gEDA: Icarus FF_LPM and Assertions

[Tom Hawkins <tom-at-NOSPAMconfluent_dot_org>]

I'm almost finished with my Icarus code generator.  Just two more questions:

For synthesizable targets, how can the code generator determine if the 
clock or asynchronous reset for an LPM_FF is sensitive on the positive 
or negative edge?  I tried a negedge FF, expecting to see a NOT gate 
dropped into the final netlist, but no such luck.

Also, are there any assertion capabilities built into Icarus?  I'm not 
sure if there is anything defined in the 2001 spec -- an $assert, maybe? 
  Ideally what I need is an IVL_LPM_ASSERT block that has similar 
semantics as IVL_LPM_FF, except without the output data (q).

In case my posts haven't given it away, I'm working on a formal 
verification plug-in.

-Tom