User guide

2-16
Modeling Your Design
VCS is optimized for simulating sequential devices. Under certain
circumstances VCS infers that an always block is a sequential
device and simulates the always block much faster. This section
describes the coding guidelines you should follow to make VCS infer
an always block as a sequential device.
When writing an always block, if you cannot follow the inferencing
rules for a sequential device there are still things that you should keep
in mind so that VCS simulates the always block faster. This section
also describes the guidelines for coding faster simulating always
blocks that VCS infers to be combinatorial instead of sequential
devices.
Unaccelerated Data Types, Primitives, and Statements
VCS cannot accelerate certain data types and primitives. VCS also
cannot accelerate certain types of statements. This section describes
the data types, primitives, and types of statements that you should
try to avoid.
Avoid Unaccelerated Data Types
VCS cannot accelerate certain data types. The following table lists
these data types:
Data Type Description in IEEE
Std 1364-2001
time and realtime Page 22
real Page 22
named event Page 138
trireg net Page 26
integer array Page 22