Bit True与Cycle True

Simulations in System Generator are bit-true and cycle-true.

To say a simulation is bit-true
means   that at the boundaries (i.e., interfaces between System Generator blocks and
non-System Generator blocks), a value produced in simulation is bit-for-bit identical to the
corresponding value produced in hardware.

To say a simulation is cycle-true means that at the boundaries, corresponding values are produced at corresponding times. The
boundaries of the design are the points at which System Generator gateway blocks exist.
When a design is translated into hardware, Gateway In (respectively, Gateway Out) blocks
become top-level input (resp., output) ports.