This patch implements the $countdrivers system function. It does not
yet support wires connected to islands (and outputs a suitable "sorry"
message when this is detected).
The IEEE standard does not specify the behaviour of a tranif primitive
when its control input is an 'x' or 'z'. vvp currently treats these as
if the tran was turned off, but it would be better to propagate the
uncertainty to the tran bi-directional ports. For compatibility with
other simulators, we adopt the behaviour specified for MOS primitives.
This patch changes all the iterator code to use a prefix ++ instead
of postfix since it is more efficient (no need for a temporary). It
is likely that the compiler could optimize this away, but lets make
it efficient from the start.
This patch adds a few missing initializations to various constructors
in the vvp directory. It also enhances the array alias code to copy
more values from the aliased array.
The tranif input pins are normally nothing special, but sometimes
they are fed back from the switch body. In this case, the control
needs to see the current *output* from the fed back port, in order
to get the results that people expect.
Two bugs:
(1) propagating values through the branch accidentally also
did a part select.
(2) Not all nodes of the branch nexus didn't receive a calculated
values, even though they were all marked as done.
In the process, I cleaned up the code a bit, and documented it for
better understanding.
Tran islands are a kinds of island, so seperate the tran handling
from the core island concept. This will allow for creating new
kinds of islands. (Think analog.)
Cary R
Martin Whitaker
Arun Persaud
Martin Whitaker
Stephen Williams