OpenTestability combines metric engines (COP/SCOAP) with reconvergence detection.
Metric engines
| Engine | Outputs | Typical use |
|---|---|---|
| COP | probabilistic controllability and observability | ranking signals for probability-aware test planning |
| SCOAP | CC0, CC1, CO structural testability metrics | fast baseline analysis and traditional DFT scoring |
Core formulas
COP uses probability transfer through gates. Example for two-input AND:
\[P(out=1)=P(a=1)\times P(b=1)\]SCOAP uses integer transfer. Example for two-input AND:
\[CC0(out)=\min(CC0(a),CC0(b))+1\] \[CC1(out)=CC1(a)+CC1(b)+1\]Reconvergence options
| Algorithm | Complexity | Recommended use |
|---|---|---|
basic |
O(n^2) |
quick checks |
simple |
O(n^2 log n) |
default production choice |
advanced |
O(n^3) |
deep debug and difficult circuits |
Selection guideline
- Start with
simplefor almost all production runs. - Use
basicfor speed when rough trend data is enough. - Escalate to
advancedonly for complex fanout interaction analysis.
Parallelization note
Large netlists can automatically benefit from parallel execution in analysis paths. Keep algorithm choice fixed during benchmarking so comparisons remain fair.