Reply To: Merging coverage databases

[Jim Lewis]

Hi Lyle,

One use model is to write out the coverage database file from separate simulation runs into separate files.  And hence, at the end of test1 we do:

...
UartRx_RxCov.WriteCovDb("Test1_CovDb.txt") ;

Likewise for test2 and so on:

...
UartRx_RxCov.WriteCovDb("Test2_CovDb.txt") ;

Then accumulate the coverage using a separate VHDL program:

UartRx_RxCov.ReadCovDb("Test1_CovDb.txt") ;
for i in 2 to NUM_TESTS_TO_MERGE loop 
  UartRx_RxCov.ReadCovDb("Test" & to_string(i) & "_CovDb.txt", MERGE =>TRUE) ;
end loop ;
... -- do stuff with the merged database

With the current implementation, there is no practical usage of having multiple databases written to the same file.  The append_mode was added to WriteCovDb for symmetry with WriteBin (with very little thought about its application – which is unfortunate and in your case misleading). Your use model of allowing ReadCovDb to merge a set of databases from the same file is interesting – it just was not implemented that way in this version.  I just looked at ReadCovDb, I don’t think it would take too much to modify it to make your use model work. It may be:

    ------------------------------------------------------------
    procedure ReadCovDb (FileName : string; Merge : boolean := FALSE) is
    ------------------------------------------------------------
      file CovDbFile         : text open READ_MODE is FileName ;
    begin
      ReadCovDb(CovDbFile, Merge) ;
      if Merge then
        while not EndFile(CovDbFile) loop
          ReadCovDb(CovDbFile, Merge) ;
        end loop ;
      end if; 
    end procedure ReadCovDb ;

I have not tried this, so there may be subtle issues. Let me know if you try it.

Jim