The primitives used have been corrected and changes have been made to the set of signals.
The empirically established need to set the OCEx signal to 1 when using READ_MODE=0 is reflected.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
Now comes *after* example_synth, with references back to it.
Includes some minor adjustment to the `fifo.ys` script to better demonstrate the `select` command.
Still needs an updated section on `show`.
Also includes some other minor updates.
Replace leftover `opt` example source/images with examples specific to the `opt_*` pass.
Currently has images for `opt_expr`, `opt_merge`, `opt_muxtree`, and `opt_share`.
Also includes some other TODO updates.
At the moment the only thing it allows is redirecting `$print` cell
output in a context-dependent manner. In the future, it will allow
customizing handling of `$check` cells (where the default is to abort),
of out-of-range memory accesses, and other runtime conditions with
effects.
This context object also allows a suitably written testbench to add
Verilog-compliant `$time`/`$realtime` handling, albeit it involves
the ceremony of defining a `performer` subclass. Most people will
want something like this to customize `$time`:
int64_t time = 0;
struct : public performer {
int64_t *time_ptr;
int64_t time() const override { return *time_ptr; }
} performer = { &time };
p_top.step(&performer);
This approach to tracking simulation time was a mistake that I did not
catch in review. It has several issues:
1. There is absolutely no requirement to call `step()`, as it is
a convenience function. In particular, `steps` will not be
incremented in submodules if `-noflatten` is used.
2. The semantics of `steps` does not match that of the Verilog `$time`
construct.
3. There is no way to make the semantics of `%t` match that of Verilog.
4. The `module` interface is intentionally very barebones. It is little
more than a container for three method pointers, `reset`, `eval`,
and `commit`. Adding ancillary data to it goes against this.
If similar functionality is introduced again it should probably be
a variable that is global per toplevel design using some object that is
unique for an entire hierarchy of modules, and ideally exposed via
the C API. For now, it is being removed (in this commit) and (in next
commit) the capability is being reintroduced through a context object
that can be specified for `eval()`.
This commit achieves three roughly equally important goals:
1. To bring the rendering code in kernel/fmt.cc and in cxxrtl.h as close
together as possible, with an ideal of only having the bigint library
as the difference between the render functions.
2. To make the treatment of `$time` and `$realtime` in CXXRTL closer to
the Verilog semantics, at least in the formatting code.
3. To change the code generator so that all of the `$print`-to-`string`
conversion code is contained inside of a closure.
There are two reasons to aim for goal (3):
a. Because output redirection through definition of a global ostream
object is neither convenient nor useful for environments where
the output is consumed by other code rather than being printed on
a terminal.
b. Because it may be desirable to, in some cases, ignore the `$print`
cells that are present in the netlist based on a runtime decision.
This is doubly true for an upcoming `$check` cell implementing
assertions, since failing a `$check` would by default cause a crash.
This avoids having to devirtualize them later to get performance back,
and simplifies the code a bit.
The change is prompted by the desire to add a similar observer object
to `eval()`, and a repeated consideration of whether the dispatch on
these should be virtual in first place.
The name `on_commit` was terrible since it would not be called, as one
may conclude from the name, on each `commit()`, but only whenever that
method actually updates a value.
More `literalinclude` and references to source.
Adding `example_show.ys` and `example_lscd.ys`.
Rename `example_00` et al to `example_first` et al.
Also some other minor tidying.
Working on `opt.rst`.
Replace the hardcoded `opt` psuedo code listing with a `literalinclude` from `/cmd/opt.rst`.
Reorder and update `opt_*` list to match current `opt`.
Expand sub-section titles with the function of the pass (keeping the `:cmd:ref:` part at the end to prevent the Esbonio error in vscode when a heading starts with a directive).
Move comments about `clean` and `;;` being aliases into final `opt` subsection.
Also renames `Test suites` -> `Testing Yosys`.
Adds note on `+/`.
Clarifies that we can't entirely skip loading `cells_sim.v`, and then mentions it again later once we need it.
More on final steps (and synthesis outputs).
Catherine
Jannis Harder
Martin Povišer
Miodrag Milanović
YRabbit
github-actions[bot]
N. Engelhardt
Krystine Sherwin
uis
Dag Lem