Guidelines for Mapping Unequal Number of Inputs and Outputs
When mapping unequal numbers of inputs and outputs, use the following guidelines:
Use a text editor to modify the appropriate Library Mapping File (.lmf) if a Quartus II function has more or fewer ports than an equivalent third-party function. Include place holders that equate the number of EDIF function ports with the number of Quartus II logic function ports for a particular piece of logic. You can use spaces, closed quotes, or global VCC or GND designations as placeholders.
Note: If an EDIF cell generated from a third-party design tool function contains more inputs than a Quartus II logic function, the Quartus II software ignores the extra ports and issues a warning message. Also a warning message appears if an EDIF cell contains more outputs than the equivalent Quartus II function, and the extra EDIF output signal feeds another function.
If there are more Quartus II input pins than EDIF input ports, map the extra Quartus II 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 II 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
If there are fewer Quartus II input pins than EDIF input ports, insert an extra comma (,) at the end of the Quartus II function input list for each of the EDIF input ports that cannot be mapped to the Quartus II 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). 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
If there are more Quartus II 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 II function.
In this example, the Quartus II 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
If there are fewer Quartus II output pins than EDIF output ports, the RETURNS section for the Quartus II function must contain commas for each of the EDIF ports that do not map to a Quartus II function port.
In this example, if the -Q<0> port drives a net (or signal) within the EDIF netlist, the Quartus II 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
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Example of More Input Pins than EDIF Input Ports:
