* write_path_spice: match side input values to the path arc's transitions
gatePortValues() chose side input values from the first CUDD cube of the
Boolean difference d(f)/d(input), which sensitizes the gate but ignores
the transition directions of the arc the path used:
- For non-unate gates whose Boolean difference is a tautology (xor2,
xnor2) every side variable came back don't-care, and the unknown value
fell through to tie-low in writeSubcktInstVoltSrcs() -- wrong whenever
the path used the when-condition requiring the side high.
- For mux select arcs the cube was an arbitrary data assignment,
unrelated to the output edge the path reported.
Either way the written deck's gate drives the opposite direction from
the reported path: the simulated chain switches with inverted polarity
from that gate onward, edge-qualified arrival measurements fail, and
the deck sums delays from the wrong rise/fall tables.
Constrain the side input condition to the cofactor pair matching this
arc -- f1 & !f0 when the input and driver edges agree (non-inverting),
f0 & !f1 when they differ (inverting) -- threading the gate input
RiseFall from the path stage into gatePortValues(). Also release the
CUDD nodes that were previously leaked (the old code Cudd_Ref'd the
Boolean difference after the generator was freed and never deref'd it).
Fixes#474
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* test: write_path_spice
arc-sense regression for #474, and outlined in #475
---------
Co-authored-by: Brian Degnan <bpdegnan@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Brian Degnan