Often when IPs are included in a design, the corresponding EDIF representation is encrypted in a .edn file along side the EDIF. This can present a challenge when attempting to place and/or route that design in RapidWright as it doesn't know what is inside the black boxed cells. This allows for a substitute netlist with just the bare bones representation to be supplied externally to enable a place and or route solution to be achieved.

The easiest way to invoke is to call:

EDIFNetlist.setExternalLibrary(EDIFLibrary external);

after a Design (DCP/EDIF) has been loaded. This will automatically populate any black boxes with their corresponding substitute cells from the external library. These cells will return to the black box state when EDIFNetlist.collapseMacroUnisims() is called (a default when writing out a DCP). This is to ensure that when the DCP is written out, that Vivado can fully re-assemble the design from the encrypted and non-encrypted parts. The substitute netlists cannot be part of the output.

Questions to answer:

• The external library will undoubtedly contain references to primitive cell types which are only implicitly provided through setExternalLibrary(). Do we want to change this?
  • Answer: No, keeping the primitive library implicit simplifies things.
• Should we assume the state of the external library is with Unisim macros expanded or collapsed?
  • Answer: Assume the external library is expanded upon call to EDIFNetlist.setExternalLibrary(EDIFLibrary external)