When nets are assigned directly to a net, we need to create a driver
to carry the strength. Normally, the implied drive of a continuous
assignment is carried by whatever gate the r-value expression ends
with, but with simble net-to-net assignment, there is no net so we
need to install a BUFZ to carry the assignment.
convert the continuous assign elaboration to use elaborate_expr
and synthesize methods instead of the elaborate_net methods of
PExpr. This exposes problems with the synthesize methods, but it
is a better way to do it.
In preparation for using the synthesize method to replace the
elaborate_net method of PExpr, rework the interface to the
synthesize() method. This changes no fnctionality, but does set
up the infrastructure for the next step.
When driving an input port to a module, watch out for the case where
the net is also driven within the instance. If this is the case, take
pains to make sure what goes on in the instance doesn't leak out
through the input port. Add a BUFZ (continuous assignment) to isolate
the context from internal driving.
When generate schems and instance arrays are nested, it takes
multiple iterations of elaborate scope, defparams and evaluate
parameters before everything is worked out. Rework the work item
processing so that the loop elaborates scopes and runs defparams
in phases. The phases are needed so that we can tell when the
remaining defparams are orphaned.
Putting scope elaboration into work queue items allows for handling
more complex processing order. The elaboration_work_list queue drives
the processing of elaborate_scope and parameter evaluation.
This patch adds .cast/int and updates .cast/real to act as a local
(temporary) net and to support either a signed or unsigned input.
The vvp_vector4_t class not can convert an arbitrarily sized double
to a vector value. This removes the restriction of lround().
Also document the new statements.
Generating task/function definitions involves getting the functions
to put themselves into the generate scheme instead of the module,
and getting elaboration to elaborate those definitions in the
generate scheme.
Named begin/end blocks burried within generate schemes need to be
elaborated. Handle this by remembering to elaborate_scope on the
statements within the generate scheme.
In the process, clean up/regularize some of the member names and
methods.
Rather then join islands while branches are initially created, save the
island creating for the end. This way, the process is actually recursive
and greedy, reliably collecting branches into islands without conflict.
Fold the bi-directional part select into the pass switch (tran) support
so that it can be really bi-directional. This involves adding a new
tranvp device that does part select in tran islands, and reworking the
tran island resolution to handle non-identical nodes. This will be needed
for resistive tran devices anyhow.
NetTran devices must be collected into islands because they are all
a bi-directional mass. This is how vvp will process them and the code
generator will need a head start organizing them.
This involves defining the API for switches and cleaning up the
elaborated form to match the defined ivl_target API. Also add t-dll
code to support the ivl_switch_t functions, and add stub code that
checks the results.
The tran devices include tran, rtran, tranif0/1 and rtranif0/1. These
are all elaborated as options on a NetTran device. It is still not
clear the best way to present tran devices via the ivl_target.h API.
The elaborator improperly allowed user function call nodes to take on
the expression width requested of them. The result was that generated
code had junk pad bits in certain cases.
This patch adds code to push the file and line information
for scope objects (modules, functions, tasks, etc.) to the
runtime. For modules, this includes the definition fields.
This patch adds ifnone functionality. It does not produce an
error when both an ifnone and an unconditional simple module
path are given. For this case the ifnone delays are ignored.
Logical and/or take as inputs condition expressions, which are scalar
expressions. Be sure to reduce vectors using proper logic to get the
right condition value.
This patch adds check to determine if an always block has delay
in it or not. If there is no delay a runtime infinite loop will
occur. For the indeterminate case it will print a warning message
if the new -Winfloop flag is given. This flag is not part of the
-Wall check!
This patch uses the true delay expression count not the truncated
one to check that the number of delay expressions is correct.
It also prints the actual number of expressions it found when
printing the error message.
If implicit nets are declared during elaboration, then the success
of binding during elaboration will depend on the order of the code
in the source file.
This patch reworks much of the ternary code to short circuit when
possible and supports real values better. It adds a blend operator
for real values that returns 0.0 when the values differ and the value
when they match. This deviates slightly from the standard which
specifies that the value for reals is always 0.0 when the conditional
is 'bx. There are also a couple bug fixes.
These fixes have not been ported to continuous assignments yet.
Ternary operators used at compile time and in procedural assignments
should be complete (short circuit and support real values).
When a bit port of a module instance is connected to a vector
argument, the MSB module instance should be connected to the MSB
of the vector argument. This matters only in the rare case that
the %m is used. It also makes wave dumps come out right.
Normally processes are found in the lexical scope of a module, but
there are special cases where processes (other then task/function
definitions) are in other lexical scopes. The most likely case is
initilizations that are in the lexical scope where the assigned
variable is declared.
In the process, the behaviors list is kept in the base PScope class
instead of the Module or any other derived lexical scope class.
Move the storage of wires (signals) out of the Module class into
the PScope base class, and instead of putting the PWires all into
the Module object, distribute them into the various lexical scopes
(derived from PScope) so that the wire names do not need to carry
scope information.
This required some rewiring of elaboration of signals, and rewriting
of lexical scope handling.
All the pform objects that represent lexical scope now are derived
from the PScope class, and are kept in a lexical_scope table so that
the scope can be managed.
Generate case is a complex generate scheme where the items are
sub-schemes of the case generate itself. The parser handles them
something like nested generate statements, but storing the case
guards as the test expression. Then the elaborator notes the
case scheme and reaches into the case item schemes inside to make
up tests, select the generate item, and elaborate.
Padding and continuous assignment caused problems if the continuous
assignment includes a delay. The problem is that the padding was
not necessarily included in the delay. Rework the elaboration to
make sure the padding is indeed included in the delay.
Rework the handling of file names to use a perm_string heap to hold
the file names, instead of the custom file name heap in the lexor.
Also rename the get_line to get_fileline to reflect its real duties.
This latter chage touched a lot of files.
This patch causes unnamed generate blocks to be automatically named
using the naming scheme defined in the Verilog-2005 standard. This
is a fix for the problem discussed in pr1821610.
Here are some more array fixes. They are mostly better error messages
instead of just asserting and some code cleanup. The one new thing
that probably should have been a separate submission is that down
indexed part select [base -: width] can now be a lvalue.
@* was only expanding to input nets. nex_input() for blocks was removing
any output net that was also an input. There was also a bug in how output
nets were removed. Only outputs currently defined were removed from the
input list.
always @(*) begin
y = a;
z = y;
end
would report "a" as an input. While
always @(*) begin
z = y;
y = a;
end
would report both "a" and "y" as inputs.
To fix this all nex_inputs now take a flag that when true (the default)
correctly removes any output from the input list. Both the above cases
will now return "a". If the flag is false outputs which are also inputs
will be included in the input list. This is what the @* elaboration code
uses to get the correct sensitivity list.
It is legal in Verilog to bind expressions to ports that do not
match the port width. Icarus Verilog needs to create the necessary
part selects to get the connections right.
Signed-off-by: Stephen Williams <steve@icarus.com>
This patch adds functionality to verify that primitives are given
an appropriate number of ports. For multiple output gates (but,
not, pulldown, pullup) it also reports that Icarus currently does
not support multiple outputs when more than one is given.
This patch adds checks to verify that functions do not invoke
statements that are invalid for them (#, @, wait, enable/call
tasks and non blocking assignment). For reference see section
10.3.4 of 1364-2001.
more general concept of arrays. The NetMemory and NetEMemory
classes are removed from the ivl core program, and the IVL_LPM_RAM
lpm type is removed from the ivl_target API.
Stephen Williams
Larry Doolittle
Cary R
Martin Whitaker
steve