LECSIM: a levelized event-driven compiled logic simulator

LECSIM is an efficient logic simulator which integrates the advantages of event-drive interpretive simulation and levelized compiled simulation. Two techniques contribute to the high efficiency. First, it employs the zero-delay simulation model with levelized event scheduling to eliminate most unnecessary evaluations. Second, it compiles the central event scheduler into simple local scheduling segments which reduces the overhead of event-scheduling. Experimental results show that LECSIM runs about 8-77 times faster than traditional unit-delay event-driven interpretive simulator. LECSIM also provides the option of scheduling with respect to individual gates or to fan-out free blocks. When the circuit is partitioned into fan-out free blocks, the speed increases by a factor of 2-3. With partitioning, the speed of LECSIM is only about 1.5-3.4 times slower than a levelized compiled simulation for the combinational circuits tested