General Description: The CORE Generator COUNTER behavioral model is incorrect when both "Count by Variable" and "Restrict Count = MAX" are selected.
If the COUNT TYPE is set to "Count by Variable" and tied to, say, a value of "2", and the RESTRICT COUNT "Count to Value" is set to "MAX", after reaching the upper limit of the count value, the implemented module goes directly to 0001 (1111+0010) in simulation, whereas the behavioral model cycles back to 0000 first before counting up again to 0010, 0100..., etc.
解决方案
This is a known problem.
As a workaround for bug in the behavioral simulation model, you can perform a post-NGDBUILD functional simulation instead of a behavioral simulation.