HSIS: A BDD-Based Environment for Formal Verification

Functional and timing verification are currently the bottlenecks in many design efforts. Simulation and emulation are extensively used for verification. Formal verification is now gaining acceptance in advanced design groups. This has been facilitated by the use of binary decision diagrams (BDDs). This paper describes the essential features of HSIS, a BDD-based environment for formal verification: 1. Open language design, made possible by using a compact and expressive intermediate format known as BLIF-MV. Currently, a synthesis subset of Verilog is supported. 2. Support for both model checking and language containment in a single unified environment, using expressivefairness constraints. 3. Efficient BDD-based algorithms. 4. Debugging environment for both language containment and model checking. 5. Automatic algorithms for the early quantification problem. 6. Support for state minimization using bisimulation and similar techniques. HSIS allows us to experiment with formal verification techniques on a variety of design problems. It also provides an environment for further research in formal verification.