the Quartus® Prime software automatically removes the Q1 and Q2 outputs of the custom bill function and all logic within the bill function required to generate these outputs.
BEGIN FUNCTION bill (CLRN, BOG, V, PRTY) RETURNS (Q0, Q1, Q2) FUNCTION "TED" ("-CL", "-BGS", "Z", "-PRTY") RETURNS ("Q0", "", "") END
Example of Fewer Output Pins than EDIF Output Ports:
If there are fewer Quartus® Prime output pins than EDIF output ports, the RETURNS section for the Quartus® Prime function must contain commas for each of the EDIF ports that do not map to a Quartus® Prime function port.
In this example, if the -Q<0> port drives a net (or signal) within the EDIF netlist, the Quartus® Prime software generates the warning Net has no source, because no source pin is driving the signal.
BEGIN FUNCTION dff (CLRN, CLK, D, PRN) RETURNS ( ,Q) FUNCTION "LS74" ("-CL", "CLOCK", "D" <0> , "-PR") RETURNS ("-Q <0> ", "Q <0> ") END