We don't use any of the deprecated functionality, and the added
requirement of Python 3.6+ matches ours.
Having a requirement for pyvcd ~=0.1.4 was actually the cause of
the error I tried to fix in commit 6e1145e2. It had nothing to do
with Jinja2 (though it is definitely still good to have the tighter
requirement on Jinja2); the cause of the error was that pip would
install Jinja2, schedule installing markupsafe, install pyvcd 0.2.0
and then choke on the pyvcd 0.1.4 requirement, which would prevent
it from installing markupsafe &c. Why it does that is beyond me.
I remember thinking that not constraining it properly might bite us
someday, but assumed that Jinja2 will always stay version 2. Now it
looks like Jinja2 3.0.0a1 got released, pip picks it by default, and
it's currently broken (something about markupsafe missing).
Do what needed to be done in the first place.
This commit improves handling of resets in AsyncFIFO in two ways:
* First, resets no longer violate Gray counter CDC invariants.
* Second, write domain reset now empties the entire FIFO.
In some cases, it is necessary to synchronize a reset-like signal but
a new clock domain is not desirable. To address these cases, extract
the implementation of ResetSynchronizer into AsyncFFSynchronizer,
and replace ResetSynchronizer with a thin wrapper around it.
Because write_vcd() is a context manager, this is useful if the VCD
file should be sometimes not written, since it avoids awkward
conditionals with duplicated code. It's not very elegant though.
Fixes#319.
For most toolchains, these are functionally identical, although ports
tend to work a bit better, being the common case. For Vivado, though,
it is necessary to place them on the port because its timing analyzer
considers input buffer delay.
Fixes#301.
Before this commit, there was no way to do so besides creating and
assigning an intermediate signal, which could not be extracted into
a helper function due to Module statefulness.
Fixes#292.
Before this commit, doing something like:
with m.FSM():
with m.State("FOO"):
m.next = "bAR"
with m.State("BAR"):
m.next = "FOO"
would silently create an empty state `bAR` and get stuck in it until
the module is reset. This was done intentionally (in Migen, this code
would in fact miscompile), but in retrospect was clearly a bad idea;
it turns typos into bugs, while in the rare case that branching to
a completely empty state is desired, it is trivial to define one.
Fixes#315.
Before this commit, only signals driven from fragments (in practice,
everything except toplevel inputs) would get written to a VCD file.
Not having toplevel inputs in the dump made debugging ~impossible.
After this commit, all signals the fragment refers to get written to
a VCD file. (More specifically, all signals the compiler assigns
an index to, i.e. signals the generated code reads or writes.)
Fixes#280.
These are not desirable in a HDL, and currently elaborate to broken
RTLIL (after YosysHQ/yosys#1551); prohibit them completely, like
we already do for division and modulo.
Fixes#302.
Since commit 7257c20a, platform code calls create_missing_domains()
before _propagate_domains_up() (as a part of prepare() call). Since
commit a7be3b48, without a platform, create_missing_domains() is
calle after _propagate_domains_up(); because of that, it adds
the missing domain to the fragment. When platform code then calls
prepare() again, this causes an assertion failure.
The true intent behind the platform code being written this way is
that it *overrides* a part of prepare()'s mechanism. Because it was
not changed when prepare() was modified in 7257c20a, the override,
which happened to work by coincidence, stopped working. This is
now fixed by inlining the relevant parts of Fragment.prepare() into
Platform.prepare().
This is not a great solution, but given the amount of breakage this
causes (no platform-using code works), it is acceptable for now.
Fixes#307.
`Module` is an object with a lot of complex and sometimes fragile
behavior that overrides Python attribute accessors and so on.
To prevent user designs from breaking when it is changed, it is not
supposed to be inherited from (unlike in Migen), but rather returned
from the elaborate() method. This commit makes sure it will not be
inherited from by accident (most likely by users familiar with
Migen).
Fixes#286.
A property statement that is created but not added to a module is
virtually always a serious bug, since it can make formal verification
pass when it should not. Therefore, add a warning to it, similar to
UnusedElaboratable.
Doing this to all statements is possible, but many temporary ones are
created internally by nMigen, and the extensive changes required to
remove false positives are likely not worth the true positives.
We can revisit this in the future.
Fixes#303.
