SDF Back Annotate

mydmdm

hi, everyone
i am doing post-layout simulation with a SDF file generated by
PrimeTime command
    "write_sdf"
and i back annotated the sdf file to my design using the system task
$sdf_annotate by:
    $sdf_annotate("sdf_file_name", cell_instance) ;
and i found that ModelSim will not annotate the delay info to my
design, and the warning info is as follow
    Warning: (vsim-SDF-3924) sdf_filename: Out of 11085 SDF
statements, 11085 had null values.
I have not succeeded in shooting this warning information about this
warning in ModelSim's manuals. And the Waveform generated shows that
there is no timing info except the specify in the verilog library.
At last, i found that if i annotate the sdf file by using the ModelSim
command
    vsim -sdfmax
or
    vsim -sdfmin
and ModelSim echoes the info showing that sdf info have been
annotated, and the waveform is ok.
Is anyone can show me something about the $sdf_annotate, esp. about
how ModelSim supporting this task.
And can anyone be kind enough to tell me about what the sdf type (typ,
max, min) mean?
Due to the network problem, i can not view many sites googled, so it
would be appreciated very much that anyone emailing me an emacs
verilog-mode file and other information.
Thanks a lot.
YQ Yang

maplefloat

You can make a small test case and to see if it is SDF format issue.

Normally we dont use primetime's SDF directly for post-simulation. There might need some format alignment.

Shelly_Liu

让我仔细看看