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).
In vvp, create the .var/str variable for representing strings, and
handle strings in the $display system task.
Add to vvp threads the concept of a stack of strings. This is going to
be how complex objects are to me handled in the future: forth-like
operation stacks. Also add the first two instructions to minimally get
strings to work.
In the parser, handle the variable declaration and make it available
to the ivl_target.h code generator. The vvp code generator can use this
information to generate the code for new vvp support.
This patch makes the code consistently use struct/class in the C++ files,
it removes a couple shadow warnings and where a class pointer is passed to
the C routines, it defines the pointer as a class for C++ and as struct for
C and it removes a namespace std duplication.
The functions (malloc, free, etc.) that used to be provided in
malloc.h are now provided in cstdlib for C++ files and stdlib.h for
C files. Since we require a C99 compliant compiler it makes sense
that malloc.h is no longer needed.
This patch also modifies all the C++ files to use the <c...>
version of the standard C header files (e.g. <cstdlib> vs
<stdlib.h>). Some of the files used the C++ version and others did
not. There are still a few other header changes that could be done,
but this takes care of much of it.
Tran islands must do their calculations using the forced values,
if any. But the output from a port must also be subject to force
filtering. It's a little ugly, but hopefully won't hurt the more
normal case.
During startup it is possible for input port to not yet be
initialized even after some other input ports trigger the
function to be evaluated. Handle this case by substituting
a vector of 'bx for the uninitialized inputs. This will shake
out when the simulation gets going, and only matters for user
defined functions in continuous assignments.
While we're at it, have vec4_unfiltered_value return a reference
to reduce copying of vectors.
For the %mov instruction, implement a vvp_vector4_t::mov method to
manipulate the thread vector directly.
For the %load/v instruction, rework the vec4_value() methods to
avoid creating vvp_vector4_t temporaries, and therefore reduce the
copy overhead.
The first input through a net needs to be propagated, since this
is used as an initialization for the net. This patch also cleans
up wires to not need the width_ member, instead inferring the
width from the saved bit value.
Whether and what to propagate after a release of a part needs to
match the behavior of the full-vector release. Nets need to restore
their driver, and regs need to hold their forced value.
filters need to be able to cope with parts of vectors moving through
the net. It makes the most sense to handle every filter as a part-
selected filter.
When releasing a net, the release needs to propagate the driven
value. When releasing a variable, the driven value must be set
to the previously forced value.
Take wires out of the signals/variables and move them into a filter
instead. This is a big shift, and finally starts us on the path to
divide wires out of signals.
We want the entire force/release subsystem to only reference the
vvp_net_t or vvp_net_fil_t objects in a net. This gives us the
latitude to take wire implementations out of the vvp_net_fun classes.
These methods are type specific, but the code that invokes them
get at them from pointers to filter objects, so it makes sense to
make them abstract methods of the vvp_net_fil_t class.
The vvp_fun_force node converts its input to a call to the
force method of the target node. This eliminates the need for
linking a net to a force input of a signal.
The vvp_net_t port 2 was used to implement force behavior, but that
is no longer how we plan to implement force, so remove it from the
implementation of signal nodes. This currently breaks much of the
force/release functionality, but we'll get it back by other means.
The wire base class cannot carry all the overhead for handling all
the different net types, so split it out into derived classes. This
will also move me closer to splitting wires away from variables.
There is no use implementing the release and deassign methods as
port commands. It's confusing and a waste of vvp_net_t functionality.
It also obscures what needs to be done to more force/release into
the filter object.
This is moving towards moving force/release out of the signal
class. The end-game is to remove all of the wire implementation
out of the functor and into the filter. Variables will remain in
the functor.
Cary R
Larry Doolittle
Christian Taedcke
Stephen Williams
Arun Persaud
Martin Whitaker